Niacin May Increase Heart Disease Risk, Study Suggests: What To Know

Topline

A common vitamin called niacin may increase the risk of heart disease, a new study suggests, though complete elimination of niacin from the diet isn’t necessary, and researchers say more regulation may be needed.

A niacin (vitamin B3) capsule.

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Key Facts

High levels of niacin may cause inflammation and damage blood vessels, increasing the risk of heart disease, a study published Monday in Nature Medicine suggested.

The researchers looked at two different study populations—one group of about 1,200 patients who were being evaluated for heart disease, and a second group of over 3,000 people who had heart disease or were suspected of having it—which confirmed high levels of 4PY, a broken down niacin substance, were linked to a risk of heart attack, stroke and other adverse cardiac events.

One in four study participants consumed too much niacin and had high levels of 4PY; the study also injected mice with 4PY and found it increased inflammation in the rodents’ blood vessels.

Niacin, or vitamin B3, is a vitamin commonly found in popular multivitamins and foods like beef, pork, fish, poultry, flour, bananas, some cereals, nuts, seeds and breads, and previously was widely used to treat high cholesterol, according to the Harvard T. H. Chan School of Public Health.

The recommended daily amount of niacin for adult men is 16 milligrams, 14 milligrams for adult women, 18 milligrams for pregnant teens and women and 17 milligrams for breastfeeding teens and women.

Because niacin is very common in Western diets, most Americans get enough niacin from their foods, so there isn’t a need for it in supplements, according to the study.

Crucial Quote

“The main takeaway is not that we should cut out our entire intake of niacin—that’s not a realistic approach,” Stanley Hazen, senior author and chair of cardiovascular and metabolic sciences at the Cleveland Clinic’s Lerner Research Institute, said in a statement. “Given these findings, a discussion over whether a continued mandate of flour and cereal fortification with niacin in the U.S. could be warranted.”

Key Background

Scientists discovered in the 1940s that niacin deficiency causes a deadly form of malnutrition called pellagra, so they began including the vitamin in foods like flours and cereals, according to the National Institutes of Health. Around three million Americans contracted pellagra, and 100,000 died between 1907 and 1940. Doctors began using niacin to treat patients with high cardiovascular risk and to lower low-density lipoproteins (LDL) cholesterol, but more recent studies found the vitamin offered disappointing results. This caused researchers to conclude it had no beneficial effect on patients already taking cholesterol-lowering statins. A previous study suggested a link between niacin and inflamed blood vessels after some patients taking the vitamin continued having strokes and heart attacks, even though the niacin lowered cholesterol levels. The complex relationship between niacin and heart health has left scientists perplexed for years. “Despite niacin lowering of cholesterol, the clinical benefits have always been less than anticipated based on the degree of LDL reduction,” which led to the belief that too much niacin came with “unclear” adverse effects, Hazen said. However, the researchers believe their new findings better explain this relationship, and “why investigating residual cardiovascular risk is so critical.”

Tangent

Niacin is a water-soluble vitamin, meaning the body doesn’t store it, according to the Mount Sinai Health System. High niacin levels can cause headaches, diarrhea, gout, dizziness, blurred vision, diabetes, rapid heart rate, upset stomach, itching, liver damage and flushing of the skin. Serious side effects are more common if between 2,000 to 6,000 milligrams of niacin is taken a day.

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