Methodology for adding glycemic index and glycemic load values to 24-hour dietary recall database

Development of a national database for dietary glycemic index and load for nutritional epidemiologic studies in the United States

BACKGROUND

The quality of carbohydrate intake, as measured by the glycemic index (GI), has not been evaluated nationally over the past 2 decades in the United States.

OBJECTIVES

We aimed to develop a comprehensive and nationally representative dietary GI and glycemic load (GL) database from 1999 to 2018 National Health and Nutrition Examination Survey (NHANES) and to examine GI and GL time trends and subpopulation differences.

METHODS

We used an artificial intelligence (AI)-enabled model to match GI values from 2 GI databases to food codes from United States Department of Agriculture, which were manually validated. We examined nationally representative distributions of dietary GI and GL from 1999 to 2018 using the multistage, clustered sampling design of NHANES.

RESULTS

Assigned GI values covered 99.9% of total carbohydrate intake. The initial AI accuracy was 75.0%, with 31.3% retained after manual curation guided by substantive domain expertise. A total of 7976 unique food codes were matched to GI values, of which soft drinks and white bread were top contributors to dietary GI and GL. Of the 49,205 NHANES adult participants, the mean dietary GI was 55.7 (95% confidence interval [CI]: 55.5, 55.8) and energy-adjusted dietary GL was 133.0 (95% CI: 132.3, 133.8). From 1999 to 2018, dietary GI and GL decreased by 4.6% and 13.8%, respectively. Dietary GL was higher among females (134.6; 95% CI: 133.8, 135.5) than among males (131.3; 95% CI: 130.3, 132.3), those with ≤high school degree (137.7; 95% CI: 136.8, 138.7) than among those with ≥college degree (126.5; 95% CI: 125.3, 127.7), and those living under the poverty level (140.9; 95% CI: 139.6, 142.1) than among those above the poverty level. Differences in race were observed (Black adults, 139.4; 95% CI: 138.2, 140.7; White adults, 131.6; 95% CI: 130.5, 132.6).

CONCLUSIONS

The national GI and GL database facilitates large-scale and high-quality surveillance or cohort studies of diet and health outcomes in the United States.

Plasma metabolomic response to high-carbohydrate meals of differing glycaemic load in overweight women

BACKGROUND

Metabolomic dysregulation following a meal in overweight individuals with the Metabolic Syndrome (MetS) involves multiple pathways of nutrient storage and oxidation.

OBJECTIVE

The aim of the current study was to perform an acute cross-over intervention to examine the interactive actions of meal glycaemic load (GL) on the dynamic responses of the plasma metabolome in overweight females.

METHODS

Postmenopausal women [63 ± 1.23y; Healthy (n = 20) and MetS (n = 20)] ingested two differing high-carbohydrate test meals (73 g carbohydrate; 51% energy) composed of either low glycemic index (LGI) or high (HGI) foods in a randomised sequence. Plasma metabolome was analysed using liquid chromatography-mass spectrometry (LC-MS).

RESULTS

In the overweight women with MetS, there were suppressed postprandial responses for several amino acids (AAs), including phenylalanine, leucine, valine, and tryptophan, p < 0.05), irrespective of the meal type. Meal GL exerted a limited impact on the overall metabolomic response, although the postprandial levels of alanine were higher with the low GL meal and uric acid was greater following the high GL meal (p < 0.05).

CONCLUSIONS

MetS participants exhibited reduced differences in the concentrations of a small set of AAs and a limited group of metabolites implicated in energy metabolism following the meals. However, the manipulation of meal GL had minimal impact on the postprandial metabolome. This study suggests that the GL of a meal is not a major determinant of postprandial response, with a greater impact exerted by the metabolic health of the individual. Trial registration Australia New Zealand Clinical Trials Registry: ACTRN12615001108505 (21/10/2015).

Has new rural pension system reduced the intake of junk food among rural older adults? Evidence from China

At present, China has become one of the fastest growing countries in terms of junk food consumption. However, there has been less previous evidence for the effect of endowment insurance on dietary health. Using the data China Family Panel Studies (CFPS) from 2014, this paper exploits a policy, the New Rural Pension System (NRPS), that only the older adults who have reached 60 years old can receive pensions and conduct a fuzzy regression discontinuity (FRD) to address endogeneity and examine the causal effect of the NRPS on the intake of junk food among rural older adults in China. We find that the NRPS can significantly reduce junk food intake among them, which remains robust after a series of robustness tests. In addition, heterogeneity analysis shows that the female, low-educated, unemployed, and low-income groups are more sensitive to the pension shock from the NRPS. The result of our study provides insights to effectively improve people's dietary quality and related policy formulation.

