In this interview, Francisco Guarner Aguilar, a clinical gastroenterologist based in Barcelona, reviewed some of the most significant probiotic-related papers published in recent years, spanning basic research, clinical trials, and population-based studies. Among the highlights was a Nature study addressing the challenge of cultivating Faecalibacterium prausnitzii, one of the main butyrate-producing bacteria in Western populations and a promising but difficult-to-develop next-generation probiotic because of its extreme oxygen sensitivity. 

The study showed that co-culturing F. prausnitzii with Desulfovibrio piger, a sulfate-reducing bacterium that helps reduce oxygen exposure, may offer a practical strategy to increase butyrate-producing capacity in individuals with low baseline levels of F. prausnitzii. 

The interview also discussed a placebo-controlled trial of Lacticaseibacillus rhamnosus GG (LGG) during the COVID-19 pandemic, in which post-exposure administration in household settings was associated with milder symptoms and a lower rate of infection. 

Finally, Guarner examined observational data from the US NHANES survey suggesting that the use of probiotic or prebiotic supplements may be associated with reduced long-term mortality, including cardiovascular- and cancer-related mortality. Together, these studies illustrate the breadth of current probiotic research and highlight both the promise of specific strains and the need for continued clinical and epidemiological validation.