Glycemic load, glycemic index and risk of cardiovascular diseases: Meta-analyses of prospective studies

Dietary inflammation and vascular calcification: a comprehensive review of the associations, underlying mechanisms, and prevention strategies

Cardiovascular disease (CVD) is one of the leading causes of death globally, and vascular calcification (VC) has been recognized as an independent and strong predictor of global CVD and mortality. Chronic inflammation has been demonstrated to play a significant role in the progression of VC. This review aims to summarize the literature that aimed to elucidate the associations between dietary inflammation (DI) and VC as well as to explore the mechanisms underlying the association and discuss strategies (including dietary interventions) to prevent VC. Notably, diets rich in processed foods, carbohydrates with high glycemic index/load, saturated fatty acids, trans-fatty acids, cholesterol, and phosphorus were found to induce inflammatory responses and accelerate the progression of VC, indicating a close relationship between DI and VC. Moreover, we demonstrate that an imbalance in the composition of the gut microbiota caused by the intake of specific dietary choices favored the production of certain metabolites that may contribute to the progression of VC. The release of inflammatory and adhesion cytokines, activation of inflammatory pathways, oxidative stress, and metabolic disorders were noted to be the main mechanisms through which DI induced VC. To reduce and slow the progression of VC, emphasis should be placed on the intake of diets rich in omega-3 fatty acids, dietary fiber, Mg, Zn, and polyphenols, as well as the adjustment of dietary pattern to reduce the risk of VC. This review is expected to be useful for guiding future research on the interplay between DI and VC.

The Portfolio Diet and HbA1c in Adults Living with Type 2 Diabetes Mellitus: A Patient-Level Pooled Analysis of Two Randomized Dietary Trials

(1) Background: The Portfolio Diet, a dietary pattern of cholesterol-lowering foods, is also rich in low glycemic index (GI) foods. While strong evidence supports clinically meaningful reductions in cholesterol, evidence on the relationship between the Portfolio Diet and diabetes management is lacking. (2) Objective: To evaluate the relationship between the Portfolio Diet and glycated hemoglobin (HbA1c) as a determinant of glycemic control among adults living with type 2 diabetes mellitus (T2DM). (3) Methods: Patient-level data was pooled from two randomized dietary trials of low glycemic index interventions compared to high cereal fibre control diets in adults living with T2DM where HbA1c was collected (clinicaltrials.gov identifiers: NCT00438698, NCT00438698). Dietary exposure was assessed using weighed 7-day diet records. Adherence to the Portfolio Diet and its pillars (nuts and seeds, plant protein, viscous fibre, plant sterols, monounsaturated fatty acid [MUFA] oils) was determined using the validated clinical Portfolio Diet Score (c-PDS). Multiple linear regression was used to assess the association between change in the c-PDS and change in HbA1c over 6-months with covariate adjustments. (4) Results: A total of 267 participants, predominantly White (67%) and male (63%), were included, with a mean ± standard error age of 62 ± 0.5 years, baseline BMI of 30.2 ± 0.3 kg/m2, HbA1c of 7.08 ± 0.03%, and a c-PDS of 4.1 ± 0.3 points out of 25. Change in the c-PDS was significantly associated with a change in HbA1c (β: -0.04% per point, 95% CI: -0.07, -0.02, p = 0.001). A 7.5-point (30%) increase in the c-PDS was associated with a 0.3% reduction in HbA1c. Of the individual pillars, a 1-point change in nut and seeds intake (β: -0.07%, 95% CI: -0.12, -0.02, p = 0.009) or in plant protein intake (β: -0.11%, 95% CI: -0.18, -0.03, p = 0.009) was associated with a change in HbA1c. Further analysis of plant protein intake revealed that an increase in dietary pulse intake, a particularly low-GI food, was significantly associated with a reduction in HbA1c (β: -0.24% per 1-cup points cooked pulses (226 g) or 2 c-PDS points, 95% CI: -0.45, -0.03, p = 0.028). (5) Conclusions: Among adults living with T2DM, the Portfolio Diet was associated with lower HbA1c over a 6-month period, predominantly driven by two pillars: nuts and seeds and plant protein, particularly dietary pulses. These data have implications for including the Portfolio Diet in dietary recommendations for glycemic control in T2DM. A trial demonstrating the direct causal effect of the Portfolio Diet in a diverse group is warranted.

Cognition of diet quality and dietary management in elderly patients with coronary and other atherosclerotic vascular disease in western China, a qualitative research study

BACKGROUND

Healthy eating is one of the most important nonpharmacologic treatments for patients with atherosclerosis(AS). However, it is unclear how elderly AS patients in western China perceive their dietary status and which type of nutritional assistance they would be willing to receive. Therefore, the primary purpose of this study was to understand the level of knowledge about current dietary habits and healthy eating habits among elderly AS patients in western China, and the secondary purpose was to identify acceptable nutritional assistance measures or pathways for those patients to help them manage disease progression.

METHODS

An implementation study approach was used to recruit elderly patients with AS-related diseases in western China for semistructured interviews.

RESULTS

14 participants were included in the study, and the following three themes were identified from the interviews:(1) the diet with regional characteristics; (2) low nutrition-related health literacy; (3) complex attitudes towards nutritional assistance. Most participants had misconceptions about healthy eating, and the sources of their knowledge might not be trustworthy. Participants expressed a preference for personalized nutritional assistance, especially that provided by medical-nursing combined institutions.

CONCLUSION

Patients in western China need nutritional assistance for their regional dietary habits; therefore, healthy dietary patterns consistent with the regional culture are proposed to improve the prevailing lack of knowledge about healthy diets, improve the dietary structure of patients, and control the development of the disease.

Effects on cardiovascular risk factors of a low- vs high-glycemic index Mediterranean diet in high cardiometabolic risk individuals: the MEDGI-Carb study

BACKGROUND

The role of dietary Glycemic Index (GI), independently of fiber intake, in modulating cardiovascular disease (CVD) risk among non-diabetic individuals has not been fully elucidated.

OBJECTIVE

To evaluate the effects of a low- versus a high-GI diet, based on a Mediterranean dietary pattern, on cardiometabolic risk factors in individuals at high CVD risk, participating in the MEDGI-Carb intervention study.

SUBJECTS AND METHODS

160 individuals, aged 30-69 years, BMI 25-37 kg/m2, with a waist circumference >102 cm (males) or >88 cm (females) and one feature of the metabolic syndrome, participated in a multi-national (Italy, Sweden, USA) randomized controlled parallel group trial. Participants were assigned to a low GI (< 55) or high-GI MedDiet ( > 70) for 12 weeks. The diets were isoenergetic and similar for available carbohydrate (270 g/d) and fiber (35 g/d) content. Fasting metabolic parameters were evaluated in the whole cohort, while an 8-h triglyceride profile (after standard breakfast and lunch) was evaluated only in the Italian cohort.

RESULTS

Blood pressure and most fasting metabolic parameters improved at the end of the dietary intervention (time effect, p < 0.05 for all); however, no differences were observed between the low- and the high-GI MedDiet groups (time x group effect; p > 0.05 for all). Conversely, the low-GI diet, compared with high-GI diet, significantly reduced the 8-h triglyceride profile (p < 0.017, time*group effect) that was measured only in the Italian cohort. However, it induced a reduction of plasma triglycerides after lunch (tAUC) that was of only borderline statistically significance (p = 0.065).

CONCLUSIONS

Consuming a low-GI in comparison with a high-GI MedDiet does not differentially affect the major cardiometabolic risk factors at fasting in individuals at increased cardiometabolic risk. Conversely, it could reduce postprandial plasma triglycerides.

CLINICAL TRIAL REGISTRY NUMBER

NCT03410719, ( https://clinicaltrials.gov ).

The association between glycemic index, glycemic load and total carbohydrate intake and risk of premature coronary artery disease: Iran Premature Coronary Artery Disease Study (IPAD) - A Case-Control Study

BACKGROUND AND AIMS

The association between glycemic index (GI), glycemic load (GL), total carbohydrate intake, and risk of cardiovascular diseases has been controversial. Premature coronary artery disease (PCAD) is characterized by the age of onset lower than 55 and 65 respectively in men and women. The aim of the current study is to investigate the relationship between GI, GL and carbohydrate levels and the risk of PCAD in Iran.

METHODS AND RESULTS

In total, 419 healthy people and 553 patients struggling with PCAD have participated in this case-control study. Dietary GI and GL were calculated using a validated food frequency questionnaire at the baseline. Crude and multivariable logistic regression were used to assess the relationship between GI, GL, and total carbohydrate intake and risk of PCAD. The mean age of participants was 51.13 ± 6.90 and 46 % of them were women. A significant direct relationship was observed between higher carbohydrate intake (OR: 1.74, 95%CI: 1.27-2.38) and GL levels (OR: 1.56, 95 % CI:1.14-2.14) and risk of PCAD. These associations were not significant after adjusting for potential variables. No significant association has been observed between GI and odds of PCAD even after controlling for all covariates.

CONCLUSION

We found no significant association between GI, GL, and total carbohydrate intake and risk of premature coronary heart disease. Further observational and clinical trials are required to assess this relationship.

Endosperm structure and Glycemic Index of Japonica Italian rice varieties

Introduction

Given that rice serves as a crucial staple food for a significant portion of the global population and with the increasing number of individuals being diagnosed with diabetes, a primary objective in genetic improvement is to identify and cultivate low Glycemic Index (GI) varieties. This must be done while ensuring the preservation of grain quality.

