We've previously considered the question:
What is an ideal level of omega-3 fatty acids in the blood?
Recall that omega-3 levels in red blood cells (RBCs), a measure called the "omega-3 index," have been associated with risk for sudden cardiac death:
In a recent analysis, 265 people experiencing sudden death during a heart attack (ventricular fibrillation, successfully resuscitated) showed an omega-3 index of 4.88%, while 185 people not experiencing sudden death during a heart attack showed an omega-3 index of 6.08%.
We have more ambitious goals than just avoiding sudden death, of course! How about the omega-3 index associated with reduced risk for heart attack ? A recent analysis of females from the Harvard School of Public Health suggested that RBC omega-3 levels as high as 8.99% were still associated with non-fatal heart attack (myocardial infarction), compared to 9.36% in those without heart attacks, suggesting that even higher levels are necessary to prevent non-fatal events.
Most recently, another study comparing 50 people after heart attack with 50 controls showed that people with heart attack had an omega-3 index of 9.57% vs 11.81% in controls--even higher. (This study was in a Korean population with higher fish consumption. There was also a powerful contribution to risk from trans fat RBC levels.) The investigators concluded: "The area under the receiver operating characteristic curve of fatty acid profiles was larger than that for traditional risk factors, suggesting that fatty acid profiles make a higher contribution to the discrimination of MI cases from controls compared with modified Framingham risk factors ."
The data suggest that, while an omega-3 index of 7.3% is associated with reduced risk for sudden cardiac death, a higher level of 10% or greater is associated with less risk for heart attack. Surprisingly, fish consumption and fish oil intake account for only 47% of the variation in omega-3 index.
I believe the emerging data are becoming increasingly clear: If you desire maximal control over heart health, know your omega-3 index and keep it 10% or higher.