No, we cannot make all the lipids we need. In fact, we need two types of fatty acids that we can’t make: linoleic acid, an omega-6 fatty acid, and linolenic acid, which is also known as an omega-3 fatty acid. These acids are used to maintain cell membranes and to build hormonelike messengers known as eicosanoids, or the twenty carbon fatty acids such as prostaglandins. Good sources of omega-3 and omega-6 lipids are nuts, grains, and both fats and oils from vegetables or fish.