Niacin (Vitamin B3) Uses, Benefits, Dosages, Side Effects & Interactions

Niacin is commonly called vitamin B3. It is also known as nicotinic acid.

Niacin supplements are taken by bodybuilders as pre-workout supplements, to promote circulatory function, skin health, cognitive function and energy metabolism.

Like the other eight members of the B-complex family of vitamins, vitamin B3 is important for helping the body convert carbohydrates from the diet into usable energy.

B vitamins also help to break down fats and proteins from foods. B vitamins are also important for the maintenance and function of the nervous system, liver, eyes, skin, and hair.

Niacin is used in the adrenal glands and some other body parts to manufacture stress-related and sex hormones. Vitamin B3 also helps to enhance circulation and reduce redness and swelling (inflammation). [1, 2]

In research, niacin has been seen to have blood lipid lowering effects and may support normal cholesterol levels. Prescription niacin products exist for treating abnormal blood lipid levels.

This article explores what health authorities have learned about niacin from research studies. Its definition, uses, benefits, food sources, dosages, safety, side effects, and interactions will be discussed.

Niacin

Vitamin B3 Supplement

Heart Health

Blood Lipids

Energy

How It Works:

• Helps maintain healthy cholesterol levels
• Supports proper metabolic functioning
• Promotes heart & nervous system health

Dosage:

Between 100 - 500 mg per day

Safety:

Rated Likely Safe

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What is Niacin?

Niacin’s scientific name is 3-Pyridinecarboxylic Acid. [4]

The National Cancer Institute (NCI) states that vitamin B3 is a water-soluble vitamin that the body does not store. It occurs naturally in many plants and animals, and is known to have antihyperlipidemic (blood lipid-lowering) effects. [1]

The Linus Pauling Institute (LPI) reports, “Niacin and its derivative nicotinamide are dietary precursors of nicotinamide adenine dinucleotide (NAD), which can be phosphorylated (NADP) and reduced (NADH and NADPH).” [2]

The LPI states that NAD: [2]

• Functions in oxidation-reduction (redox) reactions and non-redox reactions
• Is critical for genome stability
• Is the sole substrate for PARP enzymes involved in DNA repair

There are two other forms of niacin that induce unique biological effects in humans. They are called nicotinamide and inositol hexanicotinate. [2]

The molecular structure of different niacin forms is similar to that of nicotine, the toxic alkaloid and parasympathomimetic stimulant found in tobacco. However, these compounds are not related, and do not induce the same types of biological effects. [2]

How Does Vitamin B3 Work Inside the Body?

Niacin coenzymes NAD and NADP are important in tissue respiration, the metabolic process where cells absorb oxygen and release carbon dioxide. They are also part of the metabolism of glycogen, amino acids and proteins, lipids (fats), and purines. [1]

Vitamin B3 has a number of effects on the cardiovascular system and blood lipid levels. In medicinal doses, niacin, but not its derivative nicotinamide, has been seen to lower blood lipid levels, and reduce both the number of coronary events and total mortality rates in patients at high risk for coronary heart disease. [2]

The NCI states, “Although the exact mechanism of action by which niacin lowers cholesterol is not fully understood, it may act by inhibiting the synthesis of very low-density lipoproteins (VLDL), inhibiting the release of free fatty acids from adipose tissue, increasing lipoprotein lipase activity, and reducing the hepatic synthesis of VLDL-C and LDL-C.” [1]

There are some vitamin B3 products available that are FDA-approved prescription medications used for treating primary hyperlipidemia and mixed dyslipidemia.

Dyslipidemia refers to an abnormal amount of lipids in the blood (can be higher or lower than average). Hyperlipidemia refers to abnormally elevated levels of lipids in the blood; it is the most common form of dyslipidemia.

Research continues to explore how niacin works alone, or with lipid-lowering medications, to induce cardiovascular benefits. [2]

Our bodies can produce vitamin B3 from the amino acid tryptophan, but not very efficiently. Certain nutritional deficiencies may also negatively affect this process; further reducing tryptophan conversion. [2]

According to the NMCD, “Dietary tryptophan, which is found in protein-containing foods such as red meat, poultry, eggs, and dairy products, is also converted to niacin after ingestion. Consumption of tryptophan 60 mg equals 1 mg of niacin or one niacin equivalent (NE).” [4]

The LPLI states, “Elevated tryptophan breakdown and niacin deficiency have been reported in HIV-positive people. This population is also at high risk for cardiovascular disease, and current data show that they could benefit from niacin supplementation.” [2]

The NCI reports that several studies have suggested vitamin B3 may also act as a cancer preventive agent. However, most of the studies have been in-vitro (cultured cell) or animal-based. Clinical trials are still needed to determine if these effects are seen in humans. [2]

