The facts on fat are an evolving story. Recently the American Heart Association increased their recommendations for daily fat intake up to 35% of total calories, from 30% for some individuals.
The evidence is clear that to treat or prevent coronary heart disease, a diet should be rich in the right kinds of fats and low in the wrong kinds of fats.
Reduce saturated fat, and strive to eliminate unnaturally occurring trans fats. Use the following information to increase your knowledge of the fat facts.
Fats and oils are made of mixtures of fatty acids. Each fat or oil is called "saturated," "monounsaturated" or "polyunsaturated," depending on the most common type of fatty acid it contains.
Omega-3 Polyunsaturated Fat
Polyunsaturated fatty acids have at least two places that hydrogen can be added to the molecule. Polyunsaturated fats are liquid both at room temperature and in the refrigerator. There are two kinds of polyunsaturated fatty acids: Omega-3 and Omega-6.
Chemical Facts
- Omega-3's are one type of polyunsaturated fat. Polyunsaturated means that the molecules have many places where they are not saturated with hydrogen.
- These molecules have bends in the places where they are unsaturated. Because of these bends, the fat molecules are subject to attack by oxygen, which allows them to become rancid easily.
- Also because of the many bends, they are liquid at room temperature. Omega-3's are especially abundant in deep-sea fish-they serve as a form of "antifreeze" for the fish.
- The human body cannot manufacture Omega-3's, so they are essential in the diet.
- The most common Omega-3 fatty acids from fish are called EPA (20:5), and DHA (22:6).
- The most common Omega-3 fatty acid from plants is called linolenic acid (18:3).
Health Facts
- Omega-3 fatty acids make the blood less prone to forming clots and the blood vessels less prone to forming plaques. This is why eating more Omega-3's lead to a reduction in heart attacks.
- Omega-3 fatty acids protect the heart from irregular rhythms and, therefore, lead to a reduction in sudden cardiac death. In the same way that Omega-3's stabilize the cell membranes in the cells of the heart, there is some limited evidence that Omega-3's may help to stabilize the cell membranes in brain cells leading to a reduction in depression. Look for more research in this area.
- Omega-3's lower total cholesterol, triglycerides & increase HDL "good" cholesterol. The effect on LDL "bad" cholesterol is still a matter of debate.
Dietary Sources
- Deep-sea cold-water fish such as salmon, tuna, mackerel, herring, bluefish, and sardines.
- A less potent plant type of Omega-3 is found in walnut, purslane and flaxseeds as well as the oils made from those nuts and seeds.
Dietary Action Items
- Include at least two servings of fatty fish in your diet each week.
- Eat deep-sea cold-water fish that are rich in the healthy Omega-3 fatty acids such as salmon, tuna, mackerel, herring, bluefish and sardines.
- Make your fish meal especially healthy by cooking fish without adding unhealthy fats; grill, bake or broil your fish. Avoid cream or other fatty sauces and do not bread fish.
- An FDA advisory warns that pregnant women and women of childbearing age who may become pregnant not eat shark, swordfish, king mackerel, and tilefish.
- Include plant-based sources of Omega-3's in your diet
- Add flaxseeds to your morning cereal.
- Snack on walnuts or almonds -- but beware of extra calories.
- Use purslane, a leafy green vegetable, in your salads.
Monounsaturated Fat
Monounsaturated fatty acids have only one place that hydrogen can be added to the molecule. Monounsaturated oils are liquid at room temperature but start to become solid at refrigerator temperatures.
Chemical Facts
- Monounsaturated fatty acids have only one place that hydrogen can be added to the molecule.
- These molecules have a single bends in the place where they are unsaturated. Because of this single bend, they are less subject to attack by oxygen than polyunsaturated fats, but more subject to attack than saturated fat. This means that they are less stable than saturated fats, but more stable than polyunsaturated fats.
- Also because of this single bend, monounsaturated fats are liquid at room temperature but start to become solid at refrigerator temperature.
Health Facts
- Decreases triglycerides and increases HDL ("good") cholesterol -- both considered good things. May lower total cholesterol. The best health effects are achieved when monounsaturated fats replace saturated fats.
- Like all fats, monounsaturated fats contain a great deal of calories. If simply added to the diet, instead of replacing other less healthy foods, monounsaturated fats will cause weight gain.
Dietary Sources
- High fat vegetables such as olives and avocados.
- Nuts and seeds (almonds, cashews, peanuts, pecans and sesame seeds).
Dietary Action Items
- Make mono's the primary source of fat in your diet
- Use olive oil, canola oil or peanut oil when cooking.
- Sprinkle sliced almonds, olives or avocado on salads.
- Make your own salad dressing using olive or canola oil.
- Don't just add good fats to a bad diet. Get rid of unhealthy saturated and trans fats -- eat monounsaturated fat instead.
- Dip bread in olive oil instead of using butter or margarine.
- Eat a small handful of nuts instead of snacking on chips or other greasy snacks.
- Spread natural peanut butter, almond butter, or hummus on a bagel in place of butter or cream cheese.
Omega-6 Polyunsaturated Fat
Polyunsaturated fatty acids have at least two places that hydrogen can be added to the molecule. Polyunsaturated fats are liquid both at room temperature and in the refrigerator. There are two kinds of polyunsaturated fatty acids: Omega-3 and Omega-6.
Chemical Facts
- Omega-6's are one type of Polyunsaturated Fat. Polyunsaturated means that the molecules have many places where they are not saturated with hydrogen.
- These molecules have bends in the places where they are unsaturated. Because of these bends, the fat molecules are subject to attack by oxygen, which allows them to become rancid easily.
