








































This is an open access article under the terms of a license that permits non-commercial use, provided the original work is properly cited.  
© 2022 The Authors. Société Internationale d'Urologie Journal, published by the Société Internationale d'Urologie, Canada.

Key Words Competing Interests Article Information

Urinary bladder neoplasm, diet, vegetarian, 
systematic review

None declared.

Funding: S.L. is supported by the Prostate 
Cancer Foundation, and a generous donation 
from Patricia and Michael Berns.

Received on October 11, 2021 
Accepted on March 15, 2022 
This article has been peer reviewed.

Soc Int Urol J. 2022;3(4):240–244

DOI: 10.48083/GBMA2534

240 SIUJ  •  Volume 3, Number 4  •  July 2022 SIUJ.ORG

REVIEW

A Systematic Review of Plant-Based Diet and 
Bladder Cancer: A Call for Further Research

Jacob Taylor,1 Natasha Gupta,1,2 Jaime Blanck,3 Stacy Loeb1,2

1 Department of Urology, New York University Langone Health, New York, United States  2 Department of Population Health, New York University Langone Health and 
Manhattan Veteran Affairs, New York, United States  3 Johns Hopkins Welch Medical Library, Johns Hopkins University, Baltimore, United States

Abstract

The relationship between plant-based dietary patterns and bladder cancer has not been extensively studied.  
Our objective was to perform a systematic review of the relationship between plant-based diets and bladder cancer risk 
and/or outcomes. We searched the literature for all relevant papers published before October 2020. Of 74 identified 
records, only 2 references were included in the final qualitative analysis. These publications found that vegetarian 
diets are associated with a lower risk of bladder cancer diagnosis. We did not identify any studies investigating the 
impact of plant-based dietary patterns on outcomes for individuals diagnosed with bladder cancer, which represents 
an important area for further study.

Introduction 

Previous studies have examined the relationship between specific foods and bladder cancer risk. A systematic review 
of modifiable risk factors for bladder cancer reported that consuming more fruits and vegetables was associated with a 
decreased risk, whereas the consumption of processed meat was associated with an increased risk of bladder cancer[1].

Nutritional epidemiology is shifting toward evaluation of dietary patterns[2]. A previous systematic review 
suggested that the Mediterranean diet is associated with lower bladder cancer risk, while the Western diet is associ-
ated with increased risk[3]. Plant-based diets have become increasingly popular, but relatively little is known about 
their relationship to bladder cancer risk and/or outcomes. Therefore, our objective was to perform a systematic review 
of the relationship between plant-based diets (eg, vegetarian or vegan) and bladder cancer risk and/or outcomes.

Materials and Methods
The systematic review was conducted according to the European Association of Urology methodology, beginning 
with formulating the research question and writing the protocol, which was registered with PROSPERO (ID 
CRD42020214023). We then conducted a search of PubMed, Embase, Cochrane, Scopus, Web of Science, and AMED 
for all relevant publications up to October 2020. The search terms were vegetarian or vegan diets and MeSH term 
variations for bladder cancer or urothelial carcinoma (see appendix for details). Of 74 identified records, 34 were 
screened after duplicates were removed (Figure 1). Only 2 references were included in the final qualitative analysis.

The quality of evidence was assessed using the criteria outlined by Hawker et al.[4], which use 9 question domains 
with scores ranging from “very poor” (1) to “good” (4), with 36 being the highest score. If multiple publications come 
from a single study, a composite score is reported including information from all publications.

http://SIUJ.org
https://orcid.org/0000-0003-2190-7309
mailto:Jacob.taylor.mail%40gmail.com?subject=SIUJ
https://orcid.org/0000-0003-2782-415X
https://orcid.org/0000-0002-7235-0857
https://orcid.org/0000-0003-3933-9207


