Antibiotics, yeast and allergies

I know that the prevailing view is that allergies are genetic, but I disagree and for years I have been telling my patients or their parents that allergies come from the gut. Although some people do pay attention when I say this, more often than not I see eyes roll in disbelief.

Finally, a new study from the University of Michigan Medical School (Infect Immun 2005 Jan; 73 (1): 30-8) confirms just what I have been preaching all along, and I couldn’t have said it better myself!

Researchers started out with healthy laboratory mice and treated half of them with antibiotics. As pointed out in the study, in addition to killing their intended targets, antibiotics also disrupt the intestinal flora and enable the yeast Candida albicans to grow unimpeded. This outcome is further aggravated by a high sugar and refined-carbohydrate diet; just what children (and many adults) eat today.

Next, researchers exposed both groups of mice to an airborne allergen, the same kind of thing you and I are breathing all the time right here in Houston, and – surprise! – only the mice pretreated with antibiotics developed asthma or allergies. Suspecting this may have something to do with their genetic makeup, researchers also used mice with different genetic characteristics but still got the same result.

A statement from one of the lead researchers in this study is amazing. I think I’ll frame it: “Our research indicates that microflora lining the walls of the gastrointestinal tract are a major underlying factor responsible for the immune system’s ability to ignore inhaled allergens.”

As it turns out, a type of white blood cells called “regulatory T cells” – discovered only a few years ago – are formed in the intestinal tract and later migrate to the lungs. There they “teach” the rest of the immune system how to distinguish true enemies such as viruses from harmless substances like pollen. Yeast in the gut produces chemicals that disrupt the formation of these immune cells, and then it’s only a matter of time until something goes awry.

The researchers end their report with a warning that this study should not be viewed as a reason to avoid antibiotics. I understand that researchers need to show their loyalty to the drug companies that pay their bills, but frankly I disagree. Antibiotics should seen for what they are: potentially lifesaving but still dangerous drugs that should be used with caution.

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