1 March 2007

GI News Briefs

Man’s best friend
Keeping a dog can prevent you from becoming ill, help you recover from ill health, and even alert you that you are suffering from certain types of illness according to Dr Deborah Wells from Queens University, Belfast. Writing in the British Journal of Health Psychology she says that although pet owners tend to be healthier in general, it’s dogs that really make a difference. In her overview of published research exploring the relationship between dogs and our health and well-being she found that dog owners had lower blood pressure and cholesterol, fewer minor physical ailments and were less likely to have more serious medical problems. Dogs may also help you recover from illness – even a heart attack. How come? ‘It is possible that dogs can directly promote our well-being by buffering us from stress, one of the major risk factors associated with ill-health. The ownership of a dog can also lead to increases in physical activity and facilitate the development of social contacts, which may enhance both physiological and psychological human health in a more indirect manner,’ she says.
British Journal of Health Psychology Volume 12, Number 1, February 2007 (pp 145-156) and press release


Turning back the clock

Losing weight and exercising are as effective as drugs to prevent or delay type 2 diabetes for people with impaired glucose tolerance (IGT) writes Prof Keith Abrams and colleagues from Leicester University in the British Medical Journal. For their meta-analysis, the team reviewed 17 randomised controlled trials (8084 participants in total) measuring the effects of different interventions including lifestyle changes, diabetes drugs, and anti-obesity drugs. They found that switching to a healthier diet and increasing exercise is as effective as taking prescription drugs to reduce the rate of progression to diabetes in people with IGT. But the lifestyle changes, like the medications, need to be sustained to prevent the onset of diabetes.
BMJ, doi:10.1136/bmj.39063.689375.55 (published 19 January 2007).


15 minutes exercise a day can help ward off diabetes
‘Many people can fight type 2 diabetes through diet and exercise alone,’ says Professor John Thyfault University of Missouri-Columbia. In a new study to be published in the American Journal of Physiology-Cell he reports that acute exercise – as little as 15 minutes a day can have a profound influence on preventing and fighting diabetes. ‘It is important to ward off diabetes early. Exercise has proven to be effective at all levels. At any stage of type 2 diabetes, from an obese child to a person dependent for 20 years on insulin injections, exercise could have a dramatic effect on improving insulin sensitivity.’ His study found that relatively short periods of acute muscle exercise in diabetic rats significantly increased insulin sensitivity in the muscles. Since 80 to 90% of all glucose goes into muscle after a meal, it is reasonable that more active muscles on a day- to-day basis will result in increased insulin sensitivity, Thyfault said. ‘In relation to a person with type 2 diabetes, this would mean that they could lessen their dependence on insulin therapy to control their blood glucose levels or potentially control glucose levels without any drug by just increasing their daily activity levels in addition to the right diet.’
– News release, University of Missouri-Columbia, 9 February 2007


Eat beans, lentils and tofu often
Here at the GI Group we never stop saying that people with diabetes should learn to love lentils and other legumes (pulses). So we welcome Canada’s new Food Guide that recommends people eat beans and other ‘meat alternatives such as lentils and tofu often’ to minimise the amount of saturated fat in their diet – legumes are in the meat and alternatives group in this guide. And minimising saturated fat is very important. Don’t get us wrong. But more than 2 million Canadians have diabetes and this is expected to rise to 3 million by the end of the decade. So it would also have been nice to see the latest guide shout from the treetops that legumes are actually very smart carbs too and are a great alternative to high GI starchy carbs like potatoes. In fact, they reign supreme as low GI foods and eating them often helps you manage your blood glucose levels. GI Group’s Kaye-Foster-Powell says: ‘They are a very important part of a low GI diet, which is why it’s a good idea to include them in your meals at least twice a week. If you are vegetarian, you should eat them in some form most days. They are easy on the budget, versatile, filling, low in calories/kilojoules and nutritious.’

This Roasted Beetroot and White-bean Salad with Balsamic Dressing is from the Low GI Vegetarian Cookbook.

Photo: Ian Hofstetter

Trans fats alternatives now in the firing line
Trans fats (partially hydrogenated oils) have been in the firing line from health professionals in recent years because the evidence clearly shows that they are as harmful for your health as saturated fats raising LDL (bad) cholesterol, lowering HDL (good) cholesterol and contributing to heart disease. New York City restaurants are now banned from using them and many producers of commercial products such as cookies, crackers, pies, doughnuts, and French fries are abandoning them.

A popular alternative for the food industry has been interesterified fats. Interesterification which rearranges the position of individual fatty acids on the fat molecule to generate a stearic acid-rich fat is fast becoming the method of choice to modify fats in foods that require a longer shelf life because this process hardens fat similar to oils containing trans-fatty acids.

But interesterification can alter metabolism in humans reports a new study. In fact these fats may actually be more detrimental to human health than the fats they replace according to Prof K C Hayes and colleagues from Brandeis University with the Malaysian Palm Oil Board and published online in Nutrition & Metabolism. They found that interesterified fats raise blood glucose (20% in a month) and depress insulin. Furthermore, like trans fat, they still adversely depress HDL-cholesterol.

Professor Hayes

The researchers compared trans-rich and interesterified fats with an unmodified saturated fat, palm olein, for their effects on blood fats and blood glucose. Thirty volunteers consumed all three diets in random rotation over four-week diet periods.

