Why medical imaging could keep diet from losing out to drugs
The balance is tipping from diet and lifestyle to use of drugs and bariatric surgery to combat obesity and chronic disease. However, new medical imaging technologies can help turn the tables.
University of Toronto professor of nutrition David Jenkins, MD, who is most well-known for developing the concept of the glycemic index, gave this year’s Atwater Memorial Lecture co-sponsored by the American Society for Nutrition in Boston on Tuesday at Experimental Biology 2013. In his talk, he warned, “If diet is to be relevant, it should demonstrate the same effectiveness as drugs.”
The problem, he said, faced by diet and lifestyle recommendations has to do with a combination of their inconvenience, impracticality, and unproven results because of lack of well-designed trials demonstrating their effectiveness. The need for an adequate number of subjects that maintained compliance to studies also made them expensive to do. On the other hand, he said, “drugs are a story of success.” They are backed by strong evidence from randomized controlled trials. For example, statins are shown to generally reduce coronary heart disease risk by 20 to 30 percent.
Medical imaging technologies such as magnetic resonance imaging and ultrasound could be useful tools to help demonstrate effectiveness while making research more cost-effective. “Were the father of modern nutrition science here today, he would agree that we must use the very latest technologies,” Dr. Jenkins said referring to Wilbur Atwater. Atwater was the first to pioneer technologies in his time for measuring amounts of food and labor output in units. He was also the U.S. Department of Agriculture’s first chief of nutrition investigations.
Dr. Jenkins said that there is an “untapped potential in foods” for reducing diabetes and coronary heart disease risk. Cohort studies, for example, estimate diet and lifestyle could offer as much as 84 percent risk reduction. He said we needed more data from randomized controlled trials with disease endpoints that demonstrated that diet and food components had as much effectiveness as drugs.
Viscous fibers, slow-release carbohydrates, and acarbose all are food components that have demonstrated success in randomized controlled studies showing benefit. For example, the Study to Prevent Non-Insulin Dependent Diabetes Mellitus (STOP-NIDDM) was a well-designed study demonstrating that arcabose could help in the prevention or delay of type 2 diabetes. Another was the Canadian Trial of Carbohydrates in Diabetes (CCD), published in American Journal of Clinical Nutrition, which was a one-year controlled trial of low glycemic index dietary carbohydrate in type 2 diabetes that found a reduction in C-reactive protein and postprandial glucose.
In the “dietary portfolio” study, Dr. Jenkins used a combination of foods with recognized cholesterol-lowering properties that included viscous fibers (more bile acid losses), soy protein (cholesterol reduction), phytosterols (cholesterol absorption reduction), and almonds and other nuts (multiple mechanisms). The dietary portfolio compared with low-saturated fat dietary advice led to greater reductions in LDL cholesterol after six months.
Dr. Jenkins also praised the design of Look AHEAD (Action for Health in Diabetes) multicenter randomized clinical trial for using different lifestyle interventions to improve glycemic control. In addition, he lauded the design of David Ludwig’s three-way crossover trial comparing the low-glycemic diet, low-carbohydrate diet, and low-fat diet at Children’s Hospital Boston and Brigham and Women’s Hospital.
However, to compete with drugs, Dr. Jenkins said yet more trials were needed and ways to reduce costs were important. There a number of ways, he said, but the potential from medical imaging shouldn’t be ignored. As an example, he showed imaging from intraplaque hemorrhage from Alan Moody’s laboratory at University of Toronto. In addition, he showed organ imaging for detecting liver fibrosis and stiffness from Richard Ehman’s lab at Mayo Clinic. These are examples of technologies that will help put diet and lifestyle back in competition with drugs and surgery.
“Food will either be the solution or the problem,” he said. In the future fight against obesity, diabetes, and other chronic disease, he said, it was important that diet and lifestyle continued to play a role. In ending his lecture, he then recited the well-known quote from Pythagoras:
Men dig their graves with their own teeth and die more by those instruments than by all weapons of their enemies – Pythagoras 570-495 BC