Now here's some more good news: A study published Monday in the Annals of Internal Medicine suggests that eating oily fish once or twice a week could maybe – just maybe — add a few years to your life.
Oily fish like salmon, trout and herring are, of course, a good source of omega-3 fatty acids, which are essential to numerous bodily functions. Researchers at Harvard School of Public Health and the University of Washington wanted to know how eating fish high in omega-3s affected health. So over the course of 16 years, they monitored a group of almost 2,700 healthy adults aged 65 years or older.
But unlike most studies that have looked at the question, the researchers didn't want to rely on study subjects to accurately recall what they ate, so they measured blood levels of omega-3s instead. And since they were interested in dietary intake only, they excluded participants who took fish oil supplements.
After controlling for factors like age, sex and lifestyle, the researchers found that, on average, adults with the highest blood levels of omega-3 fatty acids lived 2.2 years longer. In particular, these adults had a 35 percent lower risk of dying from cardiovascular disease – which is in line with other studies that have tied omega-3s to cardiovascular benefits.
Higher levels of fatty acids were most strongly associated with decreased risk of coronary heart disease and stroke.
"Omega-3 fatty acids are very unique in that, at very small levels in the diet, they have pretty powerful effects on a range of body functions," says Dr. Dariush Mozaffarian, lead author of the study.
According to Mozaffarian, the main reason why omega-3s are important is because of their role in building cell membranes. "Our cell membranes are 95 percent fat," he explains. "If we didn't have fatty acids, we wouldn't have cells."
Omega-3s can stabilize the function of heart cells, says Mozaffarian. They can also alter the way that cells interact with each other and even affect gene function.
Because the study was not a randomized trial, the findings don't actually prove that higher levels of omega-3s are responsible for the observed health benefits. "There still could be ... some mysterious factor that is unknown," Mozaffarian acknowledges.
Nevertheless, Mozaffarian recommends that people, especially those over 65, make an effort to include fish in their diets. "You get the most bang for your buck" by eating one to two servings of fatty fish per week, he says.
However, consuming more than two servings of fish per week doesn't appear to increase blood levels of omega-3s much further. This means that, as long as you eat fish regularly, it's probably unnecessary to take additional fish oil supplements, says Mozaffarian.