Published online: August 23, 2018
There are different types of fat in our diets. Polyunsaturated fatty acids (PUFA), including omega-3 and omega-6 fatty acids, are a type of fat known to have effects on immune function and inflammation and could influence the risk of childhood asthma and allergy. PUFAs are found in a variety of foods, including fatty fish (salmon, mackerel, tuna), walnuts, and flax seeds. A growing body of evidence suggests that increasing intake of PUFA, especially omega-3 fatty acids, during pregnancy can reduce allergic disease in offspring. However, it is not clear whether PUFA intake after birth, during childhood, also has an impact on risk of asthma or allergies.
In a study recently published in The Journal of Allergy and Clinical Immunology: In Practice, Lee-Sarwar and colleagues investigated the association between PUFA and allergic disease in 3-year-old children. Subjects were from a multi-site United States study of vitamin D supplementation during pregnancy to prevent asthma in offspring, and vitamin D levels were measured at birth. When participating children were 3 years old, parents were asked what foods and how much of those foods their child ate, and children provided blood samples for measurement of PUFAs and markers of allergy (total IgE and serum-specific IgE to common allergens). Parents were asked every 3 months until children were 3 years old about wheezing episodes, asthma medication use, and whether their child had been diagnosed with asthma by a health care provider.
Children with higher levels of total, omega-3, and omega-6 PUFAs were less likely to have asthma or recurrent wheeze at age 3 years. This pattern held regardless of whether PUFAs were measured based on dietary intake or blood levels, and after the researchers adjusted for an array of possible confounding variables. Higher blood levels of PUFAs were similarly associated with lower blood markers of allergy. The link between higher PUFA and less asthma/wheeze was strongest in children who had higher levels of vitamin D at birth, suggesting possible synergy between these two nutrients.
These findings add to the evidence supporting dietary interventions such as increased vitamin D and PUFA intake to reduce the burden of allergic disease in childhood. However, the authors caution that because children were not randomized to high or low PUFA intake and because both PUFAs and allergic outcomes were measured at the same time (age 3 years), one cannot conclude from these results that increasing PUFA will cause a reduction in asthma/allergy. Studies following children over time and larger randomized trials are needed to further evaluate this safe and inexpensive potential treatment for childhood asthma and allergies.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.
Low polyunsaturated fatty acid intake linked to childhood allergy
Kathleen A. Lee-Sarwar, MD and Augusto A. Litonjua, MD, MPH