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Vitamin D is a fat soluble vitamin that is present in only a few foods in our diet. It is needed for healthy bones and teeth and to help control how calcium and phosphorus are used in the body.
Recently a role for vitamin D has been identified in keeping muscles healthy and strong, in the immune system and in helping to reduce falls amongst the elderly. Other roles for vitamin D have been suggested such as heart and circulatory health and cancer prevention but as yet there is not enough evidence to confirm them.
In the UK most of our vitamin D comes from exposing our skin to sunlight. But there is a problem. In the UK there is only enough of the right kind of UV sunlight at certain times of the year. In October and November and throughout the winter there is just not enough to make enough vitamin D in the skin.
Who is at risk?
About 2 in every 5 people have low levels of vitamin D during the winter months when our vitamin D stores have all been used up. Some people are at higher risk of vitamin D deficiency all year round:
• Infants, children and older people
• Anyone who is housebound or covers up outdoors
• Anyone with pigmented skin
• Pregnant and breastfeeding women
We only need very small amounts of vitamin D and our needs are expressed in micrograms. A microgram is one millionth of a gram. Micrograms are usually shortened to mcg or μg. We use mcg on this page. The UK daily recommended intake of vitamin D from foods has recently (2016) been set at 10mcg per day for all ages*. This is the average amount of vitamin D needed each day to maintain healthy levels of vitamin D in the blood during the winter or when exposure to sunlight is minimal.
How to achieve the recommend intake of vitamin D
There are few good sources of vitamin D in the diet.
• Infant formula
• Oily fish – such as herring, mackerel, salmon and sardines
• Liver and fish liver oil
• Some breakfast cereals
• Some dairy products, such as full fat milk and yoghurts
• Fortified spreads
Average vitamin D intakes are around 2-3 mcg per day. Most people find it difficult to get the recommended intake of vitamin D from foods alone.
Is a lack of vitamin D harmful?
Deficiency of vitamin D has become more common in the UK in the last decade. This might be because we spend less time spent outdoors and we routinely use creams that block UV sunlight. Lacking vitamin D can lead to bone problems such as rickets in children and osteomalacia in adults.
In 2016 the government announced new public health measures to improve the vitamin D status of the UK population. These include:
• Those people at high risk who are unlikely to get enough vitamin D form their diet should consider taking a vitamin D supplement throughout the year
• Those people who are unlikely to get sufficient vitamin D from their diet should consider taking a vitamin D supplement from October to March
Taking a vitamin D supplement
To get all the vitamin D you need you will need to source a vitamin D supplement that contains 10mcg of vitamin D per day. If you buy one that contains more than this then just take it less often so that your average intake is 10mcg per day. You might find that some supplements are declared as i.u. or international units. 10 mcgs of vitamin D is the equivalent of 400 i.u. (1 mcg 40 i.u.).
There are two forms of vitamin D in food supplements and fortified foods. Vitamin D3 and vitamin D2. Vitamin D2 is often used by food makers as a vegetarian source of the vitamin. Vitamin D3 comes from lanolin, a bi-product of sheep’s wool. In studies vitamin D3 has been shown to be considerably more effective at raising the level of vitamin D in the blood than vitamin D2.