Eur J Epidemiol. 2025 Jul 12. doi: 10.1007/s10654-025-01270-5. Online ahead of print. ABSTRACT Faster nicotine metabolism, defined as the nicotine metabolite ratio (NMR), is known to associate with heavier smoking and challenges in smoking cessation. However, the broader health implications of genetically determined nicotine metabolism are not well characterized. We…