high-GI Foods Research Articles

The Effects of Low– and High–Glycemic Index Foods on High-Intensity Intermittent Exercise

The glycemic index (GI) of a preexercise meal may affect substrate utilization and performance during continuous exercise. To examine the effects of low- and high-GI foods on metabolism and performance during high-intensity, intermittent exercise. Seven male athletes participated in three experimental trials (low-GI, high-GI, and fasted control) separated by approximately 7 days. Foods were consumed 3 h before (approximately 1.3 g x kg(-1) carbohydrate) and halfway through (approximately 0.2 g x kg(-1) carbohydrate) 90 min of intermittent treadmill running designed to simulate the activity pattern of soccer. Expired gas was collected during exercise to estimate substrate oxidation. Performance was assessed by the distance covered on five 1-min sprints during the last 15 min of exercise. Respiratory exchange ratio was higher and fat oxidation lower during exercise in the high-GI condition compared with fasting (P < .05). The mean difference in total distance covered on the repeated sprint test between low GI and fasting (247 m; 90% confidence limits +/-352 m) represented an 81% (likely, probable) chance that the low-GI condition improved performance over fasting. The mean difference between high GI and fasted control (223 m; +/- 385 m) represented a 76% (likely, probable) chance of improved performance. There were no differences between low and high GI. When compared with fasting, both low- and high-GI foods consumed 3 h before and halfway through prolonged, high-intensity intermittent exercise improved repeated sprint performance. High-GI foods impaired fat oxidation during exercise but the GI did not appear to influence high-intensity, intermittent exercise performance.

Glycaemic index of four commercially available breads in Malaysia

This study was carried out to determine the blood glucose response and glycaemic index (GI) values of four types of commercially available breads in Malaysia. Twelve healthy volunteers (six men, six women; body mass index, 21.9±1.6 kg/m2; age, 22.9±1.7 years) participated in this study. The breads tested were multi-grains bread (M-Grains), wholemeal bread (WM), wholemeal bread with oatmeal (WM-Oat) and white bread (WB). The subjects were studied on seven different occasions (four tests for the tested breads and three repeated tests of the reference food) after an overnight fast. Capillary blood samples were taken immediately before (0 min) and 15, 30, 45, 60, 90 and 120 min after consumption of the test foods. The blood glucose response was obtained by calculating the incremental area under the curve. The GI values were determined according to the standardized methodology. Our results showed that the M-Grains and WM-Oat could be categorized as intermediate GI while the WM and WB breads were high GI foods, respectively. The GI of M-Grains (56±6.2) and WM-Oat (67±6.9) were significantly lower than the reference food (glucose; GI = 100) (P < 0.05). No significant difference in GI value was seen between the reference food and the GI of WM (85±5.9) and WB (82±6.5) (P > 0.05). Among the tested breads, the GI values of M-Grains and WM-Oat were significantly lower (P < 0.05) than those of WM and WB. There was no relationship between the dietary fibre content of the bread with the incremental area under the curve (r = 0.15, P = 0.15) or their GI values (r = 0.17, P = 0.12), indicating that the GI value of the test breads were unaffected by the fibre content of the breads. The result of this study will provide useful nutritional information for dieticians and the public alike who may prefer low-GI over high-GI foods.

Carbohydrate-rich foods: glycaemic indices and the effect of constituent macronutrients

The glycaemic index (GI) ranks foods according to their acute glycaemic impact and is used in planning meals for patients invoking glycaemic control through diet. Kurakkan (Eleusine coracana) flour roti, rice flour roti, atta flour roti, boiled breadfruit (Artocarpus altilis/Artocarpus communis) and boiled legumes (mungbean, cowpea and chickpea) were categorized as low-GI foods (relative to white bread; Prima Crust Top™), and the corresponding GI (± standard error of the mean) values were 70±8, 69±7, 67±9, 64±7, 57±6, 49±8 and 29±5, respectively. Kurakkan flour pittu and wheat flour roti were classified as medium-GI foods with GI values of 85±6 and 72±6. Hoppers, rice flour pittu, wheat flour pittu and Olu-milk rice (seeds of Nymphaea lotus) were categorized as high-GI foods, and the corresponding GI (± standard error of the mean) values were 120±8, 103±7, 101±8 and 91±8, respectively. The GI values significantly (P<0.01) and negatively correlated with the insoluble dietary fibre (ρ = − 0.780), soluble dietary fibre (ρ = − 0.712) and protein (ρ = − 0.738) contents in grams per 100 g digestible starch containing foods.

