Glycemic index, glycemic load, and cereal fiber intake and risk of type 2 diabetes in US black women

BACKGROUND: Previous studies of carbohydrate quality and risk of type 2 diabetes mellitus have yielded inconsistent findings. Because diet is in part culturally determined, a study of dietary factors in US black women is of interest. METHODS: We used data from the Black Women's Health Study, a prospective cohort study of 59,000 US black women, to examine the association of glycemic load, glycemic index, and cereal fiber with risk of type 2 diabetes. Diet was assessed at baseline in 1995 with a modified version of the National Cancer Institute-Block food frequency questionnaire. RESULTS: During 8 years of follow-up, there were 1,938 incident cases of diabetes. Cox proportional hazards models were used to estimate incidence rate ratios (IRRs) for quintiles of dietary factors, while controlling for lifestyle and dietary factors. Glycemic index was positively associated with the risk of diabetes: the IRR for the highest quintile relative to the lowest was 1.23 (95% confidence interval [CI], 1.05-1.44). Cereal fiber intake was inversely associated with risk of diabetes, with an IRR of 0.82 (95% CI, 0.70-0.96) for the highest vs lowest quintiles of intake. Stronger associations were seen among women with a body mass index (calculated as weight in kilograms divided by height in meters squared) lower than 25: IRRs for the highest vs lowest quintile were 1.91 (95% CI, 1.16-3.16) for glycemic index (P value for interaction, .12) and 0.41 (95% CI, 0.24-0.72) for cereal fiber intake (P value for interaction, .05). CONCLUSION: Increasing cereal fiber in the diet may be an effective means of reducing the risk of type 2 diabetes, a disease that has reached epidemic proportions in black women.     

Dietary glycemic index, glycemic load, and intake of carbohydrate and rice in relation to risk of mortality from stroke and its subtypes in Japanese men and women

We assessed the relationship of the dietary glycemic index (GI), glycemic load (GL), and intake of carbohydrate and rice, and risk of mortality from stroke and its subtypes. The cohort consisted of 12 561 men and 15 301 women residing in Takayama, Japan, in 1992. At the baseline, a food frequency questionnaire was administered; and the dietary GI, GL, and intake of carbohydrates and rice were estimated. Deaths from stroke occurring in the cohort were prospectively noted until 1999 with data from the office of the National Vital Statistics. The risk of mortality from stroke was assessed with a Cox proportional hazard model after adjusting for age; body mass index; smoking status; physical activity; history of hypertension; education; and intake of total energy, alcohol, dietary fiber, salt, and total fat. The risk of stroke subtypes was assessed in the age-adjusted model. The hazard ratios of total stroke comparing the highest vs the lowest quartiles of the dietary GI were 0.78 (95% confidence interval [CI], 0.41-1.47) with P_trend = .50 in men and 2.09 (95% CI, 1.01-4.31) with P_trend = .10 in women. Among women, the association was also significant with the risk of ischemic stroke (hazard ratio = 2.45; 95% CI, 1.01-5.92; P_trend = .03); and a significant positive trend was also observed between dietary GL and mortality from hemorrhagic stroke (P_trend = .05). The current study implies that diets with a high dietary GI increase the risk of mortality from stroke among Japanese women.     

High dietary glycemic load and glycemic index increase risk of cardiovascular disease among middle-aged women: a population-based follow-up study.

