Food Chemistry and Fish in Nutrition

4.1.1.Introduction

Foods are enzymatically digested to prepare them for absorption. During digestion in the gastrointestinal tract of mammals, the three major nutrients (carbohydrates, lipids, and proteins) undergo enzymatic hydrolysis into their building block components. This is necessary for their absorption, since the cells lining the intestine are able to absorb them into the bloodstream only as relatively small molecules. Lipids must be hydrolyzed into fatty acids and glycerol.