Vitamin B3

Vitamin B3, also known as niacin, is one of eight B vitamins that helps in converting the food we eat into energy.

Updated: April 26, 2019

Vitamin B3, also known as niacin, is one of eight B vitamins. It helps in converting the food we eat into energy. It also helps the body to use proteins and fats, and it keeps the skin, hair, and nervous system healthy. As a supplement, niacin may help lower cholesterol, ease arthritis and boost brain function because of its antioxidative, and anti-inflammatory properties. As the body excretes excess of niacin in urine, it does not store niacin. So people must consume it in food every day.
Vitamin B3 deficiency is rare as the required amount can be obtained from a healthy diet. Your body gets niacin through food but also makes small amounts from the amino acid tryptophan. Most people can get enough from their diet alone. However, a supplement can be added if you are deficient or have another condition that may benefit from higher doses. 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.

Importance of Vitamin B3:

  • It can boost levels of good HDL cholesterol and lower triglycerides. Niacin also modestly lowers bad LDL cholesterol. It's often prescribed in combination with statins for cholesterol control, such as Crestor, Lescol, or Lipitor. Niacin is only effective as a cholesterol treatment at fairly high doses. However, these doses might have risks, such as liver damage, gastrointestinal problems, or glucose intolerance. Therefore do not take this without consulting your health care provider.
  • It helps lower the risk of type 1 diabetes by protecting insulin-creating cells in your pancreas from your own body. As type 1 diabetes is an autoimmune disease, your body attacks and destroys insulin-creating cells in your pancreas.
  • 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.
  • It could also help keep the brain healthy in cases of Alzheimer's disease.
  • It helps treat brain fog and even psychiatric symptoms as your brain needs niacin as a part of the coenzymes NAD and NADP to get energy and function properly.
  • It helps reduce atherosclerosis, or hardening of the arteries in some people.
  • Niacin seems to lower the risk of a second heart attack for people who have already had one.
  • Niacin is an FDA-approved treatment for pellagra, a rare condition that develops from niacin deficiency.
  • Niacinamide is a chemical form of niacin that doesn't lower cholesterol. However, it may help treat psoriasis and reduce your risk of non-melanoma skin cancer.
  • Niacin helps protect skin cells from sun damage, when it is used orally or applied as a lotion.
  • Niacin help ease some symptoms of osteoarthritis, improving joint mobility and reducing the need for nonsteroidal anti-inflammatory drugs (NSAIDs).
  • An injection with the vitamin reduced inflammation related to arthritis.

Dietary Sources:

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.
Foods that are high in tryptophan are good sources of niacin. The body needs tryptophan to make protein, but if there is extra, it can convert it to niacin.
The following foods are good sources of vitamin B-3:

  • Beef liver: A 3-ounce portion contains 14.9 mg or 75 percent of a person's daily value (DV)
  • Grilled chicken breast: A 3-ounce portion contains 10.3 mg or 52 percent of DV
  • Turkey breast: A 3-ounce portion has 10.0 mg or 50 percent of DV
  • Sockeye salmon: A 3-ounce piece contains 8.6 mg or 43 percent of DV
  • Cooked brown rice: One cup provides 5.2 mg or 26 percent of DV
  • Enriched breakfast cereal: One serving contains 5.0 mg or 25 percent of DV
  • Dry roasted peanuts: One ounce of these nuts contains 4.2 mg or 21 percent of DV


Vitamin B3 deficiency is rare as the required amount can be obtained from a healthy diet. However, there are several factors that can lead to low levels of B3. These include:

  • having a diet low in tryptophans or a condition that reduces the body's ability to convert tryptophan to niacin, such as Hartnup disease or carcinoid syndrome
  • under-nutrition, for example, due to alcohol use disorder, anorexia, and inflammatory bowel disease
  • a low intake of vitamin B2, B6, or iron, as this can reduce the amount of tryptophan that converts to niacin

It will cause the below symptoms when you have deficiency:

