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Do coffee and tea result in dehydration of the organism?
Table of Contents
1. Proper hydration of the body
Water is the most crucial inorganic component of our body. It is responsible for a multitude of functions, including: supporting transformation processes, facilitating the movement of fecal matter, cleansing the body from toxins, transporting organic and inorganic compounds to all cells, and regulating body temperature. Water demand is dependent on various factors such as age, gender, body weight, and fat content in the body. With increased physical activity and higher environmental temperature, the body requires more water due to additional fluid loss through sweat. Due to water's participation in metabolic processes, the need for this nutrient increases with the increased energy value of the diet. A high protein content in the diet may lead to increased diuresis. The amount of water in the body should always remain constant, which means that the water balance must be zero. This means that the amount of water ingested through drinks and food and generated in metabolic processes should equal the amount of water excreted through urine, stool, sweat, and exhaled air.2. Dehydration of the body - symptoms
The human body does not have the capability to store water, which means that a lack of water in the diet quickly leads to dehydration. The first symptoms of dehydration may appear even at a 1% water loss level. In such a case, a decrease in physical performance, reduced ability to regulate body temperature, and loss of appetite may be observed. As dehydration progresses, difficulties in concentration, headaches, drowsiness, restlessness, an increase in body temperature, and breathing rate may occur.3. Dehydration of the body - consequences
Dehydration results in grave health consequences such as: - pain and dizziness, - impairment of cognitive function, motor function, - speech difficulties, - heart rhythm anomalies, - renal insufficiency, - alterations in blood pressure, - constipation, - dry skin, - incorrect medication intake, - diminished saliva secretion.4. Coffee and tea as a source of hydration
Water, various beverages, and food products are sources of fluid for humans. Coffee is the second most commonly consumed beverage by people worldwide. The United States Department of Agriculture (USDA) has published a statement recommending the consumption of fluids without added sugar to reduce their amount in the diet. However, it does not mention diuretic beverages such as coffee and tea. The United States Food and Drug Administration (FDA) recommends that healthy adults consume no more than 400 mg of caffeine per day, which is equivalent to approximately 3-4 cups of coffee.5. Whether coffee and tea have a dehydrating effect
There is a popular myth that coffee and tea have dehydrating properties due to the presence of caffeine. Caffeine is a naturally occurring substance found in coffee, tea, and cocoa. This substance acts as an inhibitor of sodium retention in the renal tubules, and when consumed in large doses (>500 mg) it has a diuretic effect. Early studies conducted by Fisher S. M. and colleagues showed that regular consumption of this substance may contribute to the development of the body's specific tolerance to the substance. Other studies confirm that moderate consumption of caffeine does not lead to significant dehydration of the body. The aim of one of the studies conducted by Grandjean A. and colleagues was to determine the effect of various beverages, including caffeinated ones, on the hydration status of the body. The study involved 18 men aged 24-39 who consumed caffeinated beverages daily, with a total of 624 mg per day. Water loss was assessed by measuring the amount of urine excreted. A decrease in total body water by 2.7% and an increase in urine production by 42% were observed in men. Since the study participants consumed caffeinated beverages daily and completely eliminated caffeine from their diet five days before the study, the results should be interpreted with caution. However, even the authors of the study do not confirm the dehydrating effect of caffeinated beverages. Another experiment conducted by S. C. Killer, A. K. Blannin, and A. E. Jeukendrup did not show any dehydrating properties of coffee. The study involved 50 men who drank 5-6 cups of coffee daily. The study was divided into two trials, each lasting three days. The participants in the study drank 200 ml of coffee, which contained 4 mg of caffeine per kg of body weight, or plain water in the same amount, four times a day. Throughout the study, the physical activity of the participants and the intake of solid food and other fluids were monitored. The hydration status of the body was assessed before and after each trial. The experiment did not show significant differences in the hydration status of the body between coffee consumption and plain water consumption. In the context of the dehydrating effect of coffee and tea, the dosage is crucial. A study by Seal A. D. and colleagues showed that a daily intake of 6 mg of caffeine per kg of body weight can have a diuretic effect, while 3 mg/kg of body weight does not disturb the water balance in the body.6. Comparison of caffeine concentration in coffee and tea
Tea leaves contain 4.5% more caffeine than coffee beans, with a maximum of 2.5% of caffeine. However, during the production of tea the amount of this compound decreases. The level of caffeination in tea depends on the variety, cultivation conditions, degree of fermentation, type and method of brewing. On average, 100 grams of black tea contains 2.8–3.8 mg of caffeine, while 100 grams of green tea contains only 1.0–2.1 mg. The caffeine content in coffee also varies and depends on the type of beans, the production process and the way it is brewed. Robusta coffee contains twice as much caffeine as arabica coffee. The following table shows the average caffeine content in selected coffee and tea beverages. Table 2. Average caffeine content in selected coffee and tea beverages Source: Bojarowicz H. , Przygoda M. , Kofeina. Cz. 1. Powszechność stosowania kofeiny oraz jej działanie na organizm, „Problemy Higieny i Epidemiologii” 2012, 93(1), 8–13.
