This study aims to investigate changes in gastric motility (including gastric accommodation), nutrient volume tolerance, gastric emptying and gastrointestinal hormones in healthy volunteers after an acute intake of a combination of peppermint oil and caraway oil, compared to placebo. In addition, the effect of a combination of peppermint oil and caraway oil on appetite-related sensations and upper gastrointestinal symptoms will be assessed.

Gastric emptying rate will be assessed using a 13C breath test. Intragastric pressure (IGP) will be measured using high-resolution manometry in fasted state and during intragastric infusion of a nutrient drink (350 mL or until full satiation). Appetite-related sensations and gastrointestinal symptoms were rated during IGP measurements. Blood samples were collected to assess peptide hormone levels.

This study aims to investigate changes in gastric motility (including gastric accommodation), nutrient volume tolerance, gastric emptying and gastrointestinal hormones in healthy volunteers after an acute intake of a combination of peppermint oil and caraway oil, compared to placebo. In addition, the effect of a combination of peppermint oil and caraway oil on appetite-related sensations and upper gastrointestinal symptoms will be assessed. These outcomes will be studied on 2 study days. On study day 1, gastric emptying rate will be assessed using a 13C breath test 30 minutes after intake of study medication. This test is followed by an intragastric pressure (IGP) measurement during which 350 mL of a nutrient drink will be intragastrically infused 30 minutes after intake of study medication. On the second study day, IGP will be measured in fasted state for 4 hours after intake of study medication. Hereafter, a second dose of study medication will be administered. Thirty minutes later, a nutrient drink will be infused until the participant is fully satiated. Appetite-related sensations and gastrointestinal symptoms will be rated during IGP measurements on a 100mm VAS. Blood samples will be collected to assess peptide hormone levels.

Inclusion Criteria:

• Subject is male or female between 18 and 50 of age.
• Subject has a BMI between 20 and 25 and has a stable body weight for at least 3 consecutive months at start of study and no history of behavioral, therapeutic or surgical treatment aiming at or leading to weight loss/gain.
• Women of child-bearing potential agree to apply during the entire duration of the trial a highly effective method of birth control, which is defined as those which result in a low failure rate (i.e., less than 1% per year) when used constantly and correctly such as implants, injectables, combined oral contraceptive method, or some intrauterine devices (IUDs), sexual abstinence, or vasectomized partner. Women of non-childbearing potential may be included if surgically sterile (tubal ligation or hysterectomy) or postmenopausal with at least 2 year without spontaneous menses.
• Subject understands the study procedures and agrees to participate in the study by giving written informed consent.

Exclusion Criteria:

• Subject is under age of legal consent, pregnant or breastfeeding.
• Subject with a BMI ≤ 20 or BMI ≥ 25.
• Subject has current symptoms or a history of gastrointestinal or other significant somatic or psychiatric diseases or drug allergies.
• Subject has a significant heart, lung, liver or kidney disease.
• Subject has any history of a neurological disorder.
• Subject has a history of abdominal surgery. Those having undergone a simple appendectomy more than 1 year prior to the screening visit may participate.
• History or current use of drugs that can affect gastrointestinal function, motility or sensitivity or gastric acidity.
• History or current use of centrally acting medication, including antidepressants, antipsychotics and/or benzodiazepines (in the last year before screening visit).
• Subject consumes excessive amounts of alcohol, defined as >14 units per week for women and >21 units per week for men.
• Subject is currently (defined as within approximately 1 year of the screening visit) a regular or irregular user (including "recreational use") of any illicit drugs (including marijuana) or has a history of drug (including alcohol) abuse. Further, patient is unwilling to refrain from the use of drugs during this study.
• High caffeine intake (> 500 ml coffee daily or equivalent).
• Inability or unwillingness to perform all of the study procedures, or the subject is considered unsuitable in any way by the principal investigator.
• Recent participation (<30 days) or simultaneous participation in another clinical study.
• Radiation exposure exceeding 1mSv during the last year (from other studies or medical procedures).
• Subject has had a PET-scan or CT-scan in the last year.