What is in your poo?

We are all familiar with poo, a.k.a. faeces, excrement or stool. We all know it’s a waste product that comes out of our anuses, it’s generally sausage-shaped and brown in colour. Have you ever stopped to think what is in your poo? And why does it even matter?

How much poo?

Encyclopaedia Brittanica tells us that the average poo output per adult person is 100 to 250 grams per day (1). Note this number is the average, don’t be concerned if your output one day is zero (i.e. you’re constipated) or over 1 kg. Also, it is interesting to note that lower-income population groups tend to have heavier stools, mainly due to higher intake of fibre (2).

How often?

On average, faeces are normally expelled from the body once or twice a day (1). Strictly speaking, healthy people seems to defecate 1.2 times per day. This number also vary widely, with values for individual people ranging from 0.21 to 2.54 times per day (i.e. from once every few days to a few times per day). Again, defecation frequency is associated with fibre intake, because it can speed up intestinal transit. It also depends on total food intake and body weight (2).

What is in your poo?

Faeces contain about 75% of water and 25% of solid matter (1, 2). The solid matter includes (1, 2):

Component	Percentage of solid matter (%)
Dead bacteria	~30 (1) and up to 55 (2)
Indigestible food matter such as cellulose	~30
Cholesterol and other fats	10-20
Inorganic substances such as calcium phosphate and iron phosphate	10-20
Protein	2-3
Cell debris and mucus from the intestines	Unknown
Bile pigments such as bilirubin	Unknown
Dead leukocytes (white blood cells)	Unknown

The actual composition depends on food and fluid intake. As mentioned before, one of the main dietary factors is fibre intake. Insoluble fibre holds on to water, while soluble fibre and resistant starch feed bacteria, thus increasing bacterial content (2).

For those who like chemistry, the main elements in poo are oxygen (74%), hydrogen (10%), carbon (5%) and nitrogen (0.7%). The average faecal pH is neutral (i.e. neither acidic nor alkaline), ranging from 5.3 to 7.5 (2).

Physical characteristics

The colour and smell of faeces come from the action of bacteria on bilirubin and food matter, respectively (2).

What can your poo tell you?

The frequency, amount and consistency of stool is frequently used by clinicians to evaluate certain aspects of a person’s health.

The Bristol Scale Stool Form is widely used in healthcare for patients to visually identify their stool type. Out of the 7 types in the scale, numbers 1, 6 and 7 are considered abnormal and 3 and 4 are considered ideal (2).

[Image: Cabot Health, Bristol Stool Chart (CC BY-SA 3.0, https://creativecommons.org/licenses/by-sa/3.0)]

A stool test can reveal even further detail, such as the presence of parasites or blood, undesirable microbial growth and other health conditions.

Diarrhoea

In general, diarrhoea is defined as a minimum of 3 liquid stools per day. It can be acute (up to 3 weeks long, caused by bacterial infection) or chronic (3+ weeks long) (2).

Constipation

Constipation happens in 6-12% of the general population and increases with age (2).

Optimising your poo

If you think your faeces have an abnormal appearance, amount or frequency, you should speak with your doctor and/or dietitian. Depending on their findings, the following things might help:

• Eating more fibre
• Eating less fibre
• Drinking more water
• Removing irritants, such as coffee, alcohol, spicy and fatty foods
• Eating foods that are easy to digest such as broths, soups and stews
• Removing foods you might be allergic or intolerant to
• Performing more physical activity
• Squatting or using a simulating a squatting position while defecating (e.g. using a squatty potty or similar)
• Sitting in half or full lotus (i.e. meditation posture)
• Drinking warm water first thing in the morning
• Drinking coffee
• Probiotics
• Abdominal massage
• Deep breathing and relaxation
• Twisting stretches

References

1. The Editors of Encyclopaedia Britannica. feces: Encyclopædia Britannica, Inc.; 2015 [7 March 2019]. Available from: https://www.britannica.com/science/feces.
2. Rose C, Parker A, Jefferson B, Cartmell E. The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology. Critical reviews in environmental science and technology. 2015;45(17):1827-79.

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