Answer:
Tomatoes and beets can turn your stools red. Other possibilities include blueberries, licorice, iron supplements, Pepto-Bismol--all of these can turn your stools black, which looks a lot like blood in your stools.
The most common causes of bright red blood in your poop are hemorrhoids and anal fissures. Hemorrhoids can begin to bleed when you strain during a bowel movement or even when you wipe a little too roughly. Anal fissures are also quite sensitive to straining and may cause you to have bloody poop. If this is the cause of your problem, the doctor will probably encourage you to drink more fluids and deal with any possible causes of constipation. Another remedy that will provide great results is a colon cleanse. Natural colon cleaners help to remove old waste matter that may be contributing to your constipation.