We need vitamin D to help the body absorb calcium and phosphorus from our diet. These minerals are important for healthy bones and teeth.
A lack of vitamin D – known as vitamin D deficiency – can cause bones to become soft and weak, which can lead to bone deformities. In children, for example, a lack of vitamin D can lead to rickets. In adults, it can lead to osteomalacia, which causes bone pain and tenderness.
How do we get vitamin D?
Our body creates most of our vitamin D from direct sunlight on our skin. The best time to make vitamin D from sunlight is from March to October, especially from 11am to 3pm.
We also get some vitamin D from some foods, including oily fish such as salmon, mackerel and sardines, as well as meat and eggs.
Vitamin D is also added to all infant formula milk, as well as some breakfast cereals, soya products, dairy products, powdered milks and fat spreads.
The amounts added to these products can vary and may only be added in small amounts. Manufacturers must add vitamin D to infant formula milk.
How long should we spend in the sun?
Most people can make enough vitamin D from being out in the sun daily for short periods with their forearms, hands or lower legs uncovered and without sunscreen from March to October, especially from 11am to 3pm.
A short period of time in the sun means just a few minutes – about 10 to 15 minutes is enough for most lighter-skinned people – and is less than the time it takes you to start going red or burn. Exposing yourself for longer is unlikely to provide any additional benefits.
People with darker skin will need to spend longer in the sun to produce the same amount of vitamin D.
How long it takes for your skin to go red or burn varies from person to person. Cancer Research UK has a useful tool where you can find out your skin type, to see when you might be at risk of burning.
You can’t make vitamin D from sitting indoors by a sunny window because ultraviolet B (UVB) rays can’t get through, but you can still burn.
The longer you stay in the sun, especially for prolonged periods without sun protection, the greater your risk of skin cancer.
If you plan to be out in the sun for long, cover up with suitable clothing, seeking shade and applying at least SPF15 sunscreen.
In the UK, our skin isn't able to make vitamin D from October to March, as the sunlight hasn't got enough UVB radiation.
During the winter, we get vitamin D from our body's stores, which are built up during the summer, and food sources.
Sunbeds are not a recommended source of vitamin D.
Babies and children
Children aged under six months should be kept out of direct strong sunlight.
From March to October in the UK, children should:
- cover up with suitable clothing
- spend time in the shade (particularly from 11am to 3pm)
- wear at least SPF15 sunscreen
To ensure they get enough vitamin D, children aged under five are advised to take vitamin D supplements even if they do get out in the sun. Find out about vitamin D supplements for children.
Who is at risk of vitamin D deficiency?
Some groups of the population are at greater risk of vitamin D deficiency, and the Department of Health advises these people to take daily vitamin D supplements.
These groups are:
- all pregnant and breastfeeding women
- all babies and young children from six months to five years old – unless they are having 500ml or more a day of infant milk formula
- older people aged 65 and over
- people who are not exposed to much sun – for example, those who cover their skin, or are housebound or confined indoors for long periods
- people who have darker skin – for example, those of African, African Caribbean or South Asian origin need more time in the sun than someone with lighter skin to produce the same amount of vitamin D
Pregnant and breastfeeding women should take a vitamin D supplement to make sure their own needs for vitamin D are met, and their baby is born with enough stores of vitamin D for the first few months of its life.
You can get vitamin supplements containing vitamin D free of charge if you are pregnant or breastfeeding, or have a child under four years of age and qualify for the Healthy Start scheme.
You can also buy single vitamin supplements or vitamin drops containing vitamin D for babies and young children at most pharmacies and larger supermarkets.
Speak to your pharmacist, GP or health visitor if you are unsure whether you have vitamin D deficiency or don't know what supplements to take.
Find out about vitamin D supplements and how much to take.
Can you have too much vitamin D?
People who take supplements are advised not to take more than 25 micrograms (µg) of vitamin D a day, as intakes from supplements above this amount could be harmful, according to the UK Expert Group on Vitamins and Minerals.
The amount of vitamin D contained in supplements is sometimes expressed in international units (IU), where 40 IU is equal to 1µg of vitamin D.
There is no risk of your body making too much vitamin D from sun exposure, but always cover up or protect your skin before the time it takes you to start turning red or burn.