Scientists debunk popular myth about the harm of coffee to the body

Researchers have debunked the widespread myth that coffee dehydrates the body. An experiment involving 50 healthy men who regularly consume caffeine showed that with moderate coffee consumption, hydration levels are virtually no different from those when drinking water. Scientists emphasize that a pronounced diuretic effect is observed only with high doses of caffeine, and in habitual consumers it is less pronounced.

Researchers have debunked the widespread myth that coffee dehydrates the body and requires mandatory compensation with water. An experiment involving 50 healthy men who regularly drink three to six cups of coffee per day showed that with moderate consumption, hydration levels are virtually no different from those when drinking plain water. Scientists at the University of Birmingham conducted an experiment that included two three-day periods: in one, participants drank four 200 ml cups of coffee (an average of about 308 mg of caffeine per day), and in the other, the same amount of water. Researchers tracked total body fluid levels, blood and urine indicators, and changes in body weight. The results showed that coffee had virtually no effect on water balance compared to water. Total body fluid content and daily urine volume remained almost identical, and weight loss did not exceed 0.4 kg and did not indicate dehydration. The only noticeable difference was a slightly greater excretion of sodium in the urine when consuming coffee. The authors concluded that moderate coffee consumption in healthy people accustomed to caffeine can be counted toward total fluid intake. At the same time, the diuretic effect of caffeine is not completely ruled out: according to a meta-analysis, at rest it increases urine output by an average of about 109 ml, but during physical activity this effect is not observed. Researchers also note that a pronounced diuretic effect is usually observed at high doses—about 500 mg of caffeine or more.