Intestinal Exposure to Food-Derived Protease Inhibitors: Digestion Physiology- and Gut Health-Related Effects

Plant-derived protease inhibitors (PI), such as Bowman-Birk inhibitors and Kunitz-type inhibitors, have been suggested to negatively affect dietary protein digestion by blocking the activity of trypsin and chymotrypsin in the human gastrointestinal system. In addition, some PIs may possess proinflammatory activities. However, there is also scientific evidence on some beneficial effects of PIs, for example, gut-related anti-inflammatory and chemopreventive activities in vitro and in vivo. Some PIs are sensitive to processing and digestion; thus, their survival is an important aspect when considering their positive and negative bioactivities. The aim of this review was to evaluate the relevance of PIs in protein digestion in humans and to discuss the potential of PIs from whole foods and as purified compounds in decreasing symptoms of bowel-related conditions. Based on the reviewed literature, we concluded that while the complex interactions affecting plant protein digestibility and bioavailability remain unclear, PI supplements could be considered for targeted purposes to mitigate inflammation and gastric pain.