Bloodletting — back to the future as beneficial medical treatment?

The use of leeches has made a comeback in medicine.

Could bloodletting be next?

In a recent issue of New Scientist magazine, British medical historian Lindsey Fitzharris describes how findings from a study published earlier this year suggest that the ancient practice of bloodletting — cutting open a vein to drain some blood from the body — might be beneficial for certain people who are obese.

I underline the word might because the study was small and has yet to be replicated. Still, that study and other research in this area is intriguing, especially given bloodletting’s long and (mostly) gruesome history.

Here’s Fitzharris’ description of the new research:

Many people who are overweight have a cluster of medical problems including high blood pressure, high cholesterol and poor control of blood sugar levels, which is a precursor to diabetes. Together these are known as “metabolic syndrome.”

While not one of the classic signs, another common symptom in metabolic syndrome is a high level of iron in the blood, which seems to be caused by a genetic predisposition combined with a diet high in red meat. While it is unclear how these factors interrelate, high iron seems to play a causal role in high blood pressure and poor blood sugar control. It has also been implicated in fatty liver disease, another condition in which an unhealthy diet plays a part.

When we give blood — typically up to 470 millilitres — it takes a few weeks for our blood iron levels to be restored. That raises the intriguing possibility that a key mediator of at least some of the harmful effects of obesity could be combated by the simple act of regularly siphoning off some blood.

It almost sounds too good to be true, but earlier this year, a study suggested it could, in fact be that easy. The trial involved 64 obese people with metabolic syndrome. Half had 300 millitres of blood withdrawn at the start of the trial and a further 250 to 500 taken a month later. Six weeks from the start, those who had undergone two bleedings had improved blood pressure cholesterol and glucose levels.

It is only one trial, of course, and a small short-term one at that — further work is needed to see if the effect is real. But the results chime with a couple of other small studies that show bloodletting benefits people with high blood pressure or diabetes.

One of the study’s authors, Dr. Andreas Michalsen of the Charite-University Medical Centre in Berlin, told Fitzharris that people with high iron levels and metabolic syndrome might want to consider becoming regular blood donors — an action, that he notes, would also help blood banks. (As is always the case, however, no one should do anything based solely on the findings of a single small study.)

Fitzharris’ article, which appears in the Nov. 17-23 issue of New Scientist, also contains fascinating details of the history of bloodletting (its association with the red-and-white-striped barber pole, for example, and its possible role in George Washington’s death). Unfortunately, the article is not available in full online, but you can find the magazine in many local libraries.