Letter: Essential fatty acids in cystic fibrosis.

In three literature reports the linoleic acid (L.A.) levels for cystic fibrosis 
(C.F.) compared to controls are always more significantly lower than arachidonic 
acid (A.A.). Similarly the percentage lowering is also more for L.A. 
than A.A. There is, thus, no "overwhelming" evidence for a blocked 
or absent desaturase and the cause of the E.F.A. deficiency must 
be elsewhere. We have found up to 2.5% of the total 
fatty acids in both serum and red cells to be C20:3-omega-9. 
All of our C.F. patients have shown this acid at some 
stage and, for most, it is a permanent feature of their 
fatty acid profile. It has been reported that C20:3-omega-9 would probably 
act as an inhibitor of prostaglandin formation from A.A. and it 
is interesting to conjecture on whether this could account for some 
of the symptoms of C.F. C20:3-omega-9 would also be incorporated into 
P.I. and could then alter membrane properties. 