A US study suggets replacing saturated fats with healthier options can cut the risk of heart disease by a fifth. The Harvard Medical School reports adds weight to the growing evidence about polyunsaturated fats, found in some fish and vegetable oils. In their research, the team analysed the findings from eight previous studies, covering more than 13,000 people. <br/><br/>Experts said cutting down on saturated fats, found in butter and meat, was just one part of a healthy diet. 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. <br/><br/>The Harvard analysis suggested that for every 5 per cent increase in polyunsaturated fat consumption there was a 10 per cent fall in heart disease. The average rise in uptake of such fats was 10 per cent giving the overall figure of a fifth lower risk over a period of just over four years.