The human body and nature itself never cease to amaze me. It’s fascinating to me that so many times that we humans learn about something that is involved in human health, we end up thinking that we know more than we actually know. Our knowledge of our gut microbiome (formerly called gut flora), is the microbe population living in our intestine. The European Society of Neurogastroenterology & Motility reports it to contain tens of trillions of microorganisms, including at least 1000 different species of known bacteria with more than 3 million genes (150 times more than humans, who have less than 20,000 genes). Just the sheer number of microbes and genes is enough to lead us to believe that we’re just at the beginning of understanding our microbiome.

An intriguing recent story which came out of a study done in Israel and published in the journal Cell in September 6, 2018 has caught my attention. Many of you will want to read the study, but let me give you a quick layman’s idea of what was learned. The researchers were trying to learn if taking probiotics after being medicated with antibiotics was effective or not. They randomly assigned 21 healthy adults to three groups after a week on antibiotics. The three groups assigned to were:

• They would get no additional treatment (the control group)
• The second group got a fecal transplant, which was made from their own microbiome before they took the antibiotics
• The third group took a probiotic for four weeks. The probiotic contained eleven of the most commonly used bacteria in the probiotics market.

Now here’s the interesting outcome:

• The microbiome of the control group returned to their initial composition after four weeks.
• The fecal transplant group was no different from its original composition just one day after transplantation.
• The probiotic takers didn’t return to normal. “They had microbiome characteristics that were suggestive of pathological states, such as low bacterial diversity and sustained microbiome imbalance;” said Eran Elinav, a professor of immunology at the Weizmann Institute of Science where the research was done.

At first glance, you may say; obviously the fecal transplant is the best choice. But that is not something that you do at home after recovering from your infection and the antibiotic that cured it. Even more interesting is the fact that the researchers continued to test the probiotic group for six months after the course of antibiotics and that group’s microbiome never returned to normal. Although the researchers do not know what the changes mean for health, they believe that it’s not likely to improve it. Elinav was quoted by Nutrition Action Newsletter as saying; “Contrary to the current dogma, which says that probiotics are harmless and benefit everyone, our results point out that consumption of probiotics following antibiotics can delay the restoration of a person’s microbiome. If our intent is to restore the microbiome to its initial state, probiotics are clearly not the preferred means to achieve it. We need high-quality studies to further assess this potentially alarming adverse effect of probiotics after antibiotic use.”

I look forward to the results of the further research with larger and more diverse samples that should come from this work. Some questions that pop out of my head are:

• What about populations that eat probiotics as staple foods? Certainly, many of them were eating the foods long before antibiotics were discovered. If this is all verified it seems that it opens a huge can of worms that need to be addressed.
• A related question is: What about those that ate probiotic containing foods prior to the antibiotics?
• If we eat a fairly common American diet, should we avoid live culture yogurt and cheese, after a round of antibiotics?

Some foods that contain probiotics are:

• Yogurt with active or live cultures (all yogurt starts with live cultures, but sometimes in the processing the bacteria are killed. Note: Some yogurt is loaded with high amounts of added sugar.
• Kefir is a fermented probiotic milk drink
• Sauerkraut is fermented cabbage – nutritious, but very high in salt; pasteurized sauerkraut kills the live and active bacteria
• Tempeh is fermented soybeans
• Kimchi is spicy Korean fermented cabbage
• Miso is fermented soybean paste, Japanese seasoning
• Kombucha is fermented black or green tea
• Pickles (that are fermented in salty water) it does not include those with vinegar, as vinegar kills bacteria
• Buttermilk that is fermented (popular in India, Nepal and Pakistan) American cultured buttermilk does not have probiotic benefits
• Natto is another fermented soy product popular in Japanese cuisine
• Some types of cheese, including cheddar, mozzarella and gouda

Although the results of this study offer many questions, the small-sample research was well conceived and well done. If these results hold up with larger samples, it is more than worth-while knowing about the results, so the next time your physician says to load up on probiotics after a round of antibiotics, you will know to ask if he/she is familiar with this study.