Probiotics may help ease COVID-19 symptoms and slow their onset in unvaccinated adults, according to a study published in Clinical Nutrition.
The researchers noted that even before the emergence of COVID-19 there was solid evidence linking probiotics to protection against respiratory infections. In this study, data were drawn from 182 unvaccinated individuals who had been in contact with people carrying the virus. Half received a probiotic containing lactobacillus, while the other half received a dummy tablet with no active ingredient. Neither participants nor study staff knew who received the real treatment, a design that minimizes placebo effects and biases in reporting and assessment.
Those treated with the probiotic were about 60% less likely to develop COVID symptoms in the early days following exposure compared with the placebo group, with 26% of the probiotic group becoming infected versus 43% in the placebo group.
Earlier research indicates that probiotics can enhance immune defense and may increase the effectiveness of vaccines such as the flu shot. They have been associated with boosting the population of regulatory T cells and with lowering levels of pro inflammatory cytokines, which can influence immune responses and inflammation.
According to the study authors, despite the small participant pool, the findings support the idea that common microbes may play a meaningful role in countering COVID-19 and potentially other emerging infectious diseases. The researchers emphasized that this could be especially relevant for countries with limited vaccine access or uptake, and for communities in parts of the United States where booster availability may be uneven.
Earlier work also cautioned that some remedies marketed for colds could pose risks for individuals with hypertension or other health conditions, underscoring the importance of consulting healthcare professionals before beginning any new supplement or regimen.