There are two forms of Vitamin D found in food and supplements: Vitamin D2, which is found in mushrooms, and Vitamin D3, which is found in animal foods. Vitamin D2 is not as bioavailable as D3, which means your body cannot use it as readily; however, it can still raise your vitamin D levels.<a href="#ref-66" id="ref-link-66" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;&lt;a href="https://www.healthline.com/health/vegan-vitamin-d" target="\_blank" rel="noopener noreferrer"&gt;Healthline: The Best Vegan Sources of Vitamin D
&lt;/a&gt;&lt;/p&gt;(Jan 2020)&lt;/div&gt;'>[66]</a> Most D3 supplements are derived from lanolin, a waxy substance secreted by the skin glands of wooly animals. Sheep are sheared, then the lanolin coating is squeezed off the wool. Since the sheep are not killed in the process, this source of D3 will be acceptable to some vegetarians. For vegans, the only acceptable D3 supplements will be the ones explicitly labeled as vegan, which derive their vitamin D3 from lichen extracts.

Is there a difference between Vitamin D2 and Vitamin D3?

Dietary sources of vitamin D include the following foods:<a href="#ref-8" id="ref-link-8" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;&lt;a href="https://ods.od.nih.gov/factsheets/VitaminD-Consumer" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D Fact sheet for consumers. National Institutes of Health (NIH) Office of Dietary Supplements (ODS) updated 2022 Nov 8; cited 2023 May 24
&lt;/a&gt;&lt;/p&gt;&lt;/div&gt;'>[8]</a>
<ul>
<li>fatty fish (such as tuna or salmon) </li>
<li>fish liver oil</li>
<li>beef liver</li>
<li>egg yolks </li>
<li>mushrooms (vitamin D2), especially <a href="https://www.mushrooms.ca/vitamin-d/">mushrooms that have been exposed to UV light</a><a href="#ref-67" id="ref-link-67" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Feldman, et al. &lt;a href=" https://doi.org/10.1016/B978-0-12-809963-6.00060-2" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D in foods: an evolution of knowledge. In: Vitamin D (4th Edition). New York, NY: Elsevier. p. 41-77
&lt;/a&gt;&lt;/p&gt;&lt;/div&gt;'>[67]</a></li>
</ul>
Most foods are not natural sources of vitamin D, but many in the U.S. are fortified with vitamin D. Some common vitamin-D-fortified foods include the following: 
<ul>
<li>milk and other dairy products such as yogurt</li>
<li>soy, almond, and oat milk</li>
<li>orange juice</li>
<li>breakfast cereals</li>
</ul>
Most animal-based foods have some vitamin D in the form of the vitamin D metabolite 25-hydroxyvitamin D (25(OH)D), along with small amounts of vitamin D3. The impact of dietary 25(OH)D on vitamin D status is an ongoing area of research, but it is worth noting that if the 25(OH)D content in foods such as beef, chicken, pork, turkey and eggs were taken into account, the amount of vitamin D present in these foods would be 2-18 times higher than the amount of the parent vitamin alone.<a href="#ref-68" id="ref-link-68" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Taylor CL, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24623845" target="\_blank" rel="noopener noreferrer"&gt;Including food 25-hydroxyvitamin D in intake estimates may reduce the discrepancy between dietary and serum measures of vitamin D status.
&lt;/a&gt;&lt;/p&gt;J Nutr (2014-May)&lt;/div&gt;'>[68]</a>

What are some dietary sources of vitamin D3?

Vitamin D is a fat-soluble nutrient. It is one of the 24 micronutrients critical for human survival. The sun is the major natural source, through eliciting vitamin D production in the skin, but vitamin D is also found naturally in oily fish and eggs and is often added to milk and milk alternatives.

What is vitamin D?

Potentially. Vitamin D status was associated with androgen levels in men in an observational study,<a href="#ref-69" id="ref-link-69" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wehr E, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20050857" target="\_blank" rel="noopener noreferrer"&gt;Association of vitamin D status with serum androgen levels in men
&lt;/a&gt;&lt;/p&gt;Clin Endocrinol (Oxf) (2010 Aug)&lt;/div&gt;'>[69]</a> and a <a href="/glossary/randomized-controlled-trial/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Randomized controlled trial&lt;/h6&gt;&lt;p&gt;Randomized controlled trials (RCTs) are the gold standard for determining whether an intervention actually causes any effects. The use of randomization and control groups helps eliminate the effects of factors other than the treatment being studied.&lt;/p&gt;&lt;/div&gt;">randomized controlled trial</a> found that Vitamin D supplementation (around 3000 IU/day or 75 μg/day) increased testosterone levels in healthy overweight men.<a href="#ref-70" id="ref-link-70" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Pilz S, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21154195" target="\_blank" rel="noopener noreferrer"&gt;Effect of vitamin D supplementation on testosterone levels in men
&lt;/a&gt;&lt;/p&gt;Horm Metab Res (2011 Mar)&lt;/div&gt;'>[70]</a> It is important to note that vitamin D supplementation has not been shown to increase testosterone to supraphysiological levels, nor is there any evidence that supraphysiological vitamin D intake will further enhance testosterone levels beyond moderate-level supplementation. More research is needed to determine the effects of vitamin D supplementation on testosterone levels in different populations.

Can vitamin D status affect testosterone levels?

Low vitamin D levels may be linked to increased all-cause mortality, particularly in older adults. Observational studies have shown a general trend for associations between low vitamin D levels and all-cause mortality in general<a href="#ref-77" id="ref-link-77" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Vieth R, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17344484" target="\_blank" rel="noopener noreferrer"&gt;The urgent need to recommend an intake of vitamin D that is effective.
&lt;/a&gt;&lt;/p&gt;Am J Clin Nutr (2007-Mar)&lt;/div&gt;'>[77]</a> and elderly<a href="#ref-78" id="ref-link-78" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Smit E, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22692022" target="\_blank" rel="noopener noreferrer"&gt;The effect of vitamin D and frailty on mortality among non-institutionalized US older adults.
&lt;/a&gt;&lt;/p&gt;Eur J Clin Nutr (2012-Sep)&lt;/div&gt;'>[78]</a> populations. 
The link between increased all-cause mortality and low vitamin D levels in elderly participants has been confirmed by clinical trials showing decreased mortality with vitamin D3 supplementation.<a href="#ref-79" id="ref-link-79" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Bjelakovic G, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24414552" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D supplementation for prevention of mortality in adults
&lt;/a&gt;&lt;/p&gt;Cochrane Database Syst Rev (2014 Jan 10)&lt;/div&gt;'>[79]</a>
Although associations between low vitamin D levels and increased all-cause mortality in the general population have been reported in observational studies,<a href="#ref-77" id="ref-link-77" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Vieth R, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17344484" target="\_blank" rel="noopener noreferrer"&gt;The urgent need to recommend an intake of vitamin D that is effective.
&lt;/a&gt;&lt;/p&gt;Am J Clin Nutr (2007-Mar)&lt;/div&gt;'>[77]</a> <a href="/glossary/randomized-controlled-trial/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Randomized controlled trial&lt;/h6&gt;&lt;p&gt;Randomized controlled trials (RCTs) are the gold standard for determining whether an intervention actually causes any effects. The use of randomization and control groups helps eliminate the effects of factors other than the treatment being studied.&lt;/p&gt;&lt;/div&gt;">randomized controlled trials</a> with adult participants 18 years or older have failed to confirm this, finding no evidence for an association between vitamin D supplementation and all-cause mortality compared to a placebo.<a href="#ref-80" id="ref-link-80" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zhang Y, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31405892" target="\_blank" rel="noopener noreferrer"&gt;Association between vitamin D supplementation and mortality: systematic review and meta-analysis
&lt;/a&gt;&lt;/p&gt;BMJ (2019 Aug 12)&lt;/div&gt;'>[80]</a>
More research is needed to better understand the influence of vitamin D supplementation on all-cause mortality and longevity in different populations.

Is there a link between vitamin D levels and all-cause mortality?

Multiple sclerosis (MS) is an autoimmune disease that affects the myelin sheath of neurons, which can be thought of as more or less analogous to the insulation on electrical wires. Degradation of the myelin sheath degrades the ability of neurons to propagate signals back and forth between the body and brain, resulting in MS. There are associations between residing in latitudes further away from the equator and increased risk of MS,<a href="#ref-81" id="ref-link-81" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Simpson S, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21478203" target="\_blank" rel="noopener noreferrer"&gt;Latitude is significantly associated with the prevalence of multiple sclerosis: a meta-analysis.
&lt;/a&gt;&lt;/p&gt;J Neurol Neurosurg Psychiatry (2011-Oct)&lt;/div&gt;'>[81]</a> and more sun exposure during childhood is associated with reduced risk of MS during adulthood.<a href="#ref-82" id="ref-link-82" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Islam T, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17646631" target="\_blank" rel="noopener noreferrer"&gt;Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins.
&lt;/a&gt;&lt;/p&gt;Neurology (2007-Jul-24)&lt;/div&gt;'>[82]</a>
Vitamin D has been shown to have a therapeutic effect in mice with experimental autoimmune encephalomyelitis, an animal model for MS. However, human trials to date have not found evidence in support of a role for vitamin D supplementation in the treatment of MS.<a href="#ref-83" id="ref-link-83" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Boltjes R, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34058936" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D supplementation in multiple sclerosis: an expert opinion based on the review of current evidence.
&lt;/a&gt;&lt;/p&gt;Expert Rev Neurother (2021-Jun)&lt;/div&gt;'>[83]</a> More research is needed to better understand whether vitamin D supplementation may benefit any particular populations of people with MS. 
It is also important to note that some of the side effects of toxicity from high-dose vitamin D supplementation, such as fatigue, muscle weakness and urinary dysfunction, mimic the course of MS disease progression,<a href="#ref-84" id="ref-link-84" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Julia Feige, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32188044" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D Supplementation in Multiple Sclerosis: A Critical Analysis of Potentials and Threats
&lt;/a&gt;&lt;/p&gt;Nutrients (2020 Mar 16)&lt;/div&gt;'>[84]</a> underscoring the importance of consulting with a physician before considering aggressive vitamin D supplementation for MS.

