Glycemic Index - Variability Among Individuals

2014-08-27 03:17:37 | BioPortfolio


The purpose of this study is to determine the variability in glycemic index determinations for individual foods and food combinations. The study will also evaluate the changes in insulin and free fatty acid levels, plasma lipid and lipoprotein profiles, C-reactive protein-a marker of inflammation and glycosylated hemoglobin- a marker of glucose metabolism during a five-hour period after eating the food or foods. Additionally, supplementary data on variation in oral sensation, habitual food intake, food preferences and genes mediating sensory perception and dietary behaviors (supported by a grant from the Tufts Ross Aging Initiative) will be related to the outcomes on the present study.


The objective of this proposal is to investigate the intra-individual reproducibility (within the same individual, when repeatedly measured) and inter-individual variability (among individuals) of glycemic index (GI) and glycemic load (GL) value determinations for individual foods and food combinations. The specific aims to accomplished this objective are to evaluate reproducibility and variability of GI value determinations in volunteers differing in biologic characteristics - body mass index (BMI), age and gender; assess the effect of macronutrient amounts and combinations, and fiber on variability of GI and GL value determinations; assess the effect of prior meal macronutrient composition ('second meal' effect) on GI value determinations; and relate these data to chronic disease risk factors monitored prior to and during the intervention period. These aims will be accomplished by assessing intra-individual reproducibility and inter-individual variability of repeated GI value determinations for white bread, commonly used as a reference food, relative to glucose, in volunteers selected to represent a range of BMI's (18.5-24.9, 25-29.9, ≥ 30) and ages (18-49.9, 50-85 y), and on the basis of gender, and relate these data to body composition and insulin sensitivity (Phase I). This work will then be extended to address issues related to variability potentially introduced by differences in macronutrient and fiber combinations and loads (Phase II), and finally by 'second meal' effects (Phase III). Prior to each set of food challenges (glucose and test food[s] in random order) volunteers will be characterized on the basis of fasting HbA1c; lipids and lipoproteins; insulin, glucose and C-reactive protein. During the 5-hour challenge (sampling at 0, 15, 30, 45, 60, and every 30 minutes thereafter) volunteers will be monitored for changes in blood glucose, insulin, triglycerides, total, low density lipoprotein and high density lipoprotein cholesterol, and non-esterified fatty acid levels. Additionally, supplementary data on variation in oral sensation, habitual food intake, food preferences and genes mediating sensory perception and dietary behaviors (supported by a grant from the Tufts Ross Aging Initiative) will be related to the outcomes on the present study. The concepts of both GI and GL are in the public domain and it has been suggested that the concepts be incorporated into U.S. federal dietary guidance (U.S. Dietary Guidelines and Dietary References Intakes [DRI]) formulated to promote health and reduce chronic disease risk. This proposal addresses some of the understudied areas for which additional information would be useful in order to determine whether GI and GL should be used to classify foods on an individual basis, as has been suggested, and when formulating dietary guidance for the general population.

Study Design

Allocation: Randomized, Intervention Model: Crossover Assignment, Masking: Double Blind (Investigator, Outcomes Assessor), Primary Purpose: Basic Science




Carbohydrate, Carbohydrate Load, Carbohydrate plus Protein, Carbohydrate plus Fat, Fiber


Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University
United States




Tufts University

Results (where available)

View Results


Published on BioPortfolio: 2014-08-27T03:17:37-0400

Clinical Trials [1207 Associated Clinical Trials listed on BioPortfolio]

Dietary Carbohydrate and Internal Body Fat

This is a 2-year randomized controlled trial to test the effect of dietary carbohydrates, both quality and quantity, on changes in internal body fat mass. Up to 250 women and men with obes...

Lipoprotein Effects of Substituting Beef Protein for Carbohydrate

The purpose of this study is to test whether replacing dietary carbohydrate with protein, using beef as the primarily source of protein, will improve risk factors for cardiovascular diseas...

Fatty Acid Biomarkers of Carbohydrate Intake

The overall aim is to investigate if circulating fatty acids and lipids are influenced by alterations in carbohydrate amount and quality.

Effectiveness of a Low Carbohydrate Diet Versus a High Carbohydrate Diet in Promoting Weight Loss and Improved Health

This study will examine the effects of a low carbohydrate diet versus a high carbohydrate diet on weight loss.

Determining the Ergogenic Effects of Carb10™ Supplementation on Carbohydrate-Rich and Carbohydrate-Restricted Diets

The study will examine the performance and body composition effects of ketogenic vs carbohydrate-based diets, determine the carbohydrate tolerance ("carbohydrate threshold") for active ind...

PubMed Articles [11015 Associated PubMed Articles listed on BioPortfolio]

Cultivation strategy to stimulate high carbohydrate content in Spirulina biomass.

This study focused on verifying if production of Spirulina biomass with high carbohydrate content is stimulated by reduced supply of nitrogen associated to addition of NaHCO or CO at different flow ra...

Plasma cytokine responses to resistance exercise with different nutrient availability on a concurrent exercise day in trained healthy males.

Carbohydrate availability is proposed as a potential regulator of cytokine responses. We aimed to evaluate the effect of a preresistance exercise carbohydrate meal versus fat meal on plasma cytokine r...

Exercise training alters the glycemic response to carbohydrate and is an important consideration when evaluating dietary carbohydrate intake.

Carbohydrates raise insulin concentrations in blood. Exercise decreases the insulin response to carbohydrate infusion and is beneficial in reducing postprandial glucose and insulin concentrations. Thi...

Effect of diurnal variations in the carbohydrate and fat composition of meals on postprandial glycemic response in healthy adults: a novel insight for the second-meal phenomenon.

Meals, particularly carbohydrate intake, determine diurnal blood glucose (BG) excursions. However, the effect of meals with variable carbohydrate content on diurnal BG excursions remains poorly unders...

Effects of light intensity on biomass, carbohydrate and fatty acid compositions of three different mixed consortia from natural ecological water bodies.

This study investigated the effect of light intensity on three various microalga consortia collected from natural ecological water bodies (named A, B and C) towards their fatty acid profiling and frac...

Medical and Biotech [MESH] Definitions

Proteins which contain carbohydrate groups attached covalently to the polypeptide chain. The protein moiety is the predominant group with the carbohydrate making up only a small percentage of the total weight.

The characteristic 3-dimensional shape of a carbohydrate.

Proteins that share the common characteristic of binding to carbohydrates. Some ANTIBODIES and carbohydrate-metabolizing proteins (ENZYMES) also bind to carbohydrates, however they are not considered lectins. PLANT LECTINS are carbohydrate-binding proteins that have been primarily identified by their hemagglutinating activity (HEMAGGLUTININS). However, a variety of lectins occur in animal species where they serve diverse array of functions through specific carbohydrate recognition.

A class of animal lectins that bind to carbohydrate in a calcium-dependent manner. They share a common carbohydrate-binding domain that is structurally distinct from other classes of lectins.

Dysfunctions of CARBOHYDRATE METABOLISM resulting from inborn genetic mutations that are inherited or acquired in utero.

More From BioPortfolio on "Glycemic Index - Variability Among Individuals"

Quick Search


Relevant Topics

Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism ...

Blood is a specialized bodily fluid that delivers necessary substances to the body's cells (in animals) – such as nutrients and oxygen – and transports waste products away from those same cells.  In vertebrates, it is composed of blo...

Searches Linking to this Trial