Understanding how environment, crop management, and other factors, particularly soil fertility, influence the composition and quality of food crops is necessary for the production of high-quality nutritious foods. The flavonoid aglycones quercetin and kaempferol were measured in dried tomato samples (Lycopersicon esculentum L. cv. Halley 3155) that had been archived over the period from 1994 to 2004 from the Long-Term Research on Agricultural Systems project (LTRAS) at the University of California-Davis, which began in 1993. Conventional and organic processing tomato production systems are part of the set of systems compared at LTRAS. Comparisons of analyses of archived samples from conventional and organic production systems demonstrated statistically higher levels (P < 0.05) of quercetin and kaempferol aglycones in organic tomatoes. Ten-year mean levels of quercetin and kaempferol in organic tomatoes [115.5 and 63.3 mg g-1 of dry matter (DM)] were 79 and 97% higher than those in conventional tomatoes (64.6 and 32.06 mg g-1 of DM), respectively. The levels of flavonoids increased over time in samples from organic treatments, whereas the levels of flavonoids did not vary significantly in conventional treatments. This increase corresponds not only with increasing amounts of soil organic matter accumulating in organic plots but also with reduced manure application rates once soils in the organic systems had reached equilibrium levels of organic matter. Well-quantified changes in tomato nutrients over years in organic farming systems have not been reported previously.

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Alyson E. Mitchell,* Yun-Jeong Hong, Eunmi Koh, Diane M. Barrett, D. E. Bryant, R. Ford Denison,# and Stephen Kaffka

J. Agric. Food Chem., 55 (15), 6154 -6159, 2007. 10.1021/jf070344+ S0021-8561(07)00344-5

Department of Food Science and Technology and Department of Plant Sciences, One Shields Avenue, University of California-Davis, Davis, California 95616, and Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota 55108

Prostate cancer has become a major public health problem worldwide. Yet, the etiology of prostate cancer remains largely unknown. Dietary factors, dietary supplements, and physical activity might be important in the prevention of the disease. In the majority of studies, it was observed that high consumption of meat and dairy products has been linked to a greater risk. In contrast, frequent consumption of fatty fish and tomato products has been associated with a reduced risk. It has been shown consistently that high levels of circulating insulin-like growth factor 1 (IGF-1) are associated with an increased risk of prostate cancer. Dietary factors are also recognized as determinants of circulating IGF-1, thus changes in diet may influence IGF-1 concentrations in serum. Furthermore, increased intake of vitamin E and selenium (from supplements) has been shown in intervention studies to decrease the risk. Possibly, high level of physical activity is also associated with decreased risk of prostate cancer. The accumulated scientific evidence concerning the associations between diet, lifestyle, and risk of prostate cancer development suggests that there are some identified modifiable risk factors that it might be recommended to change in order to decrease the risk for this common cancer site.

Wolk A.

Division of Nutritional Epidemiology, the National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. Alicja.Wolk@imm.ki.se

Acta Oncol. 2005;44(3):277-81.Links

The epidemiologic literature in the English language regarding intake of tomatoes and tomato-based products and blood lycopene (a compound derived predominantly from tomatoes) level in relation to the risk of various cancers was reviewed. Among 72 studies identified, 57 reported inverse associations between tomato intake or blood lycopene level and the risk of cancer at a defined anatomic site; 35 of these inverse associations were statistically significant. No study indicated that higher tomato consumption or blood lycopene level statistically significantly increased the risk of cancer at any of the investigated sites. About half of the relative risks for comparisons of high with low intakes or levels for tomatoes or lycopene were approximately 0.6 or lower. The evidence for a benefit was strongest for cancers of the prostate, lung, and stomach. Data were also suggestive of a benefit for cancers of the pancreas, colon and rectum, esophagus, oral cavity, breast, and cervix. Because the data are from observational studies, a cause-effect relationship cannot be established definitively. However, the consistency of the results across numerous studies in diverse populations, for case-control and prospective studies, and for dietary-based and blood-based investigations argues against bias or confounding as the explanation for these findings. Lycopene may account for or contribute to these benefits, but this possibility is not yet proven and requires further study. Numerous other potentially beneficial compounds are present in tomatoes, and, conceivably, complex interactions among multiple components may contribute to the anticancer properties of tomatoes. The consistently lower risk of cancer for a variety of anatomic sites that is associated with higher consumption of tomatoes and tomato-based products adds further support for current dietary recommendations to increase fruit and vegetable consumption.

Giovannucci E.

Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA. edward.giovannucci@channing.harvard.edu

J Natl Cancer Inst. 1999 Feb 17;91(4):317-31.