Do coffee, tea, and beer truly possess dehydrating properties?

1. Recommendations regarding fluid consumption

2. Indicator of hydration level through beverages

3. Summary

1. Recommendations regarding fluid consumption

The body maintains a constant level of water loss, while fluid intake occurs episodically. Normally, the mechanisms responsible for homeostasis maintain hydration at a constant level, so severe fluid deficits are a rare phenomenon among the majority of the population. Standard imbalances in water balance usually return to normal after 24 hours. The European Food Safety Authority estimates the daily requirement for fluids, i.e., the sum of the water volume from beverages and food, to be around 2 l for women and around 2.5 l for men (at moderate physical activity and moderate environmental conditions). This corresponds to 30–45 ml/kg body weight, e.g., 70 kg × 30 ml = 2100.

2. Indicator of hydration level through beverages

Several factors influence the hydration level, including the frequency of fluid consumption, volume, and composition. The components of individual fluids are metabolized and excreted at different times, affecting gastric emptying and the rate of their absorption in the intestine. Upon reviewing analyses, we can find studies determining the effectiveness of hydration in the context of accelerated regeneration in physically active individuals. In 2016, Prof. Ron Maughan and his colleagues analyzed various fluids available on the market and identified those with the highest hydration efficiency and supporting long-term maintenance of fluid balance. Several beverages with better hydrating properties than water were highlighted, including oral rehydration solutions, skim milk, whole milk, and orange juice. These beverages have significantly more calories and nutrients, which can slow gastric emptying but also lead to greater fluid retention. A surprising fact is that beer, tea, and coffee achieved results very comparable to water, suggesting they do not have dehydrating properties, as often heard.

3. Summary

Choosing the right amount of fluids is a very individual matter. Organizations and scientific societies impose certain guidelines on the amount of fluids we consume. By observing our body, we can choose the right dose of fluids to suit our needs. However, it is important to remember that water should be the basis for hydration, despite the fact that other fluids have been highlighted with equally good or even better properties for irrigation.