Alpha-linolenic acid. Computer model of a molecule of alpha-linolenic acid (ALA), an omega-3 essential fatty acid. Atoms are represented as spheres and are colour-coded: carbon (blue), hydrogen (gold) and oxygen (red). This is a polyunsaturated fat. ALA is found in plant oils, especially flaxseed oil. Omega-3 fatty acids have anti-inflammatory properties and may help to prevent heart disease and arthritis.