OBJECTIVES: The goal of this work was to assess whether high dietary glycemic load and glycemic index are associated with an increased risk of cardiovascular disease (CVD). BACKGROUND: The associations of dietary glycemic index and glycemic load with risk of CVD are not well established, particularly in populations consuming modest glycemic load diets. Moreover, risk may differ between lean and overweight subjects. METHODS: Associations of glycemic index and glycemic load with incident CVD were examined in a prospective cohort of 15,714 Dutch women age 49 to 70 years without diabetes or CVD. Dietary glycemic index and glycemic load were calculated using the glycemic index, carbohydrate content, and frequency of intake of individual foods. RESULTS: During 9 +/- 2 years of follow-up, 556 cases of coronary heart disease (CHD) and 243 cases of cerebrovascular accident (CVA) occurred. Dietary glycemic load (mean = 100; SD = 17) was associated with increased risk of CVD, adjusted for CVD risk factors and dietary variables, with a hazard ratio (HR) for the highest against lowest quartile of 1.47 (95% confidence interval [CI] 1.04 to 2.09; p(trend) = 0.03). Similar results were observed for dietary glycemic index with a corresponding HR of 1.33 (95% CI 1.07 to 1.67; p(trend) = 0.02). Glycemic load tended to be associated with both CHD (HR 1.44; 95% CI 0.95 to 2.19; p(trend) = 0.14) and CVA (HR 1.55; 95% CI 0.81 to 2.97; p(trend) = 0.10), but glycemic index only with CHD (HR 1.44; 95% CI 1.10 to 1.89; p(trend) = 0.01). Among overweight women (body mass index >25 kg/m2), glycemic load was associated with CVD (1.78; 95% CI 1.11 to 2.85; p(trend) = 0.04), but not among normal weight women (p(interaction) = 0.19). Body mass index did not modify the association of glycemic index with CVD. CONCLUSIONS: Among women consuming modest glycemic load diets, high dietary glycemic load and glycemic index increase the risk of CVD, particularly for overweight women.     

Alcohol drinking patterns and risk of type 2 diabetes mellitus among younger women

OBJECTIVE: To examine the relationship between alcohol consumption and the incidence of type 2 diabetes mellitus among relatively young and middle-aged women. METHODS: In a prospective study, 109 690 women, aged 25 to 42 years, without a history of coronary heart disease, stroke, cancer, or diabetes mellitus completed a detailed lifestyle and medical history questionnaire in 1989. During 10 years of follow-up, we documented 935 incident cases of type 2 diabetes mellitus. RESULTS: We found a nonlinear relationship between alcohol consumption and risk of type 2 diabetes mellitus after adjustment for multiple confounders, including body mass index, smoking, physical activity, and family history of diabetes mellitus (quadratic trend P =.003). Compared with lifelong abstainers, the adjusted relative risks (95% confidence intervals) were 0.80 (0.66-0.96) for those consuming 0.1 to 4.9 g/d, 0.67 (0.50-0.89) for those consuming 5.0 to 14.9 g/d, 0.42 (0.20-0.90) for those consuming 15.0 to 29.9 g/d, and 0.78 (0.34-1.78) for those consuming 30.0 g/d or more. Further adjustment for dietary factors, including glycemic load, trans-fatty acid, polyunsaturated fat, and total fiber intake, did not appreciably alter these findings. The inverse association with light to moderate drinking was most apparent in women who reported wine or beer drinking. Women who reported 30.0 g/d or more of liquor intake showed a significantly increased risk of diabetes mellitus compared with those who did not report liquor intake (adjusted relative risk, 2.50; 95% confidence interval, 1.00-6.23). CONCLUSION: Light to moderate alcoholic beverage consumption may be associated with a lower risk of type 2 diabetes mellitus among women aged 25 to 42 years, although this benefit may not persist at higher levels.     

Glycemic load, glycemic index, and carbohydrate intake in relation to risk of cholecystectomy in women

BACKGROUND & AIMS: High-carbohydrate diets with a high glycemic response may exacerbate the metabolic consequences of the insulin-resistance syndrome. The effect on the incidence of gallstone disease is not clear. METHODS: We examined the associations between high-carbohydrate diets with a high glycemic response and the risk of cholecystectomy in a cohort of women who were aged from 35 to 61 years in 1984 and had no history of gallstone disease. As part of the Nurses' Health Study, the women reported on questionnaires mailed to them every 2 years both their carbohydrate intake and whether they had undergone cholecystectomy. RESULTS: During 16 years of follow-up, we ascertained 5771 new cases of cholecystectomy. After adjusting for age and other known or suspected risk factors in a multivariate model, the relative risk for the highest compared with the lowest quintile of dietary carbohydrate was 1.35 (95% CI: 1.17-1.55, P for trend < .0001). The relative risks for the highest compared with the lowest quintile were 1.50 for glycemic load (95% CI: 1.32-1.71, P for trend < .0001) and 1.32 for glycemic index (95% CI: 1.20-1.45, P for trend < .0001). Independent positive associations were also seen for intakes of starch and sucrose. CONCLUSIONS: Our findings suggest that a higher intake of carbohydrate, dietary glycemic load, and glycemic index may enhance risk of cholecystectomy in women.     

