Knowing how much of which fats to include in our diet is becoming increasingly challenging. First we assumed that the healthiest diets had the fewest calories coming from fats. Then we learned that it's not just the amount of fat but the type of fat in our diet that makes a difference -- some fats are acutally good for us because they help lower the risk of certain diseases. Now there's growing concern about the health risks of trans fats found in so many processed and fast foods. Although food labelling rules have changed, in the past unhealthy trans fats were not included on food labels so we sometimes consumed them without knowing it.
What are fats
Fats in foods are broken down into a myriad of fatty acids, each with its own chemical structure of long chains of carbon molecules attached to hydrogen atoms. Fatty acids are essential for various bodily functions, including cell growth and maintenance, hormone production and transportation of fat-soluble vitamins (A, D, E and K) throughout the body. They also help support the immune system. Some fatty acids that are not used are stored in triglyceride molecules as fat, giving our bodies a vital source of energy.
When it comes to calories, all fats are created equal -- all have nine calories per gram. As well, all fats make food taste better and help make us feel full because they empty slowly from the stomach. But that's where the similarities end.
Saturated fats (so-called because the fatty acids are completely saturated with hydrogen atoms) are solid at room temperature. A diet high in saturated fats can raise your LDL-cholesterol (the "bad" cholesterol) level and your risk of heart disease. You should limit your intake of saturated fats to 10 per cent of your daily calories. Animal products, such as poultry, eggs and full-fat dairy products, contain saturated fats, as do tropical oils, such as coconut, palm and palm kernel oils.
Saturated fats stats
Canola oil = 7%
Flaxseed oil = 10%
Sunflower oil = 12%
Corn oil = 13%
Olive oil = 15%
Soybean oil = 15%
Peanut oil = 19%
Lard = 43%
Palm oil = 51%
Butterfat = 68%
Coconut oil = 91%
Trans fats are created when a vegetable oil undergoes hydrogenation, a chemical rpocess in which hydrogen is added at high temperatures to make the oil solid. The process is commonly used by the food processing industry to prolong the shelf life of packaged products. Like saturated fats, trans fats raise LDL, or "bad," cholesterol and lower HDL, or "good," cholesterol. The well-known Nurses' Health Study showed that a woman's risk of developing type 2 diabetes increased with a greater intake of trans fats. To avoid trans fats, stay clear of partially hydrogenated vegetable oils and margarines; packaged foods, such as crackers and cookies; snack foods, such as potato chips; commercially baked products; and restaurant french fries and other fast food menu items.
Page 1 of 3 - Read page two to learn about good fats!
Unsaturated fats (fats in which the fatty acids are not completely saturated with hydrogen atoms) are liquid at room temperature. These can be subcategorized as either monounsaturated or polyunsaturated, depending on which fatty acids are present in the greatest concentration.
Monounsaturated fats protect against heart disease by lowering LDL-cholesterol levels. These fats are typically part of a Mediterranean diet, which is rich in fruits, vegetables, beans and legumes, as well as olive oil and nuts, which are associated with lower rates of heart disease and cancer. Olive, canola and peanut oils are high in monounsaturated fats, as are avocados, some margarines and nuts, such as almonds and hazelnuts.
Omega-3 fatty acids: These include eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and the essential fatty acid called alpha-linolenic acid (ALA). They help prevent blood clotting and thus reduce the risk of stroke. They help lower harmful triglycerides, reduce heart rhythm abnormalities and possible protect against heart disease. There's also some evidence that omega-3 fatty acids have anti-inflammatory properties that may be helpful for people with rheumatoid arthritis and other inflammatory conditions, such as colitis. You can get EPA and DHA from oily cold-water fish, such as salmon, mackerel, herring and sardines. ALA is found in flaxseeds and flaxseed oil, canola oil, soybeans and soybean oil, walnuts and, in smaller amounts, dark green leafy vegetables.
Omega-6 fatty acids: These fats provide your body with linoleic acid, the second essential fatty acid. They help lower LDL cholesterol but should be eaten in moderation since there's some evidence that large amounts can lower your HDL (or "good) cholesterol as well. You'll get omega-6 fats from eating safflower, sunflower, corn, soybean and sesame oils, as well as almonds, pecans, Brazil nuts, sunflower seeds and sesame seeds.
It's important to maintain a good balance between omega-3 fatty acids, which can reduce inflammation, and omega-6 fatty acids, which can promote inflammation. An imbalance between these fatty acids can contribute to disease. We can reach the target ratio by eating more omega-3 rich foods, such as salmon, mackerel and flaxseeds.
4:1 -- recommended ratio of omega- to omega-3 fatty acids in a healthy diet
10:1 -- conservative estimated ratio of omega-6 to omega-3 fatty acids in the average diet
Page 2 of 3 - Read page 3 for fat FAQs
How much fat is OK?
The general recommendation is that children aged one to three should get 30 to 40 per cent of their calories from fat, and children four to 18 should get 25 to 35 per cent of their calories from fat. For adults the recommendation is 20 to 35 per cent of calories from fat. Everyone should limit their intake of saturated fat to less than 10 per cent of total daily calories.
Fat for kids
There's a growing concern that excessive fat intake in childhood may lead to obesity and adult diseases, such as type 2 diabetes. However, it's still important for children to have some fat in their diets.
It's important that young children consume some fat in their diets, and that parents restrict their children's fat intake gradually.
For all children, it's important to look at the kind of fats that they consume. If they're eating lots of snack foods, such as doughnuts, cookies and chips, or processed foods, such as frozen snack foods, it's likely that they're consuming lots of unhealthy trans fats.
Common questions about fat
1. What's the difference between percentage of fat and calories from fat?
The current recommendation is to eat no more than 30 per cent of your calories from fat. Many people think that means that every food they eat must fall into this category. But it's better to look at the total meal. For example, a salad contains very few caloires until you add the dressing. A salad with dressing may contain 100 calories and 10 grams of fat. A gram of fat contains nine calories, so 10 grams of fat would be 90 calories, and this salad would have 90 of its 100 calories coming from fat, or 90 per cent of the calories from fat. Now if you eat that salad with a roll (about 150 calories and two grams of fat) and a piece of fruit (another 110 calories and almost no fat), the total meal would contain 360 calories and 12 grams of fat. So now only 108 of the 360 calories would be fat calories, and the whole meal meal would be 30 per cent fat.
2. How do I know if a food is high in fat?
Multiply the number of grams of fat by nine to get the number of calories coming from fat. Divide that figure by the number of calories in a serving, then multiply that number by 100 to get the percentage of fat. If the result is more than 30 it's not a low-fat food. For example, if a cookie has 100 calories and eight grams of fat, about 70 per cent of its calories comes from fat. An easier method: if a food has less than two or three grams of fat per 100 calories, it's considered low in fat.
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