Uses for Niacin

PubMed Health states that niacin is an antihyperlipidemic (lowers blood lipid levels), a nutriceutical (food used for medicine), and a nutritive agent (nourishes body). [3]

Prescription-grade vitamin B3 is used by some doctors to treat high cholesterol (hypercholesterolemia), high serum triglycerides (hypertriglyceridemia), and niacin deficiency. [3]

According to PubMed Health, using niacin for lowering blood lipid levels “may help prevent the development of pancreatitis (inflammation of the pancreas) and other problems caused by high levels of cholesterol and triglycerides in the blood.” [3]

Doctors will sometimes use pharmaceutical-grade vitamin B3 to inhibit arterial narrowing and reduce heart attack risks, especially in those who have had heart attacks or hyperlipidemia in the past. [3]

The Natural Medicines Comprehensive Database (NMCD) states that some people use oral niacin supplements for: [4]

• ADHD (Attention Deficit-Hyperactivity Disorder)
• Alzheimer’s disease and age-related cognitive decline
• Anti-aging
• Cholera related diarrhea
• Detoxifying from pollutants and toxins
• Drug-induced hallucinations
• Improving orgasms
• Peripheral vascular disease
• Premenstrual headaches
• Vasculitis associated with skin lesions

Niacin is also used orally for improving circulation, digestion and exercise performance. It is also used for lowering blood pressure, preventing nuclear cataracts, and promoting CNS (central nervous system) relaxation. [4]

Vitamin B3 supplements are also used by some people for headache, vertigo, depression, motion sickness, edema, and alcohol dependence. It is also taken by mouth for vascular spasms, acne, leprosy, arthritis, hyperkinesis, and schizophrenia. [4]

Some people also used niacin orally to prevent positive outcomes on laboratory tests that screen for illicit drug residues. [4]

Niacin Health Benefits

The Natural Medicines Comprehensive Database has rated Niacin as Likely Effective for dyslipidemia and pellagra (a condition associated with niacin deficiency).

The NCMD has also rated niacin as Possibly Effective for atherosclerosis, cholera, HIV/AIDS-related dyslipidemia, and metabolic syndrome.

At this time there is insufficient clinical research available to rate vitamin B3 for any other common uses. More research is needed to determine the therapeutic efficacy of niacin for these uses.

The FDA has approved certain vitamin B3 products as prescription drugs to treat certain conditions such as dyslipidemia. Dietary supplement forms of vitamin B3 are typically much lower strength compared to prescription products and are usually not appropriate for these conditions.

Dietary supplement forms of niacin are not approved by the FDA as drugs to prevent or treat any conditions.

Effects on Cholesterol

The Mayo Clinic (MC) reports that niacin is a widely accepted treatment for high cholesterol.

According to MC, “Multiple studies show that niacin (not niacinamide) has benefits on levels of high-density cholesterol (HDL or ‘good cholesterol’), with better results than drugs such as ‘statins’ like atorvastatin (Lipitor®).” [5]

Niacin also positively affects LDL (low-density lipoprotein) cholesterol levels, but not as much as it does HDL-C. [6]

There is some evidence that this vitamin may contribute to reducing cardiovascular events in some patients according to the NCMD. Some clinical research has shown that taking Vitamin B3 alone as a treatment for lowering cholesterol may reduce the risk of heart attack in men.

According to the NCMD, “Other evidence suggests that taking niacin in combination with clofibrate for up to 5 years reduces the risk of ischemic heart disease mortality by 36% compared to control in patients who survived a myocardial infarction.” [4]

Statins are a class of drugs that are commonly used for reducing cholesterol levels. They achieve this effect by reducing the production of cholesterol by the liver. Statins and niacin have previously been used in combination as a treatment for lowering cholesterol.

However, there is some controversy over taking statins and niacin together. One older smaller study found that taking vitamin B3 in combination with simvastatin (Zocor) reduced cardiovascular events in people with low HDL levels and coronary disease.

More recent larger scales study have found that a combination of oral statins and niacin did not reduce the risk of cardiovascular events of people who were already at their target LDL levels though.

Medscape quotes the FDA saying, “Scientific evidence no longer supports the conclusion that a drug-induced reduction in triglyceride levels and/or increase in HDL-cholesterol levels in statin-treated patients results in a reduction in the risk of cardiovascular events.” [6]

The FDA has determined that the benefits of niacin and stains together no longer outweigh the risks. They have consequently withdrawn approval for the coadministration of statins and niacin.

More research is still needed in this area to determine what the best course of treatment is for different people based on various physiological factors. Speak with your doctor if you are interested in taking niacin for dyslipidemia.

