The most effective treatment for
obesity is
bariatric surgery. However, there is increasing concern that
bariatric surgery can cause nutrient deficiencies that translate into
metabolic bone disease. Whether this is true for all surgery types is not yet clear. We therefore investigated the effects of 2 commonly applied
bariatric surgeries (
Roux-en-Y gastric bypass [RYGB] and vertical sleeve
gastrectomy) on energy and bone metabolism in rats 60 days after surgery. Both surgeries resulted in similar reductions of
body weight, body fat, and food intake.
Glucose tolerance was improved to a similar extent after both surgeries and was accompanied by increased postprandial secretion of
glucose-dependent insulinotropic peptide. Using microcomputed tomography, we found that, relative to
sham-operated rats, bone volume was significantly reduced after RYGB but not vertical sleeve
gastrectomy. RYGB rats also had markedly reduced
lipid absorption from the intestine and significantly lower serum
25-hydroxyvitamin D and
calcium levels. Importantly, dietary supplementation with
calcium and
vitamin D could not fully rescue the reduced bone volume after RYGB surgery. Both surgeries resulted in a significant increase in stomach pH, which may have worsened the malabsorption in RYGB rats. Our findings suggest that bone loss in RYGB rats is not exclusively driven by
calcium and
vitamin D malabsorption but also by additional factors that may not be rescuable by dietary supplementation. These data point toward important similarities and differences between bariatric procedures that should be considered in clinical settings as guidance for which procedure will be best for specific patient populations.