It is estimated that nearly one-third of all cancer deaths in the United States could be prevented through appropriate dietary modification. Various dietary antioxidants have shown considerable promise as effective agents for cancer prevention by reducing oxidative stress which has been implicated in the development of many diseases, including cancer. Therefore, for reducing the incidence of cancer, modifications in dietary habits, especially by increasing consumption of fruits and vegetables rich in antioxidants, are increasingly advocated. Accumulating research evidence suggests that many dietary factors may be used alone or in combination with traditional chemotherapeutic agents to prevent the occurrence of cancer, their metastatic spread, or even to treat cancer. The reduced cancer risk and lack of toxicity associated with high intake of fruits and vegetables suggest that specific concentrations of antioxidant agents from these dietary sources may produce cancer chemopreventive effects without causing...

Cancer chemoprevention through dietary antioxidants: progress and promise.

Overwhelming evidence suggests that edible small and soft-fleshed berry fruits may have beneficial effects against several types of human cancers. The anticancer potential of berries has been related, at least in part, to a multitude of bioactive phytochemicals that these colorful fruits contain, including polyphenols (flavonoids, proanthocyanidins, ellagitannins, gallotannins, phenolic acids), stilbenoids, lignans, and triterpenoids. Studies show that the anticancer effects of berry bioactives are partially mediated through their abilities to counteract, reduce, and also repair damage resulting from oxidative stress and inflammation. In addition, berry bioactives also regulate carcinogen and xenobiotic metabolizing enzymes, various transcription and growth factors, inflammatory cytokines, and subcellular signaling pathways of cancer cell proliferation, apoptosis, and tumor angiogenesis. Berry phytochemicals may also potentially sensitize tumor cells to chemotherapeutic agents by inhibiting pathways that lead to treatment resistance, and berry fruit consumption may provide protection from therapy-associated toxicities. Although a wide variety of berry fruits are consumed worldwide, this paper focuses on those commonly consumed in North America, namely, blackberries, black raspberries, blueberries, cranberries, red raspberries, and strawberries. In addition, a large body of studies on singly purified berry bioactives is available, but this paper focuses on studies of "whole berries" per se, that is, as berry extracts and purified fractions, juices, and freeze-dried powders. Potential mechanisms of anticancer action and bioavailability of berry phenolics, as well as gaps in knowledge and recommendations for future berry research, are also briefly discussed.

Berry fruits for cancer prevention: current status and future prospects.

Emerging evidence is elucidating how non-nutrient phytochemicals underlie the health promotion afforded by fruits and vegetables. This review focuses on Vaccinium macrocarpon, the American cranberry, compiling a comprehensive list of its known phytochemical components, and detailing their prevalence in cranberry fruit and its products. Flavonoids, especially colored anthocyanins, abundant flavonols, and unique proanthocyanidins, have attracted major research attention. Other notable active components include phenolic acids, benzoates, hydroxycinnamic acids, terpenes and organic acids. Health effects of cranberries, cranberry products, and isolated cranberry components in humans and animals, as well as in vitro, are debated. Evidence for protection from several bacterial pathogens, cancer, cardiovascular disease, and inflammation is compelling, while neuroprotection and anti-viral activity also have begun to draw new consideration. Emerging bioavailability data is considered and potential molecular mechanisms are evaluated, linking phytochemicals to health effects through their biochemical properties and reactions. Finally, the effects of processing and storage on cranberry phytochemicals is discussed, with a focus on identifying research gaps and novel means to preserve their natural, health-promoting components.

Phytochemicals of cranberries and cranberry products: characterization, potential health effects, and processing stability.

Pomegranate, a fruit native to the Middle East, has gained widespread popularity as a functional food and nutraceutical source. The health effects of the whole fruit, as well as its juices and extracts, have been studied in relation to a variety of chronic diseases. Promising results against cardiovascular disease, diabetes, and prostate cancer have been reported from human clinical trials. The in vitro antioxidant activity of pomegranate has been attributed to its high polyphenolic content, specifically punicalagins, punicalins, gallagic acid, and ellagic acid. These compounds are metabolized during digestion to ellagic acid and urolithins, suggesting that the bioactive compounds that provide in vivo antioxidant activity may not be the same as those present in the whole food. Anthocyanins and the unique fatty acid profile of the seed oil may also play a role in pomegranate's health effects. A more complete characterization of pomegranate components and their physiological fate may provide mechanistic insight into the potential health benefits observed in clinical trials.

