Sunscreen can block the light skin uses to make vitamin D, yet real-life studies find little effect on blood levels. The lab and the beach don't agree. Neale and colleagues laid out both halves in a 2019 review in the British Journal of Dermatology. A field trial in holiday sun that year sided with real life.
Plenty of posts say sunscreen blocks the light that makes vitamin D, so daily use must leave you short. Others promise a natural SPF from food. Tomato paste and astaxanthin capsules top their lists, and I'll stick to what the trials measured. The American Academy of Dermatology (AAD) points people to food for vitamin D, and the official intake numbers already assume minimal sun.
We make tallow balms and no sunscreen, so I've got no screen to sell you here. A balm is not a screen and won't make vitamin D. For the evening after a day outside, once the sunscreen's washed off, I'd reach for Bare Silk ($34, as of October 5, 2026), the Unscented original. It's cosmetic care, not a treatment. Your provider's plan comes first. Our post on tallow and SPF covers what a balm can't do about the sun, and what to use instead.
Does sunscreen block vitamin D?
Under a lab lamp it does, and by a wide margin. Neale and colleagues pulled 76 studies, published from 1970 to late 2017, for their 2019 review. Four were experiments under artificial UV, and the other 72 looked at people in daily life, three of them as field trials. In the experiments, sunscreen "considerably abrogated" the vitamin D the lamps would have made. That's lab talk for largely cancelled. The review also notes that those lamps don't put out light like the sun's.
Real life read differently. The two randomized field trials found no effect of daily sunscreen on blood levels, though the screens they used were moderate, around SPF 16. Most observational studies found either no link or higher vitamin D in people who said they wore sunscreen. The authors concluded there's little evidence sunscreen lowers vitamin D in real-life use, and that vitamin D worries shouldn't override skin cancer advice. They flagged a gap, too. Nobody had yet run a trial with the high-SPF screens now widely recommended.
What did a sunny week in Tenerife show?
Young and colleagues took the question into hard sun in a 2019 study. Healthy Polish volunteers spent a one-week holiday in Tenerife, at 28 degrees north, while the UV index ran very high. Two groups of 20 got an SPF 15 sunscreen and advice on applying it. One screen had low UVA protection, the other high. A third group of 22 used sunscreen however they liked, and 17 people who didn't travel served as a comparison at 51.8 degrees north.
Both test screens stopped sunburn, while burns showed up in the group that used sunscreen their own way. Vitamin D rose anyway. Blood levels climbed 19.0 nmol/L in the high UVA group and 13.0 in the low UVA group, and both rises were significant. The free-choice group rose most, by 28.0, and that's the group where the burns turned up. The people who didn't travel slipped 2.5.
The authors' reading is that sunscreen can stop a burn and still allow vitamin D synthesis. The high UVA screen allowed more of it. At the same SPF 15, they explain, a screen with more UVA protection lets more UVB through by default, and that's the band skin uses to make vitamin D.
Why doesn't daily life match the lab?
One piece of the gap is how much sunscreen people put on. The AAD says many people apply only about 20 to 50% of the amount needed to reach the SPF on the label. That's a big shortfall. For an adult's body, the academy's minimum is about an ounce, roughly a shot glass, with at least a teaspoon for the face.
The NIH fills in the rest. Its Office of Dietary Supplements says sunscreens of SPF 8 or more appear to block the UV that makes vitamin D. In practice, though, people miss skin and don't reapply on schedule. Its fact sheet concludes that skin "probably synthesizes some vitamin D" even with the amounts people use. The AAD's answer to the shortfall is more sunscreen, the full ounce reapplied about every two hours outdoors, with food covering vitamin D.
Where should vitamin D come from?
The AAD recommends that healthy adults get enough vitamin D from foods naturally rich in it or fortified with it. Sun exposure and indoor tanning don't make its list. There's no safe level of UV, the academy says, that allows maximum vitamin D synthesis without raising skin cancer risk.
The official numbers are built the same way. The RDAs assume people get minimal sun, the NIH's Office of Dietary Supplements explains. Its fact sheet calls UV exposure "the most preventable cause of skin cancer" and says limiting sun on skin is prudent. From age 1 through 70, the RDA is 15 mcg (600 IU) a day. Past 70, it's 20 mcg (800 IU). Here's how far one serving goes, according to the food table in the same fact sheet.
| Food | Serving | Vitamin D |
|---|---|---|
| Cod liver oil | 1 tablespoon | 1,360 IU |
| Rainbow trout, farmed, cooked | 3 ounces | 645 IU |
| Sockeye salmon, cooked | 3 ounces | 570 IU |
| White mushrooms, UV-exposed | 1/2 cup, sliced | 366 IU |
| Milk, 2%, fortified | 1 cup | 120 IU |
Supplements are the other route. Both D2 and D3 raise blood levels, the fact sheet says, though D3 raises them more and holds them longer. If you think you're low, the blood test for 25-hydroxyvitamin D answers that, and your doctor's the one to order it and set any dose.
