201202-nutrition-focus-vitaminVitamin D is called the sunshine vitamin because the body mainly generates it through exposure to sunlight. A lack of this essential vitamin that comes from ultraviolet (UV) rays of the sun could leave you at risk of a range of health problems and you should, therefore, aim to get enough of it. A deficiency of vitamin D has been linked to an increased risk of multiple sclerosis, memory loss, diabetes, thinning bones and cancer.

You should not assume that because we have sunshine almost throughout the year you are getting enough of this vital vitamin. Some people living in the tropics are found to have a deficiency. Apart from sunshine, vitamin D is only found in a few foods. The best sources include oily fish such as mackerel and salmon, eggs and cod liver oil. You could also get it in form of supplements and most good multivitamins will include vitamin D.

How do you get vitamin D?

When the body gets exposed to sunlight, a chemical reaction beneath the skin converts cholesterol into vitamin D. The body needs 4,000iu of vitamin D a day for optimal health. This is ten times the recommended daily allowance of 400iu needed to prevent deficiency. People living in the tropics are unlikely to suffer from vitamin D deficiency unless they are confined indoors throughout, or are not getting enough sunshine, but you need to note that dark skinned people require longer hours of sun exposure.

Whereas fair skinned people need to be exposed to the sun for about an hour to generate 4,000iu, dark skinned people need about seven hours exposure to generate the same amount. As sunscreens block out UV light and vitamin D production, it is best to only apply them to areas likely to burn and when you expect to be in the sun for long hours. You should, however, avoid intense sunshine and never expose your skin to the point of burning.

What do researchers say?

*Vitamin D may boost your immune system. Scientists at Massachusetts General Hospital in the US found people with the lowest blood vitamin D levels were more likely to get colds and flu.

*Vitamin D cuts the risk of multiple sclerosis. According to scientists at Harvard School of Public Health in the US, taking vitamin D in a multivitamin cuts the risk of multiple sclerosis by 40 percent. Vitamin D regulates the level of calcium in the blood, which is vital for nerve impulse transmission.

*Vitamin D deficiency is linked to cancer. Researchers at NASA in the US studied cancer incidence in relation to sunlight exposure and found there were many cancer deaths linked to lack of sunlight.

*Vitamin D deficiency increases risk of diabetes. People with vitamin D deficiencies are at greater risk of diabetes and metabolic syndrome, a condition linked to poor blood sugar control, according to a study by Warwick University in the UK.

*Vitamin D reduces risk of fractures. Vitamin D plays an important role in laying down minerals in bone. In a study at Copenhagen University, middle-aged to elderly patients who took a daily supplement of vitamin D had a 20 percent less risk of fracture.

*Vitamin D deficiency increases risk of asthma. Low levels of vitamin D could increase asthma symptoms according to a study at Harvard Medical School. Children with the lowest levels of vitamin D were more likely to have been hospitalised for asthma than children with higher levels.

Published in February 2012