Lowering the intake of trans fatty acids (TFA) probably reduces the incidence of coronary heart disease. Estimates of the reduction vary from 4% based on changes in plasma LDL and HDL concentrations alone, to > 20% based on epidemiological associations when TFA intake is lowered by 2% of energy (5 g/day). Even the lowest estimate represents enough cases to justify measures to reduce TFA intake. In The Netherlands, a major reduction in TFA content of retail foods has been achieved in the 1990s through efforts of industry; government intervention has been minimal. Societal pressure is now helping to reduce the TFA content of fast foods. McDonald's French fries in The Netherlands now have less than 4% trans and 24% saturates, as opposed to 21% trans and 21% saturates in the USA. This illustrates the feasibility of reducing TFA in fast foods without increasing saturates. As a result of these developments, dairy and meat have become the major remaining source of TFA in Europe. The question whether these ruminant TFA have the same effect on coronary heart disease risk as industrial TFA has not been settled.