Fats:
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It's difficult to read a newspaper or watch the evening news without hearing something new about fat and its relationship to disease. High-fat diets are strongly linked to an increased prevalence of obesity as well as an increased risk of coronary artery disease, high blood pressure, diabetes mellitus, and certain types of cancer. Health experts advise us to limit our total fat intake to about 30% of total calories. They also recommend that we limit our consumption of saturated fat (the type of fat most commonly found in meat and dairy products) to less than 10% of our fat calories and that the fat we do consume is mostly monounsaturated or polyunsaturated. These changes have been shown to reduce our risk of a variety of diseases.
Fat as a Nutrient :
Fat is an essential nutrient because our bodies require small amounts of several fatty acids from foods (known as essential fatty acids) to build cell membranes and produce several essential hormones, including the steroid hormones testosterone, progesterone, and estrogen, as well as the hormone-like prostaglandins. Dietary fats also allow one type of vitamin, fat-soluble vitamins (A, D, E, and K), to be absorbed from foods during digestion. Fats aid in the transport of vitamins through the bloodstream to their destinations. Fat in our bodies also serves as a protective insulation and shock absorber for vital organs. Fat, as a macronutrient, provides energy (calories). Food fat contains approximately 9 calories per gram, which is more than twice as many calories as the same amount of protein or carbohydrate. As a result, high-fat foods are regarded as "calorie-dense" sources of energy. Any dietary fat not used for energy by the body is stored in fat cells (adipocytes), which are the constituents of fat (adipose) tissue. The Dietary Guidelines for Americans recommend that no more than 30% of our calories come from fat, with only one-third of that coming from saturated fat.
Sorting Through the Fats:
The amount and type of fat we consume have an impact on our health. Fats are molecules, and they are classified based on the chemical structures of their constituent parts. But you don't have to be a chemist to understand the relationship between the different fats in foods and the effect these fats have on disease risk. Some definitions will be useful. Dietary fats, also known as triglycerides, are the fats found in foods. They are molecules composed of fatty acids (chain-like carbon, hydrogen, and oxygen molecules) linked in groups of three to a glycerol backbone. When we eat fat-containing foods, the fatty acids are separated from their glycerol backbone during digestion.
Fatty acids are classified as saturated or unsaturated based on the number of hydrogen atoms attached to a carbon chain. Fat in foods is made up of fatty acid mixtures—some fats are mostly unsaturated, while others are mostly saturated.
Monounsaturated fatty acids are those with one pair of hydrogen atoms missing from their carbon chain. Canola, nut, and olive oils are high in monounsaturated fatty acids and are liquid at room temperature. A diet that includes only small amounts of animal products and provides the primary source of fat as monounsaturated fat (often in the form of olive oil) has been linked to a lower risk of coronary artery disease. People who live in the Mediterranean Sea region are accustomed to eating this type of diet. Polyunsaturated fatty acids have a carbon chain that lacks two or more pairs of hydrogen atoms. Polyunsaturated fats can be found in safflower, sunflower, sesame, corn, and soybean oil (which are also liquid at room temperature). Linoleic and linolenic acid are polyunsaturated fats found in essential fatty acids. Polyunsaturated fats, like monounsaturated fats, lower blood cholesterol levels and can be used in place of saturated fats in the diet.Saturated fatty acids, also known as saturated fats, are fatty acids that have been "saturated" with hydrogen. These fats are primarily found in animal-derived foods such as meat, poultry, dairy products, and eggs, as well as coconut, palm, and palm kernel oil (also known as "tropical oils"). Saturated fat-rich foods are firm at room temperature.Because a high intake of saturated fats raises your risk of coronary artery disease, nutritionists recommend that you consume less than 10% of your calories from saturated fats.
