A lipid is a fat-like molecule and is a major building block of the cells of animals. Lipids are organic, meaning that they contain carbon atoms. Lipids do not dissolve in water. There are several types of lipids.
Examples of Types of Lipids
Fats make up the largest category of lipids, and also go by the terms triacylglycerols, triglycerides, and glycerolipids. There are several types of fats.
- Saturated fat is a lipid that exists as a solid substance when it is at room temperature. Milk, cheese, meat, and other animal foods contain saturated fat. Palm oil, cocoa butter, coconut oil, and other tropical oils also contain saturated fats, and these types of oils can be found in snacks, whipped toppings, and coffee creamers. Butter, margarine, and shortening also contain a great deal of saturated fat.
- Unsaturated fat is a lipid that exists as a liquid when it is at room temperature. Oils from plants contain unsaturated fat. There are two types of unsaturated fats:
- Monounsaturated fat is found in olive, peanut, canola, and other vegetable oils.
- Trans fat is a lipid that has undergone a process called hydrogenation. Hydrogenation causes the fat to harden more, which can then be used to make crispy foods such as potato chips, crackers, and cookies, as well as some types of salad dressings, margarines, and other processed foods.
- Polyunsaturated fat is also found in vegetable oils, but in different ones, including sunflower, sesame, corn, soybean, and safflower oil. Seafood also contains polyunsaturated fat.
There are two types of polyunsaturated fats:
- 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.
- Cholesterol is the most common type of steroid lipid.
- Estrogen, the “female hormone,” is a lipid.
- Testosterone, the “male hormone,” is a lipid.
- Bile salts are lipids that are found in human intestinal bile.
- Cortisol is a lipid hormone that is produced in response to stress.
- The wax made by bees is classified as a lipid.
- Human ears make wax, and this wax protects the inside of our ears.
- A substance called cutin is found on the surfaces of plant leaves. This wax stops water from evaporating from the leaves, and protects and seals the plant.
Fat-soluble vitamins are lipids:
- Vitamin A is important to immune function, vision, and reproduction, and is found in colorful fruits and vegetables, as well as in whole milk and liver.
- Vitamin D is used to enhance how people’s intestines absorb calcium, zinc, phosphate, iron, and magnesium. It is obtained from certain foods and by exposure to sunlight.
- Vitamin E protects the human heart and helps protect the body from free radicals, therefore helping to keep our cells healthy. It is found in nuts, seeds, and vegetable oils.
- Vitamin K allows our blood to clot, and may aid with bone strength in elderly people. It can be found in kale, spinach, turnip greens, collards, Swiss chard, mustard greens, parsley, romaine, green leaf lettuce, Brussels sprouts, broccoli, cauliflower, cabbage, and fish, liver, meat, eggs, and cereals.
These examples of lipids show that they are contained in different categories and are very common in everyday life.