Glycemic load, glycemic index, and pancreatic cancer risk in the Netherlands Cohort Study

BACKGROUND: Recent studies of pancreatic cancer suggest a role for hyperinsulinemia in carcinogenesis. Because insulin is secreted in response to elevated blood glucose concentrations, dietary factors that increase these concentrations may be important in pancreatic carcinogenesis. OBJECTIVE: The objective was to examine prospectively the relation between pancreatic cancer risk and dietary glycemic load (GL), overall glycemic index (GI), and intake of total carbohydrates and mono- and disaccharides. DESIGN: The Netherlands Cohort Study consisted of 120,852 men and women who completed a baseline questionnaire in 1986. After 13.3 y of follow-up, 408 pancreatic cancer cases were detected, 66% of which were microscopically confirmed. A validated 150-item food-frequency questionnaire, completed at baseline, was used to calculate carbohydrate and mono- and disaccharide intakes and the GL and GI of the diet. RESULTS: Dietary GL, GI, or intake of carbohydrates and mono- and disaccharides were not associated with pancreatic cancer risk in this cohort. Also, the associations were not modified by sex. Our results did not change after the analysis was restricted to microscopically confirmed pancreatic cancer cases or after individuals who reported a history of diabetes at baseline were excluded from the analyses. CONCLUSIONS: Overall, our findings do not support the hypothesis that GL, GI, or intake of carbohydrates and mono- and disaccharides are positively associated with pancreatic cancer risk. This is in agreement with previous prospective studies that investigated the relation between GL and GI and pancreatic cancer risk.     

The association of glycemic load and carbohydrate intake with colorectal cancer risk in the Multiethnic Cohort Study

BACKGROUND: High-glycemic-load diets may increase colorectal cancer risk through hyperinsulinemic effects. OBJECTIVE: We analyzed data for 191,004 participants in the Multiethnic Cohort Study to determine the risk of colorectal cancer associated with glycemic load (GL), carbohydrate, and sucrose and to ascertain whether this risk was modified by sex and ethnicity. DESIGN: During 8 y of follow-up, 2379 incident cases of colorectal adenocarcinoma occurred. We used baseline quantitative food-frequency questionnaire data to assess usual dietary intake over the preceding year. Using Cox regression, we calculated adjusted relative risks (RRs) and 95% CIs for colorectal cancer associated with quintiles of GL, carbohydrate, and sucrose. RESULTS: For both men and women in this cohort, white rice was the major contributor to GL. In multivariate models, RRs for colorectal cancer decreased significantly with increasing GL in women (RR for the highest quintile versus the lowest: 0.75; 95% CI: 0.57, 0.97; P for trend = 0.02) but not in men (RR: 1.15; 95% CI: 0.89, 1.48; P for trend = 0.19). Results for carbohydrate and sucrose were similar. The inverse association with GL was found in women of all ethnic groups (P for interaction = 0.58). In men, an interaction was found between ethnicity and GL (P < 0.01): white men had a positive association with increasing GL (RR: 1.69; 95% CI: 0.98, 2.92; P for trend < 0.01), but men of other ethnic groups did not. CONCLUSION: GL and carbohydrate intake appear to protect against colorectal cancer in women in the Multiethnic Cohort, perhaps because a major source of GL is white rice.     

Dietary carbohydrates, glycemic index, glycemic load, and endometrial cancer risk within the European Prospective Investigation into Cancer and Nutrition cohort

The associations of dietary total carbohydrates, overall glycemic index, total dietary glycemic load, total sugars, total starch, and total fiber with endometrial cancer risk were analyzed among 288,428 women in the European Prospective Investigation into Cancer and Nutrition cohort (1992-2004), including 710 incident cases diagnosed during a mean 6.4 years of follow-up. Cox proportional hazards models were used to estimate relative risks and 95% confidence intervals. There were no statistically significant associations with endometrial cancer risk for increasing quartile intakes of any of the exposure variables. However, in continuous models calibrated by using 24-hour recall values, the multivariable relative risks were 1.61 (95% confidence interval: 1.06, 2.45) per 100 g/day of total carbohydrates, 1.40 (95% confidence interval: 0.99, 1.99) per 50 units/day of total dietary glycemic load, and 1.36 (95% confidence interval: 1.05, 1.76) per 50 g/day of total sugars. These associations were stronger among women who had never used postmenopausal hormone therapy compared with ever users (total carbohydrates p(heterogeneity) = 0.04). Data suggest no association of overall glycemic index, total starch, and total fiber with risk, and a possible modest positive association of total carbohydrates, total dietary glycemic load, and total sugars with risk, particularly among never users of hormone replacement therapy.     

