What Is Niacin?

Niacin, a form of vitamin B also called nicotinic acid or B3, is essential for proper cell function. Niacin is water-soluble, which means it is quickly absorbed in water and available for immediate use by your body. However, your body does not store niacin, so you should consume it regularly.

Niacin deficiency is rare in the U.S. because it is readily available in many foods, including meat, legumes, and grains. However, some people may have trouble getting enough niacin, especially those who are malnourished due to a health condition. In these cases, niacin supplements may be beneficial.

This article looks at the use of niacin and its different forms. It also discusses side effects and dosage.

Dietary supplements are not regulated in the United States, meaning the Food and Drug Administration does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a trusted third party, such as USP, ConsumerLabs, or NSF.

However, even if supplements are third-party tested, that doesn’t mean that they are necessarily safe for all people or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and check in about any potential interactions with other supplements or medications.

Supplement Facts

  • Active ingredient(s): Nicotinic acid
  • Alternate name(s): B3, nicotinic acid, nicotinamide, nicotinamide riboside
  • Legal status: Available over the counter (OTC)
  • Suggested dose: 14-16 milligrams (mg)/day
  • Safety considerations: Niacin can interfere with some medications, and high doses can lead to complications
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Uses of Niacin

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or doctor. No supplement is intended to treat, cure, or prevent disease. 

In the body, niacin converts to a coenzyme (a substance that activates an enzyme) called nicotinamide adenine dinucleotide (NAD). There are more than 400 enzymes in the body that require NAD for performing functions like:

  • Creating energy
  • Maintaining healthy genes
  • Cell communication
  • Antioxidant function (protecting cells from free radicals)

In addition, some people take niacin for the benefits related to specific health conditions, including heart disease, Alzheimer's disease, high blood pressure, and diabetes. There is limited evidence to support niacin for these uses.

Heart Disease

Niacin is known to decrease low-density lipoprotein (LDL, aka "bad cholesterol"), triglycerides (fat found in the blood), and lipoprotein (particles that carry cholesterol in the blood). Therefore, some studies have evaluated its use in treating and preventing heart disease.

A 2017 review of randomized controlled trials published in Cochrane evaluated niacin for the prevention of cardiovascular events. The review included 23 trials with 39,195 participants with an average treatment duration of 11.5 months and a median dose of 2 grams (g) per day.

In this review, researchers found that niacin did not reduce overall, heart-related, or non‐cardiovascular mortality. In addition, it did not reduce fatal or non‐fatal myocardial infarctions (heart attacks) or strokes.

Similarly, a 2018 meta-analysis with 29,195 participants looked at the supplement's effect on preventing cardiovascular disease. Compared to control groups that received only statins (prescription medications that improve cholesterol), the groups that received 1-3 g of niacin in addition to statin had a 10% greater all-cause mortality.

The American Heart Association (AHA) and American College of Cardiology (ACC) do not recommend niacin to prevent or treat heart disease, especially for those who take statins. However, healthcare providers sometimes prescribe niacin for those who can not tolerate statins.

Alzheimer's Disease

Niacin is associated with improved cognitive ability and reduced cognitive decline. Therefore, some studies have looked at whether niacin might work to prevent Alzheimer's disease (a memory loss disease).

In a 2020 study published in Alzheimer's and Dementia, researchers looked at whether niacin had therapeutic potential in Alzheimer's disease. In the study, mice received 100 mg of niacin per kilogram of body weight for 30 days. After therapy, researchers analyzed the mice's brains and found that niacin had protective effects on brain cells.

Since researchers did this study on animals, it is unknown whether they could replicate these results in humans. Therefore, these results warrant further research.

A 2022 study published in Science Translational Medicine evaluated whether niacin could impact Alzheimer's disease progression. Researchers looked at how niacin affected diseased mouse brains in the study. Compared to a control group, the mice who received niacin had fewer plaques and improved cognition after therapy.

Again, scientists did this research on animals, and therefore, it is uncertain whether these results apply to humans.

Blood Pressure

Niacin's role in energy production and antioxidant/anti-inflammatory properties has prompted some researchers to evaluate whether it may help prevent hypertension (high blood pressure).

A 2021 study published in JAMA looked at dietary niacin and new-onset hypertension in Chinese adults. The nationwide cohort study included data on 12, 243 Chinese adults. Researchers measured participants' recalled dietary niacin intake over three consecutive 24-hour periods.