Can food give you a natural SPF?
Here's what a randomized trial measured. In a 2011 trial by Rizwan and colleagues, 20 women were randomized to tomato paste or a control for 12 weeks. The paste group ate 55 g a day in olive oil, carrying 16 mg of lycopene. Controls took the olive oil alone. Before and after, the team measured how much UV it took to redden skin. One reading, taken with a reflectance instrument, rose in the tomato group to 36.6 mJ/cm² against 23 in the control group. The minimal erythema dose, read by eye, didn't differ significantly between groups.
The abstract gives no SPF figure. In the US, sunscreens are regulated as drugs, the FDA notes. Each must be tested for how much UV it takes to burn skin wearing it, compared with bare skin, and the SPF comes from that comparison. No food carries an SPF rating. A tomato-heavy lunch is still lunch, and it doesn't replace the screen you put on before heading out.
On a beach day, I save the balm for last. Once the sunscreen's washed off at night, intact skin that feels tight after a day outside takes a thin layer of the unscented jar I named up top.
Start with Bare Silk ($34), five ingredients and sixty days to disagree.
Questions we hear
Does sunscreen cause vitamin D deficiency?
The real-life evidence puts the risk low, according to a 2019 review in the British Journal of Dermatology. Neale and colleagues found sunscreen cut vitamin D production under lab lamps, while field trials of daily use found no effect on blood levels. Those trials used screens around SPF 16. The higher SPFs now widely recommended hadn't been tested yet, and the NIH says skin probably still makes some vitamin D at the amounts people apply.
How much vitamin D do adults need?
The NIH's Office of Dietary Supplements lists an RDA of 15 mcg (600 IU) a day for adults through age 70. From 71 on, it's 20 mcg (800 IU). Pregnancy and breastfeeding stay at 15 mcg, and those numbers assume minimal sun, so they're meant to come from food and supplements. For adults, the upper limit the fact sheet lists is 100 mcg (4,000 IU) a day.
Can your skin make vitamin D through a window?
No. UVB, the part of sunlight skin uses to make vitamin D, doesn't pass through glass. A sunny window seat won't make any, the NIH says. Its consumer fact sheet adds that clouds and smog cut how much vitamin D skin makes, and so do older age and darker skin.
Is there a natural SPF in food?
No food carries an SPF, because an SPF comes from testing a sunscreen product on skin. In the US, sunscreens are regulated as drugs, and the test measures how much UV it takes to burn skin wearing the product against bare skin. Food trials measure smaller things. In a 2011 trial by Rizwan and colleagues, 12 weeks of daily tomato paste moved one instrument reading of skin redness, while the visual redness threshold didn't differ significantly from the control group.
What vitamin D blood level is adequate?
The test measures 25-hydroxyvitamin D, which the NIH calls the main indicator of vitamin D status. For most people, 50 nmol/L (20 ng/mL) or above is adequate. Below 30 nmol/L (12 ng/mL) is too low and might weaken bones, the consumer fact sheet says. That's the number to read on your lab report.
Go deeper
The beef tallow for skin guide covers what a balm does and doesn't do on skin. Oil cleansing then tallow covers taking sunscreen off at night. How to use a tallow balm is the place to start if the jar's new to you, and fatty acids in tallow explains what's in the fat itself. The rest of the sun set: is sunscreen bad for you weighs the trials, mineral vs chemical sunscreen picks a filter, and tallow and sunburn is the read for the day the sunscreen was skipped.
Sources
- Young and colleagues (2019). Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. British Journal of Dermatology 181(5):1052 to 1062, record at King's College London.
- Rizwan and colleagues (2011). Tomato paste rich in lycopene protects against cutaneous photodamage in humans in vivo: a randomized controlled trial. British Journal of Dermatology 164(1):154 to 162, University of Manchester record.
- Neale and colleagues (2019). The effect of sunscreen on vitamin D: a review. British Journal of Dermatology 181(5):907 to 915, abstract page read on the publisher's site.
- NIH Office of Dietary Supplements (2026). Vitamin D: fact sheet for health professionals, read October 5, 2026. NIH.
- NIH Office of Dietary Supplements (2026). Vitamin D: fact sheet for consumers, page read October 5, 2026. NIH.
- American Academy of Dermatology Association (2025). Vitamin D, the academy's recommendations page, last updated February 11, 2025. AAD.
- American Academy of Dermatology Association (2025). Sunscreen FAQs, the academy's public answers page, last updated February 11, 2025. AAD.
- US Food and Drug Administration (2026). Sunscreen: how to help protect your skin from the sun, content current as of September 10, 2026. FDA consumer page.
Brian is the founder of Craft Tallow, a small-batch tallow skincare line shipped from Cottonwood Heights, Utah, built on 100% grass-fed suet. Questions? Reply to any email from us; it lands with him.