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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.
Vitamin D is most often used for
Last Updated:November 30, 2023
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.
Is there a difference between Vitamin D2 and Vitamin D3?
What are some dietary sources of vitamin D3?
Supplemental vitamin D is associated with a range of benefits, including improved immune health, bone health, and well-being. Supplementation may also reduce the risk of cancer mortality, diabetes, and multiple sclerosis. Vitamin D is often taken for depression 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.
Can vitamin D cure depression?
Can vitamin D supplementation help with symptoms of depression?
Can vitamin D status affect testosterone levels?
Is there a link between vitamin D levels and all-cause mortality?
Can vitamin D supplementation improve symptoms of multiple sclerosis?
Can vitamin D supplementation help with treatment or prevention of Alzheimer’s disease?
Can vitamin D supplementation help with the treatment or prevention of other neurodegenerative diseases?
Extremely high doses of vitamin D can lead to vitamin D toxicity, which causes hypercalcemia (excess calcium in the blood), leading to and array of health problems[1]
Vitamin D supplementation may also have risks independent of vitamin D toxicity. A few trials on older adults have found that vitamin D increased the risk of falls,[2][3] and one study observed a decrease in bone mineral density among women taking high doses of vitamin D.[4]
Do vitamin D supplements interact with any medications?
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.[5] 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.[6]
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.[7] The additional effects of vitamin D on the body include, but aren’t limited to, the following:[8]
How much fat do I need to absorb vitamin D?
Does sunscreen decrease vitamin D?
How much sun do I need for vitamin D production?
Who needs to supplement vitamin D?
What are some of the factors that can increase the risk of having a vitamin D deficiency?
Can I get enough vitamin D3 from diet and sun exposure alone, or do I need to take supplements?
How much vitamin D should I take?
Can I get too much vitamin D?
Should vitamin D supplements be given to infants and children?
Full page update
We updated this page and it's database with the newest meta-analyses.