Managing Glycemic Response

The rapidly rising popularity of glycemic index (GI) has opened the doors to many food industry innovation opportunities.

Dr. Sam Cunningham, Folsom, CA, Dr. Arun Kilara, Chapel Hill, NC, & Mr. Alex Merolli, Pleasanton, CA, Members of Stratecon International Consultants

Everyone is talking about glycemic index (GI), from the news media, to weight loss companies like NutriSystem, which has used GI to re-shape its diet plan, as well as major health organizations. But consumers still don’t know what it means or how to consider it when making food-purchasing decisions.

Many recent articles in industry trade publications, including Nutraceuticals World, have offered detailed information on what constitutes GI, how it is measured, the negative health effects of consuming high glycemic foods and the formulation of low glycemic foods. But as the food industry attempts to gauge the future of GI-based foods, perhaps it is most important to figure out how GI can play a long-term role in changing consumer eating patterns in order to avoid meeting the same fate as low-carb foods.

In a recent Wall Street Journal article (Ellison and Ball, 2006) it was reported that the growth in total food and beverage sales in 2005 increased by 3%. Low fat, reduced fat and fat-free foods increased in sales by just over 2%, low carbohydrate food sales declined precipitously by over 10%, and low glycemic foods grew a whopping 412%! The question remains whether low GI foods are a passing fancy or if it will permanently change America’s eating habits?

GI Defined

GI ranks carbohydrate-containing foods according to their effect on blood sugar levels. A higher GI carbohydrate food raises the blood sugar level almost immediately (up to two hours) after consumption compared to lower GI foods. More specifically, GI is a quantitative method of assessing foods as a function of their postprandial blood glucose response (Jenkins, et al, 1981). The GI of a food is defined as the area under the two-hour blood glucose curve following the ingestion of a fixed portion of carbohydrate (~50 grams). The standard is glucose or white bread.

The average GI value is calculated from data collected in 10 human subjects. Both the standard and the test material must contain an equal amount of carbohydrate. The area of the test food divided by the area of the standard expressed as a percentage is the GI value for that food. The glycemic index separates carbohydrate-containing foods into three general categories: (1) High Glycemic Index Foods (GI 70+), which cause a rapid rise in blood-glucose levels; (2) Intermediate Glycemic Index Foods (GI 55-69) causing a medium rise in blood-glucose; and (3) Low Glycemic Index Foods (GI 54 or less), causing a slower rise in blood-sugar.

The Benefits of a Low-GI Diet

Dr. Francine Kaufmann, professor of Pediatrics at the Keck School of Medicine of the University of Southern California and Head of the Center for Diabetes, Endocrinology and Metabolism at Children’s Hospital Los Angeles, writes in her book, Diabesity: The Obesity-Diabetes Epidemic That Threatens America—And What We Must Do to Stop It, that the human response to ingestion of carbohydrates is an evolutionary relic from Paleolithic man. In short, our bodies are designed to work based on slow digestion and absorption of complex carbohydrates and a gradual release for energy in lean times. Essentially, our bodies have not responded to modern lifestyle and eating habits. Any spikes in blood sugar provoke an insulin response as a survival hormone to capture extra calories and store them as fat.

The current epidemics of obesity and type II diabetes are manifestations of a metabolic pathway, which has not changed to reflect a modern sedentary lifestyle and consumption of readily available calories derived from easily digested foods. David Jenkins, professor of Nutrition at the University of Toronto who pioneered the concept of GI, says that carbohydrates are digested and absorbed in the “first 2 feet of the small intestine rather than in the 22 feet that nature gave us.” The advantages of following a low GI diet are reported to be lower risks of developing cardiovascular and type 2 diabetes related complications (Ebbeling et al., 2005). This sounds promising especially when you consider that about 30% of the U.S. population is obese.

According to a recent critical review, “Several health benefits exist for reducing the rate of carbohydrate absorption by means of a low GI diet. These include: reduced insulin demand, improved blood glucose control and reduced blood lipid levels, all factors that may play important roles in the prevention or management of several chronic Western diseases like diabetes, coronary heart disease and possibly certain cancers” (Augustin, et al., 2002). Further, following a low glycemic diet has been shown to prevent type 2 diabetes and coronary artery disease, including atherosclerosis (Temelkova-Kurktschiev et al., 2000). In animal studies, weight control was also achieved by feeding animals low GI carbohydrates (Pawlak et al., 2004). More details are available in a review article by Jenkins et al., 2002.

