The Good, The Bad, and The Ugly About Fats
The more scientist discover and publish about fats, the more complex the story becomes. It is the one nutrient we all fear as it is often linked to the main causes of death, including heart attacks, cancer, and stroke. Yet, dietary fat is an essential nutrient, required to form our body’s cell membranes, regulate metabolism, and provide the energy we need. Along with carbohydrates, fats are an important source of fuel for the body, particularly for active people. So let’s try to break the whole fats issue down to what you need to know what’s healthy and what’s not. There are different types of fats and fatty acids, which chemically vary in length and the number of bonds. The number of hydrogens attached to the hydrocarbon tails of the fatty acids as compared to the number of double bonds between carbon atoms in the tail distinguishes between saturated, monounsaturated, and polyunsaturated fatty acids.
Saturated fatty acids have single bonds between the carbon atoms that make up the tail. The carbon atoms are "full" or “saturated”, and therefore cannot take up any more hydrogen and not react with oxygen and heat. Consequently, when they are heated, they will not cause free radical damage in our cells. Most animal fat, such as butter, milk, cheese, and coconut oil, are saturated. The downside however is, that saturated fats can, even without reacting to heat or oxidizing, raise LDL cholesterol (bad cholesterol) and triglyceride levels, while lowering HDL levels (good cholesterol), thus contribute to heart disease. Saturated fats and trans fats are the main dietary factors in raising blood cholesterol.
Unsaturated fats are not quite as bad. They contain the essential fatty acids our bodies need. Two of the most important fatty acids are linoleic acid and linolenic acid that are both commonly found in vegetable oils. Essential fatty acids are important and essential for healthy blood and nerves, normal growth, and good skin. In fact, you may be surprised that Harvard’s Healthy Eating Pyramid places fats near the base of the pyramid, indicating they are okay to eat. Although this recommendation seems to go against conventional wisdom, it is consistent with the overwhelming evidence and with common eating habits. The average American gets one-third or more of his or her daily calories from fats, so placing them near the foundation of the pyramid makes sense. Note, though, that it specifically mentions healthy unsaturated fats, not all types of fat. These healthy fats not only improve cholesterol levels (when eaten in place of highly processed carbohydrates), but can also prevent potentially deadly heart rhythm problems. There are two types of unsaturated fats:
Monounsaturated fatty acids have one or more double bonds between carbon atoms. They contain only one double bond, such that each of the carbon atoms of the double bond can bond with a hydrogen atom, thus it could react with oxygen and heat. Monounsaturated fats have a protective effect on cholesterol levels by lowering the bad cholesterol (LDL) while maintaining higher levels of the good cholesterol (HDL). Examples of primarily monounsaturated fatty oils are olive oil, avocado oil, canola oil.
Polyunsaturated fatty acids contain two or more double bonds, such that four or more carbon atoms can bond with hydrogen atoms. Most vegetable fats are polyunsaturated fatty acids. Polyunsaturated oils (if they are pure and organic) are valuable oils. Polyunsaturated fats tend to help your body get rid of newly formed cholesterol. Thus, they keep the blood cholesterol level down and reduce cholesterol deposits in artery walls. Recent research has shown that monounsaturated fats may also help reduce blood cholesterol as long as the diet is very low in saturated fat. However, they have the capability to react with heat and oxygen and are considered highly unstable. This is why they can be used in salads, but never heated and kept refrigerated. Foods high in polyunsaturated fatty acids include vegetable oils like safflower, corn, cottonseed, soybean, sesame, sunflower oil, fish oils as from cod, salmon, tuna, herring and most nut oils. Salad dressings are usually made from vegetable oils.
While polyunsaturated fats cut cholesterol, they cut both good (HDL) and bad (LDL) cholesterol. Moreover, some cancer studies have reported a link between diets high in polyunsaturated fats and a greater risk of cancer. Triglycerides are the basic unit of fat (including cholesterol) and are composed of three ("tri-") fatty acids individually bonded to each of the three carbons of glycerol. Triglycerides are the chemical form in which most fat exists in food as well as in the body. They’re also present in blood plasma and, in association with cholesterol, form the plasma lipids. Elevated triglycerides may be a consequence of other disease, such as untreated diabetes mellitus. Like cholesterol, increases in triglyceride levels can be detected by plasma measurements. These measurements should be made after an overnight food and alcohol fast. Fatty acids rarely exist in a free form in nature because they are highly reactive, and therefore make bonds spontaneously. Fats that should be avoided include hydrogenated and partly hydrogenated oils, which are trans-fats. Trans-fats are oils whose molecular structure has been altered to increase their shelf life. Trans fats may be monounsaturated or polyunsaturated. A particular class of trans-fats occurs, in small quantities, in meat and dairy products from ruminants. Most trans-fats consumed today, however, are industrially created as a side effect of hydrogenation of plant oils — a process developed in the early 1900s and first commercialized as Crisco in 1911. The end effect of hydrogenation is to add hydrogen atoms to unsaturated fats, making them more saturated, thus more stable. These more saturated fats have a higher melting point and a reduced tendency for oxidation, resulting in a longer shelf-life. Unlike other fats, trans-fats are neither required nor beneficial for health. Our cells use them as they would saturated fats, not being aware of the danger they pose. Eating trans fats makes our bodies prone to premature aging and compromised immunity Trans fats from partially hydrogenated oils are considered to be more of a health risk than those occurring naturally. Saturated fat intake should not exceed 7 percent of total calories each day. Trans fat intake should not exceed 1 percent of total calories each day. Total fat intake (saturated, trans, monounsaturated, polyunsaturated) should be adjusted to fit total caloric needs. Overweight people should consume no more than 30 percent of total calories from fat. Limit foods high in saturated fat, trans fat and/or cholesterol, such as whole-milk dairy products, fatty meats, tropical oils, partially hydrogenated vegetable oils and egg yolks. Instead choose foods low in saturated fat, trans fat and cholesterol. Here are some helpful tips:
- Eat a variety of fruits and vegetables.
- Eat a variety of grain products, including whole grains.
- Eat fish at least twice a week, particularly fatty fish.
- Include fat-free and low-fat milk products, legumes (beans), skinless poultry and lean meats.
- Choose fats and oils with 2 grams or less saturated fat per tablespoon, such as liquid and tub margarines, canola, corn, safflower, soy bean and olive oils.
So, please do yourself and your loved ones a favor: read food labels! Avoid or at least strongly limit commercial snack foods like chips and cookies unless the ingredient list specifically states coconut or palm fat, butter or olive or canola oil. Many products are labeled "No Trans-fats", however they contain sunflower, safflower, corn or soy oil. All chips and cookies are baked. And consequently, those polyunsaturated oils turn into trans-fast. Remember, companies #1 interest is to sell you their products, making you believe they are good for you. Most companies unfortunately are only interested in your money, not in your health. Knowing the facts about fats, including cholesterol, can reduce your risk for a heart attack or stroke. But understanding what fats are and how they affect your health is only the beginning.
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Keywords: food pyramid, good fats, healthy fats, hydrogenized oils, linoleic acid, linolenic acid, mono-unsaturated fats, partly hydrogenated oils and fats, polyunsaturated fats, saturated fats, trans-fats, triglycerides, unhealthy fats