Reproducibility and relative validity of dietary glycaemic index and glycaemic load assessed by the food-frequency questionnaire used in the Dutch cohorts of the European Prospective Investigation into Cancer and Nutrition

A healthy dietary pattern is associated with microbiota diversity in recently diagnosed bipolar patients: The Bipolar Netherlands Cohort (BINCO) study

BACKGROUND

Diet largely impacts the gut microbiota, and may affect mental and somatic health via the gut-brain axis. As such, the relationship between diet and the microbiota in Bipolar Disorder (BD) could be of importance, but has not been studied before. The aim was therefore to assess whether dietary quality is associated with the gut microbiota diversity in patients with recently diagnosed BD, and whether changes occur in dietary quality and microbiota diversity during their first year of treatment.

METHODS

Seventy recently (<1 year) diagnosed patients with BD were included in the "Bipolar Netherlands Cohort" (BINCO), and a total of 45 participants were assessed after one year. A 203-item Food Frequency Questionnaire (FFQ) data yielded the Dutch Healthy index (DHD-15), and the microbiota composition and diversity of fecal samples were characterized by 16S rRNA gene amplicon sequencing at baseline and 1-year follow-up. Associations and changes over time were analyzed using multivariate regression analyses and t-tests for paired samples.

RESULTS

Included patients had a mean age of 34.9 years (SD ± 11.2), and 58.6 % was female. Alpha diversity (Shannon diversity index), richness (Chao1 index) and evenness (Pielou's Evenness Index) were positively associated with the DHD-15 total score, after adjustment for sex, age and educational level (beta = 0.55; P < 0.001, beta = 0.39; P = 0.024, beta = 0.54; P = 0.001 respectively). The positive correlations were largely driven by the combined positive effect of fish, beans, fruits and nuts, and inverse correlations with alcohol and processed meats. No significant changes were found in DHD-15 total score, nor in microbiota diversity, richness and evenness indexes during one year follow-up and regular treatment.

CONCLUSION

A healthy and varied diet is associated with the diversity of the microbiota in BD patients. Its potential consequences for maintaining mood stability and overall health should be studied further.

Relative validity of a glycemic index extended food-frequency questionnaire

BACKGROUND AND AIMS

The 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 RESULTS

The 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.

CONCLUSION

Compared to the 3-d WDR, the GI-extended FFQ showed a moderate to good relative validity for parameters of carbohydrate quality.

Validation of estimated glycaemic index and glycaemic load, stratified by race, in the Adventist Health Study-2 (AHS-2)

OBJECTIVE

Few studies have validated FFQ estimates of dietary glycaemic index (GI) and load (GL). We investigated how well our estimates of overall GI and GL from FFQs correlate with estimates from repeated 24 h recall data to validate overall GI and GL in the Adventist Health Study-2 (AHS-2).

DESIGN

The AHS-2 is a prospective population-based cohort of 95 873 Seventh-day Adventist adult church members enrolled from 2002 to 2007 to investigate diet, cancer and mortality.

SETTING

A 204-item FFQ was used to assess race- and gender-specific validity of GI and GL and 24 h recall data, from the calibration sub-study, were used as the reference.

PARTICIPANTS

The 734 calibration study participants were randomly selected by church and included approximately equal numbers of blacks and whites but were otherwise similar to the whole cohort with respect to gender, age, education and vegetarian status.

RESULTS

The deattenuated correlation coefficients for overall GI ranged from 0·19 (95 % CI -0·06, 0·53) in black men to 0·46 (95 % CI 0·40, 0·60) in black women, with both non-black men and women falling between those values (0·45 (95 % CI 0·35, 0·65) and 0·38 (95 % CI 0·27, 0·57), respectively). GL correlations were somewhat higher for all study participants. When looking at the entire cohort, the deattenuated validity correlation value for overall GI was (r 0·38, 95 % CI 0·36, 0·47) and GL was (r 0·39, 95 % CI 0·34, 0·49).

CONCLUSIONS

Our findings support the cautious use of our FFQ in epidemiological studies when assessing associations of overall GI and GL with disease risk. However, observed differences by race should be considered when interpreting results.

High dietary glycemic load is associated with higher concentrations of urinary advanced glycation endproducts: the Cohort on Diabetes and Atherosclerosis Maastricht (CODAM) Study

BACKGROUND

Advanced glycation endproducts (AGEs) and their precursors (dicarbonyls) are associated with the progression of diseases such as diabetes and cardiovascular disease. Plasma concentrations of dicarbonyls methylglyoxal (MGO), glyoxal (GO), and 3-deoxyglucosone (3-DG) are increased after an oral glucose load indicating that consumption of diets high in carbohydrates may induce the endogenous formation of dicarbonyls and AGEs.

