Glycaemic glucose equivalent: combining carbohydrate content, quantity and glycaemic index of foods for precision in glycaemia management

Anti-Diabetic Potential of Polyphenol-Rich Fruits from the Maleae Tribe-A Review of In Vitro and In Vivo Animal and Human Trials

The Maleae tribe consists of over one thousand species, including many well-known polyphenol-containing fruit crops with wide-ranging biological properties, e.g., apples (Malus), chokeberries (Aronia), pears (Pyrus), quinces (Cydonia, Chaenomeles), saskatoon (Amelanchier), loquats (Eriobotrya), medlars (Mespilus), rowans (Sorbus), and hawthorns (Crataegus). Considering the current interest in the concept of functional foods and the still-insufficient methods of diabetes management, the anti-diabetic potential of fruits has been studied intensively, including those of the Maleae tribe. This paper is the first comprehensive overview of this selected topic, covering articles published from 2000 to 2023 (131 articles in total). The first part of this review focuses on the potential mechanisms of action of fruits investigated so far (46 species), including their effects on tissue-specific glucose transport and the expression or activity of proteins in the insulin signalling pathway. The second part covers the phytocompounds responsible for particular fruits' activity-primarily polyphenols (e.g., flavonols, dihydrochalcones, proanthocyanidins, anthocyanins, phenolic acids), but also polysaccharides, triterpenes, and their additive and synergistic effects. In summary, fruits from the Maleae tribe seem promising as functional foods and anti-diabetic agents; however, their prospects for more expansive pro-health application require further research, especially more profound in vivo trials.

Potential contributions of the methodology to the variability of glycaemic index of foods

Glycaemic index (GI) testing provides a useful point of comparison between carbohydrate sources. For this comparison to be meaningful, the methods used to determine GI values need to be rigorous and consistent between testing events. This requirement has led to increasing standardization of the GI methodology, with an international standard developed in joint consultation with FAO/WHO (ISO 26642:2010) currently the most up to date document. The purpose of this review is to compare the international standard to methods of published studies claiming to have performed a GI test. This analysis revealed that the international standard permits a wide range of choices for researchers when designing a GI testing plan, rather than a single standardized protocol. It has also been revealed that the literature contains significant variation, both between studies and from the international standard for critical aspects of GI testing methodology. The primary areas of variation include; what glucose specification is used, which reference food is used, how much reference food is given, what drink is given during testing, the blood sampling site chosen and what assay and equipment is used to measure blood glucose concentration. For each of these aspects we have explored some of the methodological and physiological implications of these variations. These insights suggest that whilst the international standard has assisted with framing the general parameters of GI testing, further stan-dardization to testing procedures is still required to ensure the continued relevance of the GI to clinical nutrition.

Minimally processed foods are more satiating and less hyperglycemic than ultra-processed foods: a preliminary study with 98 ready-to-eat foods

Beyond nutritional composition, food structure is increasingly recognized to play a role in food health potential, notably in satiety and glycemic responses. Food structure is also highly dependent on processing conditions. The hypothesis for this study is, based on a data set of 98 ready-to-eat foods, that the degree of food processing would correlate with the satiety index (SI) and glycemic response. Glycemic response was evaluated according to two indices: the glycemic index (GI) and a newly designed index, the glycemic glucose equivalent (GGE). The GGE indicates how a quantity of a certain food affects blood glucose levels by identifying the amount of food glucose that would have an effect equivalent to that of the food. Then, foods were clustered within three processing groups based on the international NOVA classification: (1) raw and minimally processed foods; (2) processed foods; and (3) ultra-processed foods. Ultra-processed foods are industrial formulations of substances extracted or derived from food and additives, typically with five or more and usually many (cheap) ingredients. The data were correlated by nonparametric Spearman's rank correlation coefficient on quantitative data. The main results show strong correlations between GGE, SI and the degree of food processing, while GI is not correlated with the degree of processing. Thus, the more food is processed, the higher the glycemic response and the lower its satiety potential. The study suggests that complex, natural, minimally and/or processed foods should be encouraged for consumption rather than highly unstructured and ultra-processed foods when choosing weakly hyperglycemic and satiating foods.

