Fruits and vegetables do reduce the risk of cancer

Main Category: Nutrition / Diet
Also Included In: Preventive Medicine;  Cancer / Oncology
Article Date: 07 Nov 2004 - 11:00 PDT

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While this paper by Hung et al [2004] appears to be correct as reported, the conclusion that eating fruits and vegetables does not reduce the risk of cancer is very likely incorrect. Many studies have reported that frequent consumption of fruits and vegetables does, indeed, reduce the risk of cancer [Bosetti et al., 2000, 2001; McCann et al., 2003]. Thus, it is worthwhile to seek a reason for the difference in the findings by Hung et al and those by others.

One reason for the discrepancy appears to be that raw vegetables are associated with a greater risk reduction for cancer than are cooked vegetables [DuPont et al., 2000; Bossetti et al., 2001; Link and Potter, 2004]. Cooking, processing, and storing all reduce the amount of vitamins and minerals available, except for tomatoes, for which cooking increases the bioavialibility of lycopene, which has been found to reduce the risk of prostate cancer [Etminan et al., 2004].

Another possible omission was a consideration of allium family vegetables (garlic, onions, etc.). They have been shown to reduce the risk of breast, colon, prostate, and other cancers [Grant, 2004; Herman-Antosiewicz and Singh, 2004].

Finally, the way fruits and vegetables are grown and brought to market in the U.S. may make them less likely to have vitamins and minerals. Soils may be depleted of trace minerals such as selenium, which reduces the risk of cancer. Fruits may be picked before ripening, and may not develop the vitamins to their full potential in storage and forced ripening.

As always, more information can be found by searching PubMed
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi

So, lest those on diets that largely omit fruits and vegetables think that they are not increasing their risk of cancer, think again.

References
Bosetti C, La Vecchia C, Talamini R, Simonato L, Zambon P, Negri E, Trichopoulos D, Lagiou P, Bardini R, Franceschi S. Food groups and risk of squamous cell esophageal cancer in northern Italy. Int J Cancer. 2000 Jul 15;87(2):289-94.

Bosetti C, Negri E, Franceschi S, Pelucchi C, Talamini R, Montella M, Conti E, La Vecchia C. Diet and ovarian cancer risk: a case-control study in Italy. Int J Cancer. 2001 Sep15;93(6):911-5.

DuPont MS, Mondin Z, Williamson G, Price KR. Effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive. J Agric Food Chem. 2000 Sep;48(9):3957-64.

Etminan M, Takkouche B, Caamano-Isorna F. The role of tomato products and lycopene in the prevention of prostate cancer: a meta-analysis of observational studies. Cancer Epidemiol Biomarkers Prev. 2004 Mar;13(3):340-5.

Grant WB. Allium family vegetables (garlic, leeks, onions, scallions) reduce the risk of cancer (and cardiovascular disease). 2004. http://www.sunarc.org/papers.htm

Herman-Antosiewicz A, Singh SV. Signal transduction pathways leading to cell cycle arrest and apoptosis induction in cancer cells by Allium vegetable-derived organosulfur compounds: a review. Mutat Res. 2004 Nov 2;555(1-2):121-31.

Hung HC, Joshipura KJ, Jiang R, Hu FB, Hunter D, Smith-Warner SA, Colditz GA, Rosner B, Spiegelman D, Willett WC. Fruit and vegetable intake and risk of major chronic disease.J Natl Cancer Inst. 2004 Nov 3;96(21):1577-84.

Link LB, Potter JD. Raw versus cooked vegetables and cancer risk. Cancer Epidemiol Biomarkers Prev. 2004 Sep;13(9):1422-35.

McCann SE, Freudenheim JL, Marshall JR, Graham S. Risk of human ovarian cancer is related to dietary intake of selected nutrients, phytochemicals and food groups. J Nutr. 2003 Jun;133(6):1937-42.

posted by William B. Grant Ph.D. on 05 November 2004 at 10:32 pm