Blood donation can reduce cardiovascular risk

Collecting blood for donation

New research published in BMC Medicine indicates that blood donation can have measurable benefits for patients with metabolic syndrome.

Investigators found that 2 sessions of blood donation were enough to improve blood pressure and markers of cardiovascular disease in patients with the syndrome.

Metabolic syndrome is characterized by obesity, insulin resistance, glucose intolerance, dyslipidemia, and hypertension. The condition is associated with an increased risk of diabetes and cardiovascular disease.

Because iron overload is also associated with hypertension and diabetes, researchers decided to test the effect of phlebotomy (to reduce iron stores) on patients with metabolic syndrome.

Andreas Michalsen, MD, of Charité-University Medical Centre in Berlin, and his colleagues compared patients who underwent phlebotomy (n=33) to patients who did not (n=31).

Patients in the phlebotomy group donated 300 mL of blood at the start of the trial. Four weeks later, they donated between 250 mL and 500 mL. The investigators evaluated patients 6 weeks after the second blood donation to allow plenty of time for blood volume to be replaced.

The team found that patients who donated blood had lower blood pressure than patients who did not. The reduction in systolic blood pressure was 18.3 ± 10.5 mmHg in the phlebotomy group and 0.2 ± 7.7 mmHg in the control group, resulting in a difference of -16.5 mmHg (P<0.001).

Similarly, there was a greater reduction in the homeostatic model assessment (HOMA) index in the phlebotomy group than in the control group. However, this difference was not significant. The HOMA index decreased from 4.8 ± 7.2 to 3.6 ± 2.7 in the phlebotomy group and from 4.5 ± 3.8 to 4.1 ± 3.6 in the control group, resulting in a difference of -0.7 (P=0.29).

The HOMA index did not indicate a significant increase in insulin sensitivity. But plasma glucose and HbA1C were significantly decreased in the blood donation group (P<0.001 for both).

The researchers also observed non-significant changes in low-density lipoprotein cholesterol (LDL-C) and HDL-C that favored the phlebotomy group. And this resulted in a significant improvement in the LDL/HDL ratio (P<0.01).

“Consecutive reduction in iron stores was able to improve markers of cardiovascular risk and glycemic control,” Dr Michalsen said. “Consequently, blood donation may prevent not just diabetes but also cardiovascular disease for the obese.”

Dr Michalsen and his colleagues did observe some adverse events in patients who donated blood, although none were classified as serious. Four patients experienced headaches that lasted a few hours, 3 had mild dizziness lasting 2 hours or less, and 1 patient had symptoms of fatigue that lasted a few days.

In spite of these events, all of the patients who underwent phlebotomy rated the experience “tolerable.” And 85% said it was “very tolerable.”

Taking the study results together, the researchers concluded that blood donation could be a suitable treatment for certain patients with metabolic syndrome. 

“Obviously, this treatment will not be suitable for people with anemia,” Dr Michalsen said. “However, for those eligible for treatment, blood donation may prevent escalation of their condition.”

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