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A team of Winnipeg scientists say they've discovered one of the secrets to weight loss: Good bacteria, like the kind found in yogurt.
In their study, the researchers -- operating out of the University of Manitoba's Richardson Centre for Functional Foods -- fed 28 healthy but overweight people personalized meals containing enough calories to maintain their current body weights.
The participants who were served meals containing probiotics, the friendly flora that reside in the stomach, lost an average of four per cent body fat.
"We're thinking that these bacteria actually gobble up the calories. And they gobble up the calories so you don't have to," says Peter Jones, the study's lead investigator.
"It's a cool concept."
The findings will be published in an upcoming edition of the Journal for Functional Foods.
Probiotics are big business for yogurt companies. Most people have heard of probiotics, thanks to yogurt advertisements that have touted the benefits of these bacteria for digestive health.
In a clever marketing tactic, some companies have even named their specific strains of probiotics to help spell out to consumers the supposed role of the bacteria. (One example is Activia yogurt's bifidus regularis and the suggestion it promotes regular bowel movements).
Quebec biotechnology firm, Micropharma, funded Jones' study, which cost nearly half-a-million dollars. The company is currently working with Danone, the French yogurt company that makes Activia.
Probiotics might mean big business for the food industry, but the role of probiotics and weight is also one of the hottest areas of research for obesity specialists.
Jones, a nutritional biochemist, says reputable studies have shown that overweight animals have the wrong balance of bacteria in their stomachs -- too much "bad" bacteria and not enough good.
"If you change the types of bugs in your gut, those bugs actually metabolize energy which would otherwise be absorbed and laid down as new fat," he says.
That leads to the question: Do overweight people tend to carry bad bacteria in their stomachs because of the very fact they are overweight? Or vice versa?
"We'd like to think it's the other way around," says Jones, noting that bad bacteria in the gut could be one of the complex factors contributing to obesity. "We'd like to think that there are lazy and there are energetic bacteria in the gut. When you have lazy bacteria in your gut, basically those bacteria just kind of lie around. Basically, they are couch potatoes."
The RCFF study was what scientists call a randomized, double-blind crossover trial in which participants were each given three dietary treatments; a control meal containing no probiotics; one containing lactobacillus fermentum; and the other containing lactobacillus amylovorus. Individuals were fed each treatment over six weeks followed by a "wash-out" period to clear the person's system before proceeding to the next treatment.
The probiotics that the participants consumed were in a yogurt preparation.
Participants promised they wouldn't eat any other food other than the meals the RCFF provided them.
"This was really robustly controlled. These studies are massively expensive and require huge amounts of input in our kitchen," says Jones, director of the RCFF. "We have a miniature army of undergrad students from nutrition and food science all cooking up these meals for volunteers and weighing everything out."
Each participant's fecal matter was tested to measure gut flora before and after each treatment.
The study confirmed that lactobacillus amylovorus caused "a significant reduction" in clostridial cluster IV, an unhealthy bacteria related to c.difficile, the bug that has caused serious illness to hospital patients around Canada.
The four per cent fat loss was measured using a dual-energy x-ray absorptiometry (DEXA) scanner.
So, what's the big deal?
"Four per cent over six weeks doesn't sound like a deal maker but just do the math. Take it out for a year or a decade and you're talking about ... a pretty sizable change," says Jones.
"And that was fat loss," says researcher Jaclyn Omar.
Should consumers assume that consuming probiotics is the answer to weight loss?
"That is the idea -- that you can have your cake, or in this case, your yogurt, and eat it too," says Jones. "The notion being that's all you really have to do is change the type of bugs in your gut -- which is totally consistent with the work of the leaders in this field.
"It is almost too good to be true. But we're really keen on following up on this study to confirm these results."
Jones says unhealthy gut flora is just one piece of the obesity equation. He says we live in an "obesogenic" environment in which people tend to eat too much and move too little.
Dr. Arya Sharma, an Edmonton-based physician and scientific director of the Canadian Obesity Network, says although the study did not show that probiotics help people lose significant amounts of weight, it does suggest that they may aid in weight management and fat loss.
"How strong this effect will be, how long it lasts, and whether or not any such changes actually result in improved health or reduced risk for diabetes or heart disease certainly remains to be seen," Sharma says in an email.
He cautions consumers to be careful about the weight loss claims yogurt companies may make in the future.
"Although there may be a strong drive to use these results to drive sales, it is important to recognize that the long-term efficacy and benefits of probiotic supplements or foods has yet to be demonstrated."
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Probiotic and obesity
The research: A $500,000 Winnipeg's Richardson Centre for Functional Foods study suggests that people who consume probiotics (the so-called good bacteria found in foods such as yogurt) will reduce their body fat.
How: The probiotics, which are live bacteria, might actually digest calories before they are stored and turn into fat, according to the study's principal investigator.
Current status: There is a lot of buzz surrounding probiotics as companies develop their own strains claiming they do everything from promote digestive health to boost the immune system.
What the past research says: People who are overweight tend to have more "bad" bacteria in their guts and not as much "good" bacteria as their slimmer counterparts.