A study done by Stanford University School of Medicine and Stanford Hospital&Clinics suggests that the use of a dietary supplement after Roux-en-Y gastric bypass surgery can help obese patients to more quickly lose weight and to avoid deficiency of a critical B vitamin.

In the study published in the Journal of Gastrointestinal Surgery, John Morton, MD, associate professor of surgery at the medical school, says patients who take probiotics after the gastric-bypass procedure tend to shed more pounds than those who don't take the supplements. Probiotics are the "good" bacteria found in yogurt as well as in over-the-counter dietary supplements that help in the digestion of food.

The researchers followed 44 patients on whom Morton had performed the procedure from 2006 to 2007. Patients were randomized into either a probiotic or a control group. Both groups received the same bariatric medical care and nutritional counseling, as well as the support of weight-loss study groups. Both groups also were allowed to consume yogurt, a natural source of probiotics. In addition, the probiotic group consumed one pill per day of Puritan's Pride, a probiotic supplement that is available online and in many stores. Morton has no financial ties to the company that makes the supplement.

The study showed that at three months, the probiotics group registered a 47.6 percent weight loss, compared with a 38.5 percent for the control group.

"Surprisingly, the probiotic group attained a significantly greater percent of excess weight loss than that of control group," said Morton, who wrote the paper with lead author Gavitt Woodard, a third-year medical student, and five other medical students at the Surgery Center for Outcomes Research and Evaluation in Stanford's Department of Surgery. Morton has performed more than 1,000 of these bypasses at Stanford Hospital & Clinics.

The study also found that levels of vitamin B-12 were higher in the patients taking probiotics — a significant finding because patients often are deficient in B-12 after gastric-bypass surgery. The probiotics group had B-12 levels of 1,214 picograms per milliliter at three months, compared with the control group's levels of 811 pg/mL.

Morton said he now recommends probiotic supplements to his patients, and he plans to continue to look for ways to enhance the outcomes from the procedure.

Roughly 15 million Americans are morbidly obese, and bypass surgery is becoming an increasingly common treatment for the problem. Some 150,000 Americans who have a body mass index of more than 40 — who are typically at least 100 pounds overweight — have the procedure each year.

Morton said the study was prompted by the fact that some patients have problems eating after gastric-bypass surgery. "For some reason, the food doesn't go down right," he said. When no anatomical reasons could be found for blockages, he hypothesized that a build-up of bacteria in the intestine — bacterial overgrowth — might be the culprit.

"Bacterial overgrowth can be bad in that it changes your motility, how you empty," Morton said. "A lot of people aren't aware that we all carry about a lot of bacteria in our intestines and that they're extremely helpful in aiding digestion. And I thought, 'Well, if we give these patients probiotics, then maybe we can improve these symptoms.'

"Part of the obesity puzzle may be due to the kind of bacteria you have in your intestine," he said.

There was no outside funding for the study.