Glycaemic index of some commercially available rice and rice products in Great Britain

The glycaemic response to nine types of rice (white basmati, brown basmati, white and brown basmati, easy-cook basmati, basmati and wild rice, long-grain rice, easy-cook long-grain rice, Thai red rice, Thai glutinous rice) and two types of rice vermicelli (Guilin rice vermicelli, Jiangxi rice vermicelli) commercially available in the United Kingdom were compared against a glucose standard in a non-blind, randomized, repeated-measure, crossover design trial. Fourteen healthy subjects (six males, eight females), mean age 38 (standard deviation 16) years and mean body mass index 21.3 (standard deviation 2.3) kg/m2, were recruited for the study. Subjects were served portions of the test foods and a standard food (glucose), on separate occasions, each containing 50 g available carbohydrates. Capillary blood glucose was measured from finger-prick samples in fasted subjects (–5 and 0 min) and at 15, 30, 45, 60, 90 and 120 min after the consumption of each test food. For each type of food, its glycaemic index (GI) was calculated geometrically by expressing the incremental area under the blood glucose curve as a percentage of each subject's average incremental area under the blood glucose curve for the standard food. The 10 foods exhibited a range of GI values from 37 to 92. The study indicated that rice noodles, long-grain rice, easy-cook long-grain rice and white basmati rice were low-GI foods, whilst all of the other foods were medium-GI and high-GI foods. The information presented in this paper may be useful in helping people select low-GI foods from the customary foods consumed by the British and Asian populations.

Glycemic index, postprandial glycemia, and the shape of the curve in healthy subjects: analysis of a database of more than 1000 foods

BackgroundThe glycemic index (GI) characterizes foods by using the incremental area under the glycemic response curve relative to a similar amount of oral glucose. Its ability to differentiate between curves of different shapes, the peak response, and other aspects of the glycemic response is debatable. ObjectiveThe objective was to explore the association between a food’s GI and the shape of the curve in healthy individuals. DesignA large database of 1126 foods tested by standardized GI methodology in 8–12 healthy subjects was analyzed systematically. Each food’s absolute and incremental blood glucose concentrations were compared at individual time points with the GI. The average curve was generated for low-GI (≤55), medium-GI (56–69), and high-GI (≥70) foods within major food categories. ResultsThe GI of individual foods was found to correlate strongly with the incremental and actual peak (Spearman’s correlations of r = 0.76 and r = 0.73, respectively), incremental and actual glucose concentration at 60 min (r = 0.70 and r = 0.66, respectively), and maximum amplitude of glucose excursion (r = 0.68) (all P < 0.001). In contrast, there was only a weak correlation between the food’s GI and the 120-min glucose concentration (incremental r = 0.20, P < 0.001; absolute r = 0.16, P < 0.001). Within food groups, the mean GI, 30- and 60-min glucose concentrations, and maximum amplitude of glucose excursion varied significantly for foods classified as having a low, medium, or high GI (P < 0.001). ConclusionsThe GI provides a good summary of postprandial glycemia. It predicts the peak (or near peak) response, the maximum glucose fluctuation, and other attributes of the response curve.

Glycaemic indices of three Sri Lankan wheat bread varieties and a bread-lentil meal

The glycaemic index (GI) concept ranks individual foods and mixed meals according to the blood glucose response. Low-GI foods with a slow and prolonged glycaemic response are beneficial for diabetic people, and several advantages have been suggested also for non-diabetic individuals. The recent investigations imply an increasing prevalence of diabetes mellitus in Sri Lanka. Thus, the present study was designed primarily to determine the glycaemic indices of some bread varieties in Sri Lanka as bread has become a staple diet among most of the urban people. A second objective was to observe the effects of macronutrients and physicochemical properties of starch on GI. Glycaemic responses were estimated according to FAO/WHO guidelines and both glucose and white bread were used as standards. Non-diabetic individuals aged 22–30 years (n=10) participated in the study. The test meals included white sliced bread, wholemeal bread, ordinary white bread and a mixed meal of wholemeal bread with lentil curry. The GI values (±standard error of the mean) of the meals were 77±6, 77±6, 80±4, 61±6, respectively (with glucose as the standard). The GI values of the bread varieties or the meal did not differ significantly (P >0.05). However, the meal can be categorized as a medium-GI food while the other bread varieties belong to the high-GI food group. A significant negative correlation was obtained with protein (P=0.042) and fat (P=0.039) contents of the food items and GI. Although the GI values of the foods are not significantly different, the inclusion of lentils caused the GI to decrease from a high-GI category to a medium-GI category. According to the present study, a ratio of 1.36 can be used to interconvert the GI values obtained with the two standards.

