GI Update

Prof Jennie Brand-Miller answers your questions

Prof Jennie Brand-Miller

What’s wrong with today’s diet?’
We didn’t always eat the way we do today. One of the most important ways in which our diet differs from that of our ancestors is the speed of carbohydrate digestion and the resulting effect on our blood glucose and hence every cell in our bodies.

Our hunter-gatherer ancestors would have eaten plenty of animal foods and large amounts of micronutrient-rich plant foods (leaves, berries, nuts, tubers), which would have been gathered every day, ensuring that their overall diet was both naturally low GI and low GL. Their carbohydrate intakes were lower than ours, because the main plant foods they had available were fruits and vegetables rather than cereals like wheat.

Beginning about 10,000 years ago, when we became farmers growing crops rather than hunter-gatherers, our diet changed in many ways. Starch entered the human diet, in a big way, for the first time. Large quantities of harvested cereal grains tipped our diets from being more animal to more plant based. Those plants were what we would now call wholegrain cereals (wheat, rye, barley, oats, corn and rice). The cultivation of legumes (beans), starchy roots and tubers and fruits and berries also contributed to the higher carbohydrate intake of our farmer ancestors.

But food preparation was simple back then: grinding food between stones and cooking it over the heat of an open fire. The result was that although we were eating a higher carbohydrate diet, the carbs were digested and absorbed slowly and the effects on our BGLs minimal. This diet was ideal for hard working farmers because it provided slow-release energy that helped to delay hunger pangs and provided fuel for working muscles long after a meal had been eaten. It was also easy on the insulin-producing cells in the pancreas. As far as we can tell, diabetes was rare.

Over time however, we developed the technology to grind flours more and more finely, and to separate bran completely from white flour. Finally, with the advent of high-speed roller mills in the 19th century, it was possible to produce white flour so fine that it resembled talcum powder in appearance and texture. These fine white flours were – and are – highly prized because they make soft bread and delicious, airy cakes and pastries.

As incomes grew, the foods commonly eaten by our ancestors – slow-release barley, oats and legumes – were cast aside; consumption of fatty meat increased. The composition of the average diet changed again. We began to eat more saturated fat, less fibre and lots more easily digested, highly refined carbohydrates. Then something we didn’t expect happened, too – blood glucose rises after a meal became higher and more prolonged, stimulating the pancreas to produce more insulin. As a result of these developments, we not only experienced higher blood glucose spikes after a meal, but we also experienced greater insulin secretion. We now know that excessively high glucose and insulin levels are among the key factors responsible for diabetes, heart disease and hypertension. And because insulin also influences the way we metabolise foods, it ultimately determines fat storage around the body.

Low GI organic snack bars from Canada
Brother and sister team, Nima and Salma Fotovat, created Taste of Nature to make healthy fruit and nut bars they could be proud of – ‘Nothing artificial, no fillers and no chemicals with names as hard to pronounce as they are to digest’. They are also low GI, certified kosher, certified vegan and dairy and gluten free. From the Toronto home base, they are now sold in 30 countries around the world. Here’s the current range with their GI values and carb content (rounded) per bar:

Low GI Snack bars

For more information, check out their website HERE.

GI testing by an accredited laboratory North America
Dr Alexandra Jenkins
Glycemic Index Laboratories
20 Victoria Street, Suite 300
Toronto, Ontario M5C 298 Canada
Phone +1 416 861 0506

Fiona Atkinson
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit, School of Molecular and Microbial Biosciences
Sydney University
NSW 2006 Australia
Phone + 61 2 9351 6018
Fax: + 61 2 9351 6022

See The New Glucose Revolution on YouTube