Glycemische Index | mei 2007
"My goal is 'happy, healthy eating' using the GI value as one of the many reasons for food choice"
Professor Jennie Brand-Miller holds a Personal Chair in Human Nutrition in the School of Molecular and Microbial Biosciences at the University of Sydney. Her research focuses on carbohydrates - diet and diabetes/cardiovascular disease, the glycemic index of foods, insulin resistance, human milk oligosaccharides and infant nutrition. She holds a special interest in evolutionary nutrition and the diet of Australian Aborigines. She has published many books and over 200 journal articles. Her books under the series title The New Glucose Revolution and The Low GI DIET are international bestsellers with over 3 million in sales worldwide in 12 languages. She was awarded a Clunies Ross National Science and Technology Award (2003) and was a finalist for Australian of the Year 2006.You are considered to be the “leading lady” on Glycemic Index
(GI). The concept is introduced 25 years ago but the application to chronic
diseases e.g. obesity and diabetes is still controversial today. What’s
your drive?
“Nutrition has been my passion since I was a teenager. I don’t think it would have mattered which area of nutrition I specialised in - it would still give me pleasure and intellectual stimulation. When we began research on the glycemic index in 1982 as a potential tool for the management of diabetes, it was new, controversial and there was still much to learn. I never dreamed we would be applying it to so many different areas, including obesity and cognitive performance.”
In the books you have written you advocate consumption of a low GI diet. Can you explain the rationale?
“Over the last 50 or so years, advances in food technology have brought profound changes to the physical and chemical structure of the carbohydrates in food. Today, we are more likely to be eating carbohydrates that are quickly digested and absorbed. A low GI diet is by definition one in which the carbohydrates have less effect on postprandial glycemia. The rationale is that lower levels of glycemia are desirable because this reduces the risk of chronic disease. Even at high-normal concentrations, glucose is a toxic molecule, increasing oxidative stress, protein glycosylation, LDL oxidation and thrombotic potential. Some cells, including the endothelial cells lining the blood vessels, can’t control the level of uptake of glucose, making them more vulnerable to the effects of fast digestion and absorption.”
Low GI foods are not necessarily ‘healthier’ than high GI foods; there are low GI foods which contain lots of saturated fats, there are high GI foods which supply important (micro)nutrients. What’s your idea on the concept of an optimal mix between high and low GI foods like some scientists suggest?
“True, low GI foods are not necessarily healthier than high GI foods, but this is also true of low fat vs high fat foods, or low energy vs high energy foods. No one factor encompasses all the good attributes in foods. That’s why in Australia, we have taken ‘the bull by the horns’ and developed the not-for-profit GI symbol program that identifies foods that are not only GI tested but nutritious overall. Foods eligible to be part of the GI symbol program must meet the Dietary Guidelines for Australians; National Dietary Guidelines are of course similar the world over. If nutrition professionals take decisive action early, we can avoid the pitfalls that occurred with the low fat phenomenon. We don’t have to go to extremes when it comes to choosing low GI foods, but we DO need to avoid the other end of the spectrum, i.e. that nearly all our carbohydrates have a high GI. This was (and still is) the unfortunate consequence of the emphasis on low fat eating.
The increase of the prevalence of chronic diseases brings forward a renewed interest of nutritional science in GI. What’s your reaction towards European research projects such as Diogenes and Eurostarch in which health effects of (low) GI is researched?
I welcome well-designed, adequately-powered studies being undertaken by nutritionists throughout Europe. I hope it helps to resolve some of the debate surrounding the GI. But I detect a certain level of naivety. Good research can’t be done by guessing which foods are low GI or high GI. Low GI eating isn’t accomplished by undercooking starchy foods or consuming the high fibre version of a cereal product. While the international tables and lists in our books are useful guides, they don’t replace the need for local GI testing of local foods and beverages for the purposes of research. On a recent trip, I was concerned to find that Kellogg’s AllBran® was a completely different product in Denmark and Australia.”
