Vitamin D and Darker Skin: Why Winter Matters More Than You Think
The clocks have gone back and the days are getting shorter. If you have brown or black skin and live in the UK, here is why the NHS suggests a vitamin D supplement all year, and how to get it right without overdoing it.
TL;DR: In the UK, the NHS advises everyone to consider a daily 10 microgram (400 IU) vitamin D supplement from October to March, because winter sunlight is too weak for your skin to make enough. If you have dark skin, for example an African or African-Caribbean background, the advice is to consider taking it all year round. Melanin means your skin makes vitamin D more slowly, and low levels can affect your bones, muscles and pregnancy. Stick to the recommended dose unless a doctor tells you otherwise, because too much can be harmful.
The clocks went back this morning. If you live in the UK, you will feel it by Wednesday: darker at five o'clock, grey commutes, a whole season of leaving and coming home without much daylight. For most people that is just a mood. For your body, it is also a supply problem, because the sunshine your skin uses to make vitamin D has quietly gone weak until spring.
If you have brown or black skin, that problem starts earlier and runs deeper. This is not about blame or about your skin being a flaw. It is physics, geography and a few simple habits that can close the gap.
What vitamin D does for you
Vitamin D helps your body control calcium and phosphate, the minerals that keep your bones, teeth and muscles healthy. When levels drop low for long enough, adults can develop osteomalacia, a softening of the bones. The NHS lists signs such as pain in your back, ribs, pelvis or legs, muscle weakness that makes stairs harder, tiredness, and muscle cramps or twitching. In children, long-term deficiency causes rickets.
The tricky part is that mild deficiency often has no obvious symptoms at all. You can feel mostly fine while your stores run down, which is why the UK advice is built around prevention rather than waiting for signs. Over decades, strong bones also protect you later in life, something we explore in our guide to bone health and osteoporosis.
Why does darker skin make less vitamin D?
Melanin, the pigment that gives your skin its colour, absorbs the ultraviolet B (UVB) light your skin needs to start making vitamin D. More melanin means less UVB reaches the layer where vitamin D is made, so darker skin generally needs more sun exposure to produce the same amount. Scientists still debate exactly how much more, but the direction is consistent.
That built-in sun protection is a gift in Lagos or Accra, where UVB is strong all year. In Manchester or Glasgow in November, it becomes a disadvantage. A review of how skin makes vitamin D describes how melanin competes for the same UVB light, which is why skin tone, latitude and season all stack together.
What does the NHS recommend?
The NHS says that between October and early March, nobody in the UK makes enough vitamin D from sunlight, so everyone, including pregnant and breastfeeding women, should consider a daily 10 microgram supplement in autumn and winter. For people with dark skin, such as those from African, African-Caribbean or south Asian backgrounds, and for anyone who is not often outdoors, the advice is to consider taking it every day of the year.
That 10 microgram figure comes from the Scientific Advisory Committee on Nutrition (SACN), whose 2016 report set it as the amount most people need when sun exposure is minimal. You may see it written as 10 mcg, 10 µg or 400 IU on a label. They all mean the same dose.
A few practical notes:
- It is cheap and easy to find. Basic vitamin D3 tablets are sold in most UK pharmacies and supermarkets.
- Healthy Start can help. If you are pregnant or have young children and qualify for the Healthy Start scheme, you can get free vitamins that include vitamin D.
Can you get enough vitamin D from food?
Food helps, but it is hard to reach 10 micrograms a day from diet alone, which is exactly why the NHS leans on supplements. Still, it is worth knowing which foods carry vitamin D, and plenty of them are already in West African kitchens.
The NHS lists oily fish, red meat, liver, egg yolks and fortified foods as sources. In everyday terms, that looks like:
- Mackerel and sardines. Tinned mackerel (the classic Titus tin) in a pepper stew or tomato sauce, sardines on bread or in jollof, or grilled fresh mackerel.
- Eggs. The vitamin D sits in the yolk, so the boiled egg in your stew or your morning omelette counts.
- Liver and red meat. Beef or chicken liver in pepper soup or fried with onions. If you are pregnant, the NHS advises avoiding liver because of its high vitamin A content.
- Fortified foods. Some breakfast cereals, spreads and plant milks have vitamin D added. Check the label rather than assuming.
Think of food as a top-up rather than the whole answer. A tin of mackerel twice a week is a good habit, and the supplement covers the rest.
