Polyphenols in cancer prevention: New insights (Review)

A huge volume of literature data suggests that a diet rich in fruits and vegetables, mostly due to the contribution of natural polyphenols, could reduce the incidence of specific cancers. Resveratrol, epigallocatechin gallate and curcumin are among the most extensively studied polyphenols: The majority of the effects attributed to these compounds are linked to their antioxidant and anti‑inflammatory properties. The multiple mechanisms involved include the modulation of molecular events and signaling pathways associated with cell survival, proliferation, differentiation, migration, angiogenesis, hormonal activities, detoxification enzymes and immune responses. Notwithstanding their promising role in cancer prevention and treatment, polyphenols often have a poor bioavailability when administered as pure active principles, representing an important limit to their use. However, the bioavailability and thus the efficacy of these compounds can be improved by their administration in combination with other phytochemicals, with anticancer drugs or in polyphenol‑loaded nanotechnology‑based delivery systems. The possibility of combining conventional drugs with polyphenols offers very valuable advantages, such as the building of more efficient anticancer therapies with less side‑effects on the health of patients. The present review focuses on current knowledge regarding the interactions between natural polyphenols and cancer development in order to gain a clearer comprehension of the potential mechanisms through which individual foods and food components may be exploited to reduce cancer risk.