Galeone et al. (2007) Onion and garlic intake and the odds of benign prostatic hyperplasia. Urology 70: 672–676

The role of diet in the development of benign prostatic hyperplasia (BPH) has not been extensively researched, although evidence suggests that BPH incidence is inversely associated with fruit and vegetable intake. In addition, vegetables from the Allium genus have shown beneficial effects in various disorders affecting the prostate. Galeone and colleagues performed a multicenter, case–control study to evaluate the risk of BPH associated with onion and garlic intake during the 2 years before diagnosis or hospital admission.

The study included 1,369 patients with clinically detected BPH (median age 66 years, disease diagnosis <1 year before enrolment) admitted to major teaching and general hospitals in four regions of Italy. The control group consisted of 1,451 individuals (median age 63 years) in the same hospitals, who were admitted with non-neoplastic illnesses unrelated to diet modification. All participants completed a detailed questionnaire, which included sections about sociodemographic factors, medical history and family history of cancer. Onion consumption was categorized as none, infrequent (<4 80 g portions/week) or regular (≥4 80 g portions/week); garlic consumption was represented by a qualitative score (1 = none or low frequency, 2 = intermediate frequency, 3 = high frequency).

On multivariate analysis, the odds ratios for BPH in the highest-consuming categories for onion and garlic intake were 0.41 (95% CI 0.24–0.72) and 0.72 (95% CI 0.57–0.91), respectively. Frequent consumption of both onions and garlic yielded an odds ratio of 0.65 (95% CI 0.49–0.86).

The authors conclude that increased intake of Allium vegetables seems to be associated with a decreased risk of developing BPH.