Intestinal Bacteria and Weight Loss

Studies are indicating that the workings of our intestinal flora--the bacteria in the intestines of normal, healthy individuals--affect fat storage. This suggests that these microbes might hold one more key to understanding obesity.

Viruses: a new player in the gut

It turns out that communities of viral predators in our intestines, called phages (or virus-like particles, VLPs), have a great affect on our intestinal microbes (gut flora). That's right: These VLPs can help or hinder our digestive processes, depending on whether they're healthy or not.

Then the last logical question is, what circumstances or entities or conditions act on these VLPs or phage colonies in our intestines? This is an important question because whatever is influencing the VLPs is also going to have a large say in determining the health of our intestines. Does inherited genetic information from our genome (aka our genetic code) mostly determine how these VLPs behave? Or is the healthiness of our lifestyle and environment a more important influence on them?

Interestingly, a recent research study done at Australia's University of Queensland and published in the July 2010 Nature has shown that our personal health and dietary habits--and not our genetic inheritance--have the greatest influence on the the actions of these intestinal phages.

A clever study of twins

The scientists behind this research were clever: They studied the digestive tracts of mothers and their (identical) twin children. Why identical twins? Because they share a matching genome; that way, the scientists would know that any large differences between the microbes inside the twins' intestines were due to their day-to-day habits, and not to any built-in encoding by their shared genome.

The researchers studied the mothers and twins at 3 time points over a 1-year period, and discovered that the intestinal viruses--and therefore the intestinal microbes--in the 2 twins' guts did indeed vary greatly. And those variations between the twins had to be due to diet and lifestyle, not genetic factors.

To sum up

  • Our gut microbes affect how our bodies store fat, and thus might influence our weight.
  • Our gut microbes are in turn affected by intestinal communities of virus-like particles called phages.
  • The actions of these phages are in turn greatly influenced by our personal health behaviors and dietary habits.
  • How our bodies handle fat is in part determined by our personal actions and habits.

This research study tells me that we really may be able to nurture the good bacteria in our guts and influence our "bacterial neighborhoods," more than we think. In fact, paying some attention to our intestinal flora just might help us deal more successfully with our weight.

Pampering our good bacteria

And how can we pay more attention to our intestinal flora? By ingesting more probiotics--types of good bacteria that promote healthy digestion, boost the immune system, and contribute to general health and wellbeing. And we can also make sure that we eat more prebiotics--substances that the good bacteria like to eat.

  • Probiotics are found in yogurt and soy yogurt, kefir, cottage cheese, sauerkraut, pickles, sourdough bread, miso, tofu, tempeh, tamari, and buttermilk.
  • Prebiotics include barley, wheat, onions, bananas, garlic, leeks, beans, soybeans, and whole grains, as well as foods and drinks fortified with these substances.

We in the U.S. must catch up

It turns out that we in North America are lagging behind in this department, consuming only about 1 gram to 4 grams of prebiotics a day, compared to the average European, who is estimated to consume 3 grams to 11 grams a day. Of course, if you're watching your weight, always choose low-fat, low-sugar versions of cottage cheese, yogurt, and the like. (One word of warning: If you ever need "prescription-strength" probiotics for a medical condition like ulcerative colitis, please check first with your doctor and dietitian, since it's difficult to get a healing dose of these good bacteria through foods alone, and probiotic supplements vary greatly in quality.)

Seeing this research, I'm hopeful that improved understanding of the viral and microbial communities residing in our guts will result in better, more personalized dietary advice, or even in the creation of new strains of probiotics to bolster our health and wellbeing.

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