from "Fats that Heal, Fats that Kill" by Udo Erasmus...
"While flax oil is useful for treating degenerative diseases, it is too w3 rich(about 4 times as much w3 as w6)to be used exclusively in the long term. One can develop a w6 deficiency by using ONLY flax oil for too long. While it took me about 2 years to end up with thin, papery feeling skin that dried out and cracked easily, w6 deficiency could develop in as short as 10 or 16 mos. of EXCLUSIVE use of flax oil."