1 February 2008

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Anonymous said...

When you tell me to post questions ON the site, I hope you mean here:

With the lastest news on artificial sweeteners being counterproductive to weight loss, I'd like to ask where honey stands in all this. Of course, as a sweetener, it has obvious nutritional benefits compared to white sugar. But how does the sugar and honey compare GI-wise?

GI Group said...

You don't want to believe all you read. Here's a report from Reading Scientific Services Ltd that puts it in perspective:

'Heavily covered in the media this week is a rat study due to be published in Behavioral Neuroscience which appeared to show that rats fed with saccharin put on more weight than those fed sugar. This study has been criticised by other scientists who point to human studies on the efficiency of no/low calorie sweeteners.

Susan Swithers and colleagues from Purdue University, US, fed a group of 27 male Sprague-Dawley rats yoghurt sweetened with either glucose or saccharin. Both groups were given a plentiful supply of this food. Swithers et al. found that the saccharin fed group consumed more food, resulting in increased caloric intake and greater body weight and body fat gain. A blunted thermic response to sweet tasting diets was observed in the saccharin group.

In explanation of their results, the authors suggest that sweet foods may provide a salient orosensory stimulus, which notifies the body of a high calorie intake. The ingestive and digestive reflexes prepare individuals for that intake, but when the sweetness is not accompanied by calories, this reflex system malfunctions.

However, a recent review by Adam Drewnowski and colleagues from the University of Washington, US, suggests that non/low calorie sweeteners can help people reduce their calorie intake. The Washington team evaluated a variety of laboratory, clinical and epidemiological studies on low calorie sweaters, energy density and satiety. Their findings were based on extensive human studies. Results confirmed that use of low calorie sweeteners could help resolve the obesity problem. Weight loss was best achieved by a combination of reduced caloric intake, a less energy dense diet and increased physical activity. In response to the Purdue study, Drewnowski expressed the view that suggesting that low calorie sweeteners actually caused people to gain weight was irresponsible.

Other criticisms of the study by nutrition experts included the small sample size of only 27 rats and the fact that animal studies (including rats) were not necessarily applicable to humans - generally human studies follow animal studies not the other way round. Also, the pre-absorptive phase (cephalic phase) of insulin release (the response to anticipated sugar) is cited as the potential mechanism for over-eating. But previous studies have found that there is no cephalic-phase-insulin-release in humans following the ingestion of aspartame. In addition, a recent study on young rats suggested that any flavour associated with a lack of calories led to overeating in rats.'

As for table sugar and honey. Sugar has a moderate GI value 68 in the 2008 Shopper's Guide to GI Values. As for honey, it depends on the honey. But many pure floral honeys have low GI values. Again, check the Shopper's Guide or the database at www.glycemicindex.com

Anonymous said...

Two different questions for you relating to low GI. The first one - what is the latest research on low GI carbs exercise? My interest lies in those who exercise moderately (around 60 minutes, mod intensity) and those who exercise at a higher intensity. Information on pre and post exercise carbs (as per a fitness course I'm currently undertaking) appears to conflict with general advice on good nutrition, advocating high GI foods.

The second question I have, is on the digestibility of grains. Even though multigrain and whole grain products are promoted for their low GI, some experts say they're not "digested by people as we're not ruminants". Is there any truth in this statement?

These same individuals believe we should only eat grains and dehydrated foods if presoaked for 12 - 24hrs, and won't touch bread or cereal products of any description unless the ingredients are "predigested" or rather, made digestible by deactivating the inhibiting enzyme found within the encapsulating layer of the grain.

I'd welcome your clear insight into both of these questions.

GI Group said...

Thanks for these great questions. We will cover them in detail in April GI News in our Feedback section.