Can vitamin D supplementation improve symptoms of multiple sclerosis?

Numerous studies have been published suggesting that vitamin D may help to ameliorate some factors associated with the etiology of <a href="/conditions/alzheimers-disease/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Alzheimer’s Disease&lt;/h6&gt;&lt;p&gt;Alzheimer’s disease is a neurodegenerative disorder that impairs cognitive function, especially memory formation. It is the most common type of dementia.&lt;/p&gt;&lt;/div&gt;">Alzheimer’s disease</a>, prompting some scientists to suggest that it may be helpful for treating or preventing the disease.<a href="#ref-85" id="ref-link-85" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;Lu'o'ng KV, Nguyên LT. &lt;a href=&quot;https://pubmed.ncbi.nlm.nih.gov/22202127&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;The beneficial role of vitamin D in Alzheimer's disease.
&lt;/a&gt;&lt;/p&gt;Am J Alzheimers Dis Other Demen (2011-Nov)&lt;/div&gt;">[85]</a> In support of this idea, Vitamin D treatment has been shown to have neuroprotective effects in in vivo animal studies, and human observational studies have found associations between low vitamin D levels and an increased risk of Alzheimer’s. Additionally, an <a href="/glossary/in-vitro-study/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;In Vitro Study&lt;/h6&gt;&lt;p&gt;&lt;em&gt;In vitro&lt;/em&gt; (Latin for “within the glass”) refers to studies that are performed outside of a living organism. In scientific research, this often involves performing experiments on bacterial, animal, or human cells growing in lab culture dishes.&lt;/p&gt;&lt;/div&gt;">in vitro</a> study of immune cells cultured from the blood of people with Alzheimer’s found that treatment of these cells with vitamin D can increase their breakdown of amyloid-β protein aggregates, which accumulate in the brains of people with Alzheimer’s disease and may be associated with disease pathogenesis.<a href="#ref-86" id="ref-link-86" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;Mizwicki MT, et al. &lt;a href=&quot;https://pubmed.ncbi.nlm.nih.gov/23186989&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;1α,25-dihydroxyvitamin D3 and resolvin D1 retune the balance between amyloid-β phagocytosis and inflammation in Alzheimer's disease patients.
&lt;/a&gt;&lt;/p&gt;J Alzheimers Dis (2013)&lt;/div&gt;">[86]</a> 
However, clinical <a href="/glossary/randomized-controlled-trial/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Randomized controlled trial&lt;/h6&gt;&lt;p&gt;Randomized controlled trials (RCTs) are the gold standard for determining whether an intervention actually causes any effects. The use of randomization and control groups helps eliminate the effects of factors other than the treatment being studied.&lt;/p&gt;&lt;/div&gt;">randomized controlled trials</a> (RCTs) are the only true test of whether or not any given supplement is useful to treat a disease, and the RCTs to date on vitamin D supplementation and Alzheimer’s have reported mixed results. Although one study found that 800 IU (20 μg) of vitamin D taken daily for 12 months significantly improved cognitive function in people with Alzheimer’s disease,<a href="#ref-87" id="ref-link-87" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;Jingya Jia, et al. &lt;a href=&quot;https://pubmed.ncbi.nlm.nih.gov/31296588&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;Effects of vitamin D supplementation on cognitive function and blood Aβ-related biomarkers in older adults with Alzheimer's disease: a randomised, double-blind, placebo-controlled trial
&lt;/a&gt;&lt;/p&gt;J Neurol Neurosurg Psychiatry (2019 Dec)&lt;/div&gt;">[87]</a> many other trials of vitamin D supplementation in people with Alzheimer’s disease have not found significant effects.<a href="#ref-88" id="ref-link-88" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;Chakkera M, et al. &lt;a href=&quot;https://pubmed.ncbi.nlm.nih.gov/36569670&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;The Efficacy of Vitamin D Supplementation in Patients With Alzheimer's Disease in Preventing Cognitive Decline: A Systematic Review.
&lt;/a&gt;&lt;/p&gt;Cureus (2022-Nov)&lt;/div&gt;">[88]</a> Although vitamin D deficiencies may increase Alzheimer’s disease risk, evidence for a therapeut

Can vitamin D supplementation help with treatment or prevention of Alzheimer’s disease?

Preclinical studies on vitamin D have indicated that it may interact with and interfere with various signaling pathways associated with other neurodegenerative diseases, such as Parkinson’s disease, multiple sclerosis, and vascular dementia. Unfortunately, as with Alzheimer’s disease, the results of clinical trials of vitamin D in people with these neurodegenerative diseases have overall been mixed, although some trials have reported positive effects on disease pathology. More large-scale, multicenter clinical trials are needed to better understand when, or if, vitamin D supplementation might be indicated as part of treatment strategies for neurodegenerative disease.<a href="#ref-17" id="ref-link-17" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wang W, Li Y, Meng X. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36820164" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D and neurodegenerative diseases.
&lt;/a&gt;&lt;/p&gt;Heliyon (2023-Jan)&lt;/div&gt;'>[17]</a>

Can vitamin D supplementation help with the treatment or prevention of other neurodegenerative diseases?

Research suggests that there may be a link between low vitamin D levels and the risk of developing <a href="/conditions/erectile-dysfunction/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Erectile Dysfunction&lt;/h6&gt;&lt;p&gt;Erectile dysfunction is a type of male sexual dysfunction characterized by difficulty achieving or maintaining an erection. Erectile dysfunction can be caused by nerve or blood vessel damage, obesity, smoking, or stress.&lt;/p&gt;&lt;/div&gt;">erectile dysfunction</a> (ED), but there is not yet a known dose for treating it. Further research is needed to determine whether supplementation with vitamin D can be beneficial for people suffering from ED.<a href="#ref-91" id="ref-link-91" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Canguven O, Al Malki AH. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32009309" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D and Male Erectile Function: An Updated Review.
&lt;/a&gt;&lt;/p&gt;World J Mens Health (2021-Jan)&lt;/div&gt;'>[91]</a>

Can vitamin D help with erectile dysfunction?

Can vitamin D alleviate depression?

Supplemental vitamin D is associated with a range of benefits, including improved <a href="/conditions/immune-health/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Immune Health&lt;/h6&gt;&lt;p&gt;Immune health refers to the body's ability to resist potentially harmful microorganisms such as viruses and bacteria, and includes both innate and acquired immunity.&lt;/p&gt;&lt;/div&gt;">immune health</a>, <a href="/conditions/bone-health/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Bone Health&lt;/h6&gt;&lt;p&gt;Bone health refers to the strength of bones and the quality of bone structure. Bone health is usually measured as bone mineral density. Bone health is affected by nutrient intake, hormonal regulation, exercise, and age, among other factors.&lt;/p&gt;&lt;/div&gt;">bone health</a>, and well-being. Supplementation may also reduce the risk of <a href="/outcomes/cancer-mortality/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Cancer Mortality&lt;/h6&gt;&lt;p&gt;Cancer mortality refers to a measure of cancer deaths in a particular group of people, often over a period of time. It is commonly expressed as the number of cancer deaths in a group, sample, or population or as the cancer mortality rate per 100,000 people per year.&lt;/p&gt;&lt;/div&gt;">cancer mortality</a>, <a href="/conditions/type-1-diabetes/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Type 1 Diabetes&lt;/h6&gt;&lt;p&gt;Type 1 diabetes is an autoimmune disease in which the pancreas stops producing insulin. It can begin at any age, although most commonly in childhood or adolescence, and requires life-long treatment with insulin.&lt;/p&gt;&lt;/div&gt;">diabetes</a>, and <a href="/conditions/multiple-sclerosis/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Multiple Sclerosis&lt;/h6&gt;&lt;p&gt;Multiple sclerosis is an autoimmune neurological disease characterized by the destruction of the myelin sheaths (nerve insulators) on neurons in the central nervous system. Its symptoms can vary, but eye pain, difficulty balancing, and numbness, tingling, and weakness in limbs are common. Attacks are “multiple” over time and/or location in the nervous system.&lt;/p&gt;&lt;/div&gt;">multiple sclerosis</a>. Vitamin D is often taken for <a href="/conditions/depression/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Depression&lt;/h6&gt;&lt;p&gt;Depression is a chronic state of low mood often associated with hopelessness, apathy, and fatigue. Unlike sadness, depression is a disorder that persists for weeks or months and interferes with daily life.&lt;/p&gt;&lt;/div&gt;">depression</a> and similar mental health issues, but the evidence is mixed as to whether supplementation improves these outcomes.
The effects of vitamin D likely depend on a person’s circulating levels of 25-hydroxyvitamin D (25(OH)D; a form of vitamin D that is measured in blood samples to determine vitamin D status), and many of the benefits of supplementation will only be seen when a deficiency is reversed.