OBJECTIVE

To examine the associations of dietary glycemic index (GI) and glycemic load (GL) with concentrations of dicarbonyls and AGEs in plasma and urine.

METHODS

Cross-sectional analyses were performed in a human observational cohort [Cohort on Diabetes and Atherosclerosis Maastricht (CODAM), n = 494, 59 ± 7 y, 25% type 2 diabetes]. GI and GL were derived from FFQs. Dicarbonyls and AGEs were measured in the fasting state by ultra-performance liquid chromatography-tandem MS. MGO, GO, and 3-DG and protein-bound Nε-(carboxymethyl)lysine (CML), Nε-(1-carboxyethyl)lysine (CEL), and pentosidine were measured in plasma. Free forms of CML, CEL, and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were measured in both plasma and urine. Multiple linear regression was performed with dicarbonyls and AGEs as dependent variables, and dietary GI or GL as main independent variables (all standardized). Models were adjusted for health and lifestyle factors, dietary factors, and reciprocally for GI and GL. As this was an explorative study, we did not adjust for multiple testing.

RESULTS

GI was not associated with any of the dicarbonyls or AGEs. GL was positively associated with free urinary MG-H1 (β = 0.34; 95% CI: 0.12, 0.55). Furthermore, GL was positively associated with free plasma MG-H1 and free urinary CML (β = 0.23; 95% CI: 0.02, 0.43; and β = 0.28; 95% CI: 0.06, 0.50), but these associations were not independent of dietary AGE intake.

CONCLUSIONS

A habitual diet higher in GL is associated with higher concentrations of free urinary MG-H1. This urinary AGE is most likely a reflection of AGE accumulation and degradation in tissues, where they may be involved in tissue dysfunction.

The Glycaemic Index-Food-Frequency Questionnaire: Development and Validation of a Food Frequency Questionnaire Designed to Estimate the Dietary Intake of Glycaemic Index and Glycaemic Load: An Effort by the PREVIEW Consortium

Dietary glycaemic index (GI) and glycaemic load (GL) are indices used to quantify the effect of carbohydrate quality and quantity on postprandial glycaemia. GI/GL-health associations are widely studied but data on the validity of integrated GI/GL measurements are scarce. We evaluated the performance of a food-frequency questionnaire (FFQ) specifically developed to assess GI/GL. In total, 263 Dutch men and 212 women (aged 55 ± 11 years) completed a 58-item GI-FFQ, an 183-item general-FFQ and a 2-day 24 h-recall and donated blood for glycated haemoglobin (HbA1c) determination. The level of agreement between these methods was evaluated by (1) cross-classification, (2) correlations and (3) Bland and Altman plots. The three dietary assessment methods provided comparable mean intake estimates for total carbohydrates (range: 214–237 g/day), mono/disaccharides (100–107 g/day), polysaccharides (114–132 g/day), as well as bread, breakfast cereals, potatoes, pasta, rice, fruit, dairy, cakes/cookies and sweets. Mean (±SD) GI estimates were also comparable between the GI-FFQ (54 ± 3), general-FFQ (53 ± 4) and 24 h-recalls (53 ± 5). Mean (±SD) GI-FFQ GL (117 ± 37) was slightly lower than the general-FFQ GL (126 ± 38) and 24 h-recalls GL (127 ± 37). Classification of GI in quartiles was identical for the GI-FFQ and general-FFQ for 43% of the population (r = 0.58) and with 24 h-recalls for 35% of the population (de-attenuated r = 0.64). For GL, this was 48% (r = 0.65) and 44% (de-attenuated r = 0.74). Correlations between GI and HbA1c were low (r = −0.09 for GI-FFQ, r = −0.04 for general-FFQ and r = 0.07 for 24 h-recalls). In conclusion, compared to a general-FFQ and 24 h-recalls, the GI-FFQ showed a moderate to good relative validity for carbohydrates, carbohydrate-rich foods and GI/GL. No metric predicted HbA1c.