Participants' mean intake level was 14.8 mg per day (mg/d). At the median six-year follow-up, 4,306 participants had developed hypertension. Researchers found that in those who consumed less than 15.6 mg/d, for every 1 mg/d increase in dietary niacin, there was a 2% reduction in new-onset hypertension. However, in those with intakes greater than 15.6 mg/d, there was a 3% increase in new-onset hypertension.

These results produced a J-shaped association (one that falls then steeply rises). The turning point was 15.6 mg/d, with the lowest risk between 14.3 to 16.7 mg/d.

Diabetes

Niacin is known to reduce LDL cholesterol and triglycerides. Since those with diabetes tend to have high fat levels in their blood, researchers have looked at whether niacin could affect type 2 diabetes.

A 2014 study in Clinical Nutrition evaluated the effect of niacin on lipids and glucose (blood sugar) in people with type 2 diabetes. The meta-analysis found that niacin significantly improved lipid abnormalities. However, it also significantly increased glucose levels.

A 2020 study published in Medicine looked at the effectiveness of niacin supplementation on people with type 2 diabetes. The meta-analysis of randomized controlled trials with 2,110 participants found a reduction in bad cholesterol levels. However, it found no significant effects on plasma glucose levels.

There is currently insufficient evidence to support niacin for diabetes treatment. It may, in fact, increase the risk of developing diabetes due to its potential to increase glucose levels.

Other

In addition to the potential health benefits listed above, some people use niacin to manage migraines, skin health, and inflammatory bowel disease (IBD).

Niacin Deficiency

Some people may develop a niacin deficiency when intakes are lower over time than recommended levels, they have a specific risk factor for lower than normal levels, or there is a particular reason they are unable to digest or absorb niacin.

What Causes Niacin Deficiency?

Niacin deficiency occurs when you do not get adequate amounts from food sources. It can also happen when niacin can't convert optimally in the body, usually when you get inadequate nutrients overall.

The U.S. Department of Health and Human Services recommends:

  • 4 mg per day for infants through 11 months
  • 6 mg per day for toddlers through 3 years
  • 8 mg per day for children age 4-8
  • 12 mg per day for children age 9-13
  • 14 mg per day for females age 14-adult
  • 16 mg per day for males age 14-adult

Risk factors for niacin deficiency include:

  • Malnutrition
  • Iron deficiency
  • Other B-vitamin deficiency
  • Hartnup disease, which inhibits the absorption of the amino acid tryptophan
  • Poverty
  • Carcinoid syndrome (caused by tumors in the digestive tract)

How Do I Know If I Have a Niacin Deficiency?

You may not know if you are deficient in niacin unless your deficiency is severe. Severe niacin deficiency can lead to pellagra, a health condition that results in gastrointestinal, skin, and memory-related symptoms. Pellagra is uncommon in industrialized nations.

Pellagra symptoms include:

The memory-related symptoms can be severe and lead to aggression, paranoia, hallucinations, and even suicide. Pellagra can be fatal if untreated.

What Are the Side Effects of Niacin?

Your healthcare provider may recommend you take niacin for a health condition or deficiency. However, consuming a supplement like niacin may have potential side effects. These side effects may be common or severe. 

Common Side Effects

The most common niacin supplement side effect is skin flushing. Extended-release formulas can help with this symptom. Skin flushing looks like redness on your face, arms, and chest. You might also notice warmth, tingling, or itching with this symptom.

In addition to flushing, other symptoms may include:

  • Headache
  • Dizziness
  • Rash
  • Decrease in blood pressure

The side effects of nicotinic acid can be unpleasant. However, they do tend to subside after a couple of weeks. In the meantime, there are ways to lessen them, including:

  • Taking with food
  • Avoiding alcohol
  • Dividing the dose between multiple meals
  • For those on aspirin therapy, taking the aspirin dose half an hour before niacin

Severe Side Effects

Severe side effects are most frequently associated with high doses of niacin (more than 1 gram per day). These side effects include:

  • Hypotension (low blood pressure)
  • Fatigue
  • High blood sugar
  • Nausea
  • Heartburn
  • Abdominal pain
  • Vision changes
  • Liver damage

If you experience any of these side effects, seek medical attention immediately.

Precautions

Niacin can interact with certain medications, including those used to treat tuberculosis and diabetes. In addition, research suggests it may be risky to take with statins. So, if you take medications, be sure to discuss niacin supplementation with a healthcare provider first.

It is essential to carefully read the ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. In addition, please review the supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

Dosage: How Much Niacin Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

Most healthy individuals obtain enough niacin through their diet, so additional supplementation is not usually needed. Most research is based on deficiencies.

