Everyone needs vitamin D to help the body absorb calcium and phosphorus from their 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. We also get 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?
The amount of time you need to spend in the sun for your skin to make enough vitamin D is different for every person. This is because the amount of time needed depends on a number of factors, such as your skin type (how dark your skin is or how easily you get sunburnt), the time of year and what time of day it is.
Short daily periods of sun exposure without sunscreen during the summer months (April to October) are enough for most people to make enough vitamin D. Evidence suggests the most effective time of day for vitamin D production is between 11am and 3pm.
A short period of time in the sun means just a few minutes – evidence suggests 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. People with darker skin will need to spend longer in the sun to produce the same amount of vitamin D.
The larger the area of skin exposed to sunlight, the more chance there is of making enough vitamin D before you start to burn.
In the UK, our skin isn't able to make vitamin D from winter sunlight (November to March) as the sunlight hasn't got enough ultraviolet B (UVB) radiation. During the winter, we get vitamin D from our body's stores and food sources.
The longer you stay in the sun, especially for prolonged periods without sun protection, the greater your risk of skin cancer.
Remember to cover up or protect your skin before the time it takes you to start turning red or burn. Stay covered up for most of the time you spend outside and use sunscreen with a sun protection factor (SPF) of at least 15.
Sunbeds are not a recommended source of vitamin D.
Read more about keeping skin safe in the sun.
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
It's important that pregnant and breastfeeding women 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 more 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.
Further information on vitamin D
The Department of Health's recommendations on taking vitamin D supplements are based on advice from the Scientific Advisory Committee on Nutrition (SACN).
The SACN produced a report in 2007 that summarised the scientific evidence on vitamin D and health. It is now reviewing the latest evidence on vitamin D and health, and will report on this when it is complete.
In 2010, seven British health organisations produced a joint statement of their views on vitamin D. Read the joint statement on vitamin D.
Find out how sunburn damages your skin on the Cancer Research UK website.
Find out more about healthy diet in pregnancy.