Niacin is a vitamin also known as vitamin B3. It is essential for the human body to function properly and helps convert food into energy. Full definition
A deficiency in niacin results in Pellagra, which signs are inflammation of the skin, diarrhea, dementia, dermatitis, and hallucinations. (bodybuildingforyou.com)
It also contains a fair amount of vitamin C and other nutrients such as niacin, vitamin E, calcium and iron. (amazon.com)
While it is relatively easy to meet the body's requirements for niacin via diet alone, many people remain at least mildly deficient due to an imbalanced gut environment which impairs absorption from food and limits synthesis of B3 via beneficial gut microbes (1). (thehealthyhomeeconomist.com)