Low 10-year reproducibility of glycaemic index and glycaemic load in a prospective cohort study

When relating glycaemic index (GI) and glycaemic load (GL) to health outcomes, many prospective cohort studies assess the nutritional exposure only once in time, that is, at the start of the study, presuming a stability in nutritional consumption during the course of the study. The aim of this study is to investigate the reproducibility of GI and GL. This is a prospective cohort study in which 562 middle-aged Belgian adults noted all foods and drinks consumed during 3 d in 2002 and 2012. GI and GL were calculated after reference tables. The Pearson correlation coefficients between 2002 and 2012 were 0·27 for GI and 0·41 for GL. For GI, 33 % of the participants remained in the same quintile between 2002 and 2012, whereas 31 % moved to a non-adjacent quintile. For GL, this was 34 and 28 %, respectively. The lowest and the highest quintiles of GI were the most stable, with 40 and 44 % of the participants staying in the same quintile. This was only 22 % for the fourth quintile. The same tendency was present for GL – that is, the most extreme quintiles were the most stable. This study shows 10-year correlation coefficients for GI and GL below 0·50. Multiple nutritional assessments and limiting the analysis to the extreme quintiles of GI and GL will limit a possible misclassification in the prospective cohort studies owing to the low reproducibility.

Dietary carbohydrate intake, glycaemic load, glycaemic index and ovarian cancer risk in African-American women

Epidemiological evidence regarding the association between carbohydrate intake, glycaemic load (GL) and glycaemic index (GI) and risk of ovarian cancer has been mixed. Little is known about their impact on ovarian cancer risk in African-American women. Associations between carbohydrate quantity and quality and ovarian cancer risk were investigated among 406 cases and 609 controls using data from the African American Cancer Epidemiology Study (AACES). AACES is an ongoing population-based case-control study of ovarian cancer in African-Americans in the USA. Cases were identified through rapid case ascertainment and age- and site-matched controls were identified by random-digit dialling. Dietary information over the year preceding diagnosis or the reference date was obtained using a FFQ. Multivariable logistic regression models were used to estimate odds ratios and 95% CI adjusted for covariates. The OR comparing the highest quartile of total carbohydrate intake and total sugar intake v. the lowest quartile were 1·57 (95% CI 1·08, 2·28; P trend=0·03) and 1·61 (95% CI 1·12, 2·30; P trend<0·01), respectively. A suggestion of an inverse association was found for fibre intake. Higher GL was positively associated with the risk of ovarian cancer (OR 1·18 for each 10 units/4184 kJ (1000 kcal); 95% CI 1·04, 1·33). No associations were observed for starch or GI. Our findings suggest that high intake of total sugars and GL are associated with greater risk of ovarian cancer in African-American women.

Development and Applicability of an Internet-Based Diet and Lifestyle Questionnaire for College Students in China: A Cross-Sectional Study

Diet contributes to the increasing incidence of chronic diseases. Thus, fast, accurate, and convenient dietary assessment tools are in demand. We designed an internet-based diet and lifestyle questionnaire for Chinese (IDQC). The objective of this study was to validate its applicability and assess the dietary habits of Chinese college students.Six hundred forty-four college students from northern China were recruited and asked to complete the IDQC for the last 4 months (135 food items) and 3-day diet records (3DDRs). Food and nutrient intakes recorded in the IDQC were validated against those in the 3DDRs using the Wilcoxon matched-pairs t test, correlation analysis, and cross-classification. The Student t and χ tests were used in the dietary assessment.There were significantly positive correlations in the dietary intakes of 9 food groups and 23 nutrients between the IDQC and 3DDRs. All participants consumed low levels of fruits, vegetables, legumes, dairy, and certain micronutrients (ie, vitamin A, vitamin B1, vitamin B2, folic acid, vitamin C, calcium, selenium, and iodine), and high levels of iron and manganese. Male students consumed higher intakes of the food groups and nutrients than female students.The IDQC represents an accurate and convenient dietary assessment tool that can be used in large populations. Inadequate and excessive nutrition co-existed in college students, and more fruits, vegetables, legumes, dairy, and various vitamins and minerals were needed in this population's daily diet. The IDQC is free of access at www.yyjy365.org/diet.

