Published on October 3, 2009, 12:00 am
Features
Recent research reveals an increased risk of vitamin D deficiency for people who frequently wear veils and those with darker skin.

The Medical Journal of Australia recommends that women who wear burkas and those with dark skin should be screened annually for vitamin D deficiency and vitamin D supplements should be provided to those at- risk in the population.

According to medical experts, people who keep their skin covered up preventing exposure to the sun are unlikely to obtain adequate levels of vitamin D from the sunlight. People of African and Asian descent are more vulnerable to vitamin D deficiency as the sun protecting melanin (skin pigment) in their skin hampers the production of vitamin D.

As melanin increases, the required period of exposure to ultraviolet B radiation increases as sunlight is needed to produce sufficient amounts of vitamin D. As a result, veiled people and people with dark skin require six times as much sunlight as those with pale complexions to produce the same levels of vitamin D.

Darker complexions provide greater protection against the UV rays of the sun in hot climates, whilst pale complexions allow higher levels of UV rays to penetrate the skin, allowing adequate absorption of vitamin in countries where there are dark winters without much sunlight, like the UK.

Vitamin D deficiency causes rickets in children, a disease where bone tissue fails to properly harden, resulting in soft bones and skeletal deformities. In adults, vitamin D deficiency can lead to osteomalacia and osteoporosis in adults resulting in weak bones and muscles.

Vitamin D deficiency also occurs when usual intake is lower than recommended levels over time, such as when the kidneys cannot convert vitamin D to its active form, or absorption of vitamin D from the digestive tract is inadequate. Vitamin D deficient diets are often associated with milk allergies, lactose intolerance, and a strict vegetarian diet.

Vitamin D, although known to promote healthy bones by regulating calcium levels in the body may have a broader role to in maintaining our health. Recently the scientific community has established evidence that strongly suggests it plays a part in protecting against autoimmune diseases, including multiple sclerosis and Type I diabetes, as well as asthma, hypertension and some forms of cancer.

Vitamin D is only present in a few foods and fatty fish is considered to be the best source. Some vitamin D is also present in beef liver, cheese and egg yolks. Most of the food sourced vitamin D in the western diet comes from fortified foods - where vitamin D is artificially added. The majority of our supply typically comes from exposure to ultraviolet rays in sunlight. Just how much vitamin D is needed and how they should get best to source it is under debate.

The fortification of food with vitamin D has made rickets a rare disease in western societies. However in the US rickets is still being reported, particularly amongst African American infants and children. In 2003 the state of Memphis reported 21 cases of rickets among infants, 20 of whom were African American.

A 1995 report by the US National Library of Medicine established that prolonged exclusive breastfeeding by mothers who are not vitamin D replete is the significant cause of rickets in African American infants. Increased use of sunscreen, less milk uptake and spending more time indoors watching TV and playing video games accounts for why children are 60 percent more likely to be Vitamin D deficient. People of African descent are also more likely to have lactose intolerance, restricting their intake of dairy products.

A In an article in USA Today in April 2009, Boston University professor Michael Holick, a leading vitamin D researcher, argues that lower vitamin D levels can contribute to the health gap between black and white Americans and could explain why African Americans have higher rates of prostate cancer, breast cancer and colon cancer and develop more aggressive forms of these cancers.

Clearly the debates and research around vitamin D and its benefits are raising important questions particularly for those who are in the greatest at risk category. Therefore further studies are still required that can clearly establish:

•Why getting vitamin D from fortified and nutritional sources are not effective for people of African and Asian descent.

•What the most effective supplement intakes of vitamin D are for each of the different at risk groups in the population.

•What overall health benefits can be gained by lowering the incidence of vitamin D deficiency in the population.

More research on a par with the US and Australia in the UK could provide a clearer picture of the impact that vitamin D deficiency for women who wear veils and those with darker skin, which given the growing populations within African and Asian communities should be a priority.