Dec 5, 2011 11:21 PM
Along with the low vitamin D levels, the obese children also had higher levels of what's called insulin resistance, meaning that they are no longer able to efficiently use insulin to convert sugars from foods into fuel for the cells. Type 2 diabetes occurs when the body either does not produce enough insulin or the cells become insulin resistant.
Researchers measured vitamin D levels in obese and normal-weight children, finding obesity to be associated with decreased vitamin D and increased insulin resistance.
Similar studies suggest the same association in adults, but the newly published research is among the first to examine vitamin D levels and diabetes risk factors in kids.
The findings suggest, but do not prove, that low vitamin D levels contribute to the development of type 2 diabetes, says Micah Olson, MD, who led the study as a clinical fellow at the University of Texas Southwestern Medical Center in Dallas.
Olson says studies are under way examining whether vitamin D supplementation lowers type 2 diabetes risk in people at high risk for developing the disease.
The study included more than 400 obese kids and teens between the ages of 6 and 16, and 87 normal-weight children and teens.
Obese children were more than three times more likely than non-obese children to be vitamin D deficient, and both obesity and low vitamin D levels were associated with higher degrees of insulin resistance.
Obese children were also more likely than non-obese children to skip breakfast and drink more soda and juice, suggesting that these lifestyle factors may contribute to lower vitamin D levels, the researchers noted.
Vitamin D is known as the sunshine vitamin because the body makes the vitamin when the skin is exposed to the sun.
Food sources of vitamin D include oily fish, eggs, fortified milk, and breakfast cereals.
Normal-weight children in the study had greater seasonal variations in vitamin D levels than obese children, suggesting that they had greater sun exposure.
The study appears in the latest issue of The Journal of Clinical Endocrinology & Metabolism.
Nutritional epidemiologist and diabetes researcher Susan Harris, DSc, of Tufts University and the USDA's Nutrition Center, says the current evidence suggests that vitamin D may help increase insulin production to help compensate for insulin resistance.
While it is not yet clear if vitamin D supplements reduce type 2 diabetes risk, Harris says it is clear that large segments of the population do not get enough vitamin D from the sun and food.