Probiotics: Myths and Mysteries

"I'm supposed to take some [guy's] word that it's full of good bacteria.
Don't trust 'em. I always stir in a spoonful of Purell® first."
~Stephen Colbert, The Colbert Report.
Bacteria are a key part of your immune system that you may not think about too often. The average human actually carries 2-6 pounds of the microbes, and they outnumber the cells in your body 10 to 1. It's no surprise then, that people have begun to investigate how your microbiome might influence your immune health.

The term "probiotic" was coined by scientists Lilly and Stillwell in the 1960s (their paper can be found here). Probiotics are defined (by the World Health Organization) as live microorganisms that, when administered in adequate amounts, confer a beneficial effect on the health of the host. Several food companies have jumped onto the probiotic bandwagon. Food industry companies like Danone promote their probiotic features, and there’s even a pizza company that boasts of heat-resistant bacteria baked right into the crust. The basic belief here is that you can add bacteria to your body that help to balance it out, i.e., to use the good bacteria to counteract the bad. But, how true are these claims of improving your gut health?

Bacteria in the crust is just as good as cheese, right? Check out their website. The Fresh Prince of Bel-Air, NBC Productions.

It’s not as cut and dry as "good" or "bad" bacteria. Image from Al Nisbet.
Two of the most common genera of probiotic bacteria are Lactobacillus and Bifidobacterium. These genera are preferred due to their proven safety track record. What is important to note is that the probiotic effect is often species specific. You cannot simply lump the entire genus of Lactobacillus as a "good bacteria" or call another group "bad bacteria". In fact, back in grad school, a lab close to mine found that feeding diabetes-prone rats one strain of Lactobacillus mitigated development of Type 1 Diabetes, while another strain couldn’t (see the paper here).
So what are the potential health benefits of a probiotic strain of bacteria? To date, there has been documentation on probiotic ability to treat/prevent diarrhea, boost innate immunity, and aid in allergy prevention. There have also been some claims that it can help those with Irritable Bowel Syndrome and Crohn's Disease. Of course, further studies are needed to confirm these results, standardize the testing, and determine the mechanisms of action.
Even with these intriguing possibilities, probiotics pose several questions that the industry and scientific community need to address:
  • Are they potent enough to permanently alter the composition of bacteria in your microbiome?
  • Is the food label on the food product accurate concerning the number of bacteria? Does it account for bacteria that won't actually survive your stomach's acid?
  • How many bacteria will actually be able to colonize the gut?
  • How do you standardize measurements of probiotic-induced health benefits?
  • Are there some parameters more valuable to measure than others, such as immune cell counts?
  • Will you have to tailor a probiotic treatment to the individual’s unique microbiome?
In summary, there are a lot of factors to consider about the effectiveness of probiotics. It’s important to realize that companies can oversell a probiotic's impact through advertisement. In fact, Danone was sued a few years ago for $45 million when their probiotic claims were labeled as false advertisement. Although they claimed no wrongdoing, they were forced to remove the terms "clinically", "immunity", and "scientifically proven" from their labels. They also had to indicate their product is not a treatment or cure for any medical disorder/disease. Probiotics are an emerging field of science that could offer some real advancement. However, it's always best to be skeptical and demand scientific evidence before you start buying cases of yogurt.
Danone got in hot water for their probiotic advertising.
What do you think about probiotics? Let us know here. You can also check out the links below to learn more about probiotics.
Danone Settles Probiotic Lawsuit.
Current Level of Consensus of Probiotic Science.
Probiotics: Facts and Myths Journal Article.
Is Yogurt Good for You? The Pros and Cons of Probiotics.
Huffington Post: 5 Common Probiotic Myths.
Dr. Mary Sanders Seminar on Probiotics.

Just when I think I got the hang of science...
Contributed by Ken Lau, PhD.
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