Dietary glycemic load, glycemic index, and carbohydrate and risk of breast cancer in the Women's Health Initiative

Dietary glycemic load (GL), glycemic index (GI), and carbohydrate could be associated with breast cancer risk by influencing long-term blood glucose and insulin concentrations. We examined associations between GL, GI, and carbohydrate and incident breast cancer in 148,767 Women's Heath Initiative (WHI) participants. Dietary variables were estimated from food frequency questionnaires administered at baseline. Self-reported breast cancers during follow-up were confirmed by medical records review. Cox proportional hazards regression modeled time to breast cancer within quintiles of GL, GI, and carbohydrate. There were 6,115 total breast cancers after a median follow-up of 8.0 yr. We observed no associations between GL, GI, or carbohydrate and total incident breast cancer, with hazard ratios and 95% confidence intervals for the highest vs. lowest quintiles of 1.08, 0.92-1.29 (P for trend = 0.27); 1.01, 0.91-1.12 (P = 0.74); and 0.95, 0.80-1.14 (P = 0.98), respectively. There was a trend toward significance for the positive association between GL and in situ cancers (1.40, 0.94-2.13; P = 0.07). Although there was no evidence of associations between GL, GI, or carbohydrate and total breast cancer risk in WHI participants, the suggestion of an association between GL and risk of in situ cancers requires further investigation.     

Dietary glycemic index, glycemic load, and the risk of breast cancer in an Italian prospective cohort study

BACKGROUND: Interest in the roles of glycemic index (GI) and glycemic load (GL) in breast cancer etiology has been stimulated by indications that disease risk is linked to insulinemia, sex hormone bioavailability, and insulin-like growth factor 1. OBJECTIVE: We aimed to determine whether GI and GL were associated with the risk of breast cancer in a cohort of Italian women volunteers from Northern Italy, who enrolled between 1987-1992 in the Hormones and Diet in the Etiology of Breast Tumors Study (ORDET Study). DESIGN: Volunteers completed a semiquantitative food-frequency questionnaire, and anthropometric and lifestyle data were collected. Dietary GI and GL in relation to breast cancer risk were examined in 8926 cohort women, including 289 with breast cancer identified after a mean follow-up of 11.5 y. RESULTS: The relative risk (RR) of breast cancer in the highest (versus lowest) quintiles of GI and GL was 1.57 (95% CI: 1.04, 2.36; P for trend = 0.040) and 2.53 (95% CI: 1.54, 4.16; P for trend = 0.001), respectively. Total carbohydrate intake was not associated with greater breast cancer risk, but high carbohydrate from high-GI foods was. When women were categorized by baseline menopausal status and body mass index (BMI; in kg/m(2)), the increased risk of dietary GL was confined to those who were premenopausal (RR = 3.89; 95% CI: 1.81, 8.34) and who had normal BMI (ie, <25) (RR = 5.79; 95% CI: 2.60, 12.90) (P for trend = 0.001 for both). CONCLUSIONS: A high-GL diet may increase the risk of breast cancer in Italian women. The effect is particularly evident in premenopausal women and those with BMI < 25.     

Dietary carbohydrate, glycemic index, and glycemic load in relation to risk of colorectal cancer in women

Diets with a high glycemic index and glycemic load have been hypothesized to be implicated in the etiology of colorectal cancer owing to their potential to increase postprandial glucose and insulin levels. Prospective data on glycemic index and glycemic load in relation to colorectal cancer risk are limited and inconsistent. Therefore, the authors prospectively investigated the associations of dietary carbohydrate, glycemic index, and glycemic load with the incidence of colorectal cancer among 61,433 Swedish women who were free of cancer in 1987-1990 and completed a 67-item food frequency questionnaire. During follow-up through June 2005, 870 incident cases of colorectal adenocarcinoma were diagnosed. Carbohydrate intake, glycemic index, and glycemic load were not associated with risk of colorectal cancer, colon cancer, or rectal cancer. The multivariate hazard ratios for colorectal cancer comparing the highest with the lowest quintile were 1.10 (95% confidence interval: 0.85, 1.44) for carbohydrate intake, 1.00 (95% confidence interval: 0.75, 1.33) for glycemic index, and 1.06 (95% confidence interval: 0.81, 1.39) for glycemic load. Results did not vary by body mass index. The findings from this prospective study do not support the hypothesis that a high carbohydrate intake, a high glycemic index, and a high glycemic load increase the risk of colorectal cancer.     

