A new study of United Kingdom Biobank participants explored the tie between the consumption of coffee and tea with increased macular retinal nerve fiber layer (mRNFL) thickness.
Let’s talk about coffee and neurodegenerative disorders.
There’s been quite a lot of recent research regarding the benefits of coffee (and tea). Caffeine is well-known as a stimulant, but coffee and tea also include antioxidants such as flavonoids and polyphenols.
Further, coffee and tea drinkers have been shown to have reduced odds of Parkinson’s disease, dementia, as well as type 2 diabetes and stroke.
Now the study.
The UK Biobank, a population-based cohort study of over 500,000 participants from the United Kingdom, collected baseline assessments from participants between 40-69 years of age. A selection of these participants received additional eye examinations including macular optical coherence tomography (OCT).
And the participants?
This study included participants with baseline OCT measurements without ocular disease or high refractive error. Participants were asked in a baseline questionnaire about their daily coffee and tea consumption over the past year in terms of cups per day.
Coffee drinkers were also asked what type of coffee they consumed.
Why focus on the retina?
Thinning of the retinal nerve fiber layer (RNFL) has been shown to be significantly associated with both cognition and neurodegenerative diseases. OCT is a non-invasive way to image the retina and detect brain and vascular disease.
What did they find?
Coffee and tea drinkers had significantly thicker mRNFL than participants who drank no coffee or tea, and mRNFL was thickest among drinkers of 2-3 cups of coffee per day or 4 or more cups of tea per day.
Instant coffee, which was separated in the analysis, was associated with reduced mRNFL thickness.
What else?
The study authors recognized several weaknesses in the study:
- Recall bias due to self-reporting
- No standardization of the OCT examinations, leading to possible measurement errors
- No way to account for subclinical retinal or neurodegenerative disease.
Thus, they urge for further validation in longitudinal studies and clinical trials.
Take home.
Billions of tons of both coffee and tea are consumed globally each year.
These findings support growing evidence linking coffee consumption with reduced risk of various health conditions including neurodegenerative disease.