Bacteria found in probiotic nutritional supplements, yoghurts and an increasing number of other foods may help people lose weight according to new research.
A team of researchers from Standford University School of Medicine made the discovery by accident while researching another use for probiotic supplements.
The team were using a probiotic supplement in gastric bypass surgery patients to see if they would help combat a common complication of the procedure; an overgrowth of bacteria in the gut. Gastric bypass is used in people who are very obese in an effort to limit the amount of food they can consume.
The researchers were surprised to note that those patients given the probiotic supplement lost more weight following the surgery than those who were not.
The findings were presented last Tuesday during Digestive Disease Week 2008 by Dr. John M. Morton, during a session on the management of patients with obesity.
The study involved 44 obese patients who underwent gastric bypass surgery with half being randomly assigned to receive a probiotic supplement containing 2.4 billion lactobacilli daily and the other half received a placebo pill. The treatment lasted 6 months following the surgery.
Before the surgery and at 3 and 6 months afterwards the researchers assessed the patients' quality of life, breath hydrogen levels, vitamin B12 levels and weight. The Hydrogen Breath Test (HBT) is used to determine if there is bacterial overgrowth present in the gut since bacteria give off hydrogen when they metabolise a sugary drink the patient is given prior to testing. Vitamin B12 was tested since a substance known as intrinsic factor (IF) is required for its absorption from food and IF is produced by special cells lining the stomach.
The results showed that the probiotic group lost 70% of their excess weight compared to 66% in patients in the placebo group.
It was also found that after 6 months the patients given probiotics had lower breath hydrogen, lower fasting insulin, lipoprotein A and triglyceride levels, and higher HDL cholesterol levels compared with the placebo group, although the differences were not statistically significant.
There was, however, a significantly greater improvement in quality of life in patients taking probiotics compared with those taking a placebo.
Commenting on the surprising weight loss results Dr. Morton said: "We know that the type of bacteria that we have in our intestine does determine how many calories you actually take in. So you could easily imagine that if you changed the composition of that bacteria, you'll change how many calories you absorb."
"It may be minimal, it may be a difference of a calorie or two per 100 calories ingested but, over time, that adds up."
Earlier research carried out at Washington University had shown that the composition of intestinal bacteria differed between obese mice and lean mice. The weight difference appeared to be due to the bacteria in the obese mice being highly efficient at liberating every last bit of energy from the food the mice ate. This led to the mice absorbing more calories.
This latest research appears to suggest that the same mechanism may be at work in humans. Dr. Morton believes that in the future it may be possible to change the bacterial composition in the guts of obese patients to help them to lose weight. Much more research is required first but this study may point to another important metabolic mechanism behind variations in ability to lose weight.