Answers to 7 FAQs

From diet to disease, many things affect your poop. If you have any concerns that your stool is abnormal, then visit your physician.

1. What is poop made of?

In a typical bowel movement, about 75% of the stool volume is water. The other 25% is a mixture of things, primarily dead and living bacteria, food waste, as well as undigested parts of foods, typically fibrous foods such as seeds, nuts, corn, and beans, and substances contributed by the intestines and liver, such as mucus and bile (a dark green to yellowish-brown fluid). Many things can affect the balance of stool content, including diet, medications, supplements, and the presence of a GI disease, disorder, or infection.

2. What is a healthy bowel movement?

An ideal stool is medium-brown, long, smooth, and soft, which passes easily from the body with little straining or effort. Healthy individuals typically have bowel movements anywhere between three per day and three per week. More than three per day is often associated with diarrhea, and fewer than three per week typically suggests constipation, although there must be other symptoms present before the stool strictly qualifies as either diarrhea or constipation. Ideal stool requires little effort and no straining for elimination.

3. What does the colour of my poop mean?

Brown: Healthy bowel movements tend to be brown, due to the presences of bile and bilirubin, which is a product resulting from dead red blood cells being broken down in the intestine.

Black: If your stool is black, it is important to see your doctor, as it could be a sign of internal bleeding from higher in the digestive tract, especially if it smells foul and is tarry. However, there are many benign causes of black stool, including ingesting something with bismuth subsalicylate such as Pepto-Bismol® (which can also turn your tongue black), iron supplements, black liquorice, blueberries, or other darkly coloured foods.

Red or Maroon: If you are bleeding in the lower portion of the digestive tract, then this could cause bright red stool. Bleeding could be a result of inflammatory bowel disease, diverticulitis, hemorrhoids, fissures, polyps, or colorectal cancer. However, a red stool might be unrelated to bleeding, since consuming large amounts of foods with red colouring, such as cakes or colourful packaged breakfast cereals, tomato-based sauce and soup, and beets can also colour your stool red.

Orange: If you consume excess beta-carotene from supplements or produce, such as carrots, sweet potato, squash, some leafy greens, and some herbs, then your stool can appear orange.

Yellow/Pale Brown/Grey: Bright yellow diarrhea can signify a condition known as Giardiasis (see sidebar). Stool that is yellow or pale can also result from reduced production of bile salts, since a normal, brown-coloured stool acquires its hue from breaking down bile. Pale stool (yellow or grey) can signify a problem with the liver or gallbladder, so if you have persistently light-coloured stool, then you should see your physician.

Green: Most often, green stool is the result of ingesting large quantities of green foods, such as leafy greens or foods with green colouring added. Iron supplements may also cause the stool to become green. However, green stool could also signify a colonic transit time that is too fast. Bile usually becomes darker as it passes through the large intestine but stays green if it moves through too quickly.

Blue: Eating lots of blue foods (e.g., blueberries) or beverages with blue food colouring (e.g., grape pop) can turn your stool this colour.

4. Is the texture of my bowel movement normal?

The Bristol Stool Chart is the most useful tool developed for assessing the texture and shape of your stool. On a scale of 1-7, you rate your stool on how solid or liquid it is. For instance, small, hard lumps that are difficult to pass would be a 1, and entirely liquid would be a 7. On this scale, 1-2 could signify constipation, 3-5 are healthy stools, and 6-7 point to diarrhea.

5. Why do some stools float and others sink?

Most stool sinks because the contents of feces tend to be denser than water. However, some stool just floats and, generally, this is nothing of concern, as it is usually the result of gas within the fecal matter, or a high fibre intake. Excess fat in the stool (steatorrhea) can also cause feces to float. This is especially common in individuals who have GI conditions that affect fat absorption, such as celiac disease or Crohn’s disease, but can also happen in healthy individuals who consume large quantities of fat, which is likely the cause if the stool is also oily and foul smelling.

6. Why does it hurt when I have a bowel movement?

There are many reasons why defecation might cause pain. Depending on the type and severity of the pain, it could be anything from what you ate to an irritated hemorrhoid. In rare cases, a tumour in the intestine could make bowel movements painful. If you have any concerns about persistent pain, see your physician. Here are some common causes:

  • Constipation is the most common cause of pain; if your stools are hard and difficult to pass, this could be the culprit
  • Diarrhea can also cause cramping, leading up to elimination
  • If you eat too much spicy food, the oils can stay in your stool and cause burning upon defecation, in the same way that they can make your mouth burn when you eat them
  • Hemorrhoids, anal fissures (tears in the anus), and abscesses can cause pain and bleeding
  • Bowel conditions, such as irritable bowel syndrome, celiac disease, inflammatory bowel disease (Crohn’s disease and ulcerative colitis), and colorectal cancer can also cause pain
  • Severe pain while experiencing bowel movements could signify a tumour obstructing the rectum or anus

7. Why does my poop smell so bad?

The first thing to remember is that what goes in also comes out, so if you had a spicy meal, chances are you’ll smell it strongly when it exits. Meat produces more smell than vegetables and intestinal bacteria produce several sulphur-containing compounds that are the primary smelly culprits along with fatty acids and skatole, a product resulting from the naturally-occurring process of amino acids being broken down in the intestine. The human nose can detect hydrogen sulphide in concentrations as low as one-half part per billion, making it easy for us to smell stool! Malabsorption, particularly of fats (see FAQ 5), can cause a stronger odour, so talk to your doctor if this persists.

Animals and Poop

  • The white part of bird stool is actually the bird’s version of urine. Birds have only one hole for defecation and “urination”. The white part is uric acid, which is not very soluble in water, as opposed to the urea that mammals excrete, which is why the “urine” from birds is white.
  • Adult African elephants eat 200-250kg of food a day and poop about 50kg daily. Some ingenious individuals in Thailand make paper from elephant dung – an astounding 115 sheets per day from one elephant’s deposits – which is primarily composed of fibre. They claim the paper does not smell and is bacteria-free.
  • Both the Adélie penguin and silver-spotted skipper butterfly – in its caterpillar stage – projectile poop; the caterpillar ejects its stool as far away as 1.4 meters!
  • A rabbit produces two types of digestion bi-products, leading some folks to believe they eat their poop. However, its fecal pellet is brown, hard, and spherical, with little odour, as it is composed mostly of undigested fibre (rabbits don’t generally eat these). However, rabbits also pass cecotropes, composed of nutrients from the rabbit’s digestion, which the rabbit needs to eat a second time to extract the necessary nutrition. These pellets consist of small, soft, shiny globs, each coated with a layer of rubbery mucus, and pass from the body in an elongate mass. As it contains a large mass of beneficial cecal bacteria, it has a strong odour, which the rabbit appears to enjoy. The mucosal coating protects the bacteria as they re-enter the stomach en route to the intestines.

First published in the Inside Tract® newsletter issue 182 – 2012
Image: Rasulov |