Collective review
Alterations in Gastrointestinal Physiology after Roux-En-Y Gastric Bypass

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Normal nutrient absorption

Nutrients are divided into five groups: protein, carbohydrate, fat, vitamins, and minerals. Normal homeostasis and weight maintenance depends on the digestion and absorption of each of these nutrients. Conversely, altered pathways of absorption result in weight loss and potentially substantial deficiencies with devastating consequences.

Protein

In addition to a decreased dietary intake of proteins secondary to the gastric pouch, the RYGB induces protein malabsorption. Under physiologic conditions, the majority of protein is absorbed in the duodenum. After RYGB, protein never enters the duodenum. Protein absorption is limited to the distal jejunum and ileum.

Other components of the RYGB contribute to protein malabsorption. Pepsinogen, as discussed already cleaves protein into peptides. After RYGB, Sundbom and colleagues16 found a

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