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Western herbalism

Bitter candytuftIberis amara

The main extract in Iberogast. As a single extract it did not beat placebo in 53 people with IBS, while the whole formula did (208 people in total).

Botanical name
Iberis amara
Part used
whole flowering plant, extracted fresh
Also called
Candytuft, Iberis, Iberidis amarae herba (pharmacopoeia name)
Used in
Western herbalism
Taken for
Indigestion, Bloating, Cramping and pain
Sold as
tincture, extract, capsules

What is meant by bitter candytuft

Bitter candytuft, Iberis amara, is a small annual of the cabbage and mustard family with clusters of white flowers. It is the main plant extract in Iberogast, the liquid herbal product also known as STW 5, where it is prepared as a fresh-plant extract. In the von Arnim trial the product was described as mainly comprising a fresh plant extract from Iberis amara.

Outside that product, bitter candytuft is hard to find. We could not locate a European Medicines Agency monograph for it, and almost all human research on it comes from trials of the finished formula. Some supplement blends list it as an ingredient alongside other bitter herbs.

The plant belongs to the same family as cabbage, mustard and radish and produces glucosinolates and cucurbitacins, bitter compounds that Dong and colleagues describe as insect deterrents in this species.

In the traditions

Western herbalism

Bitter candytuft belongs to German phytotherapy rather than to a long folk tradition. The multi-herb liquid built around it has been in clinical use in Europe for more than five decades, as reviews of STW 5 note, for functional dyspepsia and irritable bowel syndrome. We found no European or WHO monograph for the plant on its own.

What the plant contains

Bitter candytuft is a source of glucosinolates and cucurbitacins. In rats, an Iberis amara extract lowered swelling and the inflammatory messengers TNF-alpha, IL-1 beta and prostaglandin E2 in an arthritis model. In a human esophageal cell line, the extract alone strongly increased release of the inflammatory messenger IL-8, while the whole nine-herb formula lowered it, which Ulrich-Merzenich and colleagues take to show that its partner herbs shape the net effect. Weidner and colleagues report that the extract induced reactive oxygen species and inhibited colon cancer cells in the laboratory. All of this is laboratory or animal work.

What has been tested in people

Almost all human evidence is of the finished formula, not the plant alone, and the one trial that separated them is informative. Madisch and colleagues randomized 208 people with irritable bowel syndrome to the nine-herb STW 5 (51 people), the six-herb STW 5-II (52), a bitter candytuft mono-extract (53) or placebo (52). Both formulas beat placebo for abdominal pain (P=0.0009 and P=0.0005) and symptom score (P=0.001 and P=0.0003) at 4 weeks, while the candytuft extract alone did not (P=0.1473 for pain, P=0.1207 for symptom score). Candytuft alone was therefore not shown to work in that trial.

For functional dyspepsia, von Arnim and colleagues randomized 315 people to nine-herb STW 5 at 3 x 20 drops a day or placebo for 8 weeks; symptom score improved 6.9 against 5.9 points (P less than 0.05). A different Madisch trial of 120 people found complete symptom relief after 8 weeks in 43.3 percent on STW 5-II against 3.3 percent on placebo. Vinson and colleagues randomized 272 people to STW 5-II for 8 weeks: response was 61.2 percent against 45.1 percent (P=0.008). A patient-level pooling of four STW 5-II trials (613 people) found the symptom sum score improved by 1.74 at 4 weeks and 2.07 at 8 weeks.

We found no trial of the candytuft extract on its own in functional dyspepsia, and no dose-response work for it.