Dietary Glycemic Index and Glycemic Load Are Not Associated with the Metabolic Syndrome in Lebanese Healthy Adults: A Cross-Sectional Study

High dietary glycemic index (GI) and glycemic load (GL) were suggested to increase the risk of metabolic syndrome (MetS). This study aims to estimate dietary GI and GL in a sample of healthy Lebanese adults and examine their association with MetS and its individual abnormalities. The study uses data from a community-based survey of 501 Lebanese urban adults. Dietary intake was assessed using a food frequency questionnaire. Biochemical, anthropometric, and blood pressure measurements were obtained. Subjects with previous diagnosis of chronic disease, metabolic abnormalities, or with incomplete data or implausible energy intakes were excluded, yielding a sample of 283. Participants were grouped into quartiles of GI and GL. Multivariate logistic regression analyses were performed. Average dietary GI and GL were estimated at 59.9 ± 8 and 209.7 ± 100.3. Participants belonging to the highest GI quartile were at increased risk of having MetS (odds ratio (OR) = 2.251, 95% CI:1.120–4.525) but this association lost significance with further adjustments. Those belonging to the second quartile of GI had significantly lower odds of having hyperglycemia (OR: 0.380, 95% CI:0.174–0.833). No associations were detected between GL and MetS. The study contributes to the body of evidence discussing the relationship between GI, GL, and MetS, in a nutrition transition context.

Association between Dietary Glycaemic Index and Glycaemic Load and Adiposity Indices in Polycystic Ovary Syndrome

Objective: Obesity is a key contributor to metabolic and reproductive outcomes in polycystic ovary syndrome (PCOS). The role of the dietary glycemic index (GI) and load (GL), and adiposity has been debated and studies on PCOS are scarce. We aimed to compare the dietary GI and GL and several anthropometric measurements in PCOS and control women. The association between dietary GI and GL and adiposity indices was examined in this cross-sectional study.Methods and materials: A study population consisted of 65 previously diagnosed with PCOS and 65 healthy women. All participants underwent detailed anthropometric, dietary and physical activity evaluation and categorized based on GI and GL tertiles.Results: When dietary GL was adjusted for age, physical activity level (PAL), and duration of diagnosis, there was a statistically significant inverse association between dietary GL and waist/hip ratio (WHR) (OR: 0.136; 95% CI: 0.021-0.874; p = 0.036) in women with PCOS. Both dietary GI (OR: 8.869; 95% CI: 1.194-65.910; p = 0.033 for tertile 2 in adjustment model) and GL (OR: 7.200; 95% CI: 1.635-31.712; p = 0.009 for tertile 3 in crude model; OR: 5.801; 95% CI: 1.242-27.096; p = 0.025 for tertile 3 in adjustment model) positively associated with WHR in healthy subjects. Also, positive association was observed between dietary GI and waist/height ratio (WHtR) (OR: 0.229; 95% CI: 0.063-0.826; p = 0.024 for tertile 2; OR: 0.277; 95% CI: 0.078-0.988; p = 0.048 for tertile 3) in healthy controls, however after adjustment for age and PAL, statistical significance was lost (OR: 1.051; 95% CI: 0.152-7.261; p = 0.959 for tertile 2; OR: 1.522; 95% CI: 0.225-10.297; p = 0.667 for tertile 3).Conclusion: The results of this study consistent with the literature that PCOS is associated with increased adiposity indices. There was no association between dietary GI/GL and BMI, WC, WHtR, and ABSI but dietary GL was inversely associated WHR in PCOS patients.

Effects of dietary glycemic index and load on children's cardiovascular risk factors

PURPOSE

Consumption of foods high in glycemic index (GI) and glycemic load (GL) is associated with cardiovascular (CV) diseases in adulthood. We examined whether GI and GL predict CV risk factors in children after 2 years of follow-up.

