May 25, 2020

We have known for quite some time now that using antibiotics to treat infectious diseases carries secondary health risks. Medical providers and pediatricians in particular have been pushing antibiotic stewardship programs for the past 20 years primarily to fend of antibiotic resistance and the risk of bacterial infections that are untreatable. Unfortunately, the data keeps emerging that the bigger issue with antibiotic use is really the disruption of the intestinal microbiome's bacterial balance that existed pre antibiotic exposure.

Multiple recent and past studies continue to point to an association between antibiotic exposure in infancy and/or childhood and obesity. Let us unpack this statement. First and foremost, is this association or causation? Second, is there a plausible mechanism? Third, are there other explanations for this hypothesis?

This is clearly association and not causation. There is no concrete proof at all that antibiotic use causes obesity. However, this is not to say that it does not nor cannot contribute. There is a bounty of data that is strongly suggestive.

There is a plausible mechanism for this to occur. Every time a person is exposed to antimicrobials, the medicine progresses through the alimentary canal and the blood stream exerting bacterial killing effects on pathogens and commensal bacterial flora alike. This has been well shown in many studies and is not debated anymore. The change in the "normal" flora in the human intestine can change the metabolic function of the host as has been shown in translational studies and in humans as well. The data from translational fecal microbial transplants and human gastric bypass surgery has demonstrated opposing effects on obesity in the recipient with no other variable changes pointing to microbes as the primary driver of the change.

However, there are other possible and complementary explanations for the obese changes. Dr. Azad states, "It is also important to acknowledge that childhood obesity results from multifactorial influences; thus, antibiotic exposure is neither necessary nor sufficient as a cause. However, its potential role cannot be ignored given the mounting evidence from livestock farming, animal experiments, and human studies showing that antibiotics may cause changes in the gut microbiome that are associated with metabolism and weight gain." (Azad et. al. 2020)

We will not do a deeper dive today in the newsletter, but suffice it to say that I have and sit here today convinced that antibiotics are a significantly strong net negative on human health primarily through disruptions to normal human metabolism.


When we look at the effects of COVID 19 on humans, we see death following metabolic inflammatory conditions like hypertension, diabetes and cardiovascular disease. The antecedent trigger to these conditions is primarily related to the ingestion of chronic inflammatory macronutrients that promote inflammasome activation and immune dysregulation. When we look at the multifactorial drivers of obesity, we see that diet, antibiotic exposure, sedentary behavior, exposure to obesogenic chemicals and other triggers are mostly if not completely modifiable by lifestyle choices.

The take home point: Avoid antibiotics if you can. They are not good for you unless you have a bacterial infection that will not self resolve.

Dr. M

Azad JAMA Network Article
Chelimo JAMA Network Article
Baron J Dev Origins of Health and Disease Article