The glycemic index and cardiovascular disease risk

Postprandial hyperglycemia is increasingly recognized as an independent risk factor for cardiovascular disease. Glycemic “spikes” may adversely affect vascular structure and function via multiple mechanisms, including (acutely and/or chronically) oxidative stress, inflammation, low-density lipoprotein oxidation, protein glycation, and procoagulant activity. Postprandial glycemia can be reliably predicted by considering both the amount and type of carbohydrate. In particular, the glycemic index (GI), a measure of postprandial glycemic potency weight for weight of carbohydrate, has provided insights that knowledge of the sugar or starch content has not. In prospective observational studies, dietary GI and/or glycemic load independently predict cardiovascular disease, with relative risk ratios of 1.2 to 1.7 comparing highest and lowest quintiles. In randomized controlled trials in overweight subjects, diets based on low-GI carbohydrates have produced better cardiovascular-related outcomes than conventional low-fat diets. Taken together, the findings suggest that health professionals may be able to improve cardiovascular outcomes by recommending the judicious use of low-GI/glycemic load foods.     

Dietary glycemic index and risk of type 2 diabetes mellitus in middle-aged Japanese men

This cohort study investigated the association between dietary glycemic index (GI), glycemic load (GL), and the incidence of type 2 diabetes mellitus in middle-aged Japanese men, and the effect of insulin resistance and pancreatic B-cell function on the association. Participants were 1995 male employees of a metal products factory in Japan. Dietary GI and GL were assessed using a self-administered diet history questionnaire. The incidence of diabetes was detected in annual medical examinations over a 6-year period. The association between GI, GL, and the incidence of diabetes was evaluated using Cox proportional hazards models. During the study, 133 participants developed diabetes. Age- and body mass index-adjusted hazard ratios across the GI quintiles were 1.00 (reference), 1.62, 1.50, 1.68, and 1.80; and those of GL were 1.00 (reference), 1.07, 1.48, 0.95, and 0.98. The hazard ratio for the highest GI quintile was significantly greater than that for the lowest quintile. The influence of GI was more pronounced in the lowest insulin resistance subgroups. GI and pancreatic B-cell function were independently associated with the incidence of type 2 diabetes mellitus; participants with low B-cell function and the highest tertile of GI had the highest risk of diabetes. Dietary GI is associated with the incidence of diabetes in middle-aged Japanese men. GI and B-cell function were independently associated with incidence of diabetes.     

Use of the glycemic index for weight loss and glycemic control: A review of recent evidence

This article summarizes current findings regarding the use of low-glycemic index (GI) diets for weight loss and type 2 diabetes control. Results from cross-sectional studies evaluating the association between dietary GI and body mass index had equivocal results, especially when dietary fiber was included in the model. Of five prospective cohort studies, two reported increased risk of type 2 diabetes diagnosis with higher dietary GI or glycemic load (GL). Risk of type 2 diabetes appeared to have a stronger association with carbohydrate intake or GL than with GI. Evidence from intervention studies using a low-GI approach for weight loss produced inconsistent results, especially for longer-term studies. In intervention studies with type 2 diabetes patients, consumption of a low-GI diet resulted in lower hemoglobin A_1c concentrations in participants of shorter-term studies. Recent evidence adds to the controversy regarding the effectiveness of consuming low-GI diets for glycemic control and weight reduction.     