METHODS

Three 24-hour recalls were administered at baseline, and individual average daily GI and GL scores were calculated in a cohort of 8-10 year-old children. CV risk factors included body mass index z-score (BMIz), percent fat mass, triglycerides (TGs), low-density lipoprotein and high-density lipoprotein (HDL) cholesterol, and systolic and diastolic blood pressure. Main analyses consisted of multiple linear regression adjusted for anthropometric, socioeconomic, and dietary factors.

RESULTS

After 2 years, the highest dietary GL tertile compared with the lowest was associated with increased BMIz (mean difference [MD], 1.1; 95% CI, 0.88-1.31), fat mass (MD, 10.8%; 95% CI, 8.62-13.0), TGs (MD, 0.17 mmol/L; 95% CI, 0.07-0.28), and decreased HDL (MD, -0.13 mmol/L; 95% CI, -0.19 to -0.07). The GL-TG and the GL-HDL associations were mediated by BMIz.

CONCLUSIONS

GL predicts increased BMIz, percent fat mass, and TGs and decreased HDL in young children after 2 years. Recommendations to decrease CV risk in children should include lowering foods high in GL.

Healthy Eating and Active Living for Diabetes-Glycemic Index (HEALD-GI): Protocol for a Pragmatic Randomized Controlled Trial

BACKGROUND

Rigorous evidence is needed regarding the best approach for increasing the uptake of Diabetes Canada's evidence-based recommendations to include low-glycemic index (GI) foods in daily meal planning as an effective dietary self-care strategy for glycemic control among people with type 2 diabetes (T2D).

OBJECTIVE

This study aims to present the study design and baseline data from the Healthy Eating and Active Living for Diabetes-Glycemic Index (HEALD-GI) trial, which was designed to evaluate the effectiveness of an enhanced GI-targeted nutrition education on GI-related knowledge and mean daily GI among adults with T2D in Edmonton, Alberta.

METHODS

We used a pragmatic randomized controlled trial design and allocated 67 adults (aged ≥18 years) with T2D living in Edmonton, Alberta, Canada, to a control group that received standard printed copies of Canada's Food Guide and Diabetes Canada's GI resources or to an intervention group that received the same materials, plus a customized Web-based platform with 6 self-directed learning modules and print material. Each module included videos, links to reliable websites, chat rooms, and quizzes. Evidence-based GI concept information included GI values of foods and low-GI shopping, recipes, and cooking tips by a registered dietitian. In addition, support through email, text messaging (short message service), phone calls, or postal mail was provided to reinforce participants' learning. The primary outcome, average dietary GI, was assessed using 3-day food records. Additional measures including GI knowledge and self-efficacy, glycated hemoglobin (HbA_1c), lipids, systolic blood pressure, body mass index (BMI; weight, height), waist circumference, and computer proficiency were assessed at baseline and at 3-month postintervention.

RESULTS

Between November 2017 and February 2018, we contacted adults (aged ≥18 years) with T2D living in Edmonton, Alberta, screened and recruited eligible participants into the study. All data collection ended in June 2018. Overall, 64% (43/67) participants were males; mean age was 69.5 (SD 9.3) years, with a mean diabetes duration of 19.0 (SD 13.7) years. Mean BMI was 30.1 (SD 5.7) kg/m², and mean HbA_1c value was 7.1% (SD 1.2%). Data analysis was completed in December 2018.

CONCLUSIONS

The GI concept is often difficult to teach. The HEALD-GI study aims to provide evidence in support of an alternative approach to translating the GI concept to adults with T2D. Findings from this study may help registered dietitians to better disseminate low-GI dietary recommendations using efficient and cost-effective, patient-centered approaches. Furthermore, evidence generated will contribute to addressing some of the controversies regarding the clinical usefulness of the GI concept.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/11707.

Examining sex differences in glycemic index knowledge and intake among individuals with type 2 diabetes

AIM

We examined self-reported dietary behaviours and actual food intakes among adult men and women with type 2 diabetes participating in Alberta's Caring for Diabetes (ABCD) Study.

METHODS

Participants completed 3-day food records and questions about glycemic index (GI) concept knowledge and dietary behaviours. Daily average GI and glycemic load (GL) were calculated for all carbohydrates consumed. Dietary intake was analyzed using ESHA FoodPro (version 10.13.1). Sex differences in nutrient intakes were explored across categories of GI knowledge and dietary practices.

