Carbohydrate intake, glycemic index, glycemic load, and risk of postmenopausal breast cancer in a prospective study of French women

BACKGROUND: Diets high in carbohydrates may result in chronically elevated insulin concentrations and may affect breast cancer risk by stimulation of insulin receptors or through insulin-like growth factor I (IGF-I)-mediated mitogenesis. Insulin response to carbohydrate intake is increased in insulin-resistant states such as obesity. OBJECTIVE: We sought to evaluate carbohydrate intake, glycemic index (GI), and glycemic load (GL) and subsequent overall and hormone-receptor-defined breast cancer risk among postmenopausal women. DESIGN: A prospective cohort analysis of dietary carbohydrate and fiber intakes was conducted among 62 739 postmenopausal women from the E3N French study who had completed a validated dietary history questionnaire in 1993. During a 9-y period, 1812 cases of pathology-confirmed breast cancer were documented through follow-up questionnaires. Nutrients were categorized into quartiles and energy-adjusted with the regression-residual method. Cox model-derived relative risks (RRs) were adjusted for known determinants in breast cancer. RESULTS: Dietary carbohydrate and fiber intakes were not associated with overall breast cancer risk. Among overweight women, we observed an association between GI and breast cancer (RR(Q1-Q4): 1.35; 95% CI: 1.00, 1.82; P for trend = 0.04). For women in the highest category of waist circumference, the RR(Q1-Q4) was 1.28 (95% CI: 0.98, 1.67; P for trend = 0.10) for carbohydrates, 1.35 (95% CI: 1.04, 1.75; P for trend = 0.01) for GI, and 1.37 (95% CI: 1.05, 1.77; P for trend = 0.003) for GL. We also observed a direct association between carbohydrate intake, GL, and estrogen receptor-negative breast cancer risk. CONCLUSIONS: Rapidly absorbed carbohydrates are associated with postmenopausal breast cancer risk among overweight women and women with large waist circumference. Carbohydrate intake may also be associated with estrogen receptor-negative breast cancer.     

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 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.     

Glycemic index, glycemic load, and chronic disease risk--a meta-analysis of observational studies

BACKGROUND: Inconsistent findings from observational studies have prolonged the controversy over the effects of dietary glycemic index (GI) and glycemic load (GL) on the risk of certain chronic diseases. OBJECTIVE: The objective was to evaluate the association between GI, GL, and chronic disease risk with the use of meta-analysis techniques. DESIGN: A systematic review of published reports identified a total of 37 prospective cohort studies of GI and GL and chronic disease risk. Studies were stratified further according to the validity of the tools used to assess dietary intake. Rate ratios (RRs) were estimated in a Cox proportional hazards model and combined by using a random-effects model. RESULTS: From 4 to 20 y of follow-up across studies, a total of 40 129 incident cases were identified. For the comparison between the highest and lowest quantiles of GI and GL, significant positive associations were found in fully adjusted models of validated studies for type 2 diabetes (GI RR = 1.40, 95% CI: 1.23, 1.59; GL RR = 1.27, 95% CI: 1.12, 1.45), coronary heart disease (GI RR = 1.25, 95% CI: 1.00, 1.56), gallbladder disease (GI RR = 1.26, 95% CI: 1.13, 1.40; GL RR = 1.41, 95% CI: 1.25, 1.60), breast cancer (GI RR = 1.08, 95% CI: 1.02, 1.16), and all diseases combined (GI RR = 1.14, 95% CI: 1.09, 1.19; GL RR = 1.09, 95% CI: 1.04, 1.15). CONCLUSIONS: Low-GI and/or low-GL diets are independently associated with a reduced risk of certain chronic diseases. In diabetes and heart disease, the protection is comparable with that seen for whole grain and high fiber intakes. The findings support the hypothesis that higher postprandial glycemia is a universal mechanism for disease progression.     