  •     a pigmented rash on skin that is exposed to the sun
  •     rough appearance to the skin
  •     bright red tongue
  •     fatigue or apathy
  •     vomiting, constipation, and diarrhea
  •     circulatory problems
  •     depression
  •     headache
  •     memory loss
  •     in severe cases, hallucinations

Uses & Effectiveness:

Likely Effective for:

High cholesterol:

Niacin seems to lower cholesterol. But not niacinamide. Some niacin products are FDA-approved prescription products for treating high cholesterol. These prescription niacin products typically come in high strengths of 500 mg or higher. Dietary supplement forms of niacin usually come in strengths of 250 mg or less. Since very high doses of niacin are required for high cholesterol, dietary supplement niacin usually isn’t appropriate.

Treatment and prevention of niacin deficiency, and certain conditions related to niacin deficiency such as pellagra:

Both niacin and niacinamide are approved by the U.S. Food and Drug Administration (FDA) for these uses. Niacinamide is sometimes preferred because it doesn't cause flushing(redness, itching and tingling), a side effect of niacin treatment.

Possibly Effective for:

Hardening of the arteries (atherosclerosis):

Taking niacin by mouth along with medicines called bile acid sequestrants seems to reduce hardening of the arteries in men with this condition. It seems to work best in people with high levels of triglycerides prior to treatment. Taking niacin with cholesterol-lowering medications also seems to reduce the risk of adverse heart-related adverse events in people with a history of narrowing or hardening of the arteries. But taking niacin does not seem to reduce hardening of the arteries in patients with a condition called peripheral arterial disease (PAD).

Diarrhea from an infection called cholera:

Taking niacin by mouth seems to control the loss of fluid due to cholera.

Abnormal levels of blood fats in people with HIV/AIDS:

Taking niacin seems to improve levels of cholesterol and blood fats called triglycerides in HIV/AIDS patients with abnormal blood fat levels due to antiretroviral treatment.

Metabolic syndrome:

Taking niacin seems to increase levels of high-density lipoprotein (HDL or 'good') cholesterol and reduce levels of triglycerides in people with metabolic syndrome. Taking the niacin along with a prescription omega-3 fatty acid seems to work even better.

Insufficient Evidence for:

Alzheimer's disease:

People who consume higher amounts of niacin from food and multivitamins seem to have a lower risk of getting Alzheimer's disease than people who consume less niacin.


Taking niacin by mouth might reduce the risk of nuclear cataracts which is the most common type of cataract.

Erectile dysfunction:

Taking extended-release niacin seems to help men with erectile dysfunction maintain an erection during sexual intercourse.

Exercise performance:

Taking a supplement containing niacin and other ingredients before exercise does not improve performance during exercise in men.

High levels of phosphate in the blood (hyperphosphatemia):

High blood levels of phosphate can result from kidney dysfunction. Taking niacin by mouth can reduce blood levels of phosphate in people with end-stage kidney disease and high levels of blood phosphate.

Blockage of the vein in the eye (retinal vein occlusion):

Taking niacin might improve eyesight in people with a blockage in the retinal vein.

Sickle cell disease:

Taking niacin does not improve the levels of blood fats in people with sickle cell disease.

More evidence is needed to rate niacin for the uses in below condition:   

  •     Acne.
  •     Alcohol dependence.
  •     Attention deficit-hyperactivity disorder (ADHD).
  •     Depression.
  •     Dizziness.
  •     Drug-induced hallucinations.
  •     Migraine or premenstrual headache.
  •     Motion sickness.
  •     Schizophrenia.
  •     Other conditions.

Side Effects:

The amount of vitamin B-3 found in food does not cause side effects. However, taking high doses of vitamin B3 as a supplement can result in adverse effects.
These include:

  •     flushed or itchy skin
  •     nausea
  •     vomiting
  •     constipation
  •     headache
  •     rash
  •     dizziness

Flushing can occur when you first begin taking it. Your health care provider will probably suggest increasing the dose slowly to reduce this problem. He or she might also offer a time-release prescription formulation to control flushing. Niacin can cause upset stomach and diarrhea.
Starting with small doses of niacin and taking 325 mg of aspirin before each dose of niacin will help reduce the flushing reaction. Alcohol can make the flushing reaction worse. Avoid large amounts of alcohol while taking niacin. However, all of these side effects tend to fade over time.
Children and women who are pregnant or breastfeeding should not take niacin supplements in excess unless it's recommended by a doctor.
More serious side effects can happen when doses of over 3 grams per day of niacin are taken.

