New Delhi: The way coffee is brewed may influence healthy ageing, according to a new study published in npj Science of Food. Researchers analysing health data from nearly 50,000 adults found that drinking filtered coffee was associated with markers of slower biological ageing, while instant coffee consumption was linked to markers associated with faster biological ageing.
However, the researchers stressed that the findings show an association, not a cause-and-effect relationship. They cautioned that lifestyle, diet, genetics and other health factors may also influence the results, and further research is needed before making changes to dietary recommendations.
What is biological ageing?
Unlike chronological age, which simply refers to the number of years a person has lived, biological age reflects how well the body’s cells, tissues and organs are functioning.
People of the same age can have different biological ages depending on factors such as:
- Genetics
- Diet
- Physical activity
- Sleep
- Environmental exposures
- Chronic health conditions
Scientists increasingly use biological ageing markers to estimate an individual’s overall health and future risk of age-related diseases.
For this study, researchers evaluated biological ageing using three established measures:
- Relative leukocyte telomere length (rLTL): Shorter telomeres are generally linked to ageing and chronic diseases.
- PhenoAge Acceleration (PhenoAgeAccel): A biological age estimate based on clinical biomarkers.
- Klemera-Doubal Method Biological Age Acceleration (KDM-BAAccel): Another recognised indicator of biological ageing.
Study analysed nearly 50,000 adults
Researchers examined dietary and health information from 49,414 participants enrolled in the UK Biobank, with an average age of 56.4 years.
Participants reported their coffee consumption through repeated dietary questionnaires, while biological ageing markers were assessed using blood tests and clinical measurements.
After accounting for factors including smoking, body mass index (BMI), alcohol consumption, physical activity, diabetes, cardiovascular disease and whether participants added milk or sugar to coffee, the researchers observed notable differences between brewing methods.
Filtered coffee linked with healthier ageing markers
The study found that people who regularly drank filtered coffee generally had:
- Lower biological age acceleration scores.
- Longer telomeres, indicating healthier cellular ageing.
- More favourable ageing biomarkers overall.
In contrast, instant coffee consumption was associated with:
- Higher biological age acceleration scores.
- Shorter telomeres.
- Biomarkers linked to faster biological ageing.
Other brewing methods did not show consistent associations.
Why could filtered coffee be different?
The researchers did not determine why filtered coffee appeared to have more favourable associations but proposed several possible explanations.
Filtered coffee contains numerous bioactive compounds, including:
- Chlorogenic acids
- Polyphenols
- Caffeine
- Antioxidants
Previous research has linked these compounds to reduced inflammation, improved insulin sensitivity and better cardiovascular health.
The study also suggested that inflammation and metabolic health may partly explain the observed associations.
Researchers identified biomarkers such as cystatin C, basal metabolic rate (BMR) and glycoprotein acetylation (GlycA) as potential mediators.
Earlier studies have also shown that brewing methods affect coffee’s chemical composition.
According to the European Society of Cardiology, unfiltered coffee contains higher levels of cafestol and kahweol, compounds that can increase LDL (“bad”) cholesterol. Paper filters remove much of these substances during brewing.
Does this mean instant coffee is unhealthy?
The researchers emphasised that the observed differences were relatively modest.
Most estimates corresponded to only 0.1 to 0.2 years of biological age acceleration, making the findings statistically significant but of uncertain clinical importance for individuals.
Importantly, the study was cross-sectional, meaning it cannot establish that one type of coffee causes faster or slower ageing.
People who drink filtered coffee may differ from instant coffee drinkers in other important ways, such as diet quality, socioeconomic background, sleep habits and healthcare access, despite statistical adjustments.
What previous research says
Coffee remains one of the world’s most extensively studied beverages.
According to the World Health Organization (WHO) and several large observational studies, moderate coffee consumption has generally been associated with lower risks of conditions such as:
- Type 2 diabetes
- Cardiovascular disease
An umbrella review published in The BMJ also found that consuming around three to four cups of coffee daily was generally associated with more health benefits than harms for most adults.
However, excessive caffeine intake may increase anxiety, disturb sleep and may not be suitable for pregnant women or people with certain heart rhythm disorders.
Researchers urge caution
The authors highlighted several limitations of the study:
- It was observational and cannot prove cause and effect.
- Coffee intake was self-reported, which may introduce recall bias.
- Most participants were of White European ancestry, limiting wider applicability.
- Residual confounding from unmeasured lifestyle factors cannot be ruled out.
- The study assessed biological ageing markers rather than lifespan or disease outcomes.
Researchers said long-term prospective studies and clinical trials are needed before recommending one brewing method over another specifically for healthy ageing.
For now, experts continue to emphasise that healthy ageing depends primarily on an overall healthy lifestyle, including a balanced diet, regular exercise, adequate sleep and avoiding tobacco, rather than any single food or beverage.
