THURSDAY, Aug. 5 (HealthDay News) -- Black teens can gain a measure of protection from heart disease by taking daily vitamin D supplementation at levels that are five times the current recommendations, new research suggests.

Specifically, high amounts of vitamin D at doses of 2,000 International Units (IU) per day appears to spur an increase in the flexibility of blood vessels while alleviating arterial stiffness among black youth in the United States, the study authors reported.

The finding was released online in advance of publication in an upcoming print issue of the Journal of Clinical Endocrinology & Metabolism, by a team of researchers from the Medical College of Georgia (MCG) Georgia Prevention Institute.

Vitamin D deficiency can lead to depressed mood and energy levels, weakened bones and cardiovascular complications. The study authors noted that blacks generally face a higher risk for serious heart disease, while also facing difficulties in absorbing vitamin D from sun exposure due to dark skin pigmentation.

At the moment, the recommended dose for vitamin D consumption is set at 400 IUs per day, with 2,000 IUs per day considered to be the upper limit for safety, noted study author Dr. Yanbin Dong, a geneticist and cardiologist at the Georgia Prevention Institute, and co-director of the MCG Diabetes and Obesity Discovery Institute.

Dong and his colleagues tracked vitamin D consumption among 44 vitamin D-deficient black teens living in Augusta, Ga., a region with a great deal of sunlight.

Participants were given either 400 IUs or 2,000 IUs over a four-month period, during which blood levels of the vitamin were monitored.

While experiencing some increase in vitamin D blood levels, none of the teens who took just 400 IUs reached vitamin D sufficiency, the authors observed.

Those children taking 2,000 IUs per day developed no toxic complications as a result, while appearing to benefit from the fact that those with the highest vitamin D levels developed the most flexible blood vessels. In turn, such increased flexibility can diminish the risk for high blood pressure and narrowing of the arteries, the team noted.

Cardiologist Dr. Paul Underwood, the Phoenix-based past president of the Association of Black Cardiologists, described the study as "unsurprising, but useful."

"In the past we had not considered African-Americans to be a group that was particularly at risk for vitamin D deficiency," he noted. "In fact, I personally had believed that vitamin D was a non-issue for this community among those with enough exposure to sunlight and a healthy diet," he explained.

"But recently this accepted idea has been the subject of a lot of debate and discussion," Underwood noted. "So I think studies of this kind -- studies that look at racial variations in terms of both the genetic and social roots of risk -- need to be done, because they challenge the misconception that vitamin D deficiency is a non-issue among this group.

More information

For more on vitamin D, visit the U.S. National Institutes of Health.