Results
The first publication by Key et al. reported on a large 
prospective cohort study of 61  566 British men and 
women[5]. Participants completed semi-quantitative 
food frequency questionnaires and were followed 
for an average of 12.2 years and were divided into  
3 categories: meat eaters, fish eaters (did not eat meat but 
did eat fish), and vegetarians (did not eat meat or fish). 
The study population included > 20 000 vegetarians. 
Multivariable models were performed to examine cancer 
risk after adjustment for potential confounders such as 
smoking and physical activity. Compared with meat 
eaters, fish eaters had no difference in risk of bladder 
cancer (RR 0.81; 95% CI 0.36–1.81), but vegetarians 
had a significantly lower risk of bladder cancer (RR 
0.47; 95% CI 0.25–0.89). A follow-up analysis by Key et 
al. similarly found a significantly lower risk of bladder 
cancer among vegetarians compared with meat eaters  

(R R 0.62; 95% CI 0.38–0.99), although this was 
attenuated after adjustment for body mass index[6]. 
Overall, the composite quality rating from both 
publications was 36, a high-quality rating.

Discussion
Overall, our systematic review identif ied only 2 
publications from a single prospective UK cohort study 
that specifically evaluated plant-based dietary patterns 
and bladder cancer. The limited available evidence 
suggests a vegetarian diet might be protective against 
bladder cancer. These findings are not surprising in 
light of previous studies suggesting an association 
between higher fruit and vegetable consumption and 
lower bladder cancer risk, whereas consumption of 
meat products has been linked with higher risk[1,7]. 
We did not identify any studies that examined plant-
based diets with outcomes among patients diagnosed 

*Texts excluded due to lack of dietary or outcome data.

FIGURE 1. 

PRISMA flow chart

Records identi�ed through 
database searching

(n = 74)

In
cl
ud
ed

S
cr
ee
ni
ng

Records after duplicates removed
(n = 34)

Records screened
(n = 34)

Full-text articles assessed 
for eligibility

(n = 10)

Studies included in qualitative 
synthesis

(n = 2)

Records excluded
(n = 24)

Full-text articles excluded, 
with reasons

(n = 8)*

Additional records identi�ed 
through other sources

(n = 0)

es

El
ig
ib
il
it
y

Id
en
ti
�c
at
io
n

241SIUJ.ORG SIUJ  •  Volume 3, Number 4  •  July 2022

A Systematic Review of Plant-Based Diet and Bladder Cancer: A Call for Further Research

http://SIUJ.org


with bladder cancer, representing an important area for 
future research. Although the quantity of evidence is 
quite small, the quality of evidence that does exist is high 
based on these 2 publications.

The association between diet and risk of cancer has 
been explored in almost every cancer type. For instance, 
Vieira et al., in a 2017 systematic review, found a 12% 
increased risk of colorectal cancer for each 100g/day 
consumption of red and processed meat[8]. There are 
many potential explanations for this association, includ-
ing the generation of oxidative stress from heme iron 
and the carcinogenic effect of N-nitroso compounds 
and heterocyclic amines[9]. These same compounds 
may incite the development of bladder cancer, and 
decreasing the consumption and formation of these 
toxic compounds could decrease the dwell time of 
these carcinogens in the urine. A plant-based diet may 
provide greater antioxidant protection against free radi-

cal damage[10]. For instance, selenium, a known anti-
oxidant, was found to be inversely related to bladder 
cancer risk in a meta-analysis of 7 studies[11]. Additional 
prospective studies are warranted to further explore the 
impact of plant-based dietary patterns in bladder cancer.

Conclusion
Given the importance of identifying modifiable factors 
that can affect bladder cancer risk and outcomes, our 
study highlights a great need for more research into 
the impact of plant-based diets. Most previous studies 
have focused on individual dietary components rather 
than dietary patterns. Observational data suggest that 
vegetarian diets may be associated with a lower risk of 
bladder cancer; however, we did not identify any studies 
investigating the impact of plant-based dietary patterns 
on oncologic or functional outcomes for individuals 
already diagnosed with bladder cancer, which represents 
an important area for further study.