Dietary patterns related to glycemic index and load and risk of premenopausal and postmenopausal breast cancer in the Western New York Exposure and Breast Cancer Study

BACKGROUND: Reduced rank regression (RRR) has been used to identify dietary patterns that predict variation in a selected risk factor and may be useful in describing dietary exposures associated with glycemic index (GI) and glycemic load (GL). OBJECTIVE: To estimate breast cancer risk, we compared the relative utility of RRR-derived dietary patterns predictive of GI and GL with those of simple GI and GL. DESIGN: RRR was used to identify dietary patterns predicting GI and GL from food-frequency data obtained in the Western New York Exposure and Breast Cancer Study (1166 cases, 2105 controls). Odds ratios (ORs) and 95% CIs were estimated with unconditional logistic regression, adjusted for energy and nondietary breast cancer risk factors. RESULTS: Sweets, refined grains, and salty snacks explained 34% of the variance in GI and 68% of the variance in GL. In general, breast cancer risks were not associated with GI, GL, or dietary pattern score. However, we observed a significant reduction in postmenopausal breast cancer risk with GI and GL pattern scores combined (OR: 0.68; 95% CI: 0.50, 0.93), especially in women with a body mass index (in kg/m(2)) >or=25 (OR: 0.64; 95% CI: 0.44, 0.93). Conversely, in premenopausal women, increased risks were associated with high GL pattern scores only for women with a body mass index >or=25 (OR: 2.21; 95% CI: 1.04, 4.69). CONCLUSIONS: Although RRR may be useful in studies of diet and disease, our results suggest that RRR dietary patterns based on GI and GL provide similar information regarding the association between breast cancer, GI, and GL.     

Associations of Dietary Glycemic Index,Glycemic Load and Carbohydrate with the Risk of Cervical Intraepithelial Neoplasia and Cervical Cancer: A Case-Control Study

Background: The association of dietary glycemic index (GI) and glycemic load (GL) with the risk of cervical cancer has never been investigated. Thus, we aimed to find evidence of any association of GI and GL with the risk of cervical intraepithelial neoplasia (CIN) and cervical cancer. Methods: In this hospital-based case-control study, we included 1340 women (670 controls and 262, 187 and 221 patients with CIN1, CIN2/3, and cervical cancer, respectively) from the Korean human papillomavirus cohort study. Completed demographic questionnaires and semi-quantitative food-frequency questionnaires were collected. The association of dietary GI and GL with CIN and cervical cancer was estimated using a logistic regression model. Results: The multivariate odds ratios (OR) of the highest compared with the lowest quintile of GL for CIN1 were 2.8 (95% confidence interval (CI) = 1.33–5.88). Dietary GI and GL were not associated with CIN2/3 and cervical cancer. Stratified analyses by body mass index (BMI) indicated a positive association between GI and GL and CIN 1 risk among women with a BMI (in kg/m²) <23 (OR = 2.94; 95% CI = 1.32–6.53; p for trend = 0.031 for GI and OR = 3.15; 95% CI = 1.53–6.52; p for trend = 0.013 for GL), but not among those with a BMI of ≥23. A stratification analysis by menopausal status showed that the highest quintile of GI and GL was significantly associated with the risk of CIN1 (OR = 2.91; 95% CI = 1.43–5.96; p for trend = 0.005) (OR = 2.96; 95% CI = 1.53–5.69; p for trend = 0.023) among premenopausal women. Also, in HPV positive women, dietary GL showed significant CIN1 risk (OR = 2.61; 95% CI = 1.09–6.24; p for trend = 0.087). Conclusion: Our case-control study supports the hypothesized associations of dietary GI and GL with increased risk of CIN1. Thus, the consumption of low GI and GL foods plays a significant role in the prevention of cervical carcinogenesis.     

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.     