RESULTS

Participants (N=170) mean (SD) age 65.8 (9.6) years were 46.5% women, 90.6% Caucasian with a mean BMI of 31.3 (7.0)kg/m² and diabetes duration of 13.4 (8.6) years. Overall, 60% of men versus 40% of women consumed carbohydrates in quantities below Acceptable Macronutrient Distribution Ranges (AMDR). About 80% of men versus 90% of women consumed proteins above AMDR whereas 60% versus 65% of women consumed fats above AMDR. Fibre intake among men was lower than recommended (p<0.01). Men who reported having knowledge of the GI-concept also reported lower GI intake versus men who did not (p=0.03).

CONCLUSION

Sex differences exist in low-GI diabetes self-care dietary behaviours among adults with type 2 diabetes participating in this study. Gender-sensitive approaches for enhancing diabetes self-care low-GI dietary behaviour should be explored.

Greater diet quality is associated with more optimal glycemic control in a longitudinal study of youth with type 1 diabetes

BACKGROUND

Despite the centrality of nutrition in the management of type 1 diabetes, the association of diet quality and macronutrient distribution with glycemic control is ambiguous.

OBJECTIVE

This study examined longitudinally the association of dietary intake with multiple indicators of glycemic control in youth with type 1 diabetes participating in a behavioral nutrition intervention study.

DESIGN

Participants in a randomized clinical trial of a behavioral nutrition intervention [n = 136; mean ± SD age: 12.8 ± 2.6 y; glycated hemoglobin (HbA1c): 8.1% ± 1.0%; 69.1% using an insulin pump] completed 3-d diet records at baseline and months 3, 6, 9, 12, and 18; masked continuous glucose monitoring (CGM) data were obtained concurrently with the use of the Medtronic iPro CGM system. HbA1c was obtained every 3 mo; 1,5-anhydroglucitol was obtained every 6 mo. Linear mixed-effects regression models estimated associations of time-varying dietary intake variables with time-varying glycemic control indicators, controlling for age, height, weight, sex, Tanner stage, diabetes duration, regimen, frequency of blood glucose monitoring, physical activity, and treatment assignment.

RESULTS

HbA1c was associated inversely with carbohydrate and natural sugar, and positively with protein and unsaturated fat. 1,5-Anhydroglucitol was associated positively with fiber intake and natural sugar. Greater glycemic control as indicated by ≥1 CGM variable was associated with higher Healthy Eating Index-2005, whole plant food density, fiber, carbohydrate, and natural sugar and lower glycemic index and unsaturated fat.

CONCLUSIONS

Both overall diet quality and macronutrient distribution were associated with more optimal glycemic control. Associations were more consistent for CGM variables obtained concurrently with dietary intake than for biomarkers of longer-term glycemic control. These findings suggest that glycemic control may be improved by increasing intake of high-fiber, low glycemic-index, carbohydrate-containing foods. This trial was registered at clinicaltrials.gov as NCT00999375.

Methodology for adding glycemic index to the National Health and Nutrition Examination Survey nutrient database

Generating valid estimates of dietary glycemic index (GI) and glycemic load (GL) has been a challenge in nutritional epidemiology. The methodologic issues may have contributed to the wide variation of GI/GL associations with health outcomes observed in existing literature. We describe a standardized methodology for assigning GI values to items in the National Health and Nutrition Examination Survey (NHANES) nutrient database using the new International Tables to develop research-driven, systematic procedures and strategies to estimate dietary GI/GL exposures of a nationally representative population sample. Nutrient databases for NHANES 2003-2006 contain information on 3,155 unique foods derived from the US Department of Agriculture National Nutrient Database for Standard Reference versions 18 and 20. Assignment of GI values were made to a subset of 2,078 carbohydrate-containing foods using systematic food item matching procedures applied to 2008 international GI tables and online data sources. Matching protocols indicated that 45.4% of foods had identical matches with existing data sources, 31.9% had similar matches, 2.5% derived GI values calculated with the formula for combination foods, 13.6% were assigned a default GI value based on low carbohydrate content, and 6.7% of GI values were based on data extrapolation. Most GI values were derived from international sources; 36.1% were from North American product information. To confirm data assignments, dietary GI and GL intakes of the NHANES 2003-2006 adult participants were estimated from two 24-hour recalls and compared with published studies. Among the 3,689 men and 4,112 women studied, mean dietary GI was 56.2 (men 56.9, women 55.5), mean dietary GL was 138.1 (men 162.1, women 116.4); the distribution of dietary GI was approximately normal. Estimates of population GI and GL compare favorably with other published literature. This methodology of adding GI values to an existing population nutrient database utilized systematic matching protocols and the latest comprehensive data sources on food composition. The database can be applied in clinical and survey research settings where there is interest in estimating individual and population dietary exposures and relating them to health outcomes.