References

1. Al-Zalabani AH, Stewart KF, Wesselius A, Schols AM, Zeegers MP. 
Modifiable risk factors for the prevention of bladder cancer: a systematic 
review of meta-analyses. Eur J Epidemiol.2016;31(9):811–851. doi: 
10.1007/s10654-016-0138-6

2. Cespedes EM, Hu FB. Dietary patterns: from nutritional epidemiologic 
analysis to national guidelines. Am J Clin Nutr.2015;101(5):899–900. 
doi: 10.3945/ajcn.115.110213. Epub 2015 Apr 1.

3. Dianatinasab M, Forozani E, Akbari A, Azmi N, Bastam D, Fararouei M, 
et al. Dietary patterns and risk of bladder cancer: a systematic review 
and meta-analysis. BMC Public Health.2022;22(1):73. doi:10.1186/
s12889-022-12516-2

4. Hawker S, Payne S, Kerr C, Hardey M, Powell J. Apprasing the 
evidence: reviewing disparate data systematically. Qual Health 
Res.2002;12(9):1284–1299. doi: 10.1177/1049732302238251

5. Key TJ, Appleby PN, Spencer EA, Travis RC, Allen NE, Thorogood M, 
et al. Cancer incidence in British vegetarians. Br J Cancer.2009;101(1): 
192–197. doi: 10.1038/sj.bjc.6605098. Epub 2009 Jun 16.

6. Key TJ, Appleby PN, Crowe FL, Bradbury KE, Schmidt JA, Travis RC. 
Cancer in British vegetarians: updated analyses of 4998 incident 
cancers in a cohort of 32,491 meat eaters, 8612 fish eaters, 18,298 
vegetarians, and 2246 vegans. Am J Clin Nutr.2014;100 (Suppl. 
1)1:378S–385S. doi: 10.3945/ajcn.113.071266. Epub 2014 Jun 4.

7. Michaud DS, Holick CN, Giovannucci E, Stampfer MJ. Meat intake 
and bladder cancer risk in 2 prospective cohort studies. Am J Clin 
Nutr.2006;84(5):1177–1183. doi: 10.1093/ajcn/84.5.1177

8. Vieira AR, Abar L, Chan DSM, Vingeliene S, Polemiti E, Stevens C, et al. 
Foods and beverages and colorectal cancer risk: a systematic review 
and meta-analysis of cohort studies, an update of the evidence of the 
WCRF-AICR Continuous Update Project. Ann Oncol.2017;28(8):1788–
1802. doi: 10.1093/annonc/mdx171

9. Song M, Garrett WS, Chan AT. Nutrients, foods, and colorectal 
cancer prevention. Gastroenterology.2015;148(6):1244-1260 e16. doi: 
10.1053/j.gastro.2014.12.035. Epub 2015 Jan 6.

10. World Cancer Research Fund/American Institute for Cancer Research. 
Continuous Update Project Expert Report 2018. Diet, nutrition, physical 
activity and bladder cancer. Available at: https://www.wcrf.org/
wp-content/uploads/2021/02/Bladder-cancer-report.pdf. Accessed 
March 16, 2022.

11. Amaral A, Cantor K, Silverman D, Malats N. Selenium and bladder 
cancer risk: a meta-analysis. Cancer Epidemiol Biomarkers 
Prev.2010;19(9):2407-2415. DOI: 10.1158/1055-9965.EPI-10-0544

