Vitamin D deficiency linked to childhood obesity

The role of vitamin D is increasingly recognized as important for maintaining health, not only for metabolism of calcium in bone health, but also for other conditions as well. This fact makes the current widespread vitamin D deficiency all the more compelling, and a study published in the May issue of Journal of Adolescent Health has found that serious deficiency and insufficiency of vitamin D exist among obese adolescents.

The retrospective study, done at Hasbro Children's Hospital in Providence, RI, looked at blood levels of 25(OH) D for 68 obese adolescents, and found that all of the girls had low vitamin D, with 72 percent deficient and 28 percent insufficient. Among the boys, 91 percent had low levels, with 69 percent deficient and 22 percent insufficient.

Pediatrician Zeev Harel, lead author of the study, said, "It is possible that the association between obesity and low vitamin D status is indirect, arising from obese individuals having fewer outdoor activities than lean individuals, and therefore, less exposure to sun. Likewise, is it also possible that obese individuals do not consume enough foods that contain vitamin D." Other studies have also found a link between obesity and vitamin D deficiency, possibly from storage of vitamin D in fat tissue

The Hasbro Children's Hospital study also found a disturbing difficulty in treating the problem. About two thirds of the patients had follow-up measurements of vitamin D after treatment, and of that group, only 28 percent reached normal levels. The other patients did not attain a normal level even after multiple treatments.

Harel said of this problem, "The prevalence of low vitamin D status among obese adolescents in this study is greater than previously reported for this age group. It is concerning to us that only 28 percent of the adolescents were able to reach normal vitamin D levels through one course of treatment of the recommended dose of vitamin D, while the other 72 percent failed to normalize their levels even with repeat treatments."

All individuals with low vitamin D are at increased health risks. There is evidence linking healthy levels of vitamin D to protection against certain types of cancer, cardiovascular disease, and autoimmune disorders, as well as other diseases. Vitamin D is also thought to help boost the immune system to protect against infections. Adverse health conditions in adolescents have been found linked to low levels of vitamin D