Cross-sectional relationship between dietary carbohydrate, glycaemic index, glycaemic load and risk of the metabolic syndrome in a Korean population

Little is known about the effect of dietary carbohydrate, glycaemic index (GI) and glycaemic load (GL) on the risk of the metabolic syndrome, especially in populations with white rice as the staple food. The study examined the cross-sectional relationship between carbohydrate, GI, GL and risk of the metabolic syndrome. There were a total of 910 middle-aged Korean adults. Dietary carbohydrate, GI and GL were determined by an interview-administered FFQ. The metabolic syndrome was defined using the modified criteria published in the Third Report of the National Cholesterol Education Program Adult Treatment Panel III. The risk of developing the metabolic syndrome was positively related to dietary carbohydrate (P for trend = 0.03), GI (P for trend = 0.03) and GL intakes (P for trend = 0.02) in women after adjusting for potential confounding variables. Among the components of developing the metabolic syndrome, the risk of high TAG and low HDL-cholesterol were positively related to high GI and GL intakes in women. The risk of developing the metabolic syndrome was considerably higher in the highest quintiles of carbohydrate (OR 6.44; 95 % CI 2.16, 19.2), GI (OR 10.4; 95 % CI 3.24, 33.3) and GL intakes (OR 6.68; 95 % CI 2.30, 19.4) than in the lowest quintiles among women with a BMI >/= 25 kg/m2. However, there was no difference in risk across quintiles of carbohydrate, GI and GL among women with a BMI < 25 kg/m2. In conclusion, both the quantity and quality of carbohydrate intake has a positive relationship with the risk of the metabolic syndrome in women but this relationship was dependent on the BMI level.     

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 and glycemic load are associated with high-density-lipoprotein cholesterol at baseline but not with increased risk of diabetes in the Whitehall II study

BACKGROUND: Findings of the effect of dietary glycemic index (GI) and glycemic load (GL) on the risk of incident diabetes are inconsistent. OBJECTIVE: We examined the associations of dietary GI and GL with clinical variables at baseline and the incidence of diabetes. DESIGN: The 7321 white Whitehall II participants (71% men) attending screening in 1991-1993, free of diabetes at baseline, and with food-frequency questionnaire data were followed for 13 y. RESULTS: At baseline, dietary GI and GL were associated inversely with HDL cholesterol, and GI was associated directly with triacylglycerols. Dietary GI and GL were related inversely to fasting glucose and directly to 2-h postload glucose, but only the association between GI and 2-h postload glucose was robust to statistical adjustments for employment grade, physical activity, smoking status, and intakes of alcohol, fiber, and carbohydrates. High-dietary GI was not associated with increased risk of incident diabetes. Hazard ratios (HRs) across sex-specific tertiles of dietary GI were 1.00, 0.95 (95% CI: 0.73, 1.24), and 0.94 (95% CI: 0.72, 1.22) (adjusted for sex, age, and energy misreporting; P for trend = 0.64). Corresponding HRs across tertiles of dietary GL were 1.00, 0.92 (95% CI: 0.71, 1.19), and 0.70 (95% CI: 0.54, 0.92) (P for trend = 0.01). The protective effect on diabetes risk remained significant after adjustment for employment grade, smoking, and alcohol intake but not after further adjustment for carbohydrate and fiber intakes. CONCLUSION: The proposed protective effect of low-dietary GI and GL diets on diabetes risk could not be confirmed in this study.     

Reproducibility and validity of dietary glycemic index, dietary glycemic load, and total carbohydrate intake in 141 Swedish men