StudyDoseWhat it found
Randomized trial, 208 people with IBS: STW 5, STW 5-II, candytuft mono-extract (n=53) or placebo PMID 149843734 weeks of treatmentBoth formulas beat placebo for pain and symptom score; candytuft alone did not (P=0.1473 pain, P=0.1207 symptom score)
Randomized placebo-controlled trial of nine-herb STW 5, 315 people with functional dyspepsia PMID 175310133 x 20 drops a day for 8 weeksSymptom score improved 6.9 points vs 5.9 on placebo (P<0.05)
Randomized placebo-controlled trial of six-herb STW 5-II, 120 people with functional dyspepsia PMID 14755152Three 4-week treatment blocksComplete relief after 8 weeks in 43.3% on active treatment vs 3.3% on placebo
Randomized placebo-controlled trial of STW 5-II, 272 people with functional dyspepsia PMID 386994718 weeks of treatmentResponse 61.2% vs 45.1% on placebo (P=0.008)
Patient-level meta-analysis of four STW 5-II trials, 613 people PMID 382461344 and 8 weeks of treatmentSymptom sum score improved by 1.74 at 4 weeks and 2.07 at 8 weeks vs placebo

Doses used in trials and traditional preparations

We found no dose of bitter candytuft extract alone that has been tested in a trial that worked. The formula trials used 3 x 20 drops a day of nine-herb STW 5 for 8 weeks (von Arnim), and a single 1.1 ml dose of Iberogast was used in the healthy-volunteer study by Pilichiewicz and colleagues. The share of candytuft extract in each dose is set by the manufacturer. The candytuft mono-extract in the Madisch irritable bowel trial is not given a dose in its abstract.

Treat these figures as a record of what was studied. Whether any amount of bitter candytuft suits a particular person is a question for a clinician or pharmacist who knows their history.

Safety

In the trials of the formulas, adverse events were similar to placebo. Melzer and colleagues found no serious adverse events in their pooling of STW 5 trials, and Andresen and colleagues found no difference between STW 5-II and placebo in treatment-related or severe adverse events. The nine-herb version also contained greater celandine, and Leroy and colleagues report a 32-year-old woman with severe acute hepatitis, jaundice and itching attributed to the product, who recovered within 5 weeks of stopping it; the six-herb version removed celandine. We found no safety study of candytuft on its own and no data on pregnancy, breastfeeding or children for the plant alone.

Drug interactions

We found no formal interaction study of bitter candytuft or of Iberogast in people in the sources we read. The formula contains several herbs, and the non-candytuft partners, which include licorice in both versions, each have their own interaction record on the relevant entries. Any statement about the formula’s interactions would be extrapolation from those partner herbs rather than a result for candytuft.

Products in the catalog with bitter candytuft

These catalog entries list bitter candytuft or one of its preparations among their active ingredients. Each page shows the amount on the label, the trials behind it and what buyers report.

Iberogast Liquid Drops 4.1 out of 5 from 421 ratings from Walmart · $4.30 per 20 mL bottle

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Related herbs

Western Angelica Angelica archangelica Western Chamomile Matricaria chamomilla (syn. Matricaria recutita) Western Peppermint Mentha x piperita Ayurvedic / TCM / Western Licorice Glycyrrhiza glabra Western Lemon balm Melissa officinalis

Common questions

Did bitter candytuft alone work in a trial?

Not in the one trial that tested it alone. In 208 people with irritable bowel syndrome, the nine-herb and six-herb formulas beat placebo, but the bitter candytuft extract alone did not (P=0.1473 for pain, P=0.1207 for symptom score).

What do the Iberogast trials show?

In 315 people with dyspepsia, nine-herb STW 5 improved a symptom score by 6.9 points against 5.9 on placebo over 8 weeks. In 272 people, six-herb STW 5-II gave a 61.2 percent response against 45.1 percent. These are trials of the formula, not of candytuft alone.

Is Iberogast the same as bitter candytuft?

No. Bitter candytuft is the main extract in Iberogast, which contains nine herbs in its original form and six in the later version. Results for the formula cannot be credited to one herb.

Why did the formula drop herbs?

The later six-herb version removed angelica, milk thistle and greater celandine. A case report links the nine-herb product, which contained celandine, to acute liver injury in a 32-year-old woman, though trials found adverse events similar to placebo.

Sources