Modern day research has shown many health benefits of coffee, including reducing the risk of Alzheimer's, lowering the risk of type 2 diabetes, and supporting heart health. But does coffee hydrate you?
Although caffeine flushes the kidneys and eliminates fluid, it doesn't actually lead to dehydration. That's because you are absorbing fluids from coffee. Since the body naturally absorbs the fluid you need it can be argued that coffee consumption should count toward the necessary daily amounts of water. That amount varies but the Institute of Medicine generally advocates 9 to 13 cups of water daily.
Healthline did a study in which coffee drinkers drank predetermined amounts of plain water, low-caffeine coffee, and high-caffeine coffee. The goal was to identify signs of dehydration based on caffeine content versus water alone. Study results, as published by Frontiers in Nutrition, concluded that both water and low-caffeine coffee were hydrating resources, while high-caffeine coffee produced a short-term diuretic effect.
Another study published by the journal, Plos One, looked at 50 "coffee habituated" males who consumed three to six cups per day. It confirmed that drinking moderate amounts of coffee did not lead to dehydration but provided similar hydration effects to water.
I wouldn't replace your daily water intake with coffee, but I would say that coffee adds to your hydration. As always, we should aim for moderation including moderation. Another great benefit of the