Overall, there is no strong evidence that certain dietary supplements improve lung-function in COPD. Small clinical studies show that taking 80-140 milliliters of nitrate-rich beet-root juice for 1-2 weeks, 300 milligrams of chlorella extract daily for 8 weeks, or 20 milligrams of Tualang honey daily for 6 months does not improve lung function or measures in people with COPD.[1] Although beetroot juice does not seem to improve lung function in COPD, it may improve physical function. Two small clinical studies in adults with COPD show that drinking 140 milliliters of nitrate-rich beetroot juice daily for 2 weeks, or twice weekly for 8 weeks, increases the total distance walked on the incremental shuttle walk test (ISWT) when compared to no intervention.[2][3]
One small clinical study conducted in Egypt suggests that adding black seed (or black-seed) oil to standard therapy (corticosteroids and bronchodilator inhalers) might have modest benefits in COPD, possibly due to black seed’s anti-inflammatory and antioxidant effects. Adults with COPD who took 1 gram of black seed oil (containing at least 0.95% thymoquinone) capsules two times daily for 3 months had modestly increased expiratory flow compared to those receiving standard treatment only.[4][1]