It is known that asthma and other allergic reactions are triggered by allergens that induce the overproduction of IgE. IgE, mast cells, basophils, and eosinophils are the essential components of allergic inflammation that trigger allergic responses including asthma. People with asthma have an imbalance between molecules that dampen inflammation and those that increase excessive inflammation, including higher levels of IgE. For many years, physicians have prescribed steroids (both inhaled and oral) as a treatment for asthma. While these corticosteroids do help control the inflammation and relieve asthma symptoms, they can also have numerous adverse side effects, especially if taken orally. And while oral steroids can dramatically reduce asthma symptoms, they do not cure the underlying disease. Recent evidence suggests that they appear to reduce the body’s ability to use essential omega-3 fatty acids to reduce inflammation and asthma symptoms.
A recent study by researchers at the University of Rochester Medical Center (URMC) published in the Journal of Clinical Investigation found that omega-3 fatty acids can help reduce the inflammatory response seen in patients with asthma. Using white blood cell cultures from a group of 17 asthma patients and a group of healthy control subjects, the researchers (led by Richard P. Phipps, Ph.D.) found that the addition of omega-3 fatty acids to cultured white blood cells reduced the production of IgE. Elevated IgE levels are produced by certain white blood cells (B-lymphocytes) typically in response to small amounts of proteins (or allergens). High levels of IgE trigger allergic reactions. So lower levels of IgE induced by omega-3s can help reduce the allergic reactions that trigger asthmatic symptoms naturally without the adverse side effects seen with chronic oral steroid use. URMC researchers showed that patients with more severe asthma who were taking higher doses of oral steroids that the beneficial impact of omega-3 fatty acids on inflammation were significantly reduced probably because the corticosteroids were blocking the production of inflammatory substances made by the omega-3 fatty acid precursors.
Dr. Phipps and his team isolated B-lymphocytes (or B-cells) from asthma patients and healthy controls. Co-authors Nina Kim, Ph.D. and Patricia Sime, M.D. then compared the impact on the B-cells from the 17 asthma patients with the B-cells from healthy blood donors. They then examined the impact of pure omega-3-derived molecules on IgE and other molecules that promote asthma symptoms. Most of the asthma patients who volunteered for the study were taking corticosteroids in either pill form or by inhaler, depending upon severity of their asthma. Results showed that all responded to the omega-3 fatty acids to some degree. But unexpectedly, Phipps said, the cells from the subset of patients who were taking oral steroids were less sensitive to the omega-3 treatment. Steroids are usually a very effective treatment for severe asthma. However, although the science is in the early stages, it appears that when corticosteroids are used continuously, the steroids can reduce some of the body's natural ability to fight asthma-related inflammation. The results from Dr. Phipps and associates’ study demonstrate that immunosuppressive oral corticosteroids appear to suppress the body's endogenous resolution pathways in a way that may actually exacerbate allergic disease process.
Dr. Phipps's discovery that omega-3 fatty acids may reduce inflammation and asthma symptoms in those with asthma coincides with a study in the New England Journal of Medicine (NEJM) published late December 2016, which showed that pregnant women who took fish oil supplements reduced the risk of wheeze and asthma symptoms in children by about 33% on average. Dr. Phipps noted that the fish oil supplements used as a dietary supplement in the NEJM study were a special high-quality preparation and suggested consumers should use caution when buying over-the-counter fish oil supplements because not all such products are the same.
Another dietary factor that appears to increase the severity of asthma symptoms is an excessive intake of salt. A low-sodium diet maintained for 1 to 2 weeks has been shown to decrease bronchoconstriction in response to exercise in individuals with asthma. While there little evidence regarding the longer-term effects of a low-sodium diet on either the prevalence or severity of asthma or on exercise-induced bronchospasm, reducing the salt intake of those with asthma seems prudent because a low-sodium diet has other beneficial health effects. It can be considered another therapeutic option along with adequate omega-3 PUFA intake for people with asthma. While reducing salt and increasing omega-3s should be considered safe and effective interventions that may reduce asthma symptoms, neither should be considered a substitute for optimal pharmacotherapy in those with severe, life-threatening asthma.
Bottom Line: There is no doubt that omega-3 polyunsaturated fatty acids are essential fatty acids and an adequate intake has been shown to have numerous health benefits. Omega-3 fatty acids are needed to produce biochemical mediators that can inhibit the excessive inflammation associated with asthma. A reduction in dietary salt and an increased intake of omega-3 PUFA may reduce asthmatic attacks without also suppressing other parts of the immune system or causing other serious side effects as are frequently seen with the chronic use oral corticosteroids. Omega-3s can be found not only in fish like salmon, trout, mackerel, sardines, herring, and anchovies but also in plant foods such as flax seeds, chia seeds, and walnuts. Until we have more information about specific omega-3 PUFAs, pregnant women concerned about their children developing asthma should be advised to consume at least 3-4 servings of these omega-3 rich foods a week. And people with asthma may want to consume more omega-3 rich foods, reduce their intake of salt and salt-rich foods, and talk with their MDs about perhaps limiting the use of chronic long-term use of oral corticosteroids, except as really needed to control severe asthmatic symptoms.
By James J. Kenney, PhD, FACN
 Nina Kim, Thomas H. Thatcher, Patricia J. Sime, Richard P. Phipps. Corticosteroids inhibit anti-IgE activities of specialized proresolving mediators on B cells from asthma patients. JCI Insight, 2017; 2 (3) DOI: 10.1172/jci.insight.88588.
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.