Although the glycemic index (GI) has been around for 20 years, initially intended as a tool for diabetics, it has been embraced by many food manufacturers since 2003 as a way to give a marketing edge to health or diet products - particularly in the aftermath of the low-carb, Atkins phenomenon.
Packaged Facts, a division of MarketResearch.com, has published a new report entitled Low Glycemic Index Products in the US, in which it predicts that sales will experience compound annual growth rate of 45.7 percent through 2011, when they will be worth $1.8bn.
It estimates that 2006 sales have been in the region of $350m. The CAGR from 2003 to 2005 was 55.4 percent, and the continuing growth indicates that it has a long way to go before the trend starts to run out of steam.
GI is perhaps the most consumer-friendly measure of carbohydrates' effect on blood sugar levels. It ranks individual foods according to their impact on blood sugar levels.
But some believe that the index is too basic a measure and advocate that glycemic load may be more helpful, since it also considers the amount eaten and the foods' context as part of the overall diet, thereby quantifying the potential glycemic impact of foods. The glycemic load is calculated by multiplying the glycemic index by the grams of carbohydrates in a serving.
Packaged Facts' report covers all foods bearing labels related to glycemic impact - be they low-glycemic index, 'for glucose management', or explaining how a product impacts on glycemic index or load in marketing materials. It excludes foods that are naturally carbohydrate-free, including unprepared meats, poultry and fish.
Interestingly, while in other sectors of the health and functional foods market beverages lead the pack, in glycemic control they account for only 30 percent - compared to 60 percent for bars. The remainder is made up of cookies, sweets, and other grain-based products.
Packaged Facts expects that the proportion accounted for by the smaller categories is likely to grow - and new categories may enter the glycemic control fray, such as dairy.
One of the drivers behind the trend is undoubtedly Americans' shift towards healthier eating patterns. Awareness of the connection between diet and diabetes is also a factor: according to the American Diabetes Association, 20.8m children and adults in the United States - seven per cent of the population - have diabetes (types I and II). Of these, as many as 6.2m are thought to be unaware that they have the disease.
Another is the availability of products in mainstream stores.
"Low glycemic foods and beverages have made it out of their corners in health food stores to become a widely accepted addition to supermarkets, mass merchandisers and drug stores where they are often double marketed with like foods as well as in the diabetic supplies aisle," said Don Montuori, publisher of Packaged Facts. "This exposure, positive press, and a wealth of new product offerings have helped create a remarkable growth market much akin to what low-carb was."The complex nature of carbohydrates' effect is further underscored by the definitions drawn up by the AACC's (American Association of Cereal Chemists) Glycemic (Net) Carbohydrate Definition Committee and announced in September. While the committee intended to find just one definition to help food manufacturers communicate how the carbohydrate content of a product will affect blood glucose levels, the upshot of heated discussions amongst its members was four.
Available carbohydrate is "carbohydrate that is released from a food in digestion and which is absorbed as monosaccharides and metabolized by the body"; Glycemic response is defined as "the change in blood glucose concentration induced by ingested food"; Glycemic carbohydrate is "carbohydrate in a food which elicits a measurable glycemic response after ingestion"; and glycemic impact is "the weight of glucose that would induce a glycemic response equivalent to that induced by a given amount of food".
Moreover Danisco's Stuart Craig, who is also AACC's international president, said that it is likely the definition will not be the end point, but that the matter will continue to be debated in the future.