Glycaemic index values in the Finnish food composition database: an approach to standardised value documentation

BACKGROUND/OBJECTIVES

The glycaemic index (GI) is used to describe the blood glucose-raising potential of carbohydrate-containing foods. Only a few descriptions of the addition of GI values to national food composition databases (FCDBs) exist. We tested whether the value documentation framework established within the European Food Information Resource (EuroFIR) Network could be used for GI values when adding them to the Finnish FCDB.

METHODS

The list of foods requiring GI values was based on the National FINDIET 2007 Survey data and extended with foods encoded in a food-frequency questionnaire used in other nationally representative studies. The minimum quality of GI measurements was verified when gathering values from various sources, using earlier defined criteria. If a measured GI value for a food was directly available, or could be imputed or estimated, the value was added to the Finnish FCDB and documented using core standard vocabularies of EuroFIR. The GI values of composite foods were calculated using recipe calculation software.

RESULTS

A total of 2210 foods required a GI value. GI values for 1322 foods were available and added to the FCDB. The remaining 888 foods were composite foods and received a GI value through recipe calculation. The standard vocabularies describing the origin of the GI values, the methods used in their derivation and their qualitative characteristics were suitable for GI values.

CONCLUSIONS

GI values can be added to FCDBs and documented using terms similar to those used for traditional food composition data. Standardised value documentation may provide transparency for GI database compilation processes.

Methodology for adding and amending glycaemic index values to a nutrition analysis package

Since its introduction in 1981, the glycaemic index (GI) has been a useful tool for classifying the glycaemic effects of carbohydrate foods. Consumption of a low-GI diet has been associated with a reduced risk of developing CVD, diabetes mellitus and certain cancers. WISP (Tinuviel Software, Llanfechell, Anglesey, UK) is a nutrition software package used for the analysis of food intake records and 24 h recalls. Within its database, WISP contains the GI values of foods based on the International Tables 2002. The aim of the present study is to describe in detail a methodology for adding and amending GI values to the WISP database in a clinical or research setting, using data from the updated International Tables 2008.

A randomized behavioural trial targeting glycaemic index improves dietary, weight and metabolic outcomes in patients with type 2 diabetes

Objective

Glycaemic index (GI) reflects the postprandial glucose response of carbohydrate-containing foods. A diet with lower GI may improve glycaemic control in people with diabetes. The purpose of the present study was to evaluate the change in outcomes following a behavioural intervention which promoted lower-GI foods among adults with diabetes.

Design

A pre-test–post-test control group design was used with participants randomly assigned to an immediate (experimental) or delayed (control) treatment group. The intervention included a 9-week, group-based intervention about carbohydrate and the glycaemic index. Dietary, anthropometric and metabolic measures were obtained pre/post-intervention in both groups and at 18-week follow-up for the immediate group.

Setting

The study was conducted in a rural community in the north-eastern USA.

Subjects

Adults having type 2 diabetes mellitus for ≥1 year, aged 40–70 years and not requiring insulin therapy (n 109) were recruited.

Results

Following the intervention, mean dietary GI (P < 0·001), percentage of energy from total fat (P < 0·01) and total dietary fibre (P < 0·01) improved in the immediate compared with the delayed group. Mean BMI (P < 0·0001), fasting plasma glucose (P = 0·03), postprandial glucose (P = 0·02), fructosamine (P = 0·02) and insulin sensitivity factor (P = 0·04) also improved in the immediate group compared with the delayed group. Mean waist circumference among males (P < 0·01) and body weight among males and females (P < 0·01) were significantly different between treatment groups.

Conclusions

Educating clients about carbohydrate and the glycaemic index can improve dietary intake and health outcomes among adults with type 2 diabetes.

