Beyond "Eat More Fibre"

Chronic constipation — defined as fewer than three bowel movements per week, or consistent difficulty passing stool — affects approximately 20% of the adult population. It is more than an inconvenience: chronic constipation increases toxin reabsorption, disrupts the microbiome, impairs oestrogen metabolism, and significantly reduces quality of life.

The standard medical advice — "eat more fibre and drink more water" — helps some people but fails many others. That is because constipation has multiple possible root causes, and the solution depends entirely on which cause (or combination of causes) applies to you.

Understanding Normal Motility

Healthy colonic transit involves a coordinated sequence: the migrating motor complex (MMC) sweeps through the small intestine during fasting, moving contents into the colon. In the colon, mass movements (strong propulsive contractions) occur several times daily — typically triggered by eating (the gastrocolic reflex) — pushing stool toward the rectum. When stool reaches the rectum, stretch receptors trigger the urge to defecate.

Constipation can result from disruption at any point in this process: impaired motility, insufficient bulk, pelvic floor dysfunction, or neurological signalling problems.

Root Cause 1: Methane-Dominant SIBO (IMO)

Intestinal methanogen overgrowth (IMO) is one of the most underdiagnosed causes of chronic constipation. Archaea (particularly Methanobrevibacter smithii) produce methane gas, which directly slows intestinal transit by affecting smooth muscle contractions. A study in The American Journal of Gastroenterology found that methane levels on breath testing correlated directly with the severity of constipation — higher methane, slower transit.

If your constipation is accompanied by bloating, brain fog, and does not respond to fibre, IMO should be investigated through a lactulose breath test.

Root Cause 2: Hypothyroidism

Thyroid hormones regulate metabolic rate throughout the body, including gut motility. Even subclinical hypothyroidism (elevated TSH with normal T4) can significantly slow colonic transit. If your constipation is accompanied by fatigue, weight gain, dry skin, hair loss, and cold intolerance, thyroid function should be evaluated. A full thyroid panel (TSH, free T4, free T3, thyroid antibodies) provides more information than TSH alone.

Root Cause 3: Dysbiosis

The gut microbiome directly influences motility through production of short-chain fatty acids, serotonin, and other neuroactive compounds. Individuals with chronic constipation consistently show reduced microbial diversity and lower levels of butyrate-producing bacteria compared to healthy controls. Butyrate stimulates colonic motility and nourishes the cells lining the colon.

Research insight: A 2022 study found that transferring gut microbiota from patients with slow-transit constipation into germ-free mice induced constipation in the recipients — demonstrating that the microbiome alone can cause motility dysfunction.

Root Cause 4: Pelvic Floor Dysfunction

In some people, the muscles of the pelvic floor do not coordinate properly during defecation. Instead of relaxing to allow stool to pass, they contract — a condition called dyssynergic defecation or pelvic floor dyssynergia. This affects up to 50% of people with chronic constipation and is particularly common after childbirth, pelvic surgery, or periods of chronic straining.

The hallmark symptom is a sensation of incomplete evacuation or the need for manual assistance. Diagnosis requires anorectal manometry or a balloon expulsion test. Treatment involves biofeedback therapy, which has a success rate of 70 to 80% and is more effective than laxatives for this subtype.

Root Cause 5: Medication Side Effects

Numerous medications cause constipation as a side effect, including opioids, anticholinergics, calcium channel blockers, iron supplements, antacids containing aluminium or calcium, and antidepressants (particularly tricyclics). If your constipation began or worsened after starting a new medication, discuss alternatives with your prescriber.

Root Cause 6: Insufficient Magnesium

Magnesium relaxes smooth muscle throughout the body, including in the colon. It also draws water into the intestinal lumen through osmotic effects, softening stool. Magnesium deficiency is extremely common — estimated to affect 50% or more of the Western population — due to depleted soils, processed food diets, and chronic stress (which depletes magnesium).

Evidence-Based Solutions

Dietary Approaches

  • Soluble fibre (not just any fibre): psyllium husk is the best-studied fibre for constipation, with consistent positive results in clinical trials. Start with 5g daily and increase gradually. Insoluble fibre (wheat bran) can actually worsen constipation in some people
  • Kiwifruit: two green kiwifruits daily have been shown to improve bowel frequency and stool consistency in multiple trials, likely due to their actinidin enzyme and unique fibre profile
  • Prunes: contain sorbitol, fibre, and polyphenols that stimulate motility. 50g daily (about 5 prunes) is an effective, well-studied dose
  • Adequate hydration: while water alone does not cure constipation, inadequate hydration worsens it. Aim for 2 litres daily, more in hot weather or with exercise

Supplementation

  • Magnesium citrate or oxide (300-500mg at bedtime): osmotic laxative effect plus smooth muscle relaxation. Start low and titrate up
  • Probiotics: Bifidobacterium lactis BB-12 and Lactobacillus rhamnosus GG have the most evidence for improving transit time
  • Vitamin C (1-3g daily): has a mild osmotic laxative effect at higher doses

Lifestyle

  • Movement: regular physical activity stimulates the gastrocolic reflex and improves colonic transit. Even a 15-minute walk after meals can be effective
  • Toilet positioning: using a footstool to elevate your feet creates a squat-like position that straightens the anorectal angle, facilitating easier elimination
  • Honouring the urge: repeatedly ignoring the urge to defecate weakens the rectal reflex over time. When nature calls, respond promptly

Finding Your Solution

The key to resolving chronic constipation is identifying which root cause applies to you. GutIQ evaluates your bowel habits, dietary patterns, medication history, stress levels, and associated symptoms to identify the most likely contributing factors and recommend the most targeted interventions.