June 2005 Newsletter

Prof Mark Wahlqvist AO, MD, FRACP

Welcome to the June edition of the HEC newsletter. This edition looks at scientific studies published on: Resistant starch - can it help you lose body fat? Is poultry as healthy as it used to be? Dark chocolate and insulin sensitivity The New Nutrition Healing Food Pyramid Dr Norman Swan's 'Health Minutes' online video clips features the Monash University Longevity Study

Dr Antigone Kouris-Blazos PhD, Grad Dip Diet, BSc (Hons)

WHAT'S NEW IN NUTRITION RESEARCH

Can resistant starch help you burn more body fat?

Historically starch has been thought to be 100% digested to glucose in the small intestine. Research over the last few decades has found that a significant portion (about 10%) is not digested in the small inestine and passes into the large intestine where it is a substrate for bacterial fermentation. This starch is called resistant starch (RS) and many nutritionists think that it should be classified as a component of dietary fibre.
The bacteria in the large intestine produce short chain fatty acids from the RS which may help maintain the health of cells lining the colon (colonocytes) and prevent bowel cancer. These fatty acids are also absorbed into the bloodstream and may play a role in lowering blood cholesterol levels. A new study suggests that RS may also help with weight loss.

A study by Higgins et al, published in October 2004 issue of Nutrition and Metabolism showed that replacing 5.4% of the carbohydrate content of a meal with resistant starch increased fat oxidation by 23% in a sample of 12 study subjects. This increase is apparantly sustained throughout the day, even if only meal contains RS and the increased fat oxidation is sustained if one keeps eating RS on a daily basis. It appears that the RS changes the order in which the body burns food. Usually carbohydrates are used first, but when RS is present, dietary fat is oxidised first into energy before it has a chance to be stored as body fat. This study suggests that including foods high in RS in your daily diet may help with weight management. more....

Is poultry as healthy as it used to be?

In the 1970s the UK Royal College of Physicians and British Cardiac Society recommended eating more poultry because it had little fat. Similar recommendations were made in Australia. In order to meet the rising demand, new methods of intensive poultry production were implemented by poultry farmers. This resulted in quite drastic changes to the body composition of poultry.

A study conducted by Wang et al from the Institute of Brain Chemistry and Human Nutrition, London Metropolitan University looked at changes in body composition of poultry. Meat samples were obtained from several supermarkets and organic food suppliers in the United Kingdom. Historical data was searched from publications and in-house records in the UK. They reported the following:
poultry intake has increased more than 25 times during 1950 to 2000 in the UK
the fat calorie content of broiler chicken has increased to about 4 times greater than that of protein
chicken now has 100 more calories/100g and 4 fold calorie fat to protein ratio as compared to 3 decades ago
omega 3 fatty acid (DHA) has decreased and been replaced by omega 6 fatty acid (linoleic acid) due to cereal feeds.
UK poultry consumption in 50 years has resulted in increased fat calories by up to 41 times.
Eating the same weight of chicken today compared to 30 years ago means you eat 100 more calories and 3-8 times less omega 3 fats.

Dark chocolate helps improve insulin action and lower blood pressure

More good news for chocolate lovers. An Italian study by Lippi et al published in the March 2005 edition of the American Journal of Clinical Nutrition showed that eating 100g dark chocolate (as opposed to white chocolate) for 15 days improved insulin sensitivity and lowered systolic blood pressure in healthy individuals.
If you are trying to lose weight, however, 500g a day of dark chocolate may not help as it will add about 600 calories to your diet!

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