Vitamin D deficiency is much more frequent among African American children and adults than previously thought, according to researchers speaking at a recent meeting.
In one study, the researchers from the National Institute of Child Health and Human Development found nearly 65 per cent of obese African Americans were vitamin D deficient, particularly African American women. Vitamin D is increasingly being seen as a vital nutrient to protect post-menopausal women from fractures associated with osteoporosis.
In the study, researchers compared the levels of vitamin D deficiency in overweight African American and Caucasian subjects. Many of the subjects with vitamin D deficiency were also found to suffer from secondary hyperparathyroidism (a condition that occurs when the parathyroid gland produces too much parathyroid hormone, causing fatigue, disorientation, and depression)as a result of their low levels of vitamin D.
"We already know that dark skin pigment and increased body weight put people at higher risk for developing vitamin D deficiency," said Dr Shamik Parikh, a clinical investigator at the National Institute of Child Health and Human Development."Our findings suggest that obese African Americans, especially women, should be regularly screened for vitamin D deficiency."
In adults, low levels of vitamin D can be responsible for low dietary calcium absorption while during adolescent years vitamin D deficiency can have a negative impact on bone density.
In another study, researchers measured vitamin D levels in more than 200 adolescents. Eighteen per cent of the subjects tested positive for vitamin D deficiency, which was equal in boys and girls, but more prevalent in African Americans and during the winter months. Researchers also discovered a correlation between lifestyle variables and vitamin D deficiency.
"Adolescents who took vitamins as well as calcium supplements and exercised regularly were less likely to suffer from vitamin D deficiency," said Dr Catherine Gordon, an endocrinologist at Children's Hospital in Boston. "Our findings suggest that vitamin D deficiency is common among adolescents. It is critical that we find ways to help adolescents maintain healthy levels of vitamin D to avoid skeletal problems as they age."
Doctors in the US recently advised that the recommended levels of vitamin D for infants be increased because exposure to sunlight, which generates production of the vitamin in the skin, is no longer a safe way to prevent deficiency in children.
The reserachers were speaking at the annual meeting of the Endocrine Society taking place in Philadelphia on Friday.