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Bloating and stools

Posted 6 years ago by Brendan

In response to some of the feedback from our last post about the Food Hospital Fibre Challenge and using the Bristol Stool Form Scale to rate the consistency of stools, this post is a guide to what else bloating sufferers can learn about their digestive systems by taking notice of how their stools change from day to day.

Digestive function 

Gastrointestinal function is really just a process of ingestion, digestion, assimilation and elimination. Putting it simply, the food and drink we eat is broken down so the usable constituents can be absorbed and used by the body, while the unusable material is moved along to be eliminated with other waste products. For more on the digestive process read the digestive health page.

While stools aren’t exactly a polite topic of conversation, their obvious features are good indications of gastrointestinal function. So if you regularly experience abdominal bloating, indigestion, wind or other digestive complaints, there's a good chance your stools could have a few clues about the state of your digestive health. 

Normal stools 

Everybody is different but generally speaking a ‘normal’ or healthy stool (type 4 - 5 on the Bristol Stool Form Scale) is well formed with a relatively soft and uniform texture, light to medium brown colour and cylindrical in shape. They should be easy to pass without straining, fall slowly upon reaching the water and have no foul or significant odour. These features are characteristics of good gastrointestinal function.

The Bristol Stool Form Scale. A printable version available on The Fibre Challenge website -

Undigested food  

Perhaps the most important feature bloating sufferers should keep an eye out for is the presence of undigested food. Failing to effectively break down the food we eat into smaller, more absorbable components, prevents their absorption from the intestines, allowing poorly digested material to pass into the bowel. The result of bacterial fermentation digesting these unabsorbed food fragments is abdominal bloating, distension, and wind. The articles What causes bloating? and Bloating and flatulence discuss this process in more detail.  

Many people occasionally notice fragments of high fibre foods such as corn in their stools, which is nothing to worry about. For more on digestion and dietary fibre you can read the article, Does fibre cause bloating? However, the ongoing presence of undigested food in the stool can be a sign you aren’t chewing your food properly, aren’t producing adequate digestive enzymes, or that your bowel transit time is too fast. It may be worth taking your time when eating, using aperitifs or bitters to stimulate digestion before meals or talking with a health professional about supplementing with digestive enzymes. Daniel's piece, Stomach acid and bloating, talks more about the importance of stomach acid. 

Stool colour

A stool's typical brown colour is due to the presence of bilirubin - a metabolite of the liver-processing hemoglobin left over from old red blood cells. This bilirubin is released into the bile (a yellow-greenish fluid that helps digest fats in the intestine and soften the stools) and eliminated via the bowels. The longer they spend in the gastrointestinal tract the more these bile pigments are altered, turning green to brown, so depending on the concentration of bile and the transit time, stool colour can range from pale yellow or greenish to very dark brown. The type of foods eaten recently and some medications can affect stool colour, as anyone who regularly eats beetroot will no doubt be aware of.


Possible cause 

Pale, grey or clay-coloured 

A lack of bile in the stool - poor production, secretion or obstruction. May be due to cholecystitis, gallstones or hepatitis.
An increased transit time - due to infections such as giardia.
Certain medications such as aluminum containing antacids.

Yellow or greenish coloured 

A lack of bile in the stool (liver or gallbladder dysfunction or congestion) or decreased conversion of bile pigments due to an increased transit time.
Acute infections producing diarrhea.

Dark coloured

Slow transit time - waste material has remained and darkened  in the colon for too long. For more on decreased transit time read 'Constipation and bloating'. 
Certain medications such as anti-diarrheals, iron supplements or activated charcoal.

Black, sticky or tarry 

Bleeding in the upper gastrointestinal tract - blood has turned black and sticky by the time it is eliminated. This may be due to ulcers, gastritis, alcoholism or injury. Best have it investigated.
Certain medications such as anti-diarrheals, iron supplements or activated charcoal. 

Red or maroon 

Bleeding in the lower gastrointestinal tract colon. May be due to hemorrhoids, diverticulitis, IBD, fissures, colorectal caner or other lower bowel conditions. If you notice any blood in your stools its best to have it investigated promptly.
Eating bright red pigmented foods such as beetroot. 


Suggests a total lack of bile due to a liver or pancreas problem. Best see your doctor soon as possible.  

Floats or sinks

A heavy stool that sinks rapidly suggests the stool is extra hard, dry and compact after spending too long in the colon. This type of stool is likely to improve with more dietary fibre and by drinking more water. For more on dietary fibre read Does fibre cause bloating?. If you regularly experience hard, heavy stools, get involved in the Food Hospital Fibre Challenge.

A particularly soft or greasy stool that floats easily, is difficult to flush away or sticks to the bowel, suggests an increased fat concentration. Often these stools are also smelly. The digestive enzyme lipase and bile salts are required to break down and absorb fats and so conditions affecting their production or secretion from the pancreas and liver respectively may account for consistently producing these stools. Any condition that affects the absorptive lining, interrupting fat absorption (such as IBD, Coeliac disease, etc) may also be responsible. Rarely noticing this type of stool is much more likely to be associated with eating a particularly large or fatty meal. Avoiding saturated fats and taking digestive enzymes or lecithin granules may help improve fat emulsification and absorption.

Mucus and pus

The presence of clear or whitish, jelly-like mucus in stools suggests inflammation in the mucus membranes lining the gastrointestinal tract. Some mucus is normal as it helps to moisten, lubricate and protect the delicate lining of the gastrointestinal tract. Those with conditions such as IBS (previously known as 'mucous colitis'), IBD or food allergies/intolerances, where there is some degree of gastrointestinal irritation, will often experience excessive amounts of mucus passing with stools. Soothing demulcents and mucilages such as slippery elm bark, aloe vera juice, marshmallow or liquorice root as well as gastrointestinal anti-inflammatories such as turmeric, ginger, chamomile or meadowsweet can all help alleviate the inflammation responsible. 

Mucus shouldn't be confused with pus in the stool which is more sticky, creamy and yellowish in colour. Pus indicates the presence of an active infection possibly due to an abscess, parasite, diverticulitis or tumor. Get this seen to by a doctor promptly.

Narrow, ribbon or pencil thin stools

If experienced consistently, very thin stools suggest some degree of structural narrowing, stricture or obstruction in the colon or tension in the bowel’s neuromusculature function. If you notice these type of stool for more than a week or so, see your doctor.

Consider it

Nobody is asking you to talk about your stools with friends or strangers, but taking notice of them and how they might change from day to day depending on what you’ve eaten or been doing, is an easy way for you to get an insight into how your insides are working. Most day to day changes are of little real concern, however don’t let embarrassment stop you discussing any changes with your doctor or health professional.

Any questions or comments? Lets us know about them here.

About Brendan O'Loughlin

Brendan is a integrative naturopath, nutritionist and yoga teacher. He has completed training in Naturopathy, Nutrition, Herbal Medicine, Yoga, Iridology and Live Blood Analysis.

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