A study recently published in Nature seems to be causing a ripple in the media. In summary, it says that “good" bacteria (from the Phyla Firmicutes, which includes most of the bacteria found in probiotic formulas such as acidophilus) make people fat, whereas “bad" bacteria (Phyla Bacteroidetes) make people lean. To put it in simpler terms: according to the study, when it comes to losing weight, the bacteria that we used to call "good" (L. acidophilus, L. salvarius, L. bulgaricus, L. plantarum, etc) are "bad." And bacteria that we used to think of as "bad" are in fact "good." Isn't that a head spinner?
But it gets even more interesting. In a companion study, they found that the ability to lose weight seems to be transferable -- at least in mice -- by transferring "bad" bacteria from the bowels of lean mice into fat mice. Based on this study, some medical authorities in the media are predicting a whole new way to treat obesity by transferring "bad " bacteria into the colons of overweight people. (Don't think about that too much. It can conjure up some rather unpleasant images.)
Before you panic, though, a quick reality check.
The Study on Bacteria
In essence, the studies found that good bacteria are more efficient at extracting value (including caloric value) from food. That means that if two people eat the same amount of food and exercise the same amount, the individual with more good bacteria will put on more weight. The study reported results on 12 obese patients tracked over a year. Half of the patients were put on a calorie-restricted low-fat diet, and the other half were on a calorie-restricted low-carbohydrate diet. The authors monitored their gut flora by analyzing stool samples. At the beginning of the study, the patients were low on Bacteriodetes bacteria and had higher counts of Firmicutes. But as they lost weight, the proportions in both groups began to shift. Bacteriodetes as a group (not just one or two species), enjoyed a population boom, and Firmicutes dwindled in number. In other words, just cutting calories and losing weight (regardless of the type of diet used) was enough to "favorably" change the ratio of bacteria in the bowel.
So, does that mean you should immediately throw out your probiotic formulas and drink lots of chlorinated water to kill off all the acidophilus in your gut to lose weight? Not necessarily.
Correlation for Obesity is not necessarily cause
In no way do the studies prove that good bacteria cause obesity -- only that bacteria populations change as a result of diet, and that bad bacteria limit the value you get from what you eat.
Step back for just a moment and think objectively.
- If beneficial bacteria make you fat, then why is obesity generally seen in people who eat junk food, consume commercial meat and dairy that contain antibiotics, and drink water that contains chlorine -- all things that destroy beneficial bacteria? According to the studies it should be just the opposite -- these people should have higher counts of beneficial bacteria in their intestines?
- Why are people who eat healthy and take probiotic supplemements generally fitter and leaner? Theoretically, they should have higher counts of beneficial bacteria, but according to the studies it should be just the opposite.
- Or if you follow the studies to their logical conclusion that obesity is not your fault -- it's the result of a genetic quirk that gives some people a bacterial advantage in staying thin, then why are we seeing a surge in obesity throughout the world now. The number of obese people should have grown in direct proportion to growth in population -- not explosively above and beyond that. We also shouldn't see thin people growing up in one culture suddenly getting fat when they move to another country and adopt their new country's lifestyle. A little commonsense here, please.
Instead of looking at a couple of isolated studies, step back for a moment and look at the big picture. Obesity is the result of diet and lifestyle choices -- of consuming more calories on a daily basis than you burn. In America, 65% of adults are now overweight, and half of those are considered obese. The proportion of children who are overweight has gone from 7% to 15% over the last 20 years, and the proportion of overweight adolescents has risen from 5% to almost 16%. And as the rest of the world adopts the American diet, it's following closely behind with obesity surging throughout Europe and China. Plain and simple, this is the result of a fast food/snack food diet combined with reduced exercise -- not bacteria in the gut.
That said, does that mean the studies are meaningless? Not at all. There's no question that some intestinal bacteria are better than others at breaking down food and extracting value than others. But (and here's the million dollar question) is that necessarily a bad thing?
A Perspective in Beneficial Bacteria
- Extracting more value from food (remember, that includes vitamins, minerals, and phytochemicals in addition to calories) might actually be a good thing. It's only a problem when you're eating too many of the wrong kind of calories!
- Or to look at it another way, do bad bacteria merely offer you a form of internal bulimia? Instead of having to throw up the food that you eat, do the bad bacteria allow you to digest the food, but not extract full value from the digestion -- as if you threw it up? That can't be good.
- Beneficial bacteria play a number of major health roles in the human body, including providing up to 60% of your immune function. Do you really want to get rid of the good bacteria and crush your immune system?
- As soon as you go on a reduced calorie program, your intestinal bacteria begin modifying their populations to accommodate the changes in your body. Form follows function.
- The studies analyzed the bacteria in stool samples, not throughout the gut. This may provide very misleading data. In a healthy person there shouldn't be many acidophilus bacteria in the bowel. Most of the Firmicutes bacteria should reside in the small intestine. A healthy stool should indeed show a high proportion of Bacteroides in stools -- along with Bifidobacteria (which are part of an entirely different Phyla, Actinobacteria) and even a few E. coli (Phyla, Proteobacteria). A high proportion of Firmicutes -- in the bowel -- is indeed not ideal and is unlikely to be seen in individuals with properly populated intestinal bacteria. In fact, everything that we know about probiotics and dysbiosis says that people who eat badly and are obese are far more likely to have reduced populations of beneficial bacteria throughout their small intestine where they are needed, as opposed to the bowel where they are not.
Key Points about Obesity and Probiotics
- Don't panic.
- Consume fewer calories.
- Exercise more to build muscle mass and speed up metabolism to burn more calories.
- Minimize fast food and junk food.
- Eat nutrient dense foods, foods that provide a high level of nutrition with minimal calories.
- Regularly clean out your colon to provide a proper environment for building right kinds of bacteria in each particular area of your intestinal tract.
- Avoid all foods with synthetic estrogens as found in much commercial meat and dairy and even foods with high levels of phytoestrogens as they can cause the body to put on weight.
- Eat more water soluble fiber (psyllium, flax seed, oat bran, etc.)
- And keep taking your probiotics. They are absolutely necessary for good health.