Hi,
Nicotinamide Riboside (NR) is a form of vitamin B3, (niacin). A 2024 clinical trial showed that NR supplementation (2 g/day for 6 weeks) reduced airway inflammation in COPD patients with effects lasting 12 weeks post-treatment. It also boosted NAD+ levels, which may support lung function and slow cellular aging. Early research suggests NR may reduce fatigue and improve mitochondrial function, potentially easing symptoms like breathlessness. The 500 mg dose you mentioned is lower than the 2 g (2000 mg) used in the COPD trial but aligns with common supplement doses (250–1000 mg/day) for general health. Doses up to 2000 mg/day are generally safe, with mild side effects like nausea or bloating.

All-Trans Retinoic Acid (ATRA) is a derivative of vitamin A (retinoic acid) used in prescription medications like tretinoin for acne or leukemia treatment. It regulates cell growth and has been studied for its potential to repair lung tissue. Animal studies (e.g., mice) suggest ATRA at doses equivalent to 10 mg in humans may promote alveolar regrowth (up to 20% improvement in lung tissue) by stimulating Wnt signaling and stem cell activity, which could theoretically help repair emphysema-related damage. But, human studies are limited, and ATRA’s role in COPD treatment is experimental. ATRA can cause serious side effects, including liver toxicity, dry skin, and increased sensitivity to sunlight. Human trials for COPD are 5–10 years away.

I hope that answers your question.
As always, talk to your doctor before taking any of these supplements.