Influence of high glycemic index and glycemic load diets on blood pressure during adolescence

We aimed to prospectively examine the association between the glycemic index and glycemic load of foods consumed and the dietary intakes of carbohydrates, sugars, fiber, and principal carbohydrate-containing food groups (eg, breads, cereals, and sugary drinks) with changes in blood pressure during adolescence. A total of 858 students aged 12 years at baseline (422 girls and 436 boys) were examined from 2004-2005 to 2009-2011. Dietary data were assessed from validated semiquantitative food frequency questionnaires. Blood pressure was measured using a standard protocol. In girls, after adjusting for age, ethnicity, parental education, parental history of hypertension, baseline height, baseline blood pressure, change in body mass index, and time spent in physical and sedentary activities, each 1-SD (1-SD = 7.10 g/d) increase in baseline dietary intake of total fiber was associated with a 0.96-, 0.62-, and 0.75-mmHg decrease in mean systolic (P = 0.02), diastolic (P = 0.01), and arterial blood pressures (P = 0.002), respectively, 5 years later. In girls, each 1-SD increase in dietary glycemic index, glycemic load, carbohydrate, and fructose was concurrently related to increases of 1.81 (P = 0.001), 4.02 (P = 0.01), 4.74 (P = 0.01), and 1.80 mm Hg (P = 0.03) in systolic blood pressure, respectively, >5 years. Significant associations between carbohydrate nutrition variables and blood pressure were not observed among boys. Excessive dietary intake of carbohydrates, specifically from high glycemic index/glycemic load foods, could adversely influence blood pressure, particularly in girls, whereas fiber-rich diets may be protective against elevated blood pressure during adolescence.     

Dietary glycemic load and atherothrombotic risk

Hyperglycemia and hyperinsulinemia are central features of the metabolic syndrome and type 2 diabetes mellitus, which contribute to the pathogenesis of coronary heart disease (CHD). Recent data indicate that increased dietary glycemic load (GL) due to replacing fats with carbohydrates or increasing intake of rapidly absorbed carbohydrates (ie, high glycemic index [GI]) can create a self-perpetuating insulin resistance state and predicts greater CHD risk. In this paper, we discuss the historic development of the GI and GL concepts and summarize metabolic experiments and epidemiologic observations relating to clinical utilities of these measures. On balance, increased consumption of low-GI foods leads to improvements in glycemia and dyslipidemia in metabolic studies, and a low-GL diet has been associated with lower risk of type 2 diabetes and CHD in prospective cohort studies. We conclude that decreasing dietary GL by reducing the intake of high-glycemic beverages and replacing refined grain products and potatoes with minimally processed plant-based foods such as whole grains, fruits, and vegetables may reduce CHD incidence in sedentary individuals and populations with a high prevalence of overweight. Because of advances in food-processing technologies and changes in ingredients in our food supply, the composition and physiologic effects of foods are likely to change over time. Future efforts should continue to quantify and monitor the metabolic impacts of different foods, and such information should be routinely incorporated into long-term prospective studies to allow for the assessment of the interactive effects of diets and other metabolic determinants on chronic disease risk.     

Glycemic index and serum high-density lipoprotein cholesterol concentration among us adults

