What are the main causes of chronic constipation? how can someone from choric constipation (with no bleeding or pain) correct this condition?

Habit/diet. Constipation occurs when feces remain too long in the large intestine and moisture is extracted by that organ. Some foods like breads, bananas, rice, among others are more constipating. More dietary fiber, hydrating foods, juices, loosen stools. Emptying more often, whether the need is felt or not, prevents excess drying/constipation.

You may take a fiber laxative like Metamucil and drink enough water daily so that your urine is colorless. For the long term you may try to increase your intake of fiber foods. Consult this site for fiber foods. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/high-fiber-foods/art-20050948 Wish you good health!