Does flax seed inhibit aromatase (estrogen) or does it increase testosterone?

No. Flaxseed is sometimes tried for cancer because it is broken down by the body into chemicals called “lignans.” lignans are similar to the female hormone estrogen - so similar, in fact, that they compete with estrogen for a part in certain chemical reactions. As a result, natural Estrogens seem to become less powerful in the body. Aromatase is not estrogen.