As American children spend more time inside suffering from Nature Deficit Disorder, their natural exposure to vitamin D from sunlight is reduced.  The importance of vitamin D in preventing rickets has been known since the 1940s when milk fortification began.  Recent information on the flu prevention qualities of vitamin D has been touted showing supplementation is more effective than influenza vaccination.

A recent study has found another health problem linked to vitamin D deficiency:  childhood obesity.

Conducted at the University of Michigan and published in the American Journal of Clinical Nutrition, the study followed 497 school children in Bogota, Colombia, an area that sees plenty of sunshine throughout the year.

Green Parenthood reports:

The study mainly focussed on the accumulation of abdominal fat which is associated with several health hazards including diabetes and cardio vascular diseases…

The children with the lowest vitamin D levels gained weight faster than the children with higher levels of vitamin D. The central body fat increased significantly in children with lowest vitamin D levels. Lack of vitamin D also correlated with slower growth of height among girls, however, the same was not true in the case of boys.

Childhood obesity has been linked to inactivity, junk food, and even BPA.  Lack of outside activity, as well as the overuse of sun protection, and a poor diet could definitely contribute to vitamin D deficiency.  As the University of Michigan study demonstrates, living in a warm climate does not ensure vitamin D absorption from the sun at adequate rates.  Natural News reports:

“Interestingly, Bogota, Colombia, is in a subtropical zone where one may not expect to find a lot of vitamin D deficiency since the assumption is that sunlight is abundant there, but there could be many reasons people in subtropical climates may not get enough sun exposure,” Villamor added. In fact, earlier studies have shown that people in other subtropical areas, including Sao Paulo, Brazil, and Costa Rica, may also be at risk for vitamin D deficiency.

“Our findings suggest that low vitamin D status may put children at risk of obesity,” Diane Gilbert-Diamond, Villamor’s former Harvard student who is now at Dartmouth Medical School and was first author of the study, said in the press statement. “This is significant because vitamin D insufficiency is highly prevalent across the globe and childhood obesity rates are dramatically increasing worldwide.”

I don’t believe vitamin D deficiency alone explains the rising rates of childhood obesity. Poor diet, such as the standard American diet that is rich in calories but poor in nutritional content, combined with a more sedentary lifestyle, are most likely the culprits. These factors also contribute to vitamin D deficiency.  Like any aspect of human (and planetary) health, the circumstances cannot be looked at in isolation. A holistic approach gives us a better understanding.