Healthy foods such as beans, mushrooms, vegetables, and seafood and healthy dietary patterns such as the Mediterranean diet and Japanese food have higher concentrations of polyamines (spermine and spermidine). The continuous intake of high-polyamine foods has been shown to increase whole blood polyamine levels in mice and humans. In addition, high-polyamine chow inhibited aging-associated pathological changes in Jc1:ICR male mice and extended their lifespan. Aging is accompanied by decreased DNA methyltransferase activities, increased proinflammatory status, and enhanced abnormal gene methylation status, which is considered to be part of the pathogenesis of aging-associated diseases. In vitro and in vivo experiments have shown that polyamine supplementation reversed such changes induced by aging and polyamine-deficiency. In addition, polyamines have many biological activities that may contribute to the inhibition of lifestyle-related diseases such as diabetes, hyperlipemia, and arteriosclerosis. The possible role of dietary polyamines in human health is discussed.