Bariatric Surgery: Bad to the Bone, Part 2.

As discussed in Part 1, obesity is now a global epidemic affecting a significant and rapidly increasing number of adults, adolescents, and children. As the incidence of obesity has increased, so has the use of bariatric surgery to treat it. A growing number of recently published studies have reported that, despite calcium and vitamin D supplementation, the most frequently performed types of bariatric surgery, the Roux-en-Y gastric bypass (RYGB) and the sleeve gastrectomy (SG), cause significant, ongoing bone loss. Recent studies investigating nutrient malabsorption and changes in a wide range of hormones that are induced by bariatric surgery have indicated that calcium malabsorption is just the tip of a formidable iceberg. Part 1 reviewed the latest research findings confirming that the prevalence of obesity is, in fact, skyrocketing and that bariatric surgery causes ongoing accelerated bone loss. Part 1 also discussed the mechanisms through which the malabsorption of key nutrients induced by bariatric surgery adversely affects bone. The current article, Part 2, reviews the specific changes seen in bone metabolism after bariatric surgery and the current data on the underlying mechanisms, in addition to nutrient malabsorption, that may contribute to bariatric surgery-induced bone loss. These mechanisms include mechanical unloading, calcium malabsorption despite maintenance of vitamin D levels of ≥30 ng/mL, and changes in a number of hormones, including leptin, adiponectin, testosterone, estradiol, serotonin, ghrelin, glucagon-like peptide 1 (GLP-1), and gastric inhibitory peptide (GIP). Research discussing the use of nutritional supplements to help ameliorate bariatric surgery-induced bone loss is summarized. The adverse effects of bariatric surgery on bone must be widely recognized, and protocols must be developed to prevent early onset osteoporosis in recipients of this increasingly utilized and otherwise potentially life-saving surgery.