High consumption of red meat and/or fried meats such as chicken or fish may increase the risk of bladder cancer, especially among individuals who already carry a genetic risk.
Bladder cancer is diagnosed in as many as 60,000 individuals annually in the United States. It is much more common in elderly individuals. Bladder cancer has high cure rates if detected and treated early; however, these cure rates fall dramatically once the cancer has spread to different sites in the body. As with all types of cancer, the best “treatment” of bladder cancer is to prevent its occurrence in the first place. Thus, researchers continue to evaluate potential risk factors for the disease.
It has been suspected that consumption of meat may increase risk for bladder cancer for many years. More specifically, cooking technique and compounds that are related to the processing of meat are being investigated as potential risk factors. These compounds include nitrate and nitrite, which are added to processed meat for preservation and enhancement of color and flavor.
Researchers associated with the National Institutes of Health and AARP investigated the association between meat and meat components and bladder cancer risk. Information on lifestyle and dietary habits was collected from over 300,000 individuals in the United States. At a follow-up of eight years, 854 participants had been diagnosed with bladder cancer.
When looking at broad categories of meat (red, white, or processed), there was no clear link between meat intake and bladder cancer risk. There was, however a suggestion of an increased risk of bladder cancer among those who consumed the highest level of red processed meat, as well as among those who consumed the highest level of red meat cold cuts.
Participants with the highest level of dietary nitrite from all sources (not only processed meat) had a 28% increased risk of bladder cancer compared with those with the lowest intake. Risk was increased to a similar extent (29%) among those with the highest intake of nitrate plus nitrite from processed meat. This latter finding was of borderline statistical significance, suggesting that it could have occurred by chance alone.
The researchers concluded that these findings provided “modest support” for a link between bladder cancer and total dietary nitrite and nitrate plus nitrite from processed meat. Further study into these associations is warranted.1
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High-temperature cooking methods—such as grilling, charring, frying, and barbecuing—have been found to generate heterocyclic amines (HCAs), which are carcinogenic compounds that increase cancer risk. Researchers from the M. D. Anderson Cancer Center conducted a study that included 884 patients with bladder cancer and 878 control subjects. After collecting dietary data from all subjects, the researchers found that individuals who reported eating a lot of beef, pork, bacon, fried chicken, and fried fish had a higher risk of developing bladder cancer. Red meats cooked at the medium level conferred 1.46 times the level of those cooked rare, while meats cooked to well-done levels conferred 1.94 times the risk.
The researchers also observed a “joint effect” when individuals with certain genetic variants in the pathways related to HCA metabolism consumed high quantities of red meat. Individuals who have these genetic variations are 4.74 times as likely to develop bladder cancer when they eat a lot of red meat.
The researchers concluded that red meat intake increases the risk of bladder cancer, especially when combined with other factors such as high-temperature cooking or genetic predisposition.
- Ferrucci LM, Sinha R, Ward MH, et al. Meat and components of meat and the risk of bladder cancer in the NIH-AARP Diet and Health Study. Cancer [early online publication]. August 2, 2010.
- Lin J, Wang J, Grossman HB, et al. Red meat and heterocyclic amine intake, metabolic pathway genes, and bladder cancer risk. Presented at the Annual Meeting of the American Association for Cancer Research, April 17-21, 2001. Washington, D.C. Abstract #2825.