Functional dyspepsia (FD) is a functional gastrointestinal disorder without any structural lesion . It is reported that the prevalence of FD ranges from 8% to 23% in Asia , and in particular, FD is claimed to affect 25% of the South Korean population . Though FD is not a life-threatening disease, FD patients suffer from a poor quality of life (QoL), which is regarded as an economic burden on society .
Although various treatments for FD, such as proton pump inhibitors, prokinetic agents, tricyclic antidepressants, and antinociceptive agents are available [5–9], many FD patients turn to other complementary and alternative therapies largely due to a lack of satisfactory relief by these treatments .
Acupuncture treatment is one of the most sought-after therapeutic modalities in complementary and alternative medicine. It has been frequently used to treat symptoms of FD  largely based on the following rationales: firstly, acupuncture is well known to relieve pain in various conditions  and may help reduce epigastric pain or burning sensation ; secondly, previous studies have shown that manual acupuncture and electro-acupuncture modulates gastric/duodenal motility through the activation of sympathetic efferent nerve fibers or vagal nerve fibers ; finally, since patients with FD have been reported to have higher levels of psychological distress or depression than healthy subjects [14, 15], the anxiolytic or antidepressant effects of acupuncture have been utilized to minimize worsening of FD symptoms [16–18].
However, previous studies have reported inconsistent findings of the clinical benefit of acupuncture treatment for FD [4, 19]. Nevertheless, these studies have been criticized for adopting relatively sub-optimal acupuncture treatment, i.e., three times a week for 2 weeks [19, 20], or testing a less generalizable treatment regimen, i.e., daily acupuncture treatment for 4 weeks . According to a systematic review by Zhu , the acupuncture treatment for FD lacks high-quality evidence. Hence, it was addressed that randomized clinical trials corresponding with the CONSORT statement and STandards for Reporting Interventions in Clinical Trials of Acupuncture (STRICTA) recommendations have to be implemented to evaluate the efficacy of acupuncture for FD. In addition, considering the questions which have been raised so far on the adequacy of various sham acupuncture controls [22, 23], care should be taken before simply adopting any available sham devices or procedures in the early phase.
Given that FD is now regarded as a complex disorder of which the pathophysiological mechanisms are inconclusive , various factors are likely to come into play. Among them, ghrelin, an orexigenic peptide, has been shown to play an important role in gastric motility, food intake, and potential gastroprotection against acute gastric mucosal injury [25, 26]. However, it is yet to be studied whether ghrelin is associated with the mechanisms of acupuncture treatment in patients with FD [27, 28].
Taken together, we felt the need to properly test whether acupuncture treatment would help symptom improvement in FD patients and, subsequently, the related mechanism. Therefore, we propose a two-center, randomized, waitlist-controlled trial investigating the effectiveness of acupuncture for symptom improvement in patients with FD and to assess whether the change in ghrelin secretion is associated with acupuncture treatment.