BACKGROUND: Although the associations of dietary glycemic index (GI) and dietary glycemic load (GL) with many chronic diseases have been examined in epidemiologic studies, information regarding the reproducibility and validity of these measures assessed with the use of food-frequency questionnaires (FFQs) is lacking. OBJECTIVE: We examined the reproducibility and validity of dietary GI and dietary GL and of carbohydrate intake as assessed by using an FFQ. DESIGN: Swedish men (n = 141) aged 40-74 y completed 2 FFQs 1 y apart and two 1-wk weighed diet records 6 mo apart. Dietary GI, dietary GL, and carbohydrate intake (starches and sugars) were calculated from both FFQs and diet records. We used intraclass correlations between the 2 FFQs to measure reproducibility and Pearson correlations between the diet records and the FFQs to assess the relative validity. RESULTS: Reproducibility of the FFQs was 0.66 (95% CI: 0.56, 0.75) for dietary GI, 0.61 (95% CI: 0.50, 0.71) for dietary GL, and 0.61 (95% CI: 0.50, 0.71) for carbohydrate. The correlations between the FFQs and diet records were 0.62 (95% CI: 0.45, 0.74) for dietary GI, 0.77 (95% CI: 0.56, 0.88) for dietary GL, and 0.76 (95% CI: 0.55, 0.88) for carbohydrate after adjustment for within-person variation in the FFQs and diet records. CONCLUSION: In this sample of men, an FFQ measured dietary GI, dietary GL, and carbohydrate with reproducibility and validity similar to other commonly studied nutritional factors.     

Pooled analysis of prospective cohort studies on height, weight, and breast cancer risk

The association between anthropometric indices and the risk of breast cancer was analyzed using pooled data from seven prospective cohort studies. Together, these cohorts comprise 337,819 women and 4,385 incident invasive breast cancer cases. In multivariate analyses controlling for reproductive, dietary, and other risk factors, the pooled relative risk (RR) of breast cancer per height increment of 5 cm was 1.02 (95% confidence interval (CI): 0.96, 1.10) in premenopausal women and 1.07 (95% CI: 1.03, 1.12) in postmenopausal women. Body mass index (BMI) showed significant inverse and positive associations with breast cancer among pre- and postmenopausal women, respectively; these associations were nonlinear. Compared with premenopausal women with a BMI of less than 21 kg/m2, women with a BMI exceeding 31 kg/m2 had an RR of 0.54 (95% CI: 0.34, 0.85). In postmenopausal women, the RRs did not increase further when BMI exceeded 28 kg/m2; the RR for these women was 1.26 (95% CI: 1.09, 1.46). The authors found little evidence for interaction with other breast cancer risk factors. Their data indicate that height is an independent risk factor for postmenopausal breast cancer; in premenopausal women, this relation is less clear. The association between BMI and breast cancer varies by menopausal status. Weight control may reduce the risk among postmenopausal women.     

Dietary glycemic index, dietary glycemic load, and cardiovascular disease in middle-aged and older Swedish men

BACKGROUND: In women, dietary glycemic index (GI) and dietary glycemic load (GL) have been associated with cardiovascular disease; in men, however, the evidence for an association is weaker. OBJECTIVE: We tested the hypothesis that men consuming diets high in GI or GL have a greater risk of cardiovascular disease. DESIGN: At baseline, we assessed dietary GI and dietary GL by using food-frequency questionnaires in 36 246 Swedish men aged 45-79 y without diabetes or prior cardiovascular disease. Participants were followed through inpatient, cause-of-death, and death registries from 1 January 1998 until 31 December 2003 for myocardial infarction, ischemic stroke, hemorrhagic stroke, and cardiovascular mortality and until 31 December 2005 for all-cause mortality. We used Cox models with age as the time scale to estimate relative risks adjusted for cigarette smoking, body mass index, physical activity, demographic characteristics, and nutritional factors. RESULTS: Dietary GI and dietary GL were not associated with myocardial infarction (n = 1324), ischemic stroke (n = 692), cardiovascular mortality (n = 785), or all-cause mortality (n = 2959). Dietary GL was associated with hemorrhagic stroke [n = 165; relative risk = 1.44 comparing extreme quartiles (95% CI: 0.91, 2.27); P for trend = 0.047]. CONCLUSIONS: Dietary GI and dietary GL were not associated with ischemic cardiovascular disease or mortality, but dietary GL was associated with a greater risk of hemorrhagic stroke. Discrepancies between these findings and those of previous studies may be due to variations in the associations by sex or to differences in dietary contributions to GI and GL.     

