Table 1 Acupuncture treatment details based on the STRICTA 2010 checklist

1. Acupuncture rationale

1a) Style of acupuncture

- Manual acupuncture based on traditional meridian theory.

1b) Reasoning for treatment provided, based on historical context, literature sources, and/or consensus methods, with references where appropriate

- Manual acupuncture treatments based on the traditional meridian theory, clinical experience, and consensus by the experts in acupuncture and FD.

1c) Extent to which treatment was varied

- No additional acupoints allowed.

2. Details of needling

2a) Number of needle insertions per subject per session (mean and range where relevant)

- Fixed 13 acupoints.

2b) Names (or location if no standard name) of points used (uni/bilateral)

- LI 4, ST36, LR3, PC3, SP4, and ST34 (bilateral) and CV12 (unilateral).

2c) Depth of insertion, based on a specified unit of measurement or on a particular tissue level

- From 5 to 30 mm.

2d) Response sought (for example, de qi or muscle twitch response)

- De qi sensation

2e) Needle stimulation (manual, electrical)

- Manual stimulation: needle rotation with thumb and index fingers at 3 Hz.

2f) Needle retention time

- Fifteen minutes.

2 g) Needle type (diameter, length, and manufacturer or material)

- A sterilized stainless steel needle (0.2 × 40 mm, Dongbang Acupuncture Inc., Ungcheon, Boryeong, Korea).

3. Treatment regimen

3a) Number of treatment sessions

- Ten treatment sessions in both groups including two sessions during fMRI scanning.

3b) Frequency and duration of treatment sessions

- Twice weekly for 4 weeks plus additional two treatments during fMRI scanning (before and after treatment), 15 minutes for each session.

4. Other components of treatment

4a) Details of other interventions administered to the acupuncture group (moxibustion, cupping, herbs, exercises, lifestyle advice)

- No other interventions during the study period allowed.

4b) Setting and context of treatment, including instructions to practitioners, and information and explanations to patients

- Participants will be informed that the acupuncture treatment is based on traditional Korean medicine and previous studies on clinical trial.

5. Practitioner background

5) Description of participating acupuncturists (qualification or professional affiliation, years in acupuncture practice, other relevant experience)

- Korean medicine doctors who have license and at least 3 years of experience of treating gastrointestinal diseases. They have studied acupuncture for more than 10 years and graduated from a university of Korean medicine. To ensure providing identical treatments, they finished 10 hours of training and simulated the protocol.

6. Control or comparator interventions

6a) Rationale for the control or comparator in the context of the research question, with sources that justify this choice

- Streitberger needle will be used as a sham control (its rationale is described in background and discussion of main text).

6b) Precise description of the control or comparator. If sham acupuncture or any other type of acupuncture-like control is used, provide details as for items 1 through 3 above.

- Practitioners will use identical acupoints to sham group compared with real acupuncture group.

- The depth of insertion, response sought, needle stimulation, needle retention time, treatment period, and number of treatment sessions in sham group will be the same as those in real acupuncture group.

- In sham acupuncture group, Streitberger placebo needles (0.2 × 40 mm, Asia Med GmbH, Germany) will be used.