Overweight kids often fall short on key nutrients — a paradox we call “overfed and undernourished.” New research links more body fat and faster weight gain among kids to low levels of vitamin D. This vitamin is technically a hormone — suggesting another hormonal aspect to excess body fat.

A study published in the American Journal of Clinical Nutrition tested vitamin D levels among 479 school children (ages 5 to 12) from Bogota, Colombia — then monitored weight and other measurements over the course of 30 months. They found that those with the lowest levels of vitamin D gained weight the fastest. Overall, children with the highest Body Mass Index (BMI) — e.g., the heaviest for their height — had 18% lower vitamin D levels than normal-weight kids. Study co-author Diane Gilbert-Diamond says such findings suggest “that low vitamin D status may put children at risk for obesity.” And vice versa: Vitamin D gets trapped in excess fat, and cannot easily escape to make it into the blood stream.

Vitamin D is gaining increased recognition for the vital role it plays in supporting various aspects of health. Since vitamin D is needed to utilize calcium, low levels can undermine bones and teeth. A University of California at San Diego study found increased vitamin D levels translated into lower rates of various cancers. Emerging research also links low levels of vitamin D to problems with chronic pain and emotional balance. Since our skin makes vitamin D upon exposure to the sun, winter’s waning rays mean at least 25% of adults are vitamin D deficient at this time of year. Six ounces of canned salmon provides 270% of your vitamin D needs, while six ounces of canned sardines provide 120%.

 Published January 1, 2011