Michaud Dominique S, Fuchs Charles S, Liu Simin, Willett Walter C, Colditz Graham A, Giovannucci Edward
Harvard School of Public Health, Kresge 920, 677 Huntington Avenue, Boston, MA 02115, USA.
Cancer Epidemiol Biomarkers Prev. 2005 Jan;14(1):138-47.
Hyperinsulinemia may explain excess colorectal cancer among individuals who are overweight or inactive. Recent studies have observed elevated colorectal cancer risk among individuals with elevated insulin levels 2 hours after oral glucose challenge or with elevated plasma C-peptide levels. The effect of consuming a high glycemic diet on colorectal risk, however, remains uncertain. Two prospective cohort studies, the Nurses' Health Study and the Health Professionals Follow-up Study, contributed up to 20 years of follow-up. After exclusions, 1,809 incident colorectal cancers were available for analyses. Dietary glycemic load (GL) was calculated as a function of glycemic index (postprandial blood glucose response as compared with a reference food), carbohydrate content, and frequency of intake of individual foods reported on food frequency questionnaires. Multivariable Cox proportional hazards models were used to adjust for potential confounders. Intakes of dietary carbohydrate, GL, overall glycemic index, sucrose, and fructose were not associated with colorectal cancer risk in women. A small increase in risk was observed in men with high dietary GL (multivariate relative risk, 1.32; 95% confidence interval, 0.98-1.79; highest versus lowest quintile), sucrose or fructose (multivariate relative risk, 1.37; 95% confidence interval, 1.05-1.78; highest versus lowest quintile of fructose, P = 0.008). Associations were slightly stronger among men with elevated body mass index (> or =25 kg/m(2)). Results among women were similar after stratifying by body mass index or physical activity. High intakes of GL, fructose, and sucrose were related to an elevated colorectal cancer risk among men. For women, however, these factors did not seem to increase the risk of colorectal cancer.
高胰岛素血症可能解释了超重或缺乏运动的个体中结直肠癌发病率过高的现象。最近的研究发现，口服葡萄糖耐量试验2小时后胰岛素水平升高或血浆C肽水平升高的个体患结直肠癌的风险增加。然而，高血糖饮食对结直肠癌风险的影响仍不确定。两项前瞻性队列研究，即护士健康研究和卫生专业人员随访研究，提供了长达20年的随访数据。排除相关因素后，共有1809例结直肠癌新发病例可供分析。膳食血糖负荷（GL）根据血糖指数（餐后血糖反应与参考食物相比）、碳水化合物含量以及食物频率问卷中报告的个体食物摄入频率来计算。采用多变量Cox比例风险模型对潜在混杂因素进行校正。女性的膳食碳水化合物、GL、总体血糖指数、蔗糖和果糖摄入量与结直肠癌风险无关。膳食GL高的男性（多变量相对风险为1.32；95%置信区间为0.98 - 1.79；最高五分位数与最低五分位数相比）、蔗糖或果糖（多变量相对风险为1.37；95%置信区间为1.05 - 1.78；果糖最高五分位数与最低五分位数相比，P = 0.008）患结直肠癌的风险略有增加。体重指数升高（≥25 kg/m²）的男性中这种关联稍强。按体重指数或身体活动分层后，女性的结果相似。GL、果糖和蔗糖的高摄入量与男性结直肠癌风险升高有关。然而，对于女性来说，这些因素似乎并未增加患结直肠癌的风险。
