By Phillip Day
See also: Blood Sugar Imbalance • Cancer • Diabetes • Fatty Liver Disease (MASLD/NAFLD) • Heart Disease • Kidney Disorders • Obesity & Weight Gain • Stress • Thyroid Disorders
At a Glance
Digestive disorders affect hundreds of millions of people worldwide, and range from occasional indigestion to chronic inflammatory bowel disease. They include acid reflux, irritable bowel syndrome (IBS), constipation, coeliac disease, Crohn’s disease, ulcerative colitis, diverticular disease, peptic ulcers and disturbances of the gut microbiome.
The digestive tract is far more than a food-processing tube. It is one of the body’s largest immune organs, home to trillions of bacteria and other microorganisms, and responsible for extracting the nutrients from which every cell in the body is built. When digestion is impaired, health problems often extend well beyond the gut.
Key Message
Many digestive disorders have different immediate causes, but they frequently share common underlying drivers: poor diet, ultra-processed foods, disruption of the gut microbiome, chronic stress, lack of fibre, inactivity, certain medications and nutritional deficiencies. While some conditions require specialist medical treatment, many digestive complaints improve substantially when the digestive system is given the conditions it needs to heal.
What Is It?
Digestion begins in the mouth and continues through the stomach, small intestine and colon. Food must be broken down mechanically and chemically before nutrients can be absorbed into the bloodstream.
Along the way, stomach acid, digestive enzymes, bile, beneficial bacteria and the intestinal lining all play essential roles. If any part of this finely balanced system begins to malfunction, symptoms may appear throughout the digestive tract.
Common digestive disorders include:
Acid reflux (GORD)
Peptic ulcers
Helicobacter pylori infection
Irritable bowel syndrome (IBS)
Inflammatory bowel disease (Crohn’s disease and ulcerative colitis)
Coeliac disease
Diverticular disease
Constipation
Small intestinal bacterial overgrowth (SIBO)
Food intolerances
Each has its own characteristics, but they frequently overlap and may exist together.
Symptoms
Abdominal pain or cramping
Bloating
Excess wind
Heartburn or acid reflux
Constipation
Diarrhoea
Alternating constipation and diarrhoea
Blood or mucus in the stool
Nausea
Difficulty swallowing
Unexplained weight loss
Poor nutrient absorption
Persistent fatigue
Symptoms such as severe abdominal pain, persistent vomiting, difficulty swallowing, unexplained weight loss or blood in the stool should always be medically assessed.
Possible Causes and Contributing Factors
Diet is often the starting point. Modern diets are frequently dominated by refined carbohydrates, sugar, ultra-processed foods, emulsifiers, artificial additives and unhealthy fats while being deficient in fibre, minerals and naturally fermented foods.
The gut microbiome has emerged as one of the most important areas of digestive research. Trillions of bacteria live within the intestine, helping digest food, manufacture vitamins, regulate immunity and maintain the intestinal barrier. Antibiotics, repeated infections, poor diet and chronic stress may all disturb this balance.
Food intolerance also deserves consideration. Coeliac disease is an autoimmune reaction to gluten that damages the lining of the small intestine. Others without coeliac disease may still experience symptoms after eating wheat or other foods, although the exact mechanisms are still being investigated.
Inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis involve chronic immune-mediated inflammation. Their precise causes remain uncertain, with genetics, immune function, environmental exposures and alterations in the microbiome all thought to contribute.
Constipation frequently results from inadequate fibre, poor hydration, inactivity and diets dominated by processed foods.
Reflux is commonly associated with excess abdominal weight, hiatal hernia, smoking, large evening meals and certain foods and drinks. Although excess stomach acid is often blamed, insufficient stomach acid may also contribute in some people by impairing digestion and delaying stomach emptying.
Stress has a profound influence on digestion. The gut and brain communicate continuously through the gut-brain axis. Anxiety, emotional distress and chronic stress can alter bowel movements, stomach acid production, gut sensitivity and microbial balance.
