Coffee and Tea Consumption Linked to Increased Macular Retinal Fiber Layer Thickness

by | Jun 19, 2023 | 2023, Caffeine, Eye Health

Written by Taylor Woosley, Staff Writer. Findings of the cross-sectional study including 35,557 participants shows that both coffee and tea consumption are significantly associated with mRNFL thickness. The association was significant for subjects consuming 2-3 cups of coffee a day and for those consuming ≥4 cups of tea per day. 

cup of coffeeCoffee and tea are two of the most widely consumed beverages in the world and are popular sources of dietary caffeine1. Caffeine blocks adenosine receptors and exerts beneficial effects on neuroinflammatory, neuromodulatory, and neuroprotective processes2. Furthermore, epigallocatechin gallate (EGCG) and chlorogenic acid (CGA) are major components of green tea and coffee polyphenols and are believed to aid cognitive function and memory3.

The retina, being an extension of the brain, may reflect pathological processes occurring in the brain4. Consequently, the eye is vulnerable to similar processes that are associated with neurodegenerative diseases5. Research has shown retinal ganglion cell degeneration and retinal nerve fiber layer (RNFL) depletion in subjects with dementia6.

Yuan et al. conducted a cross-sectionally designed study to investigate associations between self-reported coffee and tea consumption with OCT-measured macular retinal nerve fiber layer (mRNFL) thickness in a subgroup of UK Biobank participants. All subjects were between the ages of 40-69 years and had participated in a baseline visit (2006-2010) and completed questionnaires, interviews, physical measurements, and blood and urine assays. Daily coffee and tea consumption was divided into four categories: 0 cup/day, 0.5-1 cups/day, 2-3 cups/day, and ≥4 cups/day.

A subgroup of participants received additional eye examinations (intraocular pressure, autorefraction, visual acuity, and macular OCT at baseline). Eye examinations were performed on both eyes at six assessment centers by trained technicians using the same model of OCT devices. Average mRNFL thickness was analyzed across six subfields (superior, superior-temporal, superior-nasal, inferior, inferior-nasal, and inferior-temporal). Demographic, socioeconomic, lifestyle, and health-related covariates were included to control for potential confounding variables. Student t-tests, Chi-square tests, and analyses of variance analyzed categorical and continuous characteristics among participants with differing frequency of coffee and tea consumption. Multivariable linear regression models evaluated the association of coffee and tea consumption with average mRNFL thickness after adjusting for lifestyle, medical factors, and ocular parameters.

35,557 participants were included in the final analysis. Coffee was consumed by 78% of subjects and tea was consumed by 86% of participants. Significant findings of the study are as follows:

  • Coffee consumption was significantly associated with an increased mRNFL thickness (β = 0.13, 95% CI = 0.01~0.25). However, the association with mRNFL thickness was only significant in those who drank 2~3 cups of coffee per day (β = 0.16, 95% CI = 0.03~0.30).
  • RCS models supported these findings, with an inverted U-shape association noted between coffee drinking and mRNFL thickness (p for non-linear = 0.01). Sensitivity analyses show associations between coffee consumption and mRNFL thickness was not affected by age and gender (p > 0.05).
  • Tea consumption was associated with an increased mRNFL thickness (β = 0.17, 95% CI = 0.04~0.29), particularly in subjects who consumed ≥4 cups of tea per day (β = 0.16, 95% CI = 0.01~0.30).
  • The RCS model shows that mRNFL thickness linearly increased with tea intake (p for non-linear = 0.29). Sensitivity analysis indicated associations between tea consumption and mRNFL thickness were not affected by age and gender groups (p > 0.05).

Results of the study show that coffee and tea consumption is associated with increased mRNFL thickness. These findings were significant in subjects consuming 2~3 cups of coffee per day and 4 or more cups of tea a day. Further research should continue to explore the neuroprotective potential of coffee and tea consumption. Study limitations include the cross-sectional study design which limited casual inference and the potential for recall bias regarding questionnaire answers.

Source: Yuan, Yixiong, Gabriella Bulloch, Shiran Zhang, Yanping Chen, Shaopeng Yang, Wei Wang, Zhuoting Zhu, and Mingguang He. “Consumption of Coffee and Tea Is Associated with Macular Retinal Nerve Fiber Layer Thickness: Results from the UK Biobank.” Nutrients 15, no. 5 (2023): 1196.

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Posted June 19, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

References:

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