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The Natural: IberogastTM for the gastrointestinal tract

By Karen Kier
Pharmacist on behalf of the ONU HealthWise team

The Natural was a 1984 movie based on the 1952 novel by Bernard Malamud about a naturally talented baseball player named Roy Hobbs.  The movie starred many famous actors including Robert Redford, Robert Duvall and Glenn Close. The movie was nominated for four Academy Awards. 

Many drugs originate from natural products including acetylsalicylic acid, which comes from the bark of the white willow tree.  The German multinational pharmaceutical and biotechnology firm known as Bayer AG was the first to launch acetylsalicylic acid in 1899 as their trademark product known as Aspirin. Bayer is still famous for aspirin today. 


Recently, Bayer AG has been advertising a natural product in the United States for gastrointestinal (GI) issues. The product is a combination of six natural products combined together under the brand name of IberogastTM. 

The United States and Germany have very different processes for handling natural products.  Legally in the United States, the FDA has very little authority to regulate natural products if they are considered a dietary supplement rather than a drug. In Germany, there is a scientific advisory board called the German Commission E who has expertise for approval of substances and products used in traditional, folk, and herbal medicines. The German Commission E publishes monographs detailing the science or evidence for these products. 

In the United States, you often see natural products being marketed as dietary supplements with the standard warning “these statements have not been evaluated by the FDA.” In addition, companies are not allowed to make claims about treating or curing any diseases with a dietary supplement.  Therefore, these products can come to market without evidence of effectiveness or safety.  The FDA works to ensure safety, accurate labeling, and quality manufacturing, but after the product is either imported or manufactured.  

The German Iberogast® product was manufactured in 1960 for digestive health and relief of functional dyspepsia (indigestion) and irritable bowel syndrome (IBS). The formulation of Iberogast® in Germany is known as STW 5 and contains 9 different herbs.  The STW 5 formulation has been studied extensively in patients with functional gastrointestinal disorders (FGID) including dyspepsia and IBS.  Evidence from very low-quality studies shows an onset of 15 minutes for the 9-herb formulation with improved symptoms in about one week.  

Why am I concerned over these commercials? There is an important difference between the German Iberogast® 9-herb formulation and the US IberogastTM 6-herb formulation.  Obviously. one has 9 herbs and the other has 6, but it is more than just the number.  The U.S. product has a different herbal profile than the German product.  The one common herb between the 2 is Iberis amara known as candytuft or Clown’s mustard plant. The flowering plant is native to Europe.  The formulations studied in human trials did contain Iberis amara, but the product was different from what is in the United States. 

In addition to Iberis amara, the U.S. product contains caraway oil, peppermint oil, lemon balm, licorice, and German chamomile.  The U.S. IberogastTM comes as liquid drops or softgels. Twenty drops in a drink or one softgel are to be taken 3 times per day before meals. The product boasts relief of occasional indigestion, fullness, heartburn, nausea, gas, and abdominal discomfort. It is important to note for occasional use and not using it chronically.  

The ONU Drug and Health Information Center uses an evidence-based professional database on herbal products known as NatMed Pro. This database evaluates the quality of evidence based on clinical studies for natural products.  NatMed Pro rated Iberis amara has a 5 out 10 with evidence for possible effectiveness for indigestion and possibly safe with short-term use.  It recommends avoiding use during pregnancy. 

NatMed Pro gives the Iberogast products a 2 out 10 for evidence of effectiveness and this is because the other 5 herbs have limited data.  In addition, there are some significant safety concerns. Peppermint relaxes the sphincter between the esophagus and the stomach causing heartburn. Licorice can increase blood pressure and make hypertension worse. The caraway, peppermint, German chamomile, and lemon balm ingredients have well documented drug interactions with prescription and over the counter medications. The U.S. IberogastTM product is not gluten-free and contains wheat, soy and tree nuts.  

If you are having gut issues, discuss this with a healthcare professional before trying a product with potential safety issues. Natural may not always be better. 

Contact ONU HealthWise Pharmacy (419-772-3784) for more information. ONU Healthwise is offering flu and COVID-19 vaccine clinics, Monday through Friday from 4:00 - 6:00 p.m. Please call for more information. 

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