BACKGROUND: Dietary glycemic index, an indicator of the ability of the carbohydrate to raise blood glucose levels, and glycemic load, the product of glycemic index and carbohydrate intake, have been positively related to risk of coronary heart disease. However, the relationships between glycemic index and glycemic load and high-density lipoprotein cholesterol (HDL-C) concentration in the US population are unknown. METHODS: Using data from 13 907 participants aged 20 years and older in the Third National Health and Nutrition Examination Survey (1988-1994), we examined the relationships between glycemic index and glycemic load, which were determined from a food frequency questionnaire and HDL-C concentration. RESULTS: The age-adjusted mean HDL-C concentrations for increasing quintiles of glycemic index distribution were 1.38, 1.32, 1.30, 1.26, and 1.27 mmol/L (P<.001 for trend). (To convert millimoles per liter to milligrams per deciliter, divide by 0.0259.) After additional adjustment for sex, ethnicity, education, smoking status, body mass index, alcohol intake, physical activity, energy fraction from carbohydrates and fat, and total energy intake, the mean HDL-C concentrations for ascending quintiles of glycemic index were 1.36, 1.31, 1.30, 1.27, and 1.28 mmol/L (P<.001 for trend). Adjusting for the same covariates and considering glycemic index as a continuous variable, we found a change in HDL-C concentration of -0.06 mmol/L per 15-unit increase in glycemic index (P<.001). The multiple R(2) for the model was 0.23. Similarly, the multivariate-adjusted mean HDL-C concentrations for ascending quintiles of glycemic load distribution were 1.35, 1.31, 1.31, 1.30, and 1.26 mmol/L (P<.001 for linear trend). The inverse relationships between glycemic index and glycemic load and HDL-C persisted across all subgroups of participants categorized by sex or body mass index. CONCLUSIONS: These findings from a nationally representative sample of US adults suggest that high dietary glycemic index and high glycemic load are associated with a lower concentration of plasma HDL-C.     

Relative validity of a glycemic index extended food-frequency questionnaire

Background and aimsThe dietary glycemic index (GI) and glycemic load (GL) are increasingly recognized as important for the prevention and management of diabetes mellitus. To extend the portfolio of assessment methods for large-scale epidemiological studies, we propose a GI-specific addition to an already established FFQ.Methods and resultsThe German version of the EPIC-FFQ was extended by GI-specific questions for major carbohydrate sources varying notably in GI (breakfast cereals, bread, pasta, rice, potato etc.). We performed relative validation analyses comparing the GI-extended FFQ to three to four 3-day weighted dietary records (3-d WDR) in 100 middle-aged individuals with diabetes mellitus participating in the German Diabetes Study (GDS). Level of agreement between the two methods was assessed by correlation and cross-classification analyses as well as Bland-Altman-Plots, conducted separately for women and men.Spearman correlation analysis for female participants suggested good agreement between the GI-extended FFQ and 3-d WDRs for energy adjusted dietary GL (r = 0.52, p = 0.0004). For both women and men, agreement with the estimations of dietary GI, GL (for men) and carbohydrates from low and higher-GI food sources from the GI-extended FFQ was acceptable (r: 0.28–0.45). Classification of the dietary GI and GL in the opposite quartile was <10% comparing the GI-extended FFQ and 3-d WDR. Bland-Altman plots suggested a tendency for an overestimation of the dietary GI from the GI-extended FFQ in the lower GI-ranges, particularly for men.ConclusionCompared to the 3-d WDR, the GI-extended FFQ showed a moderate to good relative validity for parameters of carbohydrate quality.     

Associations of dietary glycemic index and glycemic load with glucose intolerance in Iranian adults

This study examined the associations of dietary glycemic index and glycemic load with glucose intolerance in Iranian adults. The study had a cross-sectional design and was performed as a secondary analysis on data obtained from the Isfahan Healthy Heart Program (2000–2001). Data on food intake using a 24-hour recall and blood parameters of a subsample of 960 adults age ≥19 years were used (436 Men, 524 Women; age: 38.2?±?15.4 year). We identified a positive significant association of fasting and postprandial blood glucose (P?<?0.001), body mass index (P?<?0.001), and age (P?<?0.001) with diabetes mellitus, but found no statistically significant associations of dietary glycemic index and glycemic load with diabetes mellitus after adjusting for body mass index, age, gender, and smoking as confounding factors. We concluded that a low glycemic index diet is not associated with the prevalence of glucose intolerance in our sample.     

