Good fats, bad fats, trans fats, omega-3, omega-6, hydrogenated, unsaturated… it gets confusing trying to sort out which fats we are supposed to eat and which ones to avoid. With a little explanation and a little chemistry you will understand the language of fats – and more importantly know how and why to include the healthy ones in your diet.
Healthy fats are a necessary part of the human diet and help make up nerve and brain tissue, cell membranes, and beneficial steroid hormones such as estrogen, testosterone, and vitamin D. Fats are necessary for us to absorb fat-soluble vitamins (K, A, D, E) and they can fight inflammation. However, the wrong fats are linked to many ailments including heart disease, cancer, and inflammatory and autoimmune diseases.
Fats in the diet are primarily fatty acids (FAs) consisting of the elements carbon (C), hydrogen (H) and oxygen (O). The C chain acts as a skeleton with H attached all along the chain and at one end of the chain is a chemical group called carboxyl (-COOH). The C atoms are bound together by a single or double bond depending on whether two H or one H atoms are attached. When a C atom has only one H attached it has room for another, and the bond to its neighboring C is double. With two Hs attached the C atom is full and attaches to its neighbor by a single bond. This determines the basis for “saturated” or “unsaturated” fatty acids and also “trans” fats.
Saturated fatty acids (SFAs) have all the H that the C atoms can hold, the FA is “saturated” with H atoms, and there are no double bonds in the C chain. Monounsaturated fatty acids (MUFAs) have only one C atom with a single H attached and only one double bond in the C chain. Polyunsaturated fatty acids (PUFAs) have more than one double bond. The double bonds, and where they are located along the C chain determine most of the health properties, good or bad, of FAs.
Omega-3 and Omega-6 Fatty Acids
FAs have common and scientific names. The scientific name is based on Greek and refers to how many C atoms long the chain is, how many double bonds are present, and where they are located. The C atoms are labeled in Greek also, as alpha, beta, gamma, and so on until the end, which is always “omega”, being the last letter in the Greek alphabet. The alpha carbon is always at the carboxyl end of the FA and the location of a double bond from the omega end of the FA determines the familiar omega designation.
Omega-3 and omega-6 FAs are “essential” in that must be included in the diet because humans cannot make them from other FAs. Those with a double bond three C atoms from the omega end are called omega-3 and those with a double bond six C atoms from the omega end it is called omega-6.
The omega-6 FAs lead to inflammation, breaking down first to Arachidonic Acid (AA) then into the inflammation producing prostaglandins and leukotrienes. Drugs such as Ibuprofen and Celebrex inhibit the enzymes that break down AA. So do curcumin and other herbs, with far less side effects. The omega-3 FAs will inhibit the breakdown of AA and thus lower inflammation. Sugar, high-glycemic foods, and insulin will encourage AA breakdown leading to inflammation.
Nature intended for humans to get about a 2:1 ratio of omega-6:omega-3 FAs, yet in America we are getting a 20:1 ratio of these FAs in our diet. Foods high in Omega-6 include vegetable oils, salad dressings, chips, fast foods, cookies, candies, cakes, pastries, dairy, eggs and red meat. We generally get lots of omega-6 from fried, packaged and processed foods. Omega-3 rich foods include dark fish, such as salmon, flax or chia seeds, walnuts, and many vegetables.
Trans-Fats and Hydrogenated Oils
The Latin prefixes “cis” and “trans” describe the orientation of the H atoms on either side of a double bond between C atoms. Cis means “on the same side” and trans means “on the other side”. Naturally occurring FAs generally have the cis configuration, which causes the FA to bend at that bond making a “V” shape. The trans configurations look more like a straight line. Trans-fats are not natural yet when consumed they are incorporated into cell membranes and alter the normal functions of the cell. They raise cholesterol and increase the risk of heart disease. They also have a detrimental effect on the brain and nervous tissue, altering nerve cell communications and causing nerve degeneration.
Hydrogenated oils have more H atoms forced into the FA in order to reduce or eliminate the number of double bonds. Unsaturated fats are more prone to oxidation and going rancid so hydrogenation increases the shelf life. Fully hydrogenated oils are hard and waxy so manufacturers stop the process at the desired oil texture, leaving “partially hydrogenated” oils. The high temperatures and catalysts used in this process create more of the unhealthy trans-fats.
Triglycerides (TG) are the main form of fat in vegetable oils and animal fats. A TG is a chemical compound formed from one molecule of glycerol and three FAs thus the name tri-glyceride. Oils have varying amounts of different FAs attached to glycerol and as such are made up of different proportions of saturated and unsaturated FAs.
Artificial fats such as Olestra are created from sucrose instead of glycerol, with up to eight FAs attached, which makes it too large to be metabolized. It passes through the body unchanged which causes less calories to be absorbed from the food, but it can cause side effects such as diarrhea or depletion of fat-soluble vitamins.
I hope this primer on fats and fatty acids helps to sort out and define some of the language of fats. With this foundation I will continue in next week’s column with practical advice on which oils to include in your diet and which oils to avoid.
Scott Rollins, MD, is Board Certified with the American Board of Family Practice and the American Board of Anti-Aging and Regenerative Medicine. He specializes in bioidentical hormone replacement for men and women, thyroid and adrenal disorders, fibromyalgia and other complex medical conditions. He is founder and medical director of the Integrative Medicine Center of Western Colorado (www.imcwc.com) and Bellezza Laser Aesthetics (www.bellezzalaser.com). Call (970) 245-6911 for an appointment or more information.