B-Complex is the term used to group a whole bunch of related vitamins together, including Vitamin B1 (Thiamine), Vitamin B2 (Riboflavin), Vitamin B3 (Niacin), Vitamin B5 (Pantothenic Acid), Vitamin B6 (Pyridoxine), Biotin, Folic Acid and Vitamin B12 (Cobalamins). They are similar to Vitamin C in that the body doesn't produce nor store them.
Each vitamin has its own set of benefits. Read this article about B-Complex at How Stuff Works if you'd like to know the specifics of each one. Basically, the group is essential for the breakdown of carbohydrates into glucose, the breakdown of fats and proteins (which aids the normal functioning of the nervous system), muscle tone in the stomach and intestinal tract, skin, hair, eyes, mouth and liver.
Each vitamin has its own set of benefits. Read this article about B-Complex at How Stuff Works if you'd like to know the specifics of each one. Basically, the group is essential for the breakdown of carbohydrates into glucose, the breakdown of fats and proteins (which aids the normal functioning of the nervous system), muscle tone in the stomach and intestinal tract, skin, hair, eyes, mouth and liver.