Heartburn is as common gastrointestinal symptom experienced by otherwise healthy adults and typically manifests as a painful burning sensation in the upper abdomen or in the chest. Typically, heartburn symptoms are treated with over-the-counter (OTC) medications which may come with side effects.

There is suggestive evidence of the efficacy of fermented soy (Gastro-AD®) for the heartburn symptom relief. The aim of the study is to evaluate the effect of a fermented soy on heartburn symptom relief and time to onset.

Heartburn is as common gastrointestinal symptom experienced by otherwise healthy adults and typically manifests as a painful burning sensation in the upper abdomen or in the chest. Usually it is caused by the regurgitation of gastric acid into the esophagus. The prevalence of heartburn is 10-20% worldwide and is increasing. Typically, heartburn symptoms are treated with over-the-counter (OTC) medications which may come with side effects.

Gastro-AD® is a commercially available food supplement produced by fermentation of soy by a specific strain of Lactobacillus. There is suggestive evidence, in vivo as well as in vitro studies, of the efficacy of fermented soy (Gastro-AD®) for the heartburn symptom relief. The aim of the study is to evaluate the effect of a fermented soy on heartburn symptom relief and time to onset. It is hypothesized that the consumption of 1-3 g of fermented soy will relieve the heartburn symptom severity.

Inclusion Criteria:

• Able to provide written informed consent in English.
• Willing to have height and weight measured and provide demographic information (e.g. age, race, sex)
• Experience heartburn symptoms at least 2 days a week during the past 3 months.
• Use OTC product(s), supplements, or dietary manipulation to relieve heartburn symptoms in the last 3 months.
• Willing to take the study soy supplement before resorting to OTC product(s) to control heartburn symptoms.
• Willing to complete questionnaires, records, and diaries associated with the study and to complete all clinical visits.
• Willing to provide information about dietary intake; 3-day online 24-hr recalls during baseline, intervention, and washout.
• Willing and able to provide a valid social security for study payment purposes.

Exclusion Criteria:

• Do not meet the above criteria.
• Soy allergy
• Severe heartburn problem (cannot be ignored and often limits your concentration on daily activities) during the last week
• Diagnosed or currently being treated for any gastrointestinal diseases including GERD, gastric ulcers, Crohn's, celiac, ulcerative colitis, etc.
• Self-disclosed as pregnant or breast-feeding or planning on becoming pregnant during the study duration.
• Currently participating in another clinical study.

This is a double-blind study; the sponsor representative involved in the study, the investigator, the participants or site personnel involved in participant management or outcome assessment will remain blinded. Blinding to intervention will be used to reduce bias during data collection and evaluation of outcomes. At the investigational site, the randomization codes will remain secure at all times, but may be accessed in the event of an emergency.