So I forwarded to Loren Cordain the post by Oliva questioning canola oil. I
asked him for a response for the list. He replied:

Subject: RE: Canola Oil question
Date: Sun, 2 May 2004 10:08:20 -0600
From: "Cordain,Loren" <[log in to unmask]>

Message-ID: <[log in to unmask]>
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
Recently it has been shown that the de-odorization process used during
the manufacture of many vegetable oils produces a trans isomer of 18:3n3
(alpha linolenic acid) (1). This isomer varies from 18:1n9 trans (trans
elaidic acid) which is the chief trans fatty acid produced during the
hydrogenation of vegetable oils to produce margarine and shortening.
The biological effects of trans ALA isomers are not as well known as
18:1n9 trans, but they do produce undesirable changes in the lipid
profile (1). A naturally occurring trans fatty acid (18:1n11 trans or
trans vaccenic acid) is present in the meat, milk and cheese from all
ruminants. Little is known about it's biological effects, but generally
it seems to be benign.

The deodorization process of canola oil or, soybean oil doesn't always
yield trans isomers of ALA, and careful deodorization processing
prevents the formation of trans ALA (1,2). When purchasing canola oil,
choose brands with labels guaranteeing freedom from trans fatty acids.

1.      Vermunt SH, Beaufrere B, Riemersma RA, Sebedio JL, Chardigny JM,
Mensink RP, TransLinE Investigators a.  Dietary trans alpha-linolenic
acid from deodorised rapeseed oil and plasma lipids and lipoproteins in
healthy men: the TransLinE Study.  Br J Nutr. 2001 Mar;85(3):387-92.
2.      Henon G, Kemeny Z, Recseg K, Zwobada F, Kovari K.  Deodorization
of vegetable oils. Part I: Modeling the geometrical isomerization of
polyunsaturated fatty acids. Journal of the American Oil Chemists
Society 76, 73-81.