Both butter and margarine are around 80 per cent fat, but they contain different types of fat. Butter is higher in saturated fat, at about 52 per cent, whereas the saturated content of margarine varies from 15 to 40 per cent, depending on the blend of oils it contains. In the past, margarines had high levels of trans fats that could have a worse effect on blood cholesterol levels than saturates, but manufacturers have mostly removed these. Other spreads vary in their fat content (20-60 per cent) but lower fat usually means a worse taste. It’s best to choose a spread according to your taste preference and use it only in small amounts.