Blog entry 3: Probiotics - does it bring anything?

The last blog post contained the determination of the gut microbiome and its structure, as well as the assessment of its functions in the human body. This post is engaged with the influences of consumed probiotic bacteria on the gut microbiome and the human health.

In general, probiotics are described as living microorganisms, which have a beneficial impact to the human health when consumed in certain numbers (1). But can this benefit be scientifically proven?

Effects of probiotics on human health

It has been widely researched how the nutrition influences and changes the human gut microbiome. That the diet directly alters the composition of the microbiome has been proven by many different studies. Diet-induced obesity for example can be directly linked to the way the gut microbiome is structured. (2) The idea to deliberately wanting to improve the own health through diet seems comprehensible. Probiotics are one example for dietary supplements that should be constitutional when consumed regularly.

Probiotics (usually bacteria) survive the passage through the acid environment of the stomach and alter the microbial balance in the gut. They are known to crowd out potentially pathogenic bacteria that are already present. After that, the probiotic bacteria create an unfavourable environment for said pathogenic organisms. (3)

The most commonly used probiotics are Lactobacillus and Bifidobacterium. Although those are only two examples of a great number of species that can be used as probiotics. (4)

Some of the said beneficial effects of probiotic consumption include: (3)

• the increase of nutrient availability in fermented food and even the production of nutrients in the gut
• the reduction of symptoms from lactose intolerance
• the reduction of the severity of intestinal infections
• the reduction of blood cholesterol concentrations
• some protection against bowel cancer when probiotics are consumed long-term

Figure 1: Beneficial effects of probiotics on human health (4)

Probiotics in commercial use 

Despite many apparent advantages that come with the consumption of probiotics, it has to be considered that the knowledge of the gut microbiome is still very limited and therefore, the effects of probiotics cannot be distinctly defined. It is still unclear which parts of the microbial communities in our gut influence our health and how exactly they do so. (5)

In the end, even if probiotics have a positive influence on the gut microbiome, it has to be kept in mind that said bacteria are easily killed or destroyed during the process of making them available for consumers as dietary supplements (6). So even if probiotics are advertised on products in commercial use, the bacteria contained may not be alive anymore and won’t be beneficial for the gut microbiome. It would be important to know for the consumer how the product was processed and whether the bacteria are still alive when the product is consumed. However, Technologies in food productions are getting more and more advanced and it can be supposed that in the future there will be more and more possibilities in producing sensitive food with live probiotic bacteria.

References

(1) FAO/WHO. (2002). Guidelines for evaluation of probiotics in food. Report of a Joint FAO/WHO Working Group on Drafting Guidelines for the Evaluation of Probiotics in Food. Retrieved from http://www.who.int/foodsafety/fs_management/en/probiotic_guidelines.pdf

(2) Robinson, C. J., Bohannan, B. J. M., & Young, V. B. (2010). From Structure to Function: the Ecology of Host-Associated Microbial Communities. Microbiology and Molecular Biology Reviews, 74(3), 453–476. https://doi.org/10.1128/MMBR.00014-10

(3) Geoffrey P. Webb. (2006). Dietary Supplements & Functional Foods. Oxford: Blackwell.

(4) Lee, Y.-K., & Salminen, S. (Eds.). (2009). Handbook of probiotics and prebiotics (2nd ed). Hoboken, N.J: John Wiley & Sons. Retrieved from http://dx.doi.org/10.1002/9780470432624

(5) Nagpal, R., Kumar, A., Kumar, M., Behare, P. V., Jain, S., & Yadav, H. (2012). Probiotics, their health benefits and applications for developing healthier foods: a review. FEMS Microbiology Letters, 334(1), 1–15. https://doi.org/10.1111/j.1574-6968.2012.02593.x

(6) Watson, R. R., & Preedy, V. R. (2010). Bioactive Foods in Promoting Health: Probiotics and Prebiotics. Academic Press.