What are vitamin D’s main benefits?

Vitamin D supplements have the potential for interactions with certain medications. Some examples of medications are included below. Since the following is not a comprehensive list, it is important to discuss vitamin D supplementation with your healthcare provider when taking any prescription medications.<a href="#ref-71" id="ref-link-71" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;&lt;a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D Fact sheet for health professionals. MedlinePlus. National Institutes of Health (NIH) Office of Dietary Supplements (ODS). Updated 2022 Aug 12; cited 2023 May 22
&lt;/a&gt;&lt;/p&gt;&lt;/div&gt;'>[71]</a>
Orlistat (also known as Xenical and Alli). These weight loss drugs may reduce vitamin D absorption from the diet and supplements.<a href="#ref-72" id="ref-link-72" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;McDuffie JR, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/12126214" target="\_blank" rel="noopener noreferrer"&gt;Effects of orlistat on fat-soluble vitamins in obese adolescents.
&lt;/a&gt;&lt;/p&gt;Pharmacotherapy (2002-Jul)&lt;/div&gt;'>[72]</a>
Statins. Statin drugs reduce cholesterol synthesis in the body. High levels of vitamin D supplementation can potentially reduce the cholesterol-lowering ability of statin drugs by binding to and competing with a common statin-binding enzyme.<a href="#ref-73" id="ref-link-73" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kim Robien, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/23307906" target="\_blank" rel="noopener noreferrer"&gt;Drug-vitamin D interactions: a systematic review of the literature
&lt;/a&gt;&lt;/p&gt;Nutr Clin Pract (2013 Apr)&lt;/div&gt;'>[73]</a>
Corticosteroid medications, such as prednisone. Corticosteroids reduce vitamin D metabolism, and vitamin D deficiencies were reported to occur with 2x higher frequency in people taking oral corticosteroids compared to non-users.<a href="#ref-74" id="ref-link-74" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Skversky AL, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21956424" target="\_blank" rel="noopener noreferrer"&gt;Association of glucocorticoid use and low 25-hydroxyvitamin D levels: results from the National Health and Nutrition Examination Survey (NHANES): 2001-2006.
&lt;/a&gt;&lt;/p&gt;J Clin Endocrinol Metab (2011-Dec)&lt;/div&gt;'>[74]</a>
Thiazide diuretics. Diuretics are drugs that promote water loss in the body. Because thiazides decrease calcium loss through urine, and vitamin D increases calcium absorption, taking vitamin D supplements alongside thiazides can potentially lead to dangerously high calcium levels (hypercalcemia).<a href="#ref-75" id="ref-link-75" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Crowe M, Wollner L, Griffiths RA. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/6709583" target="\_blank" rel="noopener noreferrer"&gt;Hypercalcaemia following vitamin D and thiazide therapy in the elderly.
&lt;/a&gt;&lt;/p&gt;Practitioner (1984-Mar)&lt;/div&gt;'>[75]</a><a href="#ref-76" id="ref-link-76" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;P J Drinka, W E Nolten. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/6715769" target="\_blank" rel="noopener noreferrer"&gt;Hazards of treating osteoporosis and hypertension concurrently with calcium, vitamin D, and distal diuretics
&lt;/a&gt;&lt;/p&gt;J Am Geriatr Soc (1984 May)&lt;/div&gt;'>[76]</a>

Do vitamin D supplements interact with any medications?

Very high vitamin D levels in the blood exceeding 375 nmol/L or 150 ng/mL are toxic, potentially causing side effects such as loss of appetite, nausea, vomiting, muscle weakness, confusion, dehydration, excessive thirst, and kidney stones.<a href="#ref-7" id="ref-link-7" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Galior K, Grebe S, Singh R. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/30042334" target="\_blank" rel="noopener noreferrer"&gt;Development of Vitamin D Toxicity from Overcorrection of Vitamin D Deficiency: A Review of Case Reports.
&lt;/a&gt;&lt;/p&gt;Nutrients (2018-Jul-24)&lt;/div&gt;'>[7]</a> Extremely high blood levels of vitamin D can even be fatal.<a href="#ref-8" id="ref-link-8" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;&lt;a href="https://ods.od.nih.gov/factsheets/VitaminD-Consumer" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D Fact sheet for consumers. National Institutes of Health (NIH) Office of Dietary Supplements (ODS) updated 2022 Nov 8; cited 2023 May 24
&lt;/a&gt;&lt;/p&gt;&lt;/div&gt;'>[8]</a>
Since vitamin D production in the skin is self-limiting, sun exposure is unlikely to produce vitamin D levels that cause harm (although it may be possible for people with constant, high-level sun exposure, e.g., lifeguards, to synthesize harmfully high levels of Vitamin D).<a href="#ref-9" id="ref-link-9" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Better OS, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/7424691" target="\_blank" rel="noopener noreferrer"&gt;Increased incidence of nephrolithiasis (N) in lifeguards (LG) in Israel.
&lt;/a&gt;&lt;/p&gt;Adv Exp Med Biol (1980)&lt;/div&gt;'>[9]</a> However, vitamin D levels in the blood can readily reach toxic levels with chronic, high-level supplementation.
Although ultra-high-level supplementation is universally considered to be toxic, there’s some debate on what constitutes the upper limit for safe, “moderate-level” supplementation. Taking around 4,000 IU (100 μg) of vitamin D per day for extended periods (≥6 months) seems to increase the risk of hypercalcemia (high blood calcium) and, among older adults, the likelihood of experiencing a fall.<a href="#ref-10" id="ref-link-10" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zittermann A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36853379" target="\_blank" rel="noopener noreferrer"&gt;Long-term supplementation with 3200 to 4000 IU of vitamin D daily and adverse events: a systematic review and meta-analysis of randomized controlled trials.
&lt;/a&gt;&lt;/p&gt;Eur J Nutr (2023-Jun)&lt;/div&gt;'>[10]</a>
A few trials on older adults have found that vitamin D increased the risk of falls,<a href="#ref-11" id="ref-link-11" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Bischoff-Ferrari HA, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26747333" target="\_blank" rel="noopener noreferrer"&gt;Monthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline: A Randomized Clinical Trial
&lt;/a&gt;&lt;/p&gt;JAMA Intern Med (2016 Feb)&lt;/div&gt;'>[11]</a><a href="#ref-12" id="ref-link-12" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Lawrence J Appel, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33284677" target="\_blank" rel="noopener noreferrer"&gt;The Effects of Four Doses of Vitamin D Supplements on Falls in Older Adults : A Response-Adaptive, Randomized Clinical Trial
&lt;/a&gt;&lt;/p&gt;Ann Intern Med (2021 Feb)&lt;/div&gt;'>[12]</a> and one study observed a decrease in <a href="/outcomes/bone-mineral-density/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Bone Mineral Density&lt;/h6&gt;&lt;p&gt;Bone mineral density (BMD) is the density of mineral in bone tissue (more mass in the same area causing an increase in density), and is thought to reflect structural integrity of bones. Improving BMD reduces the risk of osteoporosis and falls in the elderly.&lt;/p&gt;&lt;/div&gt;">bone mineral density</a> among women taking high doses of vitamin D.<a href="#ref-13" id="ref-link-13" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Lauren A Burt, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32777104" target="\_blank" rel="noopener noreferrer"&gt;Adverse Effects of High-Dose Vitamin D Supplementation on Volumetric Bone Density Are Greater in Females than Males
&lt;/a&gt;&lt;/p&gt;J Bone Miner Res (2020 Dec)&lt;/div&gt;'>[13]</a>

What are vitamin D’s main drawbacks?

