For years, we've been told that butter is bad for us and should be replaced with healthier alternatives, such as vegetable oil.
But new research suggests that, actually, butter might not be so bad after all.
A team of researchers said there has been an "over-estimation of the benefits of replacing saturated fat with vegetable oils".
After analysing various clinical trials, they discovered that those who followed a diet rich in vegetable oil generally had lower cholesterol levels.
However they also had a higher rate of death than those who consumed saturated fats, found in butter and margarine.
Despite the findings, health officials have warned that too many saturated fats can increase cholesterol and result in heart disease.
A study by researchers at the National Institutes of Health in Maryland analysed several trials, one of which followed 9,423 participants from state mental hospitals and a nursing home.
In this particular trial, one group of people replaced their saturated fat intake with linoleic acid from corn oil and corn oil polyunsaturated margarine.
In the other group, which acted as a control group, people consumed diets high in saturated fat, including butter and common margarines.
The research team found that those in group one had a "significant reduction" in cholesterol levels, however they also experienced a higher rate of death.
There was also "no evidence of benefit" in terms of heart disease or risk of heart attack, PA reports.
The same team had also previously examined unpublished data from a similar trial - the Sydney Diet Heart Study - and found that the risk of death from heart disease was higher in those who replaced saturated fat with vegetable oil rich in linoleic acid.
They have now reviewed and analysed the results of all similar trials and failed to find any reduction in death from heart disease or other causes.
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Writing in the British Medical Journal (BMJ), they concluded: "Available evidence from randomised 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."
Jeremy Pearson, associate medical director at the British Heart Foundation (BHF), said: "We know that having too much cholesterol in your blood can increase your risk of cardiovascular disease, including heart attack and stroke, which is why managing our cholesterol level is crucial.
"This is an interesting study which shows that decreasing your intake of saturated fat can have a positive impact in helping lower cholesterol.
"However, more research and longer studies are needed to assess whether or not eating less saturated fat can reduce your risk of cardiovascular death."
