This is a systematic review and meta-analysis of randomized controlled trials, performed by the Cochrane collaboration – an independent organization of scientists.
It is probably the best review you can find on this at the moment, and includes 15 randomized controlled trials with over 59,000 participants.
Each of these studies had a control group, reduced saturated fat or replaced it with other types of fat, lasted for at least 24 months and looked at hard endpoints, such as heart attacks or death.
Results: The study found no statistically significant effects of reducing saturated fat, in regard to heart attacks, strokes or all-cause deaths.
Although reducing saturated fat had no effects, replacing some of it with polyunsaturated fat led to a 27% lower risk of cardiovascular events (but not death, heart attacks or strokes).
Conclusion: People who reduced their saturated fat intake were just as likely to die, or get heart attacks or strokes, compared to those who ate more saturated fat.
However, partially replacing saturated fat with polyunsaturated fat may reduce the risk of cardiovascular events (but not death, heart attacks or strokes).
These results are similar to a previous Cochrane review, done in 2011 (2).
Hooper L, et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Systematic Review, 2015.