Consumption of red and processed meats has already been linked to increased risk of developing several types of cancer. Animal studies have revealed a number of compounds in meat that might account for this association. These compounds include heterocyclic amines, polycyclic aromatic hydrocarbons, and N-nitroso. Also added to meats are nitrate and nitrite compounds; the known precursors to N-nitroso compounds.
Lead researcher, Amanda J. Cross, PhD, of the National Cancer Institute and her colleagues conducted one of the first studies to assess the link between meat-related compounds and risk of developing bladder cancer. They gathered information through questionnaires that assess the types of meat consumed and how it was prepared and cooked to estimate the intake of meat-related compounds.
The investigators examined information from approximately 300,000 men and women between the ages of 50 and 71 from eight U.S states. During the start of the study (1995 to 1996), all participants completed surveys concerning their usual consumption of foods and drinks. The participants were followed for up to eight years; during that span 854 individuals were diagnosed with bladder cancer.
Investigators found that people whose diets had the highest amount of total dietary nitrite from all food sources, as well as those whose diets accumulated the highest amount of nitrate and nitrite from processed meats had a 28 to 29 percent increased risk of developing bladder cancer. This is in comparison to those who consumed the lowest amount of these compounds. This relationship between nitrate/nitrite consumption and bladder cancer risk may explain why other studies have observed a possible connection between processed meats and bladder cancer risk.
Dr Cross explains, "Our findings highlight the importance of studying meat-related compounds to better understand the association between meat and cancer risk. Comprehensive epidemiologic data on meat-related exposures and bladder cancer are lacking; our findings should be followed up in other prospective studies."