Methods

25 Italian rice genotypes were characterized calculating their GI "in vivo" and, together with other 29 Italian and non-Italian genotypes they were studied to evaluate the grain inner structure through Field Emission Scanning Electron Microscopy (FESEM) technique. Using an ad-hoc developed algorithm, morphological features were extracted from the FESEM images, to be then inspected by means of multivariate data analysis methods.

Results and Discussion

Large variability was observed in GI values (49 to 92 with respect to glucose), as well as in endosperm morphological features. According to the percentage of porosity is possible to distinguish approximately among rice varieties having a crystalline grain (< 1.7%), those intended for the preparation of risotto (> 5%), and a third group having intermediate characteristics. Waxy rice varieties were not united by a certain porosity level, but they shared a low starch granules eccentricity. With reference to morphological features, rice varieties with low GI (<55) seem to be characterized by large starch granules and low porosity values. Our data testify the wide variability of Italian rice cultivation giving interesting information for future breeding programs, finding that the structure of the endosperm can be regarded as a specific characteristic of each variety.

Refined grain intake and cardiovascular disease: Meta-analyses of prospective cohort studies

Refined grains are included as part of an unhealthy, or Western, dietary pattern, which has been shown to be associated with increased risk of cardiovascular disease (CVD). To clarify the association between refined grain intake and CVD risk, Pubmed and Scopus databases were searched for relevant cohort studies from database inception to June 30, 2022. Only studies that examined refined grains as a distinct consumption category and not as part of a dietary pattern, were included. Meta-analyses were performed using Cochrane's RevMan 5.4.1 software, applying inverse variance risk ratios in random effects models for each outcome of interest. Heterogeneity was assessed with Cochrane's Q (chi2) and I2 statistics. Meta-analyses of hazard ratios (HR) and 95% confidence intervals (CI) obtained from 17 prospective cohort studies (>875,000 participants) indicated that refined grain intake was not associated with risk of CVD (HR = 1.08, 95% CI, 0.99-1.18, I2 = 70%; 9 cohorts), stroke (HR = 1.06, 95% CI 0.92-1.23, I2 = 70%; 9 cohorts), or heart failure (HR = 0.95, 95% CI 0.77-1.16, I2 = 10%; 5 cohorts). White rice intake was also not associated with risk of CVD (HR = 0.93, 95% CI 0.86-1.00, I2 = 25%; 7 cohorts) or stroke (HR = 1.03, 95% CI 0.93-1.14, I2 = 22%; 7 cohorts). No significant publication bias was evident (Egger's test P values all > 0.05). The lack of association between refined grain intake and CVD risk was observed in meta-analyses of studies that restricted analyses to only staple grain foods (e.g., bread, cereal, pasta, white rice), as well as for meta-analyses of studies that included both staple and indulgent grain foods (e.g., cakes, cookies, doughnuts, brownies, muffins, pastries). Probable confounding from unmeasured variables in studies included in the meta-analyses diminishes the overall quality of evidence. Although refined grains are included as a component of the Western dietary pattern, the results of the meta-analyses suggest that refined grains do not contribute to the higher CVD risk associated with this unhealthy dietary pattern. This information should be considered in formulation of future dietary recommendations.

Changes in dietary carbohydrate and lipid quality indices between 2008 and 2018: Analysis of the Brazilian dietary surveys

The aim of the study was to evaluate characteristics and changes over a decade in dietary carbohydrate and lipid quality according to socio-demographic variables. Data was obtained from two Brazilian National Dietary Surveys 2008-2009 (n = 34 003) and 2017-2018 (n = 46 164) examining a nationwide representative sample of individuals ≥10 years old. Food intake was assessed by means of two non-consecutive diet records (2008-2009) and 24 h diet recalls (2017-2018). Carbohydrate Quality Index is a score ranging from 4 to 20 calculated from fibre intake, global dietary glycaemic index, solid/total carbohydrate (CHO) and whole grains/total grains CHO. Lipid Quality Index was estimated by dividing the sum of the dietary content of monounsaturated and polyunsaturated fatty acids by the sum of saturated and trans fatty acids. Indices were categorised into five categories (1 for lowest and 5 for highest quality). Socio-demographic variables were sex, age, income, urban/rural area and place of food consumption. The estimates (95% CI) were generated separately for each survey and then compared to identify changes in time. Our main findings refer to changes in diet quality according to income. At the lowest income level, the proportions of individuals in the best carbohydrate and lipid quality categories reduced from 26.9% to 20.6% and from 30.0% to 24.9%, respectively. Alternatively, at the highest income level, these proportions increased from 22.9% to 26.6% and from 11.9% to 15.7%, respectively. Furthermore, the quality of lipids improved in women and among individuals reporting some away-from-home food consumption, while the quality of carbohydrates was reduced among adolescents and in rural areas.

Physicochemical, Antioxidant, Sensory, and Starch Digestibility Properties of Steamed Bread Fortified with Tamarillo Powder

The effects of lyophilized tamarillo powder (TP) on the physicochemical, antioxidant, sensory, and starch digestibility characteristics of steamed breads were studied. The TP was used to substitute 5-20% of wheat flour to make steamed breads, assigned as T5, T10, T15, and T20, respectively. The results showed that TP is rich in dietary fiber (36.45%). Its extract is rich in bioactive components, including phenolic compounds (28.90 mg GAE/g extract), ascorbic acid (3.25 mg/g extract), total anthocyanins (316.35 μg C3GE/g extract), and total carotenoids (12.68 μg βCE/g extract) and has good antioxidant capacity. As the level of TP increased, the color of steamed breads became darker, redder, and yellower; the texture became harder, and the overall consumption preference decreased. However, their bioactive components content and antioxidant activity increased. The starch hydrolysis percentage of T5 (43.82%), T10 (41.57%), T15 (37.41%), and T20 (35.63%) at 180 min was significantly lower than that of the control (49.80%) (p < 0.05). The in vitro predicted glycemic index (80.02) of T20 was categorized as a medium-GI food when bread was used as the reference. On a nine-point hedonic test, control and T5 had the highest overall preference scores (7.1-7.4). The T20 supplemented with extra 15-20% water improved its volume and specific volume, and the overall preference scores (7.4-7.5) were not significantly different from the control (p > 0.05). Overall, a partial replacement of wheat flour with TP in steamed bread making could be developed as a new type of medium-GI value food containing more bioactive components and effective antioxidant capacity.

Relation of dietary insulin index and dietary insulin load to metabolic syndrome depending on the lifestyle factors: Tehran lipid and glucose study

AIM

The hypothesis of the effect of the insulinogenic effects of diet on the development of cardiovascular diseases has been proposed, but the findings of previous studies are very contradictory. We investigated the association between dietary insulin index (DII) and dietary insulin load (DIL), and metabolic syndrome (MetS) risk. Another objective was to examine the extent to which lifestyle (physical activity, smoking status, and weight change) and sex influence the relationship between DII, DIL, and MetS risk.

MATERIALS AND METHODS

We followed 1915 participants in the Tehran Lipid and Glucose Study. DIL and DII were calculated based on a validated food frequency questionnaire. Weight change was measured, and participants were categorized into > 3% weight loss, weight stable (± 3%), and > 3% weight gain. By joint classification, the association between DII and DIL (< median and ≥ median) and risk of MetS was assessed according to weight change, sex, physical activity levels, and smoking status. Cox proportional hazards models were used to estimate the HRs (95% CI), adjusting for potential confounders.

RESULTS

During 8.9 years of follow-up, among 1915 participants, we documented 591 new cases of MetS. DII and DIL were not associated with MetS risk in the crude and adjusted models. However, DIL and DII were associated with weight gain (≥ 3%). In the crude model, DIL and DII were associated with a higher risk of weight gain [HR: 1.74: 95% CI 1.50-2.03, and 1.70 (1.46-1.98), respectively]. These associations remained significant after further adjustment for confounders. The HRs were 1.61 (1.35-1.92) for DIL and 1.64 (1.39-1.93) for DII. Among men, women, participants with low physical activity levels, and smokers, the risk of MetS, independent of DIL and DII, only increased in a participant with weight gain. In women with weight stability, DIL and DII, higher than the median, were positively associated with MetS risk.

CONCLUSION

Our findings suggest that the association between MetS risk and a hyperinsulinemic diet depended on weight change.

The association between dietary glycemic index and cardio-metabolic risk factors in obese individuals

Background:

The dietary glycemic index (GI) has been introduced as a novel index to elucidate the potential of foods to increase postprandial glucose. According to the limited available data about the association of GI with cardio-metabolic risk factors such as lipid profile, blood glucose markers, and blood pressure in developing countries, the current study was conducted to investigate this association in apparently obese individuals.

Method and material:

Three hundred forty-seven obese adults were recruited in the present cross-sectional study. A validated 147-food item semi-quantitative food frequency questionnaire (FFQ) was used to evaluate the usual dietary intake of study participants. Dietary GI was calculated using the international GI database. Fatty acid desaturase (FADs)2 gene variants were determined according to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). ANOVA was used to compare study variables across different tertile of GI.

Results:

We found significant differences in terms of anthropometric parameters [weight (P = 0.038), waist circumference (WC) (P = 0.023), weight to hip ratio (WHR) (P = 0.007), and fat-free mass (FFM) (P < 0.001)] between different tertiles of GI. Similarly, energy and macronutrient intakes had a significant difference across dietary GI, and subjects with a higher dietary intake of energy and macronutrients (carbohydrate, protein, and total fat) were assigned to the third tertile of dietary GI (P < 0.001). While there was no significant difference in terms of cardio-metabolic risk factors in different dietary GI tertiles. Moreover, the total GI score was non-significantly higher in the TT genotype of FADS2 gene polymorphism compared with other genotypes. While no significant difference was observed between FADS2 genotype frequencies in different GI tertiles.

