To understand fats requires knowing a little bit about their structure. When we can visualize this, we can appreciate why some fats are more stable and suitable for cooking. We can also appreciate the importance of omega-3 and omega-6 fatty acids: they are essential to obtain through foods since the body cannot itself make them.
Confusion about oils is partly from the postwar advertising efforts of the edible oil industry aimed to encourage us to shift from butter and other natural fats to their manufactured margarine and vegetable oils, as they tied cholesterol and saturated fats to chronic disease.link But another source of confusion stems simply from the multiple names that are used for oils. Flax oil, for example, is called an omega-3, for example, but it is also known as a super-unsaturated polyunsaturated fatty acid (PUFA) and as alpha-linolenic acid(ALA). Labeling categories for lipids include:
- Saturated and unsaturated: monounsaturated, polyunsaturated, super-unsaturated;
- omega labels: -3,-6,-9;
- oleic, linoleic (LA), and alpha-linolenic acids(ALA); and
- hydrogenated and partially-hydrogenated trans fats.
Oils are labeled to correspond to their physical makeup. The format of the diagrams in the box below is meant as a simplified way to outline a lipids structure, showing just the carbon atoms and the placement of the double bonds in each. (The table omits the hydrogen atoms and the methyl and carboxyl ends). A saturated fat like butter is a simple 4 carbon molecule, in contrast to fragile omega oils with 18 carbons and double bonds starting as early as the third carbon from the omega (methyl) end.
Lets clarify some labels.
Saturated versus Unsaturated. Fats with single bonds throughout are called saturated, while those with one or more double bonds are unsaturated. Saturated fats (fully saturated with hydrogens) are more stable since carbon and hydrogen atoms share electrons in lock-step, with each carbon linked to the next.
When a fatty acid is fully saturated, it interacts the least with other molecules in the body, and it provides the most stable structure. Saturated fats are helpful structurally because they help stabilize cell membranes, and they are not very susceptible to damage because they are primarily inert and noninteractive.link
Unsaturated oils are provide flexibility for cell membranes and are vital for intercellular communication but they are less stable since at a double bond, one pair of electrons is shared. Double bonds are vulnerable spots along an oil molecule that are subject to free-radical damage/oxidative stress. This is because an un-paired electron at a double bond invites free radicals wandering about the body and that are missing an electron to try to steal the single electron to form a new bond. Thus, unsaturated oils are more chemically active and reactive.
The Carbon Structure of Saturated and Unsaturated Fats and Oils
Buttersaturated. Butyric Acid (BA)the easiest to digest saturated fat.
C-C-C-C. (no double bonds)
Omega-9smonounsaturated. Oleic acid (OA).the most stable unsaturated oil.:
C-C-C-C-C-C-C-C-C==C-C-C-C-C-C-C-C-C (one @ 9th carbon)
Omega-6spolyunsaturated. Linoleic acid (LA)
C-C-C-C-C-C-C-C==C-C-C==C-C-C-C-C-C (two @ 6th & 9th)
Omega-3ssuper-unsaturated. Alpha linolenic acid (LNA)the most fragile unsaturated oil.
C-C-C-C-C-C-C==C-C-C==C-C-C==C-C-C (three, @ 3rd, 6th, 9th)
Oleic acid, linoleic acid (LA), and alpha-linoleic acid (ALA). Oleic means from oil. The names of oils get longer with the addition of more and more double bonds: oleic acid (omega-9), linoleic acid (omega-6), and alpha-linolenic acid (omega-3).
Why omega-3s and omega-6s are called essential fatty acids