From the Epidemiology and Prevention Group, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan (NS, M Iwasaki, TY, TS, SS, M Inoue, and ST), and AXA Department of Health and Human Security, Graduate School of Medicine, University of Tokyo, Tokyo, Japan (M Inoue).
Am J Clin Nutr. 2015 Jan;101(1):118-25. doi: 10.3945/ajcn.114.089581. Epub 2014 Nov 19.
Dietary fiber may reduce the risk of prostate cancer, possibly by increasing circulating concentrations of sex hormone-binding globulin and improving insulin sensitivity. However, results from previous epidemiologic studies of fiber intake and prostate cancer are inconsistent, and to our knowledge, no study has comprehensively evaluated the effects of soluble and insoluble fiber on prostate cancer in Asia.
The objective was to examine the association between fiber intake and prostate cancer in Japanese men.
We conducted a population-based prospective study in 43,435 Japanese men aged 45-74 y. Participants responded to a validated questionnaire, which included 138 food items. Follow-up was from 1995 through 2009. HRs and 95% CIs of incidence were calculated according to quartiles of fiber intake.
During the 11.6-y follow-up, of the 825 men newly diagnosed with prostate cancer, 213 had advanced-stage cancer, 582 had organ-localized disease, and 30 had an undetermined stage of disease. Among them, 217 cases were detected by subjective symptoms. Total fiber was not associated with total or advanced prostate cancer, with respective multivariable HRs for the highest and lowest quartiles of 1.00 (95% CI: 0.77, 1.29; P-trend = 0.97) and 0.67 (95% CI: 0.42, 1.07; P-trend = 0.30). Total fiber and insoluble fiber intake were associated with a decreased risk of advanced cancers detected by subjective symptoms, with multivariate HRs (95% CIs) across increasing quartiles of 1.00, 0.58, 0.62, and 0.44 (0.21, 0.92; P-trend = 0.05) for total fiber and 1.00, 0.60, 0.52, and 0.46 (0.22, 0.93; P-trend = 0.04) for insoluble fiber. Soluble fiber intake showed no association with prostate cancer.
Dietary fiber is inversely associated with advanced prostate cancer detected by subjective symptoms even among populations with relatively low intake, such as Japanese. These results suggest that a very low intake of dietary fiber is associated with an increased risk of prostate cancer.
膳食纤维可能通过增加循环中性激素结合球蛋白的浓度和改善胰岛素敏感性来降低前列腺癌的风险。然而，之前膳食纤维摄入与前列腺癌的流行病学研究结果并不一致，据我们所知，尚无研究全面评估可溶性和不溶性膳食纤维对亚洲前列腺癌的影响。
本研究旨在探讨日本男性膳食纤维摄入与前列腺癌的关系。
我们对 43435 名年龄在 45-74 岁的日本男性进行了一项基于人群的前瞻性研究。参与者通过一份经过验证的问卷进行了回复，该问卷包含 138 种食物。随访时间从 1995 年持续到 2009 年。根据膳食纤维摄入量的四分位数计算发病率的 HR 和 95%CI。
在 11.6 年的随访期间，新诊断出的 825 名前列腺癌患者中，213 名患者患有晚期癌症，582 名患者患有器官局限性疾病，30 名患者疾病分期不确定。其中，217 例通过主观症状发现。总膳食纤维与总前列腺癌或晚期前列腺癌均无相关性，最高和最低四分位数的多变量 HR 分别为 1.00（95%CI：0.77，1.29；P 趋势=0.97）和 0.67（95%CI：0.42，1.07；P 趋势=0.30）。总膳食纤维和不溶性膳食纤维的摄入量与通过主观症状检测到的晚期癌症风险降低有关，随着四分位数的增加，多变量 HR（95%CI）分别为 1.00、0.58、0.62 和 0.44（0.21，0.92；P 趋势=0.05）对于总膳食纤维和 1.00、0.60、0.52 和 0.46（0.22，0.93；P 趋势=0.04）对于不溶性膳食纤维。可溶性膳食纤维的摄入量与前列腺癌无关。
即使在膳食纤维摄入量相对较低的日本人群中，膳食纤维与通过主观症状检测到的晚期前列腺癌呈负相关。这些结果表明，膳食纤维的极低摄入量与前列腺癌风险的增加有关。