High dietary glycemic load is associated with increased risk of colon cancer

High dietary glycemic load (GL) has been inconsistently associated with risk of colon cancer. We analyzed data for 1093 incident cases and 1589 controls in a population-based case-control study of colon cancer to further clarify the GL-colon cancer relationship. GL was assessed using a self-administered food frequency questionnaire. Cases had a significantly higher GL intake (mean = 136.4, SD = 24.5) than controls (mean = 132.8, SD = 25.2) (P = 0.0003). In a multivariate unconditional logistic regression model, the odds ratios (ORs) for colon cancer increased significantly with increasing GL: compared to the bottom quartile of GL, the ORs (95% CI) for the 2nd through the upper quartiles were 1.38 (1.06, 1.80), 1.67 (1.30, 2.13), and 1.61 (1.25, 2.07), respectively (P trend < 0.0001). Stratified analyses showed that the association was more pronounced among older participants [ORs (95% CI) for the 2nd through the upper quartiles were 1.35 (0.91, 2.00), 1.87 (1.29, 2.71), 2.02 (1.39, 2.95), respectively] than among younger participants [ORs were 1.46 (1.02, 2.10), 1.53 (1.09, 2.15), and 1.35 (0.96, 1.91), respectively] (P int = 0.02). Our results provide support for the hypothesis that a diet with high GL increases the risk of colon cancer.

Development, relative validity, and reliability of a food frequency questionnaire for a case-control study on dietary advanced glycation end products and diabetes complications

Dietary advanced glycation end products (dAGEs) could be involved on diabetes complications, yet their quantification is not standardized. The objective of this study was to design a food frequency questionnaire (FFQ) for dAGEs, and to assess its reliability and validity. For the design, data from 30 subjects was used. The final instrument had 90 food items. To measure reliability and validity, 20 participants with type 2 diabetes filled out twice the FFQ (FFQ-T1, FFQ-T2) and 7-day food records (7-dFR). The Shrout-Fleiss coefficient was 0.98 showing good reliability. For validation, the results for the weighted kappa were 0.55 (moderate agreement) for FFQ-T1 and 0.64 (good agreement) for FFQ-T2, and 75% and 80% of subjects respectively were correctly classified into tertiles; Bland-Altman graphics showed no systematic bias. This FFQ is comparable to 7-dFR for measuring dAGEs. To our knowledge, this is the first questionnaire designed to measure specifically dAGEs.

Validity and reliability of a dish-based, semi-quantitative food frequency questionnaire for Korean diet and cancer research

This study evaluated the validity and reliability of applying a newly developed dish-based, semi-quantitative food frequency questionnaire (FFQ) for Korean diet and cancer research. The subjects in the present study were 288 Korean adults over 30 years of age who had completed two FFQs and four 3-day diet records (DRs) from May 2008 to February 2009. Student's t-tests, Chi-square tests, and Spearman's rank correlation coefficients were used to estimate and compare intakes from different dietary assessment tools. Agreement in quintiles was calculated to validate agreement between the results of the second FFQ (FFQ-2) conducted in February 2009 and the DRs. Median Spearman's correlation coefficients between the intake of nutrients and foods assessed by the FFQ-1 and FFQ-2 were 0.59 and 0.57, respectively, and the coefficients between the intake of nutrients and foods assessed by the FFQ-2 and the DRs were 0.31 and 0.29, respectively. The quintile classifications of same or adjacent quintile for intake of nutrients and foods were 64% and 65%, respectively. Misclassification into opposite quintiles occurred in less than 5% for all dietary factors. Thus this newly-developed, Korean dish-based FFQ demonstrated moderate correspondence with the four 3-day DRs. Its reliability and validity are comparable to those reported in other studies.

Dietary fiber, carbohydrate quality and quantity, and mortality risk of individuals with diabetes mellitus

BACKGROUND

Dietary fiber, carbohydrate quality and quantity are associated with mortality risk in the general population. Whether this is also the case among diabetes patients is unknown.

OBJECTIVE

To assess the associations of dietary fiber, glycemic load, glycemic index, carbohydrate, sugar, and starch intake with mortality risk in individuals with diabetes.

METHODS

This study was a prospective cohort study among 6,192 individuals with confirmed diabetes mellitus (mean age of 57.4 years, and median diabetes duration of 4.4 years at baseline) from the European Prospective Investigation into Cancer and Nutrition (EPIC). Dietary intake was assessed at baseline (1992-2000) with validated dietary questionnaires. Cox proportional hazards analysis was performed to estimate hazard ratios (HRs) for all-cause and cardiovascular mortality, while adjusting for CVD-related, diabetes-related, and nutritional factors.

