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Dark chocolate may cut stroke damage to brain

Compound in dark chocolate might protect brain after ischaemic stroke

OnMedica staff

Thursday, 06 May 2010

A compound found naturally in dark chocolate may protect the brain from damage after a stroke, a US study in mice has found. Researchers from Johns Hopkins University School of Medicine report in the Journal of Cerebral Blood Flow and Metabolism that epicatechin seems to have a protective effect by increasing cellular signals already known to shield nerve cells from damage.

They first fed a group of mice a small amount of epicatechin, which occurs naturally in dark chocolate; a second group of mice had none of the compound. An ischaemic stroke was induced in both groups of mice 90 minutes later. The mice that had ingested the epicatechin suffered significantly less brain damage than the mice that had not been given the compound.

Epicatechin was also effective in limiting further neuronal damage in the mice when given 3.5 hours after an ischaemic stroke. If it was given 6 hours after the stroke, the compound gave no effective protection. This contrasts with most currently used stroke drugs, which are only effective when given within two to three hours of a stroke.

The researchers says that their study appears to show that epicatechin activates two well-established pathways known to shield the brain from damage. Mice that selectively lacked activity in those pathways had no protective effect from epicatechin – their brain cells died after a stroke.

The authors say they have not studied the amount of chocolate that would be need to be eaten to benefit from epicatechin’s protective effect, but the current research suggests that it could be quite small because the suspected beneficial mechanism is indirect: “Epicatechin itself may not be shielding brain cells from free radical damage directly, but instead, epicatechin, and its metabolites, may be prompting the cells to defend themselves.”

But they warn that some dark chocolates have more bioactive epicatechin than others: “The epicatechin found in dark chocolate is extremely sensitive to changes in heat and light. In the process of making chocolate, you have to make sure you don’t destroy it. Only few chocolates have the active ingredient. The fact that it says ‘dark chocolate’ is not sufficient.”

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