Is Glycemic Index of Food a Feasible Predictor of Appetite, Hunger, and Satiety?

This review assesses the feasibility of using glycemic index (GI) as a predictor of appetite, hunger and satiety by surveying published human intervention studies. We also discuss the relationship between GI and two appetite/satiety control hormones, leptin and ghrelin. Ingestion of high-GI food increased hunger and lowered satiety in short-term human intervention studies. This effect may be attributed to the rapid decline in blood glucose level following a hyperinsulinemic response caused by a sharp and transient increase in blood glucose level that occurs after the ingestion of high-GI food, which is defined as the glucostatic theory. However, appetite, hunger and satiety after the ingestion of foods with varying GI were inconsistent among long-term human intervention studies. From the few relevant long-term studies available, we selected two recent well-designed examples for analysis, but they failed to elicit clear differences in glycemic and insulinemic responses between high- and low-GI meals (consisting of a combination of different foods or key carbohydrate-rich foods incorporated into habitual diets). One of the reasons that these studies could not predict glycemic response to mixed meals is presumably that the GI of each particular food was not reflected in that of the mixed meals as a whole. Thus, it is difficult to conclude that the GI values of foods or mixed meals are a valid long-term predictor for appetite, hunger and satiety. Both insulin and insulin-mediated glucose uptake and metabolism in adipose tissue affect blood leptin concentration and its diurnal pattern. Circulating ghrelin level is suppressed by carbohydrate-rich meals, presumably via glycemia and insulinemia. Accordingly, low-GI foods may not necessarily increase satiety or suppress appetite and/or hunger because of the lack of insulin-mediated leptin stimulation and ghrelin suppression. However, insulin-mediated leptin stimulation and ghrelin suppression per se is not consistent among studies; thus we were not able to identify a clear relationship among GI, satietogenic leptin, and appetitic ghrelin.

Position of the New Zealand Dietetic Association (Inc): Nutrition for exercise and sport in New Zealand

Position of the New Zealand Dietetic Association (Inc): Nutrition for exercise and sport in New Zealand

Diet and Diabetes Risk in U.S. Black Women and Chinese Women: Glycemic Index and Load

The prevalence of type 2 diabetes has increased substantially in the U.S.; moreover, incidence rates are higher in some ethnic populations than in others (for example, black women are twice as likely as white women to develop the condition). Recent research has focused on modifiable risk factors such as dietary glycemic index (GI; a measure of the rapidity of carbohydrate absorption) and glycemic load (GL; a measure of the total glycemic effect of dietary carbohydrates). Eating high-GI foods triggers a rapid and sustained increase in blood glucose and insulin demand. In two studies, investigators …

Dietary glycemic index, glycemic load, and the risk of breast cancer in an Italian prospective cohort study

Background: Interest in the roles of glycemic index (GI) and glycemic load (GL) in breast cancer etiology has been stimulated by indications that disease risk is linked to insulinemia, sex hormone bioavailability, and insulin-like growth factor 1.Objective: We aimed to determine whether GI and GL were associated with the risk of breast cancer in a cohort of Italian women volunteers from Northern Italy, who enrolled between 1987–1992 in the Hormones and Diet in the Etiology of Breast Tumors Study (ORDET Study).Design: Volunteers completed a semiquantitative food-frequency questionnaire, and anthropometric and lifestyle data were collected. Dietary GI and GL in relation to breast cancer risk were examined in 8926 cohort women, including 289 with breast cancer identified after a mean follow-up of 11.5 y.Results: The relative risk (RR) of breast cancer in the highest (versus lowest) quintiles of GI and GL was 1.57 (95% CI: 1.04, 2.36; P for trend = 0.040) and 2.53 (95% CI: 1.54, 4.16; P for trend = 0.001), respectively. Total carbohydrate intake was not associated with greater breast cancer risk, but high carbohydrate from high-GI foods was. When women were categorized by baseline menopausal status and body mass index (BMI; in kg/m2), the increased risk of dietary GL was confined to those who were premenopausal (RR = 3.89; 95% CI: 1.81, 8.34) and who had normal BMI (ie, <25) (RR = 5.79; 95% CI: 2.60, 12.90) (P for trend = 0.001 for both).Conclusions: A high-GL diet may increase the risk of breast cancer in Italian women. The effect is particularly evident in premenopausal women and those with BMI < 25.