The Skinny on GI Foods/Beverages

Low glycemic foods include vegetables, fruits, legumes and wholegrain breads, while high-GI foods include refined grain products such as white bread, potatoes and rice. More than 700 foods have been classified according to their glycemic index (Foster-Powell et al., 2002). However the GI rating obtained depends on a number of factors. For example, cooking methods affect GI. In other words, the more cooking and processing a food is subjected to, the higher the GI. The physical form of a food also has an impact on determined values in the food. The more fiber in the food, the more slowly it is digested and hence the lower the GI. The amylose content of the starch is inversely related to the GI. The type of sugar is important because fructose metabolizes more slowly than glucose. Hence fruits are considered low GI. Dairy generally does fairly well in discussions of GI. Ice cream, sweetened yogurts and flavored milks fall in the moderate GI range due to their added sugar. Nonfat milk, unsweetened yogurts and cheese have GIs in the low range of 0 to 30. Thus, there are a variety of dairy products that can fit nicely into the diets of consumers looking for low GI foods.

The methodology used to determine GI relies on evaluating one ingredient or one food at a time. The problem is, people eat meals comprising of many individual foods, so the composition of the foods eaten and the variety of foods eaten complicate the determination of a GI for that diet. Still, some researchers believe GI is appropriate for mixed foods (Wolever, et al 1985).

There are individual variations between humans and their respective digestive systems. Due to these factors there is considerable debate in the scientific community about the usefulness as well as the meaningfulness of GI.

Potatoes grown in the U.S. have lower GI compared to those grown in the U.K. In a global marketplace for foods and ingredients this may pose label claim challenges. Because this is a complex concept, the question remains as to whether or not consumers can easily comprehend GI numbers as presented or make sense of a simplified logo (as is done in Australia).

To create more understanding and a level playing field for GI products, the Grocery Manufacturers Association (GMA), a Washington, D.C.-based trade organization, chose to petition the FDA in 2004 regarding carbohydrate labeling. In this petition, GMA asked that foods labeled as no carbohydrate, low carbohydrate, good source of carbohydrate and excellent source of carbohydrate be created. FDA has yet to act on this petition.

GMA has taken a position that promotes a healthy lifestyle incorporating a balanced diet, increasing physical activity and building awareness of what is being consumed rather than endorsing any particular diet, such as a low GI diet.

Currently, FDA and USDA have no provisions for GI labeling. And a methodology for determining GI has yet to be addressed. For now, from a regulatory standpoint, there is no pending action to allow or disallow GI claims.

GI Product Messages & Strategies

Predictions of the positive sales impact from low GI products abound. The outlook is driven in part by increasing consumer awareness of the importance of blood sugar management. In 2005, 45% of consumers claimed awareness of GI as a factor important for health; 42% claimed use of low GI foods for blood sugar management. This shift in attitude was widespread with 40-45% awareness across all age groups measured (NMI, 2006). While blood sugar management as a tool for consumer communication appeals to a large mass market, the term “GI” has narrow appeal, mainly to a knowledgeable target market (Sloan Trends, 2005).

Despite enthusiastic predictions that “Low GI” will be a meaningful language to consumers and drive growth in a new product segment, it seems apparent that there are global differences. According to AC Nielsen, the three markets most familiar with GI are Australia (82%), Korea (80%) and New Zealand (76%). The leadership in this market from Australia is likely due to a unique confluence of governmental labeling approvals and innovative food industry marketing to a relatively homogeneous population. The U.S. and European markets, however, continue to lag behind in these communications, as it is thought that consumers might be more receptive to products carrying messages surrounding blood sugar management.

In speaking with selected thought leaders, several themes emerged regarding blood sugar control as a driver for consumer eating choices. There is recognition that GI as a communication tool has limitations. This is because the GI concept is overly technical for most consumers. It also does not directly translate into a meaningful consumer benefit (i.e., How will a low GI food help me? How will a high GI food hurt me?). Perhaps a more useful approach is to reframe the discussion with consumers to focus on more energy/vitality, more effective weight management, digestive health, reduced risk of type II diabetes or steady blood sugar—all of which are directly observed and experienced benefits.

Some nutritionists suggest that in the U.S. emphasis has shifted from dieting to eating a healthy diet. Among the options available for healthy eating is choosing foods with the “right” carbohydrates. In fact, The South Beach Diet is based on this very concept, pushing Kraft Foods to develop an entire line of frozen dinners incorporating the idea of eating right.

