The test, known as a glycemic profile, differs to the glycemic index measurement by measuring the blood sugar response for longer, and considering fluctuations in levels. Researchers responsible for developing the new measure believe that the glycemic index concept has shortcomings because it takes its value from the area of the blood sugar response curve.
In contrast, the glycemic profile measuring system, developed by Dr Liza Rosén, a doctor in applied nutrition at Lund University in Sweden, may provide a more accurate picture of the blood glucose response because it also takes the curve's appearance into account.
The flatter the curve the better the glycemic profile, according to Rosén, who’s concept is based on the idea that foods which produce a flatter curve are causing fewer fluctuations in blood sugar level, even if the overall levels of sugar are higher.
“A food with a high glycemic profile [flatter curve] indicates that the energy lasts longer,” said Rosén.
“The absolute best situation is if the product has a low glycemic index and high glycemic profile. This means it's a really good product,” she added.
The emergence of diet programmes and specialist products based on the glycemic index has led to it becoming much more than a scientific measurement, with many health products looking to use low glycemic index values as a marketing tool.
GI shortcomings
“White pasta is one example of a product which in some cases has received a bad reputation because of a high glycemic index. However, white pasta produces just as good a blood glucose response as wholewheat pasta,” said Rosén.
The researchers noted that glycemic index does not take fluctuations in blood sugar into account. This puts foods with a long and fairly low curve at a disadvantage. Not only pasta, but also many rye bread products have this type of curve, they explained.
Rosén explained that the reason why wheat pasta has sometimes been assigned a confusingly high value is that the glycemic index value only considers the entire area under the blood sugar curve.
“White pasta has just as dense a structure as wholewheat pasta and therefore takes a long time to digest. The structure of a food is actually the most important parameter for the glucose response,” said Rosén
“There are a lot of high-fibre bread products in the supermarkets which gives the same blood glucose response as white wheat bread,” she added.
New measure
In order to calculate glycemic profile, glucose levels in the blood are measured for three hours after a meal, in a similar way to that of the glycemic index test.
However Rosén stressed that the glycemic profile measurement is new, and more research is needed to validate its use. For example, she noted that sugary products have to be studied, whilst research is also needed to test whether products with a high glycemic profile also have beneficial effects on blood sugar regulation in the longer term.
Rosén believes this may be the case, however so far it is only a hypothesis.
“We are using the concept and will relate it to other parameters. For example, we suspect that products with a high GP keep you fuller longer, and that products with a high GP could improve blood sugar regulation not only in direct connection with a meal, but also at a later meal”, said Dr Elin Östman, associate professor in applied nutrition.