A prophet is not without honor, save in his own country! I am sure that after reading this short story you will understand what I mean and maybe even recognize yourself in it.

Last year, my father decided to get his health under control and to boost his immune system. He is eating much better. Gone are the fast food, fries, pop, and late-night chips. He’s introducing color to his plate: lots of antioxidant-rich fruits and fiber-rich vegetables. Also, whole grains and all kinds of nuts. And salmon. The good fats. These are all incredible foods for his body, the best source of nutrients for his cells and his immune system to function properly. And of course, fermented foods like kefir and probiotic yogourt. My dad has lost a lot of weight and his immune health, heart health, and associated diseases have also improved. Quite a turnaround I must say!

His gut microbiota also profits from this cure-all. As a matter of fact, all the micro-organisms that colonize the digestive tract crave this food diversity and this supports immunity. Proteins, fibers, fats, vitamins, minerals, and a plethora of active plant compounds form the basis of the nutritional needs of the bacteria and yeast that live in the gut. My father is a modern man; he has his favorite influencers and listens to them carefully. Recently, it was recommended that he take a probiotic supplement to balance the bacterial populations in his microbiota, which improves his digestive health, supports a strong immune system and his overall well-being. He went to health food stores, pharmacies and even grocery stores to find THE best probiotic. He was surprised to find hundreds of different products, all claiming to be the best and most effective. That’s when he finally asked me for advice on which probiotic he should use. After all, my PhD is in this field!

It is certainly not easy to make sense of it all. There are manufacturers, trademarks, strains, bacteria with intricate names, types, species, billions. One can easily be confused.

Luckily, there are experts and scientists who have a way of simplifying things. Those of the International Scientific Association for Probiotics and Prebiotics have established criteria to help us separate the wheat from the chaff.

The most important factor is without a doubt the scientific evidence (clinical studies). It is important to choose a probiotic with sufficient evidence in a given indication (the health condition studied, e.g., irritable bowel syndrome) for a specific population. There are many different types of scientific studies that lead to different conclusions. Basically, the level of clinical evidence is the ability of a study to address a specific question. In my father’s case, the question is which probiotic is most appropriate to support his gut health.

There are several classification systems defined by health authorities around the world. One of the highest levels of evidence is the randomized controlled trial conducted on many participants, without major bias. A homogeneous population is selected, i.e., participants with similar characteristics (particular disease, physical traits, geographical location, occupations, etc.) and separated into groups of comparable size. Each group will receive either the treatment (the probiotic) or a placebo (sugar pill). Then, all kinds of measurements are made on the subjects and statistical analyses are done to see if significant differences (not due to chance) exist between the groups. If the effects in the treatment group are greater than the control group, then the probiotic product can be said to be effective. When there are several clinical studies on the same product in a given indication, the results can be combined and used to produce a meta-analysis. Meta-analyses are the highest levels of evidence.

Medium levels of evidence include clinical studies carried out on small groups of approximately 10–25 subjects (difficult to generalize conclusions), studies on non-randomized populations or without a placebo, and observational studies.

The lowest level of clinical evidence is testimonials, something like “ever since my uncle took pumpkin seed, he never got sick again.” There are also case-control studies, retrospective studies, and epidemiological studies. The conclusions drawn from these types of studies are difficult to apply or convince because of the large number of biases (lack of objectivity). The effect of the product may be caused by chance or subject subjectivity. In these studies, it is never possible to conclude that the effect is caused by the probiotic product.

So, to help my father choose the right probiotic, I recommend that he ask a lot of questions to the store sales advisors, such as questions related to clinical studies or results of these studies. I also suggest that he refer to the Clinical guide to probiotic products guide to probiotic products, which reviews probiotic products according to the indications studied and the level of evidence.

Of course, I mention to him that Bio-K+ line of products is of very high quality, that they have been clinically studied on more than 100,000 participants in studies of various levels of evidence. Of these studies, Bio-K+ has been tested in at least five randomized controlled trials and has been the subject of at least two meta-analyses. There are also about 30 preclinical studies to understand the mechanisms of action of this probiotic as well as studies demonstrating that Bio-K+ is safe for human consumption.

Yet, my father is no longer listening to me. He’s fascinated by some Lisa what’s-her-name talking about the supposedly miracle results of the brand “such-and-such” found on the web!

Well, I’m off. See you soon, Dad.

It seems that a prophet is not without honor, save in his own country!