The study authors focused on so-called healthy ageing, or the number of years people live without developing disabilities or physical or mental health problems.
They examined data on 2,622 adults who were 74 years old on average, following them from 1992 to 2015. Only 11 per cent of participants experienced healthy ageing throughout the entire study period.
“We found that older adults who had higher levels of omega 3 from seafood were more likely to live longer and healthier lives,” said lead study author Heidi Lai of the Friedman School of Nutrition Science and Policy at Tufts University in Boston.
“These findings support current national dietary guidelines to consume more seafood,” said Lai said.
Adults should get about eight ounces a week of seafood, ideally by eating it twice a week in place of meats, poultry or eggs, according to U.S. dietary guidelines. Some options that are high in omega 3s include salmon, anchovies, herring, shad, sardines, oysters, trout and Atlantic or Pacific mackerel.
In the current study, people with the highest blood levels of omega 3 fatty acids were 18 per cent to 21 per cent less likely to experience unhealthy ageing, researchers report in the BMJ.
Researchers measured blood levels of omega 3s at the start of the study and again after six and 13 years had passed. These included eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), and alpha linolenic acid (ALA). The main dietary sources of EPA, DHA and DPA come from seafood, while ALA is found mainly in nuts, seeds, and leafy green vegetables.
Based on these measurements, researchers split participants into five groups, or quintiles, from lowest to highest levels of circulating omega 3s.
Overall, 89 per cent of the participants experienced unhealthy ageing during the study period.
After accounting for social, economic, and lifestyle factors, researchers found that people with the highest levels of seafood-derived EPA were 24 per cent less likely to experience unhealthy ageing that individuals with the lowest levels of EPA.
For DPA levels, participants in the top three quintiles were 18 to 21 percent less likely to experience unhealthy aeging. But seafood-derived DHA and plant-derived ALA didn’t appear to influence the chance of healthy ageing.
A possible explanation for this effect is that omega 3’s help to regulate blood pressure, heart rate and inflammation, the study authors note.
Previous research has linked omega-3s to a lower risk of abnormal heartbeats, less fats in the blood, reduced risk of artery-clogging deposits known as plaque, and slightly lower blood pressure.
The current study wasn’t a controlled experiment designed to prove whether or how omega 3’s might directly influence health. Another drawback is that it didn’t look at omega 3 supplements.
It would be premature for people to make health decisions based on this study, said Yeyi Zhu of Kaiser Permanente Northern California and the University of California, San Francisco.
“There has been accumulating evidence suggesting an inverse association between omega 3 fatty acids in food and the likelihood of cardiovascular diseases,” Zhu, author of an accompanying editorial, said by email. “However, the data are inconsistent on other components of health ageing.”