Gastric by-pass surgery in morbidly obese patients markedly decreases serum levels of vitamins A and C and iron in the peri-operative period

We studied changes in serum levels of carotene, vitamins A, C, B₁₂ and folate and iron in the immediate perioperative period after gastric by-pass surgery in nine morbidly obese patients and in six patients undergoing abdominal surgery. All parameters were measured preoperatively and 48 h postoperatively. Marked decreases occurred for vitamin A (2.04 ± 0.45 μmol/l to 0.92 ± 0.39 μmol/l, P<0.01), vitamin C (26 ± 11.2 μmol/l to 4.9 ± 4.0 μmol/l, P<0.01), iron (15 ± 5.8 μmol/l to 4 ± 2.7 μmol/l, P<0.01). A significant change also occurred for carotene (1.7 ± 0.42 μmol/l to 1.25 ± 0.48 μmol/l, P<0.05). No significant changes were seen for vitamin B₁₂ and folate. Only changes in vitamins A and C were significantly greater in the morbidly obese patients compared to the control group of six patients. These changes likely represent redistribution of vitamins rather than enhanced urinary excretion.