Pinto bean, navy bean, and black-eyed pea consumption do not significantly lower the glycemic response to a high glycemic index treatment in normoglycemic adults

Abstract This study examined the effects of pinto bean, black-eyed pea, and navy bean consumed in 2 amounts, low dose (∼1/2 cup) and high dose (∼1 cup), on the glycemic response to a high glycemic index (GI) treatment (calculated glycemic index = 96) in insulin-sensitive adult men and women. In a randomized, crossover, placebo-controlled design, 12 participants consumed each of the low-dose treatments and 11 participants consumed each of the high-dose treatments in conjunction with a high-GI meal on different mornings, at least 7 days apart. Blood samples collected at time 0 (fasting) and at 30, 60, 90, and 120 minutes posttreatment were analyzed for glucose and insulin. Data were analyzed in 2 groups: low-dose (n = 12) and high-dose (n = 11) treatments. The low-dose treatments were also compared with the high-dose treatments (n = 11). There were no significant time-by-treatment interactions for any of the legume treatments at either the low-dose or high-dose amounts. No significant difference in insulin response, whole-body insulin sensitivity, or homeostasis model assessment for low-dose, high-dose, or low- vs high-dose treatments was found. When provided in the form of a spread, pinto bean, navy bean, or black-eyed pea intake as part of a treatment did not significantly reduce glycemic response to high-GI foods.

Glycaemic index and glycaemic load values of cereal products and weight-management meals available in the UK

There is currently an increased global interest in the published glycaemic index (GI) values of foods. The aim of the present work was to supplement a previous study on the glycaemic response of 140 foods available in the UK by studying a further forty-four foods. One hundred and twenty-two healthy subjects, with a mean age of 32.4 (sd 11.4) years and a mean BMI of 23.6 (sd 3.6) kg/m2, were recruited to the study. Subjects were served equivalent available carbohydrate amounts (50 or 30 g) of test foods (cereal products and weight-management meals) and a standard food (glucose) on separate occasions. Capillary blood glucose was measured from finger-prick samples in fasted subjects (0 min) and at 15, 30, 45, 60, 90 and 120 min after starting to eat each test food. For each test food, the GI value was determined, and the glycaemic load was calculated as the product of the GI and the amount of available carbohydrate in a reference serving size. The GI values of the foods tested ranged from 23 to 83. Of the forty-four foods tested, thirty-three were classified as low-GI, eight as medium-GI and three as high-GI foods. Most GI values of the foods tested compared well with previously published values for similar foods. In summary, this study provides reliable GI and glycaemic load values for a range of foods, further advancing our understanding of the glycaemic response of different foods. The data reported here make an important addition to published GI values.

Glycemic Index–Based Nutritional Education Improves Blood Glucose Control in Japanese Adults

A low–glycemic index (GI) diet is effective in lowering A1C in diabetic patients (1–3). However, most research is from Western countries, where potato and wheat are the main sources of carbohydrates. A GI-based nutrition education program, designed for people who consume white rice (a high-GI food) as the staple, has not yet been studied. We developed a low-GI dietary regimen based on Japanese foods. This study aimed to evaluate whether GI-based nutrition education improves blood glucose control more than a conventional nutrition education in participants with type 2 diabetes or impaired fasting glucose. We conducted a 3-month, randomized, controlled, parallel-group trial. Participant inclusion criteria were as follows: 1 ) fasting plasma glucose (FPG) between 110 and 160 mg/dl or A1C between 5.8 and 8.0% (4) and 2 ) nonusage of any hypoglycemic drugs. All participants attended one group session on conventional nutritional education at baseline. Each participant was then randomly assigned to either GI-based or conventional nutrition education; four individual sessions followed (2nd week and 1st, 2nd, and 3rd month). Conventional nutritional education was based on the Japan Diabetes Society guidelines (4) and focused on lowering total energy intake, mainly …

