Vitamin D in the UK Winter: Who Should Supplement?

In the UK, most of our vitamin D comes from sunlight on our skin. From October to early March, the sun is too low in the sky for this to work well. That is why the NHS advises everyone to consider a vitamin D supplement during the autumn and winter.

Why vitamin D matters

Vitamin D contributes to:

• the normal function of the immune system
• the maintenance of normal bones and teeth
• the maintenance of normal muscle function
• normal absorption and use of calcium and phosphorus

Why UK sunlight isn't enough in winter

Your skin makes vitamin D when it is exposed to UVB light. In the UK, UVB is too weak from roughly October to March, so your skin makes very little vitamin D in those months, however much time you spend outside. Shorter days, more time indoors and more layers of clothing add to the problem.

What the NHS recommends

• Everyone aged 1 and over: consider taking 10 micrograms (400 IU) of vitamin D a day during autumn and winter.
• All year round: people who are rarely outdoors, live in a care home, usually cover most of their skin outdoors, or have dark skin (for example people of African, African-Caribbean or South Asian origin) should consider 10 micrograms a day throughout the year.
• Upper limit: adults should not take more than 100 micrograms (4,000 IU) a day unless a doctor advises it.

Food sources of vitamin D

Food alone rarely provides enough, but these help:

• oily fish: salmon, sardines, mackerel, herring
• egg yolks
• red meat and liver
• fortified foods, such as some breakfast cereals, plant milks and spreads

Vitamin D3 vs D3 + K2

D3 (cholecalciferol) is the form your skin makes, and it is the form most supplements use. Some products combine it with vitamin K2, which contributes to the maintenance of normal bones and to normal blood clotting.

People choose D3 + K2 when they want both nutrients in one daily dose. If you take blood-thinning medication such as warfarin, speak to your doctor before taking anything with vitamin K.

Vitastrong offers Vitamin D3 and Vitamin D3 + K2. For a wider winter routine, pair it with Vitamin C + Zinc and a daily Multivitamin.

How to take vitamin D

• With food: vitamin D is fat-soluble, so taking it with a meal that contains some fat can help absorption.
• Consistently: a daily habit is easier than remembering a weekly dose.
• Count every source: if your multivitamin already contains vitamin D, add up the total so you stay within the upper limit.

A simple winter routine

1. Take a daily vitamin D supplement from October to March.
2. Get outside in daylight every day. It is good for your mood and sleep rhythm even if your skin isn't making much vitamin D.
3. Eat oily fish once or twice a week.
4. Keep training. Regular movement supports overall wellbeing through the darker months.
5. Prioritise sleep and eat plenty of fruit and vegetables for vitamin C.

Products mentioned in this article

FAQs

Is 400 IU enough?

It is the NHS recommended amount for the general population. Your doctor may advise a higher dose if a blood test shows you are deficient.

Can I get a vitamin D test?

Your GP can test your levels if there is a clinical reason. Home finger-prick tests are also available privately.

Should children take vitamin D?

Yes. The NHS has separate advice for babies and children, so use a product made for their age.

This article is for information only and does not replace medical advice. Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle.