Ayurvedic Digestive Types and the Bristol stool chart

by Colette Park
26 May 2022

Ayurveda places great emphasis on good digestion and healthy elimination. Our appetite, ability to digest and the regularity and consistency of our stools provide us with valuable insights into our state of health.

Ayurvedic texts such as the Charaka Samhita, one of the oldest authoritative texts on Ayurveda, written around 400-200 BCE, recognised the link between digestive health and diseased states. Modern science now link imbalances in the gut microbiome to a wide variety of chronic diseases, such as inflammatory bowel disease, asthma, behavioural disorders, diabetes, cardiovascular disease and autoimmune disorders.1

Digestion and Pathogenesis

In Ayurveda, digestive imbalance is viewed as the main cause in almost all diseases (except exogenous causes). Ancient classical texts list the site of origin (Udbhava Sthana) in the pathogenesis (Samprapti) of different diseases, as either the stomach (Amashaya) or large intestine (Pakvashaya). These two Sanskrit words very beautifully describe the function of the digestive organs by their inherent meaning:

  • Amashaya - 'ashaya', the seat or abode of 'ama' or uncooked, unprocessed food material, thus referring to the stomach
  • Pakvashaya – 'ashaya', the seat or abode of 'paakva' cooked, digested food material, thus referring to the large intestine

Ayurveda has two important concepts that gives insight to our digestion and bowel movements: Agni (digestive capacity) and Kostha (expression of bowel habit). The nature of an individual's Agni and Kostha are affected by the dominant Dosha of their constitution or 'Prakriti'. However, it can also be affected by their current Doshic imbalance (acquired due to their diet and lifestyle). You can read more about Prakriti and the Dosha's here.

Agni (digestive capacity)

The word Agni translates as 'digestive fire' or digestion. However, in the context of the 4 types of Agni described in Ayurveda, it refers to digestive capacity:

Vishama Agni (irregular digestion)

  • due to the dry and airy qualities of Vata
  • digestion is erratic and irregular
  • symptoms include an irregular appetite (sometimes hungry, other times not), bloating, flatulence

Tikshna Agni (sharp digestion)

  • due to the hot and penetrating qualities of Pitta
  • digestion is strong or intense and food gets digested very quickly
  • symptoms include thirst, intense hunger, hypoglycaemia, acid reflux

Manda Agni (slow digestion)

  • due to the slow and damp qualities of Kapha
  • digestion is dull, poor or inadequate – even small quantities of food does not digest
  • symptoms include low appetite, lethargy, abdomen feels heavy

Sama Agni (balanced digestion)

  • due to balanced Doshas
  • linked to good appetite, balanced metabolism, digests all meals easily, feeling of vitality and energy.

Kostha (expression of bowel habit)

Koshtha is a concept of how the bowel habits are expressed in each individual and includes the frequency and consistency of stools:

Bowel Type Symptoms
Krura Kostha (hard bowels) • Elimination predominantly affected by Vata (leading to dryness)
• Results in dry, hard stools that are expelled with difficulty or strain
• Elimination does not occur regularly or daily
Mrdu Kostha (soft bowels) • Elimination predominantly affected by Pitta (creating heat and moistness)
• Results in soft, semi-solid or liquid stools that are easy or quick to expel
• Elimination occurs more than once a day
Madhyama Kostha (moderate bowels) • Elimination predominantly affected by Kapha (creating heaviness and moistness)
• Results in well-formed stools (neither too dry, nor too soft) that are moderately easy to expel 2
• Elimination is regular and occurs daily

When the Doshas are balanced, it creates moderate bowels. Thus, Madhyama Kostha (moderate bowels) is the ideal and does not lead to disease.

The Bristol Stool Chart

The Ayurvedic understanding of bowel habit (Kostha) corresponds quite beautifully with the Bristol Stool Chart. The Bristol Stool chart was developed in 1997 as a clinical assessment tool and lists seven types of stools (faeces).

