Flax is a plant that is grown for both its seed and its fiber. The fiber is used to weave linen. The seed is used in food products such as breads and cereals, and for making flaxseed oil. The fat in flaxseed is unsaturated and heart healthy. It contains alpha-linolenic acid, which is a type of fatty acid that must be obtained for the body from the diet, and is also associated with heart health. You will often hear it referred to as an omega-3 fatty acid. Flaxseed itself (ground or whole) also contains lignans, which may have antioxidant actions and may help protect against certain cancers, though this is far from certain. Flaxseed and flaxseed oil should be consumed as part of foods, not in supplement form.