Vitamin D deficiency in black and white

Vitamin D has long been recognised as vital to skeletal health, and the high levels of deficiency among women of childbearing age is a major cause for concern. This is because a lack of the vitamin in these women can result in the inadequate transfer of maternal vitamin D to the foetus during pregnancy, which in turn can lead to low infant stores of the nutrient.

A number of high profile reports about the growing incidence of rickets - a disease caused by the lack of vitamin D or hypovitaminosis D - among African American children prompted a team of researchers from the US National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP), led by Shanna Nesby-O'Dell, to investigate the levels of vitamin D deficiency among black women of childbearing age and to compare them to white women of the same age.

Writing in the American Journal of Clinical Nutrition​, Nesby-O'Dell's team found that the African American women had a much higher incidence of hypovitaminosis D than white women, and that this in turn was leading to the higher levels of deficiency among African American children.

The team examined 1546 African American women and 1426 white women aged 15 to 49 years between 1988 and 1994. They found that hypovitaminosis D was 10 times more prevalent in African American (42 per cent) than in white women (4 per cent).

Nesby-O'Dell said that they also discovered that every determinant of vitamin D status contributed in some part to the prevalence of hypovitaminosis D in the African American women, including urban residence, increased skin melanin with low rates of casual sunlight exposure and low consumption of fortified milk and cereal.

Even those African American women who consumed adequate intakes of vitamin D from supplements had hypovitaminosis D, indicating, the researchers said, that the standard 200-400 IU/day found in most vitamin supplements may be inadequate for these women.

The full text of the research can be read here​.