Probiotic supplements after gastric bypass surgery may help patients lose weight faster while also avoiding vitamin B deficiency, according to a study published in the July issue of the Journal of Gastrointestinal Surgery.

The Stanford University School of Medicine study included 44 patients who had Roux-en-Y gastric bypass surgery and were randomly assigned to either a probiotics group or a control group. Both groups received the same bariatric medical care and nutritional counseling and both were allowed to consume yogurt, a natural source of probiotics. Patients in the probiotics group also took one pill per day of a probiotics supplement.

After three months, the probiotics group had a 47% weight loss, compared with about 39% in the control group. Patients in the probiotics group also had higher levels of vitamin B-12 three months after surgery than those in the control group—1214 picograms per milliliter as opposed to 811 picograms per milliliter, a significant difference since B-12 deficiency is common after gastric bypass surgery.