In sunny South Africa, one wouldn’t expect vitamin D deficiency to be commonplace – after all, it is the ‘sunshine vitamin’. But according to recent studies, vitamin D status in South Africa is not optimal, especially in black populations. While our bodies are capable of making vitamin D in the skin using ultraviolet light, it would seem that this doesn’t provide enough of the vitamin to prevent the symptoms of deficiency. Most notable of these is poor bone and dental health, but there is also evidence for susceptibility to heart disease and even tuberculosis.

Dr Zelda White of the University of Pretoria’s (UP) Micronutrient Nutrition Research Programme (MNRP) says that we don’t properly understand how age, body weight and body composition influence levels of serum 25-hydroxyvitamin D (the active form of the vitamin) in the blood. Her research is measuring body composition in two different ways, to better understand these relationships. “We’re investigating body composition using multifrequency bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA) to understand the relationship between body composition, vitamin D status and bone mass in children,” says White. DEXA is an expensive but accurate way to measure body composition, while BIA is cheaper and more convenient. However, multifrequency BIA has not yet been tested in children. White is looking at whether multifrequency BIA can be used in place of DEXA for this sort of work.

White got her PhD in Nutrition in 2006 from North-West University. After a brief stint in the private sector, she returned to lecture at UP in 2008. “I have a passion for research and enjoy the field of nutrition,” she says. “I train dietetic students in research and nutrition, as well as teaching and supervising postgraduate students.” Beyond comparing the two measures of body composition, White’s research project under the newly-established MNRP aims to identify factors linked to Vitamin D status in South African school-age children. This will help to “establish requirements for vitamin D intake.”'

She hopes that her work will identify factors associated with vitamin D status, “to optimise bone development during growth, and decrease risk for osteoporosis and other chronic disease later in life.” This could be achieved through diet intervention trials, and ultimately through fortification strategies, which have effectively limited iodine and iron deficiency in SA populations.

For more information, contact Dr Zelda White at [email protected]