Development of a glycemic index database for dietary assessment

To address growing research interests and needs, a glycemic index (GI) database was developed for the more than 18,000 foods in the University of Minnesota's dietary data collection software, the Nutrition Data System for Research (NDSR). The primary source of data was current scientific literature with GI selected whenever possible from studies that used the following methodology: North American foods, healthy subjects, and a 2-h glucose response. Two GI numbers were included for all foods, one based on glucose as a reference, and the other, a white bread reference. Assigning indices within a large database also required imputation, because there are relatively few data available from the literature. For database foods that were not a match to foods in the literature, GI was either estimated from similar foods or calculated from available carbohydrate amounts and the GI of ingredients within the food. To evaluate the calculation procedure, GIs were calculated and then compared to known literature values for 102 multi-ingredient foods. A wide range of foods had comparable GIs, while some sweetened dairy products and unsweetened breakfast cereals showed larger GI differences. The GI database provides researchers with a tool to identify low- and high-GI foods and to investigate whether GI or glycemic load (GL) in the diet will influence disease risk factors.

Nutrition on match day

What players should eat on match day is a frequently asked question in sports nutrition. The recommendation from the available evidence is that players should eat a high-carbohydrate meal about 3 h before the match. This may be breakfast when the matches are played around midday, lunch for late afternoon matches, and an early dinner when matches are played late in the evening. The combination of a high-carbohydrate pre-match meal and a sports drink, ingested during the match, results in a greater exercise capacity than a high-carbohydrate meal alone. There is evidence to suggest that there are benefits to a pre-match meal that is composed of low-glycaemic index (GI) carbohydrate foods rather than high-GI foods. A low-GI pre-match meal results in feelings of satiety for longer and produces a more stable blood glucose concentration than after a high-GI meal. There are also some reports of improved endurance capacity after low-GI carbohydrate pre-exercise meals. The physical demands of soccer training and match-play draw heavily on players' carbohydrate stores and so the benefits of good nutritional practices for performance and health should be an essential part of the education of players, coaches, and in particular the parents of young players.

Relations of glycemic index and glycemic load with plasma oxidative stress markers

Recent data suggest that acute hyperglycemia may increase in vivo free radical production. This increased production has been implicated in many disease processes. The objective was to investigate whether a diet with a high glycemic index (GI) or glycemic load (GL) is associated with greater oxidative stress as measured by 2 lipid peroxidation markers, malondialdehyde (MDA) and F2-isoprostanes (IsoPs). Plasma MDA and IsoP concentrations were measured in 292 healthy adults, and dietary GI and GL were assessed by using a validated food-frequency questionnaire. Cross-sectional associations between GI, GL, and the 2 markers were examined by using multiple regression techniques with adjustment for potential confounding variables. Dietary GI was positively associated with both plasma MDA and IsoPs. The mean multivariate-adjusted MDA concentrations increased from 0.55 to 0.73 micromol/L as GI increased from the lowest to the highest quartile (P for trend = 0.02); the corresponding IsoP concentrations increased from 0.034 to 0.040 ng/mL (P for trend = 0.03). GL was positively associated with both MDA and IsoPs, but the linear relation was significant only for MDA. In addition, a marginally significant interaction between overall GI and body mass index (BMI; in kg/m2) for plasma MDA was observed (P = 0.09). The positive association between overall GI and MDA was stronger in those with a BMI < 26.5 than for those with a BMI > or = 26.5. Chronic consumption of high-GI foods may lead to chronically high oxidative stress. A low-GI diet, not a low-carbohydrate diet, appears to be beneficial in reducing oxidative stress.

