Study: People Who Eat More Fish Live Longer

Members of the 64-and-older set whose blood is rich in dietary omega-3s lived an average of 2.2 years longer.

Thierry Roge/Reuters

PROBLEM:  We learned last year that omega-3 supplements, through some of kind of wonder that the fatty acids work on our DNA, might help counteract the effects of aging on a molecular level. If the ultimate effect of aging is dying, we should hope that omega-3s might help extend life, and their case is strengthened by the fact that they are known to have a protective effect on the heart. Reports that popping fish oil pills doesn't seem to do much to prevent heart disease, however, confuse the issue. So what if we forget about how they got there and just focus on the bottom line: Are people with more omega-3s in their blood healthier?

METHODOLOGY: A joint effort from the Harvard School of Public Health and the University of Washington analyzed data from 2,700 U.S. adults over the age of 64. All started out healthy, with various proportions of omega-3s in their blood, and were subjected to blood tests and other evaluations over 16 years of follow-up. The researchers compared that initial omega-3 measurement to how long the participants went on living. They also asked the participants -- none of whom took omega-3 supplements -- how much fish they included in their diets.

RESULTS: Having higher levels of blood omega-3s was associated with a 27 percent decrease in overall mortality risk, and with a 35 percent decrease in the risk of mortality from heart disease. All of this was established with blood tests, and it was correlated with how much fish they reported eating.

One specific omega-3 -- known as DHA -- was associated with a 40 percent decreased risk of dying from coronary heart disease, and was particularly associated with a reduction in death caused by arrhythmia.  Meanwhile, the omega-3 EPA, had a particularly strong link to decreased risk of nonfatal heart attack. The participants' levels of both were linked to their diet; a third, DPA, was strongly associated with lowered stroke death, but was not correlated with fish intake.

IMPLICATIONS: Since none of the people followed took fish-oil supplements, the omega-3 in their blood that didn't result from metabolic processes presumably came from their diets. Sure enough, how much fish the participants claimed they ate, on average, was correlated with their longevity (however, the authors didn't look at other potential dietary sources of omega-3s). The overall association with reduced mortality was strongest for people who consumed what they quantified as the equivalent of about two servings of fish per week, as compared to those who had minimal omega-3 intake. So fish pills might not be necessary, nor should be figuring out how to incorporate fish into everything we eat. Just eating some fish, instead of no fish, should do the trick.

"Plasma Phospholipid Long-Chain Omega-3 Fatty Acids and Total and Cause-Specific Mortality in Older Adults," is published in Annals of Internal Medicine.