Umami: The Taste That Drives Purine Intake

Rheumatologists commonly recommend low purine diets to gouty subjects based on studies linking the purine contents of food to increased risk for gout1. However, most rheumatologists, as well as physicians in general, do not know that one of the basic 5 human tastes is for purine-rich foods, a taste known as umami (oo-mah-mee). We present evidence of this revelation and why this may have occurred. Historically, an elevation in serum urate was considered benign except for carrying an increased risk for gout. Recently, soluble urate has been found to have myriad biologic effects, including raising blood pressure, increasing hepatic fat stores, and inducing insulin resistance2,3. Indeed, the uricase mutation that occurred in the mid-Miocene likely provided a survival advantage to our ancestors during a period of famine that occurred during that time in Europe4. If uric acid has an important role in human survival, then it is logical that there should be a taste receptor that would encourage the ingestion of foods that raise serum urate. In addition to the classic tastes of sour, bitter, sweet, and salt, there is a fifth basic taste, umami. Umami is the “savory” flavor and was first identified in traditional Japanese foods such as kombu (sea kelp), where it was found to result from the presence of free glutamate. The umami receptor in the taste buds is complex, and consists of the metabotropic glutamate receptor-4, the G-protein-coupled heterodimer of taste receptor type 1 member 1 (TAS1R1), and taste receptor type 1 receptor3 … Address correspondence to Dr. R.J. Johnson, Division of Kidney Diseases and Hypertension, University of Colorado Denver, Aurora, Colorado 80045, USA. E-mail: richard.johnson{at}ucdenver.edu