As I have alluded to a number of times over the years it is because flax seed oil does not help raise your levels of DHA which is probably the most important of all the essential fatty acids. Proponents of flax seed oil will tell you that the body can convert ALA (which is the main constituant of flax seed oil) to DHA.
This is simply not true…at least to any extent. A minute fraction may be able to be converted but nowhere near enough to meet your body’s needs. This is because the DHA molecule is a lot more complex that the ALA molecule. Please read more about Omega-3s.
A recent study concerning the issue of ‘conversion’ of these components of Omega 3 has just been completed. It provides more evidence of what we already know but many people/companies continue to deny. For more info please click here.
As an added footnote, it is also difficult to convert EPA to DHA for the same reasons. Also, note that is is easy for DHA to convert to EPA or ALA because it just has to drop off some components to convert which is a lot easier than trying to add components on.