Intake of fruits and vegetables and polymorphisms in DNA repair genes in bladder cancer

Unveiling the Effects of Cruciferous Vegetable Intake on Different Cancers: A Systematic Review and Dose-Response Meta-analysis

CONTEXT

Epidemiological studies indicated that cruciferous vegetable intake is associated with positive health outcomes. However, the role of cruciferous vegetables may have differential impacts on various cancers.

OBJECTIVE

This meta-analysis aims to review recent epidemiological studies on the link between cruciferous vegetables and various cancers. It seeks to identify the optimal intake dose and timing of cruciferous vegetables influencing their association with cancer risk.

DATA SOURCES

Studies on cruciferous vegetables and cancer were searched in PubMed, NCBI, Web of Science, and Elsevier databases from 1978 to June 2023.

DATA EXTRACTION

Extracted data from 226 relevant case-control and cohort studies were expressed by standardized mean difference and 95% CI, followed by the subgroup analysis to eliminate heterogeneity.

RESULTS

Intake of cruciferous vegetables can prevent cancers, with an odds ratio of 0.77 and risk ratio (RR) of 0.96. The intake levels of cruciferous vegetables associated with the risk of colorectal cancer, lung cancer, upper gastrointestinal cancer, gynecological cancer (ovarian cancer and endometrial cancer), bladder cancer, renal cancer, and prostate cancer were found to be 5.41 servings/week, 5.41 servings/week, 5.5 servings/week, 7.4 servings/week, 5.5 servings/week, 4.85 servings/week, and 3 servings/week, respectively. In a cohort followed for 2 to 15 years, limited consumption of cruciferous vegetables was correlated with a higher cancer RR. In the Asian population, cruciferous vegetables had a significant relationship with lung cancer, head and neck squamous cell carcinoma, and esophageal cancer. Conversely, cruciferous vegetables are predominantly associated with colorectal, renal, gynecological, and prostate cancer in the American population.

CONCLUSION

This study highlights the complex link between cruciferous vegetables and cancer, influenced by factors such as cancer type, region, intake level, and follow-up duration.

Fruits and vegetables intake and bladder cancer risk: a pooled analysis from 11 case-control studies in the BLadder cancer Epidemiology and Nutritional Determinants (BLEND) consortium

PURPOSE

High consumption of fruits and vegetables decrease the risk of bladder cancer (BC). The evidence of specific fruits and vegetables and the BC risk is still limited.

METHODS

Fruit and vegetable consumptions in relation to BC risk was examined by pooling individual participant data from case-control studies. Unconditional logistic regression was used to estimate study-specific odds ratio's (ORs) with 95% confidence intervals (CIs) and combined using a random-effects model for intakes of total fruits, total vegetables, and subgroups of fruits and vegetables.

RESULTS

A total of 11 case-control studies were included, comprising 5637 BC cases and 10,504 controls. Overall, participants with the highest intakes versus the lowest intakes of fruits in total (OR 0.79; 95% CI 0.68-0.91), citrus fruits (OR 0.81; 95% CI 0.65-0.98), pome fruits (OR 0.76; 95% CI 0.65-0.87), and tropical fruits (OR 0.84; 95% CI 0.73-0.94) reduced the BC risk. Greater consumption of vegetables in total, and specifically shoot vegetables, was associated with decreased BC risk (OR 0.82; 95% CI 0.68-0.96 and OR 0.87; 95% CI 0.78-0.96, respectively). Substantial heterogeneity was observed for the associations between citrus fruits and total vegetables and BC risk.

CONCLUSION

This comprehensive study provides compelling evidence that the consumption of fruits overall, citrus fruits, pome fruits and tropical fruits reduce the BC risk. Besides, evidence was found for an inverse association between total vegetables and shoot vegetables intake.

Food groups and urologic cancers risk: a systematic review and meta-analysis of prospective studies

BACKGROUND

To assess the association between 12 food groups intake and the risk of urologic cancers.

METHODS

We scanned PubMed and Web of Science databases up to April 1st, 2023, and 73 publications met the inclusion criteria in the meta-analysis. We used a random effects model to estimate the summary risk ratios (RRs) and 95% confidence intervals (95% CI).