Conclusion:

Calculated dietary GI was associated with several cardio-metabolic risk factors in obese individuals. However, further prospective studies and clinical trials are needed to confirm our findings.

Comparative study of physicochemical, nutritional, phytochemical, and sensory properties of bread with plantain and soy flours partly replacing wheat flour

Plantain flour (PLF) and soy flour (SF) were used to substitute wheat flour (10% and 20% w/w) in composite bread. Physicochemical, phytochemical, and sensory properties were investigated. Partial substitution by PLF significantly increased (p < .05) starch, amylose, ascorbic acid, and potassium content in bread samples. In contrast, a significant improvement (p < .05) in protein, fat, amylopectin, and calcium content was observed with SF substitution. Composite bread with PLF and SF together lowered the hydrolysis index (HI) and glycemic index (GI) as compared with whole wheat flour. The molar phytate to minerals (iron, zinc, and calcium) ratio in all composite loaves was lower than reported critical values, except for phytate to iron. Significant differences (p < .05) were found in color, specific volume, and texture characteristics of loaves made from partial substitution with PLF and SF. Sensory evaluation revealed that bread with 10% PLF exhibited better scores for appearance and willingness to pay than the control. In contrast, SF negatively affected (p < .05) the appearance, texture, color, overall acceptance, and willingness to pay. The trade-off analysis indicated that PLF can be utilized to produce bread that meets consumers' demands, while incorporating SF as an alternative high-nutrient density bread will be beneficial to health.

The dietary and lifestyle indices of insulin resistance are associated with increased risk of cardiovascular diseases: A prospective study among an Iranian adult population

BACKGROUND AND AIMS

Previous studies have introduced insulin resistance (IR) as a major risk factor for poor cardiovascular diseases (CVDs) outcomes. Diet, body weight, and physical activity are three key pillars of lifestyle that can significantly impact the IR status. We aimed to assess the possible link between the empirical dietary index for IR (EDIR) and the empirical lifestyle index for IR (ELIR) with the risk of chronic heart disease (CHD) and CVDs.

METHODS AND RESULTS

This study was conducted on 4980 participants aged ≥30 years (follow-up rate: 99.85%). Dietary intake data was collected using a validated food frequency questionnaire. Cox proportional hazard regression was used to estimate the hazard ratio and 95% confidence intervals (HRs and 95% CIs) of CVDs and CHD across tertiles of EDIR and ELIR scores. In the final model, after adjusting for all potential confounding variables, participants in the highest tertile of EDIR had a higher risk of CVD (HR:1.36, 95%CI:1.03-1.80, P-trend = 0.016) and CHD (HR:1.36, 95% CI:1.01-1.83, P-trend = 0.023) compared to the lowest tertile. Also, participants with a higher score of ELIR had a higher risk of CVD (HR: 1.64, 95%CI:1.24-2.16, P-trend=<0.001) and CHD (HR: 1.72, 95%CI:1.28-2.32, P-trend=<0.001).

CONCLUSION

A greater adherence to the lifestyle and diet with a higher EDIR and ELIR may be associated with an increased risk of CVD and CHD outcomes in the adult population.

Acute Effects of Split Pea-Enriched White Pan Bread on Postprandial Glycemic and Satiety Responses in Healthy Volunteers—A Randomized Crossover Trial

Pulse consumption has been associated with reduced postprandial glucose response (PPGR) and improved satiety. The objective of this study was (i) to investigate the effects of fortifying white pan bread with split yellow pea (Pisum sativum L.) flour on PPGR and appetite-related sensations, and (ii) to determine whether Revtech heat processing of pea flour alters the postprandial effects. A randomized controlled crossover trial was performed with 24 healthy adults. Participants consumed 50 g available carbohydrate from bread containing 20% pea flour that was untreated (USYP), Revtech processed at 140 °C with no steam (RT0%), Revtech processed at 140 °C with 10% steam (RT10%), or a control bread with 100% white wheat flour (100%W). Blood samples were analyzed for glucose and plasma insulin at 0, 15, 30, 45, 60, 90, and 120 min post-meal. Appetite sensations and product acceptability were measured using visual analogue and 9-point hedonic scales. Results showed no significant difference in the postprandial glucose and insulin responses of different bread treatments. However, pea-containing variants resulted in 18% higher fullness and 16–18% lower hunger, desire to eat, and prospective food consumption ratings compared to 100% W. No differences in the aroma, flavor, color, and overall acceptability of different bread products were observed. This trial supports using pea flour as a value-added ingredient to improve the short-term appetite-related sensations of white pan bread without affecting the overall acceptability.

Associations of Glycemic Index and Glycemic Load with Cardiovascular Disease: Updated Evidence from Meta-analysis and Cohort Studies

PURPOSE OF REVIEW

Diet and lifestyle patterns are considered major contributory factors for cardiovascular disease (CVD) and mortality. In particular, consuming a diet higher in carbohydrates (not inclusive of fruits and vegetables, but more processed carbohydrates) has been associated with metabolic abnormalities that subsequently may increase the risk of CVD and related mortality. Glycemic index (GI) and glycemic load (GL) are values given to foods based on how fast the body converts carbohydrates into glucose also referred to as the glycemic burden of carbohydrates from foods. Conflicting associations of how high GI and GL influence CVDs have been observed even in high-quality meta-analysis studies. We synthesize and report the associations of high GI and GL with various CVDs by sex, obesity, and geographical locations using an updated review of meta-analysis and observational studies.

RECENT FINDINGS

We identified high GI or high GL is associated with an increased risk of CVD events including diabetes (DM), metabolic syndrome (MS), coronary heart disease (CHD), stroke, and stroke mortality in the general population, and the risk of CVD outcomes appears to be stratified by sex, obesity status, and preexisting CVD. Both high GI and GL are associated with DM and CHD in the general population. However, high GI is strongly associated with DM/MS, while high GL is strongly associated with an increased risk of CHD in females. In addition, high GL is also associated with incident stroke, and appears to be associated with CVD mortality in subjects with preexisting CVD or high BMI and all-cause mortality in non-obese DM subjects. However, high GI appears to be associated with CVD or all-cause mortality only in females without CVD. High GI/GL is an important risk factor for CVD outcomes in the general population. High GI seems to be markedly associated with DM/MS, and it may enhance the risk of CVD or all-cause mortality in both sexes and predominately females. Although both high GI and high GL are risk factors for CHD in females, high GL is associated with CVD outcomes in at-risk populations for CVD. These data suggest that while high GI increases the propensity of CVD risk factors and mortality in healthy individuals, high GL contributes to the risk of severe heart diseases including CVD or all-cause mortality, particularly in at-risk populations. These data indicate dietary interventions designed for focusing carbohydrate quality by lowering both GI and GL are recommended for preventing CVD outcomes across all populations.

Precision Nutrition Model Predicts Glucose Control of Overweight Females Following the Consumption of Potatoes High in Resistant Starch

Individual glycemic responses following dietary intake result from complex physiological processes, and can be influenced by physical properties of foods, such as increased resistant starch (RS) from starch retrogradation. Predictive equations are needed to provide personalized dietary recommendations to reduce chronic disease development. Therefore, a precision nutrition model predicting the postprandial glucose response (PPGR) in overweight women following the consumption of potatoes was formulated. Thirty overweight women participated in this randomized crossover trial. Participants consumed 250 g of hot (9.2 g RS) or cold (13.7 g RS) potatoes on two separate occasions. Baseline characteristics included demographics, 10-day dietary records, body composition, and the relative abundance (RA) and α-diversity of gut microbiota. Elastic net regression using 5-fold cross-validation predicted PPGR after potato intake. Most participants (70%) had a favorable PPGR to the cold potato. The model explained 32.2% of the variance in PPGR with the equation: 547.65 × (0 [if cold, high-RS potato], ×1, if hot, low-RS potato]) + (BMI [kg/m²] × 40.66)—(insoluble fiber [g] × 49.35) + (Bacteroides [RA] × 8.69)—(Faecalibacterium [RA] × 73.49)—(Parabacteroides [RA] × 42.08) + (α-diversity × 110.87) + 292.52. This model improves the understanding of baseline characteristics that explain interpersonal variation in PPGR following potato intake and offers a tool to optimize dietary recommendations for a commonly consumed food.

Nutrients and Dietary Approaches in Patients with Type 2 Diabetes Mellitus and Cardiovascular Disease: A Narrative Review

Cardiovascular disease (CVD) is the most common cause of morbidity and mortality in developed countries. The prevalence of CVD is much higher in patients with type 2 diabetes mellitus (T2DM), who may benefit from lifestyle changes, which include adapted diets. In this review, we provide the role of different groups of nutrients in patients with T2DM and CVD, as well as dietary approaches that have been associated with better and worse outcomes in those patients. Many different diets and supplements have proved to be beneficial in T2DM and CVD, but further studies, guidelines, and dietary recommendations are particularly required for patients with both diseases.

