Netherlands: Study on Caffeine Intake and Health

Mendelian randomization analyses suggest that genetically determined higher intake of caffeine does not protect against type 2 diabetes (T2D) or coronary artery disease (CAD), according to a recent study. This is in contrast to observational analyses demonstrating the protective role of caffeine against heart disease and diabetes.

The findings of the study are published in the Journal of the American Heart Association.

Caffeine, readily available in coffee, tea, and other food products, is the most widely consumed psychostimulant. Previous observational studies and meta‐analyses have reported caffeine intake to be associated with lower risk of CAD and T2D. However, whether these associations are causal is not known. Therefore, Pim van der Harst, University Medical Center Utrecht, Utrecht, The Netherlands, and colleagues aimed to identify genetic variants associated with caffeine intake, and to investigate evidence for causal links with CAD or T2DM. Also, they aimed to replicate previous observational findings.

For the purpose, the researchers tested observational analyses within UK Biobank using Cox regression analyses. Next, genome‐wide association studies were performed on self‐reported caffeine intake from coffee, tea, or both in 407,072 UK Biobank participants.

Key findings of the study include:

• Moderate observational caffeine intakes from coffee or tea were associated with lower risks of CAD or T2D, with the lowest risks at intakes of 121 to 180 mg/day from coffee for CAD (hazard ratio [HR], 0.77), and 301 to 360 mg/day for T2DM (HR, 0.76).
• These analyses identified 51 novel genetic variants associated with caffeine intake at P<1.67×10⁻⁸.
• These loci were enriched for central nervous system genes.
• In contrast to the observational analyses, 2‐sample Mendelian randomization analyses using the identified loci in independent disease‐specific cohorts yielded no evidence for causal links between genetically determined caffeine intake and the development of CAD or T2D.

"Mendelian randomization analyses indicate genetically determined higher caffeine intake might not protect against CAD or T2DM, despite protective associations in observational analyses," wrote the authors.

"Our data do not support recommending caffeine intake to protect against the development of coronary artery disease or type 2 diabetes mellitus," they concluded.

The study, "Associations of Observational and Genetically Determined Caffeine Intake With Coronary Artery Disease and Diabetes Mellitus," is published in the Journal of the American Heart Association.

DOI: https://www.ahajournals.org/doi/full/10.1161/JAHA.120.016808