Vitamin status after bariatric surgery: a randomized study of gastric bypass and duodenal switch.

Study answer

What this study found

Standard supplementation did not fully prevent procedure-specific micronutrient deficits after bariatric surgery. Compared with gastric bypass, duodenal switch showed a steeper early thiamine decline (time × procedure interaction P = 0.013; DS change over time P = 0.001; GB P = 0.010), greater falls in vitamin A (GB P = 0.003; DS P < 0.001; interaction P = 0.002), and a larger decline in 25-hydroxyvitamin D (interaction P < 0.001). Riboflavin did not change significantly, while vitamin B-6 and vitamin C increased after surgery (both P < 0.001); vitamin B-12 was stable after duodenal switch…

Study & population

Randomized trial in superobese adults aged 20-50 years with BMI 50-60 at two Scandinavian centers, assigned to laparoscopic Roux-en-Y gastric bypass or laparoscopic biliopancreatic diversion with duodenal switch.

Intervention

Postoperative supplementation started 1 week after surgery in both groups and included daily multivitamins, iron sulfate 100 mg, calcium carbonate 1000 mg, and vitamin D3 10 μg.

Key limitation

This was not a supplement-versus-control trial, so the vitamin changes are strongly confounded by the two different surgical procedures and their different weight-loss effects.

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Original abstract