Overview

The goal of this clinical trial is to learn if the food supplement containing a postbiotic (inanimate) Limosilactobacillus reuteri DSM 17648 works to improve the symptoms of upper gastrointestinal discomfort in healthy adults. The main questions it aims to answer are:

1. Does L. reuteri DSM 17648 reduce the frequency of the symptoms of upper gastrointestinal discomfort, including acid reflux-related and dyspeptic symptoms, and its relief rate, over 8 weeks of intake?
2. Does L. reuteri DSM 17648 improve gastrointestinal-related quality of life, and perceived stress?
3. How well do participants tolerate the L. reuteri DSM 17648 supplement?
4. Does L. reuteri DSM 17648 have an effect on the gut microbiota? (Exploratory aim)

Researchers will compare supplement containing L. reuteri DSM 17648 to a placebo (a look-alike supplement capsule that contains no L. reuteri DSM 17648).

Participants will:

• Take L. reuteri DSM 17648 supplement or a placebo every day for 8 weeks
• Answer questionnaires once every 2 weeks
• Provide stool samples for microbiome assessment at 2 timepoints (baseline and end of study (8 weeks))
• provide weekly information on investigational product intake and any adverse event records

Eligibility

Inclusion Criteria:

1. Be male or female.
2. Anyone with a BMI less than or equal to 32 kg/m².
3. Be aged 30-70.
4. Anyone currently experiencing occasional upper gastrointestinal discomfort (approximately 2 times/week over the past month), including the following:
   1. Heartburn
   2. Upper abdominal pain
   3. Reflux
   4. Pain or burning in the stomach
5. Anyone with an FSSG (Frequency Scale for the Symptoms of GERD) total score of 8 or

   above.

6. Anyone who is generally healthy - does not live with any uncontrolled chronic health conditions, such as cancer, mental health disorders, history of serious illness in the last three months, history of substance abuse, or planned surgery during the study period.
7. Willing to avoid introducing any new supplements, over-the-counter medications, or herbal remedies for the duration of this trial
8. If taking other supplements, over-the-counter medications, or herbal remedies unrelated to gut health, has been doing so consistently for a minimum of three months.
9. Willing to maintain current diet, sleep pattern, and activity levels for the duration of the trial.
10. Resides in the United States.

Exclusion Criteria:

• 1. Anyone with any allergies or sensitivities to any of the study product ingredients. 2. Any women who are pregnant, breastfeeding, or trying to conceive (or who will be at any point during the study period). 3. Anyone unwilling to follow the study protocol. 4. Anyone taking any supplement, over-the-counter medication, or herbal remedy targeting gut health. 5. Anyone with a known history of severe digestive disorders like GERD (Gastroesophageal Reflux Disease) and FD (Functional Dyspepsia), Irritable Bowel Syndrome (IBS), Irritable Bowel Disease (IBD), Crohn's disease, celiac disease, chronic constipation, chronic diarrhea, or gastrointestinal tract disorders or surgeries. 6. Anyone currently or recently (within the past 2 weeks) taking probiotic foods, including yoghurts. 7. Anyone currently or recently (within the last 12 weeks) taking medication, including proton pump inhibitors, anticoagulants, antihypertensives, anxiolytics, antidepressants, chemotherapy, immunotherapy, sedative hypnotics, medications that warn against grapefruit consumption, corticosteroids at doses greater than 5 mg per day, diabetic medications, oral anti-infectives (antibiotics, antifungals, antivirals) to treat an acute infection, antipsychotics, monoamine oxidase inhibitors (MAOIs), or thyroid products. 8. Currently partaking in another research study or will partake in any other research study for the next eight weeks or at any point during this study's duration.