Riboflavin, pantothenic acid, biotin, niacin, and vitamin B6 are unaffected. Wakame also has high levels of sodium, calcium, iodine, thiamine and niacin. Nicotinic acid is also known as the B vitamin niacin. The B vitamins riboflavin, thiamin, niacin, and pyridoxine dissolve into cooking water at differing rates. Later research branched out into nutrients besides niacin and vitamin C, including essential fatty acids. In the 1930s, some flour began to be enriched with iron, niacin, thiamine and riboflavin. Treatment is with either niacin or nicotinamide supplementation. Both niacin and niacinamide are rapidly absorbed from the stomach and small intestine. Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B). The pyridine ring is part of two B vitamins&colon; niacin and pyridoxine. Some conditions can prevent the absorption of dietary niacin or tryptophan and lead to pellagra. Primary pellagra is due to a diet that does not contain enough niacin and tryptophan. Nicotinamide is the preferred treatment for pellagra, caused by niacin deficiency. Some vitamins are toxic in high doses, including niacin (B), cholecalciferol (D) and tocopherol (E). Hartnup disease is a hereditary nutritional disorder resulting in niacin deficiency.