“Your LDL’s are too high,” reports the doctor. “Cut back on fat to decrease your risk of cancer,” touts the magazine article. That’s great to know. But how?
You may have the impression that fat is bad for you. It may come as a surprise that lipids (the general term for fats) are very valuable.
Fat is a concentrated source of energy. It supplies 9 calories per gram.
It supplies essential fatty acids needed by the body.
Fat carries and transports the fat-soluble vitamins A, D, E, and K.
Fat helps the body use protein and carbohydrates more efficiently.
Fat is a component of every cell wall.
Deposits of fat in the body serve to support and cushion vital organs, and to provide insulation.
Fat is the body's chief storage from for energy and work.
Fat carries the compounds that give foods their aroma and flavor.
Types of Fat
The most common forms of fat in foods and in the body are known chemically as triglycerides, making up about 95% of the total. Triglycerides are made up of three molecules of fatty acids and one molecule of glycerol, an alcohol.
In addition to triglycerides, food fats also contain phospholipids and sterols. The most famous sterol is cholesterol. Cholesterol is a fat-like substance found in animal foods and in the body’s blood, brain and nervous systems. It is essential to the structure of every cell in the body. Cholesterol is related to vitamin D and the steroid hormones, such as cortisone and sex hormones.
Dietary Cholesterol is found in the foods eaten. It is found only in foods of animal origin, never in plant sources. The dietary goal is to limit intake to <300 milligrams each day.
Serum (blood) Cholesterol flows through the bloodstream. Cholesterol is essential for certain body components such as hormones, cell walls and various functions. Therefore your body manufactures most of its blood cholesterol. Some is also absorbed through the foods you eat. The goal is to have a total blood cholesterol level of <200 milligrams per dL.
What LDL and HDL Mean
During digestion, carbohydrates and proteins are dealt with first. However by the time fat reaches the small intestine, it receives all the attention. Bile is squirted into the mixture to emulsify or break up the fat globules, allowing enzymes to attack the chemical bonds on the triglycerides. The fats are digested and broken down into fatty acids and glycerol, and pass into the intestinal cells.
Since blood and other body fluids are watery, fats need a special transport system to travel around the body. They travel from place to place mixed with protein particles, called lipoproteins. There are 4 types of lipoproteins with very distinct jobs:
Chylomicrons are made by the intestines for transporting “new” fat to the body’s cells. These carry mostly triglycerides.
Very-Low-Density-Lipoproteins (VLDL) are made by the intestines and liver to transport fats around the body. These carry mostly triglycerides.
Low-Density Lipoproteins (LDL) are made by the liver to carry cholesterol to the body’s cells and tissues, and may form deposits on the walls of arteries and other blood vessels. They are therefore considered the lazy, or “bad,” cholesterol. The goal is to have an LDL level of < 100 milligrams per dL.
High-Density Lipoproteins (HDL) pick up and carry excess cholesterol from artery walls and bring it back to the liver for processing and removal. They are therefore considered the healthy, or “good,” cholesterol. The goal is to have an HDL level of >45 milligrams per dL.
L = LAZY
What Exactly are Fatty Acids?
Fatty acids are the major component of triglycerides, the material of fat. Fatty acids are energy-rich chemical chains that come in three forms:
Monounsaturated Fatty Acids:
Liquid at room temperature, decrease total blood cholesterol but maintain your HDL (healthy/good) cholesterol. Sources include: certain oils and margarines (canola, olive, peanut, sesame), avocado, nuts (almonds, cashews, hazelnuts, macadamia, pecans, peanuts, pistachios), peanut butter, olives, sesame seeds, tahini paste.
Polyunsaturated Fatty Acids:
Liquid or soft at room temperature, decrease total blood cholesterol by lowering both the LDL (lazy/bad) cholesterol and the HDL (healthy/good) cholesterol. Sources include: certain oils and margarines (corn, safflower, soybean), walnuts, mayonnaise, most salad dressings, pumpkin and sunflower seeds.
Omega-3 fatty acids are highly polyunsaturated. They are mostly found in seafood, especially high-fat fish, such as albacore tuna, mackerel, and salmon.
Saturated Fatty Acids:
Solid at room temperature and increase total cholesterol and bad cholesterol. Sources include: butter, cheese, cream cheese, sour cream, cream, ice cream, whole milk, bacon, bacon grease, lard, beef, pork, poultry, shortening, coconut, coconut oil, palm oil, palm kernel oil, cocoa butter.
Hydrogenation is a food production process that changes liquid oils to solid at room temperature. Trans fatty acids are a type of fat formed by hydrogenation. It acts like a saturated fat and increases your LDL (lazy/bad) cholesterol and total cholesterol levels. To learn more about trans fats, read Translating those Trans Fats, located in the Nutrition Resource Center.
The body’s cells can utilize the fatty acids directly as a source of energy. Any not used are stored in the fat tissue as a reserve supply of energy. Fat cells are able to expand almost indefinitely in size and quantity.
Diet & Fat Guidelines
One of the quickest and healthiest ways to reduce calories and lose weight is to cut back on the fat. Eating a diet low in fat is an important step in keeping your heart and arteries in tip-top shape too. The overall goal is to avoid excess fat, especially saturated fat and LDL cholesterol.
Limit your intake of total fat to <30% of your total calories each day. This is about 45-65 grams each day.
Limit your intake of saturated fat to <10% of your calories each day. This is about 15-25 grams each day.
Limit your intake of cholesterol to <300 milligrams each day.
Remember that all fats and oils are not created equal; however all fats and oils are still high in calories. Things to keep in mind:
Monounsaturated fats help to lower the LDL (lazy/bad cholesterol) while NOT lowering the HDL (healthy/good cholesterol). These fats are the most heart friendly.
Polyunsaturated fats help lower the LDL (lazy/bad cholesterol) but they also lower the HDL (healthy/good cholesterol). So they are only somewhat heart healthy.
Saturated fats raise the LDL (lazy/bad cholesterol) and increase the risk of heart disease. Therefore, they are not heart healthy.
Trans-fatty acids can raise the LDL (lazy/bad cholesterol) and triglycerides levels, and lower the HDL (healthy/good cholesterol). They are not heart healthy.
Check out these other important nutritional items as well.
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