Health Canada Says Glycemic Index is Inconsistent and Misleading
Health researchers from the Canadian government have issued a report that states glycemic index – used by conventional doctors and nutritionists to calculate dietary requirements – would lead to poor food choices “inconsistent with national dietary guidelines.” What is wrong with the glycemic index?
Ironically, the glycemic index was developed in Canada – in 1981 by Dr. David Jenkins and a team of nutritional researchers at the University of Toronto. Their intent was to calculate which foods would be appropriate for diabetics, so they indexed foods by their glycemic response. This is calculated by the two-hour glucose response that food causes.
Each food is indexed after it is tested on at least 10 human subjects, who consume the food after a 12-hour fast. The results are compared to the relative index of glucose.
While the index postulation seems logical, there are many inconsistencies among foods of the same type, depending upon when the food was harvested, how it was cooked or otherwise prepared, how long stored, and even the specific plant variety the food comes from.
Also, the index supposes that every person will respond to the same food the same, and every time that person eats that food they will respond the same way in terms of their glycemic response. These assumptions are all invalid.
Many studies have found that different people react to different foods differently. And even the same people react to the same foods differently depending upon the time, what else they are eating with the food and their physical condition at the time.
One of the most glaring short-comings of the glycemic index is that one’s glycemic response will be different relative the amount of that food eaten. A spoonful of a food will have a completely different glycemic response than a bowlful of that same food.
All of these factors and more create inconsistencies when the glycemic index is utilized.
The Canadian researchers confirmed this as they responded to the question of whether a food’s glycemic index number should be placed on a food label.
The following is their statement:
“Health Canada’s assessment identified 3 areas of concern with respect to GI labeling: 1) the GI measure has poor accuracy and precision for labeling purposes; 2) as a ratio, the GI does not vary in response to the amount of food consumed and the partial replacement of available carbohydrates with unavailable carbohydrates, whereas the glycemic response does; and 3) an unintended focus on the GI for food selection could lead to food choices that are inconsistent with national dietary guidelines. Hence, Health Canada’s current opinion is that the inclusion of the GI value on the label of eligible food products would be misleading and would not add value to nutrition labeling and dietary guidelines in assisting consumers to make healthier food choices.”
Indexing food as to its glycemic response they produce might be a valiant task – one that should not be ignored. And the index does give a general view – a comparative view from one food to the next – of how some foods may be better than others in terms of glycemic response.
But as was pointed out in a recent article that the general advice to diabetics to lay off the fruit was simply wrong – this advice was related to the glycemic index for fruits.
The reality is that nature has provided a complex means of fortifying foods with the nutrition that works best for us. What modern man has done is ignored nature’s systems complexed within whole foods. When we isolate, extract, pulverize and cook the nutrition out of our foods, blending extracted foods into recipes that serve tastebuds but ignore health, we are left with glycemic problems.
An index will not fix that problem. Eating whole foods will.
Written by Case Adams, Naturopath
Aziz A, Dumais L, Barber J. Health Canada’s evaluation of the use of glycemic index claims on food labels. Am J Clin Nutr. 2013 Aug;98(2):269-74.