Flaxseed, as an antioxidant believed to prevent and protect against cancer, contains alpha linolenic acid, which is an omega-3 fatty acid, and lignan, a phytoestrogen which appears to inhibit estrogen production -- a benefit for women with estrogen-positive breast cancers. For maximum nutritional value, buy whole flaxseed, and measure out the amount the seeds desired for each recipe, grinding the flaxseed in a small coffee bean grinder. Grinding breaks down the outer shell and releases the beneficial oil. Store whole flaxseed in a dry sealed container. Ground flaxseed needs to be refrigerated in an airtight container, and is good for about a month. Flaxseed oil is available, usually in the cooler section of the store, and you can purchase flaxseed oil supplements. To incorporate flaxseed into your daily diet, simply sprinkle fresh ground flaxseed on your breakfast cereal, on lunch or dinner salads, in baking goods, or as a topping for yogurt. The more you use flaxseed, the more uses you will find for it. You can substitute flaxseed oil for other oils when making salad dressings or as a butter substitute on steamed vegetables. Research is continuing to indicate that flaxseed might be a beneficial cancer prevention food for a number of cancers, including breast cancer, prostate cancer and melanoma.