Marcador in vitro da resposta glicêmica dos alimentos como ferramenta de auxílio à prescrição e avaliação de dietas

As dietas de baixo índice glicêmico e baixa carga glicêmica têm sido associadas à redução do risco de doenças crônicas. Por esse motivo há um interesse crescente na sua aplicação para avaliação e orientação nutricional. No entanto, existem limitações quanto ao uso de dados publicados de índice glicêmico e carga glicêmica, pela variedade e formas de processamento dos alimentos vegetais existentes. Devido à dificuldade de realização de ensaios in vivo, uma vez que são custosos, trabalhosos, invasivos e necessitam de período considerável de experimentação, foram desenvolvidas metodologias in vitro que, a partir da velocidade de digestão dos carboidratos, permitem estimar o índice glicêmico dos alimentos de forma prática, simples e econômica. O presente trabalho apresenta o uso de um marcador in vitro, o índice de hidrólise, na estimativa do índice glicêmico e da carga glicêmica, o método mais empregado por pesquisadores brasileiros, visando à sua aplicação por profissionais da área de Nutrição. Os cálculos e as interpretações para estimativa do Índice glicêmico e da carga glicêmica são apresentados por meio de um exemplo prático com alguns alimentos brasileiros e com o grão de amaranto submetido a diferentes processamentos. Na ausência de dados referentes à resposta glicêmica do alimento de interesse, os valores do marcador in vitro podem ser utilizados para estimar o índice glicêmico e a carga glicêmica dos alimentos. Porém, este marcador não deve ser utilizado indiscriminadamente, uma vez que leva em consideração apenas os fatores intrínsecos aos alimentos que influenciam o aproveitamento dos carboidratos disponíveis.

Self-monitoring predicts change in fiber intake and weight loss in adults with diabetes following an intervention regarding the glycemic index

OBJECTIVE

Self-monitoring can facilitate behavioral change by providing feedback regarding goal attainment. Glycemic index (GI) quantifies the glycemic response to carbohydrate-containing foods. Low GI diets may improve weight and glycemic control. We examined the relation between self-monitoring and changes in diet and body weight following an intervention in which consumption of low GI foods was encouraged among adults aged 40-70 years with diabetes.

METHODS

Pre/post-intervention dietary intake was assessed with 24-h dietary recalls and weight was obtained. Mean number of days participants kept self-monitoring records was determined. The impact of self-monitoring on the change in GI, fiber intake, weight and body mass index (BMI) was evaluated using regression analyses.

RESULTS

Each additional day of self-monitoring was associated with a mean reduction in weight and BMI of -0.95 kg and -0.34 kg/m(2), respectively. The mean change in fiber intake increased in men but did not significantly change in women for each additional day of monitoring.

CONCLUSION

Self-monitoring was associated with weight loss in men and women and greater fiber intake in men.

PRACTICE IMPLICATIONS

Men can self-monitor to lose weight and increase fiber intake. Self-monitoring facilitates weight loss in women but other behavioral strategies are needed to improve fiber intake.

Change in food choices following a glycemic load intervention in adults with type 2 diabetes

The glycemic index (GI) reflects the postprandial glucose response of carbohydrate-containing foods, and adoption of a lower-GI diet may be beneficial in diabetes management. The purpose of this study was to evaluate change in food-group intake by participants after completing an intervention that included instruction about carbohydrate and the GI using a quasi-experimental design. Recruitment occurred from February to August 2005 and September to December 2006. Individuals 40 to 70 years old with type 2 diabetes for 1 year or longer were randomly assigned to an immediate (n=55) or delayed (n=48) treatment group. A 9-week group-based intervention regarding the quantity and type of carbohydrate for diabetes management was provided. Three sets of 24-hour dietary recalls were used to assess food-group intake. Foods were divided into nine main food groups and 166 subgroups based on the Dietary Guidelines for Americans 2005 and the United States Department of Agriculture's Food Guide Pyramid. Analysis of variance was used to examine between-group differences and paired t test compared maintenance of change for the immediate group. Change in dietary GI was significantly different between groups upon completion of the intervention by the immediate group (P<0.05). Participants consumed significantly more servings of whole fruit and nonfat dairy products following the intervention and fewer servings of vegetable fats (all P<0.05). Only whole-fruit consumption significantly declined in the immediate group during the maintenance period (P<0.05). Nutrition education can facilitate adoption of a lower-GI diet among free-living people with diabetes. Maintaining dietary change likely requires further intervention and support.

