What is vitamin D and what does it do?

Vitamin D, one of the fat-soluble vitamins, has been identified as a vital component to develop and maintain strong and healthy bones throughout life. In addition, there is growing evidence that it may play an important role in the prevention of a number of serious diseases, including cardiovascular disease, diabetes, some inflammatory conditions and some cancers. Your body needs vitamin D for other functions too. Your muscles need it to move, and your nerves need it to carry messages between your brain and your body. Your immune system needs vitamin D to fight off invading bacteria and viruses.

Vitamin D is needed at all stages throughout life, however it can be difficult to achieve the recommended intake everyday. Often known as the ‘sunshine vitamin’, it is largely produced in the body through exposure of the skin to sunlight. However, due to Ireland’s latitude, 51-55 degrees north, from November to March there is inadequate quality and quantity of sunlight to enable sufficient production of vitamin D by the body to reach the recommended dietary allowances (RDA).

How much do we need and are we getting enough?

The recommended daily intake of vitamin D in adults is 10mcg per day and 15 mcg for older adults (over 65 years of age)

The FSAI recommend that our diets should include regular intakes of natural sources of vitamin D, such as oily fish, eggs, meats, and vitamin D-fortified foods

In 2011 over 90% of adults in Ireland had intakes of vitamin D below 10mcg per day (National Adult Nutrition Survey).

What foods provide vitamin D?

Very few foods naturally contain vitamin D. Fatty fish (like salmon, tuna, mackerel and trout) are among the very best natural sources of vitamin D.

Beef liver, egg yolks, and cheese have small amounts of vitamin D. Vitamin D is added to many breakfast cereals and to some brands of orange juice, yogurt, margarine, and other food products.

Can I get vitamin D from the sun?

Your body makes vitamin D when your bare skin is exposed to the sun. Most people get at least some vitamin D this way. However, clouds, smog, old age, and having dark-coloured skin reduce the amount of vitamin D your skin makes. Also, your skin does not make vitamin D from sunlight through a window. Ultraviolet radiation from sunshine can cause skin cancer, so it’s important to limit how much time you spend in the sun. Although sunscreen limits vitamin D production, health experts recommend using sunscreen with a sun protection factor (SPF) of 15 or more when you’re out in the sun for more than a few minutes.

John West Ireland

Witten by Aileen Regan

Consultant Nutritionist