Abstract:
Tobacco smoking and coffee consumption are two modifiable lifestyle factors relevant to global health that are also strongly associated with each other. Although moderate coffee consumption alone may confer some health benefits, its combination with tobacco may paradoxically exacerbate tobacco-related harms. To date, observational studies have reported contradictory findings on the causal link between tobacco smoking and coffee intake when relying on self-reports that are prone to bias since sociocultural practices and products consumed vary widely between countries.
Herein, we investigate tobacco smoke and coffee co-exposures in a sub-cohort of the Prospective Urban Rural Epidemiological (PURE) study (n=5,000; 14 countries) using high-throughput multisegment capillary electrophoresis-mass spectrometry in positive and negative ion modes. A targeted analysis of the seven urinary nicotine metabolites (i.e., total nicotine equivalent) was used to verify tobacco smoke exposures, whereas nicotine metabolizers were classified based on the nicotine metabolic ratio as an indicator of their nicotine dependence. Untargeted metabolite analyses was also performed to identify specific urinary biomarkers associated with coffee consumption distinct from other caffeinated beverages, including tea and soda. Untargeted profiling identified population-generalizable coffee biomarkers, validated for selectivity, dose-response, association strength, and precision. A panel of urinary biomarkers of coffee intake generalizable to diverse populations in PURE were then validated based on several criteria, including selectivity, association strength, dose-response, and precision.
For the first time, we report striking sex- and regional variations in active/secondhand smoke exposures across country income groups, not reliably captured by self-reports in PURE. Further, fast nicotine-metabolizing female smokers had the highest coffee intake, exceeding age/BMI-matched males and non-smoking females, as confirmed by robust urinary biomarkers of coffee intake. This work may help guide more effective smoking cessation strategies for chronic disease prevention among high-risk female smokers.