A dose of sunshine

Julie Dowsett continues our series on food supplements with a look at vitamin D - the sunshine vitamin.

Vitamin D is one of the fat soluble vitamins. It is not excreted by the body, and so it's important to avoid taking too much of it. But don't panic - it's virtually impossible to overdose on vitamins through the food we eat. However, it is possible to take in too much in the form of vitamin supplements. That's why anyone considering taking a vitamin supplement should be aware of how much it contains and should not exceed the recommended dose.

Many people feel that if a little bit does you good, a larger amount must do you better. This is not the case with vitamins!

Vitamin D is the vitamin often referred to as the 'sunshine vitamin'. This is because we get it not only from food, but also from the action of sun rays on our skin. Most of the population can get enough of the vitamin in this way. It takes only 15 minutes of exposure to sunlight on a patch of skin the size of the back of your hand to produce the required amount of vitamin D in the day.

What does vitamin D do?

The main role of vitamin D is in the area of bone health. Vitamin D helps with the absorption of calcium. Low levels of vitamin D are associated with bone disorders such as osteoporosis and osteomalacia. Vitamin D deficiency in childhood is associated with rickets, a bone disorder that is thankfully nearly unheard of in now Ireland.

Dietary sources of vitamin D include oily fish such as herring, mackerel, pilchards and tuna. Other sources are eggs, fortified foods such as some margarine, milks and breakfast cereals.

UK guidelines suggest that people older than 65 should consume 101 ug of vitamin D daily. There is no recommended amount for the rest of the population because most people get enough vitamin D from sunlight.

However, some people don't get enough exposure to the sun, and this is the group of people who must make sure to take adequate vitamin D in their diets. Here are a few recommendations for these people:

Elderly people

As this is the year of the older person, I am going to put this group at the top of the list. Many house-bound or hospitalised older people are at risk of vitamin D deficiency. For many of these people, a supplement of vitamin D, such as cod liver or halibut liver oil, may be necessary.

Asians

As many Asian women cover themselves from the sun, there is a higher than average incidence of rickets (the deficiency disease of vitamin D) in the children of vitamin D deficient mothers.

Pregnancy and lactation