To understand constipation, you have to understand how the large intestine creates feces (stool). Food flows through the small intestine as a liquid mixture of digestive juices and the food you eat. By the time it reaches the large intestine, all the nutrients have been absorbed. The large intestine has one main function: to absorb water from the waste liquid, and turn it into a waste solid (stool).
Common Causes
Sometimes too much water is absorbed by the large intestine, leaving a very hard and dry stool that can't be passed without straining. That's constipation. Constipation itself is unpleasant enough, but when compounded by hemorrhoids created from straining, it can be miserable. Listed below are some common causes of constipation.
Not drinking enough fluids. Your colon will absorb more water to prevent dehydration, resulting in dry, hard stools.
Not having a bowel movement when you have the urge. This keeps stool in the colon longer, where more water is absorbed and stools get harder.
Anything slowing movement of food through your colon increases your risk for constipation. Again, the longer it stays in, the harder it gets. Common factors slowing down the colon:
Being inactive
Not eating enough fiber
Not eating regularly enough to stimulate the intestines to move food along
Certain high-protein foods
Many drugs
Rules to prevent constipation
Eat three meals per day at least 4 hours apart. Frequent feeding keeps your intestines contracting and moving stool along.
Drink at least 32 oz. (one quart) of water per day, not including what you drink at meal time.
Avoid caffeine and alcohol, which deplete body water stores. If you can't avoid these, then match your caffeinated or alcoholic beverage intake with an equal amount of water.
If your diet is not extremely high in fruits, vegetables, and whole grains, by all means take a bulk fiber supplement
http://quickcare.org/gast/constipation.html