Niacin (also known as vitamin B3, nicotinic acid and vitamin PP) is an organic compound composed of two structures: nicotinic acid and nicotinamide (also known as niacinamide and nicotinic acid amide) and is one of the 40 to 80 essential human nutrients. Little less than 70% of niacin required by an adult can be converted from the amino acid tryptophan. For the formation of 1 mg of niacin 60 mg of tryptophan is needed. Niacinamide can be made from niacin in the body .
Niacin and niacinamide action and uses
According to MedlinePlus  niacin and niacinamide are likely effective for treating high cholesterol and niacin deficiency and possibly effective for osteoarthritis, Alzheimer’s disease, reducing the risk of heart attack, diabetes type 1 and 2.
Aerobic exercise and niacin are frequently used strategies for reducing serum triglycerides. However, more recent trial with 1500 mg niacin per day showed no trend for improvements in total cholesterol, LDL-C, HDL-C or triglycerides.
Sources and RDA
The RDA for niacin has been set to about 14-18 mg per day for adults . Its requirements are usually linked to energy intake. So athletes with high energy intake need a proportionally higher niacin intake. Due to its high availability in plants and animals, athletes show no evidence of niacin deficiency except those on restricted weight control diet. Vitamin B3 can be found in yeast, milk, meat, fish, eggs, beans, green vegetables, and many vitamin b complex supplements .
Niacin and niacinamide are likely safe for most people when taken by mouth. 
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