Functional dyspepsia supplement protocol — what the trial evidence supports
Functional dyspepsia (FD) is upper-GI symptoms — postprandial fullness, early satiety, epigastric pain or burning — without a structural explanation on endoscopy. The Rome IV criteria divide FD into postprandial distress syndrome (PDS, fullness-and-satiety phenotype) and epigastric pain syndrome (EPS, pain-and-burning phenotype). Standard medical therapy includes PPIs (best for EPS), prokinetics where available (limited in many regions), H. pylori testing and treatment, and neuromodulators (tricyclic antidepressants in low dose). The supplement layer is one of the better-evidenced in functional gut disorders — STW 5 (Iberogast), enteric peppermint + caraway, and ginger all carry meaningful trial weight.
What actually has trial evidence
STW 5 (Iberogast) — 9-herb fixed combination
20 drops three times daily before meals, for at least 4 weeks
STW 5 is a German fixed combination of nine plant extracts (bitter candytuft, peppermint, chamomile, caraway, liquorice, lemon balm, celandine, angelica, milk thistle). Multiple double-blind RCTs in functional dyspepsia and overlapping IBS endpoints have shown symptomatic improvement comparable to prokinetic drug therapy in FD. Mechanism is multimodal: smooth-muscle modulation (relaxation of fundus, contraction of antrum), modest acid modulation, mucosal protection. Mild GI upset is the most common adverse effect. Avoid in liver disease (rare hepatotoxicity reports led to a 2018 reformulation in some markets removing celandine).
Peppermint oil + caraway oil (enteric-coated)
90 mg peppermint oil + 50 mg caraway oil, enteric-coated, t.i.d. before meals
The Madisch RCT and subsequent meta-analyses support enteric peppermint + caraway for FD, particularly for the postprandial distress phenotype. Mechanism: peppermint relaxes gastric smooth muscle and reduces fundic tone; caraway has carminative action. Enteric coating is non-negotiable — uncoated peppermint reflux into the oesophagus produces heartburn and may worsen symptoms.
Ginger (Zingiber officinale)
1 g/day in divided doses with meals (500 mg b.i.d. or 250 mg q.i.d.)
Ginger has prokinetic activity (improves gastric emptying), 5-HT3 receptor antagonism (anti-nausea), and modest carminative effect. The Wu RCT and others support ginger in FD with delayed gastric emptying phenotypes. Pairs well with peppermint+caraway when the dominant complaints are fullness, early satiety, and post-meal nausea.
Curcumin (bioavailable formulation)
500 mg b.i.d. of a bioavailable curcumin (phytosome, BCM-95, or similar)
Older comparative trial vs domperidone showed comparable improvement at 7 days. Small, limited follow-up. May have value in EPS phenotype where pain and burning predominate, particularly given anti-inflammatory and mucosal-protective mechanism plausibility.
Digestive enzymes (with meals — only for selected patients)
Broad-spectrum pancreatic enzyme blend (amylase, protease, lipase) with main meals
Useful primarily in suspected mild pancreatic insufficiency or in users with documented fat malabsorption (steatorrhea, weight loss); not as broadly useful in typical FD. Worth a 4-week trial if pancreatic insufficiency is on the differential and stool elastase is low-normal.
The lifestyle and dietary base — often the biggest lever
Several modifiable inputs often produce larger improvements than any supplement:
- Eat slowly, smaller portions, more frequently — particularly important in PDS phenotype where gastric accommodation is impaired.
- Reduce high-fat meals — fat delays gastric emptying and is a common trigger in PDS.
- Reduce alcohol and coffee — coffee particularly aggravates EPS phenotype.
- Address food triggers individually — common triggers include wheat, onion, large amounts of dairy, carbonated drinks.
- Stress management and gut-directed cognitive behavioural therapy — gut-brain axis is a major driver of FD; trial evidence supports CBT.
- Smoking cessation — strongly associated with FD persistence; cessation often improves symptoms.
- Sleep regularity — disrupted sleep reliably worsens FD symptoms.
- Test and treat H. pylori — if not already done, this is the single highest-yield intervention in any FD work-up.
What to skip
- Long-term high-dose PPI use without re-evaluation — appropriate for short-term EPS, but PPIs have downstream issues (B12 absorption, magnesium loss, bone density signal) when used indefinitely without indication.
- Generic "digestive bitters" without trial-grade standardisation — limited specific evidence; STW 5 is the bitter combo with the trial evidence.
- Activated charcoal — popular as a "bloat" remedy; will reduce absorption of medications taken simultaneously; minimal evidence in FD.
- HCl betaine "low stomach acid" supplements — used by some for FD on the assumption of hypochlorhydria; quality evidence is essentially absent, and PPIs would be contraindicated if true hypochlorhydria were the diagnosis.
- Apple cider vinegar regimens — anecdotal; no quality evidence; can erode dental enamel.
- Generic probiotics for FD — limited specific evidence; strains matter, and the FD literature is much thinner than the IBS literature.
What to track
Use a validated tool: the Nepean Dyspepsia Index (NDI) or the Leeds Dyspepsia Questionnaire (LDQ). Track weekly for symptom score and intensity. A clinically meaningful response is typically a 50% reduction in symptom score at 4–8 weeks. Reassess any supplement at 4–8 weeks of consistent use. If the supplement is producing no measurable benefit by 8 weeks at full dose, it is not the rate-limiting input.