Food sources of vitamin B3 and functions in human body

Niacin is a water-soluble vitamin, also known as vitamin B3. Niacin is the generic term for nicotinic acid (pyridine 3-carboxylic acid) and nicotinamide (nicotinic acid amide) and the coenzyme forms of the vitamin. Niacin is important for the development and function of the cells in your body.

Niacin is found naturally in many foods, and is added to some foods.
• Poultry, beef, pork, anchovies and fish
• Some types of peanuts, nuts, legumes, and grains
• Enriched and fortified foods, such as many breads and cereals
• Whole grains and whole meal wheat flour

The amino acid tryptophan contributes as much as two thirds of the niacin activity required by adults in typical diets. Important food sources of tryptophan are meat, milk and eggs. Vitamin B3 is required for cell respiration and helps in the release of energy and metabolism of carbohydrates, fats and proteins, proper circulation, maintenance of healthy skin, functioning of the nervous system and normal secretion of bile and stomach fluids.

A sufficient intake of vitamin B3 (niacin) is important as it helps the body to
• convert food into glucose, used to produce energy
• produce macromolecules, including fatty acids and cholesterol
• DNA repair and stress responses.
Food sources of vitamin B3 and functions in human body

Pellagra disease due to vitamin B3 deficiency

Pellagra results from a niacin and/or tryptophan deficient diet which produces psychosis and dementia, among other symptoms. Niacin, known as vitamin B3, is a water-soluble, vitamin of the B complex group of vitamins.
The earliest description of pellagra was that of the Spanish physician Don Gaspar Casal in 1763.Casal recorded all the clinical characteristics and ascribed the disease to the unbalanced diets, based on maize, of poor peasants in the Asturia region of Spain. The next description of the disease came from Italy in 1771 when pellagra was given its name, meaning "rough skin".

Pellagra mostly found in parts of India, China, and Africa where corn or maize as a staple food. The characteristic manifestations appear as dermatitis, diarrhea and dementia ("the three Ds") and can lead to death (the fourth D).

Causes of pellagra can be divided into primary and secondary. Primary pellagra is due to dietary deficiency. High leucine content in corn/maize prevents conversion of tryptophan to niacin, leading to deficiency of niacin. Secondary pellagra is due to defective absorption or metabolism of niacin/tryptophan.

Early neurological symptoms associated with pellagra include anxiety, depression, and fatigue; later symptoms include apathy, headache, dizziness, irritability and tremors. In early cases the manifestations are psychoneurotic; later, lesions affect the nerves. As the disease advances, patients become confused, disoriented, and delirious, then comatose and stuporous, and finally die.

Mental aberrations may pass to dementia: about 4-10 % of chronic pellagra patients developmental symptoms.

In the western world, it is almost eradicated due to fortification of flour with niacin.

Pellagra disease due to vitamin B3 deficiency