In Europe several initiatives on signposting are taken by both food industry and trade companies to make the healthy choice the easy choice. What makes the GI-symbol program in Australia such a success?
“The GI Symbol program in Australia grew out of the needs expressed by people with diabetes and the local food industry. They wanted a simple ‘signpost’ that flagged those foods that had been reliably GI tested (not guessed or tested in vitro) and were also healthy choices. Throughout the 1990s, Diabetes Australia and the Juvenile Diabetes Research Foundation had received good feedback from their members – low GI eating was helping them manage their blood glucose levels better. Together, these two organisations and the University of Sydney formed a not-for-profit company in 2001, specifically for the purposes of administering a food labelling program. At the heart, is a blue and while GI certified symbol with rules enshrined by law. Strict nutritional criteria consistent with the Dietary Guidelines for Australians must be met. These include ceilings on energy, fat, saturated fat and salt, and where appropriate, minimum levels of fibre. Importantly, we don’t make sugars a criterion because the body doesn’t distinguish between naturally-occurring sugars and refined sugars.”
What’s your ultimate goal with regards to the GI-concept?
“My goal is ‘happy, healthy eating’ using the GI value as one of the many reasons for food choice. I would like to see the majority of carbohydrate foods carry the GI value, particularly if the food or beverage is one that provides large amount of carbohydrate to the diet. Some scientists have become fixated on the goal of lowering glycemia per se, recommending the use of glycemic load (GI x the amount of carbohydrate) in place of the GI, or more complex suggestions. I think this is a mistake because the foods/diets that reduce glycemia most will be devoid of carbohydrate. There are distinct benefits to eating carbohydrates (e.g. they satisfy our instinctual liking for sweetness, they provide fuel for the brain and vigorous exercise), particularly if they are also slowly digested and absorbed. Insulin sensitivity in particular may be promoted by carbohydrates that reach the ileum or large intestine. The presence of slowly digested carbohydrates that reach the lower small intestine is a desirable goal in itself, part of our evolutionary past when carbohydrates were not even cooked, let alone extruded/puffed/popped under high pressures and temperatures. Just as we have learned that the quality of fat is important (not just the amount), the quality of carbohydrate (GI) is relevant to good health. I think there is room for flexibility in the macronutrient ratios (the ratio fat to carbohydrate to protein varied markedly among hunter-gatherers), but quality remains of critical on all counts.”
Want to know more? Please visit:
www.glycemicindex.com
http://www.gisymbol.com.au
“Nutrition has been my passion since I was a teenager. I don’t think it would have mattered which area of nutrition I specialised in - it would still give me pleasure and intellectual stimulation. When we began research on the glycemic index in 1982 as a potential tool for the management of diabetes, it was new, controversial and there was still much to learn. I never dreamed we would be applying it to so many different areas, including obesity and cognitive performance.”
In the books you have written you advocate consumption of a low GI diet. Can you explain the rationale?
“Over the last 50 or so years, advances in food technology have brought profound changes to the physical and chemical structure of the carbohydrates in food. Today, we are more likely to be eating carbohydrates that are quickly digested and absorbed. A low GI diet is by definition one in which the carbohydrates have less effect on postprandial glycemia. The rationale is that lower levels of glycemia are desirable because this reduces the risk of chronic disease. Even at high-normal concentrations, glucose is a toxic molecule, increasing oxidative stress, protein glycosylation, LDL oxidation and thrombotic potential. Some cells, including the endothelial cells lining the blood vessels, can’t control the level of uptake of glucose, making them more vulnerable to the effects of fast digestion and absorption.”
Low GI foods are not necessarily ‘healthier’ than high GI foods; there are low GI foods which contain lots of saturated fats, there are high GI foods which supply important (micro)nutrients. What’s your idea on the concept of an optimal mix between high and low GI foods like some scientists suggest?