RESULTS

In the linear dose-response meta-analysis, an inverse association was found between each additional daily 100 g of fruits [RR: 0.89, 95%CI = (0.83, 0.97)], 100 g of vegetables [RR: 0.92, 95%CI = (0.85, 0.99)], 12 g of alcohol [RR: 0.91, 95%CI = (0.88, 0.94)] and 1 cup of coffee [RR: 0.95, 95%CI = (0.83, 0.97)] intake and the risk of renal cell carcinoma. Conversely, each additional daily 100 g of red meat intake was positively associated with renal cell carcinoma [RR: 1.41, 95%CI = (1.03, 2.10)]. Inverse associations were observed between each additional daily 50 g of egg [RR: 0.73, 95%CI = (0.62, 0.87)] and each additional daily 1 cup of tea consumption and bladder cancer risk [RR: 0.97, 95%CI = (0.94, 0.99)]. There were no significant associations for nonlinear dose-response relationships between 12 food groups and urological cancers.

CONCLUSION

Our meta-analysis strengthens the evidence that appropriate intake of specific food groups, such as fruits, vegetables, alcohol, tea, and coffee, is associated with the risk of renal cell carcinoma or bladder cancer. More studies are required to fill the knowledge gap on the links between various food groups and urologic cancers because the evidence was less credible in this meta-analysis.

SYSTEMATIC REVIEW REGISTRATION

This study was registered on PROSPERO (CRD42022340336).

The effects of the interaction of genetic predisposition with lifestyle factors on bladder cancer risk

OBJECTIVES

To investigate the association of polygenic risk score (PRS) and bladder cancer (BC) risk and whether this PRS can be offset by a healthy lifestyle.

METHODS

Individuals with BC (n = 563) and non-BC controls (n = 483 957) were identified in the UK Biobank, and adjusted Cox regression models were used. A PRS was constructed based on 34 genetic variants associated with BC development, while a healthy lifestyle score (HLS) was constructed based on three lifestyle factors (i.e., smoking, physical activity, and diet).

RESULTS

Overall, a negative interaction was observed between the PRS and the HLS (P = 0.02). A 7% higher and 28% lower BC risk per 1-standard deviation (SD) increment in PRS and HLS were observed, respectively. A simultaneous increment of 1 SD in both HLS and PRS was associated with a 6% lower BC risk. In addition, individuals with a high genetic risk and an unfavourable lifestyle showed an increased BC risk compared to individuals with low genetic risk and a favourable lifestyle (hazard ratio 1.55, 95% confidence interval 1.16-1.91; P for trend <0.001). Furthermore, population-attributable fraction (PAF) analysis showed that 12%-15% of the BC cases might have been prevented if individuals had adhered to a healthy lifestyle.

CONCLUSION

This large-scale cohort study shows that a genetic predisposition combined with unhealthy behaviours have a joint negative effect on the risk of developing BC. Behavioural lifestyle changes should be encouraged for people through comprehensive, multifactorial approaches, although high-risk individuals may be selected based on genetic risk.

Clinical Potential of Fruit in Bladder Cancer Prevention and Treatment

Bladder cancer (BC) is the most common tumor of the urinary system in the world. Moreover, despite using anticancer therapies, BC is also characterized by a high recurrence risk. Among numerous risk factors, cigarette smoking, occupational exposure to certain aromatic compounds, and genetic factors contribute most strongly to BC development. However, the epidemiological data to date suggests that diet quality may influence some carcinogenic factors of BC and, therefore, might have a preventative effect. Adequate consumption of selected fruits with scientifically proven properties, including pomegranates and cranberries, can significantly reduce the risk of developing BC, even in those at risk. Therefore, in this article, we aim to elucidate, using available literature, the role of fruits, including pomegranates, cranberries, citrus fruits, cactus pears, and apples, in BC prevention and treatment. Previous data indicate the role of compounds in the above-mentioned fruits in the modulation of the signaling pathways, including cell proliferation, cell growth, cell survival, and cell death.

The Green Anti-Cancer Weapon. The Role of Natural Compounds in Bladder Cancer Treatment

Bladder cancer (BC) is the second most common genitourinary cancer. In 2018, 550,000 people in the world were diagnosed with BC, and the number of new cases continues to rise. BC is also characterized by high recurrence risk, despite therapies. Although in the last few years, the range of BC therapy has considerably widened, it is associated with severe side effects and the development of drug resistance, which is hampering treatment success. Thus, patients are increasingly choosing products of natural origin as an alternative or complementary therapeutic options. Therefore, in this article, we aim to elucidate, using the available literature, the role of natural substances such as curcumin, sulforaphane, resveratrol, quercetin, 6-gingerol, delphinidin, epigallocatechin-3-gallate and gossypol in the BC treatment. Numerous clinical and preclinical studies point to their role in the modulation of the signaling pathways, such as cell proliferation, cell survival, apoptosis and cell death.

