The skincare industry generated over $5.6 billion in sales in 2018 alone. The brands marketed as “natural” led the pack and were the top contributors to market growth.

Plant oils, extracts, and supplements have received a lot of attention as potential natural alternatives to replace commercial sunscreen products. So are there any out there that work? Let's find out.

A primer on ultraviolet radiation

Excessive unprotected exposure to solar radiation can promote skin aging and skin cancer. Especially dangerous is the ultraviolet (UV) spectrum,^{[1][2][3][4][5]} whose wavelength is shorter than that of visible light but longer than that of X-rays.

Sun radiation wavelengths in nanometers

The main culprits are UVA and UVB radiation; UVA accounting for 95% of UV rays reaching Earth’s surface and UVB for 5%. Together, they can induce sunburns, DNA damage, and accelerate skin aging.^[1][3]

When used correctly and consistently, sunscreens can mitigate sun-induced skin aging (i.e., photoaging) and reduce the risk of skin cancer.

Can plant oils protect me?

In general, it's recommended that you use a broad-spectrum sunscreen (i.e., UVA + UVB protection) with a sun protection factor (SPF) of 30, at minimum, or 40 if you burn easily. So, are natural plant oils up for the challenge?

In short, not really. At least not on their own.

When tested for protection against just UVB radiation, many plant oils provide an SPF of <8.^[6] These oils can be incorporated into commercial sunscreen products to help the overall SPF rating, but on their own, they are insufficient for UV protection.

Reliability can also be an issue if plant-based formulas are made at home. Sunscreens are formulated using specific ingredients in specific amounts in addition to employing manufacturing methods to help ensure these UV-protective ingredients are evenly distributed throughout the sunscreen. This process is challenging to replicate at home.

A note of caution — some of these plant oils can cause allergic reactions or skin irritation.^[7][8] These reactions can range from minor to severe.

Sun protection factor (SPF) values of plant oils

Adapted from Kaur and Saraf. Pharmacognosy Res. 2010.^[6]

Note that the above chart only takes into account protection against UVB radiation. In some cases, when SPF against both UVB and UVA is measured, these values drop even lower. For example, coconut oil offers an SPF of 7 for just UVB^[6] but an SPF of ≤1 against UVA + UVB.^[9]

Plant oils alone should not be used to wholly replace sunscreen, as they do not provide adequate protection. However, they may be used as an ingredient in some sunscreens to boost the overall SPF rating.

Can supplements protect me?

Cocoa

When using specially processed high-flavanol cocoa powders or chocolate, three RCTs (almost all in females with Fitzpatrick skin types 2 or 3) saw a modest improvement in the skin’s ability to resist UV damage after 6 weeks of supplementation.^[10][11][12]

The results are promising and fairly consistent across the existing trials. Consider this supplement “one to watch” as further trials get published.

Fitzpatrick skin type scale

Polypodium leucotomos

In both animal and human trials, Polypodium leucotomos (P. leucotomos) has demonstrated an ability to reduce UV-caused skin cell damage, DNA damage, and oxidative stress.^[13] In just the human trials, both short (<1 week)^{[14][15][16][17][18][19]} and long-term (1- to 3-month) trials^[20][21][22] have seen consistent results.

One limitation is that nearly all of these studies were conducted in people with Fitzpatrick skin types 1–3. The effects of P. leucotomos on skin types 4–6 are understudied at the moment.

A note of caution — the estimated SPF protection of P. leucotomos is ≈4.^[19] This is well below the recommended level of at least 30. It should not be used as a sunscreen replacement.

Astaxanthin

Astaxanthin, a powerful antioxidant, may help to reduce DNA damage caused by UV radiation.^[23][24]. Yet, the research to date has been spotty and not very high quality.^{[23][25][26][27]} Better research is needed before firm conclusions can be made about its effectiveness.

Rosemary and Grapefruit Extract

Two promising human trials have examined a combination of rosemary and grapefruit extracts for UV protection.

The first was a small pilot trial in 10 subjects^[28] and the second was a follow-up study that randomized 90 subjects.^[29] In both trials, the combination was able to increase UV tolerance and reduce markers of oxidative damage in the skin.

Despite the promising results, firm conclusions can't yet be drawn on such limited data.

Vitamin E

While animal and cell studies have indicated vitamin E is a candidate for UV protection,^[30][31] human trials have given mixed (but promising) results for both topical applications^{[32][33][34][35][36]} and when orally supplemented.^{[37][38][39][40][41]}

Another wrinkle — many studies have tested vitamin E as a part of a multi-ingredient formula, making it very difficult to say what the effect of this vitamin used alone might be.

Supplements alone should not be used to wholly replace sunscreen. Of the supplements reviewed above, Polypodium leucotomos has the strongest evidence indicating it can deliver a small amount of UV protection.

What about sunscreens labeled as “natural” or “clean”?

In the US, the terms “clean” and “natural” are not defined or regulated when it comes to skincare products.^[42] The inclusion of these terms on the label does not offer any assurances that the product is safer for consumers compared to products that don’t contain these labels.

However, there are two natural sunscreen ingredients that have a proven track record — zinc oxide and titanium dioxide. Often referred to as physical chemical barriers (aka inorganic chemical barriers or mineral sunscreens), these naturally occurring compounds function by reflecting and dissipating UV rays.

Bottom line

The terms “clean” and “natural” are unregulated in the US and don’t guarantee any advantage over traditional sunscreen products. However, zinc oxide and titanium dioxide are two naural ingredients that have proven UV-protective abilities.

There is no plant oil or extract that can replace sunscreen. Plant oils may be combined with sunscreens to boost their overall efficacy, but beware that they can also cause allergic skin reactions or irritations in some people.

There is no supplement that can replace sunscreen. Of the ones studied, Polypodium leucotomos shows the greatest promise for possibly acting synergistically when used in tandem with sunscreen or other sun protection methods.

Your body can produce vitamin D when the skin is exposed to ultraviolet B (UVB) rays.^[43] Yet it is these rays that sunscreens are designed to primarily block.^[44] So will using sunscreen tank your vitamin D levels?

Sunscreen and vitamin D production

Sunscreen can decrease vitamin D production under both controlled laboratory testing and real-world conditions.^[45][46] 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).^[47][48][49]

Yet, the amount to which sunscreen decreases vitamin D production appears to be small — a counterintuitive finding.^[50] How could this be? Two factors have been proposed as possible explanations:^[50]

1. 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.

2. 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.

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.