Nutritional therapy practitioner and ION Lecturer Catherine Jeans explores four of the most common gastrointestinal complaints.

This article was originally published in print in the Winter 2022-23 issue of Optimum Nutrition magazine.

Our digestive system – aka our gut – plays a major role in optimum health and wellbeing. It impacts so many other bodily systems, starting with the absorption of nutrients that every cell in the body needs to stay healthy.

It has the incredible ability to extract vitamins, minerals, energy, fibre and building blocks of life from food — something humans on the outside world can only do in a laboratory.

The gut is also home to the majority of the immune system; it creates brain messengers such as serotonin and dopamine; it helps to remove toxins and other potentially harmful substances via our bowel movements; and it acts as a barrier to the outside world — working hard to let the good stuff in (i.e. nutrients) and to keep the bad stuff out (e.g. toxins and pathogenic bacteria).

Speaking to a GP

A doctor should be the first point of call with any new digestive issues, to rule out serious illness or the need for medical attention.

This is particularly important if there are any changes in bowel movement (that are not usual), or new onset of bloating or abdominal pain.

It is also important to speak to a GP if there is any blood in your stools, or if your stools are dark or black, which can indicate gastrointestinal bleeding.

Not everyone feels comfortable speaking about their toilet habits; however, medical and health practitioners are very used to discussing the ins and outs of the human digestive system — so if something is concerning you, don’t be embarrassed.


Constipation is thought to affect 1 in 7 adults in the UK and 1 in 3 children at some point in their lives.

Symptoms: Not passing a regular stool (e.g. 1 to 3 times per day), feeling unable to properly empty your bowels, or having to strain. You may also experience bloating and discomfort.

See a GP: If constipation doesn’t resolve after 14 days, or there is blood in stools, or stools are dark or black.

Discuss with GP: Review any prescriptions as some medications might cause constipation. Constipation can also be a symptom of an underactive thyroid. Rule out coeliac disease, especially if it is in the family.

Nutritional therapy support: Dietary factors may include low fibre, low fluid intake, and too much sugar, processed foods or wheat. There may also be potential microbiome imbalances, maldigestion, or thyroid issues. A nutritional therapist may assess the need for magnesium or vitamin C (not for deficiency) as these may help to support bowel movements. Lifestyle factors to address include stress, lack of exercise, and vagus nerve exercises.


This is characterised by loose, frequent bowel movements, often with an urgency to go to the toilet. Severity varies, from watery to mushy stools.

See a GP: If you have ongoing diarrhoea (with or without vomiting) that doesn’t resolve after a few days, if you have blood in the stool or dark or black stools, or if you’re also experiencing unintentional weight loss.

Discuss with GP: A possible bacterial infection (e.g. food poisoning with E. coli), or viral or parasitic infection (e.g. from contaminated water — perhaps from travel abroad). Your GP may offer a stool test to check for infection and to rule out inflammation and/or blood in the stools. If your diarrhoea is ongoing, you may be referred to a gastroenterologist. Discuss if you are on any prescription medications which may contribute to diarrhoea; and rule out coeliac disease.

Nutritional therapy support: Diarrhoea is common in irritable bowel syndrome (IBS), food allergies/intolerances, anxiety, depression, and stress.

A nutritional therapy practitioner can help with a bespoke dietary plan; this may include a low-FODMAP diet (restricting consumption of all fermentable carbohydrates, usually for a short time period) or a food elimination programme, and key foods and nutrients to support gastrointestinal barrier function.

They may also want to explore microbiome imbalances, small intestinal bacterial overgrowth (SIBO), food intolerances, wheat allergy and stress management techniques. They may suggest supporting your diet with supplements to maintain nutrients lost with ongoing diarrhoea — e.g. zinc, B vitamins, iron.

Acid reflux and heartburn

This is characterised by a burning feeling in the chest, sour taste, burping, bad breath, hoarse voice, cough/hiccups, nausea, difficulty swallowing and bloating. You may be diagnosed with GORD (gastro-oesophageal reflux disease).

See a GP: If you are experiencing ongoing symptoms more than three times per week, if antacid medication is not working, if you are having difficulty swallowing, if your symptoms are severe, or if you are experiencing persistent vomiting or blood in your vomit.

Discuss with GP: Rule out infection from Helicobacter pylori, a bacteria associated with GORD. If you’re already on medication, discuss regular nutrient screening as stomach acid-lowering medication can deplete nutrients, e.g. B12, folate, iron.

