Followed by cardiovascular disease, cancer is the second biggest cause of deaths in the world, with 20% of all mortality. Epidemiological studies around the globe document approximately 30% of all cancer deaths relate to diet and life style. Genetic susceptibility is also a significant risk factor (Eddy, 1986). Dietary modification seems to be one of the most common sense and realistic approach can make a significant reduction in cancer risk (Milner, 1994). Diet induced activation and bolstering the immune system could have significant impact on cancer prevention (Young, 1997a). Complementary and alternative therapies have become very common therapeutic approach in cancer prevention and are being taught and practiced in World’s academic and clinical institutions. Functional foods (FF) fall under this category and can benefit in three different ways-first is maintaining and strengthening immune system, second is acting upon the tumor directly, and third is that synergistic use may reduce drug toxicity and improve quality of life. Some new and innovative nutritional supplements will be discussed, e.g. dietary RNA, AHCC, and Oligonol from natural sources. Discussed also will be the definition, applications and regulatory issues of FF.