Polyphenols are a class of compounds that are abundant in plants, particularly in their seeds, leaves, peels and roots. In the 1990s, several epidemiological studies reported an association between polyphenol intake and atherosclerotic diseases. Comprehensive databases of polyphenol contents in foods were subsequently published, and studies estimating polyphenol intake began to be conducted in various countries. This chapter first discusses efforts to estimate polyphenol intake, followed by the association between polyphenol intake and the risk of cardiovascular disease (CVD) and mortality.