Sarkar - Nutraceuticals and Cancer

Department of Medicine, David Geffen School of Medicine, UCLA Center for Excellence in Pancreatic Diseases, University of California, Los Angeles, CA 90095-1786, USA

AICR

CAM

CARDS

CDC

DGA

DSHEA

FIM

NCI

USDA

USFDA

USDHHS

NIH

Cancer is a chronic disease of the genome that is influenced at many stages of carcinogenesis, promotion and progression by environmental factors; thus the cancer metabolic phenotype is the result of the interaction between the genome and environmental factors. Perhaps the strongest environmental component is diet and related lifestyle factors. In fact, it has been estimated that some 35% of all cancer deaths are caused by diet, although depending on cancer site, the estimates of cancer deaths attributable to diet can range from 10 to 70% (World Cancer Research Fund ).

The distribution of cancer incidence and mortality rates varies geographically due to the influences of various environmental and cultural factors. In economically developing countries such as those in Asia, Africa, and Latin America, cancers of the upper aerodigestive tract, stomach, liver, and cervix are common, but in developed countries, such as those in Europe and North America, colorectal and hormone-related (breast, ovary, endometrium, and prostate) cancers predominate (World Cancer Research Fund ).

There is no clear definition for the term nutraceutical. The first definition came from the Foundation for Innovation in Medicine (FIM): A nutraceutical is any substance that is a food or a part of a food and provides medical or health benefits, including the prevention and treatment of disease (DeFelice ). The distinctions between these categories are largely driven by marketing, but some do have regulatory definitions.

In the U.S., dietary supplements are defined in the Dietary Supplement Health and Education Act (DSHEA) of 1994 as a product taken by mouth that includes a dietary ingredient intended to supplement the diet (USFDA ).

The definitions of functional foods and medicinal foods are not distinct and are still evolving; currently the FDA has no regulatory authority over functional foods. In fact, Japan is the only country that has a regulatory framework for functional foods, known there as Foods for Specified Health Use (Hasler and Brown ).

The term phytochemicals applies to a wide variety of plant-derived compounds produced by plants which can be used as nutraceuticals. Bioactive phytochemicals possess anticarcinogenic, antimutagenic, antiinflammatory, and antioxidant properties. There may be as many as 100,000 different compounds found in a variety of fruits, vegetables, and other plants, including carotenoids, flavonoids, organosulfur compounds, isothiocyanates, indoles, monoterpenes, phenolic acids, and chlorophyll; the activity of many of these nutraceuticals on cancer prevention and treatment are discussed comprehensively in subsequent chapters (Harris and Go ). This study used the Phenol-Explorer database, which contains data on 502 polyphenols in 452 foods, to find that a total of 337 polyphenols were consumed in a large group of French adults. This was one of the first studies to evaluate the comprehensive dietary intake of a large group of nutraceuticals. It demonstrates the wide variety of polyphenols present in plant-derived foods as well as how many of these are regularly consumed. Further studies are needed to define the intake of phytonutrients in the diets of many different populations in a variety of geographic areas.

In addition to studies on macro- and micronutrients in cancer risk, the NCI has sponsored clinical studies testing efficacy of phytochemicals. Some concerns have been raised about the potential negative interactions of complementary and alternative modalities with traditional therapies, but a review of cancer studies found that antioxidants and other nutraceuticals usually do not interfere with, and in some cases can even enhance the effects or decrease the side effects of conventional cancer treatments (Simone et al. ).

The use of dietary-related CAM is common among cancer patients; CAM is generally used in support of traditional treatments to manage symptoms and improve quality of life, although often it is promoted as an alternative to mainstream therapies. Reports show that CAM usage is rising, both in cancer patients and the general public (van Tonder et al. ); much of this research portfolio has focused on cancer, and again, reflects growing interest in the action of nutraceuticals.