Omega-6 fatty acids are lipids that can be found in soybean oil, safflower oil, sunflower oil, and other liquid vegetable oils. Omega-3 fatty acids are lipids that can be found in walnuts, flaxseed, soybean oil, canola oil, shellfish, salmon, herring, sardines, anchovies, and trout. Steroids. Cholesterol is the most common type of steroid lipid. read more