Fish oil did not improve asthma control in overweight/obese young people with uncontrolled disease, a new study shows.
It included 98 participants, aged 12 to 25, who had diagnosed asthma but poor asthma control, despite using a daily inhaled corticosteroid.
Obesity causes systemic inflammation
Three-quarters of the participants took four grams of fish oil a day for six months. The others took a soy oil placebo.
Taking fish oil did not improve asthma control, as measured by a standard questionnaire, breathing tests, urgent care visits and severity of symptoms, according to the study recently published online in the journal Annals of the American Thoracic Society.
"We don't know why asthma control in obese patients is more difficult, but there is growing evidence that obesity causes systemic inflammation," study author Dr Jason Lang said in a journal news release. He's an associate professor of paediatrics at Duke University in Durham, North Carolina.
"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," he explained.
Researchers also examined whether a variant in the gene ALOX5 affected the study results. Mutations in the gene can reduce the effectiveness of drugs that target leukotrienes, which are inflammatory molecules that play a major role in triggering asthma attacks.
Researchers said the ALOX5 variant seemed to be connected with leukotriene production but not with the effectiveness of fish oil in providing asthma control.
While future research may find that larger doses of fish oil over a longer period may help control asthma, Lang said this study found "insufficient evidence for clinicians to suggest to patients with uncontrolled asthma that they should take daily fish oil supplements to help their asthma".
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