Table 1.

Probiotics and COVID-19.

	Mechanism of action and potential benefits	Potential harms or adverse reactions	Association with COVID-19 infection	Ongoing registered clinical trials related to COVID-19
Probiotics	Prevents gut dysbiosis and intestinal inflammation Contributes to reduction in systemic inflammatory response Improves outcomes in upper respiratory and lower respiratory infection Modulates antiviral activity via stimulation of native immunity in the gut	May theoretically cause the following side effects in at risk patients with weakened immune system, gut dysbiosis and/or impaired intestinal barrier.	Downregulates ACE2 receptors, altering gut microbiota Upregulates pro-inflammatory chemokines and cytokines, including fecal calprotectin and serum interleukin-6 Microbial dysbiosis with decreased Lactobacillus and Bifidobacterium species in patients with COVID-19	There are 9 ongoing registered clinical trials related to probiotics and COVID19 on clinicaltrials.gov