How does olive seed chemistry, health benefits and action mechanisms compare to its fruit oil? A comprehensive review for valorization purposes and maximizing its health benefits

Olive (Olea europaea) has economical value in the Mediterranean region being used for the production of olive oil which represents a significant economic asset. The vision for olive oil byproducts is being dramatically changed from industrial waste products and sources of pollution to significantly important byproducts considering their beneficial effects and potential applications. Olive seed is a major byproduct of the olive oil industry that has gained increasing attention for its health benefits and rich phytochemical composition. Seed presents a potential source of components including dietary fiber (45%), lipids (35%), and proteins (15%). With regards to secondary metabolites in olive seed, hydroxytyrosol and tyrosol are the main phenolics. Among olive seed health benefits, antioxidant, antimicrobial, and anti-inflammatory activities are the most prominent. In addition, in vitro and in vivo studies revealed seeds’ potential cytotoxic effects, antidiabetic, antihyperlipidemic, liver and kidney protective effects. This comprehensive review summarizes the reported health benefits of olive seeds including antioxidant, anti-inflammatory, antihyperlipidemic, antitumor, antidiabetic, and antimicrobial activities, underlying action mechanisms, and in context to its phytochemical composition. Results are presented from different cultivars and origins for the first time in literature and in comparison, with the well-reported health benefits of olive oil or its pomace. Further, attempts to improve olive seed functionalization and industrial applications is presented for the first time.