I never heard of purine. (A white crystalline substance that is one of the building blocks of DNA. Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved) But it turns out that O blood types need it to live. I have O positive blood and I found out the hard way that I should have never given up eating meat. I cried the first time I cooked beef after 22 years of vegetarianism. I thought I was choosing the healthy option NOT eating meat. But what is healthy for one body can nearly be poison to another. Not one vegetarian book I'd ever seen had a warning mentioning this. O blood is most common. So many vegetarians are in the same boat I was in. Check your skin color, energy, and see someone like Aubrey Thompson at Living Balance Wellness, in Dedham MA, to find out what food works best for you to feel your best. Without purine, a person's whole immune system can go off the rails. Books like the, Metabolic Typing Diet, by William L. Wolcott and Trish Fahey and Eat Right For Your Blood Type, by Dr. Peter J. D'Adamo and Catherine Whitney, can help. I was losing muscle mass and withering away. I got super sick. Don't let this happen to you. Let us all thrive. Learn what foods are best for you, for real.