GI News Briefs

Vegetarian Women Are Less Likely to Get Fat
Vegetarian and vegan women are less likely to be overweight than meat-eaters even accounting for age, exercise and total kilojoule/calorie intake according to a new study. PK Newby and researchers at Tufts University report their study of 55,459 healthy, middle-aged and older Swedish women who were surveyed about their eating habits, weight and other health and lifestyle factors in the June issue of the American Journal of Clinical Nutrition. They found that 40 per cent of the women who said that they ate meat, poultry, fish, eggs and dairy products as well as plant-based foods were overweight or obese (a BMI of 25 or more) compared with 29 percent of the vegans (no animal products) and semi-vegetarians (dairy foods and fish occasionally). Lacto-vegetarians (dairy products but no meat, poultry, fish or eggs) were the leanest group with 25 percent identified as being overweight or obese. ‘In the present study, energy intakes were higher and fiber intakes were lower as more animal products were included in the diet,’ they said.

‘Notably, all the vegetarian groups had higher intakes of fruit, vegetables and fiber and lower intakes of fat and protein,’ the researchers write. ‘That vegetarians are leaner and have a reduced risk of overweight or obesity despite higher total carbohydrate intake points to the importance of differentiating between types of carbohydrate when selecting diets including weight-loss diets. Current fad diets that emphasize low carbohydrate intakes ignore the fact that whole and refined carbohydates evoke different metabolic responses. This study and others suggest that a high carbohydrate diet may be protective against obesity if the carbohydrates come from fiber-rich foods such as fruit, vegetables and whole grains,’ they said. ‘The advice to consume more plant foods and less animal products may help individuals control their weight.’
—Reported in American Journal of Clinical Nutrition (Vol. 81, No. 6, 1267–1274, June 2005)

Whey to Health
For people with type 2 diabetes, adding whey protein, not any old protein, to a high GI meal with rapidly digested and absorbed carbohydrates can stimulate insulin release and reduce blood glucose spikes after meals according to Dr Mikael Nilsson of Lund University, Sweden writing in the American Journal of Clinical Nutrition. In a small study, Nilsson and his team gave fourteen people with type 2 diabetes a high-GI breakfast (white bread) followed by a high-GI lunch (mashed potatoes with meatballs) both supplemented with either whey protein or ham. They report that when whey was included in the meals, insulin responses were higher, but the rise in blood glucose after the lunch was significantly reduced. In other words, whey protein had the same action as some of the drugs that are frequently added to diabetes therapy. Increasing insulin responses with whey protein ‘might improve glucose homeostasis in type 2 diabetic patients and could possibly postpone the introduction of medical treatment,’ states Nilsson.
—Reported in American Journal of Clinical Nutrition (Vol 82, No. 1, 69–75, July 2005)

No Mixed Message About GI and Mixed Meals
Because most GI testing involves single foods, the question is often asked whether the GI can be applied to mixed meals. ‘The GI concept can be successfully applied to mixed meals that would be consumed in a real life setting,’ report Dr Emma Stevenson, Prof Clyde Williams and Maria Nute in The British Journal of Nutrition. The Sport and Exercise Nutrition Group at Loughborough University investigated the effects of changing the GI of high-carbohydrate mixed meals. Nine recreationally active men took part in two randomised trials. For one they ate a low GI breakfast (GI 44) and lunch (GI 34); and for the other a high GI breakfast (GI 76) and lunch (GI 73). After a three-hour rest they did a 60-minute treadmill run. The researchers found not only that blood glucose and insulin levels were significantly lower after the low GI meals, but also that the utilisation of fat was greater during the 3-hour rest. This could have important implications for weight control.
—Reported in The British Journal of Nutrition (2005; 93, 885–893)

Added Risks
Insulin resistance is an important risk factor for congestive heart failure independent of diabetes, reports Dr Erik Ingelsson in the July issue of the Journal of the American Medical Association. Heart failure's main causes are high blood pressure and coronary artery disease. Smoking, obesity, high blood fat levels, diabetes, valve-related heart disease, and a thicker-than-normal left ventricle in the heart may increase the risk of developing heart failure. The new Swedish study adds insulin resistance to the risk factor list. Ingelsson of the public health and caring sciences departments at Sweden's Uppsala University and his team studied more than 1100 older men for about nine years, on average. The men were all at least 70 when the study started and none had congestive heart failure at the time. During the study, 104 men developed congestive heart failure. They found that insulin resistance predicted the incidence of heart failure independently of other established risk factors. ‘Our observations may indicate that the risk for congestive heart failure is already increased in the long subclinical phase of impaired glucose regulation that precedes clinically manifest diabetes,’ they write.
—Reported in The Journal of the American Medical Association (2005;294:334-341)