Excess vitamin B3 can also:

  •     reduce glucose tolerance and insulin resistance
  •     trigger an attack in people with gout
  •     result in eye problems
  •     lead to gastrointestinal problems
  •     ulcers of the digestive tract
  •     increase the risk of liver damage
  •     lower blood pressure, leading to a loss of balance and risk of falls

A severe lack of vitamin B-3 can result in pellagra. The condition can be fatal.

Special Precautions & Warnings:

Pregnancy and breast-feeding:

Niacin is likely safe for pregnant and breast-feeding women when taken in the recommended amounts. The recommended amount of niacin for pregnant or breast-feeding women is 30 mg per day for women under 18 years of age, and 35 mg for women over 18.


Niacin might worsen allergies by causing histamine, the chemical responsible for allergic symptoms, to be released.

Heart disease/unstable angina:

Large amounts of niacin can increase the risk of irregular heartbeat.

Crohn's disease:

People with Crohn's disease might have low niacin levels and require supplementation during flare-ups.


As Niacin might increase blood sugar, people with diabetes who take niacin should check their blood sugar carefully.

Thyroid disorders:

Thyroxine is a hormone produced by the thyroid gland. Niacin might lower blood levels of thyroxine. This might worsen symptoms of certain thyroid disorders.

Kidney disease:

Niacin might accumulate in people with kidney disease which might cause harm.

Liver disease:

Niacin might increase liver damage. Don't use large amounts if you have liver disease.

Stomach or intestinal ulcers:

Niacin might make ulcers worse. Don't use large amounts if you have ulcers.

Gallbladder disease:

Niacin might make gallbladder disease worse.


Large amounts of niacin might bring on gout.

Very low blood pressure:

Niacin might lower blood pressure and worsen this condition.


Niacin might interfere with blood sugar control during and after surgery. Stop taking niacin at least 2 weeks before a scheduled surgery.

Fatty deposits around tendons (tendon xanthomas):

Niacin might increase the risk of infections in xanthomas.


Be cautious with the below combination as these can have moderate interaction:

Alcohol (ethanol) interacts with Vitamin B3:

Niacin can cause flushing and itchiness. Consuming alcohol along with niacin might make the flushing and itching worse. Consuming alcohol with niacin might increase the chance of having liver damage.

Allopurinol (Zyloprim) interacts with Vitamin B3:

Allopurinol (Zyloprim) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of allopurinol (Zyloprim).

Carbamazepine (Tegretol) interacts with Vitamin B3:

Carbamazepine (Tegretol) is broken down by the body. Niacinamide might decrease how fast the body breaks down carbamazepine (Tegretol).

Clonidine (Catapres) interacts with Vitamin B3:

Clonidine and niacin both lower blood pressure. Taking both niacin with clonidine might cause your blood pressure to become too low.

Medications for diabetes (Antidiabetes drugs) interacts with Vitamin B3:

Long-term use of niacin and niacinamide might increase blood sugar. By increasing blood sugar, niacin and niacinamide might decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed. Glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), metformin (Glucophage), nateglinide (Starlix), repaglinide (Prandin), chlorpropamide (Diabinese), glipizide (Glucotrol) and tolbutamide (Orinase) are some of the medications used for diabetes.

Medications used for lowering cholesterol (Bile acid sequestrants) interacts with Vitamin B3:

Some medication for lowering cholesterol called bile acid sequestrants can decrease how much niacin or niacinamide the body absorbs. This might reduce the effectiveness of niacin or niacinamide. Niacin or niacinamide and these medications should be taken at least 4 hours apart. Cholestyramine (Questran) and colestipol (Colestid) are some of the medications used for high cholesterol.