Vitamin D, bones and pregnancy
During pregnancy, vitamin D helps your baby's bones and teeth develop. The NHS advises 10 micrograms a day between early October and late March for all pregnant women, and all year round if you have black or brown skin, cover most of your skin outdoors, or spend a lot of time indoors. Many pregnancy multivitamins already include it, so check your label before adding a second product.
If you are planning a pregnancy or are already pregnant, our pregnancy nutrition guide walks through vitamin D alongside folic acid, iron and other nutrients. And because Black women in the UK face higher risks in pregnancy overall, our piece on Black maternal health is worth reading too.
Living in Africa does not mean you are covered
It is easy to assume that anyone living near the equator gets plenty of vitamin D. The evidence says otherwise. A systematic review of vitamin D status across Africa, published in The Lancet Global Health, found that low vitamin D was common, with levels lower in women than men, in urban areas than rural ones, and in newborns than their mothers. The authors called for public health efforts focused on women, newborn babies and urban populations.
Why would that be in sunny countries? The NHS notes that covering most of your skin outdoors and spending a lot of time indoors both reduce how much vitamin D your skin makes. In Lagos, Nairobi or Johannesburg, plenty of women cover up for faith, culture or comfort, commute in the dark, and work long hours in offices, banks, hospitals and shops. Sunshine outside the window does not count if it never reaches your skin. If you live in Africa and have symptoms like bone pain or muscle weakness, low vitamin D is worth raising with your doctor.
Should you get your vitamin D level tested?
Most people following the NHS advice do not need a test. A blood test for 25-hydroxyvitamin D can confirm a deficiency if you have symptoms like bone pain or muscle weakness, a condition that affects absorption, or you are not sure whether you are getting enough. SACN uses a blood level below 25 nmol/L as the point where the risk to bone and muscle health goes up. Your GP or doctor can tell you whether a test makes sense and, if your level is very low, may prescribe a higher treatment dose for a set period.
Can you take too much vitamin D?
Yes. The NHS warns that taking too many vitamin D supplements over a long period can cause too much calcium to build up in the body (hypercalcaemia), which can weaken the bones and damage the kidneys and the heart. Adults should not take more than 100 micrograms (4,000 IU) a day unless a doctor advises it. Children aged 1 to 10 should not have more than 50 micrograms a day, and babies under 12 months no more than 25 micrograms.
High-strength tablets are easy to stack by accident with a multivitamin or pregnancy supplement, so add up the vitamin D across every label. For most adults, 10 micrograms a day is enough. Sunlight itself does not cause vitamin D toxicity, but it can still burn, even on darker skin.
Small steps for the darker months
- Pick one vitamin D supplement at 10 micrograms and take it with breakfast so it becomes routine.
- Get outside in daylight when you can, especially at lunchtime, even on cloudy days.
- Add mackerel, sardines and eggs to your weekly meals.
- If you have bone pain, muscle weakness or ongoing tiredness, see your GP rather than guessing. Tiredness has many causes, including iron deficiency and thyroid problems.
Asele can help you keep track. Logging symptoms like tiredness, aches and low mood alongside your cycle gives you a clearer picture over the winter, and the Asele Health Brief turns those notes into a short summary you can bring to your GP appointment. If you want to talk through what you are eating or how you are feeling, Amara can chat with you in Yoruba, Hausa, Igbo, Swahili, French or English. You can find us at Asele.
This post is education, not medical advice. If you are pregnant, have a health condition or take other medicines, check with your doctor or pharmacist before starting any supplement.
References
- NHS. Vitamin D. nhs.uk
- NHS. Pregnancy vitamins and supplements. nhs.uk
- NHS. Rickets and osteomalacia. nhs.uk
- Scientific Advisory Committee on Nutrition. Vitamin D and health report, 2016. gov.uk
- NHS Healthy Start. Getting vitamins. healthystart.nhs.uk
- Mogire RM, et al. "Prevalence of vitamin D deficiency in Africa: a systematic review and meta-analysis." The Lancet Global Health, 2020. pubmed.ncbi.nlm.nih.gov
- Uçar N, et al. "Illuminating the Connection: Cutaneous Vitamin D3 Synthesis and Its Role in Skin Cancer Prevention." Nutrients, 2025. pmc.ncbi.nlm.nih.gov
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