Coffee Coffee and other caffeinated drinks for example, caffeinated energy drinks and even soft drinks. According to figures, 12 ounce of soft drinks contains between 23 and 69 milligrams of caffeine. Now, while caffeine can act as a stimulant for bowel movement it can also cause a person dehydration. A large dose of caffeine can increase the flow of blood to the kidneys to stop the absorption of sodium by acting as a diuretic. So this is bad news for the people out there who need coffee to function. Coffee has become a part of our very lifestyle. The best way to stay hydrated is to drink as much water possible. Its non- caffeinated, inexpensive and also readily available. The minimum requirement for water is 3 litres. If you take flax seeds along with warm water early in the morning, it will really help you cure constipation.