Meta-analysis of dietary glycemic load and glycemic index in relation to risk of coronary heart disease

A high glycemic diet may increase cardiovascular risk, yet whether the risk differs by gender or adiposity is inconclusive. Our goal was to determine the associations between dietary glycemic load (GL) and glycemic index (GI), and coronary heart disease (CHD) risk by conducting a meta-analysis of prospective studies. We searched the PubMed and Embase databases in July 2011 to identify eligible studies. The random-effects model was used to calculate pooled relative risks (RRs) comparing the highest categories of exposure to the lowest. Prespecified subgroup analyses were performed by gender and body mass index. We identified 8 prospective studies for meta-analysis, consisting of 220,050 participants and 4,826 incident CHD cases. Pooled RRs of CHD in relation to dietary GL were 1.08 (95% confidence interval [CI] 0.92 to 1.27) for men, 1.69 (95% CI 1.32 to 2.16) for women, and 1.36 (95% CI 1.13 to 1.63) for men and women combined. For dietary GI, corresponding pooled RRs were 0.99 (95% CI 0.84 to 1.16), 1.26 (95% CI 1.12 to 1.43), and 1.13 (95% CI 1.00 to 1.28), respectively. Limited evidence suggested the associations appeared more evident in the overweight and obese. There was no indication of publication bias. In conclusion, high dietary GL and GI significantly increased the risk of CHD in women but not in men, and the unfavorable effects may be more pronounced in overweight and obese patients. Further studies are needed to verify these findings and elucidate the underlying mechanisms.     

Dietary patterns, meat intake, and the risk of type 2 diabetes in women

BACKGROUND: Although obesity is the most important risk factor for type 2 diabetes, evidence is emerging that certain foods and dietary factors may be associated with diabetes. To examine the association between major dietary patterns and risk of type 2 diabetes mellitus in a cohort of women. METHODS: We prospectively assessed the associations between major dietary patterns and risk of type 2 diabetes in women. Dietary information was collected in 1984, 1986, 1990, and 1994 from 69,554 women aged 38 to 63 years without a history of diabetes, cardiovascular disease, or cancer in 1984. We conducted factor analysis and identified 2 major dietary patterns: "prudent" and "Western." We then calculated pattern scores for each participant and examined prospectively the associations between dietary pattern scores and type 2 diabetes risks. RESULTS: The prudent pattern was characterized by higher intakes of fruits, vegetables, legumes, fish, poultry, and whole grains, while the Western pattern included higher intakes of red and processed meats, sweets and desserts, french fries, and refined grains. During 14 years of follow-up, we identified 2699 incident cases of type 2 diabetes. After adjusting for potential confounders, we observed a relative risk for diabetes of 1.49 (95% confidence interval [CI], 1.26-1.76, P for trend, <.001) when comparing the highest to lowest quintiles of the Western pattern. Positive associations were also observed between type 2 diabetes and red meat and other processed meats. The relative risk for diabetes for every 1-serving increase in intake is 1.26 (95% CI, 1.21-1.42) for red meat, 1.38 (95% CI, 1.23-1.56) for total processed meats, 1.73 (95% CI, 1.39-2.16) for bacon, 1.49 (95% CI, 1.04-2.11) for hot dogs, and 1.43 (95% CI, 1.22-1.69) for processed meats. CONCLUSION: The Western pattern, especially a diet higher in processed meats, may increase the risk of type 2 diabetes in women.     

Relationship between premenopausal dietary intake and postmenopausal subclinical atherosclerosis

OBJECTIVES: This study examines the association of premenopausal dietary intake with postmenopausal subclinical atherosclerosis. DESIGN: A prospective population-based cohort of 401 premenopausal women from the Healthy Women Study. Baseline premenopausal dietary intake was determined with the use of single 24-h recall. Coronary and aortic calcium scores were measured by electron beam computed tomography 8 years after menopause, and carotid plaque index was measured by carotid ultrasound scan 5 years after menopause. RESULTS: Prevalence of coronary, aortic, and carotid subclinical atherosclerosis were 47.3%, 75.4%, and 52.1%, respectively. In unadjusted analysis, the relative risks (RR) of saturated fat intake for coronary calcification in second, third and highest quartile groups compared to the lowest were 1.82 (95% confidence interval, 1.00-3.30), 1.49 (0.82-2.70), and 1.99 (1.09-3.62), while those of carbohydrate intake were 0.48 (95% confidence interval, 0.26-0.88), 0.47 (0.26-0.86), and 0.35 (0.19-0.64), respectively. None of the dietary components were significantly associated with aortic calcification or carotid plaque. CONCLUSION: The association between premenopausal dietary intake and postmenopausal subclinical atherosclerosis supports the recommended premenopausal dietary intervention for the prevention of cardiovascular disease.     

