Feb. 20, 2024 – Taking a B vitamin supplement that contains niacin could put people at an increased risk of heart disease. 

Led by researchers from the Cleveland Clinic, the study, published in the journal Nature Medicine, showed that as many as 1 in 4 people have a higher-than-recommended level of niacin. (Niacin is also called Vitamin B3 or nicotinic acid, and once was recommended to lower cholesterol, until statin drugs proved to be more effective.)

But when the body breaks down niacin, it creates a byproduct called 4PY that triggers inflammation in the body’s circulatory system. That inflammation damages blood vessels and, ultimately, can lead to buildup called atherosclerosis, which significantly raises the risk of a stroke, heart attack, or other major heart problem.

“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,” senior author Stanley Hazen, MD, PhD, chair of cardiovascular and metabolic sciences at the Cleveland Clinic’s Lerner Research Institute, said in a statement.

The researchers did the study because they suspected unknown risks of heart disease existed, since the condition persists even in people who follow all recommended preventions like eating healthy, exercising, drinking less alcohol, and managing weight, blood pressure, and blood sugar. Heart disease is the leading cause of death in the U.S., contributing to 1 in 5 of all deaths in 2021.

For the study, researchers analyzed the blood of several thousand people, first in people who were stable but being monitored for heart problems, and later in a more broad population. All of the analyses pointed toward higher risks of heart problems linked to excess niacin.

The findings help demystify a medical mystery that drew concern about using niacin to treat high cholesterol. People who took the supplement sometimes had a higher risk of diabetes, brain bleeding, skin problems, and gut problems. Ultimately, the supplement could help lower cholesterol, but problems with the heart and blood vessels continued in a puzzling way that scientists called “the niacin paradox.”

“Niacin’s effects have always been somewhat of a paradox,” Hazen said. “Despite niacin lowering of cholesterol, the clinical benefits have always been less than anticipated based on the degree of LDL reduction. This led to the idea that excess niacin caused unclear adverse effects that partially counteracted the benefits of LDL lowering. We believe our findings help explain this paradox. This illustrates why investigating residual cardiovascular risk is so critical; we learn so much more than what we set out to find.”

Niacin has been added to products like flour and fortified cereals since the Great Depression era of the early and mid-20th century, when a lack of niacin led to a health condition called pellagra. Symptoms of pellagra include skin problems, diarrhea, and dementia, and it can be deadly.

“The main takeaway is not that we should cut out our entire intake of niacin – that’s not a realistic approach,” Hazen said. “Given these findings, a discussion over whether a continued mandate of flour and cereal fortification with niacin in the U.S. could be warranted.”