Flaxseed is one of only a few foods that contain the essential fatty acid alpha-linolenic acid. The "essential" means that you have to eat this particular nutrient to get it, because your body can't make it. Once it's in your digestive system, alpha-linolenic acid converts to a type of omega-3 fatty acid and works to prevent blood clot formation. Quite simply, adding ground flaxseed to your diet cuts your risk of having a fatal heart attack.
In addition to protecting your heart, flaxseed and flaxseed oil keep cell membranes healthy and act as an anti-inflammatory to ease the pain and swelling of arthritic joints. The seed is a good source of fiber, too.