Slowly digestible starch--a review

The link between carbohydrate intake and health is becoming increasingly important for consumers, particularly in the areas of glycemic index (GI) and extended energy-releasing starches. From a physiological point of view, slowly digestible starch (SDS) delivers a slow and sustained release of blood glucose along with the benefits resulting from low glycemic and insulinemic response. SDS has been implicated in several health problems, including diabetes, obesity, and cardiovascular diseases (metabolic syndromes). It may also have commercial potential as a novel functional ingredient in a variety of fields, such as nutrition, medicine, and agriculture. The present review assesses this form of digestion by analyzing methods to prepare and evaluate SDS, and factors affecting its transformation, its health benefits, and its applications.

Intensive low-glycaemic-load dietary intervention for the management of glycaemia and serum lipids among women with gestational diabetes: a randomized control trial

OBJECTIVE

The present study aimed to compare the effects of a general dietary intervention and an intervention with low glycaemic load (GL) on glycaemic control, blood lipid metabolism and pregnancy outcomes in women with gestational diabetes mellitus.

DESIGN

Participants were randomly assigned to two groups, receiving either an individualized general dietary intervention (Control group) or an intensive low-GL intervention (Low-GL group) every two weeks, from 24-26 weeks of gestation to delivery.

SETTING

The Center of Maternal Primary Care in Guangdong General Hospital, China.

SUBJECTS

Ninety-five women with gestational diabetes mellitus were enrolled from June 2008 to July 2009.

RESULTS

After the intervention, both groups significantly decreased their dietary intakes of energy, fat and carbohydrate. The Low-GL group had significantly lower values for GL (122 v. 136) and glycaemic index (50 v. 54) but greater dietary fibre intake (33 v. 29 g/d) than did the Control group (all P<0·01). Significantly greater decreases in fasting plasma glucose (-0·33 v. -0·02 mmol/l, P<0·01) and 2 h postprandial glucose (-2·98 v. -2·51 mmol/l, P<0·01), significantly lower increases in total cholesterol (0·12 v. 0·23 mmol/l) and TAG (0·41 v. 0·56 mmol/l) and a significantly lower decrease in HDL cholesterol (-0·01 v. -0·11 mmol/l) were also observed in the Low-GL group compared with the Control group (all P<0·05). There were no significant differences in body weight gain, birth weight or other maternal-fetal perinatal outcomes between the two groups.

CONCLUSIONS

The low-GL targeted dietary intervention outperformed the general dietary intervention in glycaemic control and the improvement of blood lipid levels in women with gestational diabetes mellitus.

Celiac disease and overweight in children: an update

The clinical presentation of celiac disease in children is very variable and differs with age. The prevalence of atypical presentations of celiac disease has increased over the past 2 decades. Several studies in adults and children with celiac disease indicate that obesity/overweight at disease onset is not unusual. In addition, there is a trend towards the development of overweight/obesity in celiac patients who strictly comply with a gluten-free diet. However, the pathogenesis and clinical implications of the coexistence of classic malabsorption (e.g., celiac disease) and overweight/obesity remain unclear. This review investigated the causes and main clinical factors associated with overweight/obesity at the diagnosis of celiac disease and clarified whether gluten withdrawal affects the current trends of the nutritional status of celiac disease patients.

Carbohydrate nutrition differs by diabetes status and is associated with dyslipidemia in Boston Puerto Rican adults without diabetes