Carbohydrate nutrition, glycemic index, and the 10-y incidence of cataract

BACKGROUND: Although dietary carbohydrates are thought to play a role in cataractogenesis, few epidemiologic studies have examined links between carbohydrate nutrition and cataract. OBJECTIVES: We investigated the associations between dietary glycemic index (GI), glycemic load (GL), total carbohydrate intake, and 10-y incident nuclear, cortical, and posterior subcapsular cataract. DESIGN: Of 3654 baseline participants in an Australian population aged >/=49 y (1992-1994), 933 were seen after 5 and/or 10 y, had completed a detailed semiquantitative food-frequency questionnaire, had no previous cataract surgery or baseline cataract, and had photographs taken to assess incident cataract with the Wisconsin Cataract Grading System. Dietary information was collected with a validated food questionnaire. GI was calculated from a customized database of Australian foods. GI, GL, and all other nutrients were energy adjusted. Hazard ratios (HRs) and 95% CIs were calculated with the use of discrete logistic models. RESULTS: After age, sex, diabetes, and other factors were controlled for, each SD increase in GI significantly predicted incident cortical cataract (HR: 1.19; 95% CI: 1.01, 1.39). Participants within the highest compared with the lowest quartile of GI were more likely to develop incident cortical cataract (HR: 1.77; 95% CI: 1.13, 2.78; P for trend = 0.035). These findings were similar after excluding participants with diabetes, although they were slightly attenuated and marginally nonsignificant (HR: 1.16; 95% CI: 0.98, 1.37, per SD increase in GI). No association was found between GI and nuclear or posterior subcapsular cataract and between GL or carbohydrate quantity and any cataract subtype. CONCLUSION: In an Australian cohort, poorer dietary carbohydrate quality, reflected by high GI, predicted incident cortical cataract.     

Dietary glycemic load assessed by food-frequency questionnaire in relation to plasma high-density-lipoprotein cholesterol and fasting plasma triacylglycerols in postmenopausal women

BACKGROUND: In metabolic studies, both greater carbohydrate intakes and higher glycemic indexes (GIs) raise fasting triacylglycerol concentrations. In epidemiologic studies, dietary glycemic load (GL) is positively associated with risk of coronary artery disease and type 2 diabetes. OBJECTIVE: We examined both the physiologic relevance of GI and GL and the ability of dietary questionnaires to measure these variables. DESIGN: In the Nurses' Health Study, we measured plasma triacylglycerol concentrations in fasting blood samples from 185 healthy postmenopausal women and HDL-cholesterol concentrations in an additional 95 nonfasting samples. Dietary carbohydrate, GI, and GL were assessed by use of semiquantitative food-frequency questionnaires. The cross-sectional associations between these 3 variables and plasma triacylglycerol and HDL were assessed, with adjustment for potential confounding factors. RESULTS: For the lowest and highest quintiles of GL, the multivariate-adjusted geometric mean triacylglycerol concentrations were 0.98 and 1.75 mmol/L (87 and 155 mg/dL; P for trend < 0.001). Both overall GI (P for trend = 0.03) and carbohydrate (P for trend < 0.01) contributed independently to the strong positive association between GL and fasting triacylglycerol concentrations. GL was also inversely associated with HDL-cholesterol concentrations. For the lowest and highest quintiles of GL, the mean HDL-cholesterol concentrations were 1.50 and 1.34 micromol/L (58 and 52 mg/dL; P for trend = 0.03). The relation between GL and fasting triacylglycerol concentrations differed significantly by body mass index (BMI; in kg/m(2)) categories (P < 0.001 for interaction). For the lowest to the highest quintiles of GL, the mean triacylglycerol concentrations were 0.92 and 2.24 mmol/L (81 and 198 mg/dL) in women with BMIs > 25 (P for trend < 0.001) and 1.02 and 1.42 mmol/L (90 and 126 mg/dL) in women with BMIs < or = 25 (P for trend < 0.001). CONCLUSION: These data support the physiologic relevance of the GL as a potential risk factor for coronary artery disease in free-living women, particularly those prone to insulin resistance. These findings also document the ability of a semiquantitative food-frequency questionnaire to assess dietary GIs and GLs.     

