Excess Niacin Linked to Heart Disease, Research Suggests

February 22, 2024

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High levels of niacin — an essential B vitamin — may increase heart disease risk, new research suggests. A once-prescribed supplement to help lower cholesterol, it may trigger inflammation, damaging blood vessels.

The report, published in Nature Medicine, revealed a previously unknown risk from excessive amounts of the vitamin. Most people get enough niacin through diet, as it’s in foods such as poultry, fish, nuts, legumes, and fortified cereals and breads. Niacin is also included in multivitamins.

According to the Mayo Clinic, the recommended daily allowance of niacin for men is 16 milligrams per day, 14 milligrams for women who are not pregnant.

Despite these recommendations, about 25% of Americans have higher than the recommended levels of niacin, according to the study’s senior author, Dr. Stanley Hazen, chair of cardiovascular and metabolic sciences at the Cleveland Clinic Lerner Research Institute and co-section head of preventive cardiology at the Heart, Vascular, and Thoracic Institute.

While the study did not nail down a threshold for niacin to turn into a risk, researchers hope future research will draw the line between healthy and unhealthy amounts.

“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,” Hazen told NBC News.

When conducting the study to search for unknown risk factors for cardiovascular disease, Hazen and his research term designed a multipart study (clinical data, genetic data, and mouse data) that included an analysis of fasting blood samples from 1,162 patients who had come into a cardiology center to be evaluated for heart disease.

Researchers discovered a substance, named 4PY, in some of the blood samples that is only made when there is excess niacin.

After the discovery, researchers conducted two additional “validation” studies, which included data from a total of just over 3,000 adults who either had heart disease or were suspected of having it. The two studies, one in the U.S. and one in Europe, showed that 4PY levels predicted future risk of heart attack, stroke, and death.

For those looking to monitor their niacin intake, Megan Huff, an Atlanta-based cardiac ICU dietitian, recommends paying attention to intake levels of certain foods like fortified cereals and breads, along with poultry, fish, brown rice, and peanuts.

“With 10.3 milligrams of niacin per 3-ounce serving, chicken has one of the highest amounts of niacin. Fortified cereals are also high in niacin,” Huff says.

Huff also says that several supplements contain “way more than the daily recommended value of niacin. For example, a typical niacin supplement contains 300 to 500 milligrams of niacin, which is 1875% to 3,125% of the daily value. The NIH states that the daily upper limit of niacin [for adults] is 35 milligrams. Always make sure to check with your doctor before starting a supplement.”