Heavier smoking increases coffee consumption: findings from a Mendelian randomization analysis

TY - JOUR

T1 - Heavier smoking increases coffee consumption

T2 - findings from a Mendelian randomization analysis

AU - Bjørngaard, Johan H

AU - Nordestgaard, Ask Tybjærg

AU - Taylor, Amy E

AU - Treur, Jorien L

AU - Gabrielsen, Maiken E

AU - Munafò, Marcus R

AU - Nordestgaard, Børge Grønne

AU - Åsvold, Bjørn Olav

AU - Romundstad, Pål

AU - Davey Smith, George

PY - 2017/12/1

Y1 - 2017/12/1

N2 - Background: There is evidence for a positive relationship between cigarette and coffee consumption in smokers. Cigarette smoke increases metabolism of caffeine, so this may represent a causal effect of smoking on caffeine intake.Methods: We performed Mendelian randomization analyses in the UK Biobank ( N  = 114 029), the Norwegian HUNT study ( N  = 56 664) and the Copenhagen General Population Study (CGPS) ( N  = 78 650). We used the rs16969968 genetic variant as a proxy for smoking heaviness in all studies and rs4410790 and rs2472297 as proxies for coffee consumption in UK Biobank and CGPS. 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 (0.16 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 or that the coffee-related variants were associated with cigarette consumption.Conclusions: Higher cigarette consumption causally increases coffee intake. This is consistent with faster metabolism of caffeine by smokers, but could also reflect a behavioural effect of smoking on coffee drinking.

AB - Background: There is evidence for a positive relationship between cigarette and coffee consumption in smokers. Cigarette smoke increases metabolism of caffeine, so this may represent a causal effect of smoking on caffeine intake.Methods: We performed Mendelian randomization analyses in the UK Biobank ( N  = 114 029), the Norwegian HUNT study ( N  = 56 664) and the Copenhagen General Population Study (CGPS) ( N  = 78 650). We used the rs16969968 genetic variant as a proxy for smoking heaviness in all studies and rs4410790 and rs2472297 as proxies for coffee consumption in UK Biobank and CGPS. 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 (0.16 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 or that the coffee-related variants were associated with cigarette consumption.Conclusions: Higher cigarette consumption causally increases coffee intake. This is consistent with faster metabolism of caffeine by smokers, but could also reflect a behavioural effect of smoking on coffee drinking.

KW - Journal Article

U2 - 10.1093/ije/dyx147

DO - 10.1093/ije/dyx147

M3 - Journal article

C2 - 29025033

SN - 0300-5771

VL - 46

SP - 1958

EP - 1967

JO - International Journal of Epidemiology

JF - International Journal of Epidemiology

IS - 6

ER -