Milk Products and Bladder Cancer
According to the World Cancer Research Fund International, the authority on the role of diet and cancer, no conclusions can be drawn at this time regarding a possible association between milk products and bladder cancer due to limited evidence. However, studies have suggested that there is a reduced risk of bladder cancer associated with milk product intake.
Basic Facts on Bladder Cancer1
Every year, there are about 8,000 new cases of bladder cancer in Canada. As with most cancers, there is no single cause of bladder cancer, but there are risk factors for its development. These include the following:
- Smoking (the most common risk factor)
- Age—particularly after 65 years
- Occupational exposure to chemicals
- Chronic bladder irritation
- Family history of bladder cancer
- Personal history of bladder cancer
The 2015 Continuous Update Project (CUP) reportissued by theWorld Cancer Research Fund International/American Institute for Cancer Research indicates that there is limited evidence on the association between milk products (milk, cheese, yogurt) and bladder cancer, such that no conclusion can be drawn.2
In a 2016 systematic review of meta-analyses, the authors concluded that milk consumption was associated with a reduced risk of bladder cancer.3
In another systematic review of meta-analyses, also published in 2016, the association between modifiable risk factors (including dietary factors) and the risk of bladder cancer was investigated.4 The authors identified the meta-analysis by Mao et al.5 as being one of the most comprehensive scientific studies conducted on the relationship between dairy products and bladder cancer. It consisted of 19 cohort and case-control studies with a total of 7,867 bladder cancer cases.
- Higher total milk consumption was associated with a 16% risk reduction in bladder cancer;
- Fermented milk was associated with a 31% risk reduction in bladder cancer;
- There was no association between cheese or butter and bladder cancer risk;
- Intake of whole milk appeared to increase the risk of bladder cancer based on two included studies.
Calcium and vitamin D
To date, few studies have investigated the role that calcium or vitamin D may play in bladder cancer.
While intracellular calcium favourably influences cell growth and apoptosis of epithelial cells, calcium can have both beneficial and harmful effects on carcinogenesis at the cellular level, depending on the cell type.6
Vitamin D is also thought to be protective against cancer in many organs due to its anti-proliferative effect. Higher intakes of vitamin D have been associated with reduced bladder cancer risk in the elderly.6
Lactic acid bacteria
Fermented or cultured milk products, such as yogurt, and some cheeses are a source of lactic acid bacteria. A few animal studies, as well as a randomized trial among humans, have shown that Lactobacillus supplementation may prevent bladder carcinogenesis.6,7
Limited evidence from scientific literature suggests that the consumption of milk and milk products, especially fermented or cultured milk products, may decrease the risk of bladder cancer. However, more studies are needed for conclusive answers.
While calcium, vitamin D and lactic acid bacteria may have beneficial effects against bladder cancer, more mechanistic studies are needed to investigate their anti-cancer properties.
- Canadian Cancer Society. 2016. What is bladder cancer? www.cancer.ca. Accessed August 2, 2016.
- World Cancer Research Fund International/American Institute for Cancer Research. 2015. Continuous Update Project report: Diet, nutrition, physical activity and bladder cancer. www.wcrf.org. Accessed August 2, 2016.
- Fardet A and Boirie Y. Associations between food and beverage groups and major diet-related chronic diseases: an exhaustive review of pooled/meta-analyses and systematic reviews. Nutr Rev 2014;72:741-762.
- Al-Zalabani AH et al. Modifiable risk factors for the prevention of bladder cancer: a systematic review of meta-analyses. Eur J Epidemiol 2016. doi: 10.1007/s10654-016-0138-6.
- Mao QQ et al. Milk consumption and bladder cancer risk: a meta-analysis of published epidemiological studies. Nutr Cancer 2011;63:1263-1271.
- Lampe JW. Dairy products and cancer. J Am Coll Nutr 2011;30:464S-470S.
- Feyisetan O et al. Probiotics, dendritic cells and bladder cancer. BJU Int 2012;109:1594-1597.