Gut Feelings or Gut Research? The Ultimate Probiotic Guide

This weekend, I attended the Taking Control of your Diabetes conference at the San Diego convention center, where I was lucky enough to learn about up and coming technology and research in diabetes treatment.  Particularly enlightening, was the session on the gut microbiome taught by  Amir Zarrinpar MD PhD., and it seemed to come at an opportune time.  Over the course of this week, I have been asked on three separate occasions by different people for my opinion on probiotics.  Now, before I get into the nitty gritty of probiotics and your gut, I want to make it clear that this is a relatively new course of study.  Prior to a couple of years ago, we believed that our gut microbiome was a static environment, unchanged from birth.  We now know how very wrong that notion is; however, modern research is somewhat inconclusive on how much probiotics can actually affect your gut flora.

What are probiotics?

Many of us have heard that probiotics are things found in yogurt that can help relieve some common tummy woes, but did you know that probiotics are actually living microorganisms?

Now some of you may be asking what I mean by microorganisms.  Two common examples are bacteria and yeast.  Yep, news flash germaphobes of the world, but your worst nightmare might actually aid in digestion.  Oh yeah, and also live in your gut, and all over your skin.  In fact, it is estimated that we are 52%-90% bacterial!  Many of the microorganisms found in probiotics are the same bacteria or at least similar to those found in your body that help digest food, protect you from other bad microorganisms, and even produce vitamins; however, there is still some speculation about the effectiveness of taking probiotics.

Are probiotics Effective?

There is actually some research to suggest that probiotics may help or prevent the following:

However, let’s not be too hasty to proclaim probiotics a miracle cure.  Strong scientific evidence to support the use of probiotics in certain health conditions is lacking.

In the talk Dr. Zarrinpar gave on Saturday, he was highly skeptical of probiotics for the following reasons:

  1. There is no evidence that probiotics cause a change in the gut microbiome of humans.
  2. Probiotics often don’t make it to the colon, and are destroyed by the acidity of the stomach.
  3. Even if they make it to the colon, they often can’t “hang out” in such a competitive environment.

We also must gain a greater understanding of what specific bacterium play a role.

What you see on the back of a container:

The two most common classes of bacterium you’ll find in probiotics are Lactobacillus and Bfidobacteria.  Please note that these are broad groups of bacterium and not a specific kind species like many would assume.  Under these classifications there are a variety of species of bacteria, most of which, we have little information on what role they play (remember this is a relatively new course of research).  That being said, there have been a few studies linking specific strains with certain beneficial effects, for example:

  1. Lactobacillus GG and Bfidobacterium spp. has been shown in a couple of controlled studies to shorten the effects of infectious diarrhea in children and infants.

Dysbiosis and Disease

So far, we have touched upon some of the research available on probiotics, but why are we so concerned with our gut health anyways?

Dysbiosis is a term for microbial imbalance, and it’s been linked to obesity, diabetes, and even autism.  It turns out that more important than the composition of the gut, is the genomes of the microbes.  Research has suggested that the genes in the bacteria in our gut can actually influence our own gene expression to a certain extent, which is pretty crazy to think about.  This means that the more we know about specific gut bacterium and its link to certain diseases, the more progress we can make in preventing and treating specific conditions from the gut up.

Gut Feelings

Although the research is inconclusive, probiotics could be helpful in treating certain conditions.  Although I wouldn’t advise you to run out of your house and raid the probiotic aisle of your local health store, it can’t hurt to have a bit of yogurt, kimchi, sauerkraut, or take a supplement every once in a while, and it may even help.



If you’re curious, here are a few of the studies I referenced:

Effects of probiotics on the recurrence of bacterial vaginosis: a review.Homayouni A1, Bastani P, Ziyadi S, Mohammad-Alizadeh-Charandabi S, Ghalibaf M, Mortazavian AM, Mehrabany EV.

Probiotics for children with diarrhea: an update.  Guandalini S1.


The Effect of Probiotics on Prevention of Common Cold: A Meta-Analysis of Randomized Controlled Trial Studies.  En-Jin Kang, Soo Young Kim,corresponding author In-Hong Hwang, and Yun-Jeong Ji

Probiotics and Liver Disease.  Vishal Sharma, MD, DM, Shashank Garg, MD, and Sourabh Aggarwal, MD



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