(NaturalNews) Why are American kids so often overweight and even downright fat to the point many are developing type 2 diabetes, a disease that used to be unheard of except among middle-aged folks? Is it all due to junk food diets and lack of exercise? Those factors no doubt contribute to the epidemic of childhood obesity, but now scientists have found another reason why countless youngsters may be too chubby -- a lack of vitamin D.
Research by University of Michigan (U-M) scientists just published in the American Journal of Clinical Nutrition revealed that kids who were deficient in vitamin D accumulated fat around the waist and gained weight more rapidly than youngsters who got enough vitamin D. The finding of abdominal fat accumulation is especially important because this central fat can cause a so-called apple shaped body -- a body type linked to increased risks of not only type 2 diabetes but other chronic conditions later in life, including cardiovascular disease.
For their study, epidemiologist Eduardo Villamor, associate professor at the U-M School of Public Health and senior author of the study, teamed up with colleagues at the National University of Colombia. The research (which began when Villamor was at Harvard) recruited 479 school children between the ages of 5 and 12 from Bogota, Colombia, in 2006. The youngsters were followed over the course of approximately 30 months.
Vitamin D levels were measured from blood samples taken at the beginning of the study. Of all the children tested, 10 percent were vitamin D deficient, and another 46 percent of kids had insufficient amounts of the vitamin in their blood (which indicated they were at risk of becoming deficient). Then, over time, the scientists looked for a link between the children's vitamin D levels and changes in three indicators of body fat: body mass index, waist circumference and subscapular-to-triceps skin fold ratio.
"We found that the kids with the lowest vitamin D levels at the beginning tended to gain weight faster than the kids with higher levels," Villamor said in a statement to the media. He also pointed out that the youngsters with the lowest vitamin D levels had the most dramatic increases in central body fat. What's more, a lack of vitamin D was associated with slower growth in height among girls, although this was not found to be true in boys.
"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."
In addition to getting adequate sun exposure, other sources of vitamin D include fortified foods and supplements. Villamor pointed out that not only may vitamin D possibly curb obesity in youngsters, but vitamin D supplementation has been shown to prevent some viral infections in school-age children, too.