Beyond the Brew: Hydration and the Hidden Ingredients in Your Coffee and Tea

Question: Are there any common coffee or tea ingredients I should be mindful of for their impact on hydration levels?

For many, the morning ritual of coffee or the calming afternoon cup of tea is an indispensable part of the day. These beloved beverages are not just sources of comfort and energy; they also contribute significantly to our daily fluid intake. However, delve a little deeper, and you’ll find that the journey from bean or leaf to cup involves a complex interplay of compounds and processes that can subtly influence hydration levels.

The Role of Caffeine and Other Compounds

The most well-known component in coffee and tea is caffeine. Historically, there was a concern that caffeine acted as a diuretic, leading to dehydration. However, modern research suggests that for regular consumers, the body develops a tolerance, and moderate caffeine intake from beverages like coffee does not appear to negatively impact overall hydration [8, 98]. Studies on moderate daily coffee consumption have found no evidence of dehydration [98]. This suggests that the water content in these beverages largely offsets any mild diuretic effect caffeine might have in non-habitual drinkers.

Beyond caffeine, the roasting and processing of coffee beans can influence their chemical composition. For instance, specific volatile compounds contribute to the aroma and flavor of coffee [3, 5]. While these compounds are primarily associated with sensory experiences, understanding the full spectrum of what’s in your cup can provide a more complete picture of its impact. Different coffee species, such as Arabica and Robusta, also possess varying characteristics that might influence their final profile, though direct links to hydration are not extensively detailed in the provided literature [1, 4].

Processing and Preparation Nuances

The way coffee is processed can also play a role. For example, the ‘honey processing’ method, which involves different mucilage retention treatments, impacts the volatile compounds and microbial diversity of Arabica coffee [5]. Similarly, fermentation protocols, whether aerobic or anaerobic, can positively influence parameters like pH and acidity, alongside volatile compound concentrations [3]. While these processes are mainly aimed at enhancing flavor and quality, they highlight the intricate transformations that coffee undergoes before reaching your mug.

For tea, the situation is generally straightforward. Pure tea, whether black or green, is primarily water and offers a hydrating beverage. The presence of compounds like thearubigins in black tea contributes to its characteristic flavor and color [1]. The potential impact on hydration from tea is largely attributed to its water content and the absence of significant dehydrating agents in its natural form.

Beyond the Beverage: Co-products and Additives

While the focus is often on the brewed beverage, it’s worth noting that various parts of the coffee plant, such as cascara (coffee cherry skin), are also utilized. These co-products can have different water activity and pH values compared to the roasted bean itself [4]. In broader contexts, spent coffee grounds have been explored for use in biocomposites, sometimes in conjunction with other ingredients like urea-based plasticizers [2]. While this application is far removed from consumption, it underscores the diverse chemical makeup of coffee by-products.

When considering hydration, it’s also important to think about what might be added to your coffee or tea. Sugars, creamers, and artificial sweeteners can alter the overall nutritional and physiological impact of the beverage. While not intrinsic to coffee or tea, these common additions can influence how your body processes the drink and its contribution to your fluid balance.

In conclusion, while coffee and tea can be considered hydrating beverages for most individuals, especially when consumed in moderation and without excessive additives, a deeper appreciation for their inherent compounds and processing methods reveals a more complex picture. The significant water content generally ensures they contribute positively to fluid intake, with the diuretic effects of caffeine being minimal for regular consumers.

References

[1] — Ernesto Illy, Luciano Navarini — Neglected Food Bubbles: The Espresso Coffee Foam. — 2011-Sep — https://pubmed.ncbi.nlm.nih.gov/21892345/ [2] — Magdalena Zdanowicz, Marta Rokosa, Magdalena Pieczykolan, Adrian Krzysztof Antosik, Katarzyna Skórczewska — Biocomposites Based on Wheat Flour with Urea-Based Eutectic Plasticizer and Spent Coffee Grounds: Preparation, Physicochemical Characterization, and Study of Their Influence on Plant Growth. — 2024-Mar-06 — https://pubmed.ncbi.nlm.nih.gov/38473683/ [3] — Gustavo Galarza, Jorge G Figueroa — Volatile Compound Characterization of Coffee ( — 2022-Mar-21 — https://pubmed.ncbi.nlm.nih.gov/35335365/ [4] — Katarína Poláková, Alica Bobková, Alžbeta Demianová, Marek Bobko, Judita Lidiková, Lukáš Jurčaga, Ľubomír Belej, Andrea Mesárošová, Melina Korčok, Tomáš Tóth — Quality Attributes and Sensory Acceptance of Different Botanical Coffee Co-Products. — 2023-Jul-11 — https://pubmed.ncbi.nlm.nih.gov/37509767/ [5] — Faguang Hu, Haohao Yu, Xingfei Fu, Zhongxian Li, Wenjiang Dong, Guiping Li, Yanan Li, Yaqi Li, Bingqing Qu, Xiaofei Bi — Characterization of volatile compounds and microbial diversity of Arabica coffee in honey processing method based on different mucilage retention treatments. — 2025-Jan — https://pubmed.ncbi.nlm.nih.gov/39974542/ [6] — Rongsuo Hu, Fei Xu, Liyan Zhao, Wenjiang Dong, Xingyuan Xiao, Xiao Chen — Comparative Evaluation of Flavor and Sensory Quality of Coffee Pulp Wines. — 2024-Jun-27 — https://pubmed.ncbi.nlm.nih.gov/38999011/ [7] — Laurentia Fidella Averina Setia Santoso, Kristina Nasr, Adam Maamar Roumani, Hadi Khaled Abou Zeid, Mohammed Shawki Dabbous — Unraveling tea and coffee consumption effects on cardiovascular diseases risk factors: A narrative review. — 2024-Sep — https://pubmed.ncbi.nlm.nih.gov/39323459/ [8] — Ryan C Emadi, Farin Kamangar — Coffee’s Impact on Health and Well-Being. — 2025-Aug-05 — https://pubmed.ncbi.nlm.nih.gov/40806142/