Another snippet from an interesting article on Dr John Briffa’s website
“Conventional nutritional ‘wisdom’ has it that saturated fat (found in foods such meat, eggs, dairy products, coconut and palm oil) is bad for heart health, while ‘polyunsaturated’ fats (including ‘vegetable’ oils) are good. These concepts emerged decades ago and were mostly based on the impact of these fats on cholesterol levels. There’s a big potential problem here, though: the impact that foods (or anything else) have on cholesterol is not the important thing, it’s the impact that they have on health that really counts.
In 2010, a team of research based in the US reviewed the evidence in which polyunsaturated fats were given to individuals and the effects on cardiovascular disease risk (e.g. heart attacks) were assessed . This review made some attempt to distinguish between the effects of the two main forms of polyunsaturated fat: omega-6 (found in ‘vegetable’ oils such as sunflower oil and safflower oil) and omega-3 (found most abundantly in oily fish such as salmon, trout, mackerel and herring).
This review found that upping omega-6 intakes did not lead to beneficial outcomes for health. However, a mix of omega-3/omega-6 did. In fact, there was a trend (though not statistically significant) for omega-6 supplementation to increase cardiovascular disease risk. The authors concluded: “Advice to specifically increase [omega-6 polyunsaturated fat] intake….is unlikely to provide the intended benefits, and may actually increase the risks of [coronary heart disease] and death.
This evidence was revisited this week by the same team in a study published in the British Medical Journal . The authors added to their previous review with new data that they had extracted from an old study. The study in question, which took place between 1966 and 1973, is known as the ‘Sydney Diet Heart Study’. In this research, about 220 men aged 30-59 were instructed to reduce saturated fat intake and increase polyunsaturated fat intake. The men were supplied with safflower oil and safflower oil-based margarine (both rich in the omega-6 fat known as linoleic acid). A similar number of men got no dietary instruction and acted as controls.
The results of this study were reported in 1978. The men who cut back on saturated fat and boosted their omega-6 intake were found to be at increased risk of death. Effects of the diet on risk of death from cardiovascular disease (including heart disease) were not reported. In this week’s review, the researchers go back to this data to extract this information.
Their analysis confirms the original report of increased risk of death in men on the omega-6-rich diet. Risk of death was elevated by 62 per cent.
However, new findings previously unearthed (or undeclared) were that the men eating the ‘heart-healthy’ diet were at increased risk of dying from cardiovascular disease and heart disease (increases of 70 and 74 per cent respectively).
So, the very diet designed to reduce the risk of heart disease and fatal heart attack was found to have the opposite effect: It killed men, and specifically from heart disease.”
More from the article here