Which nutritional deficiencies are commonly associated with gastric bypass surgery?

Which nutritional deficiencies are commonly associated with gastric bypass surgery?

• A. Vitamin C and D only
• B. Iron only
• C. Thiamine, B12, Vitamin A, Iron, and Zinc
• D. Calcium and Vitamin K only

Answer: (C)

Gastric bypass changes how and where nutrients are absorbed, so deficiencies commonly arise from malabsorption and reduced gastric function. The altered anatomy bypasses the stomach and proximal small intestine, where many nutrients rely on specific conditions or sites to be absorbed. Thiamine deficiency can develop early after surgery because intake may be poor and vomiting is common, and stores can be depleted within weeks. B12 deficiency can occur later because production of intrinsic factor and ample gastric acid is reduced, impairing B12 absorption despite overall intake. Fat-soluble vitamins, especially vitamin A, can become low due to fat malabsorption that may accompany the altered flow through the gut. Iron absorption is mainly in the duodenum and proximal jejunum, which are bypassed, increasing the risk of iron-deficiency anemia. Zinc, absorbed in the proximal small intestine, can also become deficient for the same malabsorptive reasons. Because of these absorption changes, a combination of thiamine, B12, vitamin A, iron, and zinc deficiencies is a commonly seen pattern after gastric bypass, underscoring the need for lifelong monitoring and appropriate supplementation.

Gastric bypass changes how and where nutrients are absorbed, so deficiencies commonly arise from malabsorption and reduced gastric function. The altered anatomy bypasses the stomach and proximal small intestine, where many nutrients rely on specific conditions or sites to be absorbed.

Thiamine deficiency can develop early after surgery because intake may be poor and vomiting is common, and stores can be depleted within weeks. B12 deficiency can occur later because production of intrinsic factor and ample gastric acid is reduced, impairing B12 absorption despite overall intake. Fat-soluble vitamins, especially vitamin A, can become low due to fat malabsorption that may accompany the altered flow through the gut. Iron absorption is mainly in the duodenum and proximal jejunum, which are bypassed, increasing the risk of iron-deficiency anemia. Zinc, absorbed in the proximal small intestine, can also become deficient for the same malabsorptive reasons.

Because of these absorption changes, a combination of thiamine, B12, vitamin A, iron, and zinc deficiencies is a commonly seen pattern after gastric bypass, underscoring the need for lifelong monitoring and appropriate supplementation.