Dietary glycemic load and risk of age-related cataract

BACKGROUND: Metabolism of many of the most commonly consumed carbohydrates in the United States results in a high plasma glucose response, which can be quantified by the glycemic load. Although hyperglycemia is a risk factor for cataract, there is no information on the potential effect of a high dietary glycemic load on the incidence of age-related cataract. OBJECTIVE: Our objective was to prospectively examine the association between dietary glycemic load and incident age-related cataract. DESIGN: We studied 2 cohorts-71 919 women and 39 926 men-aged > or =45 y who had no previous diagnosis of cataract, diabetes mellitus, or cancer and who were followed for 14 and 12 y, respectively, for the occurrence of cataract extraction. We calculated dietary glycemic load from data reported on multiple validated food-frequency questionnaires and used pooled logistic regression models to estimate the association with incident cataract extraction. We performed analyses separately for each cohort and then calculated pooled estimates across cohorts. RESULTS: During 980 683 person-years of follow-up, we confirmed 4865 incident age-related cataract extractions. After adjustment for age, cigarette smoking, body mass index, total caloric intake, dietary intake of lutein and zeaxanthin, and alcohol consumption, there was no significant relation of dietary glycemic load to risk of cataract extraction (P for trend = 0.10). The pooled relative risk between the highest and lowest quintiles of dietary glycemic load was 0.95 (95% CI: 0.81, 1.11; P for heterogeneity by cohort = 0.1). CONCLUSION: These prospective epidemiologic data do not support the hypothesis that a high dietary glycemic load, primarily a result of consumption of refined carbohydrates, increases the risk of cataract extraction.     

Calcium, vitamin D, and dairy product intake and prostate cancer risk: the Multiethnic Cohort Study

High intakes of calcium and dairy products have been suggested to be related to prostate cancer risk. Such associations were examined in the Multiethnic Cohort Study (1993-2002) among 82,483 men who completed a detailed quantitative food frequency questionnaire. During a mean follow-up of 8 years, 4,404 total cases of prostate cancer were identified. In Cox proportional hazards models, no association was found between calcium and vitamin D intake and total, advanced, or high-grade prostate cancer risk, whether for total intake, intake from foods, or intake from supplements, among all male participants or among nonusers of supplemental calcium. No association of calcium or vitamin D intake was seen across racial/ethnic groups. In analyses of food groups, dairy product and total milk consumption were not associated with prostate cancer risk. However, low-/nonfat milk was related to an increased risk and whole milk to a decreased risk of total prostate cancer; after stratification, these effects were limited to localized or low-grade tumors. Although the findings from this study do not support an association between the intakes of calcium and vitamin D and prostate cancer risk, they do suggest that an association with milk consumption may vary by fat content, particularly for early forms of this cancer.     

Calcium and vitamin D intake and risk of colorectal cancer: the Multiethnic Cohort Study

The associations of intakes of calcium and vitamin D with colorectal cancer risk were examined in the Multiethnic Cohort Study (Hawaii and Los Angeles, California). In 1993-1996, 85,903 men and 105,108 women aged > or =45 years completed a quantitative food frequency questionnaire. A total of 2,110 incident cases of colorectal cancer (1,138 in men and 972 in women) were identified through December 31, 2001. Cox proportional hazards models were used to calculate multivariate-adjusted relative risks and 95% confidence intervals. Total calcium intake (from foods and supplements) was inversely associated with colorectal cancer risk in both men (highest quintile vs. lowest: relative risk (RR) = 0.70, 95% confidence interval (CI): 0.52, 0.93; p for trend = 0.006) and women (RR = 0.64, 95% CI: 0.50, 0.83; p for trend = 0.003). The inverse association was also seen for total vitamin D intake in men (RR = 0.72, 95% CI: 0.51, 1.00; p for trend = 0.03) but not in women. Intake of dairy products was inversely associated with colorectal cancer risk, especially among nonusers of supplemental calcium (men: RR = 0.77, 95% CI: 0.59, 1.01; women: RR = 0.66, 95% CI: 0.49, 0.89). The findings support the hypothesis of protective roles for calcium, vitamin D, and dairy products in the risk of colorectal cancer.     

