The role of fat in the diet - quantity, quality and sustainability

Dietary fat should supply at least 15% of food energy including 2.5% energy and 0.5% energy as linoleic acid and alpha-linolenic acid respectively: docosahexaenoic acid may also need to be supplied in infants. The proportion of energy from fat is not linked to risk of obesity, cardiovascular disease and cancer. The total cholesterol/ HDL cholesterol, which is the most robust lipid indicator of risk of coronary heart disease (CHD), is lowered by unsaturated fatty acids, increased by trans fatty acids and not affected by saturated fatty acids compared with carbohydrates. Using clinical outcomes as endpoints, trans fatty acids increase, polyunsaturated fatty acids decrease and monounsaturated and saturated fatty acids have no effect on CHD risk. Recent recommendations for the prevention of CHD suggest partial replacement of saturated with polyunsaturated fatty acids to give energy intakes in the range of 6-11% energy and a daily intake of 0.25 g long-chain n-3 polyunsaturated fatty acids. The recommendation to increase the intake of longchain n-3 fatty acids needs to be considered against the backdrop of falling fish stocks; it is likely that a novel source will be needed in the future. The projected growth in world population will require more fat, mainly for food energy. The oil palm requires only one tenth of the land required by oil seeds to produce the same amount of oil. The impact of increased use of vegetable oils as biodiesel needs to be urgently reconsidered owing to the adverse environmental and economic consequences to people living in South East Asia.