Vitamin B. Polarised light micrograph of crystals of niacinamide also known as nicotinamide. Niacinamide is the active form of the water- soluble nicotinic acid which belongs to the vitamin B complex group of vitamins. Niacinamide plays an essential role in the metabolism of sugars and fats, the manufacture of sex hormones and the maintenance of healthy skin. Its main dietary sources include liver, fish, nuts and dried beans. Prolonged deficiency of this vitamin causes pellagra, the principal symptoms of which include dermatitis, diarrhoea and mental disturbances. Pellagra may be fatal in the most severe cases. Magnification: x10 at 35mm size.