Summary: New research indicates that excessive coffee consumption may raise the risk of osteoarthritis, other arthropathies and obesity. The study suggests drinking more than six cups of coffee a day could increase the likelihood of adverse health outcomes.
Source: University of South Australia
Coffee is one of the world’s most popular beverages—whether cappuccino, latte or short black—and new genetic research helps clarify when habitual drinking may become harmful. A large, world-first study from the University of South Australia’s Australian Centre for Precision Health examined links between genetically predicted coffee consumption and a wide range of diseases, finding evidence that very high intake is associated with specific harms.
Researchers analysed data from more than 300,000 participants in the UK Biobank to explore causal relationships between habitual coffee intake and health outcomes. Using a Mendelian randomisation phenome-wide association study (MR-PheWAS), the team tested genetic predictors of coffee consumption against 1,117 clinical conditions and followed up notable signals with additional genetic analyses.
Earlier work by Professor Elina Hyppönen and colleagues pointed to six cups of coffee per day as an upper limit for most people. In this larger MR-PheWAS, the researchers found that while moderate coffee drinking appears largely safe, habitual high intake was linked to higher odds of osteoarthrosis (a form of osteoarthritis), other arthropathies (joint diseases) and being overweight or obese.
Professor Elina Hyppönen, an expert in genetic epidemiology at UniSA, explains the public health significance: “With around three billion cups of coffee consumed worldwide each day, understanding both benefits and risks of habitual coffee intake matters for population health. Observational studies can be affected by confounding and reverse causation, so we used a genetic approach to better estimate causal effects.”
The MR-PheWAS method uses genetic variants associated with habitual coffee consumption to reduce bias that commonly affects traditional observational analyses. This approach allowed the team to screen many disease outcomes and then apply Mendelian randomisation to evaluate whether associations are likely to be causal.
Key findings:
- Moderate coffee consumption generally showed no substantial harm in this study population.
- Genetic evidence suggested increased odds of osteoarthrosis and other arthropathies among those with genetically instrumented higher coffee intake.
- Higher habitual coffee consumption was also associated with increased odds of overweight and obesity.
- The study did not support a causal harmful association for some initially flagged conditions once pleiotropy and other biases were accounted for.
“For people with a family history of joint disease or who are concerned about developing osteoarthritis or arthritis, these findings are a cautionary signal,” Professor Hyppönen says. “The body often signals when a habit is not agreeing with it, and individuals should pay attention to symptoms. Overall, moderation remains the safest guidance: enjoy coffee, but avoid excessive daily intake.”
Notes on prevalence
- Arthropathy, commonly expressed as arthritis, affects an estimated one in seven Australians and tens of millions of adults worldwide.
- Osteoarthritis, a chronic degenerative joint disease that often affects hands, spine, hips, knees and ankles, is estimated to affect roughly one in eleven Australians and hundreds of millions of people globally.
- Obesity continues to rise worldwide: nearly 40% of adults are overweight and about 13% are obese. In Australia, approximately two-thirds of adults are overweight or obese.
About this research
Source: University of South Australia
Media contact: Annabel Mansfield – University of South Australia
Original research: “Association between habitual coffee consumption and multiple disease outcomes: A Mendelian randomisation phenome-wide association study in the UK Biobank.” Authors: Konstance Nicolopoulos, Anwar Mulugeta, Ang Zhou, Elina Hyppönen. Published in Clinical Nutrition. (Closed access.)
Abstract (summary)
Background:
Coffee is the most commonly consumed beverage after water, yet debate continues over its net effects on health. Much of the existing evidence is observational and therefore vulnerable to confounding and reverse causation.
Methods:
This MR-PheWAS used data from up to 333,214 participants of White-British ancestry in the UK Biobank. The researchers built a genetic risk score for habitual coffee consumption and screened for associations across 1,117 case-control disease series. Signals passing a strict false discovery threshold were followed up with Mendelian randomisation and, where feasible, replication in independent resources.
Results:
The phenome-wide scan initially identified 13 signals across five disease groups. The strongest association was seen for gout, but further analyses indicated pleiotropy and did not support a causal link. Robust MR evidence of a possible causal relationship with habitual coffee consumption was obtained for four distinct outcomes: increased odds of osteoarthrosis, increased odds of other arthropathies, increased odds of overweight/obesity, and decreased odds of postmenopausal bleeding. Phenotypic associations based on self-reported coffee intake broadly supported these findings for the four outcomes.
Conclusions:
This large-scale MR-PheWAS found little evidence of broad harms or benefits from higher habitual coffee consumption. The clearest evidence for harm in this genetic analysis concerned osteoarthrosis, other arthropathies and obesity. These results suggest moderation in coffee intake is a prudent public-health message.
Note: This summary is based on the cited research and university release. It aims to present the study’s methods and findings in clear language without adding new or unverified claims.