QS Study

Fat Digestion and Fat Absorption

Digestion of Fat

Criteria for dietary fat = Neutral fat (triglyceride). Lipase present in the stomach is unable to hydrolyze fats owing to the high acidity of the gastric contents. The product of carbohydrate digestion is glucose. The excess glucose converted into glycogen. And the remaining glucose stored as fat for future energy needs.

Stages of digestion

  • In the Mouth: Digestion does not occur due to an absence of enzymes.
  • In the Stomach: Here gastric lipase is less important. Lingual lipase secreted by Ebner’s gland of the tongue digests 30% of dietary triglycerides.
  • In the duodenum: Actual digestion of fat occurs in the upper small intestine by pancreatic lipase with the help of bile salt and lecithin. At first bile salts emulsify the fat globules and then Lipase acts on them to split into free fatty acids and 2-monoglycerides.

Fig: Fat Digestion and Fat Absorption

Absorption of Fat

Fat is absorbed in the form of fatty acid, glycerol, 2-monoglyceride, 1-monoglyceride, and Cholesterol. FA Containing less than 10-12 carbon atoms pass from the mucosal cells directly into the portal blood. Foodstuffs naturally also contain phospholipids, sterols like cholesterol and many minor lipids, including fat-soluble vitamins. Finally, small intestinal contents contain lipids from sloughed epithelial cells and considerable cholesterol delivered in bile.

Absorption of Fat containing more than 10-12 carbon atoms is re-esterified to triglycerides in the mucosal cells.