Methodological challenges in the application of the glycemic index in epidemiological studies using data from the European Prospective Investigation into Cancer and Nutrition

Associations between the glycemic index (GI) or glycemic load (GL) and diseases are heterogeneous in epidemiological studies. Differences in assigning GI values to food items may contribute to this inconsistency. Our objective was to address methodological issues related to the use of current GI and GL values in epidemiological studies. We performed ecological comparison and correlation studies by calculating dietary GI and GL from country-specific dietary questionnaires (DQ) from 422,837 participants from 9 countries participating in the European Prospective Investigation into Cancer and Nutrition study and single standardized 24-h dietary recalls (24-HDR) obtained from a representative sample (n = 33,404) using mainly Foster Powell's international table as a reference source. Further, 2 inter-rater and 1 inter-method comparison were conducted, comparing DQ GI values assigned by independent groups with values linked by us. The ecological correlation between DQ and 24-HDR was good for GL (overall r = 0.76; P < 0.005) and moderate for GI (r = 0.57; P < 0.05). Mean GI/GL differences between DQ and 24-HDR were significant for most centers. GL but not GI from DQ was highly correlated with total carbohydrate (r = 0.98 and 0.15, respectively; P < 0.0001) and this was higher for starch (r = 0.72; P < 0.0001) than for sugars (r = 0.36; P < 0.0001). The inter-rater and inter-method variations were considerable for GI (weighted kappa coefficients of 0.49 and 0.65 for inter-rater and 0.25 for inter-method variation, respectively) but only mild for GL (weighted kappa coefficients > 0.80). A more consistent methodology to attribute GI values to foods and validated DQ is needed to derive meaningful GI/GL estimates for nutritional epidemiology.

Índice glicêmico: uma abordagem crítica acerca de sua utilização na prevenção e no tratamento de fatores de risco cardiovasculares

As doenças cardiovasculares são consideradas um grande problema de saúde pública, uma vez que são a principal causa de morte no Brasil e no mundo. Essas doenças possuem etiologia multifatorial. Além da susceptibilidade genética, outros fatores, tais como idade e presença de hipertensão arterial, dislipidemias, obesidade, diabetes mellitus, inatividade física e alguns hábitos alimentares inadequados, são considerados importantes fatores de risco para o desenvolvimento de doenças cardiovasculares. O elevado consumo de carboidratos tem sido associado ao aumento da obesidade, às dislipidemias, à intolerância à glicose/diabetes mellitus e à resistência insulínica, estando, dessa forma, entre os fatores de risco das doenças cardiovasculares. Entretanto, existem controvérsias acerca da influência da qualidade do carboidrato ingerido no desenvolvimento de tais doenças, independentemente da quantidade ingerida. O índice glicêmico é um indicador da qualidade do carboidrato ingerido. Sua utilidade em condições de vida livre tem sido questionada, devido à interferência de vários fatores, os quais são difíceis de serem controlados sob tais condições. Este trabalho objetivou analisar criticamente os estudos que avaliaram o efeito do índice glicêmico dos alimentos na manifestação de doenças cardiovasculares e seus fatores de risco.

Association between dietary glycemic index, glycemic load, and high-sensitivity C-reactive protein

OBJECTIVE

This study examined the relation between quality of dietary carbohydrate intake, as measured by glycemic index (GI) and glycemic load (GL), and serum high-sensitivity C-reactive protein (hs-CRP) levels.

METHODS

During a 1-y observational study, data were collected at baseline and at each quarter thereafter. GI and GL were calculated from multiple 24-h dietary recalls (24HRs), 3 randomly selected 24HRs at every quarter, with up to 15 24HRs per participant. The hs-CRP was measured in blood samples collected at baseline and each of the four quarterly measurement points. Multivariable linear mixed models were used to examine the cross-sectional and longitudinal associations of GI, GL, and hs-CRP.

RESULTS

Among 582 adult men and women with at least two measurements of diet and hs-CRP, average daily GI score (white bread = 100) was 85 and average GL was 198, and average hs-CRP was 1.84 mg/L. Overall, there was no association between GI or GL and hs-CRP. Subgroup analyses revealed an inverse association between GL and hs-CRP among obese individuals (body mass index > or =30 kg/m(2)).

CONCLUSION

Quality of dietary carbohydrates does not appear to be associated with serum hs-CRP levels. Among obese individuals, higher dietary GL appears to be related to lower hs-CRP levels. Due to the limited number of studies on this topic and their conflicting results, further investigation is warranted.