Review other prescriptions that may contribute to GORD, for example some blood pressure drugs. Your GP may refer you to a gastroenterologist to check the health of your oesophagus and stomach lining.

Nutritional therapy support: Common triggers include coffee, alcohol, chocolate, spicy food, tomatoes, fried foods, and smoking. In some cases, people are triggered by wheat/gluten, dairy, processed foods and high-sugar foods.

A nutritional therapist may advise eating smaller, more frequent meals and not eating close to bedtime. Overweight is also a common trigger, so a nutritional therapy practitioner can support weight management. Other areas to look at include stress and anxiety support, microbiome balance, vagal tone and optimising digestion.

Bloating and wind

This may entail swelling in the tummy, a distended tummy, discomfort, excess wind and farting, and a rumbling tummy. It may occur after eating, or at any time of day.

See a GP: If you’re bloating for more than three weeks or bloating regularly, several times per week; or if there are any lumps or swelling in the tummy, or it is difficult to move when bloated.

Discuss with GP: Your GP will want to establish the location of the swelling (inside or outside the gut), which may involve a physical exam of the abdomen.

They may offer a blood test to rule out serious issues, such as ovarian cancer or coeliac disease, and they may consider anti-spasmodic medication to reduce your discomfort.

Nutritional therapy support: Common triggers include constipation, stress, microbiome imbalance in the large or small intestine (SIBO), maldigestion, food intolerances, and poor vagal tone.

A nutritional therapy practitioner may recommend a low glycaemic load or low FODMAP diet. Lifestyle factors to address include regular exercise and stress support.

External signs of digestive issues

There are also many conditions outside the gut that can be linked to digestive health. You may benefit from addressing gut symptoms if you also experience:

  • Skin problems, e.g. eczema, psoriasis, acne
  • Hormonal issues, e.g. endometriosis and premenstrual syndrome
  • Fatigue
  • Difficulty losing weight
  • Pre-diabetes
  • Mental health issues, e.g. anxiety or depression
  • Poor cognitive function
  • High cholesterol

Tests a GP or gastroenterologist may offer

There is a multitude of tests that GPs and specialists can use to help rule out anything serious or to provide a diagnosis. A physical examination of the abdomen may be undertaken in the first instance.

Depending on symptoms, a stool test can be useful to check for infection or inflammation and possibly a blood test for inflammatory markers, nutrient levels and markers of coeliac disease. (It’s important to notify the GP if you’re already on a gluten-free diet as it can affect the results of a coeliac test.)

If the GP makes a referral to a gastroenterologist, further investigations may be recommended, e.g. an endoscopy (a non-surgical procedure to examine the upper gastrointestinal tract) or a colonoscopy (to examine the lower digestive tract and potentially take a biopsy).

Patients who are experiencing high stress levels may be referred to a talking therapy such as CBT (cognitive behavioural therapy).

Functional gut tests with a nutritional therapy practitioner

A fully registered nutritional therapy practitioner may offer functional tests to help assess underlying imbalances that may contribute to symptoms.

Rather than looking for markers of pathology (illness) — which will be covered by a medical doctor — a nutritional therapy practitioner may want to assess imbalances in gut function and the health of the gut microbiome.

One of the most common tests used by practitioners is a functional microbiome assessment, which may include markers of stool chemistry to assess digestion and the health of the gastrointestinal lining.

This stool test allows the practitioner to look for evidence-based patterns of microbial imbalance that may correlate with symptoms; for example, an overgrowth of some methane-producing bacteria has been associated with constipation.

This information enables the practitioner to provide a tailored programme of dietary, nutritional and supplement support that is tailored to the individual’s microbiome status and nutritional needs.

Small intestine bacterial overgrowth

A nutritional therapy practitioner may also consider a small intestine bacterial overgrowth (SIBO) test to assess bacterial imbalances in the small intestine. This is an at-home test, conducted via breath samples.

Sometimes a food intolerance test may be recommended to assess whether certain foods, compounds and additives may be contributing to symptoms.

This is a blood analysis that tests for specific markers, typically immunoglobulin G (IgG) antibodies and inflammatory proteins.

A nutritional therapy practitioner will be able to explain the results and offer advice on how to safely, and temporarily, eliminate any foods that may be contributing to symptoms and how to carefully reintroduce them into the diet.

A practitioner may also want to assess nutrient status, to identify any deficiencies caused by ongoing gut symptoms and ensure optimal levels of nutrients required to support gut health. This may include vitamin D, zinc and essential fatty acid levels.

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