Antioxidant micronutrients such as vitamins and carotenoids exist in abundance in fruits and vegetables and are known to contribute to the body’s defense against reactive oxygen species. Numerous recent epidemiologic studies have demonstrated that a high dietary consumption of fruits and vegetables rich in carotenoids or producing high serum carotenoid concentrations results in a decreased risk for certain cancers, diabetes, and cardiovascular disease. These epidemiologic studies have suggested that antioxidant carotenoids exert a protective effect against several lifestyle-related diseases. Beta-cryptoxanthin is a carotenoid pigment particularly found in Japanese mandarin ( Citrus unshiu Marc.) fruit, which is heavily produced in Japan. Our nutritional epidemiologic survey, the Mikkabi Study, utilized data derived from health examinations involving inhabitants of the town of Mikkabi in Shizuoka, Japan. In this survey, we measured serum beta-cryptoxanthin as a specific bio-marker to estimate the consumption of Japanese mandarin fruit. The cross-sectional analyses of the Mikkabi Study indicated inverse associations between serum β -cryptoxanthin and the risk for atherosclerosis, insulin resistance, liver dysfunction, metabolic syndrome, low bone mineral density and oxidative stress. In this chapter, recent epidemiologic studies of the association between serum beta-cryptoxanthin and the risk for several lifestyle-related diseases are reviewed.