Source: CTV News on CTV - Canadian television's online/Google

The practice of bloodletting - releasing some blood to compel the body to make more - has long been dismissed by the medical community as ancient history. But new research suggests it might actually be a simple and effective way to cut health risks in people who are obese.

Researchers in Germany conducted a randomized controlled trial on 64 obese volunteers who had a condition called metabolic syndrome, a cluster of symptoms that are known to increase the risk of heart disease. The symptoms include a large waist, high blood pressure, elevated blood glucose levels, high triglycerides and low levels of "good" LDL cholesterol.

The volunteers were broken up into two groups: 31 served as a control, while 33 donated blood twice: about 300 millilitres at the start of the trial; and between 250 and 500 ml after one month.

(A typical blood donation unit gathered by Canadian Blood Services contains 450 ml of blood and donors can donate every 56 days.)

Six weeks later, when the volunteers had normal blood volume again, the two groups were assessed. The patients who have donated blood showed:

    a significant drop in blood pressure
    lower resting heart rate
    lower blood glucose levels w
    a normalized ratio between LDL and HDL cholesterol was normalized.

The results appear in the journal BMC Medicine.

Even the lead researcher on the study, Professor, Dr.  Andreas Michalsen from the Charité-University Medical Centre in Berlin, says he was taken aback by the findings.

"We expected some blood pressure reduction, but not to this extent," he said, noting that the treated patients saw their systolic blood pressure drop from a median of 148 mmHg to 130 mmHg.

The researchers aren't sure why bloodletting appeared to have such a strong effect, but suspect it might have to do with blood iron. Excess iron has been tied to many metabolic syndrome symptoms and can lead to inflammation, which makes the symptoms worse.

When blood is withdrawn, the body pulls excess iron previously stored in various organs to use it to produce new red blood cells. 

Michalsen says more study is needed, but for people with metabolic syndrome, donating blood regularly might be a simple way to prevent the symptoms that can lead to heart disease. And, he notes, it would be a low risk treatment that anyone without anemia or bleeding disorders could use.

"This is a very simple treatment method, it is available everywhere, the costs are very low, and, on the other side, blood donations are needed in modern medicine," he tells CTV News.

Larger trials are needed to confirm the results and evaluate the long-term risks of such a treatment, Michalsen said.

Dr. Pieter Cohen, an assistant professor of medicine at Harvard Medical School and a general internist at Cambridge Health Alliance, said blood donation should not be recommended as a treatment for metabolic syndrome unless more studies are done.

"You want to know [that] it would make them live longer," or reduce the actual risk of heart attack and stroke, not just markers linked with those conditions, Cohen said.