Puerto Rican adults have a greater prevalence of type 2 diabetes (T2D) and lower HDL-cholesterol (HDL-C) than the general U.S. population. Carbohydrate nutrition may play a role in this disparity. Cross-sectional analyses included data from 1219 Puerto Ricans aged 45-75 y enrolled in the Boston Puerto Rican Health Study. Using the Pearson chi-square test and ANCOVA, lifestyle characteristics and dietary intake, as assessed by semiquantitative FFQ, were compared by T2D status based on fasting plasma glucose concentration and medication use. Food source rankings for carbohydrate, dietary glycemic load (GL), and fiber were obtained using the SAS procedure PROC RANK. Geometric mean plasma HDL-C and TG concentrations were compared across quintiles of dietary carbohydrate, glycemic index (GI), GL, and fiber by using ANCOVA and tests for linear trend. In multivariable analyses, individuals with T2D (39.5%) had lower dietary carbohydrate, GL, and total sugar intake from lower intake of sugar, fruit drinks, and soda compared with those without T2D. In individuals without T2D, dietary carbohydrate and GL were inversely associated with HDL-C (P < 0.0001). Associations between dietary fiber and HDL-C were confounded by carbohydrate intake, apparently from concurrent consumption of legumes with white rice, a refined carbohydrate food. No associations were observed between carbohydrate, dietary GI, GL, or fiber and TG. In conclusion, individuals with T2D showed evidence of dietary modification. Among those without diabetes, a high intake of refined carbohydrates was associated with decreased HDL-C. Longitudinal research on carbohydrate nutrition in relation to diabetes risk factors and blood lipids in Puerto Ricans is warranted.

Glycaemic index methodology

The glycaemic index (GI) concept was originally introduced to classify different sources of carbohydrate (CHO)-rich foods, usually having an energy content of >80 % from CHO, to their effect on post-meal glycaemia. It was assumed to apply to foods that primarily deliver available CHO, causing hyperglycaemia. Low-GI foods were classified as being digested and absorbed slowly and high-GI foods as being rapidly digested and absorbed, resulting in different glycaemic responses. Low-GI foods were found to induce benefits on certain risk factors for CVD and diabetes. Accordingly it has been proposed that GI classification of foods and drinks could be useful to help consumers make 'healthy food choices' within specific food groups. Classification of foods according to their impact on blood glucose responses requires a standardised way of measuring such responses. The present review discusses the most relevant methodological considerations and highlights specific recommendations regarding number of subjects, sex, subject status, inclusion and exclusion criteria, pre-test conditions, CHO test dose, blood sampling procedures, sampling times, test randomisation and calculation of glycaemic response area under the curve. All together, these technical recommendations will help to implement or reinforce measurement of GI in laboratories and help to ensure quality of results. Since there is current international interest in alternative ways of expressing glycaemic responses to foods, some of these methods are discussed.

Glycemic impact and health: new horizons in white bread formulations

The challenge of provision of a much wider range of foods of relatively low glycemic response than is currently available, especially in terms of cereal products, has been highlighted in recent years and this has particular relevance to bread consumption. Although there has been some transition to brown bread consumption, white bread remains a firm feature in the typical average western diet. This review first outlines the relationship between the glycemic impact of foods and health. What is important is that relatively small differences in glycemic potency of regularly consumed starch foods have been shown to have beneficial effects on health outcomes. Second, factors affecting glycemic response with particular application to white bread formulations are discussed. Novel ways of reformulating this highly favored carbohydrate staple, by using composite flours, with the aim of developing products of reduced glycemic response are highlighted in this review. Importantly, a new and significant focus on the role of unavailable carbohydrate in glycemic improvement is emerging. This has important application in increasing accessibility to health benefits by contributing to the prevention of and management of glucose intolerance, insulin resistance, and associated chronic disease to a wider range of consumers.

Acculturation and sociocultural influences on dietary intake and health status among Puerto Rican adults in Massachusetts

BACKGROUND

Previous studies have shown negative consequences of acculturation on lifestyle factors, health status, and dietary intake of Hispanic immigrants in the US. Despite prevalent type 2 diabetes and low socioeconomic status (SES) among Puerto Rican adults living on the US mainland, little is known about acculturation in this group.

OBJECTIVE

We investigated associations among acculturation, lifestyle characteristics, health status, and carbohydrate nutrition in Puerto Rican adults. A secondary objective was to investigate possible confounding and/or effect modification on these associations by SES.

DESIGN

Cross-sectional data from the Boston Puerto Rican Health Study, which included 1219 Puerto Ricans in the Boston area, aged 45-75 years.