Carbohydrate, glycemic index, and glycemic load and colorectal adenomas in the Prostate, Lung, Colorectal, and Ovarian Screening Study

BACKGROUND: It is possible that high-glycemic-load diets, through their hyperinsulinemic effects, can increase the risk of colorectal cancer. OBJECTIVE: We analyzed data from a cancer screening study to determine whether persons with high-glycemic-load diets would be at an increased risk of distal adenomas. DESIGN: We included subjects with no prior adenoma or cancer from the Prostate, Lung, Colorectal, and Ovarian screening trial and whose results from flexible sigmoidoscopy exams indicated either no lesions (n = 34 817) or >/=1 distal adenoma (n = 3696). We used a 137-item food-frequency questionnaire to assess usual dietary intake over the preceding 12 mo. Using logistic regression analysis, we calculated, separately for men and women, prevalence odds ratios (ORs) and 95% CIs of sigmoidoscopy-detected, distal adenomas for quintiles of energy-adjusted dietary carbohydrate, glycemic index, and glycemic load. RESULTS: ORs decreased with increasing intakes of carbohydrate for both the men and the women in unadjusted models, but these associations were attenuated in multivariate-adjusted models. Among the men, the association remained significant after adjustment (OR: 0.71; 95% CI 0.60, 0.84; P for trend < 0.0001), but in the women it did not (OR: 0.89; 95% CI: 0.73, 1.10; P for trend = 0.30). The results for glycemic index showed no associations in either men or women. Results for glycemic load closely mirrored those for carbohydrate. CONCLUSION: Despite expectations that increasing glycemic load and glycemic index would increase the risk of adenoma, we observed no association in women and even an inverse association in men.     

Dietary glycemic index and load in relation to metabolic risk factors in Japanese female farmers with traditional dietary habits

BACKGROUND: Little is known about the relation of dietary glycemic index (GI) and glycemic load (GL) to metabolic risk factors, particularly in non-Western populations. OBJECTIVE: We examined the cross-sectional associations between dietary GI and GL and several metabolic risk factors in healthy Japanese women with traditional dietary habits. DESIGN: The subjects were 1354 Japanese female farmers aged 20-78 y from 5 regions of Japan. Dietary GI and GL were assessed with a self-administered diet-history questionnaire. Body mass index (BMI) was calculated as weight (kg) divided by the square of height (m). Fasting blood samples were collected for biochemical measurements. RESULTS: The mean dietary GI was 67, and the mean dietary GL (/1000 kcal) was 88 (GI for glucose = 100). White rice (GI = 77) was the major contributor to dietary GI and GL (58.5%). After adjustment for potential dietary and nondietary confounding factors, dietary GI was positively correlated with BMI (n = 1354; P for trend = 0.017), fasting triacylglycerol (n = 1349; P for trend = 0.001), fasting glucose (n = 764; P for trend = 0.022), and glycated hemoglobin (n = 845; P for trend = 0.038). Dietary GL was independently negatively correlated with HDL cholesterol (n = 1354; P for trend = 0.004) and positively correlated with fasting triacylglycerol (P for trend = 0.047) and fasting glucose (P for trend = 0.012). CONCLUSIONS: Both dietary GI and GL are independently correlated with several metabolic risk factors in subjects whose dietary GI and GL were primarily determined on the basis of the GI of white rice.     