242 SIUJ  •  Volume 3, Number 4  •  July 2022 SIUJ.ORG

 REVIEW

http://SIUJ.org


Embase
26 citations
(“bladder cancer”/exp OR “bladder adenocarcinoma” 
OR  “ bl a dd er  a d eno c a rc i nom a”  OR  “ bl a dd er 
cancerogenesis” OR “ bladder carcinogenesis” OR 
“ bladder carcinoma” OR “ bladder diver ticu lum 
carcinoma” OR “ bladder metastasis” OR “ bladder 
cancer” OR “transitional cell cancer” OR “bladder 
carcinogen” OR “urinary bladder metastasis” OR 
“urothelial cancer” OR “urothelial carcinoma” OR 
“vesical cancer” OR “vesical carcinomanesis” OR 
“vesical carcinomatosis” OR “Bladder Neoplasm” 
OR “Bladder Neoplasms” OR “Bladder Tumors” OR 
“Bladder Tumor” OR “Malignant Tumor of Urinary 
Bladder” OR “Cancer of the Bladder” OR “Bladder 
Cancers” OR “transitional cell carcinoma”/exp OR 
“transitional cell cancer” OR “transitional cell cancers” 
OR “transitional cell carcinoma” OR “transitional 
cell carcinomas” OR “transitional cell tumor” OR 
“transitional cell tumors” OR “transitional cell tumour” 
OR “transitional cell tumours” OR “urothelial cancer” 
OR “urothelial cancers” OR “urothelial carcinoma” OR 
“urothelial carcinomas” OR “urothelial cell cancer” OR 
“urothelial cell cancers” OR “urothelial cell carcinoma” 
OR “urothelial cell carcinomas”) AND (“vegetarian”/
de OR “lactoovovegetarian”/exp OR “lactovegetarian”/
exp OR “vegan”/exp OR “vegetarian diet”/de OR 
“fruitarian diet”/exp OR “lactovegetarian diet”/exp 
OR “ovovegetarian diet”/exp OR “vegan diet”/exp 
OR “plant based” OR “plant-based” OR “vegan” OR 
“veganism” OR “vegans” OR “vegetable based” OR 
“vegetarian” OR “vegetarianism” OR “vegetarians’ OR 
lactoovovegetarian* OR lactovegetarian*)

PubMed
10 citations
(“Urinary Bladder Neoplasms”[MeSH] OR “bladder 
adenocarcinoma” OR “bladder adenocarcinoma” OR 
“bladder cancerogenesis” OR “bladder carcinogenesis” 
OR “bladder carcinoma” OR “bladder diverticulum 
carcinoma” OR “ bladder metastasis” OR “ bladder 
cancer” OR “transitional cell cancer” OR “bladder 
carcinogen” OR “urinary bladder metastasis” OR 
“urothelial cancer” OR “urothelial carcinoma” OR 
“vesical cancer” OR “vesical carcinomanesis” OR 
“vesical carcinomatosis” OR “Bladder Neoplasm” 
OR “Bladder Neoplasms” OR “Bladder Tumors” OR 
“Bladder Tumor” OR “Malignant Tumor of Urinary 
Bladder” OR “Cancer of the Bladder” OR “Bladder 
Cancers” OR “Carcinoma, Transitional Cell”[MeSH] OR 
“transitional cell cancer” OR “transitional cell cancers” 
OR “transitional cell carcinoma” OR “transitional 
cell carcinomas” OR “transitional cell tumor” OR 
“transitional cell tumors” OR “transitional cell tumour” 
OR “transitional cell tumours” OR “urothelial cancer” 
OR “urothelial cancers” OR “urothelial carcinoma” 
OR “urot helia l carcinomas” OR “urot helia l cell 
cancer” OR “urothelial cell cancers” OR “urothelial 
cell carcinoma” OR “urothelial cell carcinomas”) AND 
(“Vegetarians”[MeSH] OR “Diet, Vegetarian”[MeSH] 
OR “Vegans”[MeSH] OR “Diet, Vegan”[MeSH] OR 
“plant based”[tw] OR “plant-based”[tw] OR “vegan”[tw] 
OR “veganism”[tw] OR “vegans”[tw] OR “vegans”[tw] 
OR “vegetable based ”[t w] OR “vegeta ria n”[t w] 
OR “vegetarianism”[tw] OR “vegetarians”[tw] OR 
lactoovovegetarian*[tw] OR lactovegetarian*[tw])

