You’ll have reason to smile the next time you dine on Japanese food. The research department at Ogawa & Company in Japan found that wasabi helps prevent cavities. The superhot green paste made from Japanese horseradish (Wasabia japonica) is best known as a condiment for sushi. The same compounds (isothiocyanates) that produce its spicy-hot taste inhibit tooth decay, making it difficult for bacteria to stick to teeth and bone. Wasabi also strongly inhibits growth of bacteria and fungi responsible for food poisoning. A Japanese study from the Nagoya University Graduate School of Bioagricultural Sciences found that horseradish has anticancer properties and enhances glutathione S-transferase activity, which is involved in liver detoxification. Other compounds known to deter dental cavities are antibacterial tannins in grapes, polyphenols in green tea (Camellia sinensis) and anacardic acid in cashews.
Source: Morimitsu, Y., et al. “Antiplatelet and anticancer isothiocyanates in Japanese domestic horseradish, wasabi.” Biofactors 2000, 13(1 - 4): 271–276.