When we talk about natural it is often direct and intriguing. While we use some 'technical terms' or 'jargons', it is better to explain and define those terms then and there as not many people are aware of what you're talking about. Now here, by ingredients you mean urine right? because that's what happens in diuretic effect. You can simply say- Caffeine has a diuretic effect. If you drink a lot of coffee, the caffeine in the coffee produces more urine which results you to pee more.

Caffeine has a diuretic effect. Therefore if you drink a lot of (or excess ) coffee the caffeine therein assists the body to get rid of extra fluid and salt.