Digestion, absorption, and transport of dietary fat

Digestion, absorption, and transport of dietary fat

The average daily intake of fat in a Western diet ranges between 50 and 100 g and provides between 35% and 40% of total energy. It consists mainly of TAG, which forms the principal component of visible oils and fats, and minor quantities of phospholipids and choles-terol esters (CEs). The physical properties of dietary fat, such as their hardness at room temperature (melting point) and subsequent metabolic properties once in the body, are determined by the number of double bonds in their constituent fatty acids (degree of saturation or unsaturation) and length of the fatty acid carbon chain (see Tables 6.2 and 6.3). As men-tioned, fats that are solid at room tem-perature tend to consist of long-chain saturated fats (>14 carbons, no double bonds), whereas oils consist of long-chain unsaturated fats with several double bonds. It has become conventional to refer to dietary fats as “lipids” once they have been absorbed into the body via the small intestine, although it is not incor-rect to refer to dietary fat as “dietary lipid.”