Perspective: Does Glycemic Index Matter for Weight Loss and Obesity Prevention? Examination of the Evidence on "Fast" Compared with "Slow" Carbs

High-glycemic index (high-GI) foods (so-called fast carbs) have been hypothesized to promote fat storage and increase risk of obesity. To clarify whether dietary GI impacts body weight, we searched PubMed and the Cochrane Database of Systematic Reviews for observational studies reporting associations between BMI and dietary GI, and for meta-analyses of randomized controlled trials (RCTs) comparing low-GI and high-GI diets for weight loss. Data on 43 cohorts from 34 publications, totaling 1,940,968 adults, revealed no consistent differences in BMI when comparing the highest with the lowest dietary GI groups. In the 27 cohort studies that reported results of statistical comparisons, 70% showed that BMI was either not different between the highest and lowest dietary GI groups (12 of 27 cohorts) or that BMI was lower in the highest dietary GI group (7 of 27 cohorts). Results of 30 meta-analyses of RCTs from 8 publications demonstrated that low-GI diets were generally no better than high-GI diets for reducing body weight or body fat. One notable exception is that low-GI diets with a dietary GI at least 20 units lower than the comparison diet resulted in greater weight loss in adults with normal glucose tolerance but not in adults with impaired glucose tolerance. While carbohydrate quality, including GI, impacts many health outcomes, GI as a measure of carbohydrate quality appears to be relatively unimportant as a determinant of BMI or diet-induced weight loss. Based on results from observational cohort studies and meta-analyses of RCTs, we conclude that there is scant scientific evidence that low-GI diets are superior to high-GI diets for weight loss and obesity prevention.

Longitudinal changes in adherence to the portfolio and DASH dietary patterns and cardiometabolic risk factors in the PREDIMED-Plus study

BACKGROUND & AIMS

The Portfolio and Dietary Approaches to Stop Hypertension (DASH) diets have been shown to lower cardiometabolic risk factors in randomized controlled trials (RCTs). However, the Portfolio diet has only been assessed in RCTs of hyperlipidemic patients. Therefore, to assess the Portfolio diet in a population with metabolic syndrome (MetS), we conducted a longitudinal analysis of one-year data of changes in the Portfolio and DASH diet scores and their association with cardiometabolic risk factors in Prevención con Dieta Mediterránea (PREDIMED)-Plus trial.

METHODS

PREDIMED-Plus is an ongoing clinical trial (Trial registration: ISRCTN89898) conducted in Spain that includes 6874 older participants (mean age 65 y, 48% women) with overweight/obesity fulfilling at least three criteria for MetS. Data for this analysis were collected at baseline, six months and one year. Adherence to the Portfolio and DASH diet scores were derived from a validated 143-item food frequency questionnaire. We used linear mixed models to examine the associations of 1-SD increase and quartile changes in the diet scores with concomitant changes in cardiometabolic risk factors.

RESULTS

After adjusting for several potential confounders, a 1-SD increase in the Portfolio diet score was significantly associated with lower HbA1c (β [95% CI]: -0.02% [-0.02, -0.01], P < 0.001), fasting glucose (-0.47 mg/dL [-0.83, -0.11], P = 0.01), triglycerides (-1.29 mg/dL [-2.31, -0.28], P = 0.01), waist circumference (WC) (-0.51 cm [-0.59, -0.43], P < 0.001), and body mass index (BMI) (-0.17 kg/m² [-0.19, -0.15], P < 0.001). A 1-SD increase in the DASH diet score was significantly associated with lower HbA1c (-0.03% [-0.04, -0.02], P < 0.001), glucose (-0.84 mg/dL [-1.18, -0.51], P < 0.001), triglycerides (-3.38 mg/dL [-4.37, -2.38], P < 0.001), non-HDL-cholesterol (-0.47 mg/dL [-0.91, -0.04], P = 0.03), WC (-0.69 cm [-0.76, -0.60 cm], P < 0.001), BMI (-0.25 kg/m² [-0.28, -0.26 kg/m²], P < 0.001), systolic blood pressure (-0.57 mmHg [-0.81, -0.32 mmHg], P < 0.001), diastolic blood pressure (-0.15 mmHg [-0.29, -0.01 mmHg], P = 0.03), and with higher HDL-cholesterol (0.21 mg/dL [0.09, 0.34 mg/dL, P = 0.001]). Similar associations were seen when both diet scores were assessed as quartiles, comparing extreme categories of adherence.

CONCLUSIONS

Among older adults at high cardiovascular risk with MetS, greater adherence to the Portfolio and DASH diets showed significant favourable prospective associations with several clinically relevant cardiometabolic risk factors. Both diets are likely beneficial for cardiometabolic risk reduction.

Low-carbohydrate diets and cardiometabolic health: the importance of carbohydrate quality over quantity

Carbohydrates are increasingly being implicated in the epidemics of obesity, diabetes, and their downstream cardiometabolic diseases. The "carbohydrate-insulin model" has been proposed to explain this role of carbohydrates. It posits that a high intake of carbohydrate induces endocrine deregulation marked by hyperinsulinemia, leading to energy partitioning with increased storage of energy in adipose tissue resulting in adaptive increases in food intake and decreases in energy expenditure. Whether all carbohydrate foods under real-world feeding conditions directly contribute to weight gain and its complications or whether this model can explain these clinical phenomena requires close inspection. The aim of this review is to assess the evidence for the role of carbohydrate quantity vs quality in cardiometabolic health. Although the clinical investigations of the "carbohydrate-insulin model" have shown the requisite decreases in insulin secretion and increases in fat oxidation, there has been a failure to achieve the expected fat loss under low-carbohydrate feeding. Systematic reviews with pairwise and network meta-analyses of the best available evidence have failed to show the superiority of low-carbohydrate diets on long-term clinical weight loss outcomes or that all sources of carbohydrate behave equally. High-carbohydrate diets that emphasize foods containing important nutrients and substances, including high-quality carbohydrate such as whole grains (especially oats and barley), pulses, or fruit; low glycemic index and load; or high fiber (especially viscous fiber sources) decrease intermediate cardiometabolic risk factors in randomized trials and are associated with weight loss and decreased incidence of diabetes, cardiovascular disease, and cardiovascular mortality in prospective cohort studies. The evidence for sugars as a marker of carbohydrate quality appears to be highly dependent on energy control (comparator) and food source (matrix), with sugar-sweetened beverages providing excess energy showing evidence of harm, and with high-quality carbohydrate food sources containing sugars such as fruit, 100% fruit juice, yogurt, and breakfast cereals showing evidence of benefit in energy-matched substitutions for refined starches (low-quality carbohydrate food sources). These data reflect the current shift in dietary guidance that allows for flexibility in the proportion of macronutrients (including carbohydrates) in the diet, with a focus on quality over quantity and dietary patterns over single nutrients.

The association between dietary glycemic index and load and risk of gestational diabetes mellitus: A prospective study

AIMS

This study aimed to investigate the association between dietary GI and GL and risk of GDM in a group of pregnant women in Iran.

METHODS

A number of 812 pregnant women were recruited in their first trimester in a prospective study. A validated 117-item semi-quantitative food frequency questionnaire was used to assess usual dietary intakes of participants at study baseline. Dietary GI and GL were calculated based on earlier publications. GDM was diagnosed based on the results of a fasting plasma glucose concentration and a 50-g, 1-h oral glucose tolerance test at 24-28 weeks of gestation. Cox proportional hazards model was used to compute relative risks (RRs) and 95% confidence intervals (CI) for GDM.

RESULTS

Mean ± SD of age and BMI of study participants was 29.4 ± 4.84 y and 25.14 ± 4.08 kg/m², respectively at study baseline. Mean ± SD of dietary GI was 58 ± 7 and that of dietary GL was 176 ± 42. Overall, 28.4% (n = 231) of study population developed GDM at weeks 24-28 of pregnancy. After adjustment for potential confounding variables, we found that women in the highest tertile of dietary GL were 43% more likely to develop GDM than those in the lowest tertile (95% CI: 1.01, 2.00; P-trend = 0.03). However, no significant association was seen between dietary GI (RR for the highest tertile compared to the lowest: 0.85; 95% CI: 0.61, 1.20; P-trend = 0.37), and risk of GDM.

CONCLUSIONS

We found that women with the highest dietary GL were at a greater risk of developing GDM during pregnancy. No significant association was seen between dietary GI and risk of GDM.

Dietary glycemic index, glycemic load, and chronic disease: an umbrella review of meta-analyses of prospective cohort studies

We aimed to present a comprehensive review of the association of dietary glycemic index (GI) and load (GL) with the risk of chronic disease. Published meta-analyses of prospective observational studies evaluating the association of dietary GI and GL with risk of chronic disease were identified by a search in PubMed and Scopus to November, 2020. Summary relative risks (SRRs) were recalculated using random-effects models. The certainty of evidence was rated by the GRADE approach. Eighteen meta-analyses of prospective cohort studies, reporting 19 SRRs for dietary GI and 17 SRRs for dietary GL were identified. There was a positive association between dietary GI and the risk of type 2 diabetes, coronary heart disease, and colorectal, breast, and bladder cancers, as well as between dietary GL and the risk of coronary heart disease, type 2 diabetes, and stroke. With regard to cancers at other sites, there was no significant association. The certainty of evidence ranged from very low to low. Although by GRADE classification no associations were rated stronger than low, they were classified as one grade higher when the NutriGrade system was used. Further research is needed to add evidence for the relation of dietary GI and GL with cancer risk.

The association between dietary glycemic and insulin indices with incidence of cardiovascular disease: Tehran lipid and glucose study

Background

The present study was conducted to investigate the association of dietary insulin index(II), insulin load(IL), glycemic index(GI), and glycemic load(GL) with the risk of cardiovascular disease(CVD).

Methods

This cohort study was conducted within the framework of the Tehran Lipid and Glucose Study on 2198 subjects, aged≥19 years old, who were followed-up for a median (IQR) 6.7 (6.1–7.1) years. Dietary GI, GL, II, and IL were calculated using a food frequency questionnaire at the baseline. Multivariate Cox proportional hazard regression models were used to estimate the risk of CVD across quartiles of dietary insulin and glycemic indices.

