Low Vitamin D Levels Tied to Arterial Stiffness in Teens, Young Adults

June 28, 2013

By Anne Harding

NEW YORK (Reuters Health) Jun 28 - Low serum levels of vitamin D are an independent risk factor for arterial stiffness in obese youth, new findings show.

"It's possible that if we optimize the serum vitamin D levels in these youth, their arterial stiffness might improve, and if the arterial stiffness improves that may improve the overall cardiovascular mortality profile in this population," Dr. Pranati Jha, one of the study's authors and a pediatric endocrinology fellow at the Cincinnati Children's Hospital Medical Center, told Reuters Health. Dr. Jha presented the findings at The Endocrine Society's Annual Meeting in San Francisco this month.

Arterial stiffness is a known risk factor for vascular disease in adults and children, and studies have shown an inverse relationship between serum levels of vitamin D and arterial stiffness in healthy adults, obese adults, and obese adults with type 2 diabetes, Dr. Jha and her team note in the abstract of their study.

To investigate whether low serum vitamin D might be associated with arterial stiffness in adolescents and young adults as well, the researchers looked at stored samples for 570 youths participating in The Cardiovascular Disease in Youth with Type 2 Diabetes Study, which was conducted at Cincinnati Children's Hospital between 2004 and 2010. The group included 190 type 2 diabetes patients, 190 obese controls without diabetes, and 190 healthy, lean, non-diabetic controls. The average age was 18, 55% were African American, and 34% were male.

According to the National Institutes of Health Office of Dietary Supplements, a serum 25-hydroxyvitamin D concentration of 20 ng/mL or higher is generally considered adequate for bone and overall health in healthy individuals.

Among lean youth, mean 25(OH)D concentrations were 21.27 ng/mL, while they were 14.29 ng/mL for obese, non-diabetic youth and 14.13 ng/mL for the obese individuals with type 2 diabetes (p<0.001). Average pulse wave velocity was 5.30, 6.29, and 6.64 m/s, respectively, for the lean, obese, and type 2 diabetic youth (p<0.001).

Spearman correlations showed an inverse relationship between serum vitamin D levels and arterial stiffness for each of the three groups. The correlation coefficient (r), which indicates the strength of the relationship, was -0.2616 (p<0.001) for the lean youth, -0.2706 (p<0.001) for the obese youth, and 0.3607 (p<0.001) in the young people with type 2 diabetes.

Serum vitamin D levels are known to be lower in obese individuals, in part because fat cells accumulate vitamin D, and also possibly because obese people may spend less time outdoors and are also likely to be eating a less-than-optimal diet, Dr. Jha told Reuters Health.

Given that vitamin D has been shown in animal studies to have antiproliferative and anti-inflammatory effects, she added, it's plausible that people with lower levels of serum vitamin D could have chronic vascular inflammation and accelerated proliferation of smooth muscle cells in the blood vessels, which would accelerate arterial stiffening.

Dr. Jha and her colleagues are now planning a clinical trial in young people to determine if vitamin D supplementation will help reduce arterial stiffness.

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