A moderate amount of fat appears to lead to better vitamin D absorption.
Fat-soluble vitamins 101:
<ul>
<li>There are four fat-soluble vitamins that humans need: vitamins <a href="/supplements/vitamin-a/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vitamin A&lt;/h6&gt;&lt;p&gt;Vitamin A describes a group of metabolites involved in cell and tissue growth, and several bodily functions, including vision, bone metabolism, and immune function. Vitamin A metabolites include &lt;em&gt;preformed vitamin A&lt;/em&gt; — retinols, retinals, retinyl esters, and retinoic acids — and precursors (i.e., &lt;em&gt;provitamin A&lt;/em&gt; molecules) like beta-carotene, which can be converted by the body into the other forms of vitamin A.&lt;/p&gt;&lt;/div&gt;">A</a>, <a href="/supplements/vitamin-d/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vitamin D&lt;/h6&gt;&lt;p&gt;Vitamin D is a fat-soluble vitamin that our skin synthesizes when exposed to the sun. It benefits us in many ways, from bone health to mood.&lt;/p&gt;&lt;/div&gt;">D</a>, <a href="/supplements/vitamin-e/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vitamin E&lt;/h6&gt;&lt;p&gt;Vitamin E is a group of eight different compounds which, collectively, help support antioxidation in the body. Benefits of high doses have uncertain safety, and lower doses seem effective in boosting immunity in the elderly.&lt;/p&gt;&lt;/div&gt;">E</a>, and <a href="/supplements/vitamin-k/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vitamin K&lt;/h6&gt;&lt;p&gt;Vitamin K is an essential vitamin found in plants or produced from intestinal bacteria. It plays an essential role in bone health and regulates blood clotting.&lt;/p&gt;&lt;/div&gt;">K</a>. All the other vitamins are water-soluble.</li>
<li>Fat solubility affects two primary things: how well the vitamin is absorbed with fat-containing meals, and how long it’s stored in your body.</li>
</ul>
Being fat-soluble is a double-edged sword. On the one hand, you can store those vitamins in your body fat and liver, which means you don’t necessarily need daily intake. A sunny vacation can provide you with enough stored vitamin D to last you weeks or even months.<a href="#ref-25" id="ref-link-25" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Mavroeidi A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/23308207" target="\_blank" rel="noopener noreferrer"&gt;Seasonal variation in 25(OH)D at Aberdeen (57°N) and bone health indicators--could holidays in the sun and cod liver oil supplements alleviate deficiency?
&lt;/a&gt;&lt;/p&gt;PLoS One (2013)&lt;/div&gt;'>[25]</a>
On the other hand, you can accidentally overdose on these vitamins more easily. Case studies of vitamin A overdose are actually not that uncommon. Eating the livers of some large fish, seals, or polar bears can easily cause vitamin A poisoning.<a href="#ref-26" id="ref-link-26" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Minuk GY, Kelly JK, Hwang WS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/3356407" target="\_blank" rel="noopener noreferrer"&gt;Vitamin A hepatotoxicity in multiple family members.
&lt;/a&gt;&lt;/p&gt;Hepatology (1988)&lt;/div&gt;'>[26]</a><a href="#ref-27" id="ref-link-27" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chiu YK, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/10584420" target="\_blank" rel="noopener noreferrer"&gt;Acute fish liver intoxication: report of three cases.
&lt;/a&gt;&lt;/p&gt;Changgeng Yi Xue Za Zhi (1999-Sep)&lt;/div&gt;'>[27]</a><a href="#ref-28" id="ref-link-28" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Rodahl K, Moore T. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/16747610" target="\_blank" rel="noopener noreferrer"&gt;The vitamin A content and toxicity of bear and seal liver.
&lt;/a&gt;&lt;/p&gt;Biochem J (1943-Jul)&lt;/div&gt;'>[28]</a>
But most of us don’t eat shark liver or polar bear liver, and vitamin D overdose<a href="#ref-29" id="ref-link-29" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Vieth R. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18290725" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D toxicity, policy, and science
&lt;/a&gt;&lt;/p&gt;J Bone Miner Res (2007 Dec)&lt;/div&gt;'>[29]</a> is less common than vitamin A overdose. In the context of vitamin D intake solely from dietary sources (and not supplements), our problem is less likely to be overdosing on fat-soluble vitamins than it is to be getting enough of them. Let’s take a look at how to get enough vitamin D by taking it with the right amount of fat.
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Vitamin D is one of four fat-soluble vitamins. We don’t need daily intake, since it's stored in body fat, but as many people are low in vitamin D, knowing how much fat you need can be very helpful.
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Some people take a vitamin-D-containing multivitamin in the morning, either with coffee or on an empty stomach. Others take a multivitamin with three eggs and buttered coffee. Whether or not either of these is ideal is an open question. 
It is commonly assumed that vitamin D is better absorbed when taken with a low to moderate amount of fat, as compared to no fat or lots of fat, based on an often-noted study. Specifically, researchers have shown that in people given a single, large dose of vitamin D, taking it with 11 grams of fat leads to higher levels of vitamin D in the bloodstream, compared to taking it with either 35 grams or 0 grams — absorption was 16% higher and 20% higher, respectively.<a href="#ref-3" id="ref-link-3" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Dawson-Hughes B, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/23427007" target="\_blank" rel="noopener noreferrer"&gt;Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation
&lt;/a&gt;&lt;/p&gt;J Bone Miner Res (2013 Aug)&lt;/div&gt;'>[3]</a> An important caveat to this work is that these apparent differences in absorption were only noted by measuring plasma vitamin D levels 12 hours after taking a single large dose of 50,000 IU (1,250 μg). When plasma vitamin D levels were assessed one month and three months after this large dose, the groups didn’t significantly differ in their levels of circulating vitamin D. One alternative interpretation of this work is therefore that vitamin D may be well-absorbed regardless of the amount of fat it is taken with, or on an empty stomach. Changes in plasma vitamin D levels 12 hours postdose with respect to dietary fat content may simply reflect altered rates of absorption into the bloodstream, rather than increased or decreased absolute absorption, as is commonly inferred from the data. Examining plasma vitamin D levels after a single dose at earlier (&lt;12 hours) and later times (&gt;12 hours) might have shed more light on this. Another possibility, given that participants in the above study had the same blood vitamin D levels regardless of whether they took it with some additional fat, is that the limiting factor for achieving long-term steady state vitamin D levels in the blood is more dependent on absorption of vitamin D into the tissues over time, and less on achieving maximal acute vitamin D levels in the blood after a single dose. The ability of fat to acutely enhance blood vitamin D suggests that fat may enhance intestinal absorption. However, it’s not clear that this ultimately matters in terms of achieving stable, steady-state blood vitamin D levels over a longer period of time. In other words, simply taking vitamin D may be more important than what it is taken with. 
The same researchers did a later study that showed 32% higher plasma vitamin D levels when people took a large dose with a meal containing 30 grams of fat, compared to a fat-free meal. But again, they used a single large dose of 50,000 IU of vitamin D.<a href="#ref-30" id="ref-link-30" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Dawson-Hughes B, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/25441954" target="\_blank" rel="noopener noreferrer"&gt;Dietary fat increases vitamin D-3 absorption
&lt;/a&gt;&lt;/p&gt;J Acad Nutr Diet (2015 Feb)&lt;/div&gt;'>[30]</a> Although they tested blood vitamin D levels at additional acute time-points (10, 12, and 14 hours), testing at additional timepoints beyond 14 hours (ideally, 24-48 hours, while the vitamin D meal was still present in the intestines) would have been necessary to see whether or not the plasma levels of the people who ate the fat-free meal ever reached those of those who ate the fatty meal, as one would expect if the effect of a fatty meal is to expedite the intestinal uptake of vitamin D. Unfortunately, the study authors failed to perform any longer-term followup. 
More research is therefore needed to better understand interactions between meal fat content and vitamin D absorption. Taking the evidence all together, it is safe to say that vitamin D is absorbed well enough no matter which type of meal (or no meal) it is taken with. Since vitamin D is stored in body fat, the apparent effects of meal fat content relative to changes in acute absorption may ultimately be less important than regular consumption to support optimal steady-state levels.

How much fat do I need to absorb vitamin D?

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While sunscreens can decrease vitamin D production, they don't appear to do so to a large extent. You need not completely forego sunscreen in order to maintain a healthy vitamin D level. Sun exposure can be bolstered with vitamin D rich foods and supplements to attain sufficient levels.
</div>
Your body can produce <a href="/supplements/vitamin-d/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vitamin D&lt;/h6&gt;&lt;p&gt;Vitamin D is a fat-soluble vitamin that our skin synthesizes when exposed to the sun. It benefits us in many ways, from bone health to mood.&lt;/p&gt;&lt;/div&gt;">vitamin D</a> when the skin is exposed to ultraviolet B (UVB) rays.<a href="#ref-31" id="ref-link-31" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Bikle DD. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21664236" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D metabolism and function in the skin
&lt;/a&gt;&lt;/p&gt;Mol Cell Endocrinol (2011 Dec 5)&lt;/div&gt;'>[31]</a> Yet it is these rays that sunscreens are designed to primarily block.<a href="#ref-32" id="ref-link-32" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Antony R Young, Joël Claveau, Ana Beatris Rossi. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28038885" target="\_blank" rel="noopener noreferrer"&gt;Ultraviolet radiation and the skin: Photobiology and sunscreen photoprotection
&lt;/a&gt;&lt;/p&gt;J Am Acad Dermatol (2017 Mar)&lt;/div&gt;'>[32]</a> So will using sunscreen tank your vitamin D levels?
<h1 class="content-header content-header-h1">Sunscreen and vitamin D production</h1>
Sunscreen can decrease vitamin D production under both controlled laboratory testing and real-world conditions.<a href="#ref-33" id="ref-link-33" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;A Faurschou, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22512875" target="\_blank" rel="noopener noreferrer"&gt;The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial
&lt;/a&gt;&lt;/p&gt;Br J Dermatol (2012 Aug)&lt;/div&gt;'>[33]</a><a href="#ref-34" id="ref-link-34" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Mantas Grigalavicius, Vladimir Iani, Asta Juzeniene. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26977044" target="\_blank" rel="noopener noreferrer"&gt;Layer Thickness of SPF 30 Sunscreen and Formation of Pre-vitamin D
&lt;/a&gt;&lt;/p&gt;Anticancer Res (2016 Mar)&lt;/div&gt;'>[34]</a> This decrease is most notable if sunscreen is used consistently and properly (i.e., when using a broad-spectrum sunscreen, the right sun protection factor (SPF), amount, and reapplication schedule).<a href="#ref-35" id="ref-link-35" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Libon F, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28718005" target="\_blank" rel="noopener noreferrer"&gt;Sunscreens block cutaneous vitamin D production with only a minimal effect on circulating 25-hydroxyvitamin D
&lt;/a&gt;&lt;/p&gt;Arch Osteoporos (2017 Dec)&lt;/div&gt;'>[35]</a><a href="#ref-36" id="ref-link-36" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Bibi Petersen, Hans Christian Wulf. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24313722" target="\_blank" rel="noopener noreferrer"&gt;Application of sunscreen--theory and reality
&lt;/a&gt;&lt;/p&gt;Photodermatol Photoimmunol Photomed (Apr-Jun 2014)&lt;/div&gt;'>[36]</a><a href="#ref-37" id="ref-link-37" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;R E Neale, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/30945275" target="\_blank" rel="noopener noreferrer"&gt;The effect of sunscreen on vitamin D: a review
&lt;/a&gt;&lt;/p&gt;Br J Dermatol (2019 Nov)&lt;/div&gt;'>[37]</a> 
Yet, the amount to which sunscreen decreases vitamin D production appears to be small — a counterintuitive finding.<a href="#ref-38" id="ref-link-38" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;T Passeron, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31069788" target="\_blank" rel="noopener noreferrer"&gt;Sunscreen photoprotection and vitamin D status
&lt;/a&gt;&lt;/p&gt;Br J Dermatol (2019 Nov)&lt;/div&gt;'>[38]</a> How could this be? Two factors have been proposed as possible explanations:<a href="#ref-38" id="ref-link-38" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;T Passeron, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31069788" target="\_blank" rel="noopener noreferrer"&gt;Sunscreen photoprotection and vitamin D status
&lt;/a&gt;&lt;/p&gt;Br J Dermatol (2019 Nov)&lt;/div&gt;'>[38]</a>
<ol>
<li>
People may not be appropriately using sunscreen during periods of sun exposure (i.e., incorrect type, amount, SPF, or application frequency). If not used correctly, UVB rays could easily reach areas of your skin where sunscreen is absent or where coverage is not sufficient enough.
</li>
<li>
While sunscreen does a good job of blocking most UVB rays, it doesn’t entirely block them. A high amount of exposure to UVB rays is not required to kickstart vitamin D production in the skin. So, it’s possible that low amounts of UVB radiation could get past the sunscreen to initiate vitamin D creation.
</li>
</ol>
One important caveat — studies to date have generally been conducted on people with less skin pigmentation (i.e., those with Fitzpatrick skin types 1–3). A different result may be seen in those with Fitzpatrick skin types 4–6.

