Biography
Biography: Afrozul Haq
Abstract
Obesity is a significant health problem world-wide and the increase in obesity rates presents a major public health concern. Vitamin D deficiency is another pandemic and has been implicated in several diseases including obesity, cardiovascular risk, metabolic syndrome and many non-skeletal diseases. The role of vitamin D in calcium and bone metabolism is well established. Hypovitaminosis D is well-documented in those who have had bariatric or gastric bypass procedures, in which a malabsorptive state is deliberately induced, but there is no evidence that obesity itself results in reduced absorption of dietary vitamin D. Given that vitamin D is fat-soluble and that calcium absorption has been shown to be increased in diets high in fats, it is unlikely that obesity affects vitamin D-calcium homeostasis through altered gut absorption. The association between reduced 25(OH)D concentrations and obesity is well established. Correction of low 25(OH)D concentrations in obese individuals requires higher doses than those often advocated for the general population (may be the Endocrine Society Guidelines for Vitamin D Supplementation). There are plausible mechanisms and some in vitro evidence supporting a role for vitamin D in weight reduction, with the proviso that it may be difficult to determine which effects are due to vitamin D itself and which are mediated via calcium. There is a clear need for adequately-powered, prospective interventions which include baseline measurement of 25(OH)D concentrations and involve adequate doses of supplemental vitamin D. Until such studies have been reported, the role of vitamin D supplementation in obesity prevention remains uncertain.