Good Bacteria = Smaller Waistline?

Research in the area of normal flora — the “good,” or beneficial bacteria that live in our gut — has been exploding in recent years.  It has been known for a long time that supplementing with probiotics (those friendly bacteria like Lactobacillus and Bifidus) can help with conditions ranging from eczema to allergies to irritable bowel syndrome.  But the list of benefits of proper microbial balance keeps growing — and it seems like the more we know, the more we realize how much we don’t know yet.

Recently, Chinese researchers (1) found a connection between the microbes in our gut and the problem of obesity.  Mice that were bred to be resistant to obesity, in spite of a high-fat diet, rapidly gained weight when injected with a bacteria from the human gut called Enterobacter cloacae.  They hypothesize that a harmful substance produced by these bacteria, called endotoxin, contributes to insulin resistance.  Insulin resistance is a major contributor to overeating and obesity, and the hallmark of type 2 diabetes.  Think of insulin as a key to open the door to your cells so they can take in blood sugar for energy; insulin resistance is where the lock on the cell doors gets worn and rusty, making it more difficult for insulin to do its job.  Insulin levels rise, which contributes to widespread inflammation in the cardiovascular system, and promotes fat storage.

In the same article, the researchers report a case study of a man who lost 66 pounds in 9 weeks by switching to a diet that promoted good bacteria growth in the intestinal tract.  The harmful Enterobacter was reduced to undetectable levels.

Now before you pop an acidophilus supplement or grab a Yoplait, expecting miraculous weight loss, we need to look a little more closely at the diet supplied to this test subject.  It was very high in fiber, to feed the good bacteria in the gut, and also included traditional Chinese fermented foods that might seem challenging to our palates.  Fermented foods are beginning to look more important than probiotic supplements, simply because of sheer numbers:  supplements might have anywhere from 1 billion to 20 billion bacteria per serving, which sounds like a lot, until you realize that there are about 100 trillion bacteria in your gut!  Traditional fermented foods have much higher levels of good bacteria than supplements.  We’re not talking about most commercial yogurts, which are crammed with sugar and have questionable amounts of active bacterial cultures; we’re talking about plain yogurt, kefir, miso, traditional sauerkraut, and kimchi, to name a few.

We’ve barely scratched the surface on research into our normal flora — not just in the gastrointestinal tract, but also on the skin, respiratory tract, and genitourinary tract.  It makes sense that they would have such a huge influence on our health:  there are ten times as many bacterial cells as human cells in our bodies!  We are really more of an ecosystem rather than a single organism.  Perhaps in the future there will be much less emphasis on therapeutic nutrition, except as it applies to how it influences our flora.

1.  An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice.  The ISME Journal advance online publication 13 December 2012; doi: 10.1038/ismej.2012.153

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