People taking pills to treat medical conditions may report health improvements even if they know they're being given placebos, a new study suggests.
The placebo effect refers to the benefits experienced by patients taking placebo pills - made from sugar - during drug trials.
In such trials patients are not told whether they are taking real pills or placebos with no active ingredients, to ensure the medical benefits of a potential new drug are assessed rigorously.
But a small-scale study, published today in the science journal PLoS ONE, found placebos may work even without the deception.
Harvard Medical School associate professor of medicine Ted Kaptchuk and his team conducted a three-week trial of 80 patients suffering from irritable bowel syndrome.
They were divided into two groups, with one group given no pills, and the other given pills honestly described as “like sugar pills”. They were told to take the pills twice daily.
Nearly twice as many patients treated with the placebos reported adequate symptom relief (59 per cent) compared with the group taking no pills (35 per cent), according to the study.
The study claimed patients taking the placebo doubled their rates of improvement to a degree roughly equivalent to the effects of the most powerful irritable bowel syndrome medications.
“Not only did we make it absolutely clear that these pills had no active ingredient and were made from inert substances, but we actually had 'placebo' printed on the bottle,” Associate Professor Kaptchuk said in a statement.
“We told the patients they didn't have to even believe in the placebo effect – just take the pills.”
Although the study was limited in scope and would need to be confirmed by further research, he said the findings suggested there “may be significant benefit to the very performance of medical ritual”.
Senior study author Anthony Lembo, of the Harvard Medical School, said he was surprised with the results.
“I didn't think it would work,” he said.
“I felt awkward asking patients to literally take a placebo. But to my surprise, it seemed to work for many of them.”
The study was funded by Harvard Medical School's Osher Research Center and by the National Center for Complementary and Alternative Medicine in the United States.