Phenolic acids, such as caffeic acid, ferulic acid, and chlorogenic acid, are a class of plant-derived compounds found in various fruits, vegetables, and whole grains. There is some scientific evidence suggesting that phenolic acids may offer support to the respiratory system, mainly due to their antioxidant, anti-inflammatory, and antimicrobial properties. Preclinical studies (in vitro and animal models) have shown that phenolic acids can reduce oxidative stress and suppress inflammatory pathways in lung tissue, which are factors involved in respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and respiratory infections.

For example, caffeic acid has been reported to inhibit inflammatory mediators (such as TNF-α and IL-6) in airway epithelial cells, while ferulic acid has demonstrated protective effects against lung injury in animal models exposed to toxins or particulate matter. Some studies have also noted that phenolic acids may enhance the activity of endogenous antioxidant enzymes in lung tissue, potentially mitigating cellular damage caused by pollutants or infections.

However, robust clinical trials in humans are lacking, and the available evidence is mostly limited to laboratory and animal studies. While these findings are promising, more research is needed to confirm the efficacy and safety of phenolic acids for respiratory support in humans. Therefore, the current scientific evidence is preliminary and does not yet justify strong recommendations for their use in respiratory health.