Cochrane
2 results
([mh “Urinary Bladder Neoplasms”] OR “ bladder 
adenocarcinoma” OR “bladder adenocarcinoma” OR 
“bladder cancerogenesis” OR “bladder carcinogenesis” 
OR “bladder carcinoma” OR “bladder diverticulum 
carcinoma” OR “ bladder metastasis” OR “ bladder 
cancer” OR “transitional cell cancer” OR “bladder 
carcinogen” OR “urinary bladder metastasis” OR 
“urothelial cancer” OR “urothelial carcinoma” OR 
“vesical cancer” OR “vesical carcinomanesis” OR 
“vesical carcinomatosis” OR “Bladder Neoplasm” 
OR “Bladder Neoplasms” OR “Bladder Tumors” OR 
“Bladder Tumor” OR “Malignant Tumor of Urinary 
Bladder” OR “Cancer of the Bladder” OR “Bladder 
Cancers” OR [mh “Carcinoma, Transitional Cell”] OR 

APPENDIX 1. 

Search term strategy

Search Summary 

Embase 26

PubMed 10

Cochrane 2

Scopus 24

Web of Science 12

AMED 2

Total found 74

Duplicates 40

Grand Total 34

243SIUJ.ORG SIUJ  •  Volume 3, Number 4  •  July 2022

A Systematic Review of Plant-Based Diet and Bladder Cancer: A Call for Further Research

http://SIUJ.org


“transitional cell cancer” OR “transitional cell cancers” 
OR “transitional cell carcinoma” OR “transitional 
cell carcinomas” OR “transitional cell tumor” OR 
“transitional cell tumors” OR “transitional cell tumour” 
OR “transitional cell tumours” OR “urothelial cancer” 
OR “urothelial cancers” OR “urothelial carcinoma” 
OR “urot helia l carcinomas” OR “urot helia l cell 
cancer” OR “urothelial cell cancers” OR “urothelial 
cell carcinoma” OR “urothelial cell carcinomas”) 
AND ([mh “Vegetarians”] OR [mh “Diet, Vegetarian”] 
OR [mh “Vegans”] OR [mh “Diet, Vegan”] OR “plant 
based” OR “plant-based” OR “vegan” OR “veganism” 
OR “vegans” OR “vegans” OR “vegetable based” OR 
“vegetarian” OR “vegetarianism” OR “vegetarians” OR 
lactoovovegetarian* OR lactovegetarian*)

Scopus
24 results
TITLE-ABS-K EY((“ bladder adenocarcinoma” OR 
“bladder adenocarcinoma” OR “bladder cancerogenesis” 
OR “bladder carcinogenesis” OR “bladder carcinoma” 
OR “bladder diverticulum carcinoma” OR “bladder 
metastasis” OR “ bladder cancer” OR “transitional 
cell cancer” OR “bladder carcinogen” OR “urinary 
bladder metastasis” OR “urot helia l cancer” OR 
“urothelial carcinoma” OR “vesical cancer” OR “vesical 
carcinomanesis” OR “vesical carcinomatosis” OR 
“Bladder Neoplasm” OR “Bladder Neoplasms” OR 
“Bladder Tumors” OR “Bladder Tumor” OR “Malignant 
Tumor of Urinary Bladder” OR “Cancer of the Bladder” 
OR “Bladder Cancers” OR “transitional cell cancer” 
OR “transitional cell cancers” OR “transitional cell 
carcinoma” OR “transitional cell carcinomas” OR 
“transitional cell tumor” OR “transitional cell tumors” 
OR “transitional cell tumour” OR “transitional cell 
tumours” OR “urothelial cancer” OR “urothelial 
cancers” OR “urothelial carcinoma” OR “urothelial 
carcinomas” OR “urothelial cell cancer” OR “urothelial 
cell cancers” OR “urothelial cell carcinoma” OR 
“urothelial cell carcinomas”) AND (“plant based ” 
OR “plant-based” OR “vegan” OR “veganism” OR 
“vegans” OR “vegans” OR “vegetable based ” OR 
“vegetarian” OR “vegetarianism” OR “vegetarians” OR 
lactoovovegetarian* OR lactovegetarian*))

