Proanthocyanidins in grape seeds: An updated review of their health benefits and potential uses in the food industry

Grape seeds are rich sources of proanthocyanidins, which comprise polyhydroxyflavan oligomers or polymers. The beneficial health properties of grape seed proanthocyanidins are attributed to their conjugated and colonic metabolites. There is potential for a two-way relationship between the gut microbiota and grape seed proanthocyanidin. In particular, numerous in vitro and in vivo studies have demonstrated that grape seed proanthocyanidins appear to exert pharmacological effects. These include anti-oxidant, anti-microbial, anti-obesity, anti-diabetic, anti-neurodegenerative, anti-osteoarthritis, anti-cancer, and cardio- and eye-protective properties. In this review, it is aimed to summarize the current literature regarding grape seed proanthocyanidins, focusing on the recently proposed mechanisms of action from clinical trials considered to underlie pharmacological and disease-preventing properties, along with their bioavailability, toxicology, and safety with regard to potential utilization in the food industry.