A Mini Gastric Bypass, also called One Anastomosis Bypass or Omega Loop Gastric Bypass, is the first step on your healthy, new path. To get and keep a healthy body, you need vitamins and minerals. After a weight loss surgery you eat less and absorb fewer nutrients. A daily multivitamin prevents vitamin and mineral deficiencies. Extra calcium and protein help maintain strong muscles and bones. We therefore recommend the following multivitamins. Fully tailored to a Mini Gastric Bypass.