A special chiropractic adjustment can significantly lower high blood pressure, a placebo-controlled study suggests.

“This procedure has the effect of not one, but two blood-pressure medications given in combination,” study leader George Bakris, MD, tells WebMD. “And it seems to be adverse-event free. We saw no side effects and no problems,” adds Bakris, director of the University of Chicago hypertension center.

Eight weeks after undergoing the procedure, 25 patients with early-stage high blood pressure had significantly lower blood pressure than 25 similar patients who underwent a sham chiropractic adjustment. Because patients can’t feel the technique, they were unable to tell which group they were in.

X-rays showed that the procedure realigned the Atlas vertebra – the doughnut-like bone at the very top of the spine – with the spine in the treated patients, but not in the sham-treated patients.

Compared to the sham-treated patients, those who got the real procedure saw an average 14mm Hg greater drop in systolic blood pressure (the top number in a blood pressure count), and an average 8mm Hg greater drop in diastolic blood pressure (the bottom blood pressure number).

None of the patients took blood pressure medicine during the eight-week study.

“When the statistician brought me the data, I actually didn’t believe it. It was way too good to be true,” Bakris says. “The statistician said, ‘I don’t even believe it.’ But we checked for everything, and there it was.”

Bakris and colleagues report their findings in the advance online issue of the Journal of Human Hypertension.