GI News Briefs

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Reducing the Risk of Stroke
Replacing refined carbohydrates with high fibre, low GI carbs may help reduce the risk of hemorrhagic stroke in women according to researchers including Dr Walter Willett from Harvard University and Brigham and Women’s Hospital in the American Journal of Epidemiology. Hemorrhagic stroke (also known as cerebral hemorrhage) occurs when a blood vessel in the brain breaks or ruptures. A high intake of refined carbohydrate may increase the risk of hemorrhagic stroke in women, particularly women who are overweight or obese. These results ‘may have implications for preventing stroke in Asian countries with a higher rate of hemorrhagic stroke and a higher intake of carbohydrate,’ say the authors.
—Reported in the American Journal of Epidemiology 2005; 161:161–169

Is It the GI That Makes the Difference to Weight Control (or Something Else)?
In human studies, it’s hard to control all aspects of a diet. When scientists change the GI of a diet, they often get more fibre and higher food bulk without trying or intending to. Animal studies allow better control of ALL the variables, making the interpretation easier. Harvard researchers report that low GI carbohydrate per se has implications for weight loss, body fat, and risk for diabetes and heart disease. Dorota Pawlak MNutrDiet, PhD and David Ludwig, MD, PhD, director of the obesity program at Children’s Hospital in Boston set up experiments in which rats were fed to gain exactly the same amount of weight. After just 18 weeks, the rats on the high GI diet had 70 percent more body fat and 8 percent less lean muscle mass, compared with the rats on the low GI diet. The high GI group also had significantly higher blood glucose and insulin levels and higher triglyceride levels. When the low GI group was switched to a high GI diet they had greater increases in blood glucose and insulin compared with rats switched from a high to low GI diet.
—Reported in The Lancet (August 28, 2004; vol 364: pp 778–785).

Is Once a Day Enough?
‘It could be possible that only one meal a day needs to include low GI carbs for people to achieve improved glucose tolerance,’ reports the University of Nottingham’s Dr Emma Stevenson in the International Journal of Sport Nutrition and Exercise Metabolism. The study was designed to look at the effect of the GI of the evening meal on responses to a high GI breakfast the next day. The researchers found that when the men ate a low GI dinner their glucose tolerance was improved next day compared with when they ate a high GI evening meal. ‘If people can achieve improved glucose tolerance in the short term simply by eating just one low GI meal a day, rather than eating only low GI carbs this could make it easier for them to stick to a diet,’ said Stevenson.
—Reported in International Journal of Sport Nutrition and Exercise Metabolism, 2005 Vol 15 (3) 308-322. (The Effect of the Glycemic Index of an Evening Meal on the Metabolic Responses to a Standard High Glycemic Index Breakfast and Subsequent Exercise in Men; Emma Stevenson, Clyde Williams, Maria Nute, Peter Swaile, Monica Tsui)