Probiota 2024: Exploring Probiotic Efficacy Beyond CFUs

A couple of weeks ago we attended Probiota 2024 in Milan, a global meeting to discuss the science and the state of the probiotics market.

The conference had many interesting scientific discussions, but what really piqued our interest were the insights shared by professionals in the marketing sector. One key takeaway stood out: the importance customers place on the number of Colony Forming Units (CFUs) when choosing  products containing probiotics, as opposed to seeking out specific bacterial strains.

CFUs, as a measure of live bacteria, have become a focal point for consumers navigating the growing probiotic market. It's fascinating to note how billions of CFUs prominently advertised on product labels sway purchasing decisions. There could be two reasons for this preference. Either in the absence of any other information, consumers find the CFUs a convenient metric to compare products for efficacy. Or they have found from experience that CFUs do in fact correlate with product effectiveness. 

Research suggests that probiotic bacteria from supplements do not permanently colonise the gut1,2,3.Therefore, higher CFU counts in products may offer a better chance for them to exert a positive effect, possibly explaining why customers opt for products with higher CFUs.

While the emphasis on CFUs in probiotic products is evident, it also underscored a broader issue: the general lack of consumer awareness regarding the distinctions between different bacterial strains. Despite the varied impacts of these strains, as demonstrated in clinical trials, our understanding of their biology and the mechanisms of interactions with the host remains incomplete. If research can provide clear answers to these questions, consumers may be empowered to select strains tailored to their needs rather than relying solely on CFU counts as the  determinant of product efficacy.

Our discussions with industry peers during the event not only shed light on consumer preferences but also sparked considerable interest in the innovative assays available at Magnitude Biosciences. Utilising C. elegans, a tiny nematode worm, which can be cultured in conjunction with specific bacterial strains, these assays offer insights into specific health-related outcomes of exposure to probiotics. The worm can be used to measure how probiotics improve gut health, muscle health, alter metabolic endpoints like fat accumulation, and change animal behaviour. Because the worm ages in just a few weeks, it can be determined if probiotics can slow the decline in these functions with age. Once an effect is found, the genetics of C. elegans or the bacterial strains can be used to understand the mechanisms of action. 

At the last Probiota, there was a compelling talk by Alex Parker, from Montreal, highlighting the ability of a specific probiotic strain to halt neurodegeneration in ALS models for worms4. And genetics was used to establish a mechanism - an alternative pathway of fatty acid metabolism that was fed by products of the particular bacterial strain. They were successfully able to recreate the results in a mouse model of ALS, which allowed them to advance to human clinical trials that are ongoing. This groundbreaking research shows that C. elegans can be used to identify strains with specific functions and unravel mechanisms relevant to human biology. Probiota 2024 was a testament to the dynamism of the probiotics industry, with many captivating conversations, visionary individuals, and innovative products, so thank you to all those that I had the chance to speak with. 

As we navigate the ever-evolving landscape of probiotics and supplements, it's crucial to acknowledge the multifaceted nature of consumer decision-making. While CFUs serve as a valuable metric, understanding the underlying mechanisms of probiotic action opens doors to informed choices and enhanced consumer outcomes.


  1. Eliaz, Isaac. ‘The Failure of Probiotics—and the Strategy of Microbiome Synergy’. Integrative Medicine: A Clinician’s Journal 19, no. 3 (June 2020): 8–10.
  2. Han, Shengyi, Yanmeng Lu, Jiaojiao Xie, Yiqiu Fei, Guiwen Zheng, Ziyuan Wang, Jie Liu, et al. ‘Probiotic Gastrointestinal Transit and Colonization After Oral Administration: A Long Journey’. Frontiers in Cellular and Infection Microbiology 11 (2021).
  3. Support, Administration and Research. ‘Do Probiotics Have an Effect on Healthy Adults? It’s Too Early to Tell’. University of Copenhagen, 23 May 2016.
  4. Labarre, Audrey, Ericka Guitard, Gilles Tossing, Anik Forest, Eric Bareke, Marjorie Labrecque, Martine Tétreault, Matthieu Ruiz, and J. Alex Parker. ‘Fatty Acids Derived from the Probiotic Lacticaseibacillus Rhamnosus HA-114 Suppress Age-Dependent Neurodegeneration’. Communications Biology 5, no. 1 (7 December 2022): 1–19.

Get regular updates in your inbox

Sign up to our newsletter today, to get access to the latest company and industry news