Influence of d-Amino Acids in Beer on Formation of Uric Acid

Excessive intake of beer could increase serum uric acid levels, leading to high risk of gout, which was previously attributed to high purine content in beer. Recent reports that purine-rich vegetables and bean products do not cause higher uric acid levels do not support this theory. Why excessive intake of beer could increase a high risk of gout has been unclear. Other factors affecting the accumulation of uric acid in the blood have been explored. Beer contains relatively high levels of d-amino acids due to the racemization of l-amino acids induced by food processing. d-amino acid was catalyzed by d-amino acid oxidase to produce H₂O₂, which is further oxidized in the presence of Fe²⁺ to produce hydroxyl radicals, resulting in DNA damage and formation of a large amount of purine bases, which are oxidized to uric acid by a series of enzymes. Some food ingredients, such as vitamins and I^-, prompt d-amino acids to form uric acid. d-amino acids in beer are one of the key factors responsible for the increase in uric acid levels. The biological response of d-amino acids could explain gout occurrence in beer drinkers.