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 explains everything you need to know about niacin.

Niacin BenefitsShare on Pinterest

Niacin is one of the eight B vitamins, and it's also called vitamin B3.

There are two main chemical forms and each has different effects on your body. Both forms are found in foods as well as supplements.

  • Nicotinic acid: As a supplement, nicotinic acid is a form of niacin used to reduce cholesterol levels and lower your risk of heart disease (1).
  • Niacinamide or nicotinamide: Unlike nicotinic acid, niacinamide doesn't lower cholesterol. However, it may help treat psoriasis and reduce your risk of non-melanoma skin cancer (2, 3).

Niacin is water-soluble, so your body doesn't store it. This also means that your body can excrete excess amounts of the vitamin if it's not needed.

Your body gets niacin through food but also makes small amounts from the amino acid tryptophan.

Summary Niacin is one of eight water-soluble B vitamins. It's also known as nicotinic acid, niacinamide and nicotinamide.

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 (4).

Deficiency

These are some of the symptoms of niacin deficiency (5):

  • Memory loss and mental confusion
  • Fatigue
  • Depression
  • Headache
  • Diarrhea
  • Skin problems

That said, deficiency is very rare in most Western countries.

Severe niacin deficiency, or pellagra, mostly occurs in developing countries, where diets are not as varied.

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, dementia and diarrhea.

How much niacin you need is based on the reference daily intake (RDI) and depends on your age and gender (6, 7).

Therapeutic doses of niacin are higher than the recommended amounts and should only be taken under medical supervision.

Here is the RDI for niacin (6):

Infants

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

*These figures represent the Adequate Intake (AI), which is similar to RDI but based on weaker scientific evidence.

Children

  • 1–3 years: 6 mg/day
  • 4–8 years: 8 mg/day
  • 9–13 years: 12 mg/day
  • Men 14 years and older: 16 mg/day
  • Women 14 years and older: 14 mg/day
  • Pregnant women: 18 mg/day
  • Breastfeeding women: 17 mg/day

Adolescents and adults

Summary The recommended amount of niacin depends on your age and gender. Men need 16 mg per day, while most women need 14 mg per day.

1. Lowers LDL Cholesterol

Niacin has been used since the 1950s to treat high cholesterol (8).

In fact, it can lower levels of “bad” LDL cholesterol by 5–20% (9, 10).

However, niacin is not the primary treatment for high cholesterol due to its possible side effects (11).

Rather, it's primarily used as a cholesterol-lowering treatment for people who can't tolerate statins (12).

2. Increases HDL Cholesterol

In addition to lowering “bad” LDL cholesterol, niacin also raises “good” HDL cholesterol.

Studies show that niacin raises HDL levels by 15–35% (9).

3. Lowers Triglycerides

Niacin can also lower triglycerides by 20–50% (9).

It does this by stopping the action of an enzyme that's involved in triglyceride synthesis (1).

Consequently, this lowers the production of both LDL and very low-density lipoprotein (VLDL).

Therapeutic doses are needed to achieve these effects on cholesterol and triglyceride levels (1).

4. May Help Prevent Heart Disease

Niacin's effect on cholesterol may help prevent heart disease — but newer research suggests an additional mechanism by which it benefits your heart.

It can help reduce oxidative stress and inflammation, both of which are involved in atherosclerosis, or the hardening of your arteries (1).

Some research indicates that niacin therapy — either alone or in combination with statins — could help lower the risk of health problems related to heart disease (13).

However, results are mixed.

A recent review concluded that niacin therapy doesn't significantly help reduce the risk of heart attack, stroke or death from heart disease in people with heart disease or those at a high risk (12).

5. 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 at-risk children (2, 14).

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

On the one hand, it can help lower the high cholesterol levels that are often seen in people with type 2 diabetes (15).

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 (16).

6. 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 (16).

Some types of schizophrenia can be treated with niacin, as it helps undo the damage to brain cells that occurs as a result of deficiency (17).

Preliminary research shows that it could also help keep the brain healthy in cases of Alzheimer's disease. However, results are mixed (18, 19).

7. Improves Skin Function

Niacin helps protect skin cells from sun damage, whether it's used orally or applied as a lotion (20).

Recent research suggests it may help prevent some types of skin cancer as well (21).

One study found that taking 500 mg of nicotinamide — a form of niacin — twice daily reduced rates of non-melanoma skin cancer among high-risk individuals (22).

8. May Reduce Symptoms of Arthritis

In one preliminary study, niacin helped ease some symptoms of osteoarthritis, improving joint mobility and reducing the need for nonsteroidal anti-inflammatory drugs (NSAIDs) (23).

Another study in lab rats found that an injection with the vitamin reduced inflammation related to arthritis (24).

Although this is promising, more research is needed.

9. Treats Pellagra

Severe niacin deficiency causes a condition called pellagra (6, 25).

Thus, taking a niacin supplement is the main treatment for pellagra.

Niacin deficiency is rare in industrialized countries. However, it may occur alongside other diseases, such as alcoholism, anorexia or Hartnup disease.

Summary Niacin can help treat many conditions. Most notably, it helps raise “good” HDL cholesterol levels while lowering “bad” LDL cholesterol and triglycerides.

Niacin is found in a variety of foods, especially meat, poultry, fish, nuts and legumes.

Some energy drinks are also loaded with B vitamins, sometimes in very high doses.

Here is how much niacin you get from one serving of each of the following foods (26, 27, 28, 29, 30, 31):

  • Chicken breast: 59% of the RDI
  • Light tuna, canned in oil: 53% of the RDI
  • Beef: 33% of the RDI
  • Smoked salmon: 32% of the RDI
  • Peanuts: 19% of the RDI
  • Lentils: 10% of the RDI
Summary Many foods deliver niacin, including fish, poultry, meat, nuts and legumes.

There's no danger in consuming niacin in the amounts found in food (6).

However, supplemental doses can have various side effects, including nausea, vomiting and liver toxicity (6).

Below are some of the most common side effects of niacin supplements:

  • Niacin flush: Nicotinic acid supplements may cause a flush on the face, chest or neck that results from blood vessel dilation. You may also experience a tingling, burning sensation or pain (32, 33).
  • Stomach irritation and nausea: Nausea, vomiting and stomach irritation can occur, particularly when people take slow-release nicotinic acid. It seems to be related to elevated liver enzymes (34).
  • Liver damage: Long-term niacin treatment for cholesterol may cause liver damage. It's more common with slow-release nicotinic acid but can also result from the immediate-release form (35, 36).
  • Blood sugar control: Large doses of niacin of 3–9 grams per day are linked to impaired blood sugar control in both short- and long-term use (37, 38).
  • Eye health: One rare side effect is blurred vision, as well as other negative effects on eye health (39).
  • Gout: Niacin can increase levels of uric acid in your body, leading to gout (40).
Summary Supplemental niacin can cause several side effects, especially in large doses. The most common of these is niacin flush, which can occur even at lower doses.

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. A wide selection is available on Amazon.

In particular, niacin supplements may be recommended for people with high cholesterol and heart disease risk factors but who can't 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 your doctor before taking niacin as part of any supplement.

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 your doctor first.

Healthline and our partners may receive a portion of the revenues if you make a purchase using a link above.