Turmeric is derived from the root of the Curcuma longa plant. It contains a naturally active compound called curcumin thought to have anti-inflammatory and antimicrobial properties, and has long been used as a medicinal remedy, including for the treatment of indigestion, in South East Asia.
But it's not clear how well it compares with conventional drugs for this indication, largely because there have been no head to head studies.
The researchers therefore randomly assigned 206 patients aged 18-70 with recurrent upset stomach (functional dyspepsia) of unknown cause, recruited from hospitals in Thailand between 2019 and 2021, to one of three treatment groups for a period of 28 days.
These were: turmeric (two large 250 mg capsules of curcumin 4 times a day) and one small dummy capsule (69 patients); omeprazole (one small 20 mg capsule daily and two large dummy capsules 4 times a day (68 patients); and turmeric plus omeprazole (69 patients).
Omeprazole is a proton pump inhibitor, or PPI for short. PPIs are used to treat functional dyspepsia, the symptoms of which include feeling excessively full after food (postprandial fullness), feeling full up after only a little food (early satiety), and pain and/or burning sensation in the stomach and/or food pipe (epigastric pain).
But long term use of PPIs has been linked to increased fracture risk, micronutrient deficiencies, and a heightened risk of infections, note the researchers.
Of the 206 patients enrolled, 151 completed the study, with 20 in the curcumin group;19 in the omeprazole group; and 16 in the combined treatment group, dropping out.
Patients in all three groups had similar clinical characteristics and indigestion scores, as assessed by the Severity of Dyspepsia Assessment score or SODA, at the start of the trial. Patients were reassessed after 28 days and then again after 56 days.
SODA scores indicated significant reductions in symptom severity by day 28 for pain (-4.83, -5.46 and -6.22) and other symptoms (-2.22, -2.32, and -2.31) for those in the combined, curcumin alone, and omeprazole alone groups, respectively.
These improvements were even stronger after 56 days for pain (-7.19, -8.07 and -8.85, respectively) and other symptoms (-4.09, -4.12 and -3.71, respectively).
SODA also captures satisfaction scores: these scarcely changed over time among the curcumin users, which might possibly be related to its taste and/or smell, suggest the researchers.
No serious side effects were reported, although liver function tests indicated some level of deterioration among curcumin users carrying excess weight, note the researchers.
They acknowledge the small size of the study, as well as several other limitations, including the short intervention period and lack of long-term monitoring data. Further larger, long term studies are needed, they say.
Nevertheless, they conclude: "This multicentre randomised controlled trial provides highly reliable evidence for the treatment of functional dyspepsia," adding that "the new findings from our study may justify considering curcumin in clinical practice."
Kongkam P, Khongkha W, Lopimpisuth C, Chumsri C, Kosarussawadee P, Phutrakool P, Khamsai S, Sawanyawisuth K, Sura T, Phisalprapa P, Buamahakul T, Siwamogsatham S, Angsusing J, Poonniam P, Wanaratna K, Teerachaisakul M, Pongpirul K.
Curcumin and proton pump inhibitors for functional dyspepsia: a randomised, double blind controlled trial.
BMJ Evid Based Med. 2023 Sep 11:bmjebm-2022-112231. doi: 10.1136/bmjebm-2022-112231