Asthma severity linked to fatty acid intake in children
In children, a diet higher in omega-6 fatty acids may worsen asthma severity and response to indoor particulate air pollution, whereas increased consumption of omega-3 fatty acids may have beneficial effects, new data from the AsthmaDIET study suggest.
In the study, after adjustment for confounders, higher dietary intake of omega-6 fatty acids was associated with increased odds for more severe asthma (OR = 1.29; P = .02) and lower forced expiratory volume/forced vital capacity (FEV1/FVC; beta = –0.012; P = .01). In contrast, omega-3 intake was not associated with asthma severity or FEV1/FVC.
“There is mounting evidence that diet, particularly omega-3 and omega-6 fatty acids, may play a role in lung health,” Emily P. Brigham, MD, MPS, assistant professor of medicine at Johns Hopkins University, said in a press release.
For the study, Brigham and colleagues evaluated data from 135 children (mean age, 9.5 years; 47% girls; overweight or obese, 50%) in Baltimore. Most were black (96%), had public insurance (91%) and had caregivers who reported having at least a high school education (71%). Approximately one-third of participants had mild asthma, one-third had moderate asthma and one-third had severe asthma. In the 2 weeks before the study, 66% reported albuterol use and 47% reported inhaled corticosteroid use.
Participants underwent 1-week assessments of indoor particulate matter concentrations, dietary intake of omega-3 and omega-6 fatty acids, daytime and nocturnal asthma symptoms collected via daily diary and peripheral blood leukocytes at baseline, 3 months and 6 months. Information on weeklong indoor particulate matter concentrations was obtained using impactors designed to collect particles 2.5 m or less (PM2.5) and 10 m (PM10) or less that were placed in the home.
“Many children in the U.S., including those in Baltimore City, where we conducted our research consume a diet that deviates sharply from national guidelines. Typically, this means they are eating low amounts of omega-3 and higher amounts of omega-6,” Brigham said in the release. “Because children with asthma are already prone to inflammation and respiratory symptoms, we wanted to see if these fatty acids could be further contributing to their disease severity and symptoms in response to indoor air pollution, which is often elevated in inner-city homes.”
Effects on asthma symptoms
Children in the study reported daytime asthma symptoms on 19.8% of 2,068 days, including trouble breathing on 18.8% of days, bother due to asthma on 16.5% of days and limitation in activity due to asthma on 13.3% of days. Nocturnal symptoms were reported on 6.8% of 2,412 days and albuterol use was reported on 18% of 2,135 days. The number of days per outcome measure varied because some participants missed daily entries in their diaries.
Omega-3 and omega-6 intake did not demonstrate a primary effect of PM2.5 and PM10 exposure on daytime symptoms, albuterol use or nocturnal symptoms. However, higher levels of omega-6 intake strengthened the effect of PM2.5 (P < .01) and PM10 (P = .03) on daytime symptoms, whereas the effect was reduced with higher intake of omega-3 intake (P < .01). Further, the harmful effects of omega-6 on the association between indoor PM2.5 or PM10 exposure and asthma symptoms were most pronounced at lower levels of omega-3, whereas the beneficial effects of omega-3 on symptoms were most pronounced at higher levels of omega-6.
Increasing omega-6 intake was also associated with higher percentages of neutrophils in response to circulating levels of particulate matter.
The study was limited by the fact that dietary intake of omega-3 and omega-6 fatty acids was self-reported by children and their caregivers using a Baltimore-specific food frequency questionnaire. Additionally, the study’s observational design precluded the researchers from proving a causal relationship or ruling out other factors that may have affected asthma health.
These results, though, indicate that further research in this area will be important, the researchers noted.
“If there is a causal relationship between diet and asthma, a healthier diet may protect children with asthma, particularly minority children living in the inner city, from some of the harmful effects of air pollution,” Brigham said. “Among vulnerable populations, we may find that improving diet and air pollution together has the greatest impact on asthma health.” – by Melissa Foster
Disclosures: The study was sponsored by grants from the National Institute for Environmental Health Sciences of the NIH, the National Center for Advancing Translational Sciences of the NIH, and the EPA. Healio Pulmonology could not confirm Brigham’s or the other individual authors’ relevant financial disclosures at the time of publication.