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Is Too Much Niacin in Your Diet Bad for You?

New study finds link between high levels of the B vitamin, used to fortify bread and cereal, and cardiovascular risks


spinner image nutrition label with niacin circled under images of flour rice and wheat
Getty Images (2), AARP

A lifesaving nutrient added to foods since the 20th century to combat malnutrition may have an unintended impact on people’s health today.

Niacin, also known as vitamin B3, is critical to cell development and helps to convert the food you eat into the energy your body needs. But new research suggests that too much of this essential nutrient — found in meats, peanuts and fortified breads and cereals — could be harmful to the heart.

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A team of researchers studied blood samples from two groups of patients being evaluated for heart disease. They found a strong link between high circulating levels of a substance called 4PY, which is a byproduct of excess niacin in the body, and the development of a heart attack, stroke or other cardiac event.

Foods high in niacin

  • Beef liver
  • Chicken breast
  • Salmon
  • Beef
  • Pork
  • Canned tuna
  • Peanuts
  • Fortified breakfast cereals
  • Marinara sauce (ready to serve) 
  • Turkey breast
  • Brown rice

Source: NIH Office of Dietary Supplements 

Additionally, the researchers found that in mice, 4PY triggered inflammation in the blood vessels. This inflammation can lead to damage, including atherosclerosis, or the buildup of plaque in the artery walls. The study was published Feb. 19 in the journal Nature Medicine.

Lead researcher Stanley Hazen, M.D., says together the findings suggest that excess niacin is not just associated with an increased risk for heart disease but may also contribute to its development. The results could pave the way for treatments to reduce or prevent blood vessel inflammation, as well as diagnostic tools to help identify people who are getting too much niacin and may be at higher risk for a heart event, Hazen says.

Limiting processed foods could help avoid niacin overload

What is pellagra?

Pellagra is a disease that occurs when a person does not get enough niacin. Though rare in the U.S., it occurs in some less developed parts of the world. Symptoms of pellagra can include:

  • Diarrhea, stomach pain and indigestion 
  • Rash or discoloration on skin exposed to sunlight
  • Depression and loss of memory that can progress to paranoia
  • Anorexia

Source: NIH Office of Dietary Supplements and Cleveland Clinic

Niacin deficiencies were more common in the U.S. in the early 20th century around the time of the Great Depression. By the 1970s, niacin deficiencies and the complications that ensued — a disease known as pellagra — had become rare, says Hazen, chair of cardiovascular and metabolic sciences at Cleveland Clinic’s Lerner Research Institute.

“And that’s because so many things are fortified,” he explains. “[Niacin] literally is put in the flour we eat, the rice, the oats, the cereal.”

Americans are eating more of these products than ever, increasingly relying on ultra-processed foods, “much of which include refined fortified flour and cereals,” the study’s authors note. Niacin is also sold as a supplement and was once a go-to prescription treatment for high cholesterol, though research suggests it doesn’t add much benefit to statin therapy and can cause harmful side effects.

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Among the two groups of patients included in this latest study, 1 in 4 had high levels of niacin that could be linked to increased heart risks, Hazen says. The Office of Dietary Supplements at the National Institutes of Health says most people in the United States consume more than the recommended daily intake for niacin, which is 16 milligrams (mg) a day for men and 14 mg for women.

Given the results of the study, Hazen says people should talk to their doctor before taking an over-the-counter supplement. Research from AARP shows that nearly 80 percent of adults 50 and older take a vitamin or dietary supplement.

“The second thing I would say is to just focus on a diet rich in fruits and vegetables and avoid excess carbohydrates,” Hazen says. Approximately 60 percent of the American diet comes from processed foods, studies show.

Another possible outcome of the research is a larger conversation around the fortification of foods, especially as medicine evolves to become more tailored to each individual patient’s needs.

“Should there be [a nonfortified] option made available to people? Because right now it’s just one size fits all,” Hazen says. “At the time, it made a tremendous health benefit to a nation that was starving, essentially. But we’re not that same nation anymore.”

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