It could be the fact that flax is such a rich source of phytoestrogens that could also be worrying people. I hear people warning against soy all the time because it is a rich source of phytoestrogens. Yet, flax seed is 3 times richer in phytoestrogens than soy. What people need to realize though is that phytoestrogens are not dangerous, but rather beneficial. Due to their weak nature phytoestrogens actually lock up estrogen receptors blocking the action of stronger estrogens, including the body's own estrogens and xenoestrogens.