While niacin has been seen to lower cholesterol levels in humans, another effect it has may actually raise levels in some situations.

Niacin is able to increase levels of homocysteine, a homologue of the amino acid cysteine. High serum levels of homocysteine may increase serum lipid levels. [6]

Notably, using this drug to reduce cholesterol levels in patients with type 2 diabetes might make it more difficult to control blood-glucose levels. [6]

The NMCD reports, “Niacin can impair glucose tolerance in a dose-dependent manner, probably by causing or aggravating insulin resistance. The effects of niacin on triglyceride synthesis may also increase hepatic output of glucose by enhancing fatty acid utilization in the liver at the expense of glucose.” [4]

All evidence considered, most research has shown that niacin can successfully lower LDL cholesterol levels in people with dyslipidemia. Prescription vitamin B3 products exist for this purpose.

In many cases the use of niacin to reduce cholesterol levels is a second-line therapy after primary treatment with other medications like statins. In some cases, vitamin B3 use is a primary treatment when the situation calls for it, such as cases where patients have mixed hyperlipidemia, or need to increase HDL levels and lower triglyceride levels. [4]

Additional Vitamin B3 Benefits

According to the Mayo Clinic, preliminary evidence from human research suggests that niacin may be beneficial for: [5]

• Acne and other dermatological conditions
• Alzheimer’s disease and dementia
• AMD (age-related macular degeneration)
• ED (erectile dysfunction)
• Headache
• Hepatitis C
• High blood phosphorus levels
• Osteoarthritis (niacinamide)
• Type 1 diabetes mellitus
• Type 2 diabetes mellitus

Further clinical trials are still needed to determine any ways that niacin can benefit these or any other health conditions though.

It is always recommended to seek professional medical advice before beginning to use dietary supplements like niacin.

Niacin Deficiency

Except for in chronic, severe alcoholics, niacin deficiency is very rare in the United States and other developed countries. [4] Deficiency is more common in places where cereal grains or corn make up a large portion of the diet.

Niacin deficiency is broken up into two categories, primary deficiency and secondary deficiency, based on the root cause.

Primary niacin deficiency can be caused by: [7]

• Defective tryptophan absorption
• Inadequate oral intake
• Long-term use of chemotherapeutic treatments
• Metabolic disorders
• Poor bioavailability from unlimited grains

Primary deficiency is often accompanied by deficiency in protein and other B-complex vitamins. Chronic diarrhea, liver cirrhosis, and alcoholism may cause secondary niacin deficiency. [7]

Pellagra is a disease caused by severe niacin deficiency. The NMCD states, “This syndrome, affecting the gastrointestinal tract, skin, and central nervous system, is characterized by dermatitis, dementia, and diarrhea.” [4]

Merck Manuals reports, “Primary niacin deficiency results from extremely inadequate intake of both niacin and tryptophan, which usually occurs in areas where maize (Indian corn) constitutes a substantial part of the diet.” [7]

Merck Manuals reports that aside from the 3 D’s (dementia, dermatitis, and diarrhea), other pellagra symptoms can include: [7]

• Abdominal distention
• Butterfly-shaped lesions on the face
• Constipation
• Glossitis (inflammation of tongue)
• Inflamed mucous membrane tissues in vagina or urethra
• Pellagrous glove (glove-like distribution of hand lesions)
• Stomatitis (mouth mucous membrane inflammation)
• Symmetric photosensitive rash

According to the Merck Manual the psychosis that results from severe pellagra can cause “memory impairment, disorientation, confusion, and confabulation; the predominant symptom may be excitement, depression, mania, delirium, or paranoia.” [7]

The most severe cases of pellagra can lead to nervous system dysfunction, and death if left untreated. [7]

Niacin deficiency and pellagra are usually diagnosed clinically, and oral dietary supplementation normally reverses symptoms. [7]

Niacin Foods

For most people, eating a diverse diet that includes the following foods will provide adequate niacin:

• Beets
• Brewer’s yeast
• Beef liver
• Beef kidney
• Fish
• Salmon
• Swordfish
• Tuna
• Sunflower seeds
• Peanuts [8]

University of Maryland Medical Center (UMM) states, “Bread and cereals are usually fortified with niacin. In addition, foods that contain tryptophan, an amino acid the body converts into niacin, include poultry, red meat, eggs, and dairy products.” [8]

Niacin Supplements

Vitamin B3 supplements are commonly labeled as niacin, niacinamide, or inositol hexaniacinate. They come in capsule and tablet forms, and in time-release and regular release varieties. [8]

The University of Maryland Medical Center states that the time-release forms may cause fewer overall side effects. However, the time-release types are also more likely to cause hepatic (liver) damage in rare cases or if overused. [8]

According to UMM, “Regardless of which form of niacin you are using, doctors recommend periodic liver function tests when using high doses (above 100 mg per day) of niacin.” [8]

The NMCD reports that there are more than 6500 different dietary supplements that contain niacin. It is recommended to look for products that are not genetically modified (non-GMO) and are certified organic and toxin-free.