Dietary carbohydrates, fiber, and breast cancer risk

Dietary fiber, fiber fractions, carbohydrate, glycemic index, and glycemic load were prospectively assessed five times over 18 years with a validated food frequency questionnaire in relation to breast cancer risk among 88,678 women (aged 34-59 years at baseline) in the Nurses' Health Study. Incident breast cancer occurred in 4,092 of these women between 1980 and 1998. The authors observed no material association between carbohydrate intake, glycemic index and glycemic load, total dietary fiber intake, and breast cancer risk. The relative risks for the highest versus the lowest quintile of intake were 0.97 (95% confidence interval (CI): 0.87, 1.08) for carbohydrates, 1.08 (95% CI: 0.97, 1.19) for glycemic index, 0.99 (95% CI: 0.89, 1.10) for glycemic load, and 0.98 (95% CI: 0.87, 1.11) for fiber. The relative risk comparing those in the highest 0.7% of fiber intake (>30 g/day) with those in the lowest 10% of fiber intake (< or =10 g/day) was 0.68 (95% CI: 0.43, 1.06). Analyses stratified by menopausal status and body mass index also showed no clear risk pattern. In this cohort of middle-aged women, no overall association was found for dietary carbohydrates, glycemic index and glycemic load, and breast cancer risk. This study also confirmed the lack of an overall association between intake of fiber and fiber types and breast cancer risk observed in other prospective studies.     

Glycemic index, glycemic load, and cancer risk: a meta-analysis

BACKGROUND: Factors linked to glucose metabolism play an important role in the development of cancers, and both glycemic index (GI) and glycemic load (GL) have been investigated as potential etiologic factors. OBJECTIVE: A meta-analysis was performed to explore the association between GI and GL and cancer risk from published studies. DESIGN: A comprehensive, systematic bibliographic search of the medical literature was conducted to identify relevant studies. Case-control and cohort studies published before October 2007 that reported cancer risk estimates for GI and GL were included. Pooled relative risks (RRs) were estimated for breast, colorectal, endometrial, and pancreatic cancer. RESULTS: Thirty-nine studies were included in the meta-analysis. The interquantile ranges of GL were significantly wider in case-control studies, most of which were conducted in European countries, than in cohort studies. Cohort studies that presented lower ranges of GL also reported lower risk estimates. Overall, both GL and GI were significantly associated with a greater risk of colorectal (summary RR = 1.26; 95% CI: 1.11, 1.44 and RR = 1.18; 95% CI: 1.05, 1.34, respectively) and endometrial (RR = 1.36; 95% CI: 1.14, 1.62 and RR = 1.22; 95% CI: 1.01, 1.49) cancer than of breast and pancreatic cancer. There was, however, a significant between-study heterogeneity for colorectal cancer (P < 0.0001). The association between GL and breast cancer disappeared when publication bias was taken into account. No association was found for pancreatic cancer. CONCLUSION: This comprehensive meta-analysis of GI and GL and cancer risk suggested an overall direct association with colorectal and endometrial cancer.     

Dietary glycemic index and glycemic load and the risk of type 2 diabetes in older adults

BACKGROUND: It is unclear whether immediate dietary effects on blood glucose influence the risk of developing type 2 diabetes. OBJECTIVE: The objective of this study was to examine whether the dietary glycemic index (GI) and glycemic load (GL) were associated with the risk of type 2 diabetes in older adults. DESIGN: The Health, Aging, and Body Composition Study is a prospective cohort study of 3075 adults who were 70-79 y old at baseline (n=1898 for this analysis). The intakes of specific nutrients and food groups and the risk of type 2 diabetes over a 4-y period were examined according to dietary GI and GL. RESULTS: Dietary GI was positively associated with dietary carbohydrate and negatively associated with the intakes of protein, total fat, saturated fat, alcohol, vegetables, and fruit. Dietary GL was positively associated with dietary carbohydrate, fruit, and fiber and negatively associated with the intakes of protein, total fat, saturated fat, and alcohol. Persons in the higher quintiles of dietary GI or GL did not have a significantly greater incidence of type 2 diabetes. CONCLUSIONS: These findings do not support a relation between dietary GI or GL and the risk of type 2 diabetes in older adults. Because dietary GI and GL show strong nutritional correlates, the overall dietary pattern should be considered.     

Dietary glycemic index and load in relation to cardiovascular disease risk factors in Cuban American population

Objective To examine whether dietary glycemic index (GI) or glycemic load (GL) had an effect on the cardiovascular disease (CVD) risk factors and whether the effects were dependent on the diabetes status in the Cuban American population.

Design A case–control, single-time-point study.

Methods A total of 324 middle-aged Cuban American adults had completed data on fasting blood lipids, physical activity level and usual dietary intake using a validated food frequency questionnaire. Published GI values were assigned to food items and average dietary GI and GL were calculated per participant.

Results Subjects without type 2 diabetes (T2D) were 3.3 times more likely to be in the recommended, highest high-density lipoprotein-cholesterol category if they were in the second dietary GL tertile as compared with those in the first dietary GL tertile (P = 0.042, 95% confidence interval = 1.94, 10.78).

Conclusions The results of the present study suggest that in this sample of Cuban Americans a high GI or GL diet do not adversely affects blood lipids, especially among subjects without T2D.