Apple intake and cancer risk: a systematic review and meta-analysis of observational studies

OBJECTIVE

Conflicting results on the association between fruit consumption and cancer risk have been reported. Little is known about the cancer preventive effects of different fruit types. The present meta-analysis investigates whether an association exists between apple intake and cancer risk.

DESIGN

Relevant observational studies were identified by literature search (PubMed, Web of Science and Embase). A random-effect model was used to estimate the cancer risk in different anatomical sites. Between-study heterogeneity and publication bias were assessed using adequate statistical tests.

RESULTS

Twenty case-control (three on lung, five on colorectal, five on breast, two on oesophageal, three on oral cavity, two on prostate and one each on pancreas, bladder, larynx, ovary, kidney and brain cancer) and twenty-one cohort (seven on lung, two on colorectal, three on breast and one each on oesophageal, pancreas, bladder, kidney, endometrial, head-neck, urothelial and stomach cancer) studies met the inclusion criteria. Comparing the highest v. lowest level of apple consumption, the reduction of lung cancer risk was statistically highly significant in both case-control (OR=0·75; 95% CI 0·63, 0·88; P=0·001, I 2=0 %) and cohort studies (relative risk=0·89; 95% CI 0·84, 0·94; P<0·001, I 2=53 %). Instead, in the case of colorectal (OR=0·66; 95% CI 0·54, 0·81; P<0·001, I 2=55%), breast (OR=0·79; 95% CI 0·73, 0·87; P<0·001, I 2=1 %) and overall digestive tract (OR=0·50; 95% CI 0·36, 0·69; P<0·001, I 2=90 %) cancers a significant preventive effect of apples was found only in case-control studies while prospective studies indicated no effect. No evidence of publication bias could be detected for colorectal, oral cavity, oesophageal and breast cancer. However, some confounding effects may be present and related to the consumption of other fruit which have not been considered as adjusting factors.

CONCLUSIONS

The present meta-analysis indicates that consumption of apples is associated with a reduced risk of cancer in different anatomical sites.

Flavonoid and lignan intake in relation to bladder cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

BACKGROUND

There is growing evidence of the protective role of dietary intake of flavonoids and lignans on cancer, but the association with bladder cancer has not been thoroughly investigated in epidemiological studies. We evaluated the association between dietary intakes of total and subclasses of flavonoids and lignans and risk of bladder cancer and its main morphological type, urothelial cell carcinoma (UCC), within the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

METHODS

A cohort of 477 312 men and women mostly aged 35-70 years, were recruited in 10 European countries. At baseline, dietary flavonoid and lignan intakes were estimated using centre-specific validated questionnaires and a food composition database based on the Phenol-Explorer, the UK Food Standards Agency and the US Department of Agriculture databases.

RESULTS

During an average of 11 years of follow-up, 1575 new cases of primary bladder cancer were identified, of which 1425 were UCC (classified into aggressive (n=430) and non-aggressive (n=413) UCC). No association was found between total flavonoid intake and bladder cancer risk. Among flavonoid subclasses, significant inverse associations with bladder cancer risk were found for intakes of flavonol (hazard ratio comparing fifth with first quintile (HRQ5-Q1) 0.74, 95% confidence interval (CI): 0.61-0.91; P-trend=0.009) and lignans (HRQ5-Q1 0.78, 95% CI: 0.62-0.96; P-trend=0.046). Similar results were observed for overall UCC and aggressive UCC, but not for non-aggressive UCC.

CONCLUSIONS

Our study suggests an inverse association between the dietary intakes of flavonols and lignans and risk of bladder cancer, particularly aggressive UCC.

Intake of fruit and vegetables and risk of bladder cancer: a dose-response meta-analysis of observational studies

BACKGROUND

Observational studies suggest an association between fruit and vegetables intake and risk of bladder cancer, but the results are controversial.

