Licorice (Glycyrrhiza glabra). The internal use of licorice roots is recognized by Commission E to treat ulcers of the stomach and esophagus. Licorice facilitates the formation of mucus that lines the wall of the stomach and protects it against gastric juice. This plant is commonly recommended by naturopaths in cases of gastroesophageal reflux because of its protective effect on the mucosa and its anti-inflammatory properties. However, no clinical study has proven its effectiveness.

D-limonene. In 2007, two small-scale clinical trials (19 and 13 patients) demonstrated probable efficacy of d-limonene against gastroesophageal reflux in approximately 80% of participants.⁴.

The d-limonene would work by improving the peristalsis of the esophagus and by protecting the mucous membrane against stomach acid. It can be purchased as orange peel extracts (1 mg doses). Cures of 000 doses (one pill every two days) would improve symptoms.

Marshmallow, mallow, elm, mullein, nopal, plantain. Due to their high pectin and mucilage content, these plants have traditionally been used to relieve irritation of the mucous membrane that lines the digestive system.⁵. They act by protecting the tissues from acid attacks. No clinical studies seem to have been performed so far to support their use.