Scott I believe you are referring to this:
Flax provides a form of n-3 fatty acid that is 18 carbons long and out body needs varieties that are 22-24 carbons long. Our enzyme systems are very inefficient at this process so even if one takes a lot of flax oil it does not make much EPA or DHA (the stuff in fish oil and the fatty acids we WANT).
Part of why we want n-3 fatty acids if for the anti-inflammatory effects...well, supplementing with flax oil actually increases the amounts of inflammatory cytokines that we are trying to suppress! One step forward, two steps back. Flax oil will prevent a vegan form keeling over from fatty acid deficiency but it will not optimize performance, health or longevity.
I was able to find a few studies that actually contradict what Robb said, and one that support it. Not saying he's full of it, maybe he can reference a study if he reads this. but here's what I found:
Summary: Basically, flax oil supplementation slightly decreased the AA/EPA ratio as the fish oil greatly decreased the AA/EPA ratio. So flax oil actually helped somewhat, but not nearly as well as fish oil.
Summary: Flax oil supplementation created improvements in arterial function despite a rise in LDL oxidation.
Summary: Fish oil supplementation produced improvements in both small, dense LDL and EPA & DHA levels. Flax produced none.
These studies say nothing about cytokine levels, but they do directly measure cardiovascular improvements, and that's the main issue after all. I'm finding that both flax and fish oils reduce inflammation, just that fish oil is better at it. Maybe Robb could chime in and set it straight.