Niacin (vitamin B3) is a water-soluble B vitamin and like other B vitamins, it helps to increase energy.
Niacin acts as a coenzyme and more than 400 enzymes are involved in the various reactions and are dependent on it. [1,2]
It comes in two forms in food and supplements, being nicotinic acid and nicotinamide.
Plant-based foods provide less niacin per serving than animal-based foods.
In some grain products especially, bioavailability reduces due to the presence of certain anti-nutrients and only 30 % of niacin becomes available, hence many of the bread, cereals and flours are fortified with niacin. 
Niacin deficiency leads to a disease called pellagra that has the following symptoms –