Results

Mean ± SD age of the subjects(44.9% men) was 38.3 ± 13.4 years. During a mean of 2406 ± 417 person-years of follow-up, 76(3.5%) new cases of the CVD were ascertained. The mean ± SD of II, IL, GI, and GL of participants were 51.7 ± 6.5, 235.8 ± 90.2, 61.9 ± 7.8, and 202.2 ± 78.1, respectively. After adjusting for the variables of age, sex, smoking, physical activity, daily energy intake, body mass index, diabetes, and hypertension, the hazard ratio (HR) of the highest quartile of dietary GL was 2.77(95%CI:1.00–7.69,P for trend:0.033) compared to the lowest one. Also, each one SD increase in the GL score was associated with a higher risk of CVD[(RR:1.46;CI:1.00–2.16),P-value = 0.047]. However, there was no significant association between the dietary GI, II, and IL and risk for CVD incidence.

Conclusions

Our results suggested that a high GL diet can increase the incidence of CVD, whereas high dietary II and IL were not associated with the risk of CVD among adults.

The Impact of Dietary Glycemic Index and Glycemic Load on Postprandial Lipid Kinetics, Dyslipidemia and Cardiovascular Risk

Many recent studies have acknowledged postprandial hypetriglyceridemia as a distinct risk factor for cardiovascular disease. This dysmetabolic state is the result of the hepatic overproduction of very low-density lipoproteins (VLDLs) and intestinal secretion of chylomicrons (CMs), which leads to highly atherogenic particles and endothelial inflammation. Postprandial lipid metabolism does not only depend on consumed fat but also on the other classes of nutrients that a meal contains. Various mechanisms through which carbohydrates exacerbate lipidemia have been identified, especially for fructose, which stimulates de novo lipogenesis. Glycemic index and glycemic load, despite their intrinsic limitations, have been used as markers of the postprandial glucose and insulin response, and their association with metabolic health and cardiovascular events has been extensively studied with contradictory results. This review aims to discuss the importance and pathogenesis of postprandial hypertriglyceridemia and its association with cardiovascular disease. Then, we describe the mechanisms through which carbohydrates influence lipidemia and, through a brief presentation of the available clinical studies on glycemic index/glycemic load, we discuss the association of these indices with atherogenic dyslipidemia and address possible concerns and implications for everyday practice.

Association of nut intake with risk factors, cardiovascular disease, and mortality in 16 countries from 5 continents: analysis from the Prospective Urban and Rural Epidemiology (PURE) study

BACKGROUND

The association of nuts with cardiovascular disease and deaths has been investigated mostly in Europe, the USA, and East Asia, with few data available from other regions of the world or from low- and middle-income countries.

OBJECTIVE

To assess the association of nuts with mortality and cardiovascular disease (CVD).

METHODS

The Prospective Urban Rural Epidemiology study is a large multinational prospective cohort study of adults aged 35-70 y from 16 low-, middle-, and high-income countries on 5 continents. Nut intake (tree nuts and ground nuts) was measured at the baseline visit, using country-specific validated FFQs. The primary outcome was a composite of mortality or major cardiovascular event [nonfatal myocardial infarction (MI), stroke, or heart failure].

RESULTS

We followed 124,329 participants (age = 50.7 y, SD = 10.2; 41.5% male) for a median of 9.5 y. We recorded 10,928 composite events [deaths (n = 8,662) or major cardiovascular events (n = 5,979)]. Higher nut intake (>120 g per wk compared with <30 g per mo) was associated with a lower risk of the primary composite outcome of mortality or major cardiovascular event [multivariate HR (mvHR): 0.88; 95% CI: 0.80, 0.96; P-trend = 0.0048]. Significant reductions in total (mvHR: 0.77; 95% CI: 0.69, 0.87; P-trend <0.0001), cardiovascular (mvHR: 0.72; 95% CI: 0.56, 0.92; P-trend = 0.048), and noncardiovascular mortality (mvHR: 0.82; 95% CI: 0.70, 0.96; P-trend = 0.0046) with a trend to reduced cancer mortality (mvHR: 0.81; 95% CI: 0.65, 1.00; P-trend = 0.081) were observed. No significant associations of nuts were seen with major CVD (mvHR: 0.91; 95% CI: 0.81, 1.02; P-trend = 0.14), stroke (mvHR: 0.98; 95% CI: 0.84, 1.14; P-trend = 0.76), or MI (mvHR: 0.86; 95% CI: 0.72, 1.04; P-trend = 0.29).

CONCLUSIONS

Higher nut intake was associated with lower mortality risk from both cardiovascular and noncardiovascular causes in low-, middle-, and high-income countries.

Glycemic Index (GI) Values for Major Sources of Dietary Carbohydrates in Iran

BACKGROUND

The glycemic index (GI) values of staple foods are not available in a standardized method in Iran.

OBJECTIVES

The aim of this study was to measure the GI values of the major carbohydrate sources in a typical Iranian diet.

METHODS

Using the international standard method, the GI values were determined for four wheat flatbreads, barley and rye bread, white and brown rice, as well as white and brown rice mixed with lentils. Twelve healthy adults were given 50 g anhydrous glucose three times (as the reference carbohydrate) and the test foods once each throughout the study. Using finger-prick blood samples, capillary blood glucose was measured using a reliable glucometer. The GI was calculated using the trapezoidal method.

RESULTS

The GI values of the following types of bread were: Barley 66, Lavash 72, Taftoon 79, Sangak 82, rye 84, and Barbari 99. The GI values for brown and white rice were 65 and 71, respectively. The mixture of brown rice with lentils had a GI value of 55, and the mixture of white rice with lentils had a GI of 79.

CONCLUSIONS

The most common types of bread and white rice consumed in Iran have high GI values. There is potential to reduce the overall GI values in the Iranian diet by encouraging the consumption of barley bread and brown rice.

Dietary patterns and cardiovascular disease in Australian adults: Findings from the 2011-12 Australian Health Survey

BACKGROUND AND AIMS

Great discrepancies exist in results from studies examining the association between dietary patterns and cardiovascular disease (CVD) in different populations. The aim of this study is to examine the relationship between the Australian Dietary Guidelines (ADG) 2013, Mediterranean-DASH diet Intervention for Neurodegenerative Delay (MIND), Paleolithic and Okinawan dietary patterns and CVD respectively.

METHODS AND RESULTS

In this cross-sectional secondary analysis of the 2011-12 Australian Health Survey, adults who self-reported physician-diagnosed CVD, completed two multiple-pass 24 h recalls and had no missing data on all confounders were analysed (weighted n = 5376; 295 CVD cases). Dietary intake was transformed to represent usual intake by the multiple source method. The score of Healthy Eating Index for Australian Adults (HEIFA-2013) was adopted for ADG 2013, while the scores of MIND, Paleolithic and Okinawan dietary patterns were constructed by separating the intake of each predefined food and nutrient into quintiles. The associations between the dietary patterns (as tertiles of scores) and CVD were examined using binary logistic regression adjusted for significant cardiovascular risk factors. Higher adherence to the Okinawan diet pattern was significantly associated with a reduced prevalence of ischemic heart disease (IHD) (OR per unit increase in dietary pattern score: 0.94, 95%CI: 0.90-0.98). Comparing its extreme tertiles, the OR was 0.49 (95%CI: 0.29-0.82; p_trend < 0.01). The associations between HEIFA-2013, MIND and Paleolithic diet patterns and CVD were insignificant.

CONCLUSION

The findings suggested an inverse association between adherence to Okinawan dietary pattern and prevalence of IHD in Australian adults.

Dietary fats and cardiometabolic disease: mechanisms and effects on risk factors and outcomes

The effect of dietary fats on cardiometabolic diseases, including cardiovascular diseases and type 2 diabetes mellitus, has generated tremendous interest. Many earlier investigations focused on total fat and conventional fat classes (such as saturated and unsaturated fats) and their influence on a limited number of risk factors. However, dietary fats comprise heterogeneous molecules with diverse structures, and growing research in the past two decades supports correspondingly complex health effects of individual dietary fats. Moreover, health effects of dietary fats might be modified by additional factors, such as accompanying nutrients and food-processing methods, emphasizing the importance of the food sources. Accordingly, the rapidly increasing scientific findings on dietary fats and cardiometabolic diseases have generated debate among scientists, caused confusion for the general public and present challenges for translation into dietary advice and policies. This Review summarizes the evidence on the effects of different dietary fats and their food sources on cell function and on risk factors and clinical events of cardiometabolic diseases. The aim is not to provide an exhaustive review but rather to focus on the most important evidence from randomized controlled trials and prospective cohort studies and to highlight current areas of controversy and the most relevant future research directions for understanding how to improve the prevention and management of cardiometabolic diseases through optimization of dietary fat intake.

Dietary glycemic index, glycemic load, and risk of mortality from all causes and cardiovascular diseases: a systematic review and dose-response meta-analysis of prospective cohort studies

BACKGROUND

Previous findings on the association of dietary glycemic index (GI) and glycemic load (GL) with mortality are conflicting.

OBJECTIVES

The aim of this study was to summarize earlier findings on the association between dietary GI and GL and the risk of cardiovascular disease (CVD) and all-cause mortality.

METHODS

A comprehensive literature search was performed of electronic databases, including MEDLINE (PubMed), Scopus, ISI Web of Science, EMBASE, and Google scholar, up to September 2018. Prospective cohort studies that reported GI and GL as the exposure and all-cause or CVD mortality as the outcome were included in the analysis. The random-effects model was used to estimate pooled RR and 95% CIs of all-cause and CVD mortality.

