Scientists at the Charité Hospital in Berlin recently undertook a clinical study to test the benefits that bloodletting can have on obese people suffering from the metabolic syndrome, with symptoms including high blood pressure, high blood-sugar levels and excessive iron in their blood.

After withdrawing two vials of blood from patients with the syndrome, scientists compared the samples with patients from a control group, according to head researcher Andreas Michalsen. They noticed "a significant reduction of blood pressure" among the participants after four to six weeks, he told DW.

Inspired by old traditions

The German study was inspired by an old medical tradition - people with high blood pressure or those at high risk of having a stroke often had blood drawn from their bodies.

The practice dates back to ancient Roman times, according to Lindsay Fitzharris, a medical historian with Wellcome Trust in the United Kingdom.

"Galen, a Roman physician in the 2nd Century A.D., believed blood was the product of food, so that when we eat, food is processed in the stomach and then moves into the liver, where it is processed as blood," says Fitzharris.

Galen, she adds, also believed that the excess blood needed to be removed from the body to restore "harmony and balance."

Dangerous practice

Although Galen's medical thinking has long been discarded by the medical community, Fitzharris argues he was definitely onto something – despite the risks patients were subjected to in those times.

Bloodletting frequently occurred in unsanitary conditions, making it extremely dangerous for anyone receiving the treatment. The instruments used to perform the procedure were often not clean, and the infection rates were high.

"Most of the time, bloodletting actually ended up hurting the sick rather than curing them," says Fitzharris. Often, she adds, those performing the procedure would cut the skin too deeply, allowing a patient to lose large amounts of blood.

Marathon bloodletting procedures

History books tell grotesque stories of marathon bloodletting procedures that often ended in a patient's death.

George Washington, the first President of the United States, is perhaps the most famous case of a bloodletting procedure gone wrong - Washington ended up dying.

Today's modern blood-withdrawal practices, however, have far higher hygiene standards. And given the results of the study, Michalsen now recommends using the procedure for certain patients.