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

Effect of Flour Particle Size on the Glycemic Index of Muffins Made from Whole Sorghum, Whole Corn, Brown Rice, Whole Wheat, or Refined Wheat Flours

The unique properties of sorghum are increasingly being studied for potential health benefits, with one area of emphasis being the impact of sorghum consumption on mitigating type 2 diabetes. The glycemic index (GI) of muffins made from whole grain sorghum flour ground to three different particle sizes (fine, intermediate, coarse) was tested on eight healthy volunteers (ages 18-40) and compared to the glycemic index of whole grain corn, wheat, and rice flours produced using a similar product formula. Sorghum flour ground through a 0.5 mm screen ("fine") had an overall similar particle size to that of the brown rice flour ground using a 0.5 mm screen. The range of GI values was 32 to 56, with only the GI of intermediate milled sorghum flour being lower than that of corn, rice, or wheat (p < 0.05). The lowest glycemic index (32 +/- 17) was found when using sorghum flour with an intermediate particle size (167 +/- 4 μm). Muffins made using brown rice had the next lowest glycemic index at 37 +/- 17. All GI values calculated had large standard deviations, which is common for these types of studies. These results can assist in the product development process to advance the quality of healthy, gluten-free sorghum-based foods for consumers. Further research should investigate if these results can be duplicated and the possible reason for the lower GI of intermediate particle size sorghum flour.

Longer-Term Effects of the Glycaemic Index on Substrate Metabolism and Performance in Endurance Athletes

Nutrition has a decisive influence on athletic performance. However, it is not only the nutrient intake during exercise that is important, but the daily diet must also be adapted to the requirements of physical activity in order to optimally promote training adaptations. The goal of prolonged endurance training is to enhance fat oxidation, to maintain aerobic performance at a higher intensity while sparing limited carbohydrate stores. The targeted modification of macronutrient intake is a common method of influencing substrate metabolism, fuel selection, and performance. However, it is not well established whether the glycaemic index of carbohydrates in our daily diet can improve endurance performance by influencing carbohydrate or fat oxidation during training. Therefore, the aim of the following review is to elucidate the possible influence of the glycaemic index on substrate utilization during exercise and to clarify whether the consumption of a long-term high-carbohydrate diet with different glycaemic indices may have an influence on substrate metabolism and endurance performance.

Short-term effects of sugar-free apricot jam, cocoa powder and dried cranberry cereal bar on glycaemic responses in healthy adults: a randomised clinical trial

High sugar intake has been associated with adverse effects on health, with some types of breakfast being highly linked to overweight and obesity. The aim was to compare the effects of four sugar-free breakfast items, apricot jam with white bread (JWB), white bread (WB), cocoa with fat-free milk (CM), and dried cranberry cereal bar (CB), compared to d-glucose on the glycaemic responses. Using a cross-over design, twelve healthy individuals (25 ± 4 years; BMI 22 ± 2 kg/m²) received isoglucidic test meals (25 g of available carbohydrate) and 25 g glucose reference, in random order. Glycaemic index/load (GI/GL) were calculated, and capillary blood glucose samples were collected at 0–120 min after meal consumption. Subjective appetite was assessed with visual analogue scales. Sugar-free apricot jam and cocoa powder contained traces of available carbohydrates and were consumed along with bread and fat-free milk, respectively. JWB and WB were classified as medium GI, low-to-medium GL; CM as medium GI, low GL; and CB as high GI, low-to-medium GL. Subjective hunger was lower after JWB, fullness was higher after CM and pleasure was higher after CB (P for all < 0⋅05). In conclusion, sugar-free apricot jam with and without WB and cocoa powder with fat-free milk are suitable healthy breakfast options leading to improved glycaemic and subjective appetite responses.

Short-Term Effects of Traditional Greek Meals: Lentils with Lupins, Trahana with Tomato Sauce and Halva with Currants and Dried Figs on Postprandial Glycemic Responses-A Randomized Clinical Trial in Healthy Humans

Low glycemic index (GI) diets have been associated with decreased chronic disease risk. In a randomized, cross-over study we investigated the GI and glycemic response to three traditional Greek mixed meals: Lentils, Trahana, and Halva. Twelve healthy, fasting individuals received isoglucidic test meals (25 g available carbohydrate) and 25 g glucose reference, in random order. GI was calculated and capillary blood glucose (BG) samples were collected at 0-120 min after meal consumption. Subjective appetite ratings were assessed. All three tested meals provided low GI values. Lentils GI was 27 ± 5, Trahana GI was 42 ± 6, and Halva GI was 52 ± 7 on glucose scale. Peak BG values were lowest for Lentils, followed by Trahana and then by Halva (p for all <0.05). Compared to the reference food, BG concentrations were significantly lower for all meals at all time-points (p for all <0.05). Lentils provided lower glucose concentrations at 30 and 45 min compared to Trahana (p for all <0.05) and at 30, 45, and 60 min compared to Halva (p for all <0.05). BG concentrations did not differ between Trahana and Halva at all time points. No differences were observed for fasting BG, time to peak rise for BG, and subjective appetite ratings. In conclusion, all three mixed meals attenuated postprandial glycemic response in comparison to glucose, which may offer advantages to glycemic control.