FlaxseedsNutty-flavored seeds that provide the most nutrition when ground.
Some studies suggest that flaxseed may help prevent everything from heart disease to cancers (like breast and ovarian) that are sensitive to hormones; and a 2010 study in The Journal of Nutrition suggests that it may even help reduce belly fat. Two of flax's secret weapons: omega-3s and phytoestrogens called lignans (flax has more of these plant compounds than any other food).
For a nutritious breakfast smoothie, blend 1 Tbsp. ground flaxseed, 1 Tbsp. flax oil, 1 cup carrot juice, 1 banana, 1 Tbsp. avocado, 1 kale leaf with the stem removed, and ice.