RESULTS

Eighteen cohort studies with a total of 251,497 participants, reporting 14,774 cases of all-cause mortality and 3658 cases of CVD mortality, were included in the present analysis. No significant association was found between dietary GI and all-cause mortality (RR: 1.07; 95% CI: 0.96, 1.19) and CVD mortality (RR: 1.02; 95% CI: 0.87, 1.20). In addition, dietary GL was not associated with all-cause mortality (RR: 1.08; 95% CI: 0.93, 1.27) or CVD mortality (RR: 1.07; 95% CI: 0.92, 1.25). However, the highest dietary GI, in comparison to the lowest one, significantly increased the risk of all-cause mortality in women (RR: 1.17; 95% CI: 1.02, 1.35). No evidence for a nonlinear association between dietary GI or GL and all-cause and CVD mortality was found (P > 0.05).

CONCLUSIONS

This meta-analysis of prospective cohort studies showed no significant association between either dietary GI or GL and all-cause and CVD mortality in men, but a positive association of GI with all-cause mortality in women.

Gestational Diabetes Mellitus: The Impact of Carbohydrate Quality in Diet

Gestational diabetes mellitus (GDM) is defined as “glucose intolerance that is first diagnosed during pregnancy”. Mothers with GDM and their infants may experience both short and long term complications. Dietary intervention is the first therapeutic strategy. If good glycaemic control is not achieved, insulin therapy is recommended. There is no consensus on which nutritional approach should be used in GDM. In the last few years, there has been growing evidence of the benefits of a low glycaemic index (LGI) diet on diabetes and cardiovascular disease. The effect of a LGI diet on GDM incidence has been investigated as well. Several studies observed a lower incidence of GDM in LGI diet arms, without adverse maternal and fetal outcomes. The main positive effect of the LGI diet was the reduction of 2-h post-prandial glucose (PPG). Several studies have also evaluated the effect of the LGI diet in GDM treatment. Overall, the LGI diet might have beneficial effects on certain outcomes, such as 2-h PPG, fasting plasma glucose and lipid profile in patients with GDM. Indeed, most studies observed a significant reduction in insulin requirement. Overall, according to current evidence, the LGI nutritional approach is safe and it might therefore be considered in clinical care for GDM.

Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations

While dietary factors are important modifiable risk factors for type 2 diabetes (T2D), the causal role of carbohydrate quality in nutrition remains controversial. Dietary glycemic index (GI) and glycemic load (GL) have been examined in relation to the risk of T2D in multiple prospective cohort studies. Previous meta-analyses indicate significant relations but consideration of causality has been minimal. Here, the results of our recent meta-analyses of prospective cohort studies of 4 to 26-y follow-up are interpreted in the context of the nine Bradford-Hill criteria for causality, that is: (1) Strength of Association, (2) Consistency, (3) Specificity, (4) Temporality, (5) Biological Gradient, (6) Plausibility, (7) Experimental evidence, (8) Analogy, and (9) Coherence. These criteria necessitated referral to a body of literature wider than prospective cohort studies alone, especially in criteria 6 to 9. In this analysis, all nine of the Hill's criteria were met for GI and GL indicating that we can be confident of a role for GI and GL as causal factors contributing to incident T2D. In addition, neither dietary fiber nor cereal fiber nor wholegrain were found to be reliable or effective surrogate measures of GI or GL. Finally, our cost-benefit analysis suggests food and nutrition advice favors lower GI or GL and would produce significant potential cost savings in national healthcare budgets. The high confidence in causal associations for incident T2D is sufficient to consider inclusion of GI and GL in food and nutrient-based recommendations.

Potato consumption and the risk of overall and cause specific mortality in the NIH-AARP study

BACKGROUND

Potato consumption has been hypothesized to be associated with higher risk of hypertension, diabetes, and colorectal cancer.

OBJECTIVE

The aim of this study was to examine the association between potato consumption and the risk of overall and cause specific mortality in the large prospective National Institutes of Health-AARP (NIH-AARP) Study.

DESIGN

The NIH-AARP study recruited 566,407 persons, aged 50-72 years in 1995-1996. We excluded subjects that reported a history of chronic disease at baseline. Potato consumption data from a validated food frequency questionnaire completed at baseline was used in Cox proportional hazard models to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for overall and cause specific mortality. Final models were adjusted for potential risk factors for mortality.

RESULTS

Among 410,701 participants included in this analysis, 76,921 persons died during the 15.6 years of follow-up. Eating baked, boiled, or mashed potatoes, French fries or potato salad seven or more times per week was associated with higher risk of overall mortality, in models adjusted only for age and sex (HR C4 vs C1 = 1.17, 95%CI = 1.13, 1.21). These results were attenuated in fully adjusted models (HR C4 vs C1 = 1.02, 95%CI = 0.97, 1.06). Potato consumption was not associated with risk of mortality caused by cancer (HR C4 vs C1 = 1.04, 95%CI = 0.97, 1.11), heart disease (HR C4 vs C1 = 1.00, 95%CI = 0.93, 1.09), respiratory disease (HR C4 vs C1 = 1.16, 95%CI = 0.99, 1.37), or diabetes (HR C4 vs C1 = 0.91, 95%CI = 0.71, 1.19). We tested for an association with different preparation methods and found limited evidence for differences by preparation method. The only statistically significant association was that for French fry consumption with cancer-related mortality (HR C4 vs C1 = 1.27, 95%CI = 1.02, 1.59), a finding for which uncontrolled confounding could not be ruled out.

CONCLUSION

We find little evidence that potato consumption is associated with all-cause or cause-specific mortality.

Diet, exercise and weight loss and dyslipidaemia

There is a large amount of controversy relating dietary fat intake and coronary artery disease. It has been strongly suggested that saturated fat is not harmful and that polyunsaturated fat is either not beneficial or even harmful. Given that dietary lipids and fibre can influence serum lipids which are strongly linked to the risk of coronary artery disease I have reviewed recent evidence linking diet and serum lipids to confirm a diet-heart disease link. Over 84 studies have been included in a recent meta-analysis and meta-regression which examined the effects of changes in fat type on lipid levels. An absolute 1% reduction in saturated fat or trans fat intake as a percentage of energy with replacement by n-6 polyunsaturated fat would lead to a reduction in low density lipoprotein (LDL) cholesterol of 0.05 mmol/L. In most Western countries the difference in intake between the highest quintile and the lowest quintile of saturated fat is about 7%, so moving from the highest to the lowest quintile should lower LDL cholesterol by 0.35 mmol/L or about 10%. This change should lower cardiovascular disease rates by at least 10%. Replacing this amount of saturated fat with carbohydrate of average quality would lower LDL cholesterol by 0.21 mmol/L and increase fasting triglyceride by 0.17 mmol/L. This combination of effects would have a neutral effect on cardiovascular disease rates. However, replacement of trans fat appears to reduce disease rates and total mortality. Substituting low glycaemic index carbohydrates for high glycaemic index carbohydrates will lower triglyceride by 15-25% and reduce cardiovascular risk. Large doses of fish oil will lower triglyceride with a mean lowering of 0.45 mmol/L for a 3.5 g/day amount. Large doses of soluble fibre (3.5-7.0 g/day) lower LDL cholesterol by 0.2-0.35 mmol/L with Konjac glucomannan being the most effective per gram. Plant sterols or stanols lower LDL cholesterol by about 10% for a 2 g/day dose, while exercise and weight loss lower cardiovascular risk predominantly by lowering fasting triglyceride. In conclusion, diet lowers LDL cholesterol and triglyceride and dietary changes should be ultimately linked to a reduced risk of heart disease.

Nature and Cognitive Perception of 4 Different Breakfast Meals Influence Satiety-Related Sensations and Postprandial Metabolic Responses but Have Little Effect on Food Choices and Intake Later in the Day in a Randomized Crossover Trial in Healthy Men

Background

Regular breakfast consumption is associated with better health status and healthier food intake throughout the day, but this association is a complex interaction of several factors.

Objective

This study aimed to investigate the effect of nutritional and cognitive-perceived characteristics of breakfast on metabolic and behavioral variables related to food intake.

Methods

The study was a randomized, crossover, controlled trial, with 4 experimental conditions consisting of 3 iso-energetic breakfasts and 1 energy-free control meal. Breakfasts had similar nutritional profiles but differed for glycemic index (GI), glycemic load (GL), and perceived healthiness, satiety, palatability, or energy content. Fifteen healthy normal-weight men [means ± SDs; age: 24 ± 2 y; body mass index (BMI; kg/m2) 23.4 ± 1.6] underwent each experimental condition in random order during 4 different weeks, separated by ≥1-wk washout. On the third day of each intervention week, postprandial blood variables (with insulin as primary outcome), satiety ratings, and food intake during an ad libitum lunch consumed 4 h after breakfast (secondary outcomes) were measured for each experimental condition.

Results

A main effect of time, treatment, and time × treatment was found for postprandial insulin, glucose, and nonesterified fatty acids (P < 0.001 for all) after having the 3 iso-energetic breakfasts or the energy-free control one. Postprandial satiety was similar for the 3 energy-containing breakfasts, but higher when compared with the energy-free control (P < 0.001). No difference in energy intake was observed for the ad libitum lunch, whereas prolonged breakfast skipping was compensated by an increase (around +10%) in the average energy intake during the rest of the day, resulting in no differences in the total daily energy intake among the 4 conditions.

