Functional Dyspepsia: The Evidence-Based Supplement Protocol

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Functional dyspepsia (FD) — chronic upper-abdominal fullness, early satiety, and burning with no ulcer or structural cause — is driven by impaired gastric accommodation, delayed emptying, and visceral hypersensitivity. The 2017 ACG/CAG dyspepsia guideline sets the first-line path: test for Helicobacter pylori and treat if positive, then a trial of a proton-pump inhibitor, then a low-dose tricyclic neuromodulator or a prokinetic if those fail. Supplements are adjuncts to that backbone, and only a handful have genuine randomized-trial support: a fixed peppermint–caraway oil combination, the multi-herb formula STW 5 (Iberogast), and ginger for the delayed-emptying phenotype. Overall the evidence here is modest, and much of it comes from manufacturer-linked trials—worth knowing before you spend. Here is what the trials actually show, graded honestly, and what to skip.

Peppermint + Caraway Oil, ~90 mg + 50 mg Twice Daily — Moderate Evidence

The best-evidenced supplement for FD is the fixed combination of enteric-coated peppermint oil and caraway oil (marketed as Menthacarin or Enteroplant). A systematic review and meta-analysis of placebo-controlled trials (three FD studies, 249 patients, eligible for pooling) found it significantly reduced epigastric pain intensity (standardized mean difference 0.80; 95% CI 0.39–1.21) and more than doubled the odds of meaningful global improvement, with effects comparable to a reference drug. The original 28-day double-blind RCT in 96 outpatients found pain fell 40% on the combination versus 22% on placebo, and 67% versus 21% were "much or very much improved." Mechanistic manometry work shows both oils relax gastric and duodenal smooth muscle locally. The main side effect is reflux or a peppermint "burp," which the enteric coating largely prevents. This is the first supplement worth trying for the pain-predominant (epigastric pain syndrome) phenotype. The honest caveat: the trial program is small and several studies were manufacturer-sponsored.

STW 5 (Iberogast), 20 Drops Three Times Daily — Limited Evidence, Liver Caution

STW 5 is a standardized blend of nine herbal extracts (including bitter candytuft/Iberis amara, peppermint, chamomile, and licorice) that acts on several gastric targets at once—relaxing the fundus, tonicizing the antrum, and reducing acid and hypersensitivity. A pooled meta-analysis of three placebo-controlled trials found it more effective than placebo for the most bothersome GI symptom (odds ratio 0.22; 95% CI 0.11–0.47), and a fourth trial showed no significant difference versus the prokinetic cisapride. Reported tolerability is good, with adverse-event rates near placebo in the trials. The important safety caveat is post-marketing: rare but serious cases of drug-induced liver injury have been linked to STW 5, prompting regulators (including Australia's TGA in 2018) to require liver-warning label changes. Do not use it if you have liver disease, and stop immediately if you develop jaundice, dark urine, or right-upper-quadrant pain. The licorice component is a further reason to avoid open-ended use in people with hypertension.

Ginger, 1–1.2 g Daily — Limited (Postprandial-Distress Phenotype)

Ginger accelerates gastric emptying and stimulates antral contractions, which makes it most rational for the postprandial-distress (fullness and early-satiety) phenotype rather than the pain phenotype. In a small double-blind crossover RCT of 11 FD patients, 1.2 g of ginger sped gastric half-emptying (median 12.3 vs 16.1 minutes) and tended to increase antral contractions—but, tellingly, did not significantly change symptoms or gut peptides over that short window. So the physiology is real while the symptom evidence is thin: treat ginger as a reasonable, low-risk adjunct rather than a proven monotherapy. It pairs naturally with the nausea many FD patients report. Doses above ~3–4 g/day add little and can themselves cause heartburn.

Artichoke Leaf and Others — Weaker, Conditional

Artichoke leaf extract has positive but lower-quality trials in functional and overlapping biliary-type dyspepsia, working partly through a choleretic (bile-stimulating) effect; it is not in our database, so we mention it without a rating—reasonable to try if peppermint–caraway and STW 5 disappoint, but the evidence base is thin. Deglycyrrhizinated licorice (DGL) is popular for "stomach soothing" but has little controlled FD-specific evidence. If reflux overlaps with your symptoms, melatonin has small trials for functional heartburn, but it is not an FD treatment per se.

What Does Not Work, or Is Overhyped

Do not use peppermint oil if reflux or a hiatal hernia dominates—it relaxes the lower esophageal sphincter and can worsen heartburn. Avoid STW 5 entirely with existing liver disease given the hepatotoxicity signal, and avoid licorice-containing products if you have hypertension or take a thiazide/loop diuretic (pseudohyperaldosteronism risk). Skip high-dose ginger if you are on an anticoagulant without clinician sign-off. Bismuth and various "gut-soothing" blends, probiotics, and digestive enzymes are widely sold for FD but lack convincing controlled evidence in this specific disorder. And do not substitute any supplement for an H. pylori work-up or alarm-feature evaluation—weight loss, dysphagia, GI bleeding, or new dyspepsia after age 60 needs endoscopy, not a capsule.

How to Run the Protocol

Match the supplement to your phenotype. For epigastric pain, start enteric-coated peppermint–caraway oil twice daily, or STW 5 at 20 drops three times daily (if you have no liver disease); give either a 4-week trial. For postprandial fullness and early satiety, add ginger 1–1.2 g/day before meals. Keep H. pylori eradication, a PPI trial, and—where appropriate—a low-dose neuromodulator as the medical backbone; supplements are adjuncts. Re-evaluate at four weeks: if symptoms have not meaningfully improved, stop the supplement rather than stacking more, and revisit the diagnosis (including gastroparesis and rumination) with your clinician. Cutting caffeine, alcohol, and large fatty meals often does as much as any capsule.