Vitamin D

Vitamin D has several important functions. For example, it helps regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones and teeth healthy. A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain and tenderness as a result of a condition called osteomalacia in adults.

Good sources of vitamin D

We get most of our vitamin D from sunlight on our skin. The vitamin is made by our body under the skin in reaction to summer sunlight. However, if you are out in the sun, take care to cover up or protect your skin with sunscreen before you turn red or get burnt. Vitamin D is also found in a small number of foods. Good food sources are:

• oily fish, such as salmon, sardines and mackerel
• eggs
• fortified fat spreads
• fortified breakfast cereals
• powdered milk

How much vitamin D do I need?

Most people should be able to get all the vitamin D they need by eating a healthy balanced diet and by getting some summer sun. Groups of the population at risk of not getting enough vitamin D are:

• all pregnant and breastfeeding women
• babies and young children under the age of five
• older people aged 65 years and over
• people who are not exposed to much sun, such as people who cover up their skin when outdoors, or those who are housebound or confined indoors for long periods
• people who have darker skin such as people of African, African-Caribbean and South Asian origin

It is recommended that:

• all pregnant and breastfeeding women should take a daily supplement containing 10 micrograms (0.01mg) of vitamin D to ensure the mother's requirements for vitamin D are met and to build adequate foetal stores for early infancy
• all babies and young children aged six months to five years should take a daily supplement containing vitamin D in the form of vitamin drops to help them meet the requirement set for this age group of 7-8.5 micrograms (0.007-0.0085mg) of vitamin D a day
• babies fed infant formula will not need vitamin drops until they are receiving less than 500ml (about a pint) of infant formula a day, as these products are fortified with vitamin D
• breastfed infants may need to receive drops containing vitamin D from one month of age if their mother has not taken vitamin D supplements throughout pregnancy
• people aged 65 years and over and people not exposed to much sun should also take a daily supplement containing 10 micrograms (0.01mg) of vitamin D

You can buy single vitamin D supplements or vitamin drops containing vitamin D (for use by under-fives) at most pharmacies and supermarkets.

What happens if I take too much vitamin D?

If you take vitamin D supplements, do not take more than 25 micrograms (0.025mg) a day, as it could be harmful. However, taking less than this is unlikely to cause any harm. Your body doesn't make too much vitamin D from sun exposure, but always remember to cover up or protect your skin if you are out in the sun for long periods. Taking too many vitamin D supplements over a long period of time can cause more calcium to be absorbed than can be excreted. The excess calcium can be deposited in and damage the kidneys. Excessive intake of vitamin D can also encourage calcium to be removed from bones, which can soften and weaken them.