An article published by BBC just a few days ago confused the probiotic community. Based on a scientific publication from a group of scientists in Israel (Weizman Institute), BBC used the headline Probiotics labelled 'quite useless'. This statement has to be taken with caution. In the work, published by Zmora and colleagues, 25 healthy volunteers have taken a cocktail of 11 common bacteria over a one month time period. The researchers took samples of the stomach, small and large intestines. In one half of the volunteers, the bacteria just passed through the intestinal tract, in the other half, the bacteria stayed in the gut for a while until they were outcrowded by the existing microbiome. This outcome is not surprising at all. It does not mean that probiotics are useless though …
We know that a healthy microbiome occupies the space in the gut, preventing the colonisation of foreign bacteria. In people with a healthy gut microbiome, probiotics mostly only have a prophylactic effect (when taking antibiotics or when catching some bad bugs on a trip to a foreign country). A beneficial effect was seen in most cases, when it dealt with a disturbed microbiome.
Probiotics still doing their job
Another point is that probiotics, even though they only stay for a little bit in our gut, are still doing their job while passing our intestines.
On top of that, it is crucial to take the right probiotic. It might be true that probiotic products out of the supermarket shelf might not have the beneficial health effect. The bacteria inside the product always have to be well characterized (exact strain has to be mentioned in the ingredients list) and the recommended dose of each bacterium must be given. Never use products which lack that kind of information!
The BBC article also mentions that probiotics may even delay the recovery of the microbiome after antibiotics administration. This has been documented in a further publication from the Weizmann Institute. The scientists used the same mixture of probiotic strains as in the publication before. It seems that although the strains did not colonize in half of the volunteers (see above) the bacteria still had an impact on the host’s microbiome when antibiotics were administered. This result is of course alarming, so far we did not see any negative side effects with probiotics. The probiotic mixture used in this study includes a range of Lactobacilli, Lactococci, Bifidobacteria and Streptococci – the typical strains used in probiotic products. However, the bacterial count of each single species and the exact strain were not mentioned – that would be crucial. Since there’s a lot of evidence out there which shows that probiotics may prevent antibiotic associated diarrhea, the selection of the right strains seems to be more crucial than ever, looking at these results.
The best strains
A group from the Netherlands just recently published a very nice review which analyses all available clinical studies with probiotics, regarding the ability to reduce or prevent antibiotic-associated diarrhea (AAD) and concluded that the following strains were the best recommendations for this indication:
- Lactobacillus rhamnosus GG (daily dose 2 x 109cfu)
- A mixture of Lactobacillus rhamnosus GG, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-1
An analysis of clinical studies with probiotic products available in the Netherlands revealed that none of the available dairy products showed a significant effect on the reduction of AAD and only one food supplement which contained Lactobacillus rhamnosus GG (minimal dose: 2 billion CFU) showed a positive effect on AAD in at least three clinical studies.
Choose probiotics with care
Taken together, these new scientific outcomes again prove that a careful selection of the right probiotic is the key to a health benefit with probiotics. Furthermore probiotics won’t necessarily show a positive effect on people with a healthy gut microbiome, however, this does not mean that probiotics as such are useless. For the consumer and physicians it is of elementary importance to be informed about how to use which probiotic. There's still a lot of work ahead of us! We're doing our best.
Save your microbiome!