Vitamin D and Sunlight: How the Skin Makes It, Season, Latitude, Skin Colour and Sun Safety
How skin makes vitamin D from sunlight, and how season, latitude, skin color, age and sunscreen change it, balanced against what health bodies say about skin cancer.
Content last updated . This page has not been medically reviewed.
The balance, stated first
Sunburn raises skin cancer risk, and the NHS (UK) says there is no safe or healthy way to get a tan; it advises aiming for a balance between protecting skin and getting vitamin D from sunlight. [1] The US National Cancer Institute says people of all ages and skin tones should limit time in the sun and avoid tanning beds, and that skin cancer can occur in all skin tones. [2] This page explains the science of vitamin D and the sun. It does not tell anyone how many minutes to spend outdoors: MedlinePlus says the amount made varies greatly from person to person. [3]How skin makes vitamin D
Vitamin D is produced by the skin after it is exposed to UVB radiation from sunlight. [4] The raw material is provitamin D3 (7-dehydrocholesterol) in the skin's outer layer, where UV light forms previtamin D3. [5] Before the body can use it, the liver changes vitamin D into 25-hydroxyvitamin D, the form most blood tests measure. [6] MedlinePlus says the body makes it when bare skin, without sunscreen, is exposed to sunlight outdoors. [6]Evidence labels: established, modelled estimate, observational finding, mixed, insufficient evidence. A study amount is not advice. For the vitamin itself see Vitamin D.
What changes how much is made
| Factor | What the source says | Label |
|---|---|---|
| Season and latitude (UK) | From about late March or early April to the end of September most people can make the vitamin D they need; between October and early March the sun is not strong enough [7] | Established (official advice) |
| Latitude and season (model) | A 2020 modelling study found 400 IU a day equivalent was achievable through casual midday sun, with no sunburn (erythema) risk, at all latitudes for some of the year and all year at low latitudes. 4,000 IU a day was not achievable in a lunchtime hour for much of the globe and year [8] | Modelled estimate, not a trial |
| Skin color | Melanin absorbs UV radiation. Vitamin D deficiency is most prevalent in darkly pigmented people living in low-UV environments [9]. The NHS says dark skin may not make enough from sunlight and to consider a supplement all year [7] | Observational plus official advice |
| Age | In skin samples from people aged 8 to 92, the capacity to make previtamin D3 fell by more than half in 77- and 82-year-olds compared with 8- and 18-year-olds [5] | Lab study of skin samples |
| Cloud, shade, clothing | MedlinePlus: cloudy days, shade and dark skin cut production. The NHS says people who cover most skin outdoors may not make enough [3][7] | Official advice |
| Being indoors | Not often outdoors (frail, housebound, care home) is on the NHS list of people advised to take a supplement all year [7] | Official advice |
Sunscreen and vitamin D
Sunscreen reduces vitamin D production in laboratory studies. [4] What happens in daily life is less clear:| Study | What it found | Label |
|---|---|---|
| 2019 systematic review (4 experimental studies, 3 field trials, 69 observational studies) | Sunscreen strongly reduced vitamin D production under artificial UV; the two randomized field trials, using about SPF 16, found no effect; most observational studies found no association or higher levels with self-reported use. There were no trials of the high-SPF sunscreens now widely recommended [10] | Mixed |
| 2025 Sun-D Trial (639 Australian adults, about 1 year) | Daily SPF 50+ on days the UV index was forecast at 3 or higher gave 25(OH)D 5.2 nmol/L lower than discretionary use. Deficiency (under 50 nmol/L) was 45.7% versus 36.9%. The authors wrote that regular sunscreen users may need vitamin D supplementation [4] | Randomized, open-label |
The NHS still advises at least factor 30 sunscreen, shade and clothing, and says not to rely on sunscreen alone. [1] Both findings can be true: sunscreen guards against skin cancer, and heavy daily use may lower vitamin D levels. Do not drop sunscreen on this basis; ask a clinician whether your vitamin D intake is adequate.
Who needs extra care
- Babies and children: the NHS says to keep babies under 6 months out of direct sunlight and that children's skin is much more sensitive; all children under 5 are advised to take vitamin D supplements in the UK. [1] See Vitamin D and K for newborns and Children and teens.
- Pale skin, freckles, red or fair hair, many moles, or skin conditions: the NHS says to take extra care in the sun. [1]
- People with dark skin: low sun-made vitamin D and skin cancer risk can both apply; NCI says skin cancer occurs in dark skin too. [2]
Intake from food and supplements
When sun is limited, the NHS advises everyone to consider a daily 10 mcg supplement in autumn and winter, and all year for higher-risk groups. [7] The Endocrine Society found no trial evidence supporting routine 25(OH)D testing in the general population. [11] See Vitamin D deficiency and testing and RDA, AI, DV and UL. Talk to a clinician or pharmacist about the right amount for you; you cannot overdose from sunlight, but supplements can. [7]Frequently asked questions
Can I get all my vitamin D from the sun?
In the UK, most people can from about late March to September, not October to early March. Skin color, clothing, age and sunscreen change this. [7]
Does sunscreen cause vitamin D deficiency?
A 2019 review found little evidence it does in real life with moderate SPF, but a 2025 trial found lower levels with daily SPF 50+. Neither is a reason to skip skin protection; ask a clinician about supplements. [10][4]
Does dark skin need more sun?
Melanin absorbs UV, so dark skin makes less vitamin D at the same exposure, and the NHS suggests considering a supplement all year. Skin cancer still occurs in dark skin. [9][7][2]
Can I overdose from sunlight?
The NHS says you cannot overdose on vitamin D through sunlight, but you can burn, so cover up or protect your skin. [7]
Do sunbeds make vitamin D safely?
We did not search for or read evidence on sunbeds as a vitamin D source, so no claim is made. NCI says the sun, sunlamps and tanning booths all give off UV radiation that can damage skin and lead to skin cancer, and advises avoiding tanning beds. [2]
References
- NHS (UK). Sunscreen and sun safety. Read 2026-10-22.
- National Cancer Institute (US). Cancer Risk Factors: Sunlight. Read 2026-10-22.
- MedlinePlus, U.S. National Library of Medicine. Vitamin D (encyclopedia article, reviewed 1/21/2025). Read 2026-10-22.
- Sun-D Trial, 2025. Effect of daily sunscreen application on vitamin D: findings from the open-label randomized controlled Sun-D Trial. Br J Dermatol. PMID 40927943. Read 2026-10-22.
- Holick et al. 1985. Aging decreases the capacity of human skin to produce vitamin D3. J Clin Invest. PMID 2997282. Read 2026-10-22.
- MedlinePlus, U.S. National Library of Medicine. Vitamin D Test (medical test page). Read 2026-10-22.
- NHS (UK). Vitamins and minerals: Vitamin D. Page last reviewed 3 August 2020. Read 2026-10-22.
- Webb et al. 2020. Ultraviolet Exposure Scenarios: Balancing Risks of Erythema and Benefits of Cutaneous Vitamin D Synthesis. Adv Exp Med Biol. PMID 32918230. Read 2026-10-22.
- Skin pigmentation and vitamin D-folate interactions review, 2021. Skin pigmentation and vitamin D-folate interactions in vascular function: an update. Curr Opin Clin Nutr Metab Care. PMID 34456246. Read 2026-10-22.
- Neale et al. 2019. The effect of sunscreen on vitamin D: a review. Br J Dermatol. PMID 30945275. Read 2026-10-22.
- Demay et al. 2024. Vitamin D for the Prevention of Disease: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. PMID 38828931. Read 2026-10-22.