Like other B-complex vitamins, this compound is destroyed by too much exposure to heat, light, or air. Buy Vitamin B3 products that come in dark-colored containers. Store your supplement in low-lit, cool spots in tightly-sealed containers.

Continued supplementation of one B vitamin can potentially throw off the balance of the other B vitamin complex compounds in the body. It is typically recommended to take a multivitamin that contains a variety of B vitamins unless otherwise instructed by your doctor.

Common Vitamin B3 Dosages

Medscape reports the following niacin RDAs (recommended daily allowances): [6]

• 14 milligrams (mg) for females 19 years and older
• 16 mg for males 19 years and older
• 17 mg while breastfeeding
• 18 mg while pregnant

Oral doses of niacin are well-absorbed in humans. A 1-gram dose seems to increase plasma levels “from 0.15 mcg/mL to 16.5 mcg/mL by 60 minutes after oral ingestion.” [4]

Peak plasma-niacin concentrations occur about 4 ½ hours after oral ingestion. NMCD states, “In humans, the bioavailability of unchanged niacin from a single 500 mg dose appears to be 1% from two slow-release formulations and 25% from a rapid-release formulation.” [4]

Niacin Side Effects and Safety

The Natural Medicines Comprehensive Database has rated niacin as Likely Safe when used orally and appropriately as a dietary supplement. [4]

During pregnancy and lactation, niacin is also rated as Likely Safe, when used in amounts that do not exceed the RDA’s for pregnant and nursing women (18 mg and 17 mg respectively). [34/a>]

However, the NMCD states, “There is insufficient reliable information available about the safety of larger oral doses of niacin, niacinamide, or topical niacinamide when used during pregnancy or lactation; avoid using.” [4]

This vitamin is generally well tolerated when taken at amounts found in food or supplements and serious side effects are rare.

One common side effect that has been reported when first taking niacin supplements or when taking higher dosages of Vitamin B3 is something known as the “niacin flush.”

The skin flushing reaction is described as a feeling of heat or itching that commonly manifests in the face or upper body after taking an oral dose of niacin.

This uncomfortable, but harmless, effect is caused by the blood vessels near the skin dilating and allowing greater blood flow. Medscape states that taking a nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen 30-60 minutes before dosing may decrease flushing symptoms [6]

PubMed states that you should contact your doctor immediately if you notice any of the following adverse reactions after taking a niacin supplement: [3]

• Chest tightness
• Dark urine or pale stools
• Itching, hives or other allergic reactions
• Loss of appetite
• Muscle pain, tenderness, or weakness
• Nausea or vomiting
• Stomach pain
• Swelling in your face or hands
• Swelling or tingling in your mouth or throat
• Trouble breathing
• Unusual bleeding or bruising
• Yellow skin or eyes

It is always recommended to speak with your doctor before beginning any new supplements to help determine if the supplement is right for your needs and to help avoid side effects.

Drug Interactions & Contraindications

Seek medical advice and use caution if taking niacin along with any of the following:

Anticoagulant/antiplatelet drugs like aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others. [4]

Anticoagulant/antiplatelet herbs and supplements including angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, horse chestnut, red clover, turmeric, and others. [4]

Antidiabetes drugs like glimepiride (Amaryl), tolbutamide (Orinase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), and many others. [4]

Antihypertensive drugs like captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDiuril), furosemide (Lasix), and many others. [4]

Herbs and supplements with antihypertensive potentials like andrographis, casein peptides, cat’s claw, coenzyme Q-10, fish oil, L-arginine, lycium, stinging nettle, theanine, and others. [4]

Bile acid sequestrants like cholestyramine, colesevelam, colestipol, colesevelam hydrochloride, colestipol hydrochloride, and others. [4]

Hepatotoxic drugs like acetaminophen (Tylenol), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), and many others. [4]

Hepatotoxic herbs and supplements like androstenedione, borage leaf, chaparral, comfrey, dehydroepiandrosterone (DHEA), germander, kava, pennyroyal oil, red yeast, and others. [4]

HMG-CoA reductase (“statin”) drugs like atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), pravastatin (Pravachol), and simvastatin (Zocor). [4]

Thyroid hormone replacement drugs like levothyroxine (Synthroid, Levoxyl). [4]

Other interactions may exist between niacin and prescription medications. It is always recommended to speak with your doctor before starting any new supplements, especially if you are taking any current medications or have a pre-existing medical condition.

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