Niacin, also known as vitamin B3, is an essential nutrient that plays a role in many bodily functions, such as energy production, DNA repair, and cholesterol regulation. It is naturally found in foods such as meat, fish, nuts, and grains, and is also added to fortify cereals and breads.
Most people get enough niacin from their diet, but some may take supplements to treat certain conditions, such as high cholesterol, pellagra, or niacin deficiency.
However, a new study published in Nature Medicine suggests that taking too much of this vitamin may have harmful effects on the heart, by increasing inflammation and damaging blood vessels.
The study, led by Dr. Stanley Hazen from the Cleveland Clinic, found that excess niacin intake leads to the production of a metabolite called 4PY, which is associated with a higher risk of cardiovascular diseases.
The study involved four parts: first, the researchers analyzed fasting blood samples from 1,162 patients who were evaluated for heart disease at a cardiology center, and identified 4PY as a marker of niacin excess.
Second, they validated their findings in two large cohorts of 3,163 patients from the U.S. and Europe, who were followed for an average of six years. They found that higher levels of 4PY predicted a higher risk of cardiovascular events, independent of other risk factors.
Third, they conducted experiments in mice, and showed that injecting 4PY increased inflammation and oxidative stress in their blood vessels. Fourth, they measured the dietary niacin intake of 2,257 healthy volunteers, and found that about 25% of them had excess niacin, mostly from fortified foods and supplements.
The researchers concluded that excess intake may be a previously unrecognized risk factor for cardiovascular disease, and that 4PY may be a useful biomarker to identify and monitor patients with niacin excess. They also suggested that reducing its intake or blocking 4PY production may be potential strategies to prevent or treat cardiovascular disease.
However, the study has some limitations and does not prove a causal relationship between niacin and cardiovascular disease. For example, the study did not account for other sources of 4PY, such as tobacco smoke, alcohol, or medications.
The study also did not measure the actual niacin intake of the patients, but relied on self-reported dietary data or blood levels of niacin and 4PY. Moreover, the study did not compare different forms or doses of niacin supplements, which may have different effects on the body.
Therefore, more research is needed to confirm the findings and to determine the optimal level and type of niacin intake for heart health. Until then, experts advise caution and moderation when it comes to niacin consumption, and recommend consulting a doctor before taking any supplements.
Niacin is still an important vitamin, but too much of it may be a double-edged sword for the heart.
