The Science of Fats
All fats are composed of hydrogen, carbon and oxygen atoms. Basically, an atom is like a miniature sun, called the nucleus, which is made of protons and neutrons. Orbiting around this miniature son are electrons that are like the planets, always staying in the same orbit/distance from the nucleus. There may be more than one electron in the same ring circling the nucleus. Everything on earth and in the universe is made up of atoms. There are different types of atoms, called elements, 90 of which occur in nature. The number of protons in the nucleus of the atom determines which element it is. Hydrogen, the smallest element has only 1 proton, carbon has 6 protons, and oxygen has 8 protons.
Here is a 3-D picture of a carbon atom with the blue representing electrons circling around the 6 protons and 6 neutrons in the center:
Oxygen has one ring with 2 electrons available to bond to other elements and Hydrogen has one ring with one electron circling around available to bond to other elements. Carbon has 4 bonds to connect with other atoms to form a molecule, oxygen has 2, and hydrogen has one. Atoms connect by sharing one or more electrons in their outer electron rings. In water (H20) you have an oxygen atom bonding to two hydrogen atoms - H-O-H.
Saturated Vs. Unsaturated
The building blocks of all fats are called fatty acids. Simply put, they're chains of carbon atoms connected like beads on a string, with hydrogen atoms on each carbon atom and an acid (carboxyl) group on one end. Two carbon atoms next to each other can share either one or two bonds in fats.
The type of bond determines the number of hydrogen atoms each carbon atom can hold. The two carbon atoms on the left, above, are held together by a single bond, and are said to be 'saturated' because they're holding all the hydrogen atoms they can. A saturated fat is saturated with hydrogen atoms. The two carbon atoms. above, on the right, are connected by a double bond (they are sharing two electrons in their outer electron rings) are said to be 'unsaturated' because each carbon atom could possibly hold on to one more hydrogen atom if the two carbon atoms weren't doubly bonded to each other.
So a carbon atom that is completely bonded to hydrogen atoms is completely saturated. Saturated oils tend to be solid at room temperature because they pack closely together. They tend to be stable and not bond with other atoms even when heated.
Unsaturated fats tend to be liquid at room temperature because the double carbon bonds tend to kink and keep the molecules from packing tightly together. Unsaturated is not necessarily better for you – as unsaturated fats are more unstable and lead to oxidation and free radical damage. Many mono and poly unsaturated fats tend to form carcinogens when heated at high temperatures, while saturated fats remain stable and do not form carcinogens.
The building blocks of all fats are called fatty acids. Fatty acids are chains of carbon atoms connected like beads on a string, with hydrogen atoms attached to each carbon carbon atom and an acid (carboxyl) group on one end of the chain of carbon atoms. A carboxyl group consists of the following molecules hydrogen, oxygen, carbon, connected to another oxygen:
The number of carbon atoms in each fatty acid chain, the type of bonds between the carbons, and how many hydrogen atoms the carbon atoms are holding on to, all determine the type of fat and its characteristics. Fatty acids with one double bonded pair of carbon atoms in the chain are called monounsaturated. Fatty acids with two or more pairs of bonded carbon atoms are called polyunsaturated. Below is a fat that is monosaturated because it has one pair of carbon atoms connected with a double bond (so they are not saturated with hydrogen):
Most fats in are body and in foods are in the form of tryglyceride molecules – one glycerol molecule with three fatty acids attached. Below is a Glycerol molecule, which consists of hydrogen, carbon and oxygen:
The number of carbon atoms in a fatty acid chain determines whether it is short, medium or long chain:
Generally short and medium chain tryglycerides are more easily digested and used by the body.