- Also because of the many bends, they are liquid at room temperature.
- The human body cannot manufacture Omega-6's, so it is essential that Omega-6's are included in the diet.
- The most common Omega-6's are linoleic (18:2) and arachidonic (20:4)
Health Facts
- The good news is that Omega-6's have been shown to reduce the LDL "bad" cholesterol, but the bad news is that they may also reduce HDL "good" cholesterol.
- The optimal ratio of Omega-3 to Omega-6 remains unknown and is the subject of a great deal of research.
- Only small amounts of Omega-6's are required; if this requirement is not met deficiency symptoms arise. In the western diet it is extremely difficult to have an Omega-6 deficiency since there are some Omega-6's in almost all fat containing foods.
- In general, Omega-6's are considered a better choice than saturated (animal) or trans fats (hydrogenated), but are probably not as healthy as Omega-3 or monounsaturated oils.
Dietary Sources
- Abundant in the standard American diet
- Found in plant oils such as Corn, Safflower & Soybean oil. Omega-6's are the primary type of fat in commercial oil-based salad dressings.
- The Omega-6’s can be identified as those fatty acids with names containing “n-6” as well as linoleic acid, which is identified as “18:2”.
Dietary Action Items
- Do not make the Omega-6's your primary source of dietary fat.
- Limit, but do not eliminate, the amount of Omega-6 in your diet by choosing olive, canola and peanut oils instead of corn, safflower, and soybean Oils.
Saturated Fat
Saturated fatty acids have all the hydrogen the carbon atoms can hold; they are saturated with hydrogen. Chemically stable, saturated fats are usually solid at room temperature, they don't combine readily with oxygen and turn rancid.
Chemical Facts
- Saturated fatty acids have all the hydrogen the carbon atoms can hold -- they are saturated with hydrogen.
- Since they are saturated with hydrogen, they are not vulnerable to attack by oxygen are therefore are chemically stable.
- Saturated fats are long straight molecules. This shape causes them to usually be solid at room temperature.
Health Facts
- The most important change a person can make to reduce LDL-cholesterol is to reduce the amount of saturated fat they eat.
- Saturated fats raise blood cholesterol, and the risk of coronary heart disease rises as blood cholesterol levels increase.
- Reducing saturated fat may reduce the risk of diabetes.
Dietary Sources
- Saturated fats come from animal sources such as whole milk, cream, ice cream, whole-milk cheeses, butter, lard and meats.
- Saturated fats are also found in tropical plant oils such as palm, palm kernel and coconut oils, and cocoa butter.
Dietary Action Items
- Limit the amount of saturated fat in your diet.
- If you eat meat, choose small portions of lean meats such as white meat chicken or turkey, lean ham, seafood, or lean beef, and always trim off all visible fat.
- Treat yourself to a healthy vegetarian dinner at least once a week. Eat a meal that is not just free of meat, but is also excludes french fries and other fried foods, does not contain cream soup or other full fat dairy, and that does not other include sugary or greasy foods.
- Choose 1% or non-fat dairy products (but beware of high sugar content in low-fat yogurt and ice cream).
- Read food labels & make choices that are low in saturated fats (less than 3 grams of saturated fat per serving). A person with heart disease on a 2000 calorie diet should not eat more than 15 1⁄2 grams of saturated fat each day.
- Avoid fried foods and fast foods
- Replace saturated fats with unsaturated fats.
- Use olive oil instead of butter for flavor.
- Cook with canola, olive or peanut oil instead of butter or lard.
- Eat fish instead of meat.
- Use salad dressings based on canola, olive or peanut oil instead of creamy dressings such as ranch or blue cheese.
Trans Fat
Trans fatty acids are created in laboratories by saturating oils with hydrogen. As a result, they are more solid and less prone to spoilage.
Chemical Facts
- Trans fats are most often not naturally occurring fats. Scientists have developed a chemical technique called hydrogenation that changes liquid vegetable oils into a more solid form. At the time of its creation, this was believed to be a great scientific advance, because the fat did not turn rancid as quickly. Recent evidence tells us that the invention of trans fats would be better described as a scientific setback.
- Trans fatty acids are produced commercially by heating vegetable oils in the presence of a metal catalyst and hydrogen.
- Trans fats are chemically stable, so they don't combine readily with oxygen and turn rancid.
- Trans fats are solid at room temperature.
Health Facts
- Trans fats decrease HDL ("good") cholesterol -- something that increases the risk of heart disease.
- Trans fats increase total and LDL ("bad") cholesterol. Trans fats also increase triglycerides.
- High intake of trans fats is a strong predictor of increased heart disease.
- Trans fats have recently been found to be closely associated with an increased risk of diabetes.
Dietary Sources
- Trans fats are widely present in common food products such as margarine, as well as in commercially baked goods such as breads, cakes and pastries. Trans fats are common ingredients in many processed foods, prepared meals, chips and fast foods.
- French fries, donuts and other commercial fried foods are major sources of trans fat in the diet.
- Current nutrition labeling regulations in the US do not require that the amount of trans fat be listed; however this is expected to change.
Dietary Action Items
- Avoid trans fats.
- Check food labels for the words "hydrogenated" and "partially hydrogenated" oil and avoid those foods.
- Limit or avoid fast foods and fried foods. If you do eat fried foods use olive, canola or peanut oil and do not reuse oil.
- Avoid commercially baked goods unless you can determine that they have not been prepared with hydrogenated oils.
- If you eat margarine, choose soft margarine instead of stick.