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Can Too Much Niacin Harm Your Heart?
July 17, 2024
Niacin, also known as vitamin B3, is widely used for its cholesterol-lowering effects and its role in heart health. However, the potential side effects and risks associated with high doses of niacin have raised concerns among health professionals and patients alike, and recent research links excessive niacin intake with heart issues.
A study published in February 2024 in Nature Medicine explored these issues in depth, shedding light on dangers of high levels of niacin — specifically that it raises the risk of heart attack, stroke and other dangerous cardiovascular disease (CVD) events.
Study: How Niacin Affects Heart Health
The study, conducted by researchers funded by the National Heart, Lung, and Blood Institute, had researchers collect blood samples from 1,162 stable cardiac patients (740 males, 422 females) “to screen for circulating small molecules whose levels could predict CVD event risks independent of traditional risk factors.”
After analyzing the blood samples, researchers found that 4PY, which is produced when there is too much niacin in the blood, was present in some of them. That led the researchers to dig further into data around heart disease events and the presence of 4PY.
They also examined 2PY, which comes from too much niacin in the blood too, since it showed up in some samples as well.
The scientists followed up with two more studies to validate the theory that 4PY (and 2PY) in the blood — due to too much niacin — can increase the risk of cardiovascular disease events. These studies evaluated data from 3,163 people who had heart disease or showed signs of CVD.
What did these follow-up studies reveal? It seemed that the people who had 4PY and 2YP in their blood samples had a greater chance of experiencing a stroke, heart attack or other negative cardiac event.
For even further understanding, the researchers then injected mice with 4PY and 2PY and discovered that 4PY raised inflammation in their blood vessels, another indicator of CVD risk.
This led the study authors to conclude: “Collectively, these results indicate that the terminal breakdown products of excess niacin, 2PY and 4PY, are both associated with residual CVD risk. They also suggest an inflammation-dependent mechanism underlying the clinical association between 4PY and MACE.”
According to one of the senior study authors, Stanley Hazen, M.D., Ph.D., chair of cardiovascular and metabolic sciences at the Cleveland Clinic’s Lerner Research Institute and co-section head of preventive cardiology at the Heart, Vascular, and Thoracic Institute, about a quarter of Americans have higher levels of niacin than is recommended.
The National Heart, Lung, and Blood Institute adds that “total niacin consumption in the U.S., through a mix of natural food sources, fortified foods, and supplementation, averaged 48 mg/d – more than triple the Recommended Daily Allowance,” from 2017–20.
“The main takeaway is not that we should cut out our entire intake of niacin—that’s not a realistic or healthy approach. Niacin is a vitamin and essential to our health,” Hazen told Health. “But an excess amount appears to be a concern.”
Niacin Side Effects/Symptoms of Niacin Overdose
Niacin is definitely a B vitamin that is essential to health, but as this study clearly shows, taking too much niacin can lead to serious health complications. It’s important to monitor your intake and avoid exceeding the prescribed amount.
The most common side effects of niacin include flushing, itching, nausea and headaches. These symptoms are often dose-dependent and can be mitigated by starting with a lower dose and gradually increasing it.
High doses should only be taken under the guidance of a health care professional.
Meanwhile, symptoms of a niacin overdose can include:
- severe flushing
- dizziness
- rapid heartbeat
- abdominal pain
- liver damage
It is crucial to avoid taking too much niacin and seek medical advice if experiencing these symptoms.
How much niacin per day should you consume? How much niacin is too much?
The recommended daily allowance for niacin is around 14–16 milligrams (mg) for adults and up to 18 mg for pregnant women. However, therapeutic doses for cholesterol management can be much higher, often ranging from 500 mg to 2,000 mg per day.
Dosages above 500 mg per day can pose significant health risks, including liver toxicity and glucose intolerance.
The study highlights the importance of adhering to recommended dosages and consulting with a health care provider if prescribed larger doses for cholesterol management purposes.