Does sunscreen decrease vitamin D?

Generally speaking, 5 to 30 minutes of unprotected sun exposure to the hands, face, and arms at least three times a week between 11 a.m. and 3 p.m. is considered enough to keep <a href="https://medlineplus.gov/lab-tests/vitamin-d-test/">blood vitamin D levels</a> out of the deficient range (&lt;30 nmol/L or &lt;12 ng/mL).<a href="#ref-39" id="ref-link-39" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Barbara B Shih, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29730334" target="\_blank" rel="noopener noreferrer"&gt;Fractional Sunburn Threshold UVR Doses Generate Equivalent Vitamin D and DNA Damage in Skin Types I-VI but with Epidermal DNA Damage Gradient Correlated to Skin Darkness
&lt;/a&gt;&lt;/p&gt;J Invest Dermatol (2018 Oct)&lt;/div&gt;'>[39]</a><a href="#ref-40" id="ref-link-40" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Institute of Medicine (US) Committee to Review Dietary Reference Intakes for
Vitamin D and Calcium, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21796828" target="\_blank" rel="noopener noreferrer"&gt;Dietary Reference Intakes for Calcium and Vitamin D
&lt;/a&gt;&lt;/p&gt;&lt;/div&gt;'>[40]</a>
<img src="https://examine.nyc3.digitaloceanspaces.com/files/images/kGyGdccDhd6VBIupGjZ8Wqm5yzlajgD22Wpn2Siw.png" alt="image">
 
When determining how much sunlight you might need, there are two basic factors to consider:
<ul>
<li>The <a href="https://www.epa.gov/sunsafety/uv-index-scale-0">UV index</a> (a measure of UV radiation intensity, from 0 to 11+)</li>
<li>Your Fitzpatrick skin type (a measure of how your skin responds to UV rays, from 1 to 6)</li>
</ul>
When the UV index forecast <a href="https://www.epa.gov/enviro/uv-index-search">in your area</a> is 3 or higher, people with Fitzpatrick skin types 1 or 2 should keep unprotected sun exposure to less than 10 minutes; skin types 3 or 4, less than 15 minutes; and skin types 5 or 6, less than 30 minutes.<a href="#ref-41" id="ref-link-41" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ann R Webb, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29642423" target="\_blank" rel="noopener noreferrer"&gt;Colour Counts: Sunlight and Skin Type as Drivers of Vitamin D Deficiency at UK Latitudes
&lt;/a&gt;&lt;/p&gt;Nutrients (2018 Apr 7)&lt;/div&gt;'>[41]</a><a href="#ref-42" id="ref-link-42" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ann R Webb, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29673142" target="\_blank" rel="noopener noreferrer"&gt;Meeting Vitamin D Requirements in White Caucasians at UK Latitudes: Providing a Choice
&lt;/a&gt;&lt;/p&gt;Nutrients (2018 Apr 17)&lt;/div&gt;'>[42]</a>
<a id="fitzpatrick" class="anchor"></a>
<div class="text-center img-title-wrap">
<div class="img-title mb-1"><h3>Fitzpatrick skin type scale</h3></div>
<img src="https://examine.nyc3.digitaloceanspaces.com/files/images/MAxs4p2VBkxnI55rwPFhovAmFhKs1x7otVfEtckI.png" alt="image" title="Fitzpatrick skin type scale">
</div>
Keep in mind that longer periods of unprotected sun exposure don’t necessarily lead to higher vitamin D production, as the UVB rays will eventually cause the vitamin D in your skin to degrade to an inactive state.<a href="#ref-43" id="ref-link-43" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;A R Webb, B R DeCosta, M F Holick. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/2541158" target="\_blank" rel="noopener noreferrer"&gt;Sunlight regulates the cutaneous production of vitamin D3 by causing its photodegradation
&lt;/a&gt;&lt;/p&gt;J Clin Endocrinol Metab (1989 May)&lt;/div&gt;'>[43]</a> This is a safety mechanism that helps protect your body against <a href="https://examine.com/supplements/vitamin-d/research/#safety-and-toxicity">vitamin D toxicity</a>. 
Don’t stop using sunscreen just to get your vitamin D levels up — a balance can be struck here. In addition to an appropriate dose of sun exposure, you can increase vitamin D <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h3">through diet</a> and <a href="https://examine.com/supplements/vitamin-d/#how-to-take">supplementation</a>. Diet and supplementation strategies will be particularly important for those who live in areas of low sun exposure or at latitudes where the sun’s rays may not be as potent for vitamin D production (greater than 37 degrees north and south of the equator).
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<h1 class="content-header content-header-h1">💡 Tip: Calculate your safe UV exposure for a healthy vitamin D status</h1>
How much UV exposure you need to maximize your body's vitamin D production depends on a number of factors: time of year, location, skin type, weather conditions, and more. Fortunately, the <a href="https://www.nilu.com/">Norwegian Institute for Air Research</a> has developed a calculator, based on peer-reviewed research,<a href="#ref-44" id="ref-link-44" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;Engelsen O, Kylling A. &lt;a href=&quot;https://doi.org/10.1117/1.1885472&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;Fast simulation tool for ultraviolet radiation at the earth's surface
&lt;/a&gt;&lt;/p&gt;Opt Eng (2005 Apr)&lt;/div&gt;">[44]</a><a href="#ref-45" id="ref-link-45" class="ref-link popover" data-tooltip="&lt;div&gt;&lt;p class=&quot;mb-3&quot;&gt;John C Dowdy, Robert M Sayre, Michael F Holick. &lt;a href=&quot;https://pubmed.ncbi.nlm.nih.gov/20398766&quot; target=&quot;\_blank&quot; rel=&quot;noopener noreferrer&quot;&gt;Holick's rule and vitamin D from sunlight
&lt;/a&gt;&lt;/p&gt;J Steroid Biochem Mol Biol (2010 Jul)&lt;/div&gt;">[45]</a><a href="#ref-46" id="ref-link-46" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Vitaly Terushkin, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20363523" target="\_blank" rel="noopener noreferrer"&gt;Estimated equivalency of vitamin D production from natural sun exposure versus oral vitamin D supplementation across seasons at two US latitudes
&lt;/a&gt;&lt;/p&gt;J Am Acad Dermatol (2010 Jun)&lt;/div&gt;'>[46]</a><a href="#ref-47" id="ref-link-47" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ann R Webb, Ola Engelsen. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/16958558" target="\_blank" rel="noopener noreferrer"&gt;Calculated ultraviolet exposure levels for a healthy vitamin D status
&lt;/a&gt;&lt;/p&gt;Photochem Photobiol (Nov-Dec 2006)&lt;/div&gt;'>[47]</a> that takes these factors and more into account. This tool allows you to calculate UV exposure times to obtain optimal vitamin D synthesis without burning your skin.
You can try the easier <a href="https://fastrt.nilu.no/VitD-ez_quartMEDandMED_v2.html">simplified model</a> or the more complex <a href="https://fastrt.nilu.no/VitD_quartMEDandMED_v2.html">full model</a>.
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To summarize: Depending on the UV index and your skin type, 5–30 minutes of unprotected sun exposure to the hands, face, and arms at least three times a week between 11 a.m. and 3 p.m. should be enough to keep your vitamin D levels out of the deficient range. However, for people who live in northerly locations, have darker Fitzpatrick skin types, and/or lack sun exposure, supplementation may be required to maintain adequate vitamin D levels, as dietary sources of vitamin D tend to be inadequate.<a href="#ref-48" id="ref-link-48" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Whiting SJ, Green TJ, Calvo MS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17218094" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D intakes in North America and Asia-Pacific countries are not sufficient to prevent vitamin D insufficiency.
&lt;/a&gt;&lt;/p&gt;J Steroid Biochem Mol Biol (2007-Mar)&lt;/div&gt;'>[48]</a>

How much sun do I need for vitamin D production?

