Impact of Probiotics on Gut Microbiome Bifidobacterium Relative Abundance: First Do No Harm
The relative abundance and normalized read count of Bifidobacteria were significantly lower in the microbiome of subjects who took unregulated probiotics (n=15) than in the microbiomes of both those who took regulated probiotics (n=12, P=0.0002) and no probiotics (n=13, P=0.0483) (0.18 vs. 9.59 vs. 5.66 relative abundance).
“Unregulated” probiotics were defined as over-the-counter branded pills that are not regulated by the FDA. Probiotics were classified as “Regulated” are FDA approved.
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More on sketchy probiotic products:
There is a substantial body of “evidence” advocating the benefits of probiotic supplements. However, the quality of evidence, as well as the quality of the production of probiotic supplements are matters of concern. In a systematic review of the effects of Lactobacillus casei or Bifidobacterium lactis on a healthy population, 16 studies were evaluated to assess health benefit claims [8]. Of 47 studies listed on the corporate website, all were funded by the company and only 12 overlapped with those meeting inclusion criteria for the systematic review. Only seven of the 12 demonstrated some positive effect following consumption of probiotic-enriched milk products. And none of these seven actually demonstrated a clinical benefit to use of the product; rather, they extrapolated from laboratory values. The three pertaining to L. casei received a recommendation grade of D for relying primarily on circumstantial evidence and opinion. In contrast, the four pertaining to B. lactis were of sufficient scientific rigor to merit a recommendation grade of [9,10]. These results suggest that there may be inadequate scientific evidence to support the health claims made for many probiotic products.
Looks like they typoed and forgot to include the B. lactis recommendation grade but you can see the relevant study here
continuing:
The quality of probiotics is also of concern, largely due to the absence of supplement regulation. In a national survey of commercial probiotic food supplements in Italy, of 25 samples that claimed B. bifidum was present, none contained the live bacterium and the non-viable bacterium was only sporadically present [11]. More importantly, some of these supplements contained toxin-producing species of bacteria including Bacillus cereus. Another study that evaluated 16 probiotic products found the contents of only one brand to match its label claims. And even within that particular brand, inter- and intra-lot variation was noted [12]. In many cases the products contained little or no viable bacteria. A third study involving 26 probiotic products found instances of misidentification of the bacteria at both the species (27 incorrectly identified) and genus levels (19 incorrectly identified) [13,14]. This misidentification is clinically significant. As quoted by Rijkers et al in 2011, “Stig Bengmark has made this very clear in his statement that the (genetic) difference between one probiotic bacterium and the other is larger than the difference between a man and a goldfish.” This is illustrated by a study which compared the activity of two different Lactobacillus strains (Lactobacillus salivarius CECT5713 and Lactobacillus fermentum CECT5716) in mice. Despite the similarities between the strains, L. fermentum was found to be immunostimulatory, whereas L. salivarius was found to have an anti-inflammatory response [15]. When dietary supplement production facilities were inspected in 2019, over half( 305/598) were issued Form 483 for violations of manufacturing standards and safety. The most commonly cited violation category–accounting for 25% of violations–was failure to adequately describe the final product, including identity, purity, and strength. Other violations included an absence of written quality control procedures, failure to follow written procedures, and incomplete batch records [16]. Poor quality control was identified as the main factor leading to noncompliance. Given the staggering lack of quality control checks in the probiotic industry, choosing an appropriate probiotic supplement is challenging.
