Understanding Glycemic Index and Agave

by GotAgave Expert: Craig Gerbore

During my years with Madhava, I always tried to personally answer as many consumer inquiries as I could. There have been many questions from people who wanted to learn about glycemic index and the importance of agave’s low GI value.

To fully address questions such as these now, we sought an authoritative account of this topic. The IOAA requested assistance from the experts in this field, the Glycemic Index Laboratories in Toronto, Canada.  They were kind enough to respond with the article that follows. It is written in simple, easy to digest (a little food humour), layman’s terms. Hopefully this short article can help you to understand more about the glycemic subject, why it is important and how it relates to agave syrup.

provided by GotAgave Scientific Expert: Glycemic Index Laboratories

What is the glycemic index?

In 1981, scientists at the University of Toronto in Canada published a ground-breaking study demonstrating that different carbohydrate foods have different effects on blood glucose levels.  They introduced the concept of the glycemic index (GI) as a way of ranking carbohydrate foods according to how they affect blood glucose levels.   Foods with a high GI have a large effect on blood glucose levels, raising them sharply and then causing them to drop rapidly.  Meanwhile, foods with a low GI have a more moderate effect on blood glucose levels, causing a smaller and more gradual rise and fall in blood glucose levels.  Low-GI foods help maintain more constant blood glucose levels, which has numerous health benefits.

Since its inception 30 years ago, the glycemic index has become a powerful tool for both clinicians and patients with diabetes in the fight to control blood glucose levels.  It has also become relevant to individuals looking to improve long-term health, wanting to lose weight, and looking to reduce the risks of various health conditions, ranging from heart disease to certain cancers to age-related macular degeneration.

How are foods classified according to the GI?

To help consumers use GI information for everyday food choices, the glycemic index divides carbohydrate foods into 3 categories – low, medium, and high, by ranking them on a scale from 1 to 100, with glucose scoring 100.

Low 55 and under
Medium 56-69
High 70 and above

Since the GI is a physiological measure and therefore subject to some variability, GI value ranges are more important than exact numerical values.  For example, a low GI food with a GI value of 30 is just as good a choice as a low-GI food with a GI value of 20 (assuming they have similar nutritional content).

What foods are best for people to eat?

To improve glucose control and overall health, people are encouraged to consume low-GI foods more often.  Swapping a low-GI food for a high-GI one in the same food group is an easy way to reduce the GI of your overall diet.  For example, eating oatmeal made from large flake oats for breakfast instead of corn flakes is an easy way to go from a high-GI breakfast to a low-GI breakfast.  As well, switching from most varieties of baked white potatoes to sweet potatoes is an easy way to lower the GI of your dinner.

How does the GI relate to health?

Over the past 30 years, research on the GI has exploded, with new implications and connections being discovered as research progresses.  Low-GI diets have been linked to better health, including better diabetes control, reduced risk of heart disease, and reduced occurrences of various cancers, as well as controlling appetite and assisting weight loss.

How is the GI determined?

Since the glycemic index reflects the rate of carbohydrate absorbed in a given food, only foods containing carbohydrate can be tested for their GI.  The glycemic index of a food can only be determined through controlled clinical human trials at a clinical laboratory with GI-testing capabilities.  After consulting with experts on GI testing, ISO, the International Standards Organization, has established a GI determination methodology that is followed by most GI determination laboratories.  According to the ISO methodology, 10 individuals consume a specific amount of a test food following a 12-hour overnight fast.  On a different day, those same individuals also consume a specific amount of reference food (usually glucose) containing the same amount of available carbohydrate, also following a 12-hour overnight fast.  The reference food is tested 2 or 3 times in humans, while the test food is tested once.  This way each subject acts as their own control, removing interpersonal variability from the results.  After consuming the reference food or the test food, the individuals are observed for 2 hours, with blood samples collected every 15-30 minutes.  Using specific laboratory equipment, each blood sample is analyzed for glucose levels.  Statistical calculations are performed comparing blood glucose values and areas under the curve for the test and reference foods for each of the ten subjects.  Using a series of statistical calculations, these values are averaged, resulting in a final glycemic index value that is determined for the test food.

What factors affect the glycemic index of a food?

The glycemic index is a value that can be affected by various factors, including processing, milling, acidity, ripening, and cooking.  The glycemic index reflects how quickly glucose can be released from a food upon eating it.  Foods that have been highly processed will often be easier to digest, resulting in a rapid release of sugar into the bloodstream, and therefore, a high GI.  Meanwhile, foods that have been minimally processed and are more intact are harder to digest and will therefore release sugar more slowly and gradually into the bloodstream, resulting in a lower GI.

How does the GI relate to agave?

In addition to applying to whole foods, the GI applies to ingredients as well.  Some agave syrups have been GI tested and have been determined to be low GI.  Other sweeteners, such as sugar, have medium or high GI values.  Therefore, the low-GI value of agave syrup makes it an appropriate substitute for other sweeteners, when a product with a lower GI is desired.

Atarah Grysman

Manager, Sales and Marketing



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