In this review of the scientific literature on the relationship between vegetable and fruit consumption and risk of cancer, results from 206 human epidemiologic studies and 22 animal studies are summarized. The evidence for a protective effect of greater vegetable and fruit consumption is consistent for cancers of the stomach, esophagus, lung, oral cavity and pharynx, endometrium, pancreas, and colon. The types of vegetables or fruit that most often appear to be protective against cancer are raw vegetables, followed by allium vegetables, carrots, green vegetables, cruciferous vegetables, and tomatoes. Substances present in vegetables and fruit that may help protect against cancer, and their mechanisms, are also briefly reviewed; these include dithiolthiones, isothiocyanates, indole-3-carbinol, allium compounds, isoflavones, protease inhibitors, saponins, phytosterols, inositol hexaphosphate, vitamin C, D-limonene, lutein, folic acid, beta carotene, lycopene, selenium, vitamin E, flavonoids, and dietary fiber. Current US vegetable and fruit intake, which averages about 3.4 servings per day, is discussed, as are possible noncancer-related effects of increased vegetable and fruit consumption, including benefits against cardiovascular disease, diabetes, stroke, obesity, diverticulosis, and cataracts. Suggestions for dietitians to use in counseling persons toward increasing vegetable and fruit intake are presented. J Am Diet Assoc. 1996; 96:1027-1039.

Vegetables, Fruit, and Cancer Prevention: A Review

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.

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Tomatoes, Tomato-Based Products, Lycopene, and Cancer: Review of the Epidemiologic Literature

https://faculty.missouri.edu/~glaserr/3700s14/Antioxidant_Carotenoids_2005.pdf

Carotenoid actions and their relation to health and disease.

Epidemiologic evidence of the protective effect of fruit and vegetables on cancer risk

Dietary carotenoids are thought to provide health benefits in decreasing the risk of disease, particularly certain cancers and eye disease. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein, and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Furthermore, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

The Role of Carotenoids in Human Health

A multi-centre case-control study on bladder cancer and diet was carried out in 5 regions of Spain. We report results on 432 male cases and 792 matched controls. Usual dietary habits were investigated by means of an interview-based dietary history questionnaire. Bladder-cancer cases were selected from the registers of 12 hospitals located in the study areas. Each case was matched by sex, age and area of residence to 2 controls, one identified in the same hospital and one drawn from population lists. Descriptive analyses indicated that the average dietary pattern was typical of Mediterranean populations: a high P/S ratio, high intake of fish, fruits and vegetables and moderate or low intake of meat and dairy products. Relative risks for specific foods and nutrients were adjusted for tobacco smoking and energy intake. Subjects in the highest quarter of intake of saturated fat had a significantly increased risk of bladder cancer (RR for highest quarter = 2.25; 95% CI = 1.42 to 3.55). Moderate increases in risk for high intake of mono-unsaturated fats and calcium, and a slight decrease for iron were also found, but these disappeared after adjustment for saturated fat. Intake of vitamin E was related to slightly reduced risk (RR for highest quarter = 0.72; 95% CI = 0.48 to 1.09) which was not modified by adjustment for fat. No association was found with intake of retinol or carotene. These results, along with those of previous studies, suggest that saturated fat intake may influence the occurrence of bladder cancer.

Diet and bladder cancer in Spain : a multi-centre case-control study

A case-control study on bladder cancer was carried out in four regions of Spain. The study included 497 cases (438 males and 59 females), 583 hospital controls and 530 population controls matched by sex, age and residence. The present paper reports the results of the analyses on occupational history. Among men, an increased risk of bladder cancer was found for textile workers (OR = 1.97, 95% CL 1.2-3.3), mechanics and maintenance workers (OR = 1.86, 95% CL 1.2-2.8), workers in the printing industry (OR = 2.06, 95% CL 1.0-4.3) and for managers (OR = 2.03, 95% CL 1.2-3.5). The risk was highest among those first employed in the textile industry before the age of 25 and prior to 1960. Among mechanics the risk was highest for those who started after the age of 25 and later than 1960. The OR for smokers who had also been employed in one of the high risk occupations was 7.82 (95% CL 4.4-14.0) which is compatible with a multiplicative effect of joint exposure to tobacco and occupational hazards.

Occupation and Bladder Cancer in Spain: A Multi-Centre Case-Control Study

The association between tobacco smoking and bladder cancer was investigated in a multicenter case-control study conducted in five provinces of Spain between 1983 and 1986. A matched analysis was carried out in males, based on 430 histologically confirmed cases, 405 hospital controls, and 386 population controls, matched by age and place of residence. An increased risk was found for smokers as compared with nonsmokers (odds ratio (OR) = 3.79, 95% confidence intervals (CI) 2.41-5.97), and this increase was significantly associated with the intensity of smoking. Smokers of filter-tipped cigarettes had a reduced risk as compared with smokers of non-filter-tipped cigarettes (OR = 0.57, 95% CI 0.32-1.02). A diminution of risk was also observed for smokers of low-tar and low-nicotine ("light") cigarettes. Depth of inhalation was strongly associated with illness. No difference was shown in the logistic regression model between smokers of black tobacco and smokers of blond tobacco after controlling for depth of inhalation. Although the number of persons who smoked blond tobacco exclusively was small, the results suggest that it is important to consider inhalation patterns when studying risk variations between smokers of black tobacco and smokers of blond tobacco. The age at which a person started to smoke did not appear to affect risk. An analysis of the decrease in risk associated with years since quitting smoking suggested that different components of cigarette smoke may play a role at different stages of the carcinogenic process.

Tobacco Smoke Inhalation Pattern, Tobacco Type, and Bladder Cancer in Spain

Urinary infection, renal lithiasis and bladder cancer in Spain.

The association between coffee consumption and bladder cancer was investigated in a multi-centre case-control study conducted in Spain from 1983 to 1986. A total of 497 cases (438 male and 59 female) with histopathologically confirmed bladder cancer were used in the analysis along with 566 hospital controls and 547 population controls. Odds ratios (OR), adjusted for age, province of residence, occupations at risk, consumption of artificial sweeteners and cigarette smoking, did not show any association between coffee consumption and bladder cancer for either sex. However, in non-smokers and mainly in males, for current coffee drinkers the OR was 2.78 (95% [Cl]: 0.78-9.87), while for drinkers of 2-7, 8-14 and > or = 15 cups/week the respective OR were 2.22, 3.11 and 1.87 with a dose-response relationship for lifelong consumption and years of exposure to regular coffee consumption. The OR in male non-smokers and current coffee drinkers were 2.36 (95% Cl: 0.62-9.05) with population controls only and 1.94, 2.58 and 1.48 for the corresponding levels of intensity of consumption (cups/week). The associations observed in non-smokers suggest the existence of a possible association between coffee consumption and bladder cancer, but are based on small numbers and need to be confirmed in larger studies.

Manuel Errezola

Papers

Diet and bladder cancer in Spain : a multi-centre case-control study

Occupation and Bladder Cancer in Spain: A Multi-Centre Case-Control Study

Tobacco Smoke Inhalation Pattern, Tobacco Type, and Bladder Cancer in Spain

Urinary infection, renal lithiasis and bladder cancer in Spain.

Bladder cancer and coffee consumption in smokers and non-smokers in Spain.