What is a probiotic?
I fear that as the word ‘probiotic’ becomes increasingly recognized as a therapeutic term, and gains more mindshare, corporate interests will attempt to disassociate it with food, so that they can associate it exclusively with their ‘proprietary’ manufactured products. We cannot let that happen.
In 2002, the world actually established a formal definition for a ‘probiotic’ in these words:
“Live microorganisms which when administered in adequate amounts confer a health benefit on the host” (FAO/WHO, 2002). In 2014, a consensus panel reiterated the definition, with one small change replacing “which” with “that” (Hill et al., 2014).”
That definition is from the World Health Organization, and it is pretty straight forward and easy to understand. Nowadays, just about everyone knows that something like yogurt is a probiotic.
I go a bit deeper into the issue in a video here: What is a Probiotic?
The guidelines for ‘proving’ that something ‘confers a health benefit’ are more complicated, as you can imagine, but it doesn’t change the basic understanding. Sadly, some scientists conflate in vitro tests with in vivo realities, claiming that microbes from fermented foods cannot survive our stomach acids, enzymes, and other challenges along the digestive tract. These claims are false for at least two reasons:
- The shear volume of probiotics (and the complex matrix of other organic compounds accompanying them) in fermented foods cannot be overwhelmed by our digestive tract. In fact, we often rely on them to help us digest other foods. Consider that a glass of kefir probably has more microbes than ten or twenty bottles of probiotic supplements. And consider what happens to your stomach pH when you consume a glass of anything… it dilutes. Also consider that we rarely eat probiotic foods in isolation, but as part of complete meals.
- Even if our digestive system was powerful enough to kill every microbe in a fermented food serving (which it certainly can do sometimes) the dead microbes are still valuable (as explained below). This scenario is explained explicitly by the various alphabet agencies that are trying to enforce the definition.
Many thousands of scientific studies have shown the health benefits of various probiotic foods, and show solid evidence that the microbes we consume in fermented foods are often populating our guts. And for me, more importantly, many cultures have demonstrated robust health on a diet high in fermented (i.e. probiotic) foods.
As humans, we evolved with probiotics for many thousands, of years, whether from our food or from our environment. In fact, we evolved in a probiotic environment for millions of years. It is only our very recent generations that have been getting starved from probiotics due to isolated or sterile environments, antibiotics, pollutants, and more. Thus, some of us have come to rely on making explicit efforts, via food, supplements, or both, in order to bring back the important microbes that help keep us healthy… and make us human.
Probiotics are a booming market, and rightfully so, as they are saving many lives. I am glad that we have companies making probiotic supplements, as they are often needed in our modern world.
A Dilemma Emerges
Unfortunately, as mentioned above, a few scientists claim that yogurt is not a probiotic. Not only yogurt, but kefir, sauerkraut and more. They claim that they do not pass the WHO definition of what a probiotic is. Why? I honestly cannot speak to their motivations, but the assertions are incorrect. But why might they be saying this?
Well, most yogurt, probiotic pills, sauerkraut, etc. are NOT effective probiotics. But this is simply an issue of quality, and not an issue of definition. Even the FDA agrees, as you can see in their definition:
“Probiotics are live microorganisms that are intended to have health benefits when consumed or applied to the body. They can be found in yogurt and other fermented foods, dietary supplements, and beauty products.”
You can read the FDA’s entire page here.
Sadly, too many of our ‘modern’ foods and probiotic pills are highly processed products that have a poor (or dead) microbial makeup. So… I can almost agree with some scientists when discussing specific products; however, they are nonetheless incorrect in categorically claiming that kefir or sauerkraut is not a probiotic. This is a problem that I hope we can get them to correct.
I must add, even when considering the ‘worst’ products, it would still be hard for me to agree with them, as it is far more complex than we can yet (or perhaps ever) understand. For example, one can make quite a strong case that even the ‘bad’ probiotic pills are still valuable probiotics, because even if 100% dead, their DNA/RNA may still contribute positively to the genetic diversity of your microbiome, and even trigger various human biological functions.
I hate the idea of all the ‘fake’ probiotic pills, so I would love to ‘tighten’ the probiotic definition; however, I cannot provide the science to deny the product claims of the bad products. The only thing I can say is that some probiotics are far more effective than others, and even then it is still a very personal matter, and our science will always be limited. A terrible probiotic is still a probiotic.
‘Real’ Kefir, sauerkraut, yogurt, kimchi, and other fermented foods, are all very powerful probiotics that have contributed to human health for thousands of years. There is no question about it.
Don’t take my word for it… read for yourself what the WHO, FAO, ISAPP, FDA, and other agencies say. Or go and see the countless studies on PubMed and elsewhere that show the probiotic power of fermented foods.
https://nccih.nih.gov/health/probiotics/introduction.htm
https://www.longdom.org/open-access/probiotics-history-and-evolution-2329-8731.1000107.pdf
https://isappscience.org/about/mission-and-values/history/
https://www.who.int/foodsafety/fs_management/en/probiotic_guidelines.pdf
