Bowel function varies according to age, diet, exercise, and overall health but normal bowel movement frequency seems to be once a day for most people. It stands to reason that an elderly person who consumes less and gets very little exercise will not experience the same frequency of bowl movement as an active young person with a hearty appetite.
Bowel movements are an essential bodily function and it's important to know what is considered normal and abnormal. Abnormal bowel movements include things such as constipation, diarrhea, and colored stools like black or maroon, which are indications of problems in the GI tract. A black or maroon stool could mean internal bleeding. Any serious change in bowel movement frequency and stool color lasting longer than a period of five to seven days could be signs of a medical problem.
Of course there are foods that can change stool color to green, black, and even a reddish color such as spinach, beets, and blueberries which is perfectly normal and no cause for concern. However, if you are eating foods that tend to change the color of your stool, abstain from them for a couple of days to make sure it is indeed the foods causing the color change.
Blood in the stool is never considered to be normal and could be a sign of serious problems. Tarry, sticky, black stools can be caused by something as simple as eating blueberries to something as serious as colon cancer. Bright red (fresh) blood in the toilet is commonly due to things like hemorrhoids which is not particularly serious.
Extremely large, hard stools are generally associated with diet, stress, and putting off bowel movements. Emotional stress can cause stool hardening especially in young people which can lead to complications. An extremely large stool can tear the anus and cause bleeding which could lead to infection. Heavy straining can cause hemorrhoids.
Increasing fiber and fluids in the diet can help but the stress needs to be addressed as well. Something as simple as a bowl of oatmeal each day can go a long way towards eliminating hard stools.
In summary, people vary in age with different eating, exercising, and sleeping patterns along with different digestive cycles. Therefore there is no standard frequency of bowl movement. Frequency of bowel movement depends largely on each person's own digestive system. However, any significant change in stool color that isn't caused by foods and lasts for more than five to seven days should be brought to the attention of your doctor as it could be a sign of an under lying medical condition.