Higher glycemic index and glycemic load diet is associated with increased risk of esophageal squamous cell carcinoma: a case-control study

Several studies have indicated the association between intake of foods high in dietary glycemic index (GI) and glycemic load (GL) with an increased risk of digestive tract cancers. We hypothesized that GI and GL may be associated with risk of esophageal squamous cell carcinoma (ESCC) in a high-risk population in Iran. In total, we interviewed 47 cases with incident of ESCC and 96 frequency-matched hospital controls, then calculated the average dietary GI and GL via a validated food frequency questionnaire. Dietary GL was calculated as a function of GI, carbohydrate content, and frequency of intake of certain foods. Dietary GI and GL levels were significantly higher among the ESCC cases compared with the controls (P < .05). After adjustment for potential confounders, those in the highest tertile of dietary GI had 2.95 times higher risk of ESCC compared with those in the lowest (95% confidence interval, 1.68-3.35; P for trend = .002). In addition, being in the highest tertile of dietary GL was positively associated with an ESCC risk (odds ratio, 3.49; 95% confidence interval, 2.98-4.41; P for trend = .001). Findings of the present study indicate that diets with high GI and GL might have potentially unfavorable effects on ESCC risk and suggest a possible role for excess circulating insulin and related insulin-like growth factor 1 in esophageal cancer development.     

Association between dietary carbohydrate,glycemic index,glycemic load,and the prevalence of obesity in Korean men and women

Intake of high–glycemic index (GI) food has been postulated to reduce satiety, resulting in an increased total energy intake and reduced access to body fat as fuel. Thus, we hypothesize that high dietary GI and glycemic load (GL) are associated with an increased prevalence of obesity in the Korean population. Dietary GI and GL were calculated for 933 Korean men and women based on dietary intake assessed by food frequency questionnaires and using a GI table developed from published GI databases in a cross-sectional design. Mean differences in dietary GL and carbohydrate intake between obese and nonobese men were statistically significant after adjusting for covariates (P = .027 and .021, respectively). High dietary GL and carbohydrate intake were negatively associated with the prevalence of obesity among men in a multivariate-adjusted logistic regression model (P for trend = .026 and .036, respectively). Statistically significant effects of dietary GI and GL on the prevalence of obesity among women were observed in a generalized linear model (P = .002 and .042, respectively) and a logistic regression model (P for trend < .001 and = .007, respectively), after adjusting for covariates. Women with higher dietary GI and GL were more likely to be obese, a result consistent with our hypothesis. However, an inverse association for dietary GL and carbohydrate and prevalence of obesity was found in men, suggesting that mechanisms contributing to the prevalence of obesity between sexes may be different.     

Dietary fiber intake, dietary glycemic index and load, and body mass index: a cross-sectional study of 3931 Japanese women aged 18-20 years

OBJECTIVE: Few observational studies have investigated dietary fiber intake and dietary glycemic index (GI) and glycemic load (GL) simultaneously in relation to obesity, particularly in non-Western populations. We examined the associations between dietary fiber intake and dietary GI and GL, and body mass index (BMI) in young Japanese women. DESIGN: Cross-sectional study. SUBJECTS: A total of 3931 female Japanese dietetic students aged 18-20 years from 53 institutions in Japan. METHODS: Dietary fiber intake and dietary GI and GL (GI for glucose=100) were assessed by a validated, self-administered, diet history questionnaire. BMI was calculated from self-reported body weight and height. RESULTS: Mean values of BMI, dietary fiber intake, dietary GI and dietary GL were 21.0 kg/m(2), 6.5 g/4186 kJ, 65.1 and 82.1/4186 kJ, respectively. White rice (GI=77) was the major contributor to dietary GI and GL (45.8%). After controlling for potential dietary and nondietary confounding factors, dietary fiber intake was negatively correlated with BMI (adjusted mean=21.1 kg/m(2) in the lowest and 20.7 kg/m(2) in the highest quintiles; P for trend=0.0007). Conversely, dietary GI and GL were independently positively correlated with BMI (20.8 and 21.2 kg/m(2); P for trend=0.03, and 20.5 and 21.5 kg/m(2); P for trend=0.0005, respectively). CONCLUSIONS: Dietary fiber intake showed an independent negative association with BMI, and dietary GI and GL showed an independent positive association with BMI among relatively lean young Japanese women.