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 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 the body. Both forms are found in foods as well as supplements.
- Nicotinic acid: As a supplement, nicotinic acid is the form of niacin that's used to treat high cholesterol and heart disease (1).
- Niacinamide or nicotinamide: Unlike nicotinic acid, niacinamide doesn't lower cholesterol. However, it can help treat type 1 diabetes, some skin conditions and schizophrenia (2).
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 it from the amino acid tryptophan.
Bottom Line: Niacin is one of eight water-soluble B vitamins. It's also known as nicotinic acid, niacinamide and nicotinamide.
As with all of the B vitamins, niacin helps convert food into energy by helping enzymes do their job.
Specifically, niacin is a major component of NAD and NADP, two coenzymes that are involved in cellular metabolism.
You can get a sense of what a nutrient does by looking at what happens when you're deficient.
These are some of the symptoms of niacin deficiency:
- Memory loss and mental confusion
- Skin problems
That being said, deficiency is very rare in most Western countries.
Severe niacin deficiency, or pellagra, mostly occurs in third world countries, where diets are not varied.
Bottom Line: Niacin is a vitamin that makes up two major cofactors, which are compounds that help enzymes work.
Therapeutic doses of niacin are higher than the recommended amounts and should only be taken under medical supervision.
Here are the recommended dietary allowances (RDAs) for niacin (4):
- 0–6 months: 2 mg/day*
- 7–12 months: 4 mg/day*
*Adequate Intake (AI)
- 1–3 years: 6 mg/day
- 4–8 years: 8 mg/day
- 9–13 years: 12 mg/day
Adolescents and Adults
- Boys and men, 14 years and older: 16 mg/day
- Girls and women, 14 years and older: 14 mg/day
- Pregnant women: 18 mg/day
- Breastfeeding women: 17 mg/day
Bottom Line: 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 (6).
However, niacin is not the primary treatment for high cholesterol due to its possible side effects (9).
Rather, it's primarily used as a cholesterol-lowering treatment for people who can't tolerate statins (10).
2. Increases HDL Cholesterol
In addition to lowering LDL cholesterol, niacin also raises "good" HDL cholesterol.
It does this by helping to stop the breakdown of apolipoprotein A1, a protein that helps make HDL (11).
3. Lowers Triglycerides
Niacin's third benefit for blood fats is that it can lower triglycerides by 20–50% (7).
It does this by stopping the action of an enzyme that's involved in triglyceride synthesis (1).
Consequently, this lowers the production of low-density lipoprotein (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 is one way it can help prevent heart disease.
But newer research also suggests another mechanism by which it benefits your heart.
It can help reduce oxidative stress and inflammation, both of which are involved in atherosclerosis, the hardening of the arteries (1).
Some research has suggested niacin therapy, either alone or in combination with statins, could help lower the risk of health problems related to heart disease (12).
However, the research is mixed.
A recent review concluded that niacin therapy doesn't significantly help reduce the risk of heart attack, stroke or death from heart disease among people with heart disease or those who are at a high risk (10).
5. May Help Treat Type 1 Diabetes
Type 1 diabetes is an autoimmune disease in which the body attacks and destroys insulin-creating cells in the pancreas.
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 (14).
On the other hand, it has the potential to increase blood sugar levels.
As a result, people with diabetes who take niacin to treat high cholesterol levels also need to monitor their blood sugar levels carefully (14).
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 have been associated with niacin deficiency (15).
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 (16).
7. Improves Skin Function
Niacin helps protect skin cells from sun damage, whether it's used orally or applied to the skin in lotions (19).
And recent research suggests it may help prevent some types of skin cancer (20).
A 2015 study found that taking 500 mg of nicotinamide (a form of niacin) twice daily reduced rates of non-melanoma skin cancer among people at a high risk of skin cancer (20).
8. May Reduce Symptoms of Arthritis
One preliminary study showed that niacin helped ease some of the symptoms of osteoarthritis, improving joint mobility and reducing the need for NSAIDs (21).
Another study in lab rats found that an injection with the vitamin reduced inflammation related to arthritis (22).
Although this is promising, more research is needed in this area.
9. Treats Pellagra
Thus, taking a niacin supplement is the main treatment for pellagra.
Niacin deficiency is rare in industrialized countries. However, it may occur along with other diseases, such as alcoholism, anorexia or Hartnup disease.
Bottom Line: Niacin can help treat many conditions. Most notably, it helps raise HDL levels, while lowering LDL and triglycerides.
Niacin is found in a variety of foods, especially meat, poultry, fish, bread and cereal.
Some energy drinks are also loaded with B vitamins, sometimes in very high doses.
Here is how much niacin you get from a serving of each of the following foods:
- Chicken breast: 59% of the RDI (24)
- Light tuna, canned in oil: 53% of the RDI (25)
- Beef: 33% of the RDI (26)
- Smoked salmon: 32% of the RDI (27)
- Bran flakes: 25% of the RDI (28)
- Peanuts: 19% of the RDI (29)
- Lentils: 10% of the RDI (30)
- Whole wheat bread, 1 slice: 9% of the RDI (31)
Bottom Line: Many foods deliver niacin, including fish, poultry, meat, legumes and grains.
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 physician may recommend a supplement.
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. Often, therapeutic doses are measured in grams, not milligrams.
Since large amounts have many possible side effects, it's important that you tell your physician if you are taking niacin as part of any supplement.
Bottom Line: Niacin supplements may be recommended for certain conditions. However, they can have negative side effects and should be discussed with your healthcare provider.
There's no danger in consuming niacin in the amounts found in food (4).
But supplemental doses can have various side effects, including nausea, vomiting and liver toxicity (4).
Below are some of the most common side effects of niacin supplements:
- Niacin flush: Possibly the most common side effect is a flush that results from the dilation of blood vessels. In addition to a flush on the face, chest and neck, people can experience a tingling, burning sensation or pain (32, 33).
- Stomach irritation and nausea: Nausea, vomiting and general stomach irritation can occur, particularly when people take slow-release nicotinic acid. It seems to be related to elevated liver enzymes (34).
- Liver damage: This is one of the dangers of taking high doses of niacin over time to treat cholesterol. It's more common with slow-release nicotinic acid, but it can also result from the immediate-release form (35, 36).
- Blood sugar control: Large doses of niacin (3–9 grams per day) have been linked to impaired blood sugar control in both short- and long-term use (37, 38).
- Eye health: One rare side effect is blurred vision, in addition to other negative effects on eye health (39).
- Gout: Niacin can increase levels of uric acid in the body, leading to gout (40).
Bottom Line: Supplemental niacin can cause several side effects, especially in large doses. The most common of these is the niacin flush, which can occur even at lower doses.
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.
However, supplemental forms are sometimes recommended to treat certain medical conditions, including high cholesterol.