After providing basic information on enzymes involved in cholesterol homeostasis, and on management of hypertriglyceremia and hypercholesterolemia, with the aid of cholestyramine and fibric acid, this chapter examines the effects of the ingestion of chitosan. Dietary chitosan is effective on serum cholesterol and in atherosclerosis in normal and diabetic mice, and lends itself to the treatment of hypercholesterolemia in humans. It also exhibits antiulcer, antiarthritic, antihypertension and antiuricemic properties. The published human trials, analysed statistically, further indicate that chitosan is effective to control overweight when associated to a diet. This chapter discusses several issues raised against the use of chitosan, namely, depletion of zinc and liposoluble vitamins, as well as advantages such as enhanced absorption of nutrients and competitive inhibition of lipases. It also directs attention to the unexplored areas of fungal and algal chitosans, and the use of chitins instead of chitosans.