Conclusions

Although other advantages might exist for breakfasts based on low-GI/low-GL foods, our findings support the hypothesis that minor differences in nutritional and perceived characteristics of breakfast are of limited importance regarding medium-term energy intake in healthy men. This trial was registered at clinicaltrials.gov as BRNN-014 NCT02516956.

Relevance of the Glycemic Index and Glycemic Load for Body Weight, Diabetes, and Cardiovascular Disease

Despite initial enthusiasm, the relationship between glycemic index (GI) and glycemic response (GR) and disease prevention remains unclear. This review examines evidence from randomized, controlled trials and observational studies in humans for short-term (e.g., satiety) and long-term (e.g., weight, cardiovascular disease, and type 2 diabetes) health effects associated with different types of GI diets. A systematic PubMed search was conducted of studies published between 2006 and 2018 with key words glycemic index, glycemic load, diabetes, cardiovascular disease, body weight, satiety, and obesity. Criteria for inclusion for observational studies and randomized intervention studies were set. The search yielded 445 articles, of which 73 met inclusion criteria. Results suggest an equivocal relationship between GI/GR and disease outcome. The strongest intervention studies typically find little relationship among GI/GR and physiological measures of disease risk. Even for observational studies, the relationship between GI/GR and disease outcomes is limited. Thus, it is unlikely that the GI of a food or diet is linked to disease risk or health outcomes. Other measures of dietary quality, such as fiber or whole grains may be more likely to predict health outcomes. Interest in food patterns as predictors of health benefits may be more fruitful for research to inform dietary guidance.

Global Correlates of Cardiovascular Risk: A Comparison of 158 Countries

The aim of this study was a large-scale ecological analysis of nutritional and other environmental factors potentially associated with the incidence of cardiovascular diseases (CVDs) in the global context. Indicators of CVDs from 158 countries were compared with the statistics of mean intake (supply) of 60 food items between 1993 and 2011, obesity rates, health expenditure and life expectancy. This comparison shows that the relationship between CVD indicators (raised blood pressure, CVD mortality, raised blood glucose) and independent variables in the global context is influenced by various factors, such as short life expectancy, religiously conditioned dietary customs, the imprecision of some statistics and undernutrition. However, regardless of the statistical method used, the results always show very similar trends and identify high carbohydrate consumption (mainly in the form of cereals and wheat, in particular) as the dietary factor most consistently associated with the risk of CVDs. These findings are in line with the changing view of the causes of CVDs. Because only the statistics of raised blood glucose include people using medications and reflect true prevalence that is independent of healthcare, more objective data on the prevalence of CVDs are needed to confirm these observed trends.

Diet and Cardiovascular Disease: Advances and Challenges in Population-Based Studies

In this Minireview, we provide an epidemiologist's perspective on the debate and recent advances in determining the relationship between diet and cardiovascular health. We conclude that, in order to reduce the global burden of cardiovascular disease, there should be a greater emphasis on improving overall diet quality and food sources of macronutrients, such as dietary fats and carbohydrates. In addition, building a strong evidence base through high-quality intervention and observational studies is crucial for effective policy changes, which can greatly improve the food environment and population health.

Nutrients and Oxidative Stress: Friend or Foe?

There are different types of nutritionally mediated oxidative stress sources that trigger inflammation. Much information indicates that high intakes of macronutrients can promote oxidative stress and subsequently contribute to inflammation via nuclear factor-kappa B- (NF-κB-) mediated cell signaling pathways. Dietary carbohydrates, animal-based proteins, and fats are important to highlight here because they may contribute to the long-term consequences of nutritionally mediated inflammation. Oxidative stress is a central player of metabolic ailments associated with high-carbohydrate and animal-based protein diets and excessive fat consumption. Obesity has become an epidemic and represents the major risk factor for several chronic diseases, including diabetes, cardiovascular disease (CVD), and cancer. However, the molecular mechanisms of nutritionally mediated oxidative stress are complex and poorly understood. Therefore, this review aimed to explore how dietary choices exacerbate or dampen the oxidative stress and inflammation. We also discussed the implications of oxidative stress in the adipocyte and glucose metabolism and obesity-associated noncommunicable diseases (NCDs). Taken together, a better understanding of the role of oxidative stress in obesity and the development of obesity-related NCDs would provide a useful approach. This is because oxidative stress can be mediated by both extrinsic and intrinsic factors, hence providing a plausible means for the prevention of metabolic disorders.

A nutritional evaluation of various typical Italian breakfast products: a comparison of macronutrient composition and glycaemic index values

Breakfast foods with lower glycaemic responses are associated with better body weight control. Glycaemic index (GI) values of some commonly consumed breakfast foods in Italy were determined and compared, along with macronutrients. Cakes/pastries were low-medium GI (44-60), with high-sugar and saturated fat and low-fibre. Generally, mueslis and breads were medium GI (62-66 and 59-76, respectively) with higher fibre and lower saturated fat and sugar. The addition of spreads to bread lowered GI (47-66) but increased sugar and saturated fat.

Low glycaemic index diets for the prevention of cardiovascular disease

BACKGROUND

The glycaemic index (GI) is a physiological measure of the ability of a carbohydrate to affect blood glucose. Interest is growing in this area for the clinical management of people at risk of, or with, established cardiovascular disease. There is a need to review the current evidence from randomised controlled trials (RCTs) in this area. This is an update of the original review published in 2008.

OBJECTIVES

To assess the effect of the dietary GI on total mortality, cardiovascular events, and cardiovascular risk factors (blood lipids, blood pressure) in healthy people or people who have established cardiovascular disease or related risk factors, using all eligible randomised controlled trials.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and CINAHL in July 2016. We also checked reference lists of relevant articles. No language restrictions were applied.

SELECTION CRITERIA

We selected RCTs that assessed the effects of low GI diets compared to diets with a similar composition but a higher GI on cardiovascular disease and related risk factors. Minimum trial duration was 12 weeks. Participants included were healthy adults or those at increased risk of cardiovascular disease, or previously diagnosed with cardiovascular disease. Studies in people with diabetes mellitus were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently screened and selected studies. Two review authors independently assessed risk of bias, evaluated the overall quality of the evidence using GRADE, and extracted data following the Cochrane Handbook for Systematic Reviews of Interventions. We contacted trial authors for additional information. Analyses were checked by a second reviewer. Continuous outcomes were synthesized using mean differences and adverse events were synthesized narratively.

MAIN RESULTS

Twenty-one RCTs were included, with a total of 2538 participants randomised to low GI intervention (1288) or high GI (1250). All 21 included studies reported the effect of low GI diets on risk factors for cardiovascular disease, including blood lipids and blood pressure.Twenty RCTs (18 of which were newly included in this version of the review) included primary prevention populations (healthy individuals or those at high risk of CVD, with mean age range from 19 to 69 years) and one RCT was in those diagnosed with pre-existing CVD (a secondary prevention population, with mean age 26.9 years). Most of the studies did not have an intervention duration of longer than six months. Difference in GI intake between comparison groups varied widely from 0.6 to 42.None of the included studies reported the effect of low GI dietary intake on cardiovascular mortality and cardiovascular events such as fatal and nonfatal myocardial infarction, unstable angina, coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, and stroke. The unclear risk of bias of most of the included studies makes overall interpretation of the data difficult. Only two of the included studies (38 participants) reported on adverse effects and did not observe any harms (low-quality evidence).

AUTHORS' CONCLUSIONS

There is currently no evidence available regarding the effect of low GI diets on cardiovascular disease events. Moreover, there is currently no convincing evidence that low GI diets have a clear beneficial effect on blood lipids or blood pressure parameters.

Postprandial Effects of Breakfast Glycemic Index on Vascular Function among Young Healthy Adults: A Crossover Clinical Trial

This study aimed to evaluate the postprandial effects of high and low glycemic index (GI) breakfasts on vascular function. It was a crossover trial that included 40 young healthy adults (50% women), aged 20-40 years, who were recruited at primary care settings. They consumed three experimental breakfasts in randomized order, each one separated by a 1-week washout period: (1) control conditions (only water); (2) low GI (LGI) breakfast (29.4 GI and 1489 KJ energy); and (3) high GI (HGI) breakfast (64.0 GI and 1318 KJ energy). Blood samples were collected at 60 and 120 min after each breakfast to determine glucose and insulin levels. Vascular parameters were measured at 15 min intervals. Augmentation index (AIx) was studied as a primary outcome. Secondary outcomes comprised glucose, insulin, heart rate (HR) and pulse pressures (PPs). We found a trend toward increased AIx, HR and PPs for the HGI versus the LGI breakfast. A significant interaction between the type of breakfast consumed and all measured parameters was identified (p < 0.05) except for central PP. Stratifying data by sex, this interaction remained significant for AIx and augmentation pressure only in males (p < 0.05). In conclusion, breakfast GI could affect postprandial vascular responses in young healthy adults.

