In nutritious when we speak about fats we mean triglycerides. A triglyceride is a glycerol molecule (COOH) bonded to three fatty-acids. There are three types of triglycerides, Saturated, Monounsaturated, and Polyunsaturated.
Fatty-acids are chains of Carbon atoms, each is bonded to Hydrogen atoms. They are usually 4 to 28 carbon atoms in length. Shorter fatty-acids (less than 8 carbon atoms) are more miscible in water than longer chains (more than 16 carbon atoms). For this reason short chain fatty-acids can raise the acidity of liquids during digestion. It is best to maintain a PH neutral diet.
In a Saturated fat all of the carbon atoms which making up the fatty-acids are bonded (saturated) with hydrogen. These are very stable (meaning they will not oxidize or become rancid) healthy fats. Because the fatty acids are straight they can pack very closely together and therefore are solid at room temperature. Some examples include animal fats, and tropical nut oils such as coconut. One interesting note is that tropical plants must make saturated fats in order to stay rigid in their warm environment. If they didn’t, their leaves would appear wilted. Colder climate plants produce progressively less saturated fats. Saturated fats are great for high temperature cooking because they will not oxidize easily. For better flavor and health try deep frying in lard or duck fat. Once cooled the fat can be strained and used over and over again.
Monounsaturated fats are missing hydrogen atoms from two consecutive carbon atoms. Therefore the two carbon atoms bond together creating a kink. Because of this kink the molecules cannot pack together closely and stay liquid at room temperature. Although they will solidify in the refrigerator. These fats do not go rancid easily and can healthily be used in low temperature cooking. Some examples include Olive oil, Avocado oil, and most nut oils.
Polyunsaturated fats have two or more double bonded carbon atoms and lack four or more hydrogen atoms. These fats cannot pack together closely and therefore are liquid even in the refrigerator. Example are flax-seed oil, most seed oils, soybean oil, omega-6, and omega-3. The omega number corresponds to the position of the first double bond. So, an omega-3 has a double bond at the third position in a fatty-acid chain. These oils go rancid very easily should be refrigerated and never used for hot applications. Unfortunately because these oils are cheap they are the most common for frying.
Fats are good for us. Most vitamins, especially A, D, E, K are fat soluble meaning that without fat they will not be absorptive by the body. We especially want to eat Saturated fats. Saturated fats such as lard, or coconut oil are very hard to oxidize (make rancid) because they are stable. Every Carbon atom is happily balanced with a hydrogen atom.
Studies have shown that 4% of your daily calories should come from Polyunsaturated fats. (4% X 2000calories = 80 calories) try to make 1.5% from omega-3 or 30cal. and 2.5% or 50cal. from omega-6. Flax-seed oil is promoted because it has an unusually high ratio of omega-3 to omega-6 and can therefore restore a proper ration to our bodies. Our diets tend to have far more omega-6 than omega-3. Flax-seed oil contains about 57% omega-3 and 16% omega-6. (Interestingly Flax-seed oil is the same as linseed oil used on furniture, but don’t eat the stuff for furniture it’s oxidized.) These fats are called “essential fatty-acids” because our bodies need them but cannot make them. An egg that feeds on grass and insects will have nearly a perfect equal ratio of omega-3 to omega-6. However, supermarket eggs from hens which feed on grain can have 19 times as much omega-6 as 3. Saturated fats make up approximately 50% of our cell membranes keeping them rigid in our bodies 98 degree climate, just like the tropical plants mentioned earlier. To effectively utilize calcium in our bones 50% of our dietary fats should be saturated. Saturated fats also have antimicrobial properties protecting us against harmful microorganisms in the digestive track.
Cholesterol is a big subject so please ask if you would like me to elaborate. But here are a couple of interesting facts. First your body makes 2000 mg of it per day. Second, study after study has shown that eating cholesterol does not mean that the amount of cholesterol in your blood will rise. It most cases it has no effect. Lastly, the average person eats 100mgs of cholesterol a day, therefore even removing it from your diet entirely would only result in a 5% decrease of cholesterol levels. Cholesterol is vital to the brain, organ, and the creation of most hormones. Low cholesterol can decrease the brains production of Serotonin and lead to depression. This is why statins (cholesterol lower drugs) can cause depression. Organ meats, raw mollusks and crustaceans are all excellent sources of cholesterol. Mothers milk is naturally very high in cholesterol and helps brain development in babies. Oxidized cholesterol is perhaps America worst enemy. This is what forms the plaque build up in arteries. It is formed when fats are exposed to high temperatures. Some examples are powdered eggs, powdered milk, polyunsaturated fry oils. Unfortunately powdered milk and eggs are used in processed foods including supermarket milk and ice cream among others.
Margarine and Cis vs. Trans Fat
Margarine is primarily made from corn, cotton seed, or soy bean oil depending which is cheaper at the time. 4.5 bushels of corn are needed to make one gallon of corn oil. That means corn is only about 2.4% oil. Without government subsidy corn oil would not be viable. The oil is extracted from these sources using solvents, usually hexane. To remove the hexane the oil must be boiled causing the oil to oxidize. Then nickel rust is added to the oil to act as a catalyst where hydrogen can bond. Under high pressure and temperature hydrogen gas is bubble through the oil until it becomes saturated or solid. Emulsifiers and corn starch are added for a smooth constancy. At this point the product smell unpleasant so it must be deodorized with steam. However, because of the added nickel the margarine is an unappealing gray color. Therefore it must be bleached till white. Lastly, coloring and synthetic butter flavor is added. Cis fats can be thought of as common natural fats. Margarine is a trans fat, so called because the position of a carbon atom has been transfered to straighten out the fatty acid. Now straitened out the molecules can pack closely together and resemble a solid saturated fat (like butter). This is a problem because your body can’t see the difference between a natural saturated fat and a man made one. Your body then uses this trans fat to build cell walls. Cell walls are very important because they control the flow of chemicals in and out of the cell. With a defective cell wall made of trans fats there is no proper regulation.