Lipid Digestion Research Paper

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GI Fluids -hydrodynamics, gastric emptying and intestinal transit time

Lipid digestion
4.3 In vivo fate of dietary lipids and NLCs
Digestion and absorption of dietary lipids as well as lipid based formulations occur throughout the gastrointestinal tract (GIT). Dietary lipids predominantly constitute of long chain triglycerides (LCT) and phospholipids in lesser amounts [4, 48]. After complete digestion, LCT is hydrolyzed into three free fatty acids (FAs) and one glycerol molecule [48].
4.3.1 Digestion
The digestion of lipids is initiated when the ingested lipids disperse as a fine emulsion in the GI fluids. This is followed by hydrolysis of the lipids by lipase enzymes which subsequently form digestion products. These digestion products
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It has been reported that gastric lipase in humans show a selectivity for hydrolysis mainly towards sn-3 position, followed by favoring sn-1 position [52]. As human gastric lipase is active in a broad pH range of 2-7 with an optimum pH range between 4.5 and 5.5, it continues to contribute to lipid digestion through the duodenum [53]. In humans, the lipid digestion resulting from the stomach is responsible for about 10-30% of the hydrolysis of dietary fat which suggests that majority of the hydrolysis of fats occurs in the intestine mediated by pancreatic lipase [48,
51].
Pancreatic lipase also known as pancreatic triacylglyceride lipase preferentially hydrolyzes triacylglycerides at 1 and 3 positions yielding 2-monoglyceride and two FAs for every triacylglyceride molecule it hydrolyzes (Figure 8) [54, 55].

Figure 8: Hydrolysis of triacylglycerols by pancreatic lipase (modified from [56])
The optimal activity of pancreatic lipase is between pH 6.5 to 8.0 [55]. Pancreatic lipase binds to the emulsion interface with the help of prior binding of colipase which is an essential cofactor for exerting pancreatic lipase action. Naturally secreted bile salts help in removing adsorbed water soluble proteins including lipase from the surface which prevents from inhibiting

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