| CFU | Colony-forming unit |
| LAB | Lactic acid bacteria |
| QoL | Quality of life |
| RCT | Randomized clinical trial |
| RDBPCT | Randomized, double-blind, placebo-controlled trial |
| SCFAs | Short-chain fatty acids |
| URTIs | Upper respiratory tract infections |
| CFU | Colony-forming unit |
| LAB | Lactic acid bacteria |
| QoL | Quality of life |
| RCT | Randomized clinical trial |
| RDBPCT | Randomized, double-blind, placebo-controlled trial |
| SCFAs | Short-chain fatty acids |
| URTIs | Upper respiratory tract infections |