Curcumin for functional dyspepsia: a randomised, double blind trial … (with a significant flaw!)

This randomised, double blind controlled trial compared the efficacy of curcumin versus omeprazole in improving patient reported outcomes in people with dyspepsia.

The interventions were:

• curcumin alone (C),
• omeprazole alone (O),
• curcumin plus omeprazole (C+O).

Patients in the combination group received two capsules of 250 mg curcumin, four times daily, and one capsule of 20 mg omeprazole once daily for 28 days.

Main outcome measure was unctional dyspepsia symptoms on days 28 and 56, assessed using the Severity of Dyspepsia Assessment (SODA) score. Secondary outcomes were the occurrence of adverse events and serious adverse events.

A total of 206 patients were enrolled in the study and randomly assigned to one of the three groups; 151 patients completed the study. Demographic data (age 49.7±11.9 years; women 73.4%), clinical characteristics and baseline dyspepsia scores were comparable between the three groups. Significant improvements were observed in SODA scores on day 28 in the pain (−4.83, –5.46 and −6.22), non-pain (−2.22, –2.32 and −2.31) and satisfaction (0.39, 0.79 and 0.60) categories for the C+O, C, and O groups, respectively. These improvements were enhanced on day 56 in the pain (−7.19, –8.07 and −8.85), non-pain (−4.09, –4.12 and −3.71) and satisfaction (0.78, 1.07, and 0.81) categories in the C+O, C, and O groups, respectively. No significant differences were observed among the three groups and no serious adverse events occurred.

The authors concluded that curcumin and omeprazole had comparable efficacy for functional dyspepsia with no obvious synergistic effect.

This study, which was funded by the Thai Traditional and Alternative Medicine Fund, has been picked up by the press and is being lauded as a solid proof of efficacy. Its authors too are not half proud of their splendid trial:

This multicentre randomised controlled trial provides highly reliable evidence for the treatment of functional dyspepsia. PPIs, widely used and approved for over-the-counter use, were compared with curcumin, a popular herbal remedy. The study design, including double blind randomisation, minimised biases. Participants met strict criteria, underwent endoscopy and were tested for H pylori infection. Furthermore, we implemented measures to minimise biases by ensuring that the individuals administering the drugs, participants receiving the drugs and individuals conducting the assessment remained blinded to the type of medications administered to the participants. The trial was carried out in hospitals, and certified individuals used standardised questionnaires for assessments. Statistical methods were appropriate and followed accepted principles.

Two follow-up appointments were scheduled, and blood tests showed no abnormal symptoms or liver function abnormalities. However, participants with high body mass index indicated a trend towards liver function impairment in the curcumin group, suggesting the need for larger studies. Some participants did not provide follow-up information, which is a study weakness. However, the number of participants who provided this information was sufficient for statistical analysis and the majority of the participants attended the follow-up visit. Therefore, it can be deduced from the results that even if the number of participants followed after drug administration increased, the study findings would not be significantly different. Another limitation of this study was the absence of long term follow-up data for all patients after treatment. This is a question that will require further investigation.

The strength of the study lies in its relevance to daily clinical practice, providing additional drug options in addition to PPIs alone, without added side effects. The study was unbiased, partially funded by government organisations and the first well designed trial comparing curcumin with PPI for functional dyspepsia, with confirmation through endoscopy and ruling out H pylori infection. Limitations of this study included the small number of patients who were lost to follow-up and the lack of long term follow-up data.

However, I am far less impressed.

Why?

Curcumin is bright yellow and has a very distinct taste/smell. Even though curumin was given in capsules, patients can easily tell what they are taking. I therefore doubt that they were adequately blinded. In fact, the authors seem to agree when they state the following: