AbstractDietary intervention trials are cause effect studies with the disadvantage of measuring disease risk factor endpoints as opposed to disease endpoints. One approach towards overcoming this disadvantage is to use a measure of vascular function as an endpoint. There are two dietary strategies for lowering the intake of saturated fat. One is to replace the saturated fat with monounsaturated fat and the other is to replace it with carbohydrate. It is difficult to decide from the results of intervention trials with disease risk factor endpoints, which of these strategies is better for health. After allowance has been made for defects in design, measurements of vascular function suggest that replacing saturated fat with monounsaturated fat is better for the cardiovascular system.