STATISTICAL ANALYSES

Characteristics were compared using ANCOVA, linear trend and Pearson's chi-square tests across quartiles of acculturation. Tests for interaction by poverty status were conducted. Proportional contributions of foods to intake of total carbohydrate and fiber were assessed using SAS RANK.

RESULTS

Levels of acculturation were low, despite young age at first arrival to the US mainland (25.4 ± 12.3 y) and long length of stay (34.2 ± 12.2 y). Greater English language use was associated with higher SES, alcohol consumption, physical activity, better perceived health, and less central obesity. Acculturation was associated with lower legume fiber and greater cereal fiber intake. Among those above the poverty threshold, acculturation was associated with lower dietary glycemic index and starch intake, and greater fruit and non-starchy vegetable intake.

CONCLUSIONS

In contrast to studies with Mexican Americans, the association of acculturation with dietary quality in these Puerto Rican adults was mixed, but tended toward better carbohydrate quality. Dietary recommendations should include maintenance of traditional, healthful dietary practices including consumption of legumes, but also reduction in refined grains, and greater inclusion of fruit, non-starchy vegetables, and whole grains. Interventions to improve access to better quality carbohydrate sources are necessary for this group disproportionately affected by diabetes.

Glycemic and insulinemic responses to carbohydrate rich whole foods

Glycemic and insulinemic responses to food may depend on several intrinsic factors such as the type of sugar, molecular arrangement, size of starch granules, co-components in the whole food like moisture, fat, protein, fiber, as well as external factors like processing technique and total amount consumed. The postprandial glycemic response to equivalent quantities of test food and standard food is compared using Glycemic Index food (GI food). The incremental area under the curve for blood glucose and insulin at fasting, 30, 60, 90 and 120 min after consumption of different doses (50 and 100 g) of carbohydrate rich foods like rice and chapatti were compared with standard food, white bread. The GI food value for 50 g of chapatti and rice was 44 and 11 respectively. The Insulinemic Index food (II food) values, calculated similarly, for 50 g portion of chapatti and rice were 39 and 6 respectively. Glycemic and insulinemic response showed a dose dependent increase from 50 to 100 g. Both glycemic and insulinemic impact of chapatti were found to be significantly higher than that of rice (p < 0.05). The GI food and II food values will facilitate qualitative and quantitative judgment about the selection of specific foods for effective metabolic control.

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.

Considerable temporal variability in glucose reference curves in humans for a year period

Glycemic glucose equivalent (GGE) is a measure of the blood glucose response to a defined portion of food. Their calculation requires the measurement of a standard glucose-response curve, with beverages containing 0, 12.5, 25, 50, and 75 g of glucose measured twice each. This study was designed to determine the stability of an individual's glucose-response curve measured every 3 months for a year and of their GGE estimates for 10 foods for that period. The blood glucose response to beverages containing 0, 12.5, 25, 50, and 75 g glucose and to 10 foods was measured for 16 healthy individuals. Capillary blood samples were collected fasting, then every 15 minutes for 1 hour, and every 30 minutes for at least 2 hours. The slopes and intercepts of the 4 glucose curves and the GGE of the 10 foods calculated using the available curves for each food was compared. The results showed considerable temporal variability in the slope (intraindividual coefficient of variation (CV) = 30%) and intercept (intraindividual CV = 40%) of the glucose curves. However, if GGE values were categorized into 3 groups (low GGE, < or = 10; medium GGE, 10.01-19.99; and high GGE, > or = 20), all but one food was consistently classified in the same category across the 4 glucose curves. In conclusion, it appears that if the exact GGE value is required, glucose curves should be repeated at least once every 3 months, but if foods are classed into general GGE categories, it may be possible to use the same glucose curve for a longer period.

Glycemic response and health--a systematic review and meta-analysis: relations between dietary glycemic properties and health outcomes

BACKGROUND

Reduction of dietary glycemic response has been proposed as a means of reducing the risk of diabetes and coronary heart disease. The impact of glycemic response on markers of health remains to be elucidated.

