Complex nutrients are digested and then absorbed into the bloodstream as

Complex nutrients are digested and then absorbed into the bloodstream as monomers.

Nutrients from food can be used in the body only when are broken down to their basic units: carbohydrates in monosaccharaides, lipids in free fatty acids, proteins in amino acids and nucleic acids in nucleotides.

Those molecules together with water and minerals from the diet, are absorbed in the small intestine. The absorbed molecules are then transported into the bloodstream and carried to different parts of the body for usage, storage or chemical transformation. Some of the macromolecules are broken down in mouth (e. g. starch), or in stomach by the enzymes.