Fish oil may help fight asthma, a report from researchers at the University of Rochester Medical Center shows.

The study, “Corticosteroids inhibit anti-IgE activities of specialized proresolving mediators on B cells from asthma patients,” was published in the Journal of Clinical Investigation—Insight.

Asthma is a chronic inflammatory disease, involving lung inflammation and narrowing of the small airways through a combination of excessive mucus production and smooth muscle contraction. The condition is caused by various inflammatory immune cells and proinflammatory mediators.

Immunoglobulin E (IgE) is an antibody produced by B-cells that is critical for the onset and maintenance of both acute and chronic allergic diseases, including asthma. The vast majority of individuals with allergic asthma have elevated serum IgE levels. Because IgE is a key player in allergic asthma, it represents a prime target for therapeutic intervention.

In previous studies, Richard P. Phipps, PhD, the Wright Family Research Professor of Environmental Medicine, and colleagues found that certain fatty acids regulate the function of B-cells. They went further in this study by investigating the effects of omega-3 fatty acids on asthma.

Researchers collected blood samples from 17 patients with asthma at UR Medicine’s Mary Parkes Asthma Center. Patients’ B-cells where isolated, and the team examined the effects of pure omega-3-derived products on IgE and other asthma-trigger molecules. Most patients in the study were taking corticosteroids. The results then were compared to blood cells from healthy donors.

The team found that all patients with asthma responded to omega-3 fatty acids, with a reduction in the levels of IgE antibodies. However, the cells from some of the patients who were taking oral steroids were less sensitive to the omega-3 fatty acids.

Steroids are an effective asthma treatment, and work by reducing inflammation, swelling, and mucus production in the airways. As a result, the airways are less inflamed and less likely to react to asthma triggers, allowing people with symptoms of asthma to have better control over their condition.

Omega-3 fatty acids therefore can reduce the production of IgE in asthma patients. However, in patients with severe disease under treatment with oral steroids, the effects of omega-3 fatty acids are less noticeable because the drugs block its beneficial effects.

Phipps also noted that studies have shown that in some cases the regular use of steroids can reduce some of the body’s natural ability to fight asthma-related inflammation.

The new study coincides with a study titled “Fish Oil–Derived Fatty Acids in Pregnancy and Wheeze and Asthma in Offspring,” published in 2016, which showed that exposure to fish oil in the third trimester of pregnancy reduced the absolute risk of persistent wheeze or asthma, and infections of the lower respiratory tract in offspring.

The fish oil used in this last study, however, was a high-quality preparation, the researchers emphasized, warning that users should be cautious when they buy fish oil.

“You really need high-quality, standardized material that’s been processed and stored correctly before comparing results from one study to another study,” Phipps said in a press release. “Our study used the pure, biologically active products in fish oil, known as 17-HDHA, and we’ve provided a clear line of evidence for why intake of high-quality fish oil is good.”

Omega 3 polyunsaturated fatty acids can be found in tuna, salmon, walnuts, flax seed oil, and anchovies.