Those foods contain omega-3 fatty acids, which are scarce in the typical American diet. Omega-3 fatty acids have also been studied for conditions including heart disease, Alzheimer's disease, and depression.
Japanese doctors put omega-3 fatty acids to the test. They led a two-year study of COPD patients.
They found diets rich in omega-3 fatty acids helped curb COPD. The study appears in Chest.
No. 5 Cause of Death
COPD is the world's No. 5 cause of death, and cases are predicted to rise in coming years, write the researchers.
They included Wataru Matsuyama, MD, PhD. Matsuyama works in the respiratory medicine division of Japan's Kagoshima University Hospital.
Matsuyama's study included 64 COPD patients who hadn't smoked for at least six months.
They also hadn't had a bad flare-up of COPD in at least a month. None was taking antibiotics or nonsteroidal anti-inflammatory drugs.
Dishing Up Omega-3s
The patients were split into two groups. One group was assigned to eat a diet rich in omega-3 fatty acids. The other group got fewer omega-3 fatty acids.
Patients promised not to take omega-3 supplements (such as fish oil or flaxseed oil capsules) on their own. They also wrote down everything they ate for four days per month during the study.
The patients' progress was tracked in two different ways. Their levels of inflammatory chemicals were tracked. They also took six-minute walking tests.
The farther COPD patients can walk in that test, the better their chances of survival tend to be, the researchers note.
Less Inflammation With Omega-3s
People in the omega-3 group had two advantages. They had a significant drop in lung inflammation. They also walked farthest in the six-minute walking test.
The researchers suggest that diets rich in omega-3 fatty acids may be a "safe and practical method for treating COPD."
Since their study was small, they call for bigger, longer studies to check their results.