Do These Pills Make Me Look Fat? Antibiotics, Obesity and Other Negative Effects

The discovery of the antibacterial activity of penicillin by Alexander Fleming in 1929 represents one of the singular moments in human history. The number of lives saved is beyond calculation. Medicine was revolutionized by that discovery.

The success of antibiotics is based upon their ability to interfere with a bacterial growth, metabolism, or reproduction. The manner in which they work means that many types of bacteria are affected at the same time by any particular antibiotic, which is termed  ‘broad spectrum.’

Although often miraculous and life saving, people need to be aware that the use of antibiotics has negative effects.

Deep associations between gut microbial composition and diabetes and obesity are now being discovered. A recent surprise has been strong evidence between the administration of antibiotics and increasing childhood obesity lasting into and through adulthood. It appears that the more antibiotics you get as a child, the stronger the effect. The antibiotics seem to be wiping out beneficial populations of gut bacteria and replacing them with others that are less so. The possibility that this might also link to the increasing incidence of Type II diabetes is being further explored.

In the last few decades, the problem of antibiotic resistance has become an increasingly reported clinical experience. Some antibiotics that had been effective against a certain type of bacterial infection have become less so, requiring a higher dosage or more prolonged treatment. In some cases, they might now demonstrate near complete ineffectiveness against a bacterial strain against which they had been highly potent previously.

What lead to this unexpected outcome?  Commonly, it is stated that the bacteria have mutated in response to antibiotics. However, that is largely incorrect. Antibiotic resistance is ancient. All common antibiotics are based on chemicals found in nature and used by other organisms to ward off bacteria. Over eons and long ago, bacteria themselves evolved to counter this form of defense by developing resistance to those defenses. What is occurring in our modern era is that our current antibiotic resistance is leading to an increase in the number of naturally resistant bacteria that become more common within bacterial populations. It is, in essence, a form of selective breeding for bacteria, for the wrong type.

Part of the problem is the pressure felt by physicians to offer antibiotics to their patients. The belief in the power of antibiotics can be very high among patients who are suffering.  Many times, even though the treating physician might assume that it will not be effective, the default can be towards satisfying that demand with the consideration that ‘no harm will be done’.

What we are now learning is that this attitude has been an incorrect assumption. There are other forms of inadvertent harm beyond antibiotic resistance that can occur and these directly relate to the ‘broad spectrum’ capacity of almost all antibiotics. Since they are active against many bacterial types, there is the suppression or eradication of many populations of bacteria at the same time, apart from the specific pathogenic bacterial type that is actually being targeted. When antibiotics are used improperly, the critical balance of many essential bacterial partners in our body tissues is being upset. We do this every time we overuse antibiotics by administering them for the wrong indication. Permitting their use in our food supply compounds these types of errors.

This enlarged understanding stems from the fact that all creatures on this planet including humans are actually vast collaborations between microbial cells, viruses and our own innate cells. In fact, for us humans, microbial cells outnumber our own cells by more than 10 to 1 and are present in all of our body tissues. So when an antibiotic is administered for the wrong reasons, an exquisite balance between an enormous array of microbes and our own cells is being altered for no productive reason. And furthermore, these partnerships between the microbial realm and our own cells serve vital purposes in our health. The range of that interaction can be very surprising. They are intimately connected with our growth and development, metabolism, and even our neurological function and moods.

What happens then if there is a breakdown of these crucial microbial partnerships? It is now known that there are very significant consequences. This has become a well-recognized issue, termed ‘dysbiosis’.

There are now a wide range of examples of these types of effects. An increasing number of diseases are now either being directly attributed to dysbiosis or linked to them. For example, the incidence and intensity of inflammatory bowel disease is now known to be associated with intestinal dysbiosis. Cases of a particularly nasty gut pathogen, Clostridium difficile, are now being actively treated by re-establishing the proper balance of the intestinal flora. Not surprisingly then, antibiotics use is now considered to be one risk factor for the incidence of both of these conditions.

It has been shown that the incidence of both childhood and adult allergy and asthma is on the rise and some research suggests that this, too, is related to antibiotic exposure. Other reports suggest associations between dybiosis and other extra-intestinal diseases such as autism, schizophrenia, rheumatoid arthritis, colorectal cancer and even a tentative association with breast cancer.

What should we do with this new information? Clearly, despite some risks, antibiotics remain essential wonders of our modern medical palette. However, their use should be carefully tailored by physicians for only strict indications. Patients and parents must be willing to accept that antibiotics should not be reflexively requested for many infectious illnesses. And surely, the use of antibiotics in our food supply should be very carefully regulated and restricted.

About Dr. Bill Miler
Dr. Bill Miller has been a physician in academic and private practice for over 30 years. He is the author of The Microcosm Within: Evolution and Extinction in the Hologenome. He currently serves as a scientific advisor to OmniBiome Therapeutics, a pioneering company in discovering and developing solutions to problems in human fertility and health through management of the human microbiome. For more information,

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