A study by researchers at the University of Toronto and St Michael's Hospital in Canada found that a diet including foods such as soy proteins, nuts and oat-based fibres cut bad cholesterol by almost 30 per cent - a similar reduction to that achieved by some drug treatments for high cholesterol.
Scientists have known for many years that, individually, soy proteins, nuts, viscous fibres such as those found in oats and barley, and plant sterols (a substance found in vegetable oils and also in leafy green and non-starch vegetables) have the ability to reduce blood cholesterol levels by approximately 4-7 per cent. However, the study, which was the first to examine the effects of these dietary components in combination, found that mixing these components together in a 'combination diet' reduced levels of LDL or 'bad' cholesterol by a dramatic 29 per cent.
The findings are published in the December 2002 issue of Metabolism.
"This opens up the possibility that diet can be used much more widely to lower blood cholesterol and possibly spare some individuals from having to take drugs," said lead author David Jenkins, a professor in University of Toronto's Department of Nutritional Sciences and director of the Clinical Nutrition and Risk Factor Modification Centre at St Michael's Hospital.
Jenkins and his research colleagues measured the cholesterol levels of 13 people who went on the combination diet for a month. The diet followed a seven-day plan using foods available in supermarkets and health food stores, including vegetables such as broccoli, carrots, red peppers, tomato, onions, cauliflower, okra and aubergine; oats, barley and psyllium; vegetable-based margarine; soy protein from products such as soy milk and soy sausages, cold meats and burgers; and almonds, among other ingredients.
A typical day on the diet would have been a breakfast of soy milk, oat bran cereal with chopped fruit and almonds, oatmeal bread, margarine and jam; a lunch of soy meats, oat bran bread, bean soup and fruit; and a stirfry dinner with vegetables, tofu, fruit and almonds.
Jenkins however cautioned that more research was needed before the combination diet could replace the use of statins. "The take home message right now is that there is hope for a drug-free treatment for some people with high cholesterol. For us, the main feature now is to move this forward into longer-term studies," he said.
Jenkins said the researchers also plan to examine the effects of the combination diet after a six-month period and to assess how well people are able to incorporate the diet into their daily lives.
"We see this as being a work in progress and we shall look at new plant components to add to the diet," said Jenkins. He added that although the combination diet was vegetarian, people who follow the principles of the diet but also eat animal proteins might also see a dip in their cholesterol levels. However, he explained: "The closer they follow this diet, the closer they're going to get to a 30 per cent reduction in blood cholesterol levels."
The study received funding from Loblaw Brands, the Almond Board of California and the federal Canadian Research Chair Endowment.