Omega-3 fatty acids, which are abundantly found in fish and fish oil supplements, play an important protective role in long-term lung health, as new evidence from a large multi-faceted study in healthy adults indicates.
Funded by the National Heart, Lung and Blood Institute (NHLBI), which is part of the National Institutes Health (NIH) in US, results of the study have been published in the American Journal of Respiratory and Critical Care Medicine.
There is growing interest in trying to understand whether nutritional interventions could contribute to lung disease prevention efforts. While a few studies in the past have suggested that omega-3 fatty acids may help largely due their established anti-inflammatory actions, there have been no substantiative studies which could confirm this association, until now.
“We know a lot about the role of diet in cancer and cardiovascular diseases, but the role of diet in chronic lung disease is somewhat understudied," said Dr Patricia A Cassano, director of the division of nutritional sciences at Cornell University(Ithaca, New York) and a corresponding author of the study. “This study adds to growing evidence that omega-3 fatty acids, which are part of a healthy diet, may be important for lung health too.”
To investigate the link between omega-3 fatty acid levels in the blood and lung function over a period of time, the researchers developed a two-part study. In the first part, they conducted a longitudinal, observational study involving 15,063 Americans from the NHLBI pooled cohorts study - a large collection of NIH-funded studies that helps researchers to examine the determinants of personalised risk for chronic lung disease.
Majority of the participants, considered for the first part of this study, had no evidence of chronic lung disease and were generally healthy when the study began. They comprised a racially diverse group of adults, with an average age of 56 years and 55% were female. Researchers observed and collected relevant data from the select group of participants for an average of seven years and up to a maximum of 20 years.
Observational data indicated that higher levels or omega-3 fatty acids in a person’s blood were associated with a reduced rate of decline in lung function. Researchers observed the strongest associations for docosahexaenoic acid (DHA), an omega-3 fatty acid that is found in high levels in fatty fish such as salmon, tuna and sardines. DHA is also available as a dietary supplement for those who are unable to consume fish.
For the second part of the study, researchers analysed genetic data from a large study of European patients (over 500,000 participants) from the UK Biobank. As an indirect measure or proxy for dietary omega-3 fatty acid levels, they studied certain genetic markers in the blood to see how they are correlated with lung health. Results indicated that higher levels or omega-3 fatty acids, including DHA, were associated with better lung function.
Researchers are, however, aware that this current study has only included healthy adults. As part of a larger ongoing project, they are now collaborating with the COPD (chronic obstructive pulmonary disease) gene study to examine blood levels of omega-3 fatty acids in relation to the rate of decline in lung function, among people with COPD, including heavy smokers, to determine if the same beneficial associations are found.
“We're starting to turn a corner in nutritional research and really moving toward precision nutrition for treating lung diseases. In the future, this could translate into individualised dietary recommendations for people at high risk for chronic lung disease,” said Dr Bonnie K Patchen, a nutritionist and member of Dr Cassano's research team at Cornell.
For now, the researchers point out that the US department of agriculture's dietary guidelines for Americans recommends that people eat at least two servings of fish per week, which most Americans fall far short of. In addition to fish and fish oil, other sources of omega-3 fatty acids include nuts and seeds, plant oils and fortified foods.
Dr James P Kiley, director of the NHLBI's division of lung diseases, said, “This large population-based study suggests that nutrients with anti-inflammatory properties may help to maintain lung health. More research is needed, since these findings raise interesting questions for future prospective studies about the link between omega-3 fatty acids and lung function.”