Omega-3 fatty acids are nutritional dynamos. They reduce inflammation, help the heart recover from a heart attack and ease depression. Now it appears their benefits are even more fundamental — they can increase longevity by slowing the cellular damage associated with aging.

Omega-3 fatty acids help protect telomeres, the protective caps of DNA at the end of chromosomes, from inflammation, the study by researchers at Ohio State University and the University of California at San Francisco found. Shorter telomeres are a sign of premature aging. High levels of omega-3 fatty acids in the blood were associated with longer telomeres.

Omega-3 supplements prevented a decrease in telomerase levels and levels of cortisol in those who got them. People who received the placebo did not see these improvements.

“The findings suggest omega-3 supplements can help break the chain between stress and negative health events,” Annelise Madison, lead author on the study, told TheDoctor.

About 140 overweight middle-aged men and women were enrolled in the study. Participants engaged in fewer than two hours per week of vigorous physical activity and had a body mass index, or BMI, between 22 to 50. Participants were selected at random to receive either a placebo supplement, 1.25 grams a day (g/d) of omega-3 or 2.5 g/d of omega-3. The 2.5 grams-a-day dose of omega-3 is more than what most Americans get through their daily diet, according to Madison, a doctoral candidate in clinical psychology at Ohio State.

To trigger a stress response, participants had to prepare and give a five-minute speech to a panel of judges and complete a short math exercise in front of the same panel. But before they completed these tests, participants had their blood drawn to measure baseline levels of telomerase, an enzyme that helps rebuild telomeres and cytokines, small proteins that play a role in the body’s immune and inflammation responses. They also provided saliva samples to measure baseline levels of the stress hormone cortisol.

Blood was also drawn at 45 minutes and two hours after the tests. Saliva samples were taken immediately after the tests, and also collected at 45 minutes, one hour and 15 minutes, one hour and 45 minutes, and two hours afterward. The tests were repeated and blood and saliva samples were obtained from those given either the placebo or the omega-3 supplements four months later.

Those who received the highest, 2.5 g/d dose of omega-3 reduced their levels of cortisol by an average of 19 percent, and of interleukin-6, a proinflammatory cytokine, by an average of 33 percent, compared to those participants given a placebo.

Both the high and low doses of omega-3 supplements prevented a decrease in telomerase levels and levels of interleukin-10, an antiinflammatory cytokine, in study subjects. People who received the placebo did not see these improvements; in fact, their telomerase levels decreased by an average of 24 percent and their IL-10 levels decreased by an average of at least 20 percent.

These findings are particularly significant because people in the study were overweight and sedentary, and thought to be at high risk for accelerated aging.

Foods like salmon and avocados that are rich in omega-3s can give our bodies the reserves they need, but the researchers found that supplements work well, too and can fill the gaps if we aren't getting enough in our diet.

The study is published in Molecular Psychiatry.