Some supplements contain as much as 500 mg per serving, which is higher than the recommended daily allowance for niacin. Therefore, it's essential to discuss supplementation with a healthcare provider. They can help you determine if niacin supplements make sense in your situation and can help you find the right formula and dose.

What Happens If I Take Too Much Niacin?

To avoid toxicity, be aware of the appropriate dosage and keep the tolerable upper limit in mind. The upper limit is the maximum daily amount that's considered safe and unlikely to cause adverse effects. If you consume more than this amount or more than what is recommended by your healthcare provider, you may experience the severe side effects listed above.

For niacin, toxicity has been noted in dosages over 1 gram. If you exceed these levels, you may want to seek medical advice or go to the emergency room.

Upper Intake Levels

Upper intake levels for niacin are as follows:

  • 10 mg for children 1-3 years
  • 15 mg for children 4-8 years
  • 20 mg for children 9-13 years
  • 30 mg for children 14-18 years
  • 35 mg for adults

How to Store Niacin

Store niacin in a cool, dry place. Keep niacin away from direct sunlight. Discard after one year or as indicated on the packaging.

Frequently Asked Questions

  • Can niacin lower cholesterol?

    In larger prescription doses, niacin may lower LDL ("bad") cholesterol and triglycerides. It also helps to raise HDL ("good") cholesterol.

  • Is niacin an alternative to statins?

    Niacin is not a replacement for standard medical care. The American Heart Association (AHA) and American College of Cardiology (ACC) do not recommend niacin to prevent or treat heart disease. If you take statins, it is especially important not to take niacin because some studies have found it increases mortality risk. However, if you can't take statins, a healthcare provider might prescribe niacin as an alternative.

Sources of Niacin and What To Look For

Niacin is widely available in food. Most people get enough niacin from food. However, it is also available in supplement form.

Food Sources of Niacin

Niacin is available in animal-based foods, plant-based foods, and grains. Good food sources of niacin include:

  • Meat, like beef, chicken, and turkey
  • Fish, like salmon and tuna
  • Milk and yogurt
  • Eggs
  • Vegetables, like potatoes, pumpkins, broccoli, tomatoes, spinach, and onions
  • Fruits, like bananas, raisins, and apples
  • Legumes, like edamame, tofu, and lentils
  • Fortified cereal
  • Grains, like rice, whole-grain bread, and bulgar

If a healthcare provider says you need more vitamin B3, you may need to take a supplement. Niacin supplements are available in several different forms. Each form can affect your body differently.

Immediate-Release Nicotinic Acid Supplements

Immediate-release (IR) nicotinic acid is also known as "fast-release." When you take this type, the entire dose enters your bloodstream as soon as you swallow it.

For this reason, IR nicotinic acid is more likely to cause side effects than other forms.

Some bottles may not say if they contain an "immediate-release" or a "sustained-release" product. If the label doesn't say, it's usually an IR product.

Extended-Release Nicotinic Acid Supplements

Extended-release (ER) nicotinic acid is available by prescription.

ER nicotinic acid is released into the body more slowly than the IR type. The ER form may cause side effects, and if it does, they are likely to be less severe than those associated with the IR form.

The brand names are:

  • Niaspan
  • Niacor

There is also a generic version. A controlled-release version called Slo-Niacin is sold OTC. This brand may be less expensive.

Sustained-Release Nicotinic Acid Supplements

Sustained-release (SR) nicotinic acid is also known as "timed-release." This form releases nicotinic acid over a period of time rather than all at once.

The SR form may cause side effects, and if it does, they're likely to be milder than those brought on by the IR form.

The SR form will take longer to clear the body than the IR or the ER form. For this reason, SR nicotinic acid comes with the risk of vitamin toxicity, which can lead to liver damage.

Don't take SR niacin if you have a liver disease such as cirrhosis or chronic hepatitis B or C infection. Instead, choose an IR or ER version.

Summary

Niacin is an essential form of vitamin B that your body needs for proper cell function. Some people take niacin for health reasons, including heart disease and Alzheimer's disease. However, research is limited, and insufficient evidence supports it for these uses.

Most people get enough niacin from the food they eat. In some cases, though, healthcare providers may prescribe niacin supplements to treat niacin deficiency. 

Niacin supplement side effects include flushing, headache, dizziness, and low blood pressure. If you have side effects, you may want to try a different formula or start with a smaller dose.

Don't take high doses of niacin. High doses can cause serious side effects. Ask your doctor before you start taking niacin or any other supplement.

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