Features
Scientists Get the Skinny on Starch
Researchers team up to learn more about resistant starch and to develop new formulations
BY ANDREW VOWLES
It accounts for more than half the calories you eat. It provides dietary fibre to promote intestinal health, including lowering the risk of colorectal cancer. And if a recently funded team of Guelph researchers can make it just right, dietary starch may also help reduce diabetes and coronary heart disease — both rising threats to human health worldwide.
The group expects to begin feeding trials of homegrown resistant starches this year. Ultimately they hope to see their new starch formulations developed from the ground up here at Guelph appear on grocery store shelves in everything from pastas, breads and vegetables to processed foods, sauces and thickeners.
“If we can introduce starches with health benefits, there's a serious prospect of having a positive impact on human health at the population level,” says College of Biological Science dean Michael Emes, a faculty member in the Department of Molecular and Cellular Biology (MCB).
Late last year, he and other Guelph researchers received a three-year strategic grant worth $125,000 a year from the Natural Sciences and Engineering Research Council. The team — consisting of faculty members in MCB, the Department of Human Health and Nutritional Sciences (HHNS) and the Department of Plant Agriculture, as well as a food scientist at Agriculture and Agri-Food Canada (AAFC) and an industry partner — covers research from molecular biology through food science and plant breeding to human health.
Starch is a form of carbohydrate that accounts for up to 70 per cent of caloric intake, from grains to fruits and vegetables. Simple “non-resistant” carbohydrates such as those in corn syrup are easily broken down in the upper part of the gastrointestinal tract. Besides being linked to rising rates of obesity, these high-glycemic-index foods cause blood glucose levels to spike, leading to corresponding rises in insulin and contributing to Type 2 diabetes. More than 2.25 million Canadians are estimated to have diabetes; nine out of 10 have Type 2 diabetes stemming from obesity and physical inactivity.
The Guelph group is investigating resistant starches, which escape digestion in the upper intestine. By entering the blood at a slower, more controlled rate, these carbohydrates help control the body's release of insulin. In addition, resistant starches act as dietary fibre and have been shown to help reduce the risk of colon cancer.
Emes and Prof. Ian Tetlow, MCB, hope to learn more about the complicated process that allows plants to make various forms of starch. Despite the long and widespread use of starches in foods, their biological synthesis — and their varied properties and health effects — remains poorly understood.
“There are a lot of unknowns,” says Tetlow. “We want to understand how starches are put together.”
Plant agriculture professors Liz Lee and Duane Falk are seeking out genes involved in starch synthesis in crop plants bred for Canadian growing conditions. The team also includes Qiang Liu, who studies physical and chemical properties of resistant starch as a scientist with the AAFC food research program in Guelph.
HHNS professor Terry Graham will conduct clinical trials on people fed bagels made with resistant starches. “We'll look at assimilation of food in middle-aged males, who should be concerned about the risk of cardiovascular disease and diabetes,” he says.
He's planning pilot studies for this summer and will ultimately run a long-term feeding study.
Besides affecting consumers' health, this project will benefit Ontario's agri-food industry, says Graham. The team is working with Maple Leaf Foods (Canada) and with collaborators in the United States and Australia.
In a separate project funded by the Ontario Ministry of Agriculture, Food and Rural Affairs, a number of these researchers are working with industry partners on non-food uses of starches in paints, adhesives and industrial coatings.