Br J Nutr. 2010 Dec;104(11):1586-600. doi: 10.1017/S0007114510004010.
n-6 fatty acid-specific and mixed polyunsaturate dietary interventions have different effects on CHD risk: a meta-analysis of randomised controlled trials.
Ramsden CE, Hibbeln JR, Majchrzak SF, Davis JM.
"For non-fatal myocardial infarction (MI)+CHD death, the pooled risk reduction for mixed n-3/n-6 PUFA diets was 22 % (risk ratio (RR) 0.78; 95 % CI 0.65, 0.93) compared to an increased risk of 13 % for n-6 specific PUFA diets (RR 1.13; 95 % CI 0.84, 1.53)."
"Risk of non-fatal MI+CHD death was significantly higher in n-6 specific PUFA diets compared to mixed n-3/n-6 PUFA diets (P = 0.02)."
"RCT that substituted n-6 PUFA for TFA and SFA without simultaneously increasing n-3 PUFA produced an increase in risk of death that approached statistical significance (RR 1.16; 95 % CI 0.95, 1.42). "Advice to specifically increase n-6 PUFA intake, based on mixed n-3/n-6 RCT data, is unlikely to provide the intended benefits, and may actually increase the risks of CHD and death."
Strike three. And please note that n-6 was substituted for TFA (trans fats) as well as SFA, and TFA have strongly negative health effects even at a low % energy:
"A meta-analysis of prospective studies indicated 24, 20, 27 and 32% higher risk of myocardial infarction (MI) or CHD death for every 2% energy of TFA consumption isocalorically replacing carbohydrate, SFA, cis monounsaturated fatty acids and cis polyunsaturated fatty acids, respectively."
Again, it's easy to cherry-pick one single study, or even one single meta-analysis. It takes a long time to become familiar enough with the research to get a bigger picture...much longer than it takes to justify a pre-existing prejudice with a few footnotes.
EIDT TO ADD: Stephan Guyenet did a great debunking of the Mozaffarian paper back in the day:
Not only did it fail to distinguish n-3 from n-6 PUFA, it simply omitted several trials that found highly unfavorable results for n-6 interventions, like the Rose Corn Oil Trial and Sydney Diet-Heart Trial. Result: junk science.