Some nutritionists would prefer to simplify the message and inform consumers to select “complex” carbohydrates and avoid “simple” carbohydrates. But do consumers know which carbohydrates are simple and which are complex? For example: Unless you know the GI of pasta al’dente and par-boiled rice, you might not know they are low GI foods. Also beans, vegetables and pasta, and whole grain breads all are slow in glucose absorption and therefore don’t promote rapid onset of insulin production.

Some scientists suggest there is no role for GI in consumer education. They be-lieve in more simple messages like eating more fruits and vegetables, and whole grains. But yet others suggest those messages are not that simple because consumers don’t know which foods offer wholegrain and which don’t. On top of this, there is a lot of confusion surrounding “whole grain with high fiber” claims.

For now, it seems clear that GI can help those knowledgeable consumers that are sufficiently interested and understand the role of various foods, as well as the effects of the cooking of those foods on their postprandial insulin resistance.

Another concern is the apparent inconsistencies in GI among certain foods, which further complicates consumer communications about GI. For instance, why do carrots have a GI of 47 (Willett et al., 2002), while M&Ms have a GI of 33 ( To consumers, these differences are counterintuitive.

To come up with more accurate, understandable communication, one thought leader suggested adapting the GI test methodology to more closely mimic consumer eating patterns or alternatives. For instance, take quantities of carbohydrate normally consumed and use a logical comparison. (e.g. If a bar is to be marketed, how does it compare to other bars or to other snacks?) Comparing a test product to a 50 gram glucose load is better suited for basic research, not product differentiation based on consumer health benefits.

As mentioned previously, the human body has not adapted to the modern diet and lifestyle as evidenced by the epidemics of obesity, diabetes and the related cascade of diseases. According to Saul Katz, president and CEO, Solo GI Nutrition Inc., Edmonton, Alberta, Canada, the solution is to tailor products to more accurately reflect how the human body was designed to function.

Over the years, Mr. Katz believes this problem has been exacerbated by the proliferation of over processed “between-meal” foods that spike blood sugar, as opposed to regular meals where the mixture of foods slows the release of carbohydrates. His solution? Calorie controlled, clinically validated low GI bars that provide for a slow release of glucose into the bloodstream, in turn helping reduce the occurrence of the “spike, crash and crave” response leading to more food consumption.

Rhonda Witwer, business development manager, Nutrition, National Starch Food Innovation, Bridgewater, NJ, prefers the term “glycemic management,” which she says is a more “actionable” term. “Gly-cemic management leads to the question ‘How can I manage my blood sugar levels with diet?’” she said. “Certainly foods with complex carbohydrates and fiber, a widely recognized trend, are more easily produced, marketed and understood by consumers. The long-term future of gly-cemic management, while very beneficial to health in developed economies, requires an adaptation of the test methodology to be more pragmatic and useful for all stakeholders. It also needs to consider the complementary roles of both digestible carbohydrates and fiber.”

In addition to Solo GI’s between-meal solution, it is important to expand consumer awareness of “good vs. bad carbohydrates.” Equally important is the message pertaining to the fact that slowly digested foods help manage spikes in blood sugar levels, and therefore the resultant health issues.

While physical exertion as part of the solution is obvious, the food industry must offer more good tasting snack/
meal products that are slowly digested and compatible with our “Paleolithic” genotype. While this long-term view requires a fundamental shift in dietary regimens, it also allows the food industry to respond as it has in the past with innovative new products.


GI seems to be a very useful tool that can help informed consumers choose the right carbohydrate foods. But other terminology and clear benefit statements are required to drive consumer purchase choices to healthier carbohydrate-based foods. Further, formulation changes are required to help consumers manage their glycemic response, resulting in healthy eating and avoidance of chronic disease, and in turn living a healthier life.

About the authors: Alex Merolli, Dr. Arun Kilara and Dr. Sam Cunningham are members of Stratecon International Consultants. Mr. Merolli is also the co-founder of Life Sciences Alliance, Pleasanton, CA, and can be reached at 925-462-7428; E-mail: [email protected] Dr. Kilara is the founder of Arun Kilara Worldwide, Chapel Hill, NC, and can be reached at 919-968-9322; E-mail: [email protected] Dr. Cunningham is the founder of Cunningham Consulting, and can be reached at 916-804-4525; E-mail: [email protected]

References furnished upon request.
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