Medications used for lowering cholesterol (Statins) interacts with Vitamin B3:

Niacin can adversely affect the muscles. Some medications used for lowering cholesterol called statins can also affect the muscles. Taking niacin along with these medications for lowering cholesterol might increase the risk of muscle problems.
Rosuvastatin (Crestor), atorvastatin (Lipitor), lovastatin (Mevacor), pravastatin (Pravachol), and simvastatin (Zocor) are some of the medications used for high cholesterol.

Primidone (Mysoline) interacts with Vitamin B3:

Primidone (Mysoline) is broken down by the body. Niacinamide might decrease how fast the body breaks down primidone (Mysoline).

Probenecid interacts with Vitamin B3:

Probenecid is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of probenecid.

Sulfinpyrazone (Anturane) interacts with Vitamin B3:

Sulfinpyrazone (Anturane) is used to treat gout. Taking large doses of niacin might worsen gout and decrease the effectiveness of sulfinpyrazone (Anturane).
Be watchful with the below combination as these can have minor interaction:

Aspirin interacts with Vitamin B3:

Aspirin is often used with niacin to reduce the flushing caused by niacin. Taking high doses of aspirin might decrease how fast the body gets rid of niacin. This could cause there to be too much niacin in the body and possibly lead to side effects. But the low doses of aspirin most commonly used for niacin-related flushing don't seem to be a problem.

Nicotine patch (Transdermal nicotine) interacts with Vitamin B3:

Niacin can sometimes cause flushing and dizziness. The nicotine patch can also cause flushing and dizziness. Taking niacin and/or niacinamide (vitamin B3) and using a nicotine patch can increase the possibility of becoming flushed and dizzy.


The amount of niacin you need is based on the reference daily intake (RDI) and depends on your age and gender. Therapeutic doses of niacin are higher than the recommended amounts and should only be taken under medical supervision.
The following doses have been studied in scientific research and is recommended:


By Mouth:

For high cholesterol:

The effects of niacin are dose-dependent. Doses of niacin as low as 50 mg and as high as 12 grams each day have been used. However, taking 1200 to 1500 mg/day can increase HDL and decrease triglycerides more effectively. Niacin is more effective on LDL when taken 2000 to 3000 mg/day. Niacin is often used with other medications for improving cholesterol levels.

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra:

300-1000 mg daily in divided doses.

For treating hardening of the arteries:

Doses of niacin have been used as high as 12 grams daily. However, a dose of about 1 to 4 grams of niacin daily, alone or along with statins or bile acid sequestrants (a cholesterol-lowering medicine), has been used for up to 6.2 years.

For reducing fluid loss caused by cholera toxin:

2 grams daily has been used.

For abnormal blood fat levels due to treatment for HIV/AIDS:

Up to 2 grams daily has been used.

For metabolic syndrome:

2 grams of niacin has been taken daily for 16 weeks. In some cases, niacin 2 grams daily, alone or at this dosage, is taken along with 4 grams of prescription omega-3 ethyl esters (Lovaza, GlaxoSmithKline Pharmaceuticals).

By IV:

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra:

60 mg of niacin has been used.

As a Shot:

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra:

60 mg of niacin has been used.


By Mouth:

For preventing and treating vitamin B3 deficiency and related conditions such as pellagra:

100-300 mg per day of niacin, given in divided doses.

The daily recommended dietary allowances (RDAs) of niacin are:

  • Infants 0-6 months, 2 mg
  • Infants 7-12 months, 4 mg
  • Children 1-3 years, 6 mg
  • Children 4-8 years, 8 mg
  • Children 9-13 years, 12 mg
  • Men 14 years and older, 16 mg
  • Women 14 years and older, 14 mg
  • Pregnant women, 18 mg
  • Lactating women, 17 mg.

The tolerable upper level (UL) for maximum daily dose of niacin is:

  • Children 1-3 years, 10 mg
  • Children 4-8 years, 15 mg
  • Children 9-13 years, 20 mg
  • Adults, including Pregnant and Lactating women, 14-18 years, 30 mg
  • Adults, including pregnant and breast-feeding women, older than 18 years, 35 mg.

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