A Spokesman for Brewing Research International said that they believe that "'antioxidant compounds' in the Guinness, similar to those found in certain fruits and vegetables, are responsible for the health benefits because they slow down the deposit of harmful cholesterol on the artery walls." The same benefits are not gained by drinking lager.
However, spokesmen for Diageo, the company that manufactures Guinness, was quick to add "We never make any medical claims for our drinks."
