The association of diet-dependent acid load with colorectal cancer risk: a case-control study in Korea.

Acid‒base disequilibrium is a contributor to cancer development because it affects molecular activities such as insulin-like growth factor 1 levels and adiponectin production. However, evidence of an association of diet-induced acid‒base imbalance with colorectal cancer (CRC) is limited. We examined whether colorectal carcinogenesis is attributable to a diet with a high acid load. We recruited a total of 923 CRC cases and 1846 controls at the National Cancer Center in Korea for inclusion in a case-control study. We collected information on nutrient intake and specific clinical parameters of CRC by using a semiquantitative food frequency questionnaire and medical records, respectively. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) were used to estimate diet-dependent acid load. We used an unconditional logistic regression model to analyse the association. Dietary acid load scores had a positive association with the odds of CRC risk (odds ratio (OR)= 2.31 (95% confidence interval (CI): 1.79-2.99) and OR=2.14 (95% CI: 1.66-2.76) for PRAL and NEAP, respectively, P for trends<0.001). A stronger positive association was observed for females (OR=3.09, 95% CI: 1.93-4.94) than for males (OR=1.71, 95% CI: 1.27-2.31). Furthermore, acidogenic diets appeared to affect rectal cancer more strongly than colon cancer in females. Our study contributes to reinforcing epidemiological evidence regarding a detrimental effect of acidogenic diets on colorectal carcinogenesis. Thus, it is important to pay attention to the balance of acidogenic (e.g., poultry and red meat) and alkalinogenic foods (e.g., fruits and vegetables) in CRC prevention, especially for females.