Fats are either saturated or unsaturated. Most unsaturated fats are believed to be good for us. Unsaturated fats can be monounsaturated or polyunsaturated. Monounsaturated fats are found in almonds, avocados, bacon, cashews, ground beef, olives, pecans, peanuts, and pistachios. Polyunsaturated fats are found in corn oil, cottonseed oil, flax oil, soybean oil and safflower oil.
Additionally, there are trans fats, cis fats, and omega fatty acids. In general terms, trans fats are considered bad for our health. Saturated fats are derived from animals and some plants (coconut and palm). Trans fats occur naturally in some meat and dairy products, but there are very few. The majority of trans fat occurs when vegetable oils are heated. Trans fats are found in processed foods.
Cis fats are polyunsaturated and generally good for you unless consumed in extremely high quantities. Cis fats occur naturally. The difference between cis fats and trans fats are the placement of the hydrogen atoms. Unsaturated fats have a double bond in its molecular structure. Hydrogen atoms are on the opposite side of the carbon double bond in trans fats. As a result, the molecule is straight. Cis fats have the hydrogen atoms on the same side of the double bond causing the molecule to kink a bit. Cis fats and trans fats will have identical chemical formulas.
Elaidic acid and oleic acid have the same chemical formula. Oleic acid melts at 13.4 degrees Centigrade. Elaidic acid melts at 45 degrees Centigrade. The molecules are loosely packed in the cis fat, oleic acid, and is liquid at room temperature. The molecules in the trans fat, elaidic acid, are tightly packed and is solid at room temperature. Cis fats are found in Brazil nuts, anchovies, flaxseed, herring, pine nuts, salmon, trout, tuna, and walnuts.
An essential fatty acid is polyunsaturated. The body cannot manufacture essential fatty acids – hence the term ‘essential’. They are made by plants. Our nutritional intake must include the various plants sources making up this classification of fatty acids. There are a couple kinds of essential fatty acids – alpha-linoleic acid (omega-3) and linoleic acid (omega-6).