Pregnant women may be among the chief beneficiaries of Australia’s leading role in researching and promoting the benefits of a low glycemic index (GI) diet, says visiting Canadian GI pioneer Dr Tom Wolever (pictured).
Dr Wolever was co-author of the original glycemic index study, which 30 years ago suggested that eating foods that supported the maintenance of steady, low levels of blood glucose was the answer to long-term health. He is visiting Sydney to discuss cutting edge research being carried out by the Sydney Medical School.
Among other studies, the school is trialling the effects of a low GI diet on women with gestational diabetes, with a trial group of 700 women. ‘This could have a bigger public health impact than anything else we’re doing,’ says Dr Wolever.
‘Reports from various parts of the world tell us that women are gaining more weight, and gaining more during pregnancy, and that babies are becoming fatter. A fat baby leads to a fat child leads to an obese adult, with all the accompanying health risks — that’s what we think. Treating the mother’s glucose levels reduces all those complications.’
The outcome of the Sydney Medical School trial is not yet known, but other international trials have indicated that:
for women with gestational diabetes the use of drug therapies (such as insulin) to reduce glucose levels reduces birth complications.
for healthy women, consuming a low-GI diet during pregnancy reduces peaks in glucose levels and normalises infant birth weight.
Dr Wolever attributes the major role taken by the Sydney Medical School to Professor Jennie Brand-Miller, author of The New Glucose Revolution titles. ‘Jennie keeps leading the world in many of the clinical trials and demonstrating their effects,’ he says.
The concept of low GI eating remains challenging to many people — although not so many as faced by Dr Wolever and his co-authors 30 years ago.
‘Thirty years ago people thought sugars were evil,’ he says. ‘We suggested that sugars don’t raise blood sugar as much as most of the starchy foods that we eat.
‘And everyone used to think carbohydrates were neutral filler, whereas now we realise that not all carbohydrates are the same. Choosing good quality carbohydrates can have a major impact on health.’
Trials have demonstrated that a low GI diet can improve cholesterol levels, reduce risk of diabetes, heart disease and breast cancer, as well as assisting in long-term weight reduction and increasing sports performance and concentration.
The latter — concentration — is why food companies now herald the benefit of a good breakfast to help your child succeed at school.
‘Studies demonstrate that memory can be improved by what we eat,’ says Dr Wolever. ‘Cognitive ability, memory, and thinking processes get better after eating, because the brain’s fuel source is glucose.’
With a ‘standard’ breakfast, ‘by late morning the brain performs less well than early in the morning, whereas a low GI breakfast increases [the brain’s functioning] just as much but maintains the level for longer.’
Australia was the first country to launch the GI Symbol Program, nearly a decade ago in 2002, to help consumers identify the GI of foods. Foods that carry the symbol are guaranteed to have been properly tested by an accredited laboratory.
Dr Wolever enthuses, ‘The food not only has low GI, but also not too much salt or fat, and not too many calories. If it has [the symbol] then you know it’s a healthy choice.
‘A breakfast cereal may not get the symbol because it includes too much sodium — so then because the company wants the symbol, they reduce the sodium. There’s a whole bunch of spin-offs, and it’s changing the way we eat.
‘The symbol can be considered reliable because it’s not a program run by a company — it’s run by a university and the Diabetes Foundation, by scientists whose only goal is to improve our health. The rest of the world can learn from this.’
To view GI values for over 1000 foods on Australian supermarket shelves go to www.glycemicindex.com
Dr Tom Wolever photo credit: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto