The vital nutrient nearly a third of us aren't getting enough of

In the UK, 18% of adults are deficient in vitamin D, external. Come winter, this rises to 31%.

Given the nutrient's vital role in keeping muscles, bones and teeth healthy, how can we make sure we get enough?

Studies show, external that very low levels of vitamin D can cause our bones to become soft and weak. This is called rickets in children, and osteomalacia in adults.

There's also research that says adequate vitamin D levels can help prevent inflammatory diseases like rheumatoid arthritis, external and reduce the risk of acute respiratory tract infections, external. The vitamin is also linked to a lower risk of some cancers, external.

The problem? Vitamin D is only found in a small number of foods. Our bodies make most of it themselves, using sunlight.

That's why deficiency rates increase in winter in the UK. It's pretty much impossible for our bodies to produce the recommended 10 micrograms (mcg) a day between October and March, because the sun isn't strong enough.

When Kay Niknam from Bristol started experiencing bone aches and muscle weakness, she didn't think to seek help initially.

"I had been struggling increasingly with joint pain for several weeks, possibly months, when I went to see the GP.

"I was no longer able to carry my two-month-old daughter in a sling. Some days I struggled to walk because of the pain."

It turned out Kay's vitamin D levels were very low, so her GP prescribed high-strength vitamin D capsules.

"I noticed improvements in the first week, and after a few weeks was able to do all my normal activities again."

Some foods naturally come with vitamin D, such as:

Other foods and drinks are fortified with vitamin D, meaning it gets added during the production process. These include:

But, unfortunately, it's very difficult to get enough vitamin D from food and drink alone.

This is why the NHS, external recommends everyone over the age of five considers taking a daily supplement during winter months (it advises children under five and people at risk of deficiency should take supplements year-round).

But some experts have concerns about regularly taking vitamin D supplements – especially if people take excessive amounts. The NHS advises that taking more than 100mcg of vitamin D a day could be harmful, external.

One worry is that because vitamin D is fat-soluble, it can build up in the body. This could lead to vitamin D toxicity, and in turn damage the heart, kidneys and bones.

So if you decide to supplement, be sure to check the dosage, as many vitamin D supplements contain more than you need.

Remember, it's difficult to know how much vitamin D you are getting from other sources in addition to a supplement.

Some people are more at risk of vitamin D deficiency than others. Risk factors include:

Supplements tend to contain either vitamin D3 or D2.

Bahee Van de Bor, dietitian and British Dietetic Association, external (BDA) media spokesperson, explains, "Research, external suggests that vitamin D3 is better absorbed, although both D2 and D3 are absorbed well by the body.

"Vitamin D3 (cholecalciferol) comes from animal sources such as oily fish. Our skin is also able to make D3. D2 (ergocalciferol) is the plant version of the vitamin. If you are following a plant-based diet, D2 is still a reliable form of vitamin D supplement."

What might matter more than the type of vitamin D supplement you take, is how you take it.

"It's absorbed best when taken alongside a meal consisting of fat," says Van de Bor. So it's best to take it when you're going to eat.

That said, it doesn't matter which meal it is, or the time of day. Just find a regular time that works for you.

All content within this article is provided for general information only, and should not be treated as a substitute for the medical advice of your doctor or any other health care professional. Always consult your GP if you're concerned about your health.

Originally published January 2020. Updated March 2026.

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