Probiotics are used for a much wider range of conditions than many people realize. In Gut and Physiology Syndrome, Dr. Natasha Campbell-McBride organizes the published research into two groups: digestive disorders first, then conditions beyond the gut.[1]
Digestive Disorders
The book begins its research list with gastrointestinal disorders. The conditions named are[1]:
- Viral infections of the digestive tract
- Necrotising enterocolitis in infants
- Intractable paediatric diarrhoea
- Pseudomembranous colitis
- Traveller’s diarrhoea
- Clostridium difficile enterocolitis
- Helicobacter infection
- Enteropathogenic E. coli infection
- Inflammatory bowel disorders: Crohn’s disease, ulcerative colitis, and chronic pouchitis
- Irritable bowel syndrome
- Lactose intolerance
- Prevention of colonic cancer in laboratory studies
- Infantile colic
For this group, Dr. Natasha states that in many cases adding probiotics to the treatment regimen not only improved the clinical picture but also cured the condition.[2]
Conditions Beyond the Digestive System
Apart from digestive problems, she lists a second group of health problems that have been shown to respond to treatment with probiotics[2]:
- Allergies, including food allergy, asthma, eczema, and atopy
- Autism, schizophrenia, and other psychiatric conditions
- Infections of different kinds
- Hepatitis, liver cirrhosis, and biliary disease
- Meningitis
- Malignancy
- Arthritis
- Diabetes
- Obesity
- Burns of various degree
- Perioperative care and intensive care in surgical patients and patients with massive blood loss
- Autoimmune disorders
- Endocrine and neurological diseases
The Important Context She Adds
Dr. Natasha frames both lists with a specific qualifier, and it’s worth quoting directly rather than summarizing: “These are only the conditions about which scientific papers have been published. However, if you talk to any doctor or practitioner with experience in using probiotics, this list becomes much longer.”[2]
The lists reflect the published literature available when she was writing. Her clinical observation is that experienced doctors and practitioners use probiotics successfully across an even wider range of conditions.
How to Read a List Like This
The breadth of this list shows how far gut flora reaches beyond digestion. Gut bacteria interact with the immune system, nervous system and metabolic function throughout the body. That is a central premise of GAP Syndrome: conditions that look unrelated to digestion can still be connected to what is happening in the gut.
What the Lists Help You Understand
The lists show the range of questions researchers had studied when the book was written. They include digestive conditions, immune disorders and hospital settings. The wording about colonic-cancer prevention explicitly says laboratory studies; perioperative and intensive care refer to treatment settings, not a home supplement routine. Keep those descriptions attached to their entries.[1][2]
A useful next question is what was actually studied: the strain or mixture, the condition, the participants and the outcome. A broad list cannot answer those details by itself. It gives you subjects to investigate, rather than a ranking of products or proof that one probiotic will have the same effect in every listed condition.
How GAPS Uses Fermented Foods and Supplements
Later in the chapter, Campbell-McBride puts homemade fermented foods first. She says some people do well with fermented foods alone, while others find commercial probiotics helpful alongside them. A commercial supplement is therefore not presented as compulsory for every person.[3]
Food permissions and introduction still follow the person’s GAPS stage and response. The research list does not give permission to introduce a food early, replace prescribed treatment or choose a dose for an infant. The practical starting point is the current protocol, not the length of a condition list.
Our family has followed GAPS since July 2024. As a working, homeschooling mother of six, I want the explanation to lead to something useful at home. Understanding the terms helps me read the books carefully and keep food decisions connected to the protocol. You can read our family’s GAPS story for the experiences behind this blog.
Keep Reading
The food and immune-support guide explains fermented foods within the immune-food discussion. Use the Stage 1 guide or the Full GAPS guide for the actual food context you are following.
For the kitchen side of this topic, look for the Crock & Jar: Ferments for GAPS Families course in my course catalog. It is the companion to consider if you want to spend more time on fermented foods.
References
- Campbell-McBride, N. Gut and Physiology Syndrome (2020), probiotic chapter, digestive-condition research list, printed page 307.
- Campbell-McBride, N. Gut and Physiology Syndrome (2020), probiotic chapter, other-condition list and published-literature qualifier, printed page 308.
- Campbell-McBride, N. Gut and Physiology Syndrome (2020), conclusion to the probiotic chapter: fermented foods first; food-only and combined approaches.
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