GI News Briefs

Children’s Growth Rate May Predict Future Problems
Rapid weight gain after two years of age may be creating insulin resistant adults according to a study by Prof David Barker and his colleagues from Oregon Health and Science University (US), and the University of Southampton (UK) reported in the 27 October 2005 issue of the New England Journal of Medicine. ‘Our research shows that it is the rate of weight gain, not the degree of fatness at any one time, which is the main predictor of future problems,’ said Barker. According to Barker, slow early development and under-nutrition in the womb may program a ‘thrifty’ metabolism, which includes insulin resistance that becomes inappropriate with adequate or excess nutrition in childhood.

The researchers looked at detailed height and weight records for 8,760 people who were born in Finland between 1934 and 1944. The group’s growth had been closely tracked from birth to age 11. When the researchers then checked out hospital records, they found that 357 men, and 87 women from the group had been treated for or died from coronary heart disease. On average, those who had a coronary event had been small babies and tiny two-year-olds and thereafter put on weight rapidly to catch up to the average size of their age group by 11. The risk of coronary events was more strongly related to the rate (tempo) of childhood gain in body mass index (BMI) than to the BMI attained at any particular age. The researchers worked closely with Prof Johan Eriksson in Finland whose team examined 2003 of the group alive today, checking their glucose, insulin and cholesterol levels. The smallest babies and 2-year-olds tended to have higher blood pressure and levels of fasting blood sugar and insulin as adults.

The researchers say that the findings are likely a result of the impact of early weight gain on long-term insulin processing. Barker thinks the risk from this change in size is connected to body composition. ‘All children gain muscle as they grow. But a child’s ratio of muscle to body weight is largely set by age two, barring serious exercise,’ he said. ‘So small children who catch up to average weight adding fat, ending up with a higher fat-to-muscle ratio that predisposes to diabetes and heart vessel disease.’
—New England Journal of Medicine 2005;353:1802–9

You Can Enjoy a Pre-dinner Drink
Many studies have linked moderate alcohol consumption (that’s 1, 2 or 3 drinks a day, depending on your gender and weight) with reduced risk of cardiovascular disease and type 2 diabetes. The question is ‘why’? Clinical trials have shown that alcoholic beverages, irrespective of type, increase your HDL or ‘good’ cholesterol levels as well as improve insulin sensitivity. There may be other mechanisms operating according to a paper presented at Nutrition Society of Australia. Researchers Kaniz Fatima and Chris Middlemiss from the School of Human Nutrition at the University of Sydney found that a pre-dinner drink (beer, wine and gin were used in the study) tends to reduce the blood-sugar response to the next meal. In three separate studies, 38 healthy, young, lean people drank two standard glasses of beer, or wine, or gin and tonic or water about an hour before eating then their blood glucose and insulin levels were measured. The researchers found the alcohol seemed to produce a ‘priming’ effect, kicking off the metabolism process and keeping blood-sugar levels low. ‘Realistic amounts of beer, wine or gin reduce postprandial glycemia but not insulinemia’ say the researchers in their conclusion. ‘This effect applies to drinks consumed alone in lieu of a starchy snack, or simultaneously with a meal, or as a pre-dinner cocktail.’
—Nutrition Society of Australia, November 2005

Potato Salad Anyone?
Boiled, mashed, steamed or fried, just about everybody loves potatoes. Unfortunately, a low GI variety of potato is hard to come by. The good news for potato lovers is that a potato salad made the day before with a vinegary vinaigrette dressing and kept in the fridge can lower the GI. Margareta Leeman and her colleagues at the University of Lund in Sweden in their report in the European Journal of Clinical Nutrition say that compared with freshly boiled potatoes, the GI of boiled cold-stored potatoes with vinaigrette, were reduced by 43 per cent. For the study, 13 healthy volunteers tucked into freshly boiled potatoes; boiled and cold-stored potatoes (8o°C for 24 hours); and boiled and cold-stored potatoes tossed in a vinaigrette dressing. (The dressing was made with 8 grams of olive oil and 28 grams of white vinegar at 6 per cent acetic acid.) All meals contained 50 grams available carbohydrate and were served at breakfast time after an overnight fast. Cold storage increased the potatoes’ resistant starch content from 3.3 to 5.2 per cent.
—European Journal of Clinical Nutrition, (2005) 59, 1266–1271

A Matter of Endurance
Athletes commonly consume high carb foods or drinks after exercise to replace their muscle glycogen stores as rapidly as possible—especially when they are training and competing on consecutive days. Dr Emma Stevenson and the Sport and Exercise Nutrition Research Group at Loughborough University compared the effects of high and low GI carbohydrate recovery diets in the 24 hours following prolonged heavy exercise. Nine active male athletes took part in two trials. On the first day they ran for 90 minutes at 70% VO2 max and then ate either a high or low GI recovery meal which provided them with 8 grams of carbohydrate per body mass. The next day after an overnight fast they ran to exhaustion. ‘The results of the present study show the consumption of a low GI diet in the 24 hours following prolonged running increased endurance capacity the next day beyond that which was achieved following the consumption of a high GI carbohydrate recovery diet. A higher rate of fat oxidation throughout the run to exhaustion in the low GI trial is a possible explanation for this increased endurance capacity,’ concludes the research team. Stevenson told GI News: ‘When the recovery period between exercise sessions is a day or more, low GI carbs may be just as effective for optimal recovery as high GI carbs and they will also promote the burning of fat as fuel as you exercise.’
— International Journal of Sport Nutrition and Exercise Metabolism, 2005, 15, 333–349

Vegans Lost Weight without Feeling Hungry
A high carb, low fat, vegan diet with no limit on portion size proved as effective as a 1200 cal a day reduced energy diet according to a study reported in the September issue of The American Journal of Medicine. Dr Neal Barnard, President of the Physicians Committee for Responsible Medicine with colleagues from Georgetown University Hospital and George Washington University conducted the study involving 59 overweight, postmenopausal women. ‘The study participants enjoyed unlimited servings of fruit, vegetables, whole grains and other healthful foods that enabled them to lose weight without ever feeling hungry,’ said Barnard. Animal products, added oils, avocados, nuts, nut butters and seeds were proscribed. The control group’s diet was based on (US) National Cholesterol Program guidelines. During the 14-week study, there were no limits on portion sizes and the women were asked not to alter their normal exercise patterns. They were given detailed nutrition guidelines for preparing their own meals or eating out and they attended weekly hour-long meetings with a physician and dietitian that included cooking instruction. ‘The low-fat, vegan diet was associated with significant weight reduction along with improvements in measure of glucose tolerance and insulin sensitivity … longer-term trials will determine the sustainability of the intervention diet’ concludes the report. For a copy of the paper, contact jeannem@pcrm.org
—The American Journal of Medicine

GI Group says: Competition is fierce in the race between the advocates of high protein versus vegetarian diets for weight loss. It’s clear that there’s more than one good diet. Humans can derive food energy in multiple ways and still be healthy specimens. The trick is to find a healthy diet that you can live with over the long term. For some, that will be high in lean animal proteins, for others it will be high in plant foods. Either way, low GI carbs are the way to go.