If you love butter, you’ll be glad to know that the latest review of some old data now shows that replacing the yellow stuff with vegetable oils high in linoleic acid (an omega-6 found, for example, in corn, sunflower, safflower and cottonseed oil) does not reduce your risk of heart disease or overall risk of death – even though it does lower your cholesterol levels.
The re-evaluation of the traditional diet-heart hypothesis published in the British Medical Journal, even suggest that vegetable oils high in linoleic acid (an omega-6) are worse than butter when it comes to preventing heart disease. This casts doubt on the original ‘spreads are better than butter for your heart’ messages that were disseminated when saturated fat was at the height of its demonization. In fact, randomized controlled trials – the gold standard for medical and nutritional research – have never shown that replacing butter with spreads can reduce the risk of death from coronary heart disease or any other cause – despite what we were led to believe.
The largest of these original trials, the Minnesota Coronary Experiment, was carried out between 1968 and 1973, and involved almost 9,500 people living in six state mental hospitals and one state-run nursing home (an ethical nightmare). When these results were finally published in 1989, showing lower cholesterol levels and a neutral effect on mortality, it seems that some important, planned analyses were missing. This omission was recently addressed by modern researchers, using the original data. They found that, as originally reported, the cholesterol levels in those making the switch to a corn oil spread did go down, but the new finding was that there were almost twice as many heart attacks in those who were switched to a spread than in the control group.
Other reviews of old studies agree
Another re-analysis of old data – this time from the Sydney Diet Heart Study – was published in the BMJ in 2013 and this also showed a higher rate of heart disease, and deaths from any medical cause, in those switching from butter to a safflower oil polyunsaturated margarine, compared to controls.
I am so glad I never made the butter to spread switch. I love butter (in moderation) and have never felt guilty for using it, although I do choose to cook with olive oil for the reasons listed here. Everything in moderation, eh?
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