Consuming more omega-3 fatty acids preserves lung function in healthy adults

Key takeaways:

• Among downstream omega-3 fatty acids, docosahexaenoic acid was linked to the largest reductions in FEV₁ and FVC decline.
• Genetically predicted omega-3 fatty acids were also related to better lung function.

In healthy adults, higher levels of omega-3 fatty acids promoted lung health by lowering the rate of yearly lung function decline, according to results published in American Journal of Respiratory and Critical Care Medicine.

“The study provides the strongest evidence to date of a relationship between omega-3 fatty acids found in fish and lung health and underscores the importance of including omega-3 fatty acids in the diet, especially given that many Americans do not meet current guidelines,” Patricia A. Cassano, MPH, PhD, director of the division of nutritional sciences and the Alan D. Mathios Professor at Cornell University, told Healio.

In a longitudinal observational study of data from the National Heart, Lung, and Blood Institute Pooled Cohorts Study, Cassano and colleagues evaluated 15,063 individuals (mean age, 56 years; 55% women; 69% white; 20% Black; 48% never smokers) to determine if omega-3 fatty acids in blood are linked to less lung function decline, as measured by FEV₁ and FVC. This analysis was followed by a two-sample Mendelian randomization study for further investigation of the relationship between the two factors.

“The two-part approach of combining a longitudinal study with large genetic analysis was to ensure any association we found was consistent across different analytic methods and backed by as much data as possible,” Cassano told Healio.

Researchers specifically evaluated four different omega-3 fatty acids — alpha-linolenic acid (ALA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

Each participant underwent an average of 2.6 spirometry measurements, with 23% of patients at baseline showing airway obstruction.

Following adjustments for sex, age, weight, height, smoking status, baseline smoking pack-years and cigarettes smoked per day, researchers found that decreases in FEV₁ and FVC slowed with elevated relative ALA, EPA and DHA levels. The greatest reduction in both FEV₁ and FVC declines was found with one standard deviation (SD) higher DHA (FEV₁, 1.77 mL/year; FVC, 2.43 mL/year), followed by ALA (FEV₁, 0.77 mL/year; FVC, 1.3 mL/year) and EPA (FEV₁, 0.62 mL/year; FVC, 0.84 mL/year; P < .005 for all).

Among the three omega-3 fatty acids, DHA continued to have a statistically significant relationship with both FEV₁ (0.94 mL/year) and FVC (1.37 mL/year) decline following additional adjustment for the effects of sex, smoking and race/ethnicity on reduced lung function, according to researchers.

This relationship between DHA and reduced rates of lung function decline was observed in men and women; never, former and current smokers; and white, Black and Hispanic individuals. Hispanic individuals had the greatest magnitude association at a 4.3 mL/year reduction in FEV₁ decline per one SD higher DHA, and within smoking status subgroups, former smokers demonstrated the largest reduced decline (2.2 mL/year).

“We observed the strongest and most consistent results for docosahexaenoic acid (DHA), an omega-3 fatty acid that is found at high levels in fatty fish such as salmon, tuna and sardines,” Cassano told Healio.

When comparing the relative levels of each omega-3 fatty acid in the 1,455 airway obstruction cases that occurred over the study period with individuals without airway obstruction, researchers found that DHA accounted for a smaller proportion of total fatty acids in those with airway obstruction (3.23% vs. 3.29%; P = .05).

Researchers did not find differences in levels of the other three omega-3 fatty acids between both groups.

Notably, the risk for airway obstruction went down with more DHA (HR per SD = 0.91; 95% CI, 0.87-0.97) and went up with more ALA (HR per SD = 1.08; 95% CI, 1.03-1.13) after accounting for covariates.

Lastly, researchers found positive links between both FEV₁ and FVC and genetically predicted EPA, DPA, DHA and total omega-3 fatty acids in the MR study.

“The current study only included healthy adults,” Bonnie K. Patchen, PhD, nutritionist and member of Cassano’s research team, told Healio. “As part of this ongoing project led by Patricia Cassano and Dana Hancock, PhD, from RTI International, the researchers are collaborating with the COPDGene study. They are studying the blood levels of omega-3 fatty acids in relation to the rate of decline in lung function among persons with COPD — including heavy smokers — to see if the same associations are found that were seen in the current study. Those results are not yet available.”

Reference:

• NIH-funded study supports new role for nutrient found in fish, dietary supplements. https://www.nih.gov/news-events/news-releases/omega-3-fatty-acids-appear-promising-maintaining-lung-health. Published July 20, 2023. Accessed July 20, 2023.