Skip to main content

The Globe and Mail

Bloodletting may be a blessing for obese patients

It may seem like a throwback to medieval medicine, but regular bloodletting could be an extremely effective way to reduce the risks of heart disease and diabetes in people who are obese, new research suggests.

"I had expected some beneficial effects, but I was surprised by the very clear results," said the lead researcher, Andreas Michalsen from the Charité-University Medical Centre in Berlin. Patients who underwent bloodletting experience a significant improvement in their blood pressure, glucose levels and a reduction in other risk factors associated with cardiovascular disease.

The study included 64 obese volunteers with metabolic syndrome – a disorder linked to a large waist circumference. Fat inside the belly produces hormones and inflammatory chemicals that disrupt the body's ability to properly metabolize glucose and fat. It can lead to high blood pressure, elevated glucose levels and, potentially, increased levels of harmful fats in the blood stream. Left unchecked, metabolic syndrome doubles the risk of heart disease and increases fivefold the likelihood of developing Type 2 diabetes.

Story continues below advertisement

Patients with metabolic syndrome also tend to have high levels of iron, which can further aggravate their medical condition. "We need some iron, but if we have too much it can lead to inflammation and increased oxidation," factors which can also contribute to hypertension and diabetes, noted Dr. Michalsen.

So, the researchers sought to reduce the body's stores of iron through bloodletting. Red blood cells, which carry oxygen, contain a form of iron. Once some blood is withdrawn, iron previously stored in various organs is used for the production of new red blood cells.

For the study, 33 volunteers gave blood, while 31 served as a control group. About 300 millilitres were withdrawn at the start of the trial and between 250 and 500 ml were removed after one month.

Six weeks later, when ample time had passed for blood volume to return to normal, the two groups were assessed. The patients who gave blood were much better off, according to the findings published in the journal BMC Medicine. They showed a significant drop in systolic blood pressure (from 148 mmHg to 130 mmHg); heart rate and blood glucose levels were reduced; and there was a marked improvement in cholesterol levels.

Dr. Michalsen also noted blood donors generally felt much better.

Although these results will need to be confirmed with follow-up studies, Dr. Michalsen thinks regular blood donations could become part of the treatment program for metabolic syndrome.

There are several reasons why certain individuals have high iron levels. Some people are genetically prone to store up iron. Eating a diet with lots of red meat can contribute to the problem. And people with metabolic syndrome and hypertension often have above average levels.

Story continues below advertisement

"I would prefer that people would adopt a vegetarian lifestyle," but, he added, donating blood is also a safe and effective way to reduce iron stores. As a general rule, men can give blood every two months and women every three months, he said.

There's an added bonus of blood donations – the blood products can be used by other patients who need them. "This is a win-win," said Dr. Michalsen.

Report an error Licensing Options
Comments are closed

We have closed comments on this story for legal reasons. For more information on our commenting policies and how our community-based moderation works, please read our Community Guidelines and our Terms and Conditions.

Combined Shape Created with Sketch.

Globe Newsletters

Get a summary of news of the day

Combined Shape Created with Sketch.

Thank you!

You are now subscribed to the newsletter at

You can unsubscribe from this newsletter or Globe promotions at any time by clicking the link at the bottom of the newsletter, or by emailing us at