Interesting paper in the latest AJCN:

Petra LL Goyens, Mary E Spilker, Peter L Zock, Martijn B Katan, and Ronald P
Mensink 
Conversion of alpha-linolenic acid in humans is influenced by the absolute
amounts of alpha-linolenic acid and linoleic acid in the diet and not by their
ratio 

Am J Clin Nutr 2006 84: 44-53

Abstract at:
http://www.ajcn.org/cgi/content/abstract/84/1/44

(I did not copy/paste the abstract in this case, as the number of special
characters in the text, makes tedious hand-correction necessary.)

Tom Billings