According to the National Institutes of Health’s Dietary Supplements Label Database, there were nearly 56,000 dietary supplement products available for sale in the United States in January 2019. One study estimated that 52% of adults in the U.S. use some form of dietary supplement, while another estimated a staggering 90% of patients with gastrointestinal illness take dietary and herbal supplements.

But how should gastroenterologists counsel patients about the use of dietary supplements?

Three gastroenterologists with nutritional expertise addressed that question in an AGA session on Monday, May 20, at DDW^® 2019 in San Diego, CA.

Jost Langhorst, MD, a pioneer in the field of integrative gastroenterology, said the widespread availability and use of dietary supplements makes the question impossible to ignore.

“The role of the contemporary practitioner is to communicate the current evidence to enable patients to make safe, informed choices on their use,” said Dr. Langhorst, professor and chair of integrative medicine at Klinikum Bamberg in Bamberg, Germany. “Unfortunately, in many cases, there remains a lack of evidence to support or refute a benefit of many dietary and herbal supplements.”

Despite the lack of robust evidence, Dr. Langhorst said there are proven benefits for many dietary supplements and some evidence for their use.

For ulcerative colitis (UC), there’s evidence to suggest that curcumin may be effective for inducing remission and preventing relapse when combined with 5-aminosalicylic acid, he said. Myrrh, coffee charcoal and chamomile may also be effective for maintaining remission of UC, while psyllium may be effective for maintaining UC remission due to increased butyrate production.

For irritable bowel syndrome (IBS), peppermint oil capsules have shown to be safe and effective for relieving symptoms and abdominal pain, while iberogast has also proven effective in alleviating symptoms and abdominal pain, Dr. Langhorst said. Iberogast, or STW 5, is a liquid herbal supplement comprised of nine herbal extracts. The efficacy of STW 5 for alleviating IBS symptoms and abdominal pain has been demonstrated in multiple observational studies and in one double-blind, randomized, placebo-controlled trial.

Psyllium has also proven effective for alleviating IBS symptoms, constipation in particular. And probiotics may relieve IBS symptoms and abdominal pain, although ideal bacterial strains have not been established, he said.

Dr. Langhorst shared three examples from his own practice of patients who benefit from taking dietary supplements. One of his Crohn’s disease patients, who is stable on her medication but suffers from arthritis joint pain, takes frankincense to relieve the pain. Another patient with UC is able to control her symptoms with bilberry juice supplementation, and a third takes probiotics to relieve his IBS symptoms.

“Beyond the need to treat nutritional deficiencies, evidence continues to build for the use of selected dietary supplements and other complementary forms of therapy for the prevention, treatment and management of gastrointestinal illnesses,” Dr. Langhorst said. “But to be able to recommend their use in practice, we need more robust evidence on therapeutic benefits, quality standards for ingredients used, and independent regulation, ideally prior to market entry.”

Berkeley Limketkai, MD, PhD, associate clinical professor in the Vatche and Tamar Manoukian Division of Digestive Diseases at the University of California, Los Angeles, School of Medicine, agreed with Dr. Langhorst that there’s a theoretical benefit to many dietary supplements. But he said those benefits are often based on shaky evidence, insufficient evidence, contradictory evidence or a complete lack of evidence.

“Lack of evidence does not mean lack of relationship, but lack of evidence also does not mean license to claim anything,” he said. “It’s easy to make wild or overstated claims, but many claims may have a theoretical mechanistic basis. I do not believe that all claims are false and my position is not to say that everything is purely bogus. But we should at least be vigilant about how we evaluate the evidence so we can separate the hope from the hype.”

Gerard E. Mullin, MD, MS, AGAF, associate professor in the division of gastroenterology at Johns Hopkins University School of Medicine in Baltimore, MD, moderated the session and sat down with DDW News to discuss the use of dietary supplements in the practice of gastroenterology and controversy surrounding the efficacy and potential harm of probiotics.