Cancer-protective effect

The present results also point to differences between the mammary tumor model and the ACT model for evaluating the potential cancer protective effects of Se in broccoli. A previous study (17) showed that high-Se broccoli florets decreased the number of DMH-induced ACT. Similarly, in the present study high-Se broccoli sprouts decreased DMH-induced ACT, but low-Se broccoli sprouts alone did not have any effect (Table 3). In the mammary tumor model, however, broccoli alone, similar to garlic alone (3), reduced the number of tumors (Table 1). This contrasting effect could be the result of a difference between tumor and preneoplastic lesion models, a difference between carcinogens, or a difference between mammary and colonic tissues. 

The dose relationsl ps betweoi food constituents and dieir efficacies for prevention of "life style>rdated diseases" induding cemco have been proven in The dose relaticmsh s between food constituents and dieir efficacies ftn prevention of "life style dated diseases" induding cracer have been proven in recent decades. While attention has been frequently paid to anti-oxidative vitamins or pdyphcnols for the preventicm of carcinogenesis in rodents, the above-mentioned ubiquitous phytochemicals do not exclusively rqtresent the benefidal, cancer-protective effect of vegetable intake vdien the great diversity ai plant secondary metabolites is taken into account. 

Currently research on the cancer-protecting effects of selenium is being conducted in laboratories all over the world. 

Urethane [51-79-6] (ethyl carbamate) occurs as a natural by-product in fermented products such as wine, Hquors, yogurt, beer, bread, oHves, cheeses, and soy sauces. Whereas urethane has a known cancer etiology in experimental animals, no such relationship has yet been proven in humans (108,109). Alcohol may act by blocking the metaboHsm of urethane, and thus exert a protective effect in humans consuming alcohoHc beverages (110). 

Several studies have investigated the role of dietary factors in prostate cancer risk, but results appear inconsistent. Significant effects have not been detected for dietary soya products certain vegetables, beans, fruit, rice and seaweed appear to be protective in some studies, while another has shown no protective effect from seaweed or vegetable consumption. In addition, a number of other risk factors have been shown to be associated with an increased risk of this cancer, including meat and dairy products and carotenoids. 

Thus, it is uncertain to what extent the apparent protective effects of fruit and vegetable consumption on risk of stomach cancer can be attributable to their phytoestrogen content. This appears not to have been studied directly, and other constituents such as ascorbic acid (vitamin C), a-tocopherol (vitamin E) and /1-carotene may be potentially protective. 

NB There is also conclusive evidence that these agents have a protective effect against cancers of the ovary and endometrium) Oral contraceptives, sequential (Suppl. 7 1987)... 

Studies with fenretinide in woman with stage I breast cancer did not show an overall effect of decreasing the risk of contralateral breast cancer. A protective effect could only be observed in premenopausal women, probably due to the modulation of the insulin-like growth factor 1 (IGF-1) by fenretinide in this population. 

Vitamin C occurs as L-ascorbic acid and dihydroascorbic acid in fruits, vegetables and potatoes, as well as in processed foods to which it has been added as an antioxidant. The only wholly undisputed function of vitamin C is the prevention of scurvy. Although this is the physiological rationale for the currently recommended intake levels, there is growing evidence that vitamin C may provide additional protective effects against other diseases including cancer, and the recommended dietary allowance (RDA) may be increased in the near future. Scurvy develops in adults whose habitual intake of vitamin C falls below 1 mg/d, and under experimental conditions 10 mg/d is sufficient to prevent or alleviate symptoms (Bartley et al., 1953). The RDA is 60 mg per day in the USA, but plasma levels of ascorbate do not achieve saturation until daily intakes reach around 100 mg (Bates et al., 1979). Most of the ascorbate in human diets is derived from natural sources, and consumers who eat five portions, or about 400-500 g, of fruits and vegetables per day could obtain as much as 200 mg of ascorbate. 

GERBER M, BOUTRON-RUAULT M c and HEREBERG s et al. (2002) Food and cancer state of the art about the protective effect of fruits and vegetables , Bull Cancer, 89, 293-312. Resum.htm. 

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