A small trial undertaken at one site in Kochi, Kerala has found that curcumin, the active ingredient of turmeric, has no anti-inflammatory property in people with rheumatoid arthritis.
The trial randomly assigned participants to receive either 2 grams of curcumin along with 10 mg of piperine a day (intervention arm) or a placebo. All patients were followed up every month for one year. It was a double-blind study where neither the participants nor the people conducting the trial knew who was receiving the intervention and who was getting the placebo.
A combination drug containing curcumin and piperine was given to the participants in the intervention arm. Bioavailability of curcumin is a major challenge, and it is to address this that piperine was given as piperine is known to improve curcumin bioavailability.
Each arm had 100 participants, and per protocol analysis included 92 and 93 participants in the curcumin and the placebo group, respectively. The primary objective of the trial was to study if curcumin could maintain remission in patients with rheumatoid arthritis during the study period of one year while the conventional drugs used for treating the disease were being withdrawn gradually one month after the trial began. The secondary objectives of the trial were to study the relapse rate, how soon the relapse occurred during the trial when the conventional drugs were being withdrawn and evaluate the bioavailability of the curcumin preparation. The results were published on August 31, 2023 in the journal Rheumatology International.
“The anti-inflammatory property of curcumin has been well documented in the lab on animals and in vitro studies,” says Dr. Padmanabha Shenoy, from the Centre for Arthritis and Rheumatism Excellence (CARE), Dr Shenoys Care in Kochi and the principal investigator of the trial and the corresponding author of the paper.
But the trial found that participants in the intervention arm who received curcumin-piperine combination drug did not show any statistical difference in remission compared with the placebo group. At the end of one year of follow-up, 52 participants in the treatment group did not face any disease relapse compared with 57 participants in the placebo arm. “We did not see more participants in the intervention group having relapse-free survival compared with the control group. Curcumin appeared to be no different from the placebo as far as relapse-free survival was concerned,” says Dr. Shenoy.
Similarly, there was no statistical difference in the median time to relapse in both the groups. If the median time to relapse was 219 days in the intervention arm, it was 214 days in the control group. “Importantly, the remission rates were similar in both the groups — 40% in the intervention arm and 36% in the control group,” says Dr. Shenoy.
The team studied if curcumin was bioavailable in those who received the combination drug of curcumin and piperine to see if similar outcomes in both the groups were despite good bioavailability of curcumin in participants in the treatment group. “The levels of curcuminoid, which is a curcumin metabolite, were significantly higher in the intervention arm. The control group had nil curcumin metabolite,” Dr. Shenoy says. The curcumin metabolite level was estimated in 72 of 92 in the intervention group and 70 of 93 in the placebo group. “The serum level of curcuminoids in the interventional arm was 19.70 nanogram/ml, while it was zero in the control arm,” he says.
He says it is not known if higher doses of curcumin might show an anti-inflammatory effect. But for the dosage tested (2 grams), which is the most commonly used one, curcumin had no effect in people with rheumatoid arthritis and was as good as a placebo.