Changes in dietary glycemic index and glycemic load in Australian adults from 1995 to 2012

Background: Australians have used the glycemic index (GI) since 1995; however, there are no data on changes in carbohydrate quality over time.Objectives: The aim was to compare average dietary GI and glycemic load (GL), and contributing carbohydrate foods, in the 2 most recent national dietary surveys.Design: Dietary data from adult participants of national nutrition surveys conducted in 1995 (the 1995 Australian National Nutrition Survey; n = 8703) and 2012 (the 2011-2012 National Nutrition and Physical Activity Survey; n = 6278), collected by a single 24-h recall, were analyzed. The differences in mean dietary GI and GL between surveys were compared by using 1-factor ANOVA. The main sources of dietary GL in the 2 surveys were also assessed. Multiple linear regression was performed to examine the contributions of the food groups to interindividual variations in dietary GI and GL.Results: Overall, dietary GI and GL decreased by 5% and 12%, respectively, from 1995 to 2012 (GI on glucose standard: 56.5 ± 6.2 compared with 53.9 ± 6.8, respectively; GL: 153.3 ± 62.1 compared with 135.4 ± 58.5, respectively; both P < 0.001). Breads were the main contributor to GL at both time points. Potatoes and sweetened beverages contributed less, whereas cereal-based dishes contributed more in 2012 than in 1995. The top 20 GL-contributing food groups explained less interindividual variation in dietary GI (R²: 0.376 compared with 0.290) and GL (R²: 0.825 compared with 0.770) in 2012 than in 1995.Conclusion: Although the average dietary GI and GL declined between 1995 and 2012, trends in specific carbohydrate foods suggest that Australians are avoiding potatoes and sugary beverages in favor of a greater variety of carbohydrate foods, particularly cereal products.

Cross-sectional associations between dietary intake and carotid intima media thickness in type 2 diabetes: baseline data from a randomised trial

OBJECTIVE

To assess associations between dietary intake and carotid intima media thickness (CIMT) by carotid ultrasound (CUS), a surrogate marker of cardiovascular disease (CVD) risk, in those with type 2 diabetes.

DESIGN

Cross-sectional analysis of baseline data from 325 participants from three randomised controlled trials collected in the same way.

SETTING

Risk Factor Modification Centre, St. Michael's Hospital, Toronto, Canada.

PARTICIPANTS

325 participants with type 2 diabetes, taking oral antidiabetic agents, with an HbA1c between 6.5% and 8.0% at screening, without a recent cardiovascular event.

MAIN OUTCOME MEASURES

CIMT by CUS and associations with dietary intake from 7-day food records, as well as anthropometric measures and fasting serum samples.

RESULTS

CIMT was significantly inversely associated with dietary pulse intake (β=-0.019, p=0.009), available carbohydrate (β=-0.004, p=0.008), glycaemic load (β=-0.001, p=0.007) and starch (β=-0.126, p=0.010), and directly associated with total (β=0.004, p=0.028) and saturated (β=0.012, p=0.006) fat intake in multivariate regression models adjusted for age, smoking, previous CVD event, blood pressure medication, antidiabetic medication and ultrasonographer.

CONCLUSIONS

Lower CIMT was significantly associated with greater consumption of dietary pulses and carbohydrates and lower total and saturated fat intake, suggesting a potential role for diet in CVD risk management in type 2 diabetes. Randomised controlled trials are anticipated to explore these associations further.

TRIAL REGISTRATION NUMBER

NCT01063374.

Dietary glycaemic index and glycaemic load among Australian adults - results from the 2011-2012 Australian Health Survey

This study aimed to determine the major food groups contributing to dietary glycaemic load (GL). Plausible food intake data collected using a multiple-pass 24 hour recall from a weighted sample of 6326 adult respondents (52% male) of the 2011-2012 Australian Health Survey dataset (AHS) were analysed. The GI of foods was estimated based on a previously published step-wise method. Descriptive statistics were calculated for dietary glycaemic index (GI), GL and contribution to GL by major food groups, stratified by age and sex. Trends across age groups were assessed using linear regression. Pearson's χ² was used to test for differences between age groups for categorical demographics variables. The mean (SD) dietary GI and GL was 54 (7) and 135 (59) respectively and the top 3 contributors to dietary GL were breads (14.4%), cereal-based dishes (10.3%) and breakfast cereals (ready to eat) (6.6%). There were small but significant differences in the GL contribution pattern between the sexes. The findings indicate that the average dietary GI of Australian adults is similar to that of other population groups, with a large proportion of starchy and energy-dense nutrient-poor foods that contribute to a high GL.

A rat model for determining the postprandial response to foods

BACKGROUND

The use of small animal models for studying postprandial changes in circulating nutrients, hormones and metabolic biomarkers is hampered by the limited quantity of blood that can be withdrawn for analysis. Here, we describe the development of an unrestrained, meal-fed rat model, having a permanent or temporary vascular cannula that permits repeated blood sampling. The applicability and performance of the model were evaluated in a series of experiments on acute glycaemic and insulinaemic responses to carbohydrate-based test meals.

RESULTS

A test food containing 0.4 g carbohydrate raised blood glucose by 1.5 mmol L^-1 . Postprandial blood glucose levels peaked at 15 min and returned to baseline at 180 min, whereas they remained elevated for longer when the test meal contained 1.25 g carbohydrate. The glycaemic response tended (P = 0.063) to be higher when the meal tolerance test was conducted at the start rather than the end of the dark period, but the insulinaemic response was unaffected. The magnitude of the glycaemic response was less for blood collected from the caudal vein compared to that from the jugular vein. Both cannulation strategies were equally effective in enabling return of red blood cells, thus preserving blood volume.

CONCLUSION

This improved small animal model affords new opportunities to screen foods for nutrient bioavailability and explore metabolic mechanisms mediating responses to food consumption. © 2016 Society of Chemical Industry.

Postprandial effect of breakfast glycaemic index on vascular function, glycaemic control and cognitive performance (BGI study): study protocol for a randomised crossover trial

Background

Postprandial glycaemic response affects cognitive and vascular function. The acute effect of breakfast glycaemic index on vascular parameters is not sufficiently known. Also, the influence of breakfasts with different glycaemic index on cognitive performance has been mostly studied in children and adolescents with varying results. Therefore, the purpose of this study is to analyse the postprandial effect of high and low glycaemic index breakfasts on vascular function and cognitive performance and their relationship with postprandial glycaemic response in healthy young adults.

Methods/design

This is a crossover clinical trial targeting adults (aged 20–40 years, free from cardiovascular disease) selected by consecutive sampling at urban primary care health clinics in Salamanca (Spain). Each subject will complete three interventions with a washout period of one week: a control condition (consisting of water); a low glycaemic index breakfast (consisting of dark chocolate, walnuts, yogurt and an apple, with an overall glycaemic index of 29.4 and an energy contribution of 1489 kJ); and a high glycaemic index breakfast (consisting of bread, grape juice and strawberry jam, with an overall glycaemic index of 64.0 and an energy contribution of 1318 kJ). The postprandial effect will be assessed at 60 and 120 minutes from each breakfast including blood sampling and cognitive performance evaluations. Measurements of arterial stiffness and central haemodynamic parameters will be taken at –10, 0, 15, 30, 45, 60, 75, 90, 105 and 120 minutes.

Discussion

The differences in postprandial glycaemic response due to breakfast glycaemic index could affect vascular parameters and cognitive performance with important applications and implications for the general population. This could provide necessary information for the establishment of new strategies in terms of nutritional education and work performance improvement.

Trial registration

ClinicalTrials.gov: NCT02616276. Registered on 19 November 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1649-x) contains supplementary material, which is available to authorized users.

Dietary fat and carbohydrate quality have independent effects on postprandial glucose and lipid responses

PURPOSE

The magnitude of postprandial lipemia is influenced not only by the amount but also the type of fat and carbohydrate consumed. The aim of this study was to evaluate differences in postprandial glucose and lipid responses after a mixed meal containing low- or high-glycemic-index (GI) carbohydrate and three different types of fat varying in the degree of saturation in healthy subjects.

METHODS

A randomized, controlled, single-blinded crossover study was conducted in 20 healthy Chinese men. Subjects consumed in random order six experimental isocaloric meals that differed in carbohydrate and fat quality, and contained 40 g of either saturated fat (SFA, butter), monounsaturated fat (MUFA, olive oil) or polyunsaturated fat (PUFA, grapeseed oil), and 50 g of either low-GI (basmati rice) or high-GI (jasmine rice) carbohydrate. Glucose, insulin, c-peptide, triglycerides (TG) and non-esterified fatty acids (NEFA) were measured over 4 h.

RESULTS

For all substrates evaluated, there were no significant interactions between fat and carbohydrate. The incremental area under the curve (iAUC) for TG was significantly lower after the SFA and PUFA meals compared with the MUFA meal, irrespective of GI. No significant difference was found for NEFA iAUC in all treatments. Glucose, insulin and c-peptide iAUCs were significantly lower after ingestion of low-GI than high-GI meals, independent of the type of fat.

CONCLUSIONS

A carbohydrate-rich meal (of either low or high GI) that contains butter or grapeseed oil results in lower postprandial TG concentrations relative to olive oil in healthy Chinese males. Glucose, insulin and c-peptide responses, however, are directly dependent on the GI of the meal and not on the degree of saturation of dietary fat. The trial was registered at clinicaltrials.gov as NCT02585427.

Dietary glycemic index and retinal microvasculature in adults: a cross-sectional study

Objective

To analyze the relationship between dietary glycemic index (GI) and retinal microvasculature in adults.

Methods

This was a cross-sectional study of 300 subjects from the EVIDENT II study. Dietary GI was calculated using a validated, semi-quantitative food frequency questionnaire. Retinal photographs were digitized, temporal vessels were measured in an area 0.5–1 disc diameter from the optic disc and arteriolar-venular index (AVI) was estimated with semi-automated software.

Results

AVI showed a significant difference between the tertiles of GI, after adjusting for potential confounders. The lowest AVI values were observed among subjects in the highest tertile of GI, whereas the greatest were found among those in the lowest tertile (estimated marginal mean of 0.738 vs. 0.768, p = 0.014).

Conclusions

In adults, high dietary GI implies lowering AVI values regardless of age, gender and other confounding variables.

Trial registration

Clinical Trials.gov Identifier: NCT02016014. Registered 9 December 2013.