RESULTS

During a median follow-up of 9.2 y, 791 deaths were recorded, 306 due to CVD. Dietary fiber was inversely associated with all-cause mortality risk (adjusted HR per SD increase, 0.83 [95% CI, 0.75-0.91]) and CVD mortality risk (0.76[0.64-0.89]). No significant associations were observed for glycemic load, glycemic index, carbohydrate, sugar, or starch. Glycemic load (1.42[1.07-1.88]), carbohydrate (1.67[1.18-2.37]) and sugar intake (1.53[1.12-2.09]) were associated with an increased total mortality risk among normal weight individuals (BMI≤25 kg/m(2); 22% of study population) but not among overweight individuals (P interaction≤0.04). These associations became stronger after exclusion of energy misreporters.

CONCLUSIONS

High fiber intake was associated with a decreased mortality risk. High glycemic load, carbohydrate and sugar intake were associated with an increased mortality risk in normal weight individuals with diabetes.

Stability of the Framingham Nutritional Risk Score and its component nutrients over 8 years: the Framingham Nutrition Studies

BACKGROUND/OBJECTIVES

Diet quality indices are increasingly used in nutrition epidemiology as dietary exposures in relation to health outcomes. However, literature on the long-term stability of these indices is limited. We aimed to assess the stability of the validated Framingham Nutritional Risk Score (FNRS) and its component nutrients over 8 years, as well as the validity of the follow-up FNRS.

SUBJECTS/METHODS

Framingham Offspring/Spouse Study women and men (n=1734) aged 22-76 years were evaluated over 8 years. Individuals' nutrient intake and nutritional risk scores were assessed using 3-day dietary records administered at baseline (1984-1988) and at follow-up (1992-1996). Agreement between baseline and follow-up FNRS and nutrient intakes was evaluated by Bland-Altman method; stability was assessed using intra-class correlation (ICC) and weighted Kappa statistics. The effect of diet quality (as assessed by the FNRS) on cardiometabolic risk factors was evaluated using analysis of covariance.

RESULTS

Modest changes from baseline (15%) were observed in nutrient intake. The stability coefficients for the FNRS (ICC: women, 0.49; men, 0.46; P<0.0001) and many nutrients (ICC 0.3) were moderate. Over half of the women and men (58%) remained in the same or contiguous baseline and follow-up quartile of the FNRS and few (3-4%) shifted >1 quartile. The FNRS was directly associated with body mass index in women (P<0.01) and high-density lipoprotein cholesterol among both women (P<0.001) and men (P<0.01).

CONCLUSIONS

The FNRS and its constituent nutrients remained relatively stable over 8 years of follow-up. The stability of diet quality has implications for prospective epidemiological investigations.

Dietary glycemic load and glycemic index and risk of coronary heart disease and stroke in Dutch men and women: the EPIC-MORGEN study

BACKGROUND

The associations of glycemic load (GL) and glycemic index (GI) with the risk of cardiovascular diseases (CVD) are not well-established, particularly in men, and may be modified by gender.

OBJECTIVE

To assess whether high dietary GL and GI increase the risk of CVD in men and women.

METHODS

A large prospective cohort study (EPIC-MORGEN) was conducted within the general Dutch population among 8,855 men and 10,753 women, aged 21-64 years at baseline (1993-1997) and free of diabetes and CVD. Dietary intake was assessed with a validated food-frequency questionnaire and GI and GL were calculated using Foster-Powell's international table of GI. Information on morbidity and mortality was obtained through linkage with national registries. Cox proportional hazards analysis was performed to estimate hazard ratios (HRs) for incident coronary heart disease (CHD) and stroke, while adjusting for age, CVD risk factors, and dietary factors.

RESULTS

During a mean follow-up of 11.9 years, 581 CHD cases and 120 stroke cases occurred among men, and 300 CHD cases and 109 stroke cases occurred among women. In men, GL was associated with an increased CHD risk (adjusted HR per SD increase, 1.17 [95% CI, 1.02-1.35]), while no significant association was found in women (1.09 [0.89-1.33]). GI was not associated with CHD risk in both genders, while it was associated with increased stroke risk in men (1.27 [1.02-1.58]) but not in women (0.96 [0.75-1.22]). Similarly, total carbohydrate intake and starch intake were associated with a higher CHD risk in men (1.23 [1.04-1.46]; and 1.24 [1.07-1.45]), but not in women.

CONCLUSION

Among men, high GL and GI, and high carbohydrate and starch intake, were associated with increased risk of CVD.

