Lignans are specific types of compounds that are commonly found within sunflower seeds, peanuts, strawberries and flaxseeds, and their great benefit to our health is related to breast cancer. Breast cancer is often worsened by high estrogen levels in the body, because certain tumors are estrogen-dependent. Lignans are able to stop the flow of estrogen to these tumors, causing them to shrink and disappear, in a perfect world. Adding these lignan-rich foods to your diet is a very good choice if you are at a high risk of breast cancer or if you have already been diagnosed.