Fiber and magnesium intake and incidence of type 2 diabetes: a prospective study and meta-analysis

BACKGROUND: Prospective studies on fiber and magnesium intake and risk of type 2 diabetes mellitus were inconsistent. We examined associations between fiber and magnesium intake and risk of type 2 diabetes and summarized existing prospective studies by meta-analysis. METHODS: We conducted a prospective cohort study of 9702 men and 15 365 women aged 35 to 65 years who were observed for incident diabetes from 1994 to 2005. Dietary intake of fiber and magnesium were measured with a validated food-frequency questionnaire. We estimated the relative risk (RR) by means of Cox proportional hazards analysis. We searched PubMed through May 2006 for prospective cohort studies of fiber and magnesium intake and risk of type 2 diabetes. We identified 9 cohort studies of fiber and 8 studies of magnesium intake and calculated summary RRs by means of a random-effects model. RESULTS: During 176 117 person-years of follow-up, we observed 844 incident cases of type 2 diabetes in the European Prospective Investigation Into Cancer and Nutrition-Potsdam. Higher cereal fiber intake was inversely associated with diabetes risk (RR for extreme quintiles, 0.72 [95% confidence interval [CI], 0.56-0.93]), while fruit fiber (0.89 [95% CI, 0.70-1.13]) and vegetable fiber (0.93 [95% CI, 0.74-1.17]) were not significantly associated. Meta-analyses showed a reduced diabetes risk with higher cereal fiber intake (RR for extreme categories, 0.67 [95% CI, 0.62-0.72]), but no significant associations for fruit (0.96 [95% CI, 0.88-1.04]) and vegetable fiber (1.04 [95% CI, 0.94-1.15]). Magnesium intake was not related to diabetes risk in the European Prospective Investigation Into Cancer and Nutrition-Potsdam (RR for extreme quintiles, 0.99 [95% CI, 0.78-1.26]); however, meta-analysis showed a significant inverse association (RR for extreme categories, 0.77 [95% CI, 0.72-0.84]). CONCLUSION: Higher cereal fiber and magnesium intakes may decrease diabetes risk.     

Dietary glycemic index, dietary glycemic load, blood lipids, and C-reactive protein

Carbohydrate quantity and quality may influence the risk of cardiovascular disease through blood lipid concentrations and inflammation. We measured dietary glycemic index (GI) and dietary glycemic load (GL) among 18137 healthy women > or = 45 years old without diagnosed diabetes using a food-frequency questionnaire. We assayed fasting total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol; LDL/HDL cholesterol ratio; triacylglycerols (TG); and C-reactive protein (CRP). We evaluated associations with dietary GI and GL using a cross-sectional design, adjusting for age, body mass index, lifestyle factors, and other dietary factors. Dietary GI was significantly associated with HDL and LDL cholesterol, LDL/HDL cholesterol ratio, TG, and CRP (comparing top to bottom quintile difference in HDL cholesterol = -2.6 mg/dL, LDL cholesterol = 2.2 mg/dL, LDL/HDL cholesterol ratio = 0.16, TG = 12 mg/dL, and CRP = 0.21 mg/L). Dietary GL was associated with HDL cholesterol, LDL/HDL cholesterol ratio, and TG (comparing top to bottom quintile HDL cholesterol = -4.9 mg/dL, LDL/HDL cholesterol ratio = 0.24, and TG = 13 mg/dL). Differences in blood lipids and CRP between extreme quintiles of dietary GI and GL were small, but may translate into a clinically meaningful difference in cardiovascular risk.     

