A Primer on Fats and Oils

Fat Facts

Fats occur naturally in food and play an important role in nutrition. Fats and oils provide a concentrated source of energy for the body. Fats are used to store energy in the body, insulate body tissues, and transport fat soluble vitamins through the blood. They also play in important role in food preparation by enhancing food flavor, adding mouth-feel, making baked products tender, and conducting heat during cooking.

Not All Fats and Oils Are Created Equally

Fats and oils are made up of basic units called fatty acids. Each type of fat or oil is a mixture of different fatty acids.

  • Saturated Fatty Acids are found chiefly in animal sources such as meat and poultry, whole or reduced-fat milk, and butter. Some vegetable oils like coconut, palm kernel oil, and palm oil are saturated. Saturated fats are usually solid at room temperature.
  • Monounsaturated Fatty Acids are found mainly in vegetable oils such as canola, olive, and peanut oils. They are liquid at room temperature.
  • Polyunsaturated Fatty Acids are found mainly in vegetable oils such as safflower, sunflower, corn, flaxseed, and canola oils. Polyunsaturated fats are also the main fats found in seafood. They are liquid or soft at room temperature. Specific polyunsaturated fatty acids, such as linoleic acid and alpha-linolenic acid, are called essential fatty acids. They are necessary for cell structure and making hormones. Essential fatty acids must be obtained from foods we choose.
  • Trans Fatty Acids are formed when vegetable oils are processed into margarine or shortening. Sources of trans fats in the diet include snack foods and baked goods made with "partially hydrogenated vegetable oil" or "vegetable shortening." Trans fatty acids also occur naturally in some animal products such as dairy products.

Cholesterol is Different

Blood (serum) cholesterol and dietary cholesterol are two different types of cholesterol. Dietary cholesterol is found in food of animal origin such as egg yolks, organ meats, and full fat dairy products. Blood cholesterol is a waxy substance, which occurs naturally in our body. It is used to make estrogen and testosterone, and bile, which is needed for digestion. But if the level of cholesterol in the blood is too high, cholesterol and other fats can stick to the artery walls.

Since blood cholesterol is waxy and cannot dissolve in water, it is carried through the blood in packages called lipoproteins. High density lipoprotein (HDL) is a "good" package for cholesterol and low density lipoprotein (LDL) is a "bad" package for cholesterol.

HDL cholesterol gathers up excess cholesterol in the blood and carries it to the liver. The liver reprocesses or excretes it. HDL may also help remove some of the cholesterol deposited on the artery walls.

Excess LDL cholesterol can increase the risk of heart disease because it is LDL cholesterol that builds up on the artery walls. The type of fats and oils we eat helps control LDL levels.

Research Says.
  • Eating too many foods high in saturated fat may increase blood levels of LDL and total cholesterol. High blood levels of LDL and total cholesterol are risk factors for heart disease.
  • Eating foods high in monounsaturated fatty acids may help lower LDL cholesterol levels and decrease risk of heart disease.
  • Eating polyunsaturated fats in place of saturated fats decreases LDL cholesterol levels.
  • Trans fatty acids act like saturated fats and raise LDL cholesterol levels. They may also lower HDL cholesterol in the blood.
Fat and Cholesterol: Know Your Limits

The guidelines for fat intake are well known: for healthy Americans, consume no more than 30 percent of total calories from fat. The "30 percent" guideline means:

  • 7-10 percent of total calories from saturated fats,
  • About 10-15 percent of total calories from monounsaturated fats, and
  • About 10 percent from polyunsaturated fats.

For cholesterol, healthy Americans should limit their intake to less than 300 milligrams per day.

Knowing your limits includes eating healthfully - include 5 or more servings of fruits and vegetables each day. Base your meals on whole grains, beans, and legumes, or a 4-ounce portion of lean meat or poultry without the skin, and 2-3 servings of low-fat or fat-free dairy products each day. Limit your intake of sweets, and other high-fat foods - and choose the type of fats and oils you eat carefully.

 For more information

  • The American Dietetic Association/National Center for Nutrition and Dietetics.
    ADA's Consumer Nutrition Information Line (800/366-1655) provides recorded messages with timely, practical nutrition information as well as referrals to registered dietitians. Messages are available 24 hours daily with new topics each month.
  • For more canola oil information and recipes, visit Canola Info at www.canolainfo.org
This fact sheet is supported by a grant from Canola Info. Acceptance of this grant does not constitute an endorsement by ADA of any company's products or services.
© ADAF 2001. Reproduction of this fact sheet is permitted for educational purposes only. Reproduction for sales purposes is not authorized.