OBJECTIVE

We assessed the evidence relating the glycemic impact of foods to measures relevant for health maintenance and management of disease.

DESIGN

This was a systematic review and synthesis of interventional evidence from literature reported on glycemic index and markers of health through the use of meta-analyses and meta-regression models.

RESULTS

Data from 45 relevant publications were found to January 2005. Lower glycemic index (GI) diets reduced both fasting blood glucose and glycated proteins independently of variance in available and unavailable carbohydrate intakes. Elevated unavailable carbohydrate added to improvements in both blood glucose and glycated protein control. These effects were greater in persons with poor fasting blood glucose control. No effects were seen on fasting insulin<100 pmol/L; above this, study numbers were few but consistent with prevention of hyperinsulinemia in some but not all overweight persons. Insulin sensitivity according to a variety of measurement methods was improved by lower GI, higher unavailable carbohydrate interventions in persons with type 2 diabetes, in overweight and obese persons, and in all studies combined. Fasting triacylglycerol in addition to body weight reduction related more to glycemic load than to GI. Glycemic load reduction by >17 g glucose equivalents/d was associated with reduced body weight.

CONCLUSIONS

Consumption of reduced glycemic response diets are followed by favorable changes in the health markers examined. The case for the use of such diets looks compelling. Unavailable carbohydrate intake is equally important.

Low-glycaemic diets and health: implications for obesity

The present review considers the background to terminology that relates foods, glycaemia and health, including ‘available carbohydrate’, ‘glycaemic index’ (GI), 'glycaemic glucose equivalent', 'glycaemic response index' and 'net carbohydrate', and concludes that central to each of these terms is 'glycaemic load' (GL). GL represents the acute increase in exposure of tissue to glucose determined by foods; it is expressed in ingested glucose equivalents (per 100 g fresh weight or per serving), and is regarded as independent of the state of glucose metabolism from normal to type 2 diabetes mellitus (T2DM). Ad libitum studies in overweight or obese adults and children show that low-GL diets are associated with marked weight benefits, loss of adiposity and reduced food intake. Weight benefits appear on low-glycaemic v. high-glycaemic available carbohydrates, unavailable v. available carbohydrates and protein v. available carbohydrate. Energy intake immediately after lowering of meal GL via carbohydrate exchanges is apparent only after a threshold cumulative intake of >2000 MJ. Various epidemiological and interventional studies are discussed. A relationship between GL and the development of T2DM and CHD is evident. Studies that at first seem conflicting are actually consistent when data are overlaid, such that diets with a GL of >120 glucose equivalents/d would appear to be inadvisable. Whereas certain studies might place GI as being slightly stronger than GL in relationto T2DM risk, this situation appears to be associated with observations in a lower range of GL or when the range of GI is too narrow for accuracy; nevertheless, authors emphasise the importance of GL. Among the studies reviewed, GL offers a better or stronger explanation than GI in various observations including body weight, T2DM in nurses, CHD, plasma triacylglycerols, HDL-cholesterol, high-sensitivity C-reactive protein and protein glycation. Where information is available, the associations between risk factors and GL are either similar or stronger in the overweight or obese, as judged by BMI, and apply to both body weight and blood risk factors. The implications tend to favour a long-term benefit of reducing GL, for which further study is necessary to eliminate any possibility of publication bias and to establish results in clinical trials with overweight and obese patients.

Virtual food components: functional food effects expressed as food components

BACKGROUND

The ability to communicate food benefits is essential for the successful development of functional foods and their role in improving public health. However, the functional efficacy of foods often cannot be represented by food composition. The concept of virtual food components (VFCs)-food data that express health-related effects, properties or functions of foods in the format of food components-is therefore proposed.

OBJECTIVE

To develop protocols for designing VFC data sets that communicate functional efficacies of foods to end users, in order to facilitate evidence-based food choice, and allow data management systems to provide a more complete description of nutritional effects of foods than has been possible with values for actual food components alone.

