Evaluating barberry supplements for hypertension

This clinical trial looked at the effect of barberry on patients with high blood pressure. It found that barberry increased arteries’ flexibility and reduced inflammation.

As the heart pumps blood, the arteries expand and contract to accommodate the changing volume of blood and maintain a steady blood pressure. When the blood pressure is too high, this increases the risk of heart attack and stroke. The lining of the arteries, or endothelium, plays an important role in maintaining healthy blood pressure by releasing signals which relax the arteries. When the lining does not work as well as normal, this is known as endothelial dysfunction (ED). ED is closely connected to high blood pressure, and also increases the risk of hardening of the arterial walls (arteriosclerosis). ED may be caused by inflammation within the arteries.

Barberry is an evergreen herb whose berries are used traditionally as both a flavoring and medicine. Barberry is rich in plant antioxidants known as polyphenols, which may reduce inflammation. One of these antioxidants is berberine, which is isolated and sold as a supplement. Barberry is traditionally used for high blood pressure. It has also been traditionally used for acne, to lower blood sugar, and for infection. Barberry’s effect on endothelial function and inflammation in patients with high blood pressure has not been well studied.

This study included 84 patients with hypertension. The average age was 54, and a third of the patients had diabetes. Half of the patients were randomly assigned to take barberry powder daily. The other half took a similar-looking inactive powder (placebo). The two groups had similar weights  All patients were followed for 8 weeks.

The researchers measured the flexibility of the arteries using flow-mediated dilation (FMD). This test uses a pressure cuff to restrict blood flow through the arm. Then, ultrasound is used to measure how well the arteries expand when the cuff is released. The two groups had similar FMD values at the beginning of the study. After 8 weeks, the patients taking barberry had significantly better FMD (6.54% increase).

The researchers measured markers of inflammation within the blood vessels. These included MCP-1, a small signal molecule which attracts white blood cells. These markers of inflammation were significantly reduced for patients taking barberry.

Two patients taking barberry experienced diarrhea. There were no serious side effects.

This study found that barberry supplements improved inflammation and flexibility of blood vessels for patients with hypertension.

FMD is a subjective test and can vary between who measures it. However, the operator did not know whether a patient was taking barberry or placebo. Also, this short study did not test barberry’s effect on blood pressure.

Talk to your health care provider before using barberry. Barberry may cause birth defects, and also interacts with some medications.