Niacin is an essential B vitamin, but research reveals that too much of it may harm your heart. Excessive amounts trigger inflammation and damage blood vessels, scientists reported in the journal Nature Medicine.

“The average person should avoid niacin supplements now that we have reason to believe that taking too much niacin can potentially lead to an increased risk of developing cardiovascular disease,” said senior study author Dr. Stanley Hazen, chair of cardiovascular and metabolic sciences at the Cleveland Clinic’s Lerner Research Institute.

The recommended daily allowance of niacin for men is 16 mg per day and 14 mg a day for women who are not pregnant.

Ever since the 1940s, when grains and cereals began to be fortified with niacin, Americans have gotten plenty of the vitamin in their diet. The move to fortify those foods was prompted by evidence suggesting that very low levels of niacin could trigger the development of a potentially fatal condition called pellagra, said Hazen, who is also co-section head of preventive cardiology at the Heart, Vascular, and Thoracic Institute.