Dietary supplement use patterns in men with prostate cancer: the Cancer Prostate Sweden Study

Background: In a European setting, we know little about the use of dietary supplements among men with prostate cancer (PCa) and to what extent lifestyle, disease or other factors influence such use. Patients and methods: We evaluated supplement use in 1127 men with incident PCa and in 900 population controls in Sweden. Age-adjusted binary regression with an identity link was carried out to estimate prevalence differences and corresponding 95% confidence intervals (CIs). Modifying effects of lifestyle-and diet-related factors were explored by statistical assessment of additive interaction. Results: Among men with PCa, 542 individuals (48%) had used supplements, which was a 10% (95% CI: 5.9%-15%) higher prevalence than among population controls. Among individuals with high intake of fatty fish, vegetables, and phytoestrogens, but low intake of saturated fat, supplement use was 29% (95% CI: 18%-41%) more common in men with PCa than in population controls. We found no evidence of heterogeneity by categories of education, smoking history, body mass index, fiber, fruit, or phytoestrogen intake, treatment, or disease stage. Conclusion: Supplement use is common in Swedish men with PCa, especially among those with a healthy dietary pattern.