Trans fatty acids in hardened vegetable oils

Dear Editors Van To1 and collaborators state that ‘commercial hardening of vegetable oils leads to the formation of unsaturated fatty acids with double bonds in the tram instead of the natural cis configuration. The same process takes place in the rumen of cows and sheep...’ [l]. This thesis may be handy for the margarine industry, but it is nevertheless a distortion. Firstly, the process in the rumen results from biological evolution (natural), catalyzed by bacterial enzymes (natural), at body temperature (natural) and at pressures permissive within a living organism (natural) [2]. What goes on in the hydrogenation reactor is due to human technology (artificial), catalyzed by metallic surfaces (artificial), at temperatures around 15O-200°C (artificial) and a pressure of around 3 atm (artificial) [3]. Hence, the first process is, by any semantics, ‘natural’ and the second ‘artificial’. This, not surprisingly, leads to a structural difference, in this case the position of the double bond [4]. Is this important? So far, all who separated effects of tram vaccenic acid from those of elaidic found different effects. At the biochemical level, elaidic acid sometimes stimulates and some-