A modified diet has been advocated for the past 50 years for prevention of cardiovascular disease. The evidence has in the past been largely epidemiological and experimental, with relatively limited support from clinical trials. However a major element of this strategy, reduction in intake of saturated fats, has recently been called into question; the evidence for and against this view is critically reviewed. A Cochrane review, and recent trials, have advanced our understanding of the role of diet and of optimal dietary recommendation strategy. Here we consider these advances in the light of established knowledge.