Butter better for you?
For decades the dietary advice was clear. To reduce the risk of heart disease, eat plant-based polyunsaturated fats rather than animal-based saturated fats. But now a new analysis of an old study from the '70s has thrown into question the medical orthodoxy that margarine is better for your heart than butter.
Source: PM | Duration: 3min 32sec
TIM PALMER: For decades the dietary advice was clear; to reduce the risk of heart disease, eat plant-based polyunsaturated fats rather than animal-based saturated fats.
But now a new analysis of an old study from the '70s has thrown into question the orthodoxy that margarine is better for your heart than butter.
Jennifer Macey reports.
JENNIFER MACEY: In 1966 the Sydney Diet Heart Study began - 458 men, aged between 30 and 59 who had recently had a heart attack or angina were split into two groups.
The control group were given no dietary advice, while the other group were told to eat less saturated fats and increase their polyunsaturated fat intake to 15 per cent of their total energy consumption.
Mark Wahlqvist is an emeritus professor of medicine at Monash University and remembers the study while a medical student in Adelaide.
MARK WAHLQVIST: When the group in Sydney did a clinical trial and found that all caused mortality was actually increased by this kind of dietary change, towards polyunsaturated fatty acids, that sent shockwaves through the medical community, that was in a battle with the dairy industry at the time.
JENNIFER MACEY: Now a new analysis of the controlled randomised trial has found that the increased consumption of omega six polyunsaturated fats also increased the risk of heart disease.
MARK WAHLQVIST: My own view is that people didn't want to know that. The theory about the link between polyunsaturated fatty acids and health outcomes was that it would be favourable, because the cholesterol dropped people didn't want to not believe that the lowering of the cholesterol would have improved coronary mortality.
But it didn't and for years the National Heart Foundation and other expert committees have encouraged the view that it was favourable when it was actually unfavourable.
JENNIFER MACEY: Other nutritionists have pointed out that the margarines in the '60s and '70s contained a lot more trans fats than they do today, which may explain the deaths from heart disease.
Associate Professor Barbara Meyer is from the University of Wollongong and the president of the Nutrition Society of Australia.
BARBARA MEYER: They're very minimal, because now when margarines are made, they are no longer using the hydrogenation process, which then introduced the trans fatty acids, whereas back when this study was conducted, and these margarines offered to these participants, the trans fatty acid content was much higher.
JENNIFER MACEY: However Professor Mark Wahlqvist disagrees.
MARK WAHLQVIST: There's been a change in the structure of the fats to get rid of the trans fatty acids and we don't know yet whether those new fats, so-called trans fatty acid free, have favourable or unfavourable outcomes.
JENNIFER MACEY: What they do agree on is the healthiest form of diet contains a diverse range of different fats; saturated, monounsaturated and omega three and omega six polyunsaturated fats.
BARBARA MEYER: Have a balanced diet, not excessively consume one type of fat over another, but you have a mix of good, healthy fats. Personally I don't see butter as being bad. Now sure, if you sat down and ate a whole 250 gram of butter every day, no I don't recommend that because that is too much saturated fat.
JENNIFER MACEY: Professor Mark Wahlqvist says the advice given in the past has led to many people avoiding eating many healthy foods like eggs for example.
MARK WAHLQVIST: I think it's a serious question, what was going on in the minds of the investigators at the time, what was going on in the formulation of policy, what was going on with the relationship between the food industry and the medical profession and medical science at the time.
TIM PALMER: Monash University Emeritus Professor Mark Wahlqvist.