"Our research shows that deficiencies of calcium and vitamin D absorption occur following gastric bypass surgery," said Dr. Shonni J. Silverberg, professor of medicine at Columbia University College of Physicians & Surgeons in New York, N.Y., and coauthor of the study. "When analyzing hip bone density, we found that those who lost the most weight also lost the most bone."
In this study, researchers evaluated 23 morbidly obese men and women who underwent gastric bypass surgery. Dr. Silverberg and her colleagues measured serum calcium, vitamin D, and parathyroid hormone levels before surgery and at three, six, and twelve months after surgery. Researchers also measured bone mineral density before and after surgery using dual-energy x-ray absorptiometry (DXA). One year after weight loss surgery, patients had lost an average of 99 pounds and had significant declines in hip bone mineral density (both total hip and femoral neck measurements).
"The calcium and vitamin D deficiencies may be due to the alterations in the gastrointestinal tract that take place during these procedures," said Dr. Silverberg. "These deficiencies may be restored if the amount of calcium and vitamin D supplementation is increased appropriately."