Vitamin D deficiency has been linked to cardiovascular disease and other conditions, but supplementing with too much D can reverse its benefits and even be harmful, according to a Johns Hopkins University study.
“Vitamin D is good to a certain level,” said lead author Dr. Muhammad Amer, an assistant professor of medicine at Johns Hopkins. “But don’t just keep on taking it. Have your blood drawn and your levels checked.”
Researchers who studied 15,000 people age 18 to 85 found that vitamin D supplementation reduced blood levels of C-reactive protein, or CRP, which is an indicator of a type of inflammation related to heart ailments. When the vitamin level exceeded 21 nanograms per milliliter, CRP was found to increase.
“The inflammation that was curtailed by vitamin D does not appear to be curtailed at higher levels of vitamin D,” said Amer. “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.”
The study was reported in the new issue of the American Journal of Cardiology.