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.1,2

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.