Glycaemic index and metabolic disease risk

There is growing evidence that the type of carbohydrate consumed is important in relation to metabolic disease risk, and there is currently particular interest in the role of low-glycaemic-index (GI) foods. Observational studies have associated low-GI diets with decreased risk of type 2 diabetes and CHD, and improvements in various metabolic risk factors have been seen in some intervention studies. However, findings have been mixed and inconsistent. There are a number of plausible mechanisms for the effects of these foods on disease risk, which arise from the differing metabolic responses to low- and high-GI foods, with low-GI foods resulting in reductions in hyperglycaemia, hyperinsulinaemia and late postprandial circulating NEFA levels. Low-GI foods may also increase satiety and delay the return of hunger compared with high-GI foods, which could translate into reduced energy intake at later time points. However, the impact of a low-GI diet on body weight is controversial, with many studies confounded by dietary manipulations that differ in aspects other than GI. There is currently much interest in GI from scientists, health professionals and the public, but more research is needed before clear conclusions can be drawn about relationships with metabolic disease risk.

Influence of Glycemic Index/Load on Glycemic Response, Appetite, and Food Intake in Healthy Humans

High glycemic index (GI)/load (GL) diets reportedly enhance appetite and promote positive energy balance. Support for this hypothesis stems largely from acute feeding trials and longer-term studies lacking control over the macronutrient composition and palatability of test foods. This study evaluated the effects of consuming high- and low-GI/GL meals, matched on macronutrient composition and palatability, plasma glucose and insulin, appetite, and food intake. Thirty-nine healthy adults consumed only low- or only high-GI foods ad libitum in the laboratory for 8 days in either high (three foods per meal)- or low (one food per meal)-variety conditions. Glucose and insulin concentrations as well as appetitive sensations were determined before and for 2 h following breakfast and lunch on days 1 and 8. Energy intake was monitored daily. There were no significant differences in plasma glucose or insulin responses, appetitive ratings, or food intake between treatments. These data indicate that the differential glycemic response of foods tested in isolation under fixed time are not preserved under conditions of chronic ad libitum consumption of mixed meals.

The glycemic index of foods influences postprandial insulin-like growth factor–binding protein responses in lean young subjects

Growth in normal and malignant tissues has been linked to hyperinsulinemia and insulin-like growth factors (IGFs). We hypothesized that IGF and IGF-binding protein (IGFBP) responses may be acutely affected by differences in the glycemic index (GI) of foods. We compared the postprandial responses of IGFs and IGFBP to 2 foods of similar macronutrient composition but with greatly different GIs-pearled barley (GI: 25) and instant mashed potato (GI: 85). Ten young lean subjects consumed 50-g carbohydrate portions of the 2 foods or water (extended fast) in random order after an overnight fast. Capillary blood was collected at regular intervals over 4 h for measurement of blood glucose, insulin, and components of the IGF system. Serum IGFBP-1 declined markedly after both meals, but the mean (+/-SEM) change at 4 h was significantly (P < 0.01) more prolonged after the low-GI meal (-55 +/- 20 ng/mL) than after the high-GI meal (-13 +/- 15 ng/mL). Conversely, the change in serum IGFBP-3 concentration at 4 h was significantly (P < 0.05) higher after the low-GI meal (251 +/- 102 ng/mL) than after the high-GI meal (-110 +/- 96 ng/mL); the same pattern was observed at 2 h. Changes in IGFBP-2, free IGF-1, and total IGF-1 responses were minimal and did not differ significantly from those during the 4-h fast. Acute changes in IGFBP-3 after low-GI and high-GI foods may provide a biologic mechanism linking cell multiplication with greater consumption of high-GI carbohydrates.

Effect of glycaemic index on body weight

Dietary carbohydrates result in different postprandial blood glucose and insulin responses, depending on the rate of digestion. The glycaemic index (GI) classification allows for ranking foods according to their effect on the glycaemic response: a high glucose response (high GI) or low glucose response (low GI). There has been great interest in recent years in whether low-GI foods are more satiating and lead to lower body weight than high-GI foods when incorporated into whole diets. Only a few studies with similar macronutrient and fibre intake have assessed the effect of GI on body weight. These studies, ranging from 5 to 16 weeks, have not been able to show improved satiation or lower energy intake or body weight. However, in one study the interesting observation was made that total fat mass was decreased. Further long-term studies using adequate differences in GI are needed to determine whether low-GI diets can beneficially affect long-term body weight homoeost asis in humans. Keywords: energy intake; fat mass; glucose; glycaemic index; insulin; obesity