Supplementation is required to prevent a vitamin D deficiency for most people, since dietary sources of vitamin D tend to be inadequate,<a href="#ref-48" id="ref-link-48" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Whiting SJ, Green TJ, Calvo MS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17218094" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D intakes in North America and Asia-Pacific countries are not sufficient to prevent vitamin D insufficiency.
&lt;/a&gt;&lt;/p&gt;J Steroid Biochem Mol Biol (2007-Mar)&lt;/div&gt;'>[48]</a> and the amount of vitamin D produced in the skin through sun exposure can vary with geographical location<a href="#ref-49" id="ref-link-49" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Webb AR, Kline L, Holick MF. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/2839537" target="\_blank" rel="noopener noreferrer"&gt;Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin
&lt;/a&gt;&lt;/p&gt;J Clin Endocrinol Metab (1988 Aug)&lt;/div&gt;'>[49]</a> and individual skin pigmentation.<a href="#ref-50" id="ref-link-50" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Coney P, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22818533" target="\_blank" rel="noopener noreferrer"&gt;Determination of vitamin D in relation to body mass index and race in a defined population of black and white women.
&lt;/a&gt;&lt;/p&gt;Int J Gynaecol Obstet (2012-Oct)&lt;/div&gt;'>[50]</a> 
Vitamin D insufficiency, defined as blood levels less than or equal to 20 ng/mL, may affect as much as 50% of the population worldwide,<a href="#ref-51" id="ref-link-51" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Nair R, Maseeh A. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22629085" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D: The &amp;quot;sunshine&amp;quot; vitamin
&lt;/a&gt;&lt;/p&gt;J Pharmacol Pharmacother (2012 Apr)&lt;/div&gt;'>[51]</a><a href="#ref-52" id="ref-link-52" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Holick MF. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17634462" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D deficiency
&lt;/a&gt;&lt;/p&gt;N Engl J Med (2007 Jul 19)&lt;/div&gt;'>[52]</a> including 41.6% of Americans. Unsurprisingly, low levels are especially common in Americans with darker skin; Vitamin D insufficiency affects 82.1% of the African American/Black population, and 69.2% of the Hispanic population.<a href="#ref-53" id="ref-link-53" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Forrest KY, Stuhldreher WL. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21310306" target="\_blank" rel="noopener noreferrer"&gt;Prevalence and correlates of vitamin D deficiency in US adults
&lt;/a&gt;&lt;/p&gt;Nutr Res (2011 Jan)&lt;/div&gt;'>[53]</a>
<img src="https://examine.nyc3.digitaloceanspaces.com/files/images/ZikaaiJ5dpt2b3xPx2FXoS7ENxpb2ohyu4qPIJ0c.png" alt="image">
More surprisingly, it appears that even people who live in countries with sunlight year round often don’t produce enough vitamin D.<a href="#ref-54" id="ref-link-54" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Haq A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26877203" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D deficiency: A single centre analysis of patients from 136 countries
&lt;/a&gt;&lt;/p&gt;J Steroid Biochem Mol Biol (2016 Nov)&lt;/div&gt;'>[54]</a> This is probably due, at least in part, to most people now working indoors, leaving little skin exposed when venturing outside, and sometimes also using sunscreen.
However, the only way to know for sure if your vitamin D levels are sufficient is to undergo a <a href="https://medlineplus.gov/labtests/vitamindtest.html">25-hydroxyvitamin D blood test</a>. Assessing your vitamin D levels twice in a year — in midsummer and midwinter, when there is the most and least sunlight — is an efficient way of estimating what your levels are around the year.
In Canada and the United States, the Recommended Daily Allowance (RDA) for vitamin D falls between 400 and 800 IU (10–20 μg) (International Units).<a href="#ref-40" id="ref-link-40" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Institute of Medicine (US) Committee to Review Dietary Reference Intakes for
Vitamin D and Calcium, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/21796828" target="\_blank" rel="noopener noreferrer"&gt;Dietary Reference Intakes for Calcium and Vitamin D
&lt;/a&gt;&lt;/p&gt;&lt;/div&gt;'>[40]</a> These amounts, which some researchers criticize as <a href="https://examine.com/nutrition/should-1000-iu-be-the-new-rda-for-vitamin-d/">inadequate</a>,<a href="#ref-55" id="ref-link-55" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Heaney R, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/25763527" target="\_blank" rel="noopener noreferrer"&gt;Letter to Veugelers, P.J. and Ekwaru, J.P., A statistical error in the estimation of the recommended dietary allowance for vitamin D. Nutrients 2014, 6, 4472-4475; doi:10.3390/nu6104472
&lt;/a&gt;&lt;/p&gt;Nutrients (2015 Mar 10)&lt;/div&gt;'>[55]</a><a href="#ref-56" id="ref-link-56" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Veugelers PJ, Ekwaru JP. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/25333201" target="\_blank" rel="noopener noreferrer"&gt;A statistical error in the estimation of the recommended dietary allowance for vitamin D
&lt;/a&gt;&lt;/p&gt;Nutrients (2014 Oct 20)&lt;/div&gt;'>[56]</a> can be obtained naturally from only a few <a href="https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h3">food sources</a>, notably fatty fish (such as salmon, tuna, and sardines). However, in Canada and the United States, milk is often fortified with vitamin D.
<img src="https://examine.nyc3.digitaloceanspaces.com/files/images/1VkYQc0IACKmYDTQvG52eT4nvItEtfJxb7wVh9Hl.png" alt="image">
 
Since few foods are rich in vitamin D, supplementation is a valid option. Should your blood test show that your vitamin D levels are low, start <a href="https://examine.com/nutrition/when-should-i-take-vitamin-d/">supplementing</a> with 2,000 IU (50 μg) a day (a number that, based on the available evidence, should provide the best balance of efficacy and safety), then get tested again after a couple of months.
To summarize: It is estimated that as much as half the world, including more than 40% of Americans, have low levels of vitamin D (≤20 ng/mL). People with darker skin and people who seldom go unprotected under the sun are especially at risk. The only sure way to test for vitamin D deficiency is a 25-hydroxyvitamin D blood test; if levels are low, supplement.

Who needs to supplement vitamin D?

Adequate vitamin D levels are defined as having blood levels of vitamin D (25(OH)D) in the range of 50-125 nmol/L (12-20 ng/mL).<a href="#ref-57" id="ref-link-57" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt; A. Catharine Ross, et al. &lt;a href=" https://nap.nationalacademies.org/read/13050/chapter/1" target="\_blank" rel="noopener noreferrer"&gt;Dietary Reference Intakes for Calcium and Vitamin D (2011). The National Academies Press; Washington, D.C..
&lt;/a&gt;&lt;/p&gt;(2011)&lt;/div&gt;'>[57]</a> The only way to determine vitamin D status is through a blood test. 
Where you live may influence your risk of Vitamin D deficiency. Vitamin D synthesis rates tend to vary with geographical location, which influences the amount of UVB exposure from the sun. People further away from the equator have lower rates of vitamin D synthesis,<a href="#ref-58" id="ref-link-58" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kimlin MG. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18786559" target="\_blank" rel="noopener noreferrer"&gt;Geographic location and vitamin D synthesis.
&lt;/a&gt;&lt;/p&gt;Mol Aspects Med (2008-Dec)&lt;/div&gt;'>[58]</a> and weather patterns associated with more cloud cover and darkness also can also reduce how much vitamin D is made through sun exposure.<a href="#ref-59" id="ref-link-59" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Engelsen O, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/16354110" target="\_blank" rel="noopener noreferrer"&gt;Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness.
&lt;/a&gt;&lt;/p&gt;Photochem Photobiol (2005)&lt;/div&gt;'>[59]</a>
Breastfeeding<a href="#ref-60" id="ref-link-60" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wagner CL, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18977996" target="\_blank" rel="noopener noreferrer"&gt;Prevention of rickets and vitamin D deficiency in infants, children, and adolescents.
&lt;/a&gt;&lt;/p&gt;Pediatrics (2008-Nov)&lt;/div&gt;'>[60]</a> - see “Should vitamin D supplements be given to infants and children?” below. 
Medical conditions that limit the absorption of dietary fats.<a href="#ref-61" id="ref-link-61" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Pappa HM, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18301268" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D status in gastrointestinal and liver disease.
&lt;/a&gt;&lt;/p&gt;Curr Opin Gastroenterol (2008-Mar)&lt;/div&gt;'>[61]</a> As a fat-soluble vitamin, the absorption of vitamin D is dependent on the ability of the gut to absorb fats from the diet.<a href="#ref-62" id="ref-link-62" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Mariana Costa Silva, Tania Weber Furlanetto. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29025082" target="\_blank" rel="noopener noreferrer"&gt;Intestinal absorption of vitamin D: a systematic review
&lt;/a&gt;&lt;/p&gt;Nutr Rev (2018 Jan 1)&lt;/div&gt;'>[62]</a>
Dark skin pigmentation. Darker skin color reduces absorption of UVB, limiting production of vitamin D by the skin during sunlight exposure.<a href="#ref-57" id="ref-link-57" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt; A. Catharine Ross, et al. &lt;a href=" https://nap.nationalacademies.org/read/13050/chapter/1" target="\_blank" rel="noopener noreferrer"&gt;Dietary Reference Intakes for Calcium and Vitamin D (2011). The National Academies Press; Washington, D.C..
&lt;/a&gt;&lt;/p&gt;(2011)&lt;/div&gt;'>[57]</a>
Obesity. People with obesity (defined as a BMI of 30 or more) tend to have lower vitamin D levels compared to people without obesity, which is thought to be caused by an increased sequestration of vitamin D in subcutaneous fat stores.<a href="#ref-57" id="ref-link-57" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt; A. Catharine Ross, et al. &lt;a href=" https://nap.nationalacademies.org/read/13050/chapter/1" target="\_blank" rel="noopener noreferrer"&gt;Dietary Reference Intakes for Calcium and Vitamin D (2011). The National Academies Press; Washington, D.C..
&lt;/a&gt;&lt;/p&gt;(2011)&lt;/div&gt;'>[57]</a> 
Gastric bypass surgery. During gastric bypass surgery, parts of the gastrointestinal tract that absorb vitamin D are bypassed, limiting absorption and potentially causing a deficiency.<a href="#ref-63" id="ref-link-63" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chakhtoura M, Rahme M, El-Hajj Fuleihan G. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29080645" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D Metabolism in Bariatric Surgery.
&lt;/a&gt;&lt;/p&gt;Endocrinol Metab Clin North Am (2017-Dec)&lt;/div&gt;'>[63]</a><a href="#ref-64" id="ref-link-64" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Peterson LA, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/27036669" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D status and supplementation before and after bariatric surgery: a comprehensive literature review.
&lt;/a&gt;&lt;/p&gt;Surg Obes Relat Dis (2016)&lt;/div&gt;'>[64]</a>
Aging. The ability to make vitamin D in the skin during sun exposure decreases with age, by an amount of 13% per decade, according to one study comparing vitamin D synthesis after a single incidence of sun exposure in younger and older adults.<a href="#ref-65" id="ref-link-65" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Jenna R Chalcraft, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32727044" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women
&lt;/a&gt;&lt;/p&gt;Nutrients (2020 Jul 27)&lt;/div&gt;'>[65]</a>