METHOD

A framework within which to develop VFCs was constructed, linking food choice to health end points. It involves scientific validation, generation of relative indices, their translation into a meaningful language based on equivalents to known and understood reference foods, followed by data consolidation and ecological validation. Criteria used to evaluate VFCs were importance, independence, validity, accuracy, robustness, sensitivity, linearity/additivity, relevance, comprehensiveness, acquirability, completeness, meaningfulness, acceptability and safety. The developmental framework and evaluative criteria were applied to glycaemic glucose equivalents (GGE), a VFC representing postprandial glycaemia, and to wheat bran equivalents for faecal bulk (WBE(fb)), a VFC representing faecal bulking efficacy.

RESULTS

VFCs were used to identify foods according to health-related effects that cannot be accurately predicted from food composition data, and were used in a nutrition management system to concurrently show nutrient intake and physiological effects in the same units. The proposed evaluative criteria identified points requiring further research, and showed that lack of integrity-tested VFC data is an immediate challenge.

CONCLUSION

VFCs are a means of communicating relative functional efficacy of foods as a continuous variable, and provide end users with a more accurate and complete view of the health effects of foods than can be provided by health claims or food composition data alone.

Redefining the Glycemic Index for Dietary Management of Postprandial Glycemia

The glycemic index (GI) is a component-referenced index, defined as the effect on blood glucose of glycemic carbohydrate in a food as a percentage of the effect of an equal amount of glucose. GI is not suitable for dietary management of postprandial glycemia because it refers to glycemic carbohydrate, not to food, it is static, i.e., unresponsive to intake, and it is relative in that it can be used appropriately only for equicarbohydrate comparisons. Food values for dietary management, in contrast, must be food-based, intake responsive and sensitive to variations in composition typical of diets. The limitations of GI could be overcome by expanding its definition beyond glycemic carbohydrate, to foods. GI could then be used as a food-referenced index, expressed as glycemic glucose equivalents (GGE)/100 g food, and extrapolated to GGE per common standard measure (CSM) as a value for the glycemic load exerted by familiar food quantities. GI(food) and GGE/CSM would then be expressed as are nutrients in food composition databases, would lie on the same quantity-dependent continuum and could be used with nutrient information to provide a more complete nutritional profile of a food than is provided by nutrients alone. GI would then be a practical adjunct to food composition data, which was its intended role.

Glycaemic glucose equivalent: validation as a predictor of the relative glycaemic effect of foods

BACKGROUND

Glycaemic glucose equivalent (GGE) content of a quantity of a food, based on glycaemic index, food composition and food quantity, is the theoretical weight of glucose that would induce a glycaemic response equivalent to that induced by the given amount of food.

OBJECTIVES

To test whether GGE content predicts glycaemic response to foods differing in glycaemic index, carbohydrate content and intake, over a practical range of carbohydrate intakes.

DESIGN

: Controlled randomised study.

SETTING

Clinical trials unit at the Department of Human Nutrition, University of Otago, Dunedin, New Zealand.

SUBJECTS

In all, 12 volunteers with and 12 without type II diabetes were recruited. All but one subject completed the trial.

METHOD

Yams, biscuits, white rice and porridge were consumed at 10 and 20 GGE doses, and 2-minute noodles at 24 and 48 GGE, following an overnight fast. Incremental areas under the blood glucose response curves (IAUC) over 3 h were calculated for each individual for all foods, and individual glycaemic responsiveness was determined as IAUC/GGE.

RESULTS

Within GGE dose, blood glucose responses to all foods, except rice, were similar. Doubling GGE dose approximately doubled glycaemic response. Relative glycaemic effects were accurately predicted by GGE intake after adjusting for individual glycaemic sensitivity (individual average IAUC/GGE). The accuracy of prediction of relative glycaemic effect from GGE intake was affected little by carbohydrate dose.

CONCLUSION

GGE content predicted glycaemic impact of foods over a practical range of carbohydrate intakes, and may therefore be useful for accurate dietary management of glycaemia in diabetes mellitus. The predictive validity of GGE in mixed meals now needs to be tested.

SPONSORSHIP

Health Research Council of New Zealand contract 00/453.