The Sweet Spot for Vitamin D in Heart Health

BALTIMOREWhen it comes to heart health, the "Goldilocks" number for vitamin D appears to be 21 ng/ml of 25-hydroxyvitamin D [25(OH)D] in serum blood levels, according to a new study from Johns Hopkins University School of Medicine, Baltimore (Am J Cardiol. 2012 Jan 15).  Levels below or above that number were associated with an increase in serum C-reactive protein (CRP), an indicator of cardiovascular inflammation.

This echoes the finding of a study presented earlier this year at a scientific meeting of the American Heart Association (AHA). However, that previous study reported the "Goldilocks" zone was anything below 100 ng/mL of  25(OH)D in the blood.

In this current study, researchers  used data from the continuous National Health and Nutrition Examination Survey from 2001 to 2006, which included more than 15,000 adult participants. They reported CRP decreased by  0.285 mg/dl for each 10-ng/ml increase in 25(OH)D, below 21 ng/ml. However, an increase in 25(OH)D to above 21 ng/ml was not associated with any significant decrease in CRP. In fact, they said higher 25(OH)D levels were associated with an increase in CRP.

The inflammation that was curtailed by vitamin D does not appear to be curtailed at higher levels of vitamin D," said Study leader Muhammad Amer, M.D., an assistant professor in the division of general internal medicine at the Johns Hopkins University School of Medicine. Clearly, vitamin D is important for your heart health, especially if you have low blood levels of vitamin D. It reduces cardiovascular inflammation and atherosclerosis, and may reduce mortality, but it appears that at some point it can be too much of a good thing."

Amer and study coauthor Rehan Qayyum, M.D., M.H.S., also an assistant professor in the division of general internal medicine at Hopkins, said the biological and molecular mechanisms that account for the loss of cardiovascular benefits are unclear.