Substituting animal fat with vegetable oil not reducing heart disease risk: Study
13 April 2016
Substituting animal fat in human diet with vegetable oil might not reduce the risk of heart disease, on the contrary it could even boost it, according to a study. The result of the study runs counter to the cornerstone of dietary advice.
The US study found that though the switch from saturated to unsaturated Omega-6 fats lowered blood cholesterol in a trial with nearly 10,000 participants, the expected reduction in heart disease deaths was not seen.
Those with a greater reduction in cholesterol ''had a higher rather than a lower risk of death'', according to the research published by the medical journal BMJ.
Animal fat from meat, butter, cheese and cream had long been seen to be responsible for increasing artery-clogging cholesterol linked to heart disease and stroke.
In 1961, the American Heart Association advised replacement of saturated fats with vegetable oils, a position it still holds even as research had started to challenge that position.
According to the World Health Organisation, saturated fats should comprise less than 10 per cent of total energy intake.
Products such as butter had been replaced by plant-based margarines and cooking oils, while chicken had been preferred over pork.
In the past few years, though, researchers had started taking a closer look at the ''fat is bad'' stance.
Christopher Ramsden, a medical investigator at the National Institutes of Health, and his team studied data from the Minnesota Coronary Experiment, conducted from 1968 to 1973. They found that the trial's results had only been partly published, and data, suggesting the contrary idea that switching animal fats for vegetable fats did not protect the heart, was left out.
The study randomly assigned 2,300 men and women to a diet in which all the oils were replaced with vegetable oils, or a control diet high in animal fats and margarines. Ramsden found that while those who ate more vegetable oils (primarily corn oil) did indeed lower their cholesterol by nearly 14 per cent compared with those who did not, after a year or more, there was no drop in rates of heart disease or dying from heart events. In fact, every 30mg/dL drop in cholesterol, came with a 22 per cent increased risk of death. People who ate animal fats therefore tended to live longer than those who switched to vegetable oils.