Relative validity of a FFQ in measuring carbohydrate fractions, dietary glycaemic index and load: exploring the effects of subject characteristics

FFQ require validation as part of epidemiological research of diet–disease relationships. Studies exploring associations between carbohydrate type and chronic diseases are rapidly increasing, but information on the validity of carbohydrate fractions, dietary glycaemic index (GI) and the glycaemic load (GL) estimated by FFQ is scarce. Likewise, the effects of subject characteristics on FFQ validity have been poorly documented. The present study evaluates the relative validity of an 131-item FFQ in relation to two 3 d food records (FR) performed 6 months apart focusing on the intake of carbohydrate fractions, dietary GI and the GL. Furthermore, we assessed the extent to which subjects' age, education and BMI explain differences between these methods. The study sample comprised 218 men and 292 women aged 25–74 years participating in a large population-based survey in Finland. Energy-adjusted Spearman's rank correlations ranged from 0·27 (sugars) to 0·70 (lactose) for men and from 0·37 (sugars) to 0·69 (lactose) for women. On average, 73 % of the subjects were categorised into the same or adjacent distribution quintile based on the two methods. In general, the FFQ overestimated the intakes compared with FR. Especially in women, FFQ validity for some nutrients was associated with the level of intake, subjects' age and, to a lesser extent, education but not BMI. In conclusion, the FFQ appears to be reasonably valid in the assessment of carbohydrate exposure variables, but the findings show a need for adjustment of diet–disease relationships for subjects' age and education.

Glycemic index and glycemic load and their association with C-reactive protein and incident type 2 diabetes

Objective. To investigate whether the Glycemic Index (GI) or Glycemic Load (GL) of a diet is associated with C-reactive Protein (CRP) and risk of type 2 diabetes in a prospective study. Materials and Methods. Our analysis included 4,366 participants who did not have diabetes at baseline. During follow-up 456 diabetes cases were confirmed. Dietary GI and GL were derived from a food-frequency questionnaire and its association with CRP was examined cross-sectionally using linear regression models. The association of GI and GL with diabetes incidence was examined using Cox proportional hazard models. Results. GL, but not GI, was associated with lnCRP at baseline (b_GL = 0.11 per 50 units; P = .01). When comparing the highest to the lowest tertile of GI with respect to diabetes incidence, a Relative Risk (RR) of 0.95 [95%CI 0.75, 1.21] was found after adjustment for lifestyle and nutritional factors. For GL the RR for diabetes incidence was 1.00 [95%CI 0.74, 1.36]. Additional adjustment for CRP did not change RRs. Conclusion. Since GI was not associated with CRP and risk of type 2 diabetes, it is unlikely that a high GI diet induces the previously shown positive association between CRP and risk of type 2 diabetes by increasing CRP concentrations.

Carbohydrate quantity and quality and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) study

BACKGROUND

Carbohydrate quantity and quality may play an important role in the development of type 2 diabetes.

OBJECTIVE

We investigated the associations of dietary glycemic load (GL), glycemic index (GI), carbohydrate, and fiber intake with the incidence of type 2 diabetes.

DESIGN

A prospective cohort study was conducted in 37,846 participants of the EPIC-NL (European Prospective Investigation into Cancer and Nutrition-Netherlands) study, aged 21-70 y at baseline and free of diabetes. Dietary intake was assessed with the use of a validated food-frequency questionnaire. Incident diabetes cases were mainly self-reported and verified against general practitioner records.

RESULTS

During a mean follow-up of 10 y, 915 incident diabetes cases were documented. Dietary GL was associated with an increased diabetes risk after adjustment for age, sex, established diabetes risk factors, and dietary factors [hazard ratio (HR) per SD increase: 1.27; 95% CI: 1.11, 1.44; P < 0.001] [corrected]. GI tended to increase diabetes risk (HR: 1.08; 95% CI: 1.00, 1.17; P = 0.05). Dietary fiber was inversely associated with diabetes risk (HR: 0.92; 95% CI: 0.85, 0.99; P < 0.05), whereas carbohydrate intake was associated with increased diabetes risk (HR: 1.15; 95% CI: 1.01, 1.32; P < 0.05). Of the carbohydrate subtypes, only starch was related to increased diabetes risk [HR: 1.25 (1.07, 1.46), P < 0.05]. All associations became slightly stronger after exclusion of energy misreporters.

CONCLUSIONS

Diets high in GL, GI, and starch and low in fiber were associated with an increased diabetes risk. Both carbohydrate quantity and quality seem to be important factors in diabetes prevention. Energy misreporting contributed to a slight attenuation of associations.