The more useful question is how coffee fits into a person's wider health habits. How much do they drink? Do they consume enough water for their needs? Do they have diabetes or hypertension? Are they taking medication that affects kidney function?
These details are far more informative than the simple fact that someone drinks black coffee every morning.
Chapter 2: How Coffee May Affect the Kidneys
The kidneys filter waste products from the blood, regulate fluid balance, and help control blood pressure. Because caffeine can temporarily raise blood pressure in some people, excessive coffee consumption may be worth reviewing for those who already have hypertension.
However, moderate coffee consumption is not generally considered a direct cause of chronic kidney failure. Some observational studies have even associated coffee consumption with a lower risk of developing certain kidney problems, although these findings do not prove that coffee itself provides protection.