Fat includes what we commonly call “fats” and “oils”. “Fats” in the everyday sense are solid at room temperature while oils are liquid. Fats are made up of fatty acids that give fats their different flavors, textures and melting points. There are two types, saturated and unsaturated. Nutritionist calls both saturated and unsaturated fats as “triglycerides”. A triglyceride has three fatty acids attached to a substance called glycerol.
Fat’s basic component is therefore the triglyceride, which consists of a glycerol base with three fatty acid chain attached. The difference between the various types of fats depends upon which fatty acids are in the triglyceride.
Of these unsaturated fatty acids (linoleic and linolenic acid) must be taken in the diet and are thus called essential fatty acids.
When digested, triglycerides are broken down into fatty acids and glycerol, which can then be absorbed.
There are four main types of fat, each with different chemistry: saturated, monounsaturated, polyunsaturated, and trans fat. Fats are made up of fatty acids. The main difference among fats is the extent of saturation of the chemical bonds in the fatty acids. Saturation is measured by the amount of hydrogen atoms that are connected to the carbon chain.
Saturated Fat (SFA)
Saturated fathas a fat molecular structure condensed with hydrogen, where all the existing space in the fat molecular structure is occupied. SFA contains fatty acids like stearic acid, palmitic acid, and butyric acid. Having high melting point, saturated fats are usually in solid forms at room temperature. SFA is found most in animal foods like meat, poultry, butter (which contain 66% SFA) and whole milk. Other sources of SFA are coconut, palm and palm kernel oils. This type of fat is very visible in beef, while less visible in others such as palm oil.
In the modern day diet, most of the SFA in our body is derived from consumption of animals reared in commercial animal farms. Not only are these animals fed hormone to speed their growth and antibiotics to prevent diseases, they are also grain fed to enhance their productivity and taste. Upon maturity, they are sent to the slaughtering house. Researchers have shown that the amount of saturated fat found in such animals to be higher than those animals that are allowed to run free and fed organic food. This higher level of SFA is transferred to us upon consumption of their meat.
SFA also comes from hardened or hydrogenated vegetable oils (e.g. vegetable fat, hardened or hydrogenated marine/fish oils), biscuits, cakes, tarts, pie crust, pastries, chocolate, coffee creamers, milk or dairy solids, ice cream, non-dairy cream substitutes, shortening.
While many studies linked a high intake of SFA to increased risk of cardiovascular disease, the exact mechanism is not fully understood. It appears that the effect of SFA intake on cardiovascular disease incidence is only mediated through its effect on raising LDL cholesterol levels. If LDL cholesterol level is under control, then SFA has no independent effect. In other words, if the LDL cholesterol and HDL cholesterol levels are within normal limits, then adjustment of saturated fat intake in the diet will have little benefit.
SFA can be obtained from animal and plant sources, although animal sources are most common. The best animal source of SFA comes from cattle, poultry, and fish. Meat from free roaming grass fed cattle, poultry fed organic food instead of grain fed, or fish have the least SFA, while commercially raised grain fed cattle or chicken raised in a chicken farm have the most SFA. It’s best to obtain your SFA from consuming meat from free range animal or from vegetarian sources such as seeds and nuts. Broiling is more encouraged than pan-fry meats, like hamburger, chops and steak. Lean meats or extra lean meats are also recommended.
Monounsaturated Fat (MUFA)
Monounsaturated fat (MUFA) is fat that has one double bond in its structure. At room temperature, MUFA is in an oil and liquid form. When placed in the refrigerator, MUFA will turn cloudy. MUFA is derived from plant sources, such as canola, peanuts and olive. Olive oil is the highest among most vegetable oil. MUFA is also found in olive oil margarine, canola margarine, and peanut butter.
MUFA is labeled as a “good” fat and for good reasons. Studies have shown that for each 10-gram increment intake of monounsaturated fat in the diet, there is a significant reduction in the relative risk for invasive breast cancer.
Epidemiological studies have shown that people that live in Mediterranean countries have one of the lowest rates of cardiovascular disease in the world. This population group takes in olive oil as their main source of fat. Olive oil is high in MUFA. Whether longevity is directly related to the high olive oil in the diet remains unknown. It has been postulated so, although there are opposing and conflicting scientific evidence, including one study where mice and monkeys fed monounsaturated fats — such as olive oil — develop more hardening of the arteries in major blood vessels than animals fed polyunsaturated fats.
MUFA’s anti-aging properties include:
a.Lowering the oxidation of LDL cholesterol and thus, slowing a crucial process of atherosclerotic plaque formation.
b.Lowering the triglyceride levels, a form of circulating fat found in plaque and cholesterol.
c.Promoting high level of HDL cholesterol and hence, decreasing the risk of heart disease.
The largest benefit in terms of reduced risk of cardiovascular disease is found when SFA are replaced with MUFA. Since SFA increase risk of heart disease and MUFA reduce that risk, changing both at the same time maximizes the benefits.
Polyunsaturated Fat (PUFA)
Polyunsaturated fat (PUFA) are fat made up with fatty acid chains (like linoleic acid and linolenic acid) that contains two or more double bonds. PUFA are primarily found in vegetable oils and fish sources. Omega-6 PUFA is derived from vegetable oils. Salad dressing, margarine, and mayonnaise containing these oils are therefore high in PUFA. Omega-3 PUFA are found primarily in fish. At room temperature, PUFA is in liquid form. Even in cold temperatures, PUFA still remains as liquid since it have a lower melting point than MUFA or SFA.
Both MUFA and PUFA tend to be liquid at room temperature. In order to firm them up, food processors will ” hydrogenate” PUFA. This processing results in a type of fat call trans fat. Trans fat remains solid at room temperature. They can be then turn into shortening and margarine. By increasing its resistance to oxidative damage, the oil’s shelf life is extended. Its commercial value is increased. Trans fat is commonly used in cakes, donuts, fast foods, and fried foods.
While trans fatty acid may be classified as hydrogenated polyunsaturated fats due to their chemical structure, they generally are like saturated fats in terms of their effects on cholesterol.
Without a doubt, trans fat is the worst kind of fat. During the hydrogenation process, the chemical structure of the natural fatty acid is changed from their original cis- configuration to unnatural trans- configuration. Trans-isomerization alters the 3 dimensional configuration of dietary fatty acid, causing damage to the cell membranes and altering the function of phospholipid-dependent enzymes contained in these membranes. This altered fluidity increase cell membrane permeability. The active transport enzymes for sodium, potassium, calcium, and magnesium are impaired. Such cell membrane is also subject to free radical attack and damage. A high intake of trans fat has therefore been linked to a variety of free radical and degenerative conditions such as cancer, arthritis, and cardiovascular disease.
Trans fat also increases the level of triglyceride and LDL cholesterol. More significantly, trans fat reduces the level of “good” HDL cholesterol that often related to the lower risk of cardiovascular diseases. Researches revealed that a replacement of 2% of trans fat consumed with MUFA (like nuts, olive oil and flaxseed oil) could reduce heart disease risk by 53%.
Naturally occurring trans fat is quite rare, being limited to a small amount in milk as a consequence of gut bacteria in dairy cows. Clearly this is not the kind of fat Mother Nature intended us to have in our body.
People with digestive system issues should avoid cooking oil or processed fats. Mother Nature has provided sufficient source of fats in the whole grain food. Fruits, vegetables, fishes in our daily diet give us plenty of fat elements that we need for our health. Remember, even lettuce contains vegetable oil.