High Doses of Niacin May Increase Risk of Heart Disease: Study

Taking too much vitamin B3, also known as niacin, may increase the risk of cardiovascular disease, potentially resulting in heart attacks, strokes, and death, according to the findings of a new study.

Researchers from the Cleveland Clinic  warn that high doses of niacin increase inflammation in the blood vessels, which can increase the likelihood of suffering from heart disease and major adverse cardiovascular events (MACE). The findings were published February 19 in the journal Nature Medicine.

Niacin is an essential vitamin for the body, and deficiencies are linked to fatal conditions like pellagra. In response to those concerns, health officials began mandating foods in the American diet in the 1940s, which resulted in bread and cereal commonly being fortified with niacin or vitamin B3.

The recommended daily allowance of niacin is 16 mg per day for men and 14 mg per day for women. At one point, doctors prescribed niacin to help patients lower cholesterol levels, another factor linked to heart disease.

In this latest study, researchers looked at the impact of niacin on cardiovascular disease using clinical data, genetic data, and mouse data. They examined blood samples for more than 1,100 stable cardiac patients at a cardiology center.

The findings revealed excess niacin in the blood leads to the production of a substance called 4PY, which the researchers linked to an increased risk of cardiovascular disease. This led researchers to conduct two additional arms of the study, including a focus on 2,300 U.S. patients and 800 European patients with heart disease and a smaller study focusing on the effects in mice.

The data indicated excess niacin and the presence of 4PY accurately predicted an increased risk of major adverse cardiovascular events, including an increased risk of heart attack, stroke, and death. The higher the levels of 4PY, the more likely a person was to suffer a cardiac event.

When researchers injected mice subjects with 4PY, the mice experienced increased levels of inflammation in the blood vessels, which has been linked to an increased risk of heart disease, according to prior research.

Researchers said the findings of the new study should help change some of the overuse of niacin. They recommended that the food industry stop using niacin in food products, and that doctors should no longer recommend niacin for patients at risk for cardiovascular disease.

Since the vitamin is pro-inflammatory, researchers also called for changes in dietary recommendations for patients who may face a higher risk of suffering from heart attacks and strokes.