What if there were one simple thing you could do that would decrease your overall mortality risk by 27%, extend your life by an average of 2.2 years, decrease your risk of heart disease by 40%, and decrease your risk of dying from a heart attack caused by arrhythmia by 45%? And what if you could enjoy all of those benefits even if you are already 65 years old or older?
Wouldn't that be something that most people would want to do? And what if the clinical study suggesting that all of that is possible was actually a really well- designed study?
None of the participants in this study had evidence of cardiovascular disease, stroke, or heart failure at the onset of the study. Blood levels of total of omega-3 fatty acids and the specific omega-3 fatty acids DHA, EPA, and DPA, a metabolite of EPA, were measured when each participant was enrolled in the study. Patients taking omega-3 supplements were excluded from the study.
The study followed these participants for a total of 16 years (1992-2008). The health of the participants was assessed by alternating clinic examinations and telephone contacts every six months through 2000 and with biannual telephone contacts afterwards. At the time of the initial clinical assessment cardiovascular risk factors, height and weight measurements, blood pressure, alcohol intake, smoking, and dietary consumption of omega-3 fatty acids were determined. All cause mortality, cause specific mortality, and all suspected cases of fatal or nonfatal heart attacks and stroke were assessed from medical records, death certificates, and interviews with next of kin.
To put the results of this study into perspective it would be good to review the ways in which the design of this study is a significant improvement over the design of most previous clinical trials with omega-3 fatty acids.
For example, most previous observational studies of the effect of omega-3 fatty acids on cardiovascular endpoints or mortality have relied on self-reported dietary intake rather than actual measurement of omega-3 fatty acids in the blood. This is important because self-reported dietary intake is often subject to error and individual differences in the metabolism of omega-3 fatty acids can have significant effects on how much of those omega-3 fatty acids actually get into the bloodstream.
In addition, most double-blind, placebo-controlled clinical studies of omega-3 fatty acids have been performed on patients who are either at high risk of a heart attack or have already suffered a first heart attack. While four early randomized trials of this type showed a significant decrease in coronary events in patients consuming high levels of fish or fish oil supplements, the medical landscape has shifted dramatically in recent years. Nowadays patients at high risk for heart attack or stroke are already on four or five medications that duplicate many of the beneficial effects of the omega-3 fatty acids, so the addition of omega-3 fatty acid supplements in this medicated patient population has shown little or no added benefit in more recent studies. The strength of the current study is that the patients in this study had no apparent cardiovascular risk and were, therefore, not receiving medications that would mask the effect of the omega-3 fatty acids.
Now that you understand the strengths of this study, let me reiterate the main results of the study. Older adults with the highest blood levels of omega-3 fatty acids had a 27% reduction in overall mortality, 35% reduction in risk of dying from heart disease, a 45% reduction in risk of dying from a heart attack caused by arrhythmia, and lived 2.2 years longer than adults with the lowest blood levels of omega-3 fatty acids. That's pretty darn impressive.
The authors concluded: "Because these biomarkers were measured among older adults, our findings suggest that dietary omega-3 fatty acids late in life may reduce total mortality". However, they also pointed out that their data did not distinguish between whether the benefits they observed were due to omega-3 fatty acid consumption in this older population or whether they reflected the influence of lifelong dietary habits.
One interesting, and perhaps unexpected, outcome of this study was that while there was a linear correlation between blood levels of omega-3 fatty acids and decreased risk of cardiovascular and total mortality, the correlation between dietary consumption of omega-3 fatty acids and blood levels of omega-3 fatty acids was distinctly nonlinear. There was a very steep linear correlation between dietary intake and blood levels up to 400 mg per day of omega-3 fatty acids. Above 400 mg per day the increase was still linear but the slope of the increase was much less. However, no plateau in blood levels of omega-3 fatty acids was observed - even up to an intake of 2000 mg per day, the highest dietary intake observed in this study.
There are a couple of important take-home lessons from this observation. First, this study showed that higher dietary intake of omega-3 fatty acids is associated with higher blood levels of omega-3 fatty acids, and the highest blood level of omega-3 fatty acids is associated with the lowest risk of mortality and cardiovascular mortality. However, the biggest "bang for your buck" is clearly associated with the first 400 mg per day of omega-3 fatty acids in your diet. This led the authors to conclude that "the present findings support an average target dietary range of 250 to 400 mg of omega-3 fatty acids per day".
Secondly, since the average intake of omega-3 fatty acids in the United States and many European countries is around 150 mg per day, the authors concluded that addition of an omega-3 supplement to the diet would likely produce "a reduction in cardiovascular mortality of approximately 15%".
So what is the bottom line for you?
1) If you are in your golden years and want to live a longer healthier life, this study suggests that you may want to optimize your blood levels of omega-3 fatty acids.
2) As I noted above this study does not allow me to predict whether the beneficial effect of omega-3 fatty acids are the result of omega-3 fatty acid intake in your golden years or over your lifetime. However, there are so many other health benefits of omega-3 fatty acids that adding more omega-3 fatty acids to your diet is just a good idea.
3) While this study did not detect an upper limit beyond which increased intake of omega-3 fatty acids no longer had any benefit, you clearly get the biggest bang for your buck with the first 400 mg per day of omega-3 fatty acids in your diet.
4) Finally, if you're like most Americans and are only getting around 150 mg per day of omega-3 fatty acids in your diet, you would probably benefit from an omega-3 supplement.
To Your Health!
Dr. Stephen G Chaney
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.