Hydroxycinnamic acids on gut microbiota and health

Hydroxycinnamic acids (HCAs) are a major class of phenolic acids with the characteristic phenylpropanoid C6 -C3 backbone. Its typically conjugated status with plant cell wall components and liberation by limited enzymes might be the reason for its neglect by researchers compared to flavonoid-type polyphenols. The polyphenol-gut microbiota interactions and their impact on human health have captured the interest of researchers recently. In addition, there has been a significant progress over the past few years in understanding the gut microbiota-modulating effect of HCA using animal model studies. This review discusses the metabolism of HCA in the digestive tract, HCA-gut microbiota interactions, and its link to colorectal cancer, inflammatory bowel diseases, mental-cognitive impairments, nonalcoholic liver disease, and obesity. The effects of food matrix and processing technologies on HCA bioavailability and HCA-gut microbiota interactions, and HCA safety concerns are also featured in this review. This paper has provided an in-depth insight on HCA-gut microbiota relationship and identified the current literature gaps for future research.