Conventional Medical Care
Treatment depends upon the diagnosis
Acid reflux may be treated with antacids, H2 blockers or proton-pump inhibitors
Helicobacter pylori infection usually requires combination antibiotic therapy
Crohn’s disease and ulcerative colitis often require anti-inflammatory medicines, immune-modifying drugs or biological therapies, with surgery reserved for selected cases
Coeliac disease requires lifelong avoidance of gluten
IBS treatment may include dietary modification, stress management and medications directed at specific symptoms
Diverticulitis sometimes requires antibiotics or surgery if complications develop
Early diagnosis is important because persistent digestive symptoms can occasionally signal serious disease, including bowel or stomach cancer
TAKE ACTION
Diet
Follow The Food For Thought Lifestyle Regimen
Base meals around vegetables, salads, legumes if tolerated, quality protein, nuts, seeds and beneficial fats.
Reduce or eliminate ultra-processed foods
Avoid excessive sugar and refined carbohydrates
If coeliac disease has been diagnosed, avoid gluten completely
Individuals with persistent gut symptoms should consider whether modern wheat products are contributing to their condition
Those with persistent digestive symptoms may benefit from a supervised elimination diet to identify individual food triggers
Fermented foods such as natural yoghurt, kefir and sauerkraut may help support a healthier gut microbiome where tolerated
Eat slowly and chew thoroughly
Avoid consistently overeating
Finish the last meal several hours before bedtime
Hydration
Drink adequate clean water throughout the day
Increase fluid intake if constipation is a problem
Avoid relying on sugary drinks
Moderate alcohol intake
Excess caffeine may aggravate reflux and bowel symptoms in susceptible individuals
Lifestyle
Exercise regularly
Maintain a healthy body weight
Reduce abdominal obesity where present
Manage chronic stress through relaxation, exercise, adequate sleep and time outdoors
Do not smoke
Allow adequate time for meals rather than eating under pressure
Avoid lying down immediately after eating
Aim for regular bowel habits rather than repeatedly ignoring the urge to empty the bowel
Nutritional Support
The Core Supplement Programme
Vitamin D3 optimisation
Magnesium
Vitamin C
A broad-spectrum probiotic may be helpful after antibiotic treatment or where gut flora has been disrupted
Digestive enzymes may benefit selected individuals with impaired digestion
Soluble fibre may improve bowel regularity where appropriate
Omega-3 fatty acids may help support healthy inflammatory balance
For dosage ranges, preferred forms, practical guidance and supporting evidence, visit The Special Briefing Room at the back of this book.
Medical Review
Seek medical assessment for persistent digestive symptoms lasting more than a few weeks.
Blood in the stool should never be ignored
Unexplained weight loss always requires investigation
Long-term reflux should be assessed because persistent inflammation may damage the oesophagus
Those with ongoing diarrhoea, anaemia or suspected malabsorption may require blood tests, stool testing, endoscopy or colonoscopy
Do not discontinue prescribed medication without discussing it with your healthcare professional
Common Mistakes
Treating symptoms while ignoring diet
Assuming every digestive complaint is caused by excess stomach acid
Eating too quickly
Relying heavily on processed foods
Taking repeated courses of unnecessary antibiotics
Ignoring constipation
Self-diagnosing food intolerance without proper assessment
Assuming bloating is simply ‘normal’
Worth Knowing…
Your digestive tract houses trillions of microorganisms that collectively weigh around one to two kilograms. Many scientists now regard this microbial ecosystem as an additional organ because of its importance to immunity, metabolism and overall health.
Much of the body’s immune activity is closely associated with the intestine. Looking after digestive health is therefore about far more than avoiding indigestion.
Many people notice substantial improvements in bloating, reflux, bowel regularity and energy simply by replacing processed foods with whole foods, increasing physical activity, sleeping better and restoring a healthier gut microbiome. While these measures are not cures for every digestive disease, they provide the foundation upon which good digestive health is built.
Key Takeaway
The digestive tract lies at the heart of human health. It not only digests food but nourishes the immune system, supports the microbiome and supplies every cell in the body with its raw materials. Modern lifestyles place enormous strain upon this remarkable system. Fortunately, it is also one of the body’s most resilient organs. Remove the irritants, restore good nutrition, support a healthy microbial balance and give the gut time to recover, and many digestive complaints improve far more than most people imagine possible.
(see Scientific References)
Excerpted from the new ABC’s of Disease (2026) by Phillip Day
770 pages of what you can do.