Minn. ó Dosing obese teens with vitamin D shows no benefits
for their heart health or diabetes risk, and could have the
unintended consequences of increasing cholesterol and
fat-storing triglycerides. These are the latest findings in a
series of Mayo Clinic studies in childhood obesity.
Kumar, a pediatric endocrinologist in the Mayo Clinic Childrenís
Center, has been studying the effects of vitamin D
supplementation in children for 10 years, through four
clinical trials and six published studies. To date, Dr. Kumarís
team has found limited benefit from vitamin D supplements in
adolescents. The latest study, Effect of Vitamin D3 Treatment
on Endothelial Function in Obese Adolescents, appears online
in Pediatric Obesity.
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. "Weíre not saying the links
between vitamin D deficiency and chronic diseases donít
exist for children ó we just havenít found any yet."
five American adolescents is obese, and more than a third are
overweight, according to the Journal of American Medical
Association. Several observational studies also have noted
links between vitamin D deficiency and a host of
weight-related medical complications, including cardiovascular
diseases and insulin resistance. As a result, caregivers and
providers often start high-dose supplementation in an attempt
to slow or reverse some of the clinical complications
associated with obesity.
have been surprised that we haven't found more health
benefit," says Dr. Kumar. "Weíre not saying itís
bad to take vitamin D supplements at reasonable doses, and we
know most obese teens are vitamin D deficient. Weíre just
saying the jury is still out on how useful it is for improving
overall health in adolescents."
the first of Dr. Kumarís studies to report increased
cholesterol and triglycerides during vitamin D
supplementation, a finding she says might be attributed to the
smaller number of children who participated in the study and
the relatively short time frame. She calls for larger,
placebo-controlled studies to examine the long-term effects of
vitamin D supplementation on teens and children.
and providers often put obese adolescent children on vitamin D
regimens ó sometimes at more than 5-to-10 times the
recommended daily intake ó because some studies have shown a
link between vitamin D in the blood and improved vascular
function, says Dr. Kumar. She opted to study vitamin D in
overweight teens because this population is at increased risk
for chronic disease, and because of the compoundís
increasing popularity as a homeopathic or complementary
treatment for obesity.
Kumar notes that it is possible to ingest too much vitamin D,
a condition called vitamin D toxicity or hypervitaminosis,
which can result in poor appetite, nausea, vomiting and kidney