Evidence-based guideline of the German Nutrition Society: carbohydrate intake and prevention of nutrition-related diseases

The relative contribution of nutrition-related chronic diseases to the total disease burden of the society and the health care costs has risen continuously over the last decades. Thus, there is an urgent necessity to better exploit the potential of dietary prevention of diseases. Carbohydrates play a major role in human nutrition - next to fat, carbohydrates are the second biggest group of energy-yielding nutrients. Obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease and cancer are wide-spread diseases, in which carbohydrates could have a pathophysiologic relevance. Correspondingly, modification of carbohydrate intake could have a preventive potential. In the present evidence-based guideline of the German Nutrition Society, the potential role of carbohydrates in the primary prevention of the named diseases was judged systematically. The major findings were: a high carbohydrate intake at the expense of total fat and saturated fatty acids reduces the concentrations of total, LDL and HDL cholesterol. A high carbohydrate consumption at the expense of polyunsaturated fatty acids increases total and LDL cholesterol, but reduces HDL cholesterol. Regardless of the type of fat being replaced, a high carbohydrate intake promotes an increase in the triglyceride concentration. Furthermore, a high consumption of sugar-sweetened beverages increases the risk of obesity and type 2 diabetes mellitus, whereas a high dietary fibre intake, mainly from whole-grain products, reduces the risk of obesity, type 2 diabetes mellitus, dyslipoproteinaemia, cardiovascular disease and colorectal cancer at varying evidence levels. The practical consequences for current dietary recommendations are presented.     

Carbohydrate quality,glycemic index,glycemic load and cardiometabolic risks in the US,Europe and Asia: A dose–response meta-analysis

Background and aimsDespite the proven evidence of high glycemic index (GI) and glycemic load (GL) diets to increase cardiometabolic risks, knowledge about the meta-evidence for carbohydrate quality within world geographic regions is limited. We conducted a meta-analysis to synthesize the evidence of GI/GL studies and carbohydrate quality, gathering additional exposures for carbohydrate, high glycemic carbohydrate, total dietary fiber, and cereal fiber and risks for type 2 diabetes (T2DM), coronary heart disease (CHD), stroke, and mortality, grouped into the US, Europe, and Asia. Secondary aims examined cardiometabolic risks in overweight/obese individuals, by sex, and dose–response dietary variable trends.Methods and results40-prospective observational studies from 4-Medline bibliographical databases (Ovid, PubMed, EBSCOhost, CINAHL) were search up to November 2019. Random-effects hazard ratios (HR) and 95% confidence intervals (CI) for highest vs. lowest categories and continuous form combined were reported. Heterogeneity (I²>50%) was frequent in US GI/GL studies due to differing study characteristics. Increased risks ((HR_GI,T2DM,US=1.14;CI:1.06,1.21), HR_GL,T2DM,US=1.02 (1.01, 1.03)), HR_GI,T2DM,Asia=1.25;1.02,1.53), and HR_GL,T2DM,Asia=1.37 (1.17, 1.60)) were associated with cardiometabolic diseases. GI/GL in overweight/obese females had the strongest magnitude of risks in US-and Asian studies. Total dietary fiber (HRT2DM,US = 0.92;0.88,0.96) and cereal fiber (HR_T2DM,US = 0.83;0.77,0.90) decreased risk of developing T2DM. Among females, we found protective dose–response risks for total dietary fiber (HR_{5g-total-dietary-fiber,T2DM,US} = 0.94;0.92,0.97)_, but cereal fiber showed better ability to lower T2DM risk (HR_{5g-cereal-fiber},_T2DM,US = 0.67;0.60,0.74). Total dietary-and cereal fibers' dose–response effects were nullified by GL, but not so for cereal fiber with GI.ConclusionsOverweight/obese females could shift their carbohydrate intake for higher cereal fiber to decrease T2DM risk, but higher GL may cancel-out this effect.