News Briefs

Low GI diet reduces metabolic risk factors
Heart disease and type 2 diabetes don’t just happen. The signs may be silent, but the metabolic risk factors such as low levels of good HDL cholesterol, insulin resistance and elevated C-reactive protein (CRP) in the blood will be there. An article in the March issue of American Journal of Clinical Nutrition reports that in the Dutch population that was studied, people who ate a low GI diet rich in dairy foods and fruit but with a low potato and cereal intake had higher levels of HDL ‘good’ cholesterol (the one that clears cholesterol from our arteries and aids its removal from the blood), improved insulin sensitivity, reduced chronic inflammation, and in nonsmokers, fasting glucose. The authors make the point that the 29% decrease they found in CRP was associated with a 10-unit decrease in dietary GI and seems promising for decreasing the risk of metabolic syndrome and cardiovascular disease.

We asked Alan Barclay whose meta-analysis that systematically reviewed the results of 37 prospective cohort studies on the association of dietary GI and chronic disease ‘What’s a realistic GI to aim for in our diet and meals?’ ‘A GI of 45 or less is a reasonable definition of a low GI diet or meal,’ he says. ‘This is because what we now know from numerous observational cohort studies around the world is that the average GI of the diet of people in the lowest quintile (20% of the population) is about 40–50. Similarly, in a recent meta-analysis of 15 experimental studies investigating the role of low GI diets in managing diabetes, the average GI was 45. Since this average GI has been proven to have significant health benefits in people with existing diabetes and in reducing the risk of chronic diseases like heart disease and diabetes, and importantly, people can and do achieve it in real life, we believe a GI of 45 or less is what we all need to be aiming for.’
– American Journal of Clinical Nutrition 2008; 87

There’s always a catch
The balance of protein to carbs in the diet is critical in extending lifespan – in fruit flies – according to a study published in the Proceedings of the National Academy of Sciences. The key to a long life is eating less protein – and not just fewer calories, as was previously thought. But there’s a catch. While cutting protein may help you live longer, it may mean you’ll have fewer children, well, if you’re a fruit fly (Drosophila melanogaster).

‘Animals that eat less live longer, up to a point,’ says Prof. Stephen Simpson of the University of Sydney’s School of Biological Sciences. Using new techniques developed by Simpson and Prof. David Raubenheimer (Auckland University) ‘Our research shows the balance of protein to carbohydrate in the diet is critical.’

‘Flies lived longest when the diet contained a low percentage of protein, and died sooner the more protein they consumed,’ says Professor Simpson. ‘But protein is needed for reproduction – so flies are faced with a conundrum: eat less protein and live longer, or eat more protein and lay more eggs? When offered a choice, flies behaved like nutrient-seeking missiles, unerringly mixing a relatively high protein diet that maximised their lifetime egg production. In other words, flies preferred to achieve maximum evolutionary fitness rather than live as long as possible,’ says Simpson.

– For more information: www.pnas.org/cgi/content/full/0710787105/DC1
– email: stephen.simpson@bio.usyd.edu.au

GI Group: What is Drosophila melanogaster and why bother about it?
We turned to Gerard Manning’s website for answers here. Drosophila melanogaster the little fruit fly about 3 mm long that hovers over the ripe fruit bowl may be a pest in your kitchen but it has proved to be one of the most valuable organisms in biological research. Gerard Manning says: ‘Drosophila has been used as a model organism for research for almost a century. Its importance for human health was recognised by the award of the Nobel Prize in medicine/physiology to Ed Lewis, Christiane Nusslein-Volhard and Eric Wieschaus in 1995. Part of the reason people work on it is historical – so much is already known about it that it is easy to handle and well-understood – and part of it is practical: it’s a small animal, with a short life cycle of just two weeks, and is cheap and easy to keep large numbers.’ If you want to know more about fruit fly research, check out: ceolas.org

Don’t underestimate yourself
Five hundred and two people asked to estimate their waist measurement got it wrong! Men on average underestimated their waist size by 3.1 inches (7.9 cm).

The study, conducted by researchers from Leicester University, looked at 502 people from a variety of ethnic backgrounds. Women in general got their waist measurements wrong by 2.2 inches (5.5 cm). People from white European backgrounds were worse than people from South Asian backgrounds when estimating measurements, with an average 2.9 inches (7.4 cm) error compared to 1.6 inches (4.1cm) for South Asians.

The results of the study were presented to Diabetes UK’s Annual Professional Conference in March. It can take years for symptoms of type 2 diabetes to emerge so simple indicators like waist size (having a large waist is one of the main risk factors) are important signals. ‘Measuring up is a reality check, the first step to recognising that you may not be as well as you feel,’ said Douglas Smallwood, Chief Executive of Diabetes UK. ‘To believe that you are more than three inches slimmer than you are is to ignore a clear warning of a risk of diabetes.’

So the take-home message is measure up. With a tape!

What’s new?
Heart Food
By Veronica Cuskelly and Nicole Senior

Don’t get it, prevent it, is the message in this delicious new cookbook. While you can’t control your age, sex or family background, you can reduce your risk of becoming a heart disease statistic with a healthy heart diet and an active, low-stress lifestyle. Veronica and Nicole’s practical guide to caring for your heart starts in the kitchen. Their new book is packed with family friendly recipes that will be a hit at home, boost your energy, delight your tastebuds and best of all, give your heart the TLC it needs.

Peach, Orange, Carrot and Tahini Juice with Honeydew Melon
Makes 2 serves

Each serving contains ½ a serve of vegetables and 2 serves of fruit

1 cup (250 g/9 oz) sliced canned peaches in natural juice
1 orange (300 g/10½ oz), peeled, quartered, seeds removed
1 carrot (125 g/4½ oz), peeled, chopped roughly
1½ tablespoons (30 g/1 oz) tahini
3 ice cubes
2 wedges(100 g/3½ oz each) honeydew melon

• Place the peaches and juice, orange, carrot, tahini and ice cubes in a blender and blend until smooth – about 20 seconds. Pour into glasses and serve with the melon wedges

Per serving
917 kJ/219 calories; 6 g protein; 9 g fat (includes 1 g sat fat); 27 g carbohydrate ; 8 g fibre

Low GI gluten-free Living Made Easy – North American edition now available
By Kate Marsh, Prof. Jennie Brand-Miller and Philippa Sandall
Published by Da Capo Lifelong Books

More than two million North Americans have celiac disease and need to eat a gluten-free diet – but the absence of grains and the higher fat and sugar content of many gluten-free products can cause some nutrient deficiencies. Having lived with type 1 diabetes since she was ten and celiac disease for the past few years, dietitian and author Kate Marsh knows the difficulties of following a restricted diet. That’s why she teamed up with Prof Jennie Brand-Miller and Philippa Sandall, to put together in a very simple and down-to-earth way everything you need to know about healthy, gluten-free eating including:

• 7 simple dietary guidelines for low GI gluten free eating
• Low GI substitutes for common high GI foods
• GI values of hundreds of popular gluten-free foods.

Plus 70 easy-to-prepare, delicious recipes the whole family will relish.