Vitamin D is important for healthy bones and teeth. It helps the body to absorb and regulate the minerals calcium and phosphate from the food you eat.
Most of the vitamin D we get comes from safe exposure to the summer sun, but some foods also contain vitamin D.
Vitamin D food sources
Good food sources of vitamin D include:
- Oily fish, including salmon and sardines
- Fortified spreads
- Fortified breakfast cereal
- Powdered milk
Vitamin D uses
Vitamin D is important for people with osteoporosis. Studies show that calcium and vitamin D together can increase bone density in postmenopausal women. Vitamin D deficiency may cause disorders associated with weak bones, such as rickets in children or osteomalacia in adults, and may lead to hormone problems, muscle weakness and pain, and other symptoms.
Studies have found prescription-strength vitamin D lotions helpful in treating psoriasis. Vitamin D has also been studied for other conditions ranging from cancer prevention to high blood pressure, but the evidence is unclear.
Some people get enough vitamin D from their diet and from some exposure to sun in the summer months. However, in the summer of 2016 health officials from Public Health England and the Welsh Government began recommending people get 10 micrograms of vitamin D a day though their diet or supplements.
The UK's Scientific Advisory Committee on Nutrition (SACN) made the recommendation after reviewing all the evidence on vitamin D and health. It couldn’t determine how much vitamin D we get though skin being exposed to the sun - so instead focuses on diet.
It is hard to get the daily amount of vitamin D needed from food, so most adults and children aged 4 and over are asked to consider supplements containing 10 micrograms of vitamin D every day during autumn and winter.
Supplements are recommended all year round for people with dark skin, including people from African, African-Caribbean and South Asian backgrounds.
Children aged 1-4 years should have a 10 microgram vitamin D supplement every day all year round.
All babies under a year old should have a daily 8.5 to 10 microgram vitamin D supplement, even if they are breastfed exclusively up to around 6 months under official advice.
The guidelines are different for formula-fed children who have more than 500ml of infant formula a day. They don't need extra vitamin D because formula is already fortified with it.
Supplements of vitamin D come in various forms, including tablets, and for children, special drops. Women who are pregnant or breastfeeding and children under 4 may qualify for free supplements containing vitamin D under the Healthy Start programme.
Can you have too much vitamin D?
While too little vitamin D can cause health problems, too much is also harmful. Taking too much vitamin D over a long period can cause more calcium to be absorbed than the body can cope with. That can cause kidney problems and actually soften and weaken bones rather than maintain bone health.
The NHS says if a person decides to take vitamin D supplements, 100 micrograms or less a day is unlikely to cause any harm.
You cannot get too much vitamin D from being in the sun, but it is important to get the balance right with sun exposure. Your body needs enough sun in the summer months to make vitamin D, but not so much that the skin burns as that increases the risk of skin cancer.