Excess amounts of this B vitamin linked to higher heart disease risk

About 1 in 4 Americans have too much niacin in their body from eating meats and nuts, but some people are still taking it as a supplement.

Having vitamin deficiencies can harm your health, but consuming too much of them can also hurt you — specifically, your heart.

Researchers with the Cleveland Clinic found having high levels of niacin, also called vitamin B3, is strongly associated with a higher chance of developing heart attack, stroke and other adverse cardiac events.

The findings, published in Nature Medicine on Monday, were the result of large-scale clinical studies that found highly circulating levels of 4PY, a breakdown product of excess niacin, directly triggered vascular inflammation, which can damage blood vessels and, over time, lead to atherosclerosis — the build-up of cholesterol plaque in and on artery walls .

Niacin is a common vitamin found in many foods, including meat, fish, nuts, grains and cereals, according to the National Institutes of Health. Eating these foods allows most Americans to consume enough of the vitamin, especially because niacin fortification in "staple foods" like flour and oats has been mandated in the U.S. since the 1940s to prevent deficiency-related health effects, the study noted.

But even though niacin deficiency is a rarity in the U.S., some people do take it as a dietary supplement or as a prescription, particularly those who don't eat enough iron-rich foods and those who use it to treat high cholesterol.