According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), about 16 out of 100 adults have symptoms of constipation. About 33 out of 100 adults ages 60 and older have symptoms of constipation. Chronic constipation affects 16 percent of Americans and a third of those older than 602. Constipation is the most common gastrointestinal complaint, resulting in 2.5 million doctor visits annually.