Caffeine content of brewed teas
Abstract
Caffeine is the world's most popular drug and can be found in many beverages including tea. It is a psychostimulant that is widely used to enhance alertness and improve performance. This study was conducted to determine the concentration of caffeine in 20 assorted commercial tea products. The teas were brewed under a variety of conditions including different serving sizes and steep-times. Caffeine was isolated from the teas with liquid-liquid extraction and quantitated by gas chromatography with nitrogen-phosphorus detection. Caffeine concentrations in white, green, and black teas ranged from 14 to 61 mg per serving (6 or 8 oz) with no observable trend in caffeine concentration due to the variety of tea. The decaffeinated teas contained less than 12 mg of caffeine per serving, and caffeine was not detected in the herbal tea varieties. In most instances, the 6- and 8-oz serving sizes contained similar caffeine concentrations per ounce, but the steep-time affected the caffeine concentration of the tea. These findings indicate that most brewed teas contain less caffeine per serving than brewed coffee.
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Drinking a cup of coffee (107 mg per 250 mL) would likely equate to a 9-min greater reduction in total sleep time than a cup of black tea (47 mg per 250 mL).
“For example, when applying the fi ndings of this study to commonly consumed beverages, drinking a cup of coffee (typical caffeine content: 107 mg per 250 mL [56]) would likely equate to a 9-min greater reduction in total sleep time than a cup of black tea (typical caffeine content: 47 mg per 250 mL [55]).”
From The effect of caffeine on subsequent sleep: A systematic review and meta-analysis (2023) · cites this paper as [55]
One cup of black tea (typical caffeine content: 47 mg per 250 mL) can be consumed up until bedtime without a significant effect on total sleep time.
“one cup of black tea (typical caffeine content: 47 mg per 250 mL [55]) can be consumed up until bedtime without a signi fi cant effect on total sleep time.”
From The effect of caffeine on subsequent sleep: A systematic review and meta-analysis (2023) · cites this paper as [55]
Assuming a 10 p.m. bedtime, there is no clear cut off time for consumption of black tea (typical caffeine content: 47 mg per 250 mL).
“Assuming a 10 p.m. bedtime, there is no clear cut off time for consumption of black tea (typical caffeine content: 47 mg per 250 mL [55]).”
From The effect of caffeine on subsequent sleep: A systematic review and meta-analysis (2023) · cites this paper as [55]
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The effect of caffeine on subsequent sleep: A systematic review and meta-analysis
Gardiner, C., Weakley, J., Burke, L. M., Roach, G. D., Sargent, C., Maniar, N., Townshend, A., & Halson, S. L. (2023) · Sleep Medicine Reviews · doi:10.1016/j.smrv.2023.101764 · Cited by 315 · see citing works
“For example, one cup of black tea (typical caffeine content: 47 mg per 250 mL [55]) can be consumed up until bedtime without a signi fi cant effect on total sleep time.”
BackgroundMethodInfluentialArab, L., Biggs, M. L., O'Meara, E. S., Longstreth, W. T., Crane, P. K., & Fitzpatrick, A. L. (2011) · Journal of Alzheimer's Disease · doi:10.3233/jad-2011-110431 · Cited by 98 · see citing works
- Authors
- Chin, J. M., Merves, M. L., Goldberger, B. A., Sampson-Cone, A., & Cone, E. J.
- Affiliations
- University of Florida (US)
- Corresponding author
- Goldberger, B. A.
- ORCID
- Goldberger, B. A.
- Venue
- Journal of Analytical Toxicology
- Publisher
- Oxford University Press (OUP)
- Published
- 2008-10-01
- Volume
- 32
- Issue
- 8
- Pages
- 702-704
- ISSN
- 0146-4760 (ISSN-L)
- 1945-2403
- OpenAlex
- W2162934205
- Cited by
- 112
- References
- 10
- Citations by year
- 2026: 8 · 2025: 8 · 2024: 9 · 2023: 12 · 2022: 12 · 2021: 6 · 2020: 1 · 2019: 5 · 2018: 8 · 2017: 13 · 2016: 7 · 2015: 2 · 2014: 9 · 2013: 6 · 2012: 2
- FWCI
- 0.94
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Analytical Toxicology (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Pharmacology › Coffee research and impacts
- Health Sciences › Medicine › Pathology and Forensic Medicine › Tea Polyphenols and Effects
- Physical Sciences › Chemistry › Analytical Chemistry › Heavy Metals in Plants
- Keywords
- caffeine, tea beverages, caffeine content, steeping time, serving size, white tea, green tea, black tea, decaffeinated tea, herbal tea, psychostimulants
- MeSH terms
- Caffeine, Chromatography, Gas, Tea
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