METHODS

We therefore summarized the evidence from observational studies in categorical, linear, and nonlinear, dose-response meta-analysis. Pertinent studies were identified by searching EMBASE and PubMed from their inception to August 2013.

RESULTS

Thirty-one observational studies involving 12,610 cases and 1,121,649 participants were included. The combined rate ratio (RR, 95 % CI) of bladder cancer for the highest versus lowest intake was 0.83 (0.69-0.99) for total fruit and vegetables, 0.81 (0.70-0.93) for total vegetables, 0.77 (0.69-0.87) for total fruit, 0.84 (0.77-0.91) for cruciferous vegetables, 0.79 (0.68-0.91) for citrus fruits, and 0.74 (0.66-0.84) for yellow-orange vegetables. Subgroup analysis showed study design and gender as possible sources of heterogeneity. A nonlinear relationship was found of citrus fruits intake with risk of bladder cancer (P for nonlinearity = 0.018), and the RRs (95 % CI) of bladder cancer were 0.87 (0.78-0.96), 0.80 (0.67-0.94), 0.79 (0.66-0.94), 0.79 (0.65-0.96), and 0.79 (0.64-0.99) for 30, 60, 90, 120, and 150 g/day. A nonlinear relationship was also found of yellow-orange vegetable intake with risk of bladder cancer risk (P for nonlinearity = 0.033). Some evidence of publication bias was observed for fruit, citrus fruits, and yellow-orange vegetables.

CONCLUSION

This meta-analysis supports the hypothesis that intakes of fruit and vegetables may reduce the risk of bladder cancer. Future well-designed studies are required to confirm this finding.

Citrus fruit intake and bladder cancer risk: a meta-analysis of observational studies

Epidemiological studies have investigated the association between citrus fruit and bladder cancer risk; however, the results are inconsistent. To assess these issues, we conducted a meta-analysis of currently available studies. We identified relevant articles by searching the MEDLINE and EMBASE databases. We calculated the summary relative risk (RR) with 95% confidence interval (95% CI) using a random effect model. We included eight case-control studies and six cohort studies in the meta-analysis. There was a significant inverse association between citrus fruit intake and bladder cancer risk in all pooled studies (RR: 0.85; 95% CI, 0.76-0.94) and case-control studies (RR: 0.77; 95% CI, 0.64-0.92), but not in the cohort studies (RR: 0.96; 95% CI, 0.87-1.07). Our results suggest that citrus fruit intake is related to decreased bladder cancer risk. Subsequent well-designed, large prospective studies are needed to obtain better understanding of this relationship.

Fruit and vegetable intakes are associated with lower risk of bladder cancer among women in the Multiethnic Cohort Study

Fruits and vegetables have been examined for their possible effects on the risk of bladder cancer, as they contain numerous nutrients, phytochemicals, and antioxidants with potentially anticarcinogenic properties. In a prospective analysis of 185,885 older adults participating in the Multiethnic Cohort Study, we examined whether the consumption of fruits and vegetables, or of nutrients concentrated in fruits and vegetables, was associated with bladder cancer risk. Cox proportional hazards models were used to calculate HRs and 95% CIs for bladder cancer in relation to dietary intakes. A total of 581 invasive bladder cancer cases (429 men and 152 women) were diagnosed over a mean follow-up period of 12.5 y. In women, total fruits and vegetables [HR = 0.35 (95% CI: 0.22, 0.56); highest vs. lowest quartile], total vegetables [HR = 0.49 (95% CI: 0.29, 0.83)], yellow-orange vegetables [HR = 0.48 (95% CI: 0.30, 0.77)], total fruits [HR = 0.54 (95% CI: 0.34, 0.85)], and citrus fruits [HR = 0.56 (95% CI: 0.34, 0.90)] were inversely associated with the risk of invasive bladder cancer in risk factor-adjusted models. In addition, women with the highest intakes of vitamins A, C, and E; the carotenoids α-carotene, β-carotene, and β-cryptoxanthin; and folate had a lower risk of bladder cancer. For men, no associations for fruits, vegetables, or nutrients were found overall, although inverse associations were observed for vegetable intake among current smokers, and in ethnic-specific analyses, for fruit and vegetable intake among Latinos specifically. Our findings suggest that greater consumption of fruits and vegetables may lower the risk of invasive bladder cancer among women and highlight the need for specific subgroup analyses in future studies.

