RT Journal Article
SR Electronic
T1 Cigarette smoking increases coffee consumption: findings from a Mendelian randomisation analysis
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 107037
DO 10.1101/107037
A1 Johan H Bjørngaard
A1 Ask Tybjærg Nordestgaard
A1 Amy E Taylor
A1 Jorien L Treur
A1 Maiken E. Gabrielsen
A1 Marcus R Munafò
A1 Børge Grønne Nordestgaard
A1 Bjørn Olav Åsvold
A1 Pål Romundstad
A1 George Davey Smith
YR 2017
UL http://biorxiv.org/content/early/2017/02/08/107037.abstract
AB Background Smokers tend to consume more coffee than non-smokers and there is evidence for a positive relationship between cigarette and coffee consumption in smokers. Cigarette smoke increases the metabolism of caffeine, so this association may represent a causal effect of smoking on caffeine intake.Methods We performed a Mendelian randomisation analysis in 114,029 individuals from the UK Biobank, 56,664 from the Norwegian HUNT study and 78,650 from the Copenhagen General Population Study. We used a genetic variant in the CHRNA5 nicotinic receptor (rs16969968) as a proxy for smoking heaviness. Coffee and tea consumption were self-reported. Analyses were conducted using linear regression and meta-analysed across studies.Results Each additional cigarette per day consumed by current smokers was associated with higher coffee consumption (0.10 cups per day, 95% CI:0.03,0.17). There was weak evidence for an increase in tea consumption per additional cigarette smoked per day (0.04 cups per day, 95% CI:-0.002,0.07). There was strong evidence that each additional copy of the minor allele of rs16969968 (which increases daily cigarette consumption) in current smokers was associated with higher coffee consumption (0.15 cups per day, 95% CI:0.11,0.20), but only weak evidence for an association with tea consumption (0.04 cups per day, 95% CI:- 0.01,0.09). There was no clear evidence that rs16969968 was associated with coffee or tea consumption in never or former smokers.Conclusion These findings suggest that higher cigarette consumption causally increases coffee intake. This is consistent with faster metabolism of caffeine by smokers, but may also reflect behavioural links between smoking and coffee.