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Fat

You often hear that we need to eliminate as much fat as possible from our diet. Yet fat plays a number of important roles in the body. For example, fat is a good energy source (twice the calories of protein and carbohydrates). It also transports vitamins A, D, E, and K, which are fat soluble and need fat to be carried throughout the body. Fat provides essential fatty acids that the body cannot produce on its own and that must come from dietary sources. These essential fatty acids (omega-3 and omega-6) are needed for a healthy heart, hormone and cell production, and healthy skin. Body fat protects organs and acts as an insulator.

Even though fat plays many beneficial roles in the body, too much fat in the diet can lead to several diseases, including cardiovascular disease. As a result, we need to be careful about the amount of fat in our diet and ensure that we eat “good” fats. Obviously, fat must not be eliminated from our diets. Instead, we need to eat it in moderation and make a habit of making better choices.

The Three Kinds of Fat

There are three kinds of dietary fat :

  • Visible fat, which you can remove yourself (such as fat on meat or poultry skin)
  • Fat you add yourself to food (such as butter on toast or vegetables, dressing on salad, etc.)
  • Invisible fat, which occurs naturally (nuts, eggs, meat, etc.) or is added when food is made (muffins, chips, fried foods, etc.). It cannot be removed once added. This is often the kind of fat that goes unnoticed in what we eat.

Practical Advice

The following recommendations can help you reduce your fat intake.

  • Determine what contributes most of the fat in your diet.
  • Reduce serving size and how often you eat high-fat foods.
  • Choose lower-fat dairy products and lean cuts of meat.
  • Reduce the amount of oil or fat in your recipes.
  • Choose foods with fat that is less harmful to cardiovascular health. Harmful fats includes saturated fats (found in many animal and commercial products) and trans fat (found especially in commercial products containing hydrogenated fat or shortening.
  • For cooking, dressing, and recipes, opt for monounsaturated or polyunsaturated fats For example, cook with canola or olive oil, instead of butter or vegetable shortening.
  • Whenever you spread cheese, peanut butter, or jam on bread, leave out the butter or margarine.
  • Opt for nonsitck pans to reduce fat use for cooking.

According to the 2002 DRIs, the recommended daily total fat intake is 20% to 35% of your total calorie intake. To illustrate, a 30% intake of fat is about :

  • 65 g of fat per day for women 19 to 49 years of age
  • 90 g of fat per day for men 19 to 49 years of age

The Different Types of Fat

Saturated Fats

Saturated fats are found in many animal products such as meat, poultry, eggs, butter, and dairy products (e.g. cheese, milk, and yogurt), and various commercial products, such as pastries, croissants, cookies, and crackers. They are harmful for your heart. Saturated fats can lead to atherosclerosis (build up of fat in arteries); high-fat diets can therefore increase the risk of cardiovascular disease.

Trans Fat

Trans fats are found particularly in commercial products containing hydrogenated fat or shortening, such as pastries, commercial muffins, and hard margarine. Trans fats are produced by a process called hydrogenation that alters the chemical configuration of liquid fats to make them solid. Trans fats are just as harmful to health as saturated fats because they increase the risk of cardiovascular disease. Try to eat food that has been less processed whenever possible, such as homemade muffins (with vegetable oil) or homemade banana or cranberry bread. You can also choose the type of fat that you eat!

Unsaturated Fats

Unsaturated fats include polyunsaturated fats and monounsaturated fats. Studies tend to show that eating these two types of fat lowers serum cholesterol when they replace saturated fats.

Monounsaturated Fats

Olive oil, canola oil, avocados, and nuts (pistachios, almonds) contain significant amounts of monounsaturated fats.

Polyunsaturated Fats

Polyunsaturated fats are found especially in vegetable oils (such as sunflower, safflower, soy, and corn oil) as well as in various nuts and seeds (English walnuts, sunflower seeds).

Omega-3 Fatty Acids

In recent years, nutritional science has revealed that certain fish are high in omega-3 fatty acids. Omega-3 fatty acids are a type of polyunsaturated fatty acid. Since the body cannot produce them and they are essential, we must get them from dietary sources. A deficiency in essential fatty acids increases the risk of bacterial infection and inflammation.

Virtues of Omega-3 Fatty Acids

Epidemiological studies during the seventies revealed that the Inuit of Greenland had a much lower incidence of heart disease than several other populations. The reason was the omega-3 fatty acids in the fish they ate as part of their diet. Since then, some 4500 studies have been conducted to assess how omega-3 fatty acids and fish oil affect the health of individuals.

Investigators consider that omega-3 fatty acids can help lower triglyceride levels and reduce the risk of sudden death due to heart-related causes. Some data show that oil containing omega-3 can help lower the incidence of coronary heart disease in individuals at risk. Omega-3 fatty acids act on blood platelets somewhat like aspirin by reducing clot formation. They can also reduce arrhythmia in some people with heart disease.

Omega-3 fatty acids are deposited in nerve tissue that is high in lipids, such as the brain and retina, during the last trimester of pregnancy and the first year of life. Health Canada recommends pregnant and nursing women increase their intake of omega-3 fatty acids.

Dietary Sources

The 2002 dietary reference intakes has established the adequate intake of omega-3 fatty acids to be 0.6% to 1.2% of energy, which is 1300 to 2500 mg a day on the basis of a 2000-calorie diet.

Omega-3 Content of Some Foods
Food Serving Omega-3 (mg)
Salmon, pink, canned 100 g 1300
Canola oil* 15 mL (1 tbs.) 1300
Flaxseed oil* 5 mL (1 tsp.) 3250
Flaxseed, ground 15 mL (1 tbs.) 1950
English walnuts or pumpkin seeds 15 mL (1 tbs.) 430
Sardines 100 g 500
Tuna, light, canned 100 g 650

* Oil must not be heated in order to preserve the content of omega-3 fatty acids.

Eat fish two or three times a week to get the benefits of oils like omega-3. Avoid fried or breaded fish: opt instead for baked.

Fish Choices

Not all fish contain the same levels of omega-3 fatty acids.

  • High levels : salmon, tuna, sardines, mackerel, lake trout, and anchovies.
  • Moderate levels : rainbow trout, halibut, largemouth bass, and shark.
  • Low levels : turbot, cod.