‘In this study we discovered that trans fat also has a weak negative influence on blood glucose. The newer replacement for trans, so-called interesterified fat, appears even worse in that regard, raising glucose 20% in a month,’ said Hayes. ‘This is the first human study to examine simultaneously the metabolic effects of the two most common replacement fats for a natural saturated fat widely incorporated in foods. As such, it is somewhat alarming that both modified fats failed to pass the sniff test for metabolic performance relative to palm olein itself,’ noted Dr Kalyana Sundram.
Nutrition & Metabolism 4 (3), 2007, doi: 10.1186/1743-7075-4-3 and Brandeis University news release

Tossing and turning

According to The Gallup Organization, 49% of adults in the United States do not sleep well for at least 5 nights a month, 10–40% have intermittent insomnia, and 10–15% have long-term sleep difficulties. Popular remedies for sleep difficulties include sedatives and tranquillisers, herbal extracts and complimentary medicines, massage and relaxation techniques, regular physical activity, and avoidance of stimulants such as caffeine before sleeping. Both the timing and content of meals are also known to influence sleep. In November 2005, we reported on a small study presented at the 2005 Australasian Sleep Association Conference by University of Sydney Faculty of Health Science PhD student, Ahmad Afaghi. His research found that a high GI meal (jasmine rice) with a low protein content eaten four hours before bedtime cut the time needed to get to sleep compared with a comparable meal made with a low GI rice. It took the people who ate the high GI meal an average of 9 minutes to fall asleep but 17.5 minutes for those who ate the low GI meal. This study, now published in the American Journal of Clinical Nutrition, concludes by saying that: ‘The fact that a simple manipulation of food intake can significantly improve sleep onset lends itself to a possible convenient, inexpensive, and non-invasive therapy for treating difficulty with sleep initiation. Future research that explores the potential benefit of manipulating the GI or GL of meals for persons with sleep disturbance is warranted.
American Journal of Clinical Nutrition 2007;85:426–30


GI Group: ‘It makes sense from a physiological point of view,’ says Prof Jennie Brand-Miller. ‘Glucose levels affect the level of trytophan in the blood and therefore serotonin in the brain.’ However, it’s very early days and needs to be confirmed by larger, long-term studies before recommending people with sleep problems, many of whom may well have diabetes or pre-diabetes, start experimenting with high GI meals.


hermin said...

my point is: why should we use a counter-productive strategy to induce sleep while other safer means (which can probably be even more effective) are there? and for people with sleep difficulties, i think it might be best to treat the "underlying cause" rather than "symptoms", e.g. by stress management, counselling etc. these strategies may as well help with diabetic control and even with emotional eating (eating for comfort/ eating due to pressure or stress).

Anonymous said...

as far as i know, dairy products contain tryptophan - the amino acid which is converted to serotonin - and in so doing they help with sleeping. so dairy products might be a better deal then? they helps induce sleep, while they are also low GI.

Anonymous said...

Most people I know have an intolerance to dairy. Make sure you do not have an intolerance to dairy before drinking milk at bedtime. Drinking milk produces mucous which clogs up the digestive system, resulting in congestion, bloating and a feeling of sluggishness.

hermin said...

i think the reason why those people have dairy intolerance is that their body doesnt make enough enzyme to break down lactose (aka milk sugar). so, the undigested lactose stays and builds up in stomach (without being absorbed) & then a few things happened:

1. the bacteria (bugs) in the digestive system start breaking down the lactose & release lots of gases, leading to bloating

2. the huge amount of lactose draws a lot of water from the digestive system (just think of what happens if we put a jar of sugar in the open, humid air - the sugar will get wet because it draws some water in), and the water just goes out of the body with the lactose - this is how the diarrhea comes about.

Anonymous said...

Basically insomnia is not a well understood condition in its primary form but persons can get insomnia due to stress or emotional upset, or medical conditions etc. I think much more work needs to be done on insomnia. Our study only looked at what the GI did to normal sleepers. You will be pleased to know that we are planning a study now in insomnia.

Regarding Tryptophan (Trp): Tryptophan in food does not seem to travel well across the blood brain barrier unless the ratio of protein to CHO is in the right proportion. There do not seem to be many Trp rich foods which have this ratio or ways we can easily manipulate foods to optimize Trp entry into the brain. Manipulating the GI may be one way but deserves further study. Other amino acids compete with Trp for entry across into the brain, even in milk. If drinking milk was effective we would not have a problem with insomnia in these patients.

Trp was used as a supplement to enhance sleep but due to some rather serious reactions (EMS Syndrome) to using it in pill form it is not legal to sell Trp in most countries including Australia UK and US. Although EMS syndrome was thought to be due to a contaminant in some Trp supplement batches, new evidence suggests it may trigger a kind of allergic reaction in some persons when given as a ‘dose’ in pill form.

Most of the treatments for insomnia are either drug or behaviour related but these are not suitable for all persons and also not always effective. Hence we are looking to see if we can understand the interaction between diet and sleep better and a high GI meal may assist with insomnia, hopefully our new study will shed more light.

At this stage the findings from our study are interesting but require confirmation in subjects with insomnia which is our next step. At the very least we are trying to understand the effects we are seeing and hopefully can develop a strategy which is useful clinically. It may not be suitable for some individuals with diabetes but it may be another therapeutic strategy for some persons without specific contraindication to high GI.

Dr Helen O’Connor