  urlLink DrWeil.com Question: Flaxseed for Kids? : "Sprinkle a tablespoon or two of the ground seeds on cereal or add them to salads, or mix them with your child’s peanut butter. A teaspoon of ground flax should be enough for a toddler. Ground flaxseed provides alpha-linolenic acid (ALA), which the body converts to the same heart-protective omega-3 fatty acids found in salmon, sardines and other oily fish.
They also provide fiber and are one of the richest dietary sources of lignans, a class of phytoestrogens thought to help protect against breast, prostate and colon cancers. However, flaxseed isn’t as good a source of omega-3s as fish oil, which contains the pre-formed omega-3 s that the body needs. You should be able to find a pleasant tasting fish oil for children. Nordic Naturals makes several that appeal to kids. You can start giving children supplements after they begin eating solid food. " 