Omega-3 fatty acids are a type of polyunsaturated fatty acid found in fish (particularly tuna, mackerel, and salmon) and some plant oils, such as canola (rapeseed) oil. These fatty acids have made headlines due to the discovery that people who eat fish on a regular basis appear to have a lower risk of coronary artery disease. Omega-3 fatty acids appear to be important in your ability to fight infection. Hydrogenated fats are the result of a process that solidifies and stabilizes unsaturated fats at room temperature. The addition of hydrogen atoms during the hydrogenation process results in a saturated fat. Hydrogenation produces trans-fatty acids. Increased consumption of these fats is concerning because they have been linked to an increased risk of coronary artery disease. Stick and tub margarine, commercial baked goods, snack foods, and other processed foods all contain hydrogenated fat.Cholesterol is a waxy, fat-like substance that serves as a precursor for bileacids (required for digestion), vitamin D, and a critical group of hormones (the steroid hormones).Our livers can produce nearly all of the cholesterol required for these vital functions. Meat, poultry, milk, butter, cheese, and eggs are the only foods that contain dietary cholesterol. Plant-based foods, such as fruits, vegetables, nuts, seeds, legumes, grains, and the oils derived from them, are cholesterol-free. Because the average large egg contains about 210 milligrams of cholesterol (only in the yolk), and the recommended daily cholesterol intake is 300 mg or less, eggs are the food most often associated with cholesterol. However, because cholesterol is found in both the lean and fat portions of meat, meat contributes a higher proportion of cholesterol to the diet for most people than eggs. Shellfish have an unjustifiable reputation for being high in cholesterol Their cholesterol and total fat levels are actually quite low.
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Substitutes for Fat:
The commercial food industry has developed low- or lower-fat versions of many foods using various fat replacers to appeal to our desire for lower-fat substitutes for our favorite high-fat foods. Until recently, fat substitutes were always proteins or carbohydrates, such as starches or gels, but the types of foods that could be prepared with these fat substitutes were limited by their inability to withstand high frying temperatures.The FDA approved the first non-caloric fat, olestra, for use in the manufacture of savory (non-sweet) snacks in 1996, after a lengthy period of development, safety testing, and governmental review (such as crackers and chips). Olestra is the first heat-resistant fat substitute because it is a modified fat, allowing it to be used to make fried foods. Furthermore, olestra imparts the flavor and creamy "mouth feel" of high-fat foods to foods.Olestra's FDA approval was contentious for two reasons. First, if approved and accepted, this artificial ingredient would be the first in history to be consumed in quantities comparable to the amounts of fat, carbohydrates, and proteins we currently consume from food sources. In other words, these novel, previously unknown substances may become important components of some people's diets, and There would be no historical precedent to tell us what the substances would do in our bodies. Despite controlled studies demonstrating its safety, some scientists predicted that the substance would cause serious gastrointestinal problems. However, the predicted intestinal problems were not significant in the first year of olestra-containing food availability. In tests where volunteers ate large amounts of olestra-containing potato chips or regular potato chips without knowing which type they were eating, no differences in gastrointestinal complaints were found between the two groups. Second, olestra tests revealed that it inhibits the absorption of fat-soluble compounds (vitamins A, D, E, and K, as well as some carotenoids) from foods eaten concurrently with olestra-containing foods, while having no effect on the absorption of other nutrients or the body's stores of fat-soluble vitamins. To compensate for olestra's effect on fat-soluble vitamin absorption, foods containing olestra have trace amounts of these vitamins added to them. At the time of writing, the list of foods that can use olestra as a fat substitute is quite limited. Some concerns remain about the product's long-term safety, despite the fact that long-term studies in young, growing animals and several human studies have found no negative effects. How should you decide whether or not to include foods containing fat substitutes in your diet, and how much of these foods should you include? Small amounts of olestra-containing foods appear to be safe from a health standpoint. However, from a purely nutritional standpoint, most foods containing fat substitutes are snack foods with little nutritional value. Furthermore, these foods are not calorie-free. Many continue to be high in calories, and some foods containing carbohydrate fat replacers are even higher in calories than their higher-fat counterparts, making them calorie-dense, nutritionally poor foods. It's fine to eat these foods in moderation, but better low-fat snack options include fruits, vegetables, nonfat yogurt, and whole-grain pretzels and breads.
The Final Word on Fats:
Although dietary fat provides energy, high-fat diets, particularly those high in saturated fat, increase the risk of developing diabetes, coronary artery disease, high blood pressure, and several types of cancer. Because of this increased risk, health experts advise us to reduce our intake of total and saturated fats by:
• eating more fruits, vegetables, and whole-grain foods that are naturally low in fat, and preparing them with a minimum of added fats.
• eating low-fat dairy products such as nonfat milk, yogurt, and low-fat cheeses.
• limiting our daily consumption of red meat, poultry, and fish to 5 to 7 ounces.
• selecting lean cuts of red meat and poultry, removing the skin before eating poultry, and preparing the meat in a way that uses little or no additional fats.
• selecting omega-3 fatty acid-rich fish and preparing it with little or no added fat.
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