Vitamin D

Vitamin D is essential for good health, but most of us don’t get enough. It’s possible to get more from supplements and sunlight.

Why we need vitamin D

Vitamin D helps you absorb calcium and phosphorus from your diet and use these minerals to keep your bones, teeth and muscles strong. This helps prevent falls as you get older.

Vitamin D may have other roles in the body’s immune system and heart health too.
A lack of vitamin D can cause bone problems such as rickets (which causes bowed legs) in children and muscle weakness and painful or tender bones in adults.

How we make vitamin D

We get a little vitamin D from food, but we get most of it from sunlight. The sun acts on chemicals under the skin and helps turn them into vitamin D. In winter in the UK, we don’t get enough of the right type of sunlight to make enough vitamin D.

Not getting enough vitamin D

We don’t need vitamin D from food or sunlight every day. But if you don’t get enough over a longer period of time, you won’t have enough vitamin D for good health – known as vitamin D deficiency. This is very common in the UK – around one in five adults and one in six children don’t have enough vitamin D.

Some people are more likely to have a vitamin D deficiency than others. Supplements and eating foods which contain vitamin D can help.

Vitamin D and cholesterol

Vitamin D is linked to cholesterol because we need cholesterol in our skins cells to make vitamin D from sunlight. The vitamin D is later transformed again in the liver and kidneys, but cholesterol is needed for the first step.

Vitamin D and statins

There has been some debate around whether statins could stop us making enough vitamin D – because statins lower cholesterol. In reality, we have more than enough cholesterol to make vitamin D, even if you take statins. It’s more important to make sure you’re getting enough time in sunlight or getting enough vitamin D from foods or supplements.

Muscle problems that are thought to be caused by statins

It’s possible that muscle aches and pains that are often thought to be caused by statins are actually caused by a lack of vitamin D. Too little vitamin D can cause muscle weakness and tenderness in the bones – these muscle problems seem very similar to the ones linked to statins.

Because a lack of vitamin D is so common, it’s likely that many people who are taking statins don’t have enough vitamin D.

Your doctor can check if you have enough vitamin D in your blood using a simple blood test.

How much vitamin D is enough?

Adults and children over the age of one need 10mcg (micrograms) of vitamin D per day. This is the same for everyone, including people at risk of vitamin D deficiency and women who are pregnant or breastfeeding.

Babies up to one year old need 8.5-10mcg of vitamin D per day. Find out more about how you can reach this from the NHS.

How to get enough vitamin D

Getting vitamin D from sunlight

To make vitamin D, you need sunlight on your skin. From April until the end of September it’s possible to get enough vitamin D by spending time outside.

For most people, you only need to be outside for short periods of time, for example around 20-30 minutes. Although the exact time isn’t known because it’s different for different people. If you have dark skin, for example if you’re of south Asian, African or African Caribbean origin, you will need longer in the sun.

You need to have some skin exposed, for example, your forearms, hands and lower legs. But you can still make vitamin D even if you sit in the shade.

Sitting inside by a sunny window doesn’t count because glass filters out the UVB rays – the type of light that is needed to make vitamin D.

In the UK, we don’t get enough vitamin D from sunlight between October and March, because the light doesn’t contain enough UVB rays. During this time, we need to rely on getting enough vitamin D from food, and possibly supplements.

The guidelines in the UK are that everyone should consider taking a vitamin D supplement in the winter, especially if you’re more like to have a deficiency.

Protecting your skin

Suntan lotions protect your skin from the sun but they also prevent your skin from making vitamin D.

If you are going to sit in strong sunlight for some time, or if your skin is sensitive, then you will need to protect your skin so it doesn’t burn. Wear sunscreen and a hat in summer if you’re out for a long time and avoid mid-day sun on hot summer days. Find out more about your skin type and avoiding sunburn from Cancer Research UK.

Getting vitamin D from food

Most foods don’t contain much vitamin D so it’s hard to get enough vitamin D from food alone.

Foods which contain vitamin D include:

  • oily fish – such as salmon, sardines, mackerel, trout and fresh tuna
  • red meat
  • liver and fish liver oil
  • egg (yolks)
  • some dairy foods, including full fat milk and yoghurts – but you should avoid these if you have raised cholesterol because they are high in saturated fat
  • foods with vitamin D added – such as most fat spreads and some breakfast cereals
  • infant formula – which has vitamin D added to make sure babies get enough.

As most of these foods are animal products, it’s harder to get vitamin D from food if you are vegan or vegetarian.

People most at risk of vitamin D deficiency

Some people don’t have enough vitamin D. This could be because their skin isn’t exposed to enough sunlight, or because of health problems or higher needs for vitamin D.

For example, if:

  • you don’t go outdoors often, for example if you are housebound, in hospital or are disabled and less able to get about
  • you wear clothes which cover most of your skin when you go outside
  • you have dark skin, for example if you’re from an African, African-Caribbean or south Asian background – as you need more sunlight to make enough vitamin D
  • you wear sunscreen most or all of the time
  • you need more vitamin D, babies, young children and pregnant and breastfeeding women need more vitamin D
  • you are an older adult, as older people can’t make as much vitamin D
  • you have a health problem or you’re taking certain medications which change the way vitamin D is controlled in the body, such as Crohn’s disease, coeliac disease, and some types of liver and kidney disease.
  • you are very overweight, a there is some evidence to suggest that people who are very over weight are more likely to lack vitamin D
  • you eat very few foods that contain vitamin D.

Taking supplements

Any one at risk of not getting enough vitamin D should take a vitamin D supplement – especially during the winter months but ideally all year round.

Adults and older children will need a daily supplement which contains 10mcg of vitamin D. This will sometimes be written as 400IU (international units).

There are special vitamin drops available for babies and children under 5. These may be available free of charge for some families. If you are pregnant and breastfeeding you may also be able to claim free vitamin D tablets.

If you are not in one of the groups above and you simply want to make sure you’re taking enough, you can consider taking a vitamin D supplement during the winter, when the levels of vitamin D in our blood usually drops.

You can’t get too much vitamin D from sunlight, but it is possible to take too much vitamin D if you take a supplement that has a high dose, and you take it for a long time. This can cause a build-up of calcium in the body, which can damage your bones, heart and kidneys.

So, if you are taking supplements, then 10mcg each day should be enough. More is not necessarily better. Don’t go over 25mcg a day for adults unless your doctor advises you to. If in doubt, check the advice about the dose on the pack or speak to your doctor about what’s right for you.

Find out more about vitamin D and how to get enough, including the guidelines for pregnant women and babies, from the NHS.