 Flax has the highest content of lignans of all plant foods used for human consumption. The reason lignans is in quotes is because flax doesn't actually contain any lignans. Just like broccoli doesn't actually contain sephoraphane, flax does contain lignan precursors, though, which the good bacteria in our gut turn into lignans, which we can then absorb. So lignans are more of a team effort. We used to think our colon was just some transit tube that absorbed excess water. Now we know it houses what could be considered an entirely separate organ inside the body. Our gut flora are trillions of good bacteria, the densest concentration of microbes found anywhere on Earth. Exceeding the metabolic capacity of our liver, by a factor of 100, our good bacteria detoxify some compounds and activate others, boosting their bioavailability. In fact, that may be why urinary tract infections have been associated with breast cancer risk. The rounds of antibiotics may be wiping out some of the good bacteria that are helping us take advantage of all the wonders of a plant-based diet. I think most people only tend to think of our gut bacteria when there's a problem, but having good gut flora is more than just avoiding diarrhea. It's about maximizing our absorption of phytonutrients in our diet.