ACP Journal Club. Review: replacing dietary saturated fatty acids with n-6 polyunsaturated fatty acids does not reduce mortality.

Commentary Ramsden and colleagues provide an updated meta-analysis of the effects of dietary LA for secondary prevention of CHD and death, adding data from the SDHS, which was conducted from 1966 to 1973. A central question focuses on the CV effects of replacing saturated fat in the diet with n-6 (“omega-6”) PUFAs, primarily in the form of LA, compared with replacing saturated fat with a combination of n-6 and n-3 (“omega-3”) PUFAs. The authors conclude from their updated meta-analysis that n-6 PUFAs are associated with no indication of CHD benefit and an increased risk for CHD and all-cause mortality when they are substituted for saturated fat without n-3 PUFAs, although the effects were not statistically significant. A proposed mechanism that may contribute to these effects is increased susceptibility of low-density lipoprotein (LDL) that is enriched with n-6 LA to oxidation; increased LDL oxidation may contribute to CV disease.