Replacing saturated fats with healthier options can cut the risk of heart disease by a fifth, a US study says.
The Harvard Medical School reports adds weight to the growing evidence about polyunsaturated fats, found in some fish and vegetable oils.
The team analysed the findings from eight previous studies, covering more than 13,000 people, in their research.
Experts said cutting down on saturated fats, found in butter and meat, was just one part of a healthy diet.
It is recommended that adults get no more than 11% of their energy from saturated fats.
This is because the fats raise the levels of bad cholesterol that block the arteries to the heart.
In comparison, polyunsaturated fats have the opposite effect by increasing the levels of good cholesterol.
The Harvard analysis suggested that for every 5% increase in polyunsaturated fat consumption there was a 10% fall in heart disease.
The average rise in uptake of such fats was 10% giving the overall figure of a fifth lower risk over a period of just over four years.
Lead researcher Dariush Mozaffarian said there was always a risk cutting down on saturated fats meant they were replaced with other bad options such as trans-fats which are found in processed foods such as biscuits and cakes.
He added: "Our findings suggest that polyunsaturated fats would be a preferred replacement for saturated fats for better heart health."
Victoria Taylor, from the British Heart Foundation, said the research reinforced existing recommendations to reduce saturated fats.
But she added: "What this study doesn't consider is whether substitution with monounsaturated fats, such as olive and rapeseed oils, would have similar benefits so more research is needed to understand this area fully.
"While the fat content and profile of your diet is clearly important, it must also be seen as just one part of a heart healthy diet where a low saturated fat and salt intake is combined with the consumption of oily fish and at least five portions of fruit and vegetables a day."