In articles published on this website, writers have pointed out many of the problems causing America’s – and the worlds’ – growing obesity epidemic. These causes include a shift in our diets away from fresh fruits and vegetables in the direction of processed foods containing far too much sugar and fat, and the increasingly sedentary lifestyle that many of us lead, glued to the TV or to our computer screens, getting far less exercise than we need.
But two recent studies in a new field of study are suggesting that the overuse of antibiotics may also be contributing to the obesity epidemic by disrupting the bacteria in our gut, causing us to pack on fat in the same way that farm animals do.
What is the microbiome?
One of the most interesting new areas of study in the field of biology is the study of the microbiome – the veritable army of bacteria, fungi, and viruses that live inside our bodies, and that are critical to our metabolic process. Without them, we would literally be unable to process and digest the foods we eat.
And when I use the word “army” above, I’m being literal – for every human cell in our bodies there are 10 of these microbial cells. To paraphrase Walt Whitman in his poem Song Of Myself, “We are large; we contain multitudes.” The microbiome comprises a complex inner ecosystem, one that is critical to our lives as human beings, and to the physiological processes that enable us to keep living them.
Antibiotics disrupt these inner armies of microbes, killing some and altering the functioning of others. This can lead to what scientists have called “microbe-induced obesity,” caused when the gut bacteria that are supposed to convert the foods we eat to muscle and normal bodily growth start converting it instead to fat. Although antibiotics certainly have their place in helping human beings to rid themselves of diseases, it is interesting to note that 80% of all the antibiotics used in America are given to farm animals. This is not done for the purposes of curing them of diseases or preventing them; it is done to fatten them up. Animals fed low doses of antibiotics grow larger and faster than they usually would, and thus become more valuable in the market.
Are antibiotics fattening us up like farm animals?
Two research studies published in recent months suggest that the answer to this question is yes. In the first, published in a paper in the journal Nature, microbiologist Martin Blaser and his colleagues fed low but steady doses of antibiotics to laboratory mice. When they examined these animals’ microbiomes, they found that profound changes had taken place in their gut bacteria. Changes were also found in the animals’ genetic structure that affected their ability to break down carbohydrates and regulate their cholesterol levels. The result was similar to what happens to farm animals; the mice did not gain weight, but their percentage of body fat increased by 15 percent.
Blaser took his findings from the mice study and attempted to see if he could find a counterpart in human beings. In a paper published in the International Journal of Obesity, he reported on a study that looked for trends in 10,000 British schoolchildren.
What he and his colleagues found was that children who had been exposed to antibiotics before they were six months old displayed small but significant increases in body mass in later years. Again, the antibiotics appeared to have modified the gut bacteria that controlled their metabolisms, causing them to store more of the foods that they ate as body fat.
Although both of these findings are preliminary, they are unsettling for a number of reasons. First, humans are being prescribed more and more antibiotics by doctors, which may affect their bodies’ microbiomes and contribute to them becoming obese. But even more of a concern is that the effects found in these studies were caused by low but steady amounts of antibiotics. Because many of the meats we eat still contain traces of the antibiotics fed to the farm animals as they were being raised, we ingest them every day. If the early results suggested by these studies prove to be true, we could literally be “fattening ourselves up” in the same way that the farm animals we eat have been fattened up by giving them antibiotics.
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