What are some of the factors that can increase the risk of having a vitamin D deficiency?

The American Academy of Pediatrics (AAP) recommends that exclusively breastfed infants receive 400 IU (10 μg) a day of vitamin D for the first year of life and that toddlers and older children receive 600 IU (15 μg) a day. This is to prevent the consequences of <a href="/conditions/vitamin-d-deficiency/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Vitamin D Deficiency&lt;/h6&gt;&lt;p&gt;Vitamin D deficiency occurs when a person isn't getting enough vitamin D to stay healthy. This deficiency can result in a loss of bone density, leading to osteoporosis and fractures. Severe vitamin D deficiency can cause other diseases such as rickets and osteomalacia.&lt;/p&gt;&lt;/div&gt;">vitamin D deficiency</a> (particularly rickets), since human milk and most foods are inadequate sources of vitamin D, and the majority of infants and children do not get enough sun exposure to produce all the vitamin D that they need.<a href="#ref-60" id="ref-link-60" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wagner CL, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18977996" target="\_blank" rel="noopener noreferrer"&gt;Prevention of rickets and vitamin D deficiency in infants, children, and adolescents.
&lt;/a&gt;&lt;/p&gt;Pediatrics (2008-Nov)&lt;/div&gt;'>[60]</a> 
There are two important exceptions to this vitamin D supplementation recommendation. First, formula-fed infants that consume at least 32 oz of formula per day usually do not require supplementation, since most formulas are fortified with vitamin D. Second, if a lactating parent is supplementing with 6400 IU (160 μg) a day of vitamin D, studies find that enough vitamin D passes into the breastmilk to negate the need for direct infant supplementation.<a href="#ref-89" id="ref-link-89" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Corsello A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/35742074" target="\_blank" rel="noopener noreferrer"&gt;Different Vitamin D Supplementation Strategies in the First Years of Life: A Systematic Review.
&lt;/a&gt;&lt;/p&gt;Healthcare (Basel) (2022-Jun-01)&lt;/div&gt;'>[89]</a>
Vitamin D toxicity in children is rare, but not impossible. The estimated tolerable upper limits set by the AAP are 1000 IU (25 μg) a day for children 0–1 years old, 2500 IU (62.5 μg) a day for children 1–3 years old, 3000 IU (75 μg) a day for children 4–8 years old, and 4000 IU (100 μg) a day for children nine years and older. Toxicity usually occurs with accidental ingestion of large doses of supplemental vitamin D, as found in a case series of 7 children who consumed between 266,000 and 800,000 IU (6650–20000 μg) a day due to erroneously manufactured supplements.<a href="#ref-90" id="ref-link-90" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kara C, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24298009" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D intoxication due to an erroneously manufactured dietary supplement in seven children.
&lt;/a&gt;&lt;/p&gt;Pediatrics (2014-Jan)&lt;/div&gt;'>[90]</a>
Vitamin D supplementation in infants and children should be discussed with a clinician, especially if there are concerns about vitamin D serum levels. A clinician can order blood work to better guide any supplement decisions.

Should vitamin D supplements be given to infants and children?

<img src="https://examine.nyc3.digitaloceanspaces.com/files/images/XboiyVaIp2tTVqBOlUdt19etfKzSyFZGI6OJnoiW.png" alt="image">
Vitamin D exerts its effects by binding to and activating the vitamin D receptor (VDR). Upon binding vitamin D, the VDR functions as a transcription factor, regulating the activity of over 1,000 different genes.<a href="#ref-14" id="ref-link-14" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Maestro MA, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/27454349" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D receptor 2016: novel ligands and structural insights.
&lt;/a&gt;&lt;/p&gt;Expert Opin Ther Pat (2016-Nov)&lt;/div&gt;'>[14]</a> This “genomic” action of vitamin D tends to be slower-acting, requiring the synthesis of new mRNA and proteins to take effect. 
Vitamin D also works through “non-genomic” mechanisms, causing rapid activation of various signaling pathways within the cell. Although VDRs have been identified on cell membranes, it isn’t currently known whether the more rapid, non-genomic action of vitamin D occurs through membrane-associated vitamin D receptors or a different cellular receptor.<a href="#ref-15" id="ref-link-15" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Zmijewski MA, Carlberg C. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32654294" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D receptor(s): In the nucleus but also at membranes?
&lt;/a&gt;&lt;/p&gt;Exp Dermatol (2020-Sep)&lt;/div&gt;'>[15]</a>
Although the most commonly associated effects of vitamin D on the body are associated with bone metabolism, the almost ubiquitous presence of VDRs in cells and tissues throughout the body indicates that vitamin D can affect a wide range of physiological processes.<a href="#ref-16" id="ref-link-16" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Carlberg C. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/35405966" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D and Its Target Genes.
&lt;/a&gt;&lt;/p&gt;Nutrients (2022-Mar-24)&lt;/div&gt;'>[16]</a> The additional effects of vitamin D on the body include, but aren’t limited to, the following:<a href="#ref-17" id="ref-link-17" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Wang W, Li Y, Meng X. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36820164" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D and neurodegenerative diseases.
&lt;/a&gt;&lt;/p&gt;Heliyon (2023-Jan)&lt;/div&gt;'>[17]</a>
<ul>
<li>Anticancer effects (promotion of cell death or suppressing proliferation in cancer cells)</li>
<li>Brain development<a href="#ref-18" id="ref-link-18" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Eyles DW, Burne TH, McGrath JJ. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22796576" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease.
&lt;/a&gt;&lt;/p&gt;Front Neuroendocrinol (2013-Jan)&lt;/div&gt;'>[18]</a></li>
<li>Cell differentiation<a href="#ref-19" id="ref-link-19" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Fernandes de Abreu DA, Eyles D, Féron F. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/19545951" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D, a neuro-immunomodulator: implications for neurodegenerative and autoimmune diseases.
&lt;/a&gt;&lt;/p&gt;Psychoneuroendocrinology (2009-Dec)&lt;/div&gt;'>[19]</a><a href="#ref-20" id="ref-link-20" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chen S, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/17641030" target="\_blank" rel="noopener noreferrer"&gt;Modulatory effects of 1,25-dihydroxyvitamin D3 on human B cell differentiation.
&lt;/a&gt;&lt;/p&gt;J Immunol (2007-Aug-01)&lt;/div&gt;'>[20]</a></li>
<li>Anti-inflammatory effects<a href="#ref-21" id="ref-link-21" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ma Y, Johnson CS, Trump DL. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/26827961" target="\_blank" rel="noopener noreferrer"&gt;Mechanistic Insights of Vitamin D Anticancer Effects.
&lt;/a&gt;&lt;/p&gt;Vitam Horm (2016)&lt;/div&gt;'>[21]</a></li>
<li>Antioxidant effects<a href="#ref-22" id="ref-link-22" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Chen L, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/30907059" target="\_blank" rel="noopener noreferrer"&gt;1,25-Dihydroxyvitamin D exerts an antiaging role by activation of Nrf2-antioxidant signaling and inactivation of p16/p53-senescence signaling.
&lt;/a&gt;&lt;/p&gt;Aging Cell (2019-Jun)&lt;/div&gt;'>[22]</a></li>
<li>Antibacterial effects (through vitamin D’s effects on immune cells, and its promotion of the expression of genes encoding antimicrobial peptides)<a href="#ref-23" id="ref-link-23" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Prietl B, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/23857223" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D and immune function
&lt;/a&gt;&lt;/p&gt;Nutrients (2013 Jul 5)&lt;/div&gt;'>[23]</a></li>
<li>Blood vessel protection<a href="#ref-24" id="ref-link-24" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Enkhjargal B, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/28825325" target="\_blank" rel="noopener noreferrer"&gt;Vitamin D attenuates cerebral artery remodeling through VDR/AMPK/eNOS dimer phosphorylation pathway after subarachnoid hemorrhage in rats.
&lt;/a&gt;&lt;/p&gt;J Cereb Blood Flow Metab (2019-Feb)&lt;/div&gt;'>[24]</a></li>
<li>Nervous system health</li>
<li>Calcium regulation</li>
</ul>

How does vitamin D work?