Web of Science
12 results
T S = (“ bl adder  adeno c a rc i nom a”  OR  “ bl adder 
adenocarcinoma” OR “bladder cancerogenesis” OR 
“ bladder carcinogenesis” OR “ bladder carcinoma” 
OR “bladder diverticulum carcinoma” OR “bladder 
metastasis” OR “ bladder cancer” OR “transitional 

cell cancer” OR “bladder carcinogen” OR “urinary 
bladder metastasis” OR “urot helia l cancer” OR 
“urothelial carcinoma” OR “vesical cancer” OR “vesical 
carcinomanesis” OR “vesical carcinomatosis” OR 
“Bladder Neoplasm” OR “Bladder Neoplasms” OR 
“Bladder Tumors” OR “Bladder Tumor” OR “Malignant 
Tumor of Urinary Bladder” OR “Cancer of the Bladder” 
OR “Bladder Cancers” OR “transitional cell cancer” 
OR “transitional cell cancers” OR “transitional cell 
carcinoma” OR “transitional cell carcinomas” OR 
“transitional cell tumor” OR “transitional cell tumors” 
OR “transitional cell tumour” OR “transitional cell 
tumours” OR “urothelial cancer” OR “urothelial 
cancers” OR “urothelial carcinoma” OR “urothelial 
carcinomas” OR “urothelial cell cancer” OR “urothelial 
cell cancers” OR “urothelial cell carcinoma” OR 
“urothelial cell carcinomas”) AND TS=(“plant based” 
OR “plant-based” OR “vegan” OR “veganism” OR 
“vegans” OR “vegans” OR “vegetable based ” OR 
“vegetarian” OR “vegetarianism” OR “vegetarians” OR 
lactoovovegetarian* OR lactovegetarian*)

AMED
No results found
(Bladder neoplasms/ OR “bladder adenocarcinoma” OR 
“bladder adenocarcinoma” OR “bladder cancerogenesis” 
OR “bladder carcinogenesis” OR “bladder carcinoma” 
OR “bladder diverticulum carcinoma” OR “bladder 
metastasis” OR “ bladder cancer” OR “transitional 
cell cancer” OR “bladder carcinogen” OR “urinary 
bladder metastasis” OR “urot helia l cancer” OR 
“urothelial carcinoma” OR “vesical cancer” OR “vesical 
carcinomanesis” OR “vesical carcinomatosis” OR 
“Bladder Neoplasm” OR “Bladder Neoplasms” OR 
“Bladder Tumors” OR “Bladder Tumor” OR “Malignant 
Tumor of Urinary Bladder” OR “Cancer of the Bladder” 
OR “Bladder Cancers” OR “transitional cell cancer” 
OR “transitional cell cancers” OR “transitional cell 
carcinoma” OR “transitional cell carcinomas” OR 
“transitional cell tumor” OR “transitional cell tumors” 
OR “transitional cell tumour” OR “transitional cell 
tumours” OR “urothelial cancer” OR “urothelial 
cancers” OR “urothelial carcinoma” OR “urothelial 
carcinomas” OR “urothelial cell cancer” OR “urothelial 
cell cancers” OR “urothelial cell carcinoma” OR 
“urothelial cell carcinomas”) AND (Vegetarianism/ OR 
Diet vegetarian/ OR “plant based” OR “plant-based” OR 
“vegan” OR “veganism” OR “vegans” OR “vegans” OR 
“vegetable based” OR “vegetarian” OR “vegetarianism” 
OR “veget a r ia ns” OR lac toovoveget a r ia n* OR 
lactovegetarian*)

244 SIUJ  •  Volume 3, Number 4  •  July 2022 SIUJ.ORG

 REVIEW

http://SIUJ.org



