Overview
Vitamin B3, also called niacin (nicotinic acid), is one of eight B vitamins. It has 2 other forms, niacinamide (nicotinamide) and inositol hexanicotinate, which have different effects from niacin. All B vitamins help the body convert carbohydrates into fuel (glucose), which is used to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body metabolize fats and protein. B complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly, and are needed for good brain function. All B vitamins are water-soluble, meaning that the body does not store them and must be replenished daily.
Niacin also helps the body make various sex and stress-related hormones in the adrenal glands and other parts of the body. Niacin helps improve circulation.
Symptoms of mild deficiency include indigestion, fatigue, canker sores, vomiting, and depression. Severe deficiency can cause a condition known as pellagra. Pellagra is characterized by cracked, scaly skin, dementia, and diarrhea. It is generally treated with a nutritionally balanced diet and niacin supplements. Niacin deficiency also causes burning in the mouth and a swollen, bright red tongue.
Dietary Sources
The best food sources of vitamin B3 are found in beets, brewer’s yeast, beef liver, beef kidney, fish, salmon, swordfish, tuna, sunflower seeds, and peanuts. In addition, foods that contain tryptophan, an amino acid the body coverts into niacin, include poultry, red meat, eggs, and dairy products.
Upper Limits
The Council for Responsible Nutrition recommends different upper limits depending on the form of vitamin B3 being taken.
Nicotinic Acid: 35 mg / day
Nicotinamide: 1,500 mg / day
Inositol Hexanicotinate: 4,000 mg / day
Sources
University of Maryland Medical Center
The Council for Responsible Nutrition