Fruit and vegetable consumption and risk of aggressive and non-aggressive urothelial cell carcinomas in the European Prospective Investigation into Cancer and Nutrition

BACKGROUND

Many epidemiological studies have examined fruit and vegetable consumption in relation to the risk of urothelial cell carcinoma (UCC) of the bladder, but results are inconsistent. The association between fruit and vegetable consumption and UCC risk may vary by bladder tumour aggressiveness. Therefore, we examined the relation between fruit and vegetable consumption and the risk of aggressive and non-aggressive UCC in the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

After 8.9 years of follow-up, 947UCC were diagnosed among 468,656 EPIC participants. Of these, 421 could be classified as aggressive UCC and 433 as non-aggressive UCC cases. At recruitment, fruit and vegetable consumption was assessed by validated dietary questionnaires. Multivariable hazard ratios were estimated using Cox regression stratified by age, sex and center and adjusted for smoking status, duration and intensity of smoking, and energy intake.

RESULTS

Total consumption of fruits and vegetables was not associated with aggressive UCC nor with non-aggressive UCC. A 25 g/day increase in leafy vegetables and grapes consumption was associated with a reduced risk of non-aggressive UCC (hazard ratio (HR) 0.88; 95%confidence interval (CI) 0.78-1.00 and HR 0.87; 95%CI 0.77-0.98, respectively), while the intake of root vegetables was inversely associated with risk of aggressive UCC (HR 0.87; 95%CI 0.77-0.98).

CONCLUSION

Our study did not confirm a protective effect of total fruit and/or vegetable consumption on aggressive or non-aggressive UCC. High consumption of certain types of vegetables and of fruits may reduce the risk of aggressive or non-aggressive UCC; however chance findings cannot be excluded.

The association of cruciferous vegetables intake and risk of bladder cancer: a meta-analysis

OBJECTIVE

This meta-analysis of cohort and case-control studies was undertaken to evaluate the relationship between cruciferous vegetables intake and risk of bladder cancer.

METHODS

Eligible studies were retrieved via both computer searches and review of references. The summary relative risks (RRs) with 95% confidence interval (CI) for the highest versus the lowest intake of cruciferous vegetables were calculated. Heterogeneity and publication bias were also evaluated.

RESULTS

Five cohort and five case-control studies were included. A significantly decreased risk with bladder cancer was observed in overall cruciferous vegetables intake group (RR = 0.80; 95% CI 0.69-0.92) and subgroup of case-control studies (RR = 0.78; 95% CI, 0.67-0.89), but not in cohort studies (RR = 0.86; 95% CI, 0.61-1.11). No heterogeneity and publication bias were detected across studies.

CONCLUSION

Our findings support that cruciferous vegetables intake was related to the decreased risk of bladder cancer. Because of the limited number of studies, further well-designed prospective studies are needed to explore the protective effect of cruciferous vegetables on bladder cancer.

Minerals and vitamins and the risk of bladder cancer: results from the New Hampshire Study

Objective

Although the effect of fruit and vegetables on the risk of bladder cancer has been widely studied, little is known about their micronutrient components. Our aim was to investigate associations between minerals and vitamins and bladder cancer.

Methods

A case–control study was conducted in New Hampshire, USA. Dietary data were collected from 322 cases and 239 controls using a 121-item food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression adjusting for sex, age, smoking characteristics, and energy intake.

Results

The ORs (95% CI) for highest quartile versus lowest quartile for total intake of vitamin E was 0.66 (0.36–1.20; p trend = 0.09) and 0.49 (0.21–1.17; p trend = 0.13) for dietary phosphorus. The odds of bladder cancer for heavy smokers with the highest total intake of vitamin E, carotenoids, and niacin were 0.58 (0.34–0.99), 0.62 (0.36–1.09), and 0.66 (0.39–1.14), respectively. Higher total intakes of carotenoids, vitamin D, thiamin, niacin, and vitamin E were inversely related to bladder cancer risk among older individuals.

Conclusion

Our findings suggest further investigation of the effect of vitamin E, carotenoids, vitamin D, thiamin, and niacin on bladder cancer risk may be warranted. Future studies should focus on high risk groups such as heavy smokers and older individuals.