Omega 3, 6 and 9 Oils
All Omega Fats, 3, 6, and 9 consist of a carbon chain that has two ends – the acid end (COOH) that we saw examples of above and a methyl group end. A methyl group is one carbon atom with 3 hydrogen atoms attached:
Omega fats are unsaturated – the difference between Omega 3, 6, and 9 is the position of the double carbon bond (C=C) from the methyl group end of the chain:
These Omega oils may also have other double bonds in their molecules. Below is the chemical structure of linolenic acid, a common Omega 6 fatty acid found in many vegetable oils (note that one double carbon bond is positioned 6 carbon atoms away from the methyl group at the right end of the molecule):
Omega 3 is considered “essential” because the human body cannot manufacture it – it must be obtained from food. However humans have the ability to form the long chain Omega 3 fatty acid EPA (20 carbon atom chain) andOmega 3 DHA (22 carbon atoms) from the shorter chain Omega 3 8-carbon Alpha Linolenic Acid (ALA). The Omega 3 oils most critical to brain function are DHA and DPA. To complicate matters further, DHA is usually placed on the glycerol molecule in positions 1 and 3 in fish oil, while in humans can only use DHA whenit is placed in position 2. This means that after consuming fish oil, the human body must rearrange the DHA into the Number 2 position to use it and during this process, some percentage of the DHA is lost as this process is not efficient.
Omega 6 and 9 are non-essential because the body can manufacture them. Linolenic acid and Arachidonic acid are Omega 6 oils. Oleic acid (found in olive oil and other vegetable oils) and erucic acid (found in canola oil) are examples of Omega 9 oils.
Because Omega Fats are unsaturated these oils must be used fresh and not allowed to oxidize (become rancid) as they may form compounds that are detrimental to health and generate free radical damage. It is best to keep these oils sealed and refrigerated once opened.
Trans fat is the common name for a family of artificially created unsaturated fats such as margarine and shortening. These fats are associated with increased risk of heart disease and stroke. Health authorities worldwide recommend consumption of transfats be reduced to trace amounts.
Unsaturated fats can have different shapes or configurations depending on which side of the double bond the hydrogens end up:
In a 'cis' (pronounced 'siss') formation, the hydrogens are on the same side. With 'trans' formations, they're on opposite sides of the double bond. The linear stick and letter figures I've been using don't really show the true shapes of the cis/trans unsaturated fatty acids accurately. In actuality, as mentioned above, there's a lot of bending going on whenever double bonds enter the scene. When vegetable oil processors thought it would be cool to make their products stay solid at room temperature, like butter and lard, they came up with a process called hydrogenation which yielded margarine and shortening. Crisco is hydrogenated cottonseed or soybean oil. Nobel Prize winner Paul Sabatier (1854-1941) is considered the father of the hydrogenation process. He discovered in 1897 that the metal, nickel, catalyzes, or facilitates, the attachment of hydrogen to carbon compounds.
In the actual process, workers heat the oil to very high temperatures and bubble hydrogen gas through it in the presence of nickel or some other catalytic metal. Since the vegetable oils are unsaturated, they can take on a few more hydrogens. When they do, the molecule stiffens, and the fat is now closer to a solid. They can control just how firm it gets by how long they pump the gas through. That's why you'll sometimes see the term 'partially hydrogenated' on ingredient labels.
What also happens during hydrogenation, or later, during high heat cooking with the processed oils, is the formation of molecules so strangely configured that they're completely unsuitable for use in our bodies. In addition, the double bonds in these foreign fatty acids are easily broken, allowing the formation of free radicals- highly reactive molecules with an unpaired electron, just looking for something to grab on to.
Promotion of breast cancer, heart disease, diabetes, weakened immune systems and hormonal dysfunction are just some of the maladies for which studies have implicated these unnatural trans fats.
What About Cholesterol?
Cholesterol is a waxy steroid of fat. Cholesterol is essential for all animal life. It is an essential structural component of mammalian cell membranes and is required to establish proper membrane permeability and fluidity (critical to communication between neurons). In addition it is an important component for the manufacture of bile acids, steroid hormones and Vitamin D.
Animal fats are complex mixtures of triglycerides with lesser amounts of phospholipids and cholesterol. All animals fats and eggs contain cholesterol, as does human breast milk. Having too low levels of cholesterol can lead to neurodegenerative conditions such as Parkinson’s and Alzheimer’s, depression, cancer, and stroke. Statin drugs that lower cholesterol also increase risk of neurodegenerative conditions and congestive heart failure.
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