Once touted as the natural substance that could alleviate many of your chronic ailments and a secret the medical industry didn’t want you to know about, omega-3 fatty acid (n3PUFA) supplements have been on the market for a number of years now and are not quite living up to the hype. Yet, there have been numerous studies to support the use of omega-3s to reduce triglyceride levels as well as anti-inflammatory properties, especially for asthma. Building off the anti-inflammatory data, a team of investigators led by scientists at Duke University wanted to test whether fish oil supplements could improve asthma control in adolescents and young adults with uncontrolled asthma who were overweight or obese.

Findings from the new study—published recently in the Annals of the American Thoracic Society through an article titled “Fish Oil Supplementation in Overweight/Obese Patients with Uncontrolled Asthma: A Randomized Trial”—showed that fish oil a day for six months did not improve asthma control, as measured by a standard asthma control questionnaire, breathing tests, urgent care visits, and severe asthma exacerbations.

“We don’t know why asthma control in obese patients is more difficult, but there is growing evidence that obesity causes systemic inflammation,” explained lead study investigator Jason Lang, MD, associate professor of pediatrics at Duke University. “Because the omega-3 fatty acids in fish oil have anti-inflammatory properties, we wanted to test whether fish oil would have therapeutic benefits for these patients.”

The 98 overweight/obese participants in the study ranged in age from 12 to 25 (average age: 14.6). All were diagnosed with asthma by a physician but had poor asthma control, despite using a daily inhaled corticosteroid to control their asthma. About half the participants were African American. For every three participants assigned to take fish oil for 25 weeks, one was assigned to take the soy oil placebo.

Additionally, the researchers also looked at whether a variant in the gene ALOX5 affected study findings. It is known that mutations in the gene can reduce responses to anti-leukotriene drugs. Leukotrienes are inflammatory molecules that play a critical role in triggering asthma attacks. In this study, the ALOX5 variant did appear to be linked to leukotriene production but not to the effectiveness of fish oil in providing asthma control.

“Omega-3 fatty acid (n3PUFA) supplementation has been proposed as a promising anti-asthma strategy,” the authors wrote. “The rs59439148 ALOX5 polymorphism affects leukotriene production and possibly inflammatory responses to n3PUFA. No studies have assessed n3PUFA supplementation and ALOX5 genotype on asthma control in patients with obesity and uncontrolled asthma.”

Interestingly, the authors wrote that the study’s negative findings may not be the last word on fish oil and asthma, as they acknowledged that larger doses of fish oil over a longer period of time may produce a different result.

Based on the current study, however, “there is insufficient evidence for clinicians to suggest to patients with uncontrolled asthma that they should take daily fish oil supplements to help their asthma,” Lang concluded.