Occult HCV infection: an unexpected finding in a population unselected for hepatic disease

Background

Occult Hepatitis C virus (HCV) infection is a new pathological entity characterized by presence of liver disease and absence or very low levels of detectable HCV-RNA in serum. Abnormal values of liver enzymes and presence of replicative HCV-RNA in peripheral blood mononuclear cells are also observed. Aim of the study was to evaluate occult HCV occurrence in a population unselected for hepatic disease.

Methodology/Principal Findings

We chose from previous epidemiological studies three series of subjects (n = 276, age range 40–65 years) unselected for hepatic disease. These subjects were tested for the presence of HCV antibodies and HCV-RNA in plasma and in the peripheral blood mononuclear cells (PBMCs) by using commercial systems. All subjects tested negative for HCV antibodies and plasma HCV-RNA and showed normal levels of liver enzymes; 9/276 patients (3.3%) were positive for HCV-RNA in PBMCs, identifying a subset of subjects with potential occult HCV infection. We could determine the HCV type for 8 of the 9 patients finding type 1a (3 patients), type 1b (2 patients), and type 2a (3 patients).

Conclusions

The results of this study show evidence that occult HCV infection may occur in a population unselected for hepatic disease. A potential risk of HCV infection spread by subjects harbouring occult HCV infection should be considered. Design of prospective studies focusing on the frequency of infection in the general population and on the clinical evolution of occult HCV infection will be needed to verify this unexpected finding.

Dietary intake of vegetables and fruits and the modification effects of GSTM1 and NAT2 genotypes on bladder cancer risk

We analyzed the association between intakes of vegetables and fruits as defined by the U.S. Department of Agriculture pyramid food groups and bladder cancer risk using data collected in a large case-control study. The study included 884 histologically confirmed bladder cancer cases and 878 healthy controls matched to cases by age (+/-5 years), gender, and ethnicity. Significant inverse associations were observed for intakes of total vegetables, cruciferous vegetables, orange vegetables, dark green vegetables, and bladder cancer risk. Compared with those in the lowest quartile of total vegetable intake, the odds ratios for the 2nd, 3rd, and 4th quartiles of total vegetable intake were 0.84 [95% confidence interval (95% CI), 0.64-1.10], 0.71 (95% CI, 0.54-0.95), and 0.67 (95% CI, 0.50-0.90), respectively (P for trend = 0.004). Compared with those in the lowest quartile, those in the highest quartile of cruciferous vegetable intake had an odds ratio of 0.69 (95% CI, 0.52-0.92; P for trend = 0.001) and those in the highest quartile of orange vegetable intake had an odds ratio of 0.68 (95% CI, 0.52-0.91; P for trend = 0.006). Furthermore, the protective effect of cruciferous vegetables was more evident in subjects carrying GSTM1-null (odds ratio, 0.43; 95% CI, 0.25-0.73 for the 4th quartile of intake) and NAT2-slow genotypes (odds ratio, 0.56; 95% CI, 0.33-0.97 for the 4th quartile of intake). No association was observed for intakes of total fruits or citrus fruits. Our data strongly support that high vegetable consumption, especially cruciferous vegetable intake, may protect against bladder cancer and that genetic variants of GSTM1 and NAT2 may modify the association.

Nutrition, total fluid and bladder cancer

Bladder cancer is a major health concern for older males in Western populations. About 30 years ago there was a suggestion that nutrition may have a role in the aetiology of the disease. Although the literature has been accumulating since then, owing to heterogeneity between studies results have often been inconsistent and unclear. The aim of this paper was to present an updated summary of the scientific evidence on the association between nutrition, total fluid intake and bladder cancer. A search of computerized databases, PubMed, ISI, Embase and Cochrane Library, was conducted to identify all epidemiological studies published between 1966 and October 2007. The level of scientific evidence for the various nutritional factors and total fluid intake was ranked according to the number of studies reporting a statistically significant association and the existence of mechanistic evidence. The levels of association were based on a ranking of statistically significant relative risks. Fruit and yellow-orange vegetables, particularly carrots and selenium, are probably associated with a moderately reduced risk of bladder cancer. Citrus fruits and cruciferous vegetables were also identified as having a possible protective effect. Possible risk factors are salted and barbecued meat, pork, total fat, pickled vegetables, salt, soy products, spices and artificial sweeteners. No clear association could be determined for beef, eggs, processed meats and total fluid intake. In conclusion, specific fruit and vegetables may act to reduce the risk of bladder cancer. Future studies on bladder cancer should investigate the effect of food categorization, amount and gender.