The B-complex group of vitamins includes vitamins B-6 and B-12, as well as thiamin, riboflavin, niacin, folate, biotin and pantothenic acid. These vitamins work together to help your body metabolize the carbohydrates, protein and fat that you eat. They also function as antioxidants, protecting you from illness and premature aging. The IOM recommends men get 1 milligram of thiamin, 12 milligrams of niacin and 1.1 milligrams of riboflavin per day and that women get .9 milligrams of thiamin, 11 milligrams of niacin and .9 milligrams of riboflavin. Men and women both need 30 micrograms of biotin, 320 micrograms of folate and 6 milligrams of pantothenic acid per day.