Niacin, also known as vitamin B3, is an important nutrient. In fact, every part of your body needs it to function properly.

As a supplement, niacin may help lower cholesterol, ease arthritis, and boost brain function, among other benefits.

However, it can also cause serious side effects if you take large doses.

This article reviews:

  • what niacin is
  • how it works
  • its benefits
  • how to know if you should supplement with it
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Niacin is one of the eight B vitamins, and it’s also called vitamin B3 (1).

There are two main chemical forms of niacin:

  • nicotinic acid
  • niacinamide (sometimes called nicotinamide)

Both forms are found in foods as well as supplements (1).

The key role of niacin in your body is to synthesize the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are involved in over 400 biochemical reactions in your body — mainly related to obtaining energy from the food you eat (1).

Niacin is water-soluble, so your body does not store it. This also means that your body can excrete excess amounts of the vitamin through urine if they are not needed (1).

Your body gets niacin through food, but it also makes small amounts from the amino acid tryptophan, which can be found in protein sources like turkey and other animal foods (1).

Summary

Niacin is one of eight water-soluble B vitamins. Its key role is in the formation of NAD and NADP, which help your body process components from food into usable energy.

As with all B vitamins, niacin helps convert food into energy by aiding enzymes.

Specifically, niacin is a major component of NAD and NADP, two coenzymes involved in cellular metabolism.

Furthermore, it plays a role in cell signaling and making and repairing DNA, in addition to acting as an antioxidant (2).

Deficiency

These are some of the symptoms of niacin deficiency (1):

  • skin rash or discoloration
  • bright red tongue
  • vomiting
  • constipation or diarrhea
  • depression
  • fatigue
  • headache
  • memory loss
  • loss of appetite

That said, deficiency is very rare in most Western countries. People who are malnourished — which may stem from HIV/AIDS, anorexia nervosa, liver failure, alcohol abuse, or other medical problems, or poverty — are most at risk.

Severe niacin deficiency, or pellagra, mostly occurs in developing countries, where diets are not as varied. It can be treated with niacinamide supplementation (1).

Summary

Niacin is a vitamin that acts as an antioxidant and plays a role in cell signaling and DNA repair. Deficiency is characterized by skin problems, memory loss, and digestive problems.

The Recommended Daily Allowance (RDA) for niacin depends on your age and gender. For ages 7 months and older, it is expressed as mg niacin equivalents (NE). One NE is equal to 1 mg of niacin or 60 mg of tryptophan (1).

Infants

  • 0–6 months: 2 mg/day*
  • 7–12 months: 4 mg NE/day*

*These figures represent the Adequate Intake (AI), similar to RDA, but it relies more on observation and approximations of healthy populations and less on scientific evidence (3).

Children

  • 1–3 years: 6 mg NE/day
  • 4–8 years: 8 mg NE/day
  • 9–13 years: 12 mg NE/day

Adolescents and adults

  • Men ages 14 years and older: 16 mg NE/day
  • Women ages 14 years and older: 14 mg NE/day
  • Pregnant women: 18 mg NE/day
  • Breastfeeding women: 17 mg NE/day
Summary

The recommended amount of niacin depends on your age and gender. Men need 16 mg NE per day, while women who are not pregnant or breastfeeding need 14 mg NE per day.

1. Improves blood fat levels

Niacin may help to improve your blood fat levels by:

  • increasing your HDL (good) cholesterol
  • reducing your LDL (bad) LDL cholesterol
  • reducing your triglyceride levels

This may translate to a decrease in heart disease risk, although several studies have found no link between niacin supplementation and a decrease in heart disease risk or deaths (4, 5).

It also takes high doses of niacin, typically 1,500 mg or greater, to achieve blood fat level improvements, which increases the risk of experiencing unpleasant or potentially harmful side effects (6).

For these reasons, niacin is not a primary treatment for high cholesterol. It’s primarily used to help improve blood fat levels in people who cannot tolerate statin drugs (5, 7).

2. May reduce blood pressure

One role of niacin is to release prostaglandins, or chemicals that help your blood vessels widen — improving blood flow and reducing blood pressure. For this reason, niacin may play a role in the prevention or treatment of high blood pressure (8).

In one observational study of over 12,000 adults, researchers found that each 1 mg increase in daily niacin intake was associated with a 2% decrease in high blood pressure risk — with the lowest overall high blood pressure risk seen at a daily niacin intake of 14.3 to 16.7 mg per day (8).

