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Media Release

March 30, 2005

Anti-obesity research exercises the good oil

Taking a daily dose of omega-3 enriched fish oil combined with regular exercise provides significantly greater benefits in the fight against obesity than exercise or fish oil alone, a University of South Australia study shows.

While previous research has shown that modifying diet and participating in regular exercise can reduce cardiovascular risk, few studies have evaluated their combined benefits, according to Professor Peter Howe, Research Fellow in Nutritional Physiology at UniSA’s School of Health Sciences.

Overweight to obese adults at risk of coronary disease participated in a twelve week intervention trial conducted by PhD student, Ms Alison Hill, which examined the effect of omega-3 fish oil taken daily in combination with moderate aerobic exercise three times a week. These people were compared with three groups taking fish oil, sunflower oil, or a combination of sunflower oil and exercise.

As well as being overweight, participants had risk factors for what is known as “metabolic syndrome”, a cluster of symptoms associated with obesity that include elevated blood pressure; high blood triglycerides (a type of fat that predisposes people to heart and arterial disease); and insulin resistance or heightened insulin levels, the precursor to diabetes.
Anti-obesity research exercises the good oil

“The consequences of metabolic syndrome are type two diabetes and cardiovascular disease, which is why we’re so concerned about the looming epidemic of obesity,” Professor Howe said.

“Omega-3 fatty acids in fish oil are polyunsaturated fats that can switch on enzymes specifically involved in oxidising or burning of fat, but they need a driver (in our case, exercise) to increase the metabolic rate in order to lower body fat.

”Our research showed that the fish oil and exercise (FOX) group lost significantly more fat mass than any other group in the study.

“Using Dual Energy X-ray Absorptiometry (DEXA), which gives an image of the body and shows the different densities of tissue, we can distinguish between fat, muscle and bone. The results of the study showed that the total proportion of fat in the body, particularly in the abdominal region, was reduced significantly in the FOX group, but not by fish oil or exercise alone.

“Seeing the impact on body shape and body composition of these participants has been the most exciting outcome of the research,” Professor Howe said.

While undergoing DEXA scans, the heart rate of patients was continuously monitored. While blood pressure tended to decrease with fish oil alone, the tendency was once again greatest in the FOX group. FOX also had a beneficial effect on heart rate variability, triglyceride levels and artery function.

Damaged or diseased blood vessels lose their elasticity, causing circulation problems including elevated blood pressure. Omega-3 protects blood vessel walls by increasing their elasticity and improving endothelial dilation (the ability of the tissue lining arterial walls to relax the artery), enabling increased delivery of nutrients to exercising muscles.

Professor Howe believes there are potential roles for omega-3 and other bioactive nutrients to act as useful adjuncts to drug therapy. He is particularly interested in nutrient drug combinations that not only increase the effectiveness of a drug but reduce the dose required as well as their side effects. One example is non steroidal anti-inflammatory drugs that tend to have as their primary adverse effect irritation and inflammation in the bowel. Omega-3 can counteract the adverse effect in the bowel.

Omega-3 also has the potential to alleviate or minimise inflammation in tissue, with important benefits for sufferers of arthritis and other inflammatory disorders, including psoriasis and possibly asthma.

The research has been undertaken by the Nutritional Physiology Research Group, a joint initiative of UniSA and the University of Adelaide. With expertise in exercise science, UniSA’s Dr Jon Buckley has taken a key role in integrating assessments of physical and cardiovascular performance.

Professor Howe is Director of the recently announced Australian Technology Network (ATN) Centre for Metabolic Fitness - the latest weapon in the battle of the bulge. Comprising researchers from all five ATN Universities (UniSA, Queensland University of Technology, Curtain University of Technology, RMIT University and University of Technology Sydney), this national consortium aims to develop a sustainable solution to the main health and socioeconomic burden of obesity facing Australians.

With a budget of more than $6 million for its first five years, the ATN Centre will work in partnership with the food industry, the CSIRO and other public health agencies.

Professor Howe will coordinate the inputs of more than 30 senior researchers working across the nation in nutrition, exercise science, public health and behavioural research in a unique multidisciplinary collaboration. It will be the first “holistic approach” to public health research, evaluating various combinations of diet and exercise in demonstration trials involving whole communities. A major trial is planned for the Spencer Gulf by the Rural Health School based at UniSA’s Whyalla campus.

Australia has introduced a health claims policy to regulate the messages that the public receives about health benefits of food based on proper scientific substantiation. This will be another very important role for the Centre.

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