Well, for some evolutionary reason, humans, birds, reptiles and great apes lack a liver enzyme called uricase which breaks down and regulates uric acid, a normal waste product of the purines found in many foods, such as shellfish and organ meats. Brewers yeast and hops, essential ingredients of beer, are also high in purines.
Timothy E. Quan, staff physician at Eastern Connecticut Health Network (ECHN) and clinical assistant professor of medicine at Yale University, said that beer packs a "triple whammy" because of its purine-rich ingredients, the dehydration it causes and the way it decreases the kidneys' ability to get rid of uric acid.