Polyphenols, secondary metabolites of plants, have gained significant attention for their potential health benefits as dietary antioxidants. Epidemiological studies and meta-analyses suggest that long-term consumption of diets rich in plant polyphenols offers protection against various chronic diseases, including cancer, cardiovascular diseases, diabetes, osteoporosis, and neurodegenerative diseases. Polyphenols are found in fruits, vegetables, cereals, and beverages, with high concentrations in red wine, tea, and coffee. They are classified into several groups, including phenolic acids, flavonoids, stilbenes, and lignans, each with unique chemical structures and biological activities. The bioavailability of polyphenols is influenced by their chemical structure, dietary sources, and processing methods. Polyphenols are absorbed through the gastrointestinal tract, undergo metabolic modifications, and are distributed to tissues where they exert their biological effects. Their antioxidant properties help neutralize reactive oxygen/nitrogen species, reducing oxidative stress and protecting cellular components from damage. Polyphenols have been shown to have cardioprotective effects by inhibiting LDL oxidation, improving endothelial function, and reducing platelet aggregation. They also exhibit anti-cancer properties by inducing apoptosis, inhibiting cell proliferation, and modulating the immune system. Additionally, polyphenols can help manage diabetes by affecting glucose metabolism and reducing oxidative stress. Their anti-aging effects are attributed to their antioxidant and anti-inflammatory properties, which can delay the onset of age-related diseases. Overall, the biological effects of polyphenols on human health are multifaceted, and their consumption is increasingly recognized as a potential strategy for preventing chronic diseases. However, further research is needed to fully understand the mechanisms and optimal intake levels of polyphenols for therapeutic benefits.Polyphenols, secondary metabolites of plants, have gained significant attention for their potential health benefits as dietary antioxidants. Epidemiological studies and meta-analyses suggest that long-term consumption of diets rich in plant polyphenols offers protection against various chronic diseases, including cancer, cardiovascular diseases, diabetes, osteoporosis, and neurodegenerative diseases. Polyphenols are found in fruits, vegetables, cereals, and beverages, with high concentrations in red wine, tea, and coffee. They are classified into several groups, including phenolic acids, flavonoids, stilbenes, and lignans, each with unique chemical structures and biological activities. The bioavailability of polyphenols is influenced by their chemical structure, dietary sources, and processing methods. Polyphenols are absorbed through the gastrointestinal tract, undergo metabolic modifications, and are distributed to tissues where they exert their biological effects. Their antioxidant properties help neutralize reactive oxygen/nitrogen species, reducing oxidative stress and protecting cellular components from damage. Polyphenols have been shown to have cardioprotective effects by inhibiting LDL oxidation, improving endothelial function, and reducing platelet aggregation. They also exhibit anti-cancer properties by inducing apoptosis, inhibiting cell proliferation, and modulating the immune system. Additionally, polyphenols can help manage diabetes by affecting glucose metabolism and reducing oxidative stress. Their anti-aging effects are attributed to their antioxidant and anti-inflammatory properties, which can delay the onset of age-related diseases. Overall, the biological effects of polyphenols on human health are multifaceted, and their consumption is increasingly recognized as a potential strategy for preventing chronic diseases. However, further research is needed to fully understand the mechanisms and optimal intake levels of polyphenols for therapeutic benefits.