Karagas M R, Tosteson T D, Greenberg E R, Rothstein R I, Roebuck B D, Herrin M, Ahnen D
Department of Community and Family Medicine, and the Norris Cotton Cancer Center, Hanover, New Hampshire 03756, USA.
Cancer Epidemiol Biomarkers Prev. 1998 Sep;7(9):757-66.
Intake of dairy products and major dairy constituents (e.g., calcium) has been proposed to reduce the risk of colorectal cancer, although epidemiological studies have yielded inconclusive results. We conducted a randomized cross-over trial to test the effects of high- and low-dairy consumption diets on rectal mucosal proliferation, a possible intermediary marker for large bowel cancer. From a gastroenterology clinic at an academic medical center, we recruited 40 patients, ages 25-79 years, who had either a history of a large bowel adenoma or a first-degree relative with large bowel cancer. Participants completed a baseline questionnaire covering demographic characteristics, health history, and habits and a food frequency questionnaire. They were randomized to a 12-week diet of either high dairy intake (six dairy servings/day) or low dairy intake (<0.5 serving of dairy products/day), with an intervening 12-week washout period in which they were asked to resume their usual diet before crossing over to the alternate study diet for the last 12-week period of the study. Adherence to the study diets was monitored by a daily dairy intake checklist and periodic, unscheduled 24-h dietary recalls. Biopsies of the rectal mucosa were obtained at the beginning and end of each intervention phase. Two assays of rectal mucosal cell proliferation were performed: immunohistochemical determination of proliferating cell nuclear antigen and whole crypt mitotic count. We found no statistically significant changes in either of these proliferation measures as a result of high or low dairy intake. There was no correlation between the labeling index for proliferating cell nuclear antigen and whole crypt mitotic count; however, measures of the location and intensity of cell proliferation within the rectal crypt were highly correlated between the two assays. Thus, our study indicates that greater consumption of dairy products over a 12-week period does not change rectal mucosal cell proliferation.
尽管流行病学研究结果尚无定论，但有人提出摄入乳制品及主要乳制品成分（如钙）可降低患结直肠癌的风险。我们进行了一项随机交叉试验，以测试高乳制品摄入量饮食和低乳制品摄入量饮食对直肠黏膜增殖的影响，直肠黏膜增殖是大肠癌可能的中间标志物。我们从一所学术医疗中心的胃肠病诊所招募了40名年龄在25 - 79岁之间的患者，这些患者要么有大肠腺瘤病史，要么有患大肠癌的一级亲属。参与者完成了一份涵盖人口统计学特征、健康史和生活习惯的基线问卷以及一份食物频率问卷。他们被随机分配到为期12周的高乳制品摄入量饮食组（每天六份乳制品）或低乳制品摄入量饮食组（每天少于0.5份乳制品），中间有一个为期12周的洗脱期，在此期间要求他们恢复正常饮食，然后在研究的最后12周期间转换到另一种研究饮食。通过每日乳制品摄入量清单以及定期、不定期的24小时饮食回顾来监测对研究饮食的依从性。在每个干预阶段开始和结束时获取直肠黏膜活检样本。进行了两项直肠黏膜细胞增殖检测：增殖细胞核抗原的免疫组化测定和全隐窝有丝分裂计数。我们发现，高乳制品摄入量或低乳制品摄入量对这两种增殖指标均无统计学上的显著变化。增殖细胞核抗原的标记指数与全隐窝有丝分裂计数之间无相关性；然而，两种检测方法中直肠隐窝内细胞增殖的位置和强度测量结果高度相关。因此，我们的研究表明，在12周内增加乳制品摄入量不会改变直肠黏膜细胞增殖。