Below is a chart that shows how the Bristol Stool Chart corresponds with the Ayurvedic concept of Kostha and Agni:

Bristol Stool Chart Description Kostha (bowel habit) Agni (digestive capacity)
Type 1 Separate hard lumps, like nuts, difficult to pass Krura (hard) Vishama (irregular)
Type 2 Sausage-shaped, but lumpy Krura (hard) Vishama (irregular)
Type 3 Like a sausage but with cracks on its surface Madhyama (moderate) Manda (slow) / Sama (balanced)
Type 4 Like a sausage or snake, smooth and soft Madhyama (moderate) Manda (slow) / Sama (balanced)
Type 5 Soft blobs with clear cut edges Mrdu (soft) Tikshna (sharp)
Type 6 Fluffy pieces with ragged edges, a mushy stool (diarrhoea) Mrdu (soft) Tikshna (sharp)
Type 7 Watery, no solid pieces, entirely liquid (diarrhoea) Mrdu (soft) Tikshna (sharp)

Digestive imbalances and their link to other diseases

Digestive issues are caused by an imbalance of the Doshas. An individual with a Vata constitution will have a natural tendency towards irregular digestion (Vishama Agni) and constipation (Krura Koshtha). However, such a person may develop sharp digestion (Tikshna Agni) and/or diarrhoea (Mrdu Koshtha) due to stress and eating lots of spicy foods (which has thus created a Pitta imbalance).

These imbalances then have an impact on the rest of the body, creating disease.

Colitis and Rashes

Allopathic Medicine recognise a link between ulcerative colitis (a disease causing inflammation and ulceration of the colon) and inflammatory skin conditions such as rashes, hives and psoriasis.3 Using the Ayurvedic framework it is easy to understand how an excess of Pitta (linked to the fire element, thus an expression of inflammation) in the digestive system can give rise to symptoms of Pitta in the skin.

Parkinson's and Constipation

The presence of constipation in Parkinson's Disease patients is a well-established observation. However, a study in 2001 was the first to show a causal link between long-term constipation and an increased risk of developing Parkinsonism.4 Study participants with long-term constipation (bowel movement less than once day) were 2.7 times more likely to develop Parkinson's Disease later in life. Interestingly, as the frequency of daily elimination increased (2 or more times a day), the likelihood of developing Parkinsonism decreased. Parkinsonism in Ayurveda is named Kampavata – 'Kampa' referring to tremors and 'Vata' indicating the involvement of a Vata imbalance in the disease. It is worth remembering Vata's link to Vishama Agni (irregular digestion) and Krura Koshtha (constipation) in this instance.

Is there a perfect bowel movement?

Unlike the Bristol Stool Chart that states the normal bowel habit produces a stool every 1-3 days, Ayurveda stresses the importance of having a good bowel movement every single day. Even skipping one day or having an incomplete bowel movement, is considered as constipation.

Balanced elimination is a result of Sama Agni (balanced digestion), which results in Madhyama Koshtha (moderate elimination). It has the following qualities:

  • a well-formed, sausage-shaped stool
  • floats in the toilet bowel
  • light brown in colour
  • mild odour
  • not sticky (does not stick to the toilet and the anus remains clean) 5

Ayurvedic wisdom recommends that all food and drink we partake should help support and protect the balance of our digestive functioning. An imbalance in the digestive system is the root cause of Doshic imbalances in the body and by taking steps to balance the digestive system we can improve disease outcomes. To balance digestion, Ayurveda uses nutritional changes based on the qualities and tastes of foods, herbal remedies and self-care practices.

By understanding our digestive type or imbalance, we can make wiser food choices to support and correct our digestive imbalance and support our overall health.

1 Durack, J. & Lynch, S. (2019): “The gut microbiome: Relationships with disease and opportunities for therapy.” The Journal of experimental medicine vol. 216,1: 20-40. doi:10.1084

2 Murthy, K.R.S. (2003): Vagbhata’s Ashtanga Hrdayam, reprint, Volume 1, Sutrasthana 1: Varanasi: Chowkhamba Press.

3 Burgess, L. (medically reviewed by Murrell, D.) (2018): 10 Rashes cause by Ulcerative Colitis, Internet www page at URL: https://www.medicalnewstoday.com/articles/320638

4 Abbott RD, et al. (2001): Frequency of bowel movements and the future risk of Parkinson's disease. Neurology. 2001 Aug 14;57(3):456-62. doi: 10.1212/wnl.57.3.456.

5 Lad, Vasant (2006): Textbook of Ayurveda, Volume 2: A Complete Guide to Clinical Assessment. Albuquerque: The Ayurvedic Press.

Colette Park

BSc (Hons) Ayurveda,
MSc Clinical Nutrition

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