Why treating obesity in teens with vitamin D might not make much sense


Plate of vitamin D

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With obesity in teens and adolescents reaching apparently epidemic proportions, some are looking to radical solutions for their kids. Vitamin D has been linked to improvements in health for young people who carry too much weight. However, according to a new report by the Mayo Clinic, giving obese teens high doses of vitamin D could actually do a lot more harm than good.


Study in D


Some observational studies have suggested connections between vitamin D deficiency and weight-related medical conditions — that is, linking levels of vitamin D in the blood and improved vascular function cardiovascular diseases and insulin resistance. With a third of American adolescents overweight and around a fifth obese — according to the Journal of American Medical Association — care providers often use high-dose supplementation in an attempt to slow or reverse some of the clinical complications associated with obesity.

Now a team led by Dr. Seema Kumar, a pediatric endocrinologist in the Mayo Clinic Children's Center who has been studying the effects of vitamin D supplementation in children for 10 years, say they have evidence that shows adolescents only get limited benefit from vitamin D supplements. The latest study — published online in the journal Pediatric Obesity — suggests that there are no significant gains for heart health or diabetes risk. In fact, the researchers say, large amounts of the vitamin could mean an increase in cholesterol and fat-storing triglycerides.


Too much of a good thing


It is possible to ingest too much vitamin D, says Kumar — patients can develop a condition called vitamin D toxicity or hypervitaminosis, which can result in poor appetite, nausea, vomiting and kidney complications. According to the Vitamin D Council, toxicity occurs when you ingest 40,000 IU — that's just 1/1000 of a gram — per day for a couple of months or longer, or take a very large one-time dose. Too much vitamin D can also lead to a condition called hypercalcemia, which causes nausea, loss of appetite, thirst, confusion and tiredness, constipation or diarrhea and abdominal pain.

Kumar opted to study vitamin D in overweight teens because they are at increased risk for chronic disease and because of the increasing popularity of the supplement as a homeopathic or complementary treatment for obesity.Care providers have begun to put obese children on large courses of vitamin D, says Kumar, sometimes more than five or ten times the recommended daily intake.


Mixed results


"I have been surprised that we haven't found more health benefit," says Kumar. "We're not saying it's bad to take vitamin D supplements at reasonable doses, and we know most obese teens are vitamin D deficient. We're just saying the jury is still out on how useful it is for improving overall health in adolescents." Despite the results, Kumar advises caution. She admits her findings could be attributed to the relatively small number of children who participated in the study as well as the short timeframe. She says larger, placebo-controlled studies to examine the long-term effects of vitamin D supplementation on teens and children could provide more accurate results.

"After three months of having vitamin D boosted into the normal range with supplements, these teenagers showed no changes in body weight, body mass index, waistline, blood pressure or blood flow," says Dr. Kumar. "We're not saying the links between vitamin D deficiency and chronic diseases don't exist for children — we just haven't found any yet."


A supplement supplanted


It's widely known that too little vitamin D is bad for bones, causing them to weaken. But taking an increased amount has been suggested at various times for the treatment of multiple sclerosis, Alzheimer's Disease and hypertension — with mixed credibility. Even when there is some scientific evidence behind the claims, the advice remains the same: excessive amounts do not guarantee exceptional success. Seek professional medical advice when making any big decisions about health matters.

As previous studies have shown, adolescents and teenagers are at a particularly sensitive point when it comes to weight and body image. It would be as imprudent to take these results as definitive as it would to imagine that apparent links between vitamin D intake and the treatment of obesity mean you should start shoveling down the pills. But it clearly shows how susceptible we can be to suggestions of seemingly miraculous cures and how eager we can be to look for a "magic bullet" rather than take a sensible and measured approach to health.