Replacing saturated fats with vegetable oils might lower blood cholesterol, but it wont curb heart disease risk or help you live longer, a study suggests.
The study, published in the British Medical Journal, throws doubt on the widely held belief that vegetable oils rich in linoleic acid are good for heart health.
A team of US researchers, led by Christopher Ramsden at the National Institutes of Health and University of North Carolina, set out to examine the effect of vegetable oils by analysing data from a large trial that took place 45 years ago.
The trial tested whether replacing saturated fat with vegetable oil rich in linoleic acid reduced the risk of coronary heart disease and death by lowering blood cholesterol levels. The control group ate a diet high in saturated fat.
The diet enriched with linoleic acid lowered cholesterol levels, but did not translate to improved survival. In fact, participants who had greater reduction in blood cholesterol had higher, rather than lower, risk of death.
In 2013, the researchers examined unpublished data from a similar trial – the Sydney Diet Heart Study – and found that the risk of death from coronary heart disease was higher in those who replaced saturated fat with vegetable oil rich in linoleic acid.
The findings “add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid,” researchers said.
But, they say, “we should continue to eat (and to advise others to eat) more fish, fruits, vegetables, and whole grains. We should avoid salt, sugar, industrial trans fats, and avoid over eating.”