“True, low GI foods are not necessarily healthier than high GI foods, but this is also true of low fat vs high fat foods, or low energy vs high energy foods. No one factor encompasses all the good attributes in foods. That’s why in Australia, we have taken ‘the bull by the horns’ and developed the not-for-profit GI symbol program that identifies foods that are not only GI tested but nutritious overall. Foods eligible to be part of the GI symbol program must meet the Dietary Guidelines for Australians; National Dietary Guidelines are of course similar the world over. If nutrition professionals take decisive action early, we can avoid the pitfalls that occurred with the low fat phenomenon. We don’t have to go to extremes when it comes to choosing low GI foods, but we DO need to avoid the other end of the spectrum, i.e. that nearly all our carbohydrates have a high GI. This was (and still is) the unfortunate consequence of the emphasis on low fat eating.
The increase of the prevalence of chronic diseases brings forward a renewed interest of nutritional science in GI. What’s your reaction towards European research projects such as Diogenes and Eurostarch in which health effects of (low) GI is researched?
I welcome well-designed, adequately-powered studies being undertaken by nutritionists throughout Europe. I hope it helps to resolve some of the debate surrounding the GI. But I detect a certain level of naivety. Good research can’t be done by guessing which foods are low GI or high GI. Low GI eating isn’t accomplished by undercooking starchy foods or consuming the high fibre version of a cereal product. While the international tables and lists in our books are useful guides, they don’t replace the need for local GI testing of local foods and beverages for the purposes of research. On a recent trip, I was concerned to find that Kellogg’s AllBran® was a completely different product in Denmark and Australia.”
In Europe several initiatives on signposting are taken by both food industry and trade companies to make the healthy choice the easy choice. What makes the GI-symbol program in Australia such a success?
“The GI Symbol program in Australia grew out of the needs expressed by people with diabetes and the local food industry. They wanted a simple ‘signpost’ that flagged those foods that had been reliably GI tested (not guessed or tested in vitro) and were also healthy choices. Throughout the 1990s, Diabetes Australia and the Juvenile Diabetes Research Foundation had received good feedback from their members – low GI eating was helping them manage their blood glucose levels better. Together, these two organisations and the University of Sydney formed a not-for-profit company in 2001, specifically for the purposes of administering a food labelling program. At the heart, is a blue and while GI certified symbol with rules enshrined by law. Strict nutritional criteria consistent with the Dietary Guidelines for Australians must be met. These include ceilings on energy, fat, saturated fat and salt, and where appropriate, minimum levels of fibre. Importantly, we don’t make sugars a criterion because the body doesn’t distinguish between naturally-occurring sugars and refined sugars.”
What’s your ultimate goal with regards to the GI-concept?
“My goal is ‘happy, healthy eating’ using the GI value as one of the many reasons for food choice. I would like to see the majority of carbohydrate foods carry the GI value, particularly if the food or beverage is one that provides large amount of carbohydrate to the diet. Some scientists have become fixated on the goal of lowering glycemia per se, recommending the use of glycemic load (GI x the amount of carbohydrate) in place of the GI, or more complex suggestions. I think this is a mistake because the foods/diets that reduce glycemia most will be devoid of carbohydrate. There are distinct benefits to eating carbohydrates (e.g. they satisfy our instinctual liking for sweetness, they provide fuel for the brain and vigorous exercise), particularly if they are also slowly digested and absorbed. Insulin sensitivity in particular may be promoted by carbohydrates that reach the ileum or large intestine. The presence of slowly digested carbohydrates that reach the lower small intestine is a desirable goal in itself, part of our evolutionary past when carbohydrates were not even cooked, let alone extruded/puffed/popped under high pressures and temperatures. Just as we have learned that the quality of fat is important (not just the amount), the quality of carbohydrate (GI) is relevant to good health. I think there is room for flexibility in the macronutrient ratios (the ratio fat to carbohydrate to protein varied markedly among hunter-gatherers), but quality remains of critical on all counts.”
Want to know more? Please visit:
www.glycemicindex.com
http://www.gisymbol.com.au
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