An important member of the B-vitamin family, niacin (vitamin B-3) supplements promote healthy tissues. Niacin is also helps the body convert proteins, fats, and carbohydrates into usable energy. Acting as a coenzyme in cellular reactions, it generates energy for normal cellular function. Niacin is made in the body through the amino acid tryptophan as well as through the nicotinic acid in foods such as green vegetables, meat, poultry, fish and whole grains. Because regular niacin can cause the skin to flush, Flush-Free Niacin supplements are available. Read through the reviews below if you need help deciding which niacin supplement is best for you.