Researchers at the Hospital General Manuel Gea Gonzalez in Mexico City have reported results on a study which investigated the impact that four probiotic strains might have on rate of remission in outpatients who were infected with SARS-CoV-2, the virus that causes COVID-19.
 
The study investigated the effects of a one-a-day probiotic or placebo capsule over a 30-day period in confirmed adult COVID-19 patients who had mild symptoms and were not hospitalized. According to the authors of the placebo-controlled, double-blinded clinical trial which randomized 300 patients between the ages of 18 and 60 with PCR-confirmed COVID-19 and mild symptoms, four specific probiotic strains showed significant results on remission rate, duration of symptoms, and viral load, as measured by RT-PCR. No ICU admissions were observed during the study period, and there were no adverse events associated with the probiotics strain blend.
 
Currently, detailed efficacy and safety results are being submitted for peer review, which will address remission rate, as measured by both the absence of COVID-19 symptoms and a negative RT-PCR test, a reduction in the number of symptomatic patients with COVID-19, a reduction in the duration of specific symptoms, a reduced viral load in nasopharyngeal swabs, and increased specific IgG and IgM levels against SARS-CoV-2.
 
The Gut-Lung Axis
The working hypothesis behind the study was that probiotic supplementation may reduce remission rates via what is commonly defined as the gut-lung axis, an umbrella term for the cross-talk between intestinal and pulmonary tissues which is mediated by both the microbiome and immune cells. Studies involving other respiratory diseases have provided evidence that the gut-lung axis may serve as a mechanism by which probiotics could support respiratory health.
 
With 75% of the immune system being associated with gut cells, the gut microbiota has been evidenced to be significantly involved in regulating the development and function of the immune system, the authors of the study said. Further, they state that one in three patients afflicted with COVID-19 present dysbiosis (an imbalance of gut bacteria populations induced by environmental factors), and gastrointestinal symptoms are linked to an increased severity of the disease.
 
“The preliminary results of this clinical trial are encouraging and we are extremely excited to have been a part of such timely research,” lead investigator Pedro Gutierrez Castrellon, MD, said. “Further research is needed to corroborate and explore additional benefits, however it’s important to note that probiotics are well known for their health benefits on the host, when administered in adequate amounts. As stated by the WHO [World Health Organization], they require well-designed clinical trials to be considered as such, and their benefits are strictly strain-specific, therefore positive evidence in a clinical trial for a particular health condition, efficacy cannot be extrapolated or extended to other strains without clinical evidence.”
 
The specific probiotic strains used in this study were L. Plantarum KABP-033, L. Plantarum KABP-022, L. Plantarum KABP-023, P. Acidilactici KABP-021, all of which were supplied by AB-Biotics, a subsidiary of Kaneka Corporation.