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Vitamin B3
What is it? Overview Usage Side Effects and Warnings

Vitamin B3 Overview

Written by FoundHealth.

Vitamin B 3 is required for the proper function of more than 50 enzymes. Without it, your body would not be able to release energy or make fats from carbohydrates. Vitamin B 3 is also used to make sex hormones and other important chemical signal molecules.

Vitamin B 3 comes in two principal forms: niacin (nicotinic acid) and niacinamide (nicotinamide). When taken in low doses for nutritional purposes, these two forms of the vitamin are essentially identical. However, each has its own particular effects when taken in high doses. Additionally, a special form of niacin called inositol hexaniacinate has shown some promise as a treatment with special properties of its own.


The official US and Canadian recommendations for daily intake of niacin are as follows:

  • Infants
  • 0-6 months: 2 mg
  • 7-12 months: 4 mg
  • Children
  • 1-3 years: 6 mg
  • 4-8 years: 8 mg
  • 9-13 years: 12 mg
  • Males
  • 14 years and older: 16 mg
  • Females
  • 14 years and older: 14 mg
  • Pregnant Women: 18 mg
  • Nursing Women: 17 mg

Because the body can make niacin from the common amino acid tryptophan, niacin deficiencies are rare in developed countries. However, the antituberculosis drug isoniazid (INH) impairs the body's ability to produce niacin from tryptophan and may create symptoms of niacin deficiency. 1 Good food sources of niacin are seeds, yeast, bran, peanuts (especially with skins), wild rice, brown rice, whole wheat, barley, almonds, and peas. Tryptophan is found in protein foods (meat, poultry, dairy products, fish). Turkey and milk are particularly excellent sources of tryptophan.

Therapeutic Dosages

When used as therapy for a specific disease, niacin, niacinamide, and inositol hexaniacinate are taken in dosages much higher than nutritional needs, about 1 to 4 g daily. Because of the risk of liver inflammation at these doses, medical supervision is essential.

Many people experience an unpleasant flushing sensation and headache when they take niacin. These symptoms can usually be reduced by gradually increasing the dosage over several weeks or by using slow-release niacin. However, slow-release niacin appears to be more likely to cause liver inflammation than other forms. Inositol hexaniacinate may also cause less flushing than plain niacin, and if you take an aspirin along with niacin, the flushing reaction will usually decrease.

What Is the Scientific Evidence for Vitamin B 3 ?

Niacin is one of the best researched of all the vitamins, and the evidence for using it to treat at least one condition—high cholesterol—is strong enough that it has become an accepted mainstream treatment.

High Cholesterol/Triglycerides

Niacin has been used since the 1950s to improve cholesterol profile. Several well-designed double-blind, placebo-controlled studies have found that niacin can reduce LDL ("bad") cholesterol by approximately 10% and triglycerides by 25% while raising HDL ("good") cholesterol by 20% to 30%. 2 3 4 5 6 Niacin also lowers levels of lipoprotein(a)—another risk factor for atherosclerosis—by about 35%. Long-term studies have shown that use of niacin can significantly reduce death rates from cardiovascular disease. 7 Niacin appears to be a safe and effective treatment for high cholesterol in people with diabetes as well, and (contrary to previous reports) does not seem to raise blood sugar levels. 8

Treating Diabetes

When a child develops diabetes, there is an interval called the honeymoon period in which the pancreas can still make some insulin and there is little to no need for injected insulin. Weak evidence suggests that niacinamide might slightly delay the onset of more severe symptoms. 9 A cocktail of niacinamide plus antioxidant vitamins and minerals has also been tried, but the results were disappointing in one study. 10 However, in another study, use of intensive insulin therapy along with niacinamide and vitamin E was more effective than insulin plus niacinamide alone in prolonging the honeymoon period. 11 A recent study suggests that niacinamide may also improve blood sugar control in type 2 (adult-onset) diabetes, but it did not use a double-blind design. 12 (For information on why this is important, see Why Does This Database Rely on Double-blind Studies? )

Intermittent Claudication

Double-blind studies involving a total of about 400 individuals have found that inositol hexaniacinate can improve walking distance for people with intermittent claudication . 13 14 15 For example, in one study, 100 individuals were given either placebo or 4 g of inositol hexaniacinate daily. 16 Over a period of 3 months, participants improved significantly in the number of steps they could take on a special device before experiencing excessive pain.


There is some evidence that niacinamide may provide some benefits for those with osteoarthritis . In a double-blind study, 72 people with arthritis were given either 3,000 mg daily of niacinamide (in 6 equal doses) or placebo for 12 weeks. 17 The results showed that treated participants experienced a 29% improvement in symptoms, whereas those given placebo worsened by 10%. However, at this dose, liver inflammation is a concern that must be taken seriously.

