Peppermint Oil for the treatment of Irritable Bowel Syndrome or Functional Abdominal Pain in Children:
the MINT study

Irritable bowel syndrome (IBS) and functional abdominal pain (FAP) are common
conditions in children. Every year, approximately 13,000 children in the
Netherlands visit the pediatrician with this complaint. IBS and FAP are
associated with a reduced quality of life and an increased risk of psychiatric
disorders. Therapeutic options include an explanation of the condition,
painkillers, often in combination with dietary modifications, or psychological
therapies such as hypnotherapy or cognitive behavioral therapy. Currently,
there is no proven effective pharmacological treatment for children with IBS or
FAP.

Peppermint oil is a very interesting therapeutic option to investigate further:
it relaxes smooth muscle tissue in vitro and modulates visceral nociception.
Two small studies of low quality in children suggest a positive effect on
abdominal pain. A systematic review from 2020 in adults with IBS and a
subsequently published Dutch study in adult IBS patients concluded that
peppermint oil capsules lead to a reduction of complaints. Peppermint oil is
therefore recommended in the recently published American treatment guideline
for adults with IBS.

Pediatricians therefore regularly recommend peppermint oil capsules to children
with FB or IBS, even though there is no convincing evidence of an effect in
children. For a long time, peppermint oil capsules were not registered for
children < 10 years and in that case, regular peppermints were often
prescribed, with positive reported effects. As mentioned, the effectiveness of
peppermint oil capsules in children has not been sufficiently studied and the
effect of peppermints on abdominal pain has not been studied at all. In the
first phase of formulating and planning this study, several (parents of)
children with abdominal pain were consulted about the study design. They
advised comparing peppermint oil capsules with both placebo capsules and
peppermints because both research questions are important in their view.

The aim of the Mint study is to investigate the effectiveness of peppermint oil
capsules compared to placebo capsules in reducing abdominal pain intensity in
these children. In addition, we investigate the effect of peppermint oil
capsules compared to placebo capsules on other disease-related outcome measures
such as anxiety & depression, quality of life, absenteeism from school, and
healthcare costs. The second aim is to explore the effectiveness of regular
mints in reducing abdominal pain intensity compared to peppermint oil capsules
and placebo capsules and the effect of mints on secondary outcome parameters.

Multicenter, partially blinded, placebo-controlled study consisting of 3 groups
(blinded peppermint oil capsules or placebo capsules and an open-label group
with regular mints) with a treatment duration of 8 weeks and a follow-up period
of 4 weeks.

Peppermint oil capsules 182 mg 2 d.d.1 capsules (8-11 years) or 3 d.d. 1
capsule (12-18 years) versus placebo capsules versus regular mints 2-3 times 1
day for 8 weeks

The subjects have to visit the pediatric department twice in 12 weeks.
Moreover, the subjects and their parents, separately, have to fill out
questionnaires and a pain diary on an app four times: (I) at the start of the
baseline period, (II) in the fourth week of the study (III) in the eight week
of the study (end of treatment), and (IV) four weeks after the end of
treatment. Patients will be randomly allocated to peppermint oil capsules,
placebo capsules, or peppermints. Also, a saliva swab will be taken for DNA
studies. Side-effects of peppermint oil capsules are generally mild and
transient of nature.