Vitamin D

Immunity & Infectious Disease

Unit conversions; USA: National Institutes of Health Office of Dietary Supplements, cited 2024 Mar 27

Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D.

Meal conditions affect the absorption of supplemental vitamin D3 but not the plasma 25-hydroxyvitamin D response to supplementation

Vitamin D: Fact Sheet for Professionals; USA: National Institutes of Health Office of Dietary Supplements; cited March 2024; last updated 18 Sep 2023

Vitamins, supplements and nutrition in pregnancy; UK: National Health Service, cited March 2024, updatedSeptember 2023

Therapeutic regimens for vitamin D deficiency in postmenopausal women: a systematic review.

Development of Vitamin D Toxicity from Overcorrection of Vitamin D Deficiency: A Review of Case Reports.

Vitamin D Fact sheet for consumers. National Institutes of Health (NIH) Office of Dietary Supplements (ODS) updated 2022 Nov 8; cited 2023 May 24

Increased incidence of nephrolithiasis (N) in lifeguards (LG) in Israel.

Long-term supplementation with 3200 to 4000 IU of vitamin D daily and adverse events: a systematic review and meta-analysis of randomized controlled trials.

Monthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline: A Randomized Clinical Trial

The Effects of Four Doses of Vitamin D Supplements on Falls in Older Adults : A Response-Adaptive, Randomized Clinical Trial

Adverse Effects of High-Dose Vitamin D Supplementation on Volumetric Bone Density Are Greater in Females than Males

Vitamin D receptor 2016: novel ligands and structural insights.

Vitamin D receptor(s): In the nucleus but also at membranes?

Vitamin D and Its Target Genes.

Vitamin D and neurodegenerative diseases.

Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease.

Vitamin D, a neuro-immunomodulator: implications for neurodegenerative and autoimmune diseases.

Modulatory effects of 1,25-dihydroxyvitamin D3 on human B cell differentiation.

Mechanistic Insights of Vitamin D Anticancer Effects.

1,25-Dihydroxyvitamin D exerts an antiaging role by activation of Nrf2-antioxidant signaling and inactivation of p16/p53-senescence signaling.

Vitamin D and immune function

Vitamin D attenuates cerebral artery remodeling through VDR/AMPK/eNOS dimer phosphorylation pathway after subarachnoid hemorrhage in rats.

Seasonal variation in 25(OH)D at Aberdeen (57°N) and bone health indicators--could holidays in the sun and cod liver oil supplements alleviate deficiency?

Vitamin A hepatotoxicity in multiple family members.

Acute fish liver intoxication: report of three cases.

The vitamin A content and toxicity of bear and seal liver.

Vitamin D toxicity, policy, and science

Dietary fat increases vitamin D-3 absorption

Vitamin D metabolism and function in the skin

Ultraviolet radiation and the skin: Photobiology and sunscreen photoprotection

The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial

Layer Thickness of SPF 30 Sunscreen and Formation of Pre-vitamin D

Sunscreens block cutaneous vitamin D production with only a minimal effect on circulating 25-hydroxyvitamin D

Application of sunscreen--theory and reality

The effect of sunscreen on vitamin D: a review

Sunscreen photoprotection and vitamin D status

Fractional Sunburn Threshold UVR Doses Generate Equivalent Vitamin D and DNA Damage in Skin Types I-VI but with Epidermal DNA Damage Gradient Correlated to Skin Darkness

Dietary Reference Intakes for Calcium and Vitamin D

Colour Counts: Sunlight and Skin Type as Drivers of Vitamin D Deficiency at UK Latitudes

Meeting Vitamin D Requirements in White Caucasians at UK Latitudes: Providing a Choice

Sunlight regulates the cutaneous production of vitamin D3 by causing its photodegradation

Fast simulation tool for ultraviolet radiation at the earth's surface

Holick's rule and vitamin D from sunlight

Estimated equivalency of vitamin D production from natural sun exposure versus oral vitamin D supplementation across seasons at two US latitudes

Calculated ultraviolet exposure levels for a healthy vitamin D status

Vitamin D intakes in North America and Asia-Pacific countries are not sufficient to prevent vitamin D insufficiency.

Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin

Determination of vitamin D in relation to body mass index and race in a defined population of black and white women.

Vitamin D: The "sunshine" vitamin

Vitamin D deficiency

Prevalence and correlates of vitamin D deficiency in US adults

Vitamin D deficiency: A single centre analysis of patients from 136 countries

Letter to Veugelers, P.J. and Ekwaru, J.P., A statistical error in the estimation of the recommended dietary allowance for vitamin D. Nutrients 2014, 6, 4472-4475; doi:10.3390/nu6104472

A statistical error in the estimation of the recommended dietary allowance for vitamin D

 Dietary Reference Intakes for Calcium and Vitamin D (2011). The National Academies Press; Washington, D.C..

Geographic location and vitamin D synthesis.

Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness.

Prevention of rickets and vitamin D deficiency in infants, children, and adolescents.

Vitamin D status in gastrointestinal and liver disease.

Intestinal absorption of vitamin D: a systematic review

Vitamin D Metabolism in Bariatric Surgery.

Vitamin D status and supplementation before and after bariatric surgery: a comprehensive literature review.

Vitamin D Synthesis Following a Single Bout of Sun Exposure in Older and Younger Men and Women

Healthline: The Best Vegan Sources of Vitamin D

 Vitamin D in foods: an evolution of knowledge. In: Vitamin D (4th Edition). New York, NY: Elsevier. p. 41-77

Including food 25-hydroxyvitamin D in intake estimates may reduce the discrepancy between dietary and serum measures of vitamin D status.

Association of vitamin D status with serum androgen levels in men

Effect of vitamin D supplementation on testosterone levels in men

Vitamin D Fact sheet for health professionals. MedlinePlus. National Institutes of Health (NIH) Office of Dietary Supplements (ODS). Updated 2022 Aug 12; cited 2023 May 22

Effects of orlistat on fat-soluble vitamins in obese adolescents.

Drug-vitamin D interactions: a systematic review of the literature

Association of glucocorticoid use and low 25-hydroxyvitamin D levels: results from the National Health and Nutrition Examination Survey (NHANES): 2001-2006.

Hypercalcaemia following vitamin D and thiazide therapy in the elderly.

Hazards of treating osteoporosis and hypertension concurrently with calcium, vitamin D, and distal diuretics

The urgent need to recommend an intake of vitamin D that is effective.

The effect of vitamin D and frailty on mortality among non-institutionalized US older adults.

Vitamin D supplementation for prevention of mortality in adults

Association between vitamin D supplementation and mortality: systematic review and meta-analysis

Latitude is significantly associated with the prevalence of multiple sclerosis: a meta-analysis.

Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins.

Vitamin D supplementation in multiple sclerosis: an expert opinion based on the review of current evidence.

Vitamin D Supplementation in Multiple Sclerosis: A Critical Analysis of Potentials and Threats

The beneficial role of vitamin D in Alzheimer's disease.

1α,25-dihydroxyvitamin D3 and resolvin D1 retune the balance between amyloid-β phagocytosis and inflammation in Alzheimer's disease patients.

Effects of vitamin D supplementation on cognitive function and blood Aβ-related biomarkers in older adults with Alzheimer's disease: a randomised, double-blind, placebo-controlled trial

The Efficacy of Vitamin D Supplementation in Patients With Alzheimer's Disease in Preventing Cognitive Decline: A Systematic Review.

Different Vitamin D Supplementation Strategies in the First Years of Life: A Systematic Review.

Vitamin D intoxication due to an erroneously manufactured dietary supplement in seven children.

Vitamin D and Male Erectile Function: An Updated Review.

Vitamin D and depression

Vitamin D: A Narrative Review Examining the Evidence for Ten Beliefs

Vitamin D supplementation to reduce depression in adults: meta-analysis of randomized controlled trials

Vitamin D and depression: a systematic review and meta-analysis comparing studies with and without biological flaws

Efficacy of vitamin D supplementation in major depression: A meta-analysis of randomized controlled trials

Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical Trial

Retraction of Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical Trial. J Nutr 2016;146(2):243-8.

A randomized controlled trial of vitamin D supplementation on perinatal depression: in Iranian pregnant mothers

Vitamin D

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