Introduction

Prostate cancer (PC) is one of the major health concerns among men globally (1). It is presently the second most frequent diagnosed cancer and the sixth leading cause of cancer death for males worldwide (2-5). Among the Iranian males, PC is recognized as the third most prevalent malignancies and the six common cancer in Iranian population (6, 7). Based on the latest systematic review and meta-analysis on the available evidence, the incidence rate of prostate cancer is 7.1 per 100 000 in Iranian population. However, it has also been showed that the rate of disease incidence increased from 1996 to 2012 that should be noticed regarding the epidemiological and clinical practices (8). Well-known risk factors for prostate cancer are age, ethnicity, and family history of the disease (9). However, some other risk factors such as diet, alcohol consumption, exposure to ultraviolet radiation, chronic inflammation, and occupational exposure might be involved in the pathogenesis of the disease(10).
The association between dietary patterns and the risk of PC has been investigated in several studies, which has led to inconsistent results. Some studies showed that adherence to a Western dietary pattern could increase the risk of prostate cancer (11-15), but others did not find any associations (16-18). In addition, some studies showed inconsistent findings about the association between healthy eating index and Mediterranean dietary pattern and the risk of PC (11, 13, 14, 16-23). Recently, the importance of dietary acid load is highlighted as the evidence shows that dietary intake is a key factor in the regulation of body’s acid-base status (24, 25) and the kidneys are the main route of excretion of the acid load to maintain acid-base balance (26). Basically, it seems that western diets (with higher meat consumption), and healthy diets (with higher fruits and vegetables consumption and lower meat and processed grain intake) are associated with the acidic and alkali status of the diets, respectively (25, 27). In order to estimate dietary acid load, the potential renal acid load (PRAL) and the net endogenous acid production (NEAP), calculate from dietary intake (24, 28). The association between dietary acid load and several cardiovascular risk factors has been investigated previously (29-33). However, few studies investigated the association between diet-dependent acid load with cancer (34, 35). Therefore, we aimed to investigate the association between diet-dependent acid load and risk of PC in Iranian population.