Benzoxaxinoids Are Inversely Associated With Prostate-Specific Antigen Levels- a Whole Grain Rye vs Refined Wheat Randomized Cross-Over Trial in Men With Prostate Cancer

Abstract

Abstract Objectives Prostate cancer is a common cancer diagnosis among men, but the role of diet and food components remains controversial. Benzoxazinoids (BXs) is a potent group of bioactive compounds found in rye foods that seem to have the potential to inhibit prostate cancer growth in vitro but studies in humans are lacking. We therefore aimed to investigate the concentrations of different BXs and their metabolites after whole grain rye consumption in comparison to refined wheat and to correlate these compounds to PSA levels in men with indolent prostate cancer. Methods In a randomized controlled crossover study, men with prostate cancer (n = 24) consumed 485 gram of whole grain/bran rye and refined wheat foods for six weeks, with two weeks of washout in-between. The diets were isocaloric and contained the same amount of fiber by addition of cellulose in the refined wheat intervention. BXs in plasma samples were analyzed with HPLC- QTRAP/MS-ESI. Results Seventeen men finished the trial and were included in data analysis. For most BXs, the concentrations were significantly higher after the whole grain rye compared to the refined wheat intervention. The BXs or BXs metabolites HBOA-glc, HHPAA, HBOA-glcA, HPAA-glcA (∼19.4–0.4 nmol/L in plasma after interventions) were significantly inversely correlated to PSA level. Conclusions In men with indolent prostate cancer, most BXs were significantly higher after an intervention with whole grain rye compared to refined wheat. The inverse correlation between four BXs or BXs metabolites and PSA may indicate on an inhibitory effect on prostate cancer cell growth. This could open for new preventive food-based strategies, but results would need to be replicated. Funding Sources Independent Research Fund Denmark - Technology and Production Formas Swedish Research Council.