A new study in the British Medical Journal that reanalyzed old data is challenging the advice to replace saturated fat with vegetable oil:
The original study randomized over 9,400 people to either a diet that replaced saturated fat with corn oil, or to a control group that ate an equivalent amount of saturated fat. People who switched from saturated fat to vegetable oil did lower their cholesterol, but they did not live longer than those who continued to eat saturated fat.
Dr. Christopher Ramsden, lead author of the study, said:
“In fact, participants who had greater reductions in cholesterol had higher, rather than lower, risk of death.”
There was a 22% higher risk of death for every 30 mg/dL reduction in serum cholesterol.
The researchers hypothesized that unsaturated fat contributes to oxidation:
Increasing dietary linoleic acid has been shown to increase oxidized linoleic acid derivatives in a dose dependent manner in many tissues. These oxidized derivatives, along with other non-cholesterol lipid mediators, have been implicated in the pathogenesis of many diseases including coronary heart disease, chronic pain, and steatohepatitis.
The study concluded:
Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes. Findings from the Minnesota Coronary Experiment 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.