I noticed there was a question on the PRAL of different foods beyond the list I included at http://www.t-mag.com/nation_articles/269cov.jsp.
Well, for starters, Tampa Terry posted a fantastic resource on acid-base status ... http://www.acid-base.de/tabelle.htm
However, there are a few general "rules" so that if it isn't on the list you can make a good guess:
1) Within categories (meat, breads, etc), PRAL values are similar. So although Tuna isnt on the list, all the other proteins are acid-producing so it's safe to say Tuna will be too.
2) The Protein to Potassium ratio is the best predictor of PRAL. The higher this ratio, the more acid produced. (Although there is no "absolute" value system this way, you can look up the protein:potassium ratio of some reference food and then compare tuna to that to see if it's more acidic or basic). While this method isn't perfect, the Protein to Potassium ratio explains >80% of the variance of PRAL. Not bad!
3) WARNING - SEMINAR PLUG...This info on acid base status will be covered in my seminar in NYC on June 12th. The price is definately right so come check it out. For more info, drop a note to Mike at email@example.com or call 516-767-1718.