Pomegranate as a Functional Food and Nutraceutical Source

Increasing incidences of some chronic diseases, including cancer and cardiovascular disease, especially in industrial countries, have raised awareness regarding the importance of diet (Erbersdobler 2003). It is estimated that one-third of the cancer cases and up to half of cardiovascular disease cases are thought to be diet related (Goldberg 1994). Numerous epidemiological studies have shown an inverse association between fruit and vegetable consumption and chronic diseases, including different types of cancer and cardiovascular disease (Hirayama 1990; Block and others 1992; Howe and others 1992; Steinmetz and Potter 1991, 1996; World Cancer Research Fund 1997; Joshipura and others 2001; Bazzano and others 2002; Kris-Etherton and others 2002). These studies have shown mounting evidence that people who avoid fruit and vegetables completely, or who consume very little, are indeed at increased risk of these diseases. Therefore, interest in the health benefits of fruit and vegetable consumption is increasing, and the interest in understanding the type, number, and mode of action of the different components in fruits and vegetables that confer health benefits is also increasing. Fruits and vegetables have historically been considered rich sources of some essential dietary micronutrients and fibers, and more recently they have been recognized as important sources for a wide array of phytochemicals that individually, or in combination, may benefit health (Stavric 1994; Rechkemmer 2001). Therefore, some people have conferred on fruits and vegetables the status of “functional foods.” There are many biologically plausible reasons for this potentially protective association, including the fact that many of the phytochemicals act as antioxidants. Phytochemicals present in fruits and vegetables are very diverse, such as ascorbic acid, carotenoids, and phenolic compounds (Liu 2004; Percival and others 2006; Syngletary and others 2005; Yahia and others 2001a, 2001b). Plant polyphenols are ubiquitous in the diet, with rich sources being tea, wine, fruits, and vegetables; they demonstrate considerable antioxidative activity in vitro, which can have important implications for health (Duthie and others 2000). Naturally occurring compounds such as phytochemicals, which possess anticarcinogenic and other beneficial properties, are referred to as chemopreventers. One of the predominant mechanisms of their protective action is due to their antioxidant activity and the capacity to scavenge free radicals. Among the most investigated chemopreventers are some vitamins, plant polyphenols, and pigments such as carotenoids, chlorophylls, flavonoids, and betalains. Resolution of the potential protective roles of

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The Contribution of Fruit and Vegetable Consumption to Human Health

Selected fruits reduce azoxymethane (AOM)-induced aberrant crypt foci (ACF) in Fisher 344 male rats

This study was designed to evaluate the anticarcinogenic effect of Flax Seed Meal (FSM) (10 and 20%) and Flax Seed Oil (FSO) (7 and 14%) on Azoxymethane (AOM)-induced colon tumors in Fisher 344 male rats during initiation (I), promotion (P) and Initiation + Promotion (I+P) stages of carcinogenesis. After an acclimatization period of 1 week, 14 groups of Fisher 344 male weanling rats, 3-4 week old (15 per group) were assigned to 2 control groups fed AIN 93G diet and AIN 93G + 14% soybean oil (SBO) (high fat control). The remaining 12 groups were assigned to 10 and 20% FSM (I, P and I+P) and 7 and 14% FSO (I, P and I+P). All rats received 16 mg kg-1 body weight of AOM at 7 and 8 week of age. At 20 weeks of age all animals were switched to AIN-93 M diets and at 45 week of age all rats were killed by CO2 asphyxiation. Tumor incidence (%) in colon of rats fed C (7 and 14%) was both 100. Tumor incidences for rats fed FSO (7 and 14%) at I, P and I+P were: 100, 100, 61, 60, 58 and 61, respectively and 80, 80, 66.6, 66.6, 66.6 and 31, respectively for rats fed FSM (10 and 20%) at I, P and I+P. Tumors per tumor-bearing ratios for groups fed C; 10 and 20% FSM (I, P and I + P) were 3.86, 1.28, 1.70, 1.75 and 1.0, 0.94, 0.64, respectively. In rats fed C (7 and 14%) and 7 and 14% FSO (I, P and I + P) T/TBR ratios were 3.86, 5.96; 1.4, 0.6, 0.6; 1.90, 0.8, 0.8, respectively. Glutathione-S-Transferase activity (a phase II detoxification enzyme) was significantly (p<0.05) higher in rats fed 10 and 20% FSM and 7 and 14% FSO compared to controls. The results of this study indicate that bioactive phytochemicals such as dietary fiber and lignans such as secoisolariciresinol diglycoside (SDG) found in flax seed meal and essential fatty acids such as α-linolenic acid (ALA) found in flax seed oil suppress colon tumors, particularly at the promotion stage and flax seed products may therefore be effective chemopreventive agents.

https://pubag.nal.usda.gov/download/35390/PDF

M. Guyton

Papers

Selected fruits reduce azoxymethane (AOM)-induced aberrant crypt foci (ACF) in Fisher 344 male rats

Chemopreventive Effects of Flax Seed Oil and Flax Seed Meal on Azoxymethane-Induced Colon Tumors in Fisher 344 Male Rats

Determination of Antioxidant Contents in Red Sorrel and its nticarcinogenic Potential in Azoxymethane-Induced Colonic Aberrant Crypt Foci

Inhibitory Effects of Feeding Selected Levels of Peanuts on Azoxymethane-Induced Aberrant Crypt Foci in Male Fisher 344 Rats