One of the factors that is believed to contribute to Japanese longevity is their dietary life, which is unique and distinct from Westerners. However, there has been no study that examined whether Japanese food in itself is effective for health maintenance. Therefore, we investigated in rats whether Japanese food is beneficial to health maintenance compared with American food. As a result, we revealed that modern Japanese food is useful for health maintenance compared with modern American food. We subsequently investigated the health benefits of Japanese food from different eras. The menus of Japanese foods from 4 different years, 2005, 1990, 1975 and 1960 were prepared, cooked, and powderized. Each of the Japanese foods was provided to mice. We found that the Japanese food from 1975 exhibited health benefits with respect to the stages of growth, adolescence, maturity and old age. Furthermore, we focused on fish oil, which is one of the beneficial ingredients of Japanese food, and investigated the effect of its long-term intake on lifespan in mice. Surprisingly, long-term intake of large amounts of fish oil shortened the lifespan of these mice. By contrast, intake of small amounts of fish oil with antioxidants extended the lifespan. Moreover, while intake of large amounts of fish oil also shortened the lifespan of Caenorhabditis elegans (C. elegans), intake of small amounts of fish oil extended the lifespan. Thus, it was suggested that even when foods have been reported to have health benefits, ingestion of large amounts of individual foods is undesirable for health maintenance.