Wholegrains better than other heart health foods despite high GI
cent lower risk of heart disease and stroke compared with those who
rarely eat wholegrain foods, according to a new review, reports
Dominique Patton.
The findings show that wholegrains have a greater benefit than other foods commonly promoted for heart health. Furthermore, the protective effect of wholegrain foods appears to outweigh any role played by the glycaemic index, said author Dr Peter Clifton from the CSIRO Division of Health Sciences and Nutrition.
The review was commissioned by Go Grains, a nutrition communication programme developed by grain research firm BRI Australia and supported by Australian grain growers and the Commonwealth government. It has been submitted for publication in the European Journal of Clinical Nutrition.
"For example, we see a 10 to 15 per cent reduction in heart disease risk with increased fruit and vegetable intake, and about the same risk reduction with use of the cholesterol-lowering sterol margarine spreads," said Dr Clifton.
"However, the benefit of up to 40 per cent reduction in risk from increasing wholegrain intake to around four servings a day is comparable to the effect we get from the powerful 'statin' drugs doctors now prescribe to lower blood cholesterol levels."
A serving is equivalent to two slices of bread or a cup of cooked porridge.
There are currently 15 million prescriptions written each year in Australia for cholesterol-lowering statin drugs, making them the single largest expenditure item on the Pharmaceutical Benefits Scheme, according to the Productivity Commission.
But researchers still do not know exactly why wholegrains benefit the heart, a factor that may make them more difficult to promote over other heart health foods.
"Most likely it is a combination of factors working together that gives wholegrains a powerful health-promoting effect that is greater than the sum of its individual parts," Dr Clifton said.
Wholegrain foods and legumes contain many 'phytochemicals' - including fibre, resistant starch, antioxidants, phytoestrogens and unsaturated fatty acids - that can help protect the body against diseases such as heart disease and stroke.
They also contain vitamins and minerals (vitamin E, vitamin B6, folate, selenium, copper, iron, zinc and manganese, magnesium) and other components which may act as antioxidants to neutralise damaging free radicals. Wholegrain cereals have actually been found to be equal, or higher, in antioxidants than fruits or vegetables.
These protective compounds appear to override the increased risk of disease associated with the glycaemic index (GI) of wholegrains. GI is a measure of the rate at which carbohydrates are digested.
"If your carbohydrates are wholegrain, they will be protective against heart disease and stroke, even though they have a high GI rating," Dr Clifton said.
"The protective effect of other components in wholegrain foods appears to outweigh any role played by GI, making it clear that the GI rating for food is only one factor to consider when choosing a healthy diet for optimum health and disease prevention," he said.
