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BMJ Medicine
Research
Appraisal of the causal effect of plasma caffeine on adiposity, type 2 diabetes, and cardiovascular disease: two sample mendelian randomisation study

Abstract

Objective To investigate the potential causal effects of long term plasma caffeine concentrations on adiposity, type 2 diabetes, and major cardiovascular diseases.

Design Two sample mendelian randomisation study.

Setting Genome-wide association study summary data for associations of two single nucleotide polymorphisms associated with plasma caffeine at the genome-wide significance threshold (rs2472297 near the CYP1A2 gene and rs4410790 near the AHR gene) and their association with the outcomes.

Participants Primarily individuals of European ancestry participating in cohorts contributing to genome-wide association study consortia.

Main outcome measures Outcomes studied were body mass index, whole body fat mass, whole body fat-free mass, type 2 diabetes, ischaemic heart disease, atrial fibrillation, heart failure, and stroke.

Results Higher genetically predicted plasma caffeine concentrations were associated with lower body mass index (beta −0.08 standard deviation (SD) (95% confidence interval −0.10 to −0.06), where 1 SD equals about 4.8 kg/m2 in body mass index, for every standard deviation increase in plasma caffeine) and whole body fat mass (beta −0.06 SD (−0.08 to −0.04), 1 SD equals about 9.5 kg; P<0.001) but not fat-free mass (beta −0.01 SD (−0.02 to −0.00), 1 SD equals about 11.5 kg; P=0.17). Higher genetically predicted plasma caffeine concentrations were associated with a lower risk of type 2 diabetes in two consortia (FinnGen and DIAMANTE), with a combined odds ratio of 0.81 ((95% confidence interval 0.74 to 0.89); P<0.001). Approximately half (43%; 95% confidence interval 30% to 61%) of the effect of caffeine on type 2 diabetes was estimated to be mediated through body mass index reduction. No strong associations were reported between genetically predicted plasma caffeine concentrations and a risk of any of the studied cardiovascular diseases.

Conclusions Higher plasma caffeine concentrations might reduce adiposity and risk of type 2 diabetes. Further clinical study is warranted to investigate the translational potential of these findings towards reducing the burden of metabolic disease.

WHAT IS ALREADY KNOWN ON THIS TOPIC
Small, short term trials have shown that caffeine intake results in weight and fat mass reduction, but the long term effects of caffeine intake is unknown

Consumption of coffee, a rich source of caffeine, is observationally associated with a lower risk of type 2 diabetes and cardiovascular disease

WHAT THIS STUDY ADDS

Genetically predicted, lifelong, higher plasma caffeine concentrations were associated with lower body mass index and fat mass, as well as a lower risk of type 2 diabetes

Approximately half of the effect of caffeine on type 2 diabetes was estimated to be mediated through body mass index reduction

HOW MIGHT THIS STUDY AFFECT RESEARCH, PRACTICE, OR POLICY

Long term clinical studies investigating the effect of caffeine intake on fat mass and type 2 diabetes risk are warranted

Tuloksista käy ilmi, että kofeiini paransi univajeisten osallistujien huomiokykyä niin paljon, että se oli samalla tasolla kuin nukkuneiden ryhmään kuuluvilla, kertoo PsyPost.

Kun yönsä nukkuneille annettiin kofeiinia, huomattiin, että se paransi myös heidän huomiokykyään.

Kofeiini ei kuitenkaan vähentänyt virheitä tehtävissä, joissa piti suorittaa tietyt vaiheet oikeassa järjestyksessä toistamatta mitään edellisistä vaiheista. Sama tulos nähtiin sekä nukkuneiden että univajeisten ryhmässä.

Tutkijoiden mukaan tulokset tarkoittavat yksinkertaistetusti sitä, että jos ihminen on univajeinen, kofeiini voi auttaa tätä pysymään hereillä ja pelaamaan älypuhelimella, mutta se ei todennäköisesti auttaisi tekemään hyvää suoritusta esimerkiksi matematiikan kokeessa.