Do I Need Vitamin D in Winter? A Simple UK Guide

Here's something most people in the UK don't realise: from around October to early March, the sun simply isn't strong enough for your skin to make vitamin D. It doesn't matter how long you spend outside. The UVB rays you need just aren't there.

So every winter, a lot of us quietly run low. The latest national survey found that 31% of adults aged 19 to 64 were deficient in the winter months, and for 11 to 18 year olds it was 36%.

The good news is that it's one of the easiest things to fix.

The short answer Yes, most people in the UK should consider a vitamin D supplement in winter. The NHS advises everyone, including pregnant and breastfeeding women, to consider a daily 10 microgram (400 IU) supplement in autumn and winter. Some people should take one all year round (see the list below).

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Why it matters

Vitamin D helps your body absorb calcium and phosphate, which keep your bones, teeth and muscles healthy. It also plays a part in how your immune system works.

When levels drop too low for too long, you might notice:

• tiredness that doesn't lift
• aching bones or muscles
• low mood
• picking up every bug that's going around

These signs are very common and can have lots of other causes, so they're not proof on their own. If you're worried, speak to your GP.

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Should you take it all year round?

The NHS says some people should consider a daily supplement all year, not just in winter. Tick any that apply to you or someone you care for:

• ☐ You're not often outdoors, for example if you're unwell, housebound or work long indoor hours
• ☐ You live in a care home or similar setting
• ☐ You usually cover most of your skin when you're outside
• ☐ You have dark skin, for example if you have an African, African-Caribbean or South Asian background
• ☐ You're caring for a baby or a child aged 1 to 4 (see below)

If you ticked any, a year-round supplement is worth talking about with your GP or pharmacist.

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How much is right?

| Who | What the NHS advises | |---|---| | Adults and children over 4 | Consider 10 micrograms (400 IU) a day in autumn and winter | | Children aged 1 to 4 | 10 micrograms a day, all year | | Babies from birth to 1 year | 8.5 to 10 micrograms a day, all year, if breastfed or having less than 500ml of formula a day |

Don't take too much. The NHS says adults should not take more than 100 micrograms (4,000 IU) a day, children aged 1 to 10 no more than 50 micrograms (2,000 IU), and babies under 12 months no more than 25 micrograms (1,000 IU). Too much over a long time can be harmful. If your GP has prescribed a higher dose, follow their advice.

Tip: check the label. Some products show micrograms (µg), some show IU. 10 micrograms = 400 IU.

Money tip: if you're pregnant or have young children and get certain benefits, you may be able to get free vitamins through the Healthy Start scheme.

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Can you get enough from food?

Food helps, but it's very hard to get enough from food alone. Good sources include:

• Oily fish: salmon, sardines, trout, herring and mackerel (tinned counts!)
• Eggs: the vitamin D is in the yolk
• Red meat
• Fortified foods: some breakfast cereals and fat spreads (check the label)
• Liver (but not if you're pregnant)

One thing that surprises people: cow's milk in the UK isn't fortified, so it's not a good source of vitamin D.

Easy winter ideas:

• Sardines on wholegrain toast for lunch
• A boiled egg with breakfast
• Salmon or mackerel with vegetables once or twice a week
• A fortified cereal on busy mornings

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Your gut and vitamin D

There's growing interest in how vitamin D and the gut affect each other. Research suggests vitamin D plays a role in keeping the gut lining healthy and may influence the mix of bacteria living there. Studies have also found low vitamin D is common in people with some gut conditions, such as IBS, possibly because an unsettled gut absorbs nutrients less well.

The science is still developing, but it's one more reason to keep your levels topped up. Low vitamin D has also been linked to poorer sleep, as we explain in Can't Sleep? 10 Gut-Friendly Fixes for Insomnia.

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Guessing or knowing?

Everyone's level is different. It depends on your skin, your diet, your weight, how much time you spend outdoors and how well your gut absorbs nutrients. Two people can follow exactly the same advice and end up with very different levels.

If you'd rather know than guess, there are two routes:

1. Your GP can arrange a blood test if there's a medical reason, for example if you have symptoms or a condition that affects absorption.
2. A home finger-prick test gives you a clear reading of your level, so you can see whether what you're doing is working, and check again after a few months.

Power Gut helps you access a vitamin D test from an established laboratory partner, and supports you with the results. Find out about testing

Want the deeper science? Read The Sunlight You Carry Inside: Unlocking the Power of Vitamin D.

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Quick answers

When should I start taking vitamin D? The NHS advises considering a supplement from autumn, around October, through to the end of March.

Can I get vitamin D from a sunny winter day in the UK? Not really. Between October and early March, sunlight in the UK doesn't contain enough UVB for your skin to make vitamin D.

Is D3 or D2 better? Research suggests D3 is better at raising and keeping up your blood levels. Most UK supplements are D3.

Can I take too much vitamin D? Yes. Don't go over 100 micrograms (4,000 IU) a day as an adult unless your GP advises it.

Should my children take vitamin D? Children aged 1 to 4 should have 10 micrograms a day all year. Older children should consider it in autumn and winter.

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More help: NHS: Vitamin D · NHS: Vitamins for children · NHS: Pregnancy vitamins and supplements

This article is for education only and isn't medical advice. Speak to your GP or pharmacist before starting supplements, especially if you're pregnant, have a health condition or take other medicines.

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This article is for educational purposes only and does not constitute medical advice. Always consult your GP or a qualified healthcare professional for personal medical guidance.