Raynaud's Phenomenon

According to one small double-blind study, the inositol hexaniacinate form of niacin may be helpful for Raynaud's phenomenon . 18 The dosage used was 4 g daily—once again a dosage high enough for liver inflammation to be a real possibility.


  1. DiLorenzo PA. Pellagra-like syndrome associated with isoniazid therapy. Acta Derm Venereol. 47(5):318-22.
  2. Illingworth DR, Stein EA, Mitchel YB, Dujovne CA, Frost PH, Knopp RH, Tun P, Zupkis RV, Greguski RA. Comparative effects of lovastatin and niacin in primary hypercholesterolemia. A prospective trial. Arch Intern Med. 154(14):1586-95.
  3. Guyton JR, Goldberg AC, Kreisberg RA, Sprecher DL, Superko HR, O'Connor CM. Effectiveness of once-nightly dosing of extended-release niacin alone and in combination for hypercholesterolemia. Am J Cardiol. 82(6):737-43.
  4. Vega GL, Grundy SM. Lipoprotein responses to treatment with lovastatin, gemfibrozil, and nicotinic acid in normolipidemic patients with hypoalphalipoproteinemia. Arch Intern Med. 154(1):73-82.
  5. Lal SM, Hewett JE, Petroski GF, Van Stone JC, Ross G Jr. Effects of nicotinic acid and lovastatin in renal transplant patients: a prospective, randomized, open-labeled crossover trial. Am J Kidney Dis. 25(4):616-22.
  6. Elam MB, Hunninghake DB, Davis KB, Garg R, Johnson C, Egan D, Kostis JB, Sheps DS, Brinton EA. Effect of niacin on lipid and lipoprotein levels and glycemic control in patients with diabetes and peripheral arterial disease: the ADMIT study: A randomized trial. Arterial Disease Multiple Intervention Trial. JAMA. 284(10):1263-70.
  7. Canner PL, Berge KG, Wenger NK, Stamler J, Friedman L, Prineas RJ, Friedewald W. Fifteen year mortality in Coronary Drug Project patients: long-term benefit with niacin. J Am Coll Cardiol. 8(6):1245-55.
  8. Elam MB, Hunninghake DB, Davis KB, Garg R, Johnson C, Egan D, Kostis JB, Sheps DS, Brinton EA. Effect of niacin on lipid and lipoprotein levels and glycemic control in patients with diabetes and peripheral arterial disease: the ADMIT study: A randomized trial. Arterial Disease Multiple Intervention Trial. JAMA. 284(10):1263-70.
  9. Pozzilli P, Visalli N, Signore A, Baroni MG, Buzzetti R, Cavallo MG, Boccuni ML, Fava D, Gragnoli C, Andreani D. Double blind trial of nicotinamide in recent-onset IDDM (the IMDIAB III study). Diabetologia. 38(7):848-52.
  10. Ludvigsson J, Samuelsson U, Johansson C, Stenhammar L. Treatment with antioxidants at onset of type 1 diabetes in children: a randomized, double-blind placebo-controlled study. Diabetes Metab Res Rev. 17(2):131-6.
  11. Crinò A, Schiaffini R, Manfrini S, Mesturino C, Visalli N, Beretta Anguissola G, Suraci C, Pitocco D, Spera S, Corbi S, Matteoli MC, Patera IP, Manca Bitti ML, Bizzarri C, Pozzilli P, IMDIAB group. A randomized trial of nicotinamide and vitamin E in children with recent onset type 1 diabetes (IMDIAB IX). Eur J Endocrinol. 150(5):719-24.
  12. Polo V, Saibene A, Pontiroli AE. Nicotinamide improves insulin secretion and metabolic control in lean type 2 diabetic patients with secondary failure to sulphonylureas. Acta Diabetol. 35(1):61-4.
  13. O'Hara J, Jolly PN, Nicol CG. The therapeutic efficacy of inositol nicotinate (Hexopal) in intermittent claudication: a controlled trial. Br J Clin Pract. 42(9):377-83.
  14. Kiff RS, Quick CR. Does inositol nicotinate (Hexopal) influence intermittent claudication? A controlled trial. Br J Clin Pract. 42(4):141-5.
  15. Head A. Treatment of intermittent claudication with inositol nicotinate. Practitioner. 230(1411):49-54.
  16. O'Hara J, Jolly PN, Nicol CG. The therapeutic efficacy of inositol nicotinate (Hexopal) in intermittent claudication: a controlled trial. Br J Clin Pract. 42(9):377-83.
  17. Jonas WB, Rapoza CP, Blair WF. The effect of niacinamide on osteoarthritis: a pilot study. Inflamm Res. 45(7):330-4.
  18. Sunderland GT, Belch JJ, Sturrock RD, Forbes CD, McKay AJ. A double blind randomised placebo controlled trial of hexopal in primary Raynaud's disease. Clin Rheumatol. 7(1):46-9.

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