Vitamin D deficiency may increase the risk for inflammatory diseases

According to a new study from China school children with vitamin D deficiency have an elevated risk of developing diseases caused by higher levels of obesity and oxidative stress.

The observational study measured serum vitamin D concentrations, serum lipids, glucose metabolism indi- cators, inflammatory molecules and oxidative stress markers as well as the body height and width of a total of 1488 school children aged 7 to 11 years (1). The study results showed that almost 80% of the children had suboptimal vitamin D concentrations, including 56% being vitamin D deficient (below 20 ng/mL). The vitamin D deficient children had significantly higher body weight, a higher body mass index, a larger waist circumfe- rence and a higher percentage of body fat, compared to children with sufficient vitamin D levels. In addition, the vitamin D deficient participants had significantly lower concentrations of an antioxidant enzyme (super- oxide dismutase), indicating a weak antioxidation ability, and higher levels of inflammatory markers.

The researchers commented that children are one of the high-risk groups for vitamin D deficiency. Even in countries with significant sunshine, vitamin D deficiency in children is commonly found. Obesity and vitamin D status are known to be associated in adults. However, the causal relationship between them is still con- troversial. Some studies suggested that vitamin D deficiency was influenced by obesity. It was hypothesized that individuals with abnormal weight were susceptible to vitamin D deficiency, because circulating vitamin D is sequestered by excess body fat (2). On the other hand, some other studies reported that vitamin D defi- ciency promoted adiposity: vitamin D deficiency led to elevated parathyroid hormone, which might promote calcium influx into fat cells and thus stimulate the synthesis of fatty acids (3).

1. Zhang H.-q. et al. Vitamin D status and its association with adiposity and oxidative stress in school children. Nutrition. Published online March 2014.
   
2. Wortsman J. et al. Decreased bioavailability of vitamin D in obesity. The American journal of clinical nutrition. 2000; 72:690-693.
   
3. McCarty M.F. and Thomas C. A. PTH excess may promote weight gain by impeding catecholamine-induced lipolysis-implications for the impact of calcium, vitamin D, and alcohol on body weight. Medical hypotheses. 2003; 61:535-542.