A high quality study also noted that single doses of 100 mg and 500 mg of niacin slightly reduced right ventricular systolic pressure (9).

However, more research is needed to confirm these effects.

3. May help treat type 1 diabetes

Type 1 diabetes is an autoimmune disease in which your body attacks and destroys insulin-creating cells in your pancreas.

There’s research to suggest that niacin could help protect those cells and possibly even lower the risk of type 1 diabetes in children who have a higher chance of developing this condition (10).

However, for people with type 2 diabetes, the role of niacin is more complicated.

On one hand, it can help lower the high cholesterol levels that are often seen in people with type 2 diabetes. On the other, it has the potential to increase blood sugar levels. As a result, people with diabetes who take niacin to treat high cholesterol also need to monitor their blood sugar carefully (11).

Fortunately, a more recent review of studies found that niacin did not have significant negative effects on blood sugar management in people with type 2 diabetes (12).

4. Boosts brain function

Your brain needs niacin — as a part of the coenzymes NAD and NADP — to get energy and function properly.

In fact, brain fog and even psychiatric symptoms are associated with niacin deficiency (1, 13).

Some types of schizophrenia can be treated with niacin, as it helps undo damage to brain cells that’s caused by a niacin deficiency (14).

Preliminary research shows that it could also help keep the brain healthy in cases of Alzheimer’s disease. However, results are mixed (15, 16).

5. Improves skin health

Niacin helps protect skin cells from sun damage, whether it’s used orally or applied as a lotion (17).

It may help prevent certain types of skin cancer as well. One high quality study in over 300 people at high risk of skin cancer found that taking 500 mg of nicotinamide twice daily reduced rates of nonmelanoma skin cancer compared to a control (18).

Summary

Niacin can help treat many conditions. It appears to exert positive effects on blood fat and blood pressure levels, and may play a role in type 1 diabetes, brain health, and skin cancer prevention. However, more research is needed.

Niacin is found in a variety of foods, especially meat, poultry, fish, nuts, and legumes. Some foods may also be fortified with niacin and other vitamins, like breakfast cereals (1).

Some energy drinks also list doses — sometimes high — of B vitamins (19).

Here are some common food sources of niacin, along with how much of the Daily Value (DV) they provide (1):

  • grilled chicken breast, 3 ounces: 64% of the DV
  • roasted turkey breast, 3 ounces: 63% of the DV
  • cooked brown rice, 1 cup: 33% of the DV
  • dry roasted peanuts, 1 ounce: 26% of the DV
  • medium baked potato: 14% of the DV
Summary

Many foods contain niacin, especially meat, nuts, and legumes. Some foods are also fortified with extra B vitamins.

There’s no danger in consuming niacin in the amounts found naturally in food (1).

However, supplemental doses can have various side effects, including nausea, vomiting, and liver toxicity (1).

Of particular note is one side effect known as niacin flush. This can occur when taking 30–50 mg or more of supplemental niacin in a single dose. It causes a reddening of the skin along with burning or itching sensations. While niacin flush in and of itself isn’t typically harmful, it may be accompanied by other unpleasant side effects like headache or low blood pressure (1).

Even higher doses may cause liver damage or other severe side effects (1).

Before starting a niacin supplement, you should speak with a trusted healthcare professional.

Summary

Supplemental niacin can cause unpleasant side effects, like niacin flush. Speak with a healthcare professional before you start taking a niacin supplement.

Everyone needs niacin, but most people can get enough from their diet alone.

However, if you are deficient or have another condition that may benefit from higher doses, your doctor may recommend a supplement.

In particular, niacin supplements may be recommended for people with high cholesterol and heart disease risk factors but cannot take statins.

Supplemental forms are prescribed in doses that are much higher than the amounts found in food.

Since large amounts have many possible side effects, consult with a healthcare professional before taking niacin as part of any supplement. Also, keep in mind that the FDA does not regulate supplements in the same way it does drugs (20).

Summary

Niacin supplements may be recommended for certain conditions. However, they can have negative side effects, so you should always discuss with your healthcare provider before taking niacin.

Niacin is one of eight B vitamins that are important for every part of your body.

Luckily, you can get all the niacin you need through your diet. Foods that provide niacin include meat, fish, and nuts.

However, supplemental forms are sometimes recommended to treat certain medical conditions, including high cholesterol.

If you think you may need to take niacin, it’s always best to consult with a healthcare professional first.