A study examined whether bladder cancer risk factors were significantly increased with increased consumption of refined carbohydrates and foods that increase glycemic load.
Bladder cancer is the fifth most common cancer in Canada with an estimated 9,000 Canadians diagnosed with the disease annually.1 While smoking is known to be a major risk factor in the development of bladder cancer that accounts for 30-50% of the cases,2 metabolic syndrome and type 2 diabetes, can also increase bladder cancer risk factors.3,4 Hyperinsulinemia (high levels of insulin in the blood) and hyperglycemia (high levels of sugar in the blood) may play a major role in the initiation and progress of bladder cancer. These data indicate the importance of lifestyle factors in the development of the disease.
Foods with high glycemic index and glycemic load increase blood glucose to greater levels than low glycemic foods with equivalent amounts of carbohydrates. Glycemic index is a measure of the amount of sugar in the blood. Glycemic load is a measure that takes into consideration both the amount and the quality of the carbohydrates in a meal. High glycemic index foods have been shown to be linked with a greater risk of bladder cancer in North American populations.5,6
A new study examined the association between high glycemic index and glycemic load foods and bladder cancer in the Italian population. The study published its findings recently in the British Journal of Nutrition.7 The study included 578 individuals with confirmed bladder cancer. The control group consisted of 608 individuals who were hospitalized for other unrelated acute conditions. Information on age, education, lifestyle, and dietary habits were obtained using questionnaires. The dietary questionnaire was used to calculate total energy and carbohydrate intake.
The dietary information was then used to calculate the average daily glycemic index and glycemic load for each participant. Odds ratios were determined to assess the extent of the association between carbohydrate intake, glycemic index, glycemic load, and bladder cancer. The model took into account confounding factors such as smoking status, alcohol consumption, educational status, abdominal obesity, and total energy intake, which could influence the results.
The study found that, compared to non-smokers, heavy smokers had a seven-fold higher risk of developing bladder cancer. Additionally, patients with abdominal obesity were at a higher risk of developing bladder cancer, but educational status, alcohol consumption, and total energy intake were not linked to disease development.
As for the link with carbohydrate consumption, there was no link between total available carbohydrates or glycemic index and bladder cancer. However, there was a significant association between glycemic load and disease risk. Additionally, increased bread and pasta consumption were associated with bladder cancer risk factors. The association between pasta consumption and disease risk was statistically significant in men only. The study also found that the effect of elevated glycemic load on bladder cancer risk factors was more pronounced in individuals whose vegetable consumption was below the median level for the entire group.
Overall, this study confirms the findings of previous studies about the association of bladder cancer with the consumption of large quantities of refined carbohydrates and foods with a high glycemic load. These findings are also in line with the prevailing wisdom about the advantages of consuming high fibre foods with a low glycemic index and adopting a diet rich in vegetables.
Written by Usha B. Nair, Ph.D.
(1) Bladder Cancer Canada. Facing Bladder Cancer: Bladder Cancer Facts. https://bladdercancercanada.org/en/bladder-cancer-facts/. Accessed: October 15, 2017.
(2) Freedman ND, Silverman DT, Hollenbeck AR, Schatzkin A, Abnet CC. Association between smoking and risk of bladder cancer among men and women. JAMA. 2011 Aug 17;306(7):737-45. doi: 10.1001/jama.2011.1142. Erratum in: JAMA. 2011 Nov 23;306(20):2220. PubMed PMID: 21846855; PubMed Central PMCID: PMC3441175.
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(4) Zhu Z, Zhang X, Shen Z, Zhong S, Wang X, Lu Y, Xu C. Diabetes mellitus and risk of bladder cancer: a meta-analysis of cohort studies. PLoS One. 2013;8(2):e56662. doi: 10.1371/journal.pone.0056662. Epub 2013 Feb 20. PubMed PMID: 23437204; PubMed Central PMCID: PMC3577653.
(5) George SM, Mayne ST, Leitzmann MF, Park Y, Schatzkin A, Flood A, Hollenbeck A, Subar AF. Dietary glycemic index, glycemic load, and risk of cancer: a prospective cohort study. Am J Epidemiol. 2009 Feb 15;169(4):462-72. doi: 10.1093/aje/kwn347. Epub 2008 Dec 18. PubMed PMID: 19095757; PubMed Central PMCID: PMC2726642.(6) Hu J, La Vecchia C, Augustin LS, Negri E, de Groh M, Morrison H, Mery L; Canadian Cancer Registries Epidemiology Research Group. Glycemic index, glycemic load and cancer risk. Ann Oncol. 2013 Jan;24(1):245-51. doi: 10.1093/annonc/mds235. Epub 2012 Jul 25. PubMed PMID: 22831983.
(7) Augustin LSA, Taborelli M, Montella M, Libra M, La Vecchia C, Tavani A, Crispo A, Grimaldi M, Facchini G, Jenkins DJA, Botti G, Serraino D, Polesel J. Associations of dietary carbohydrates, glycaemic index and glycaemic load with risk of bladder cancer: a case-control study. Br J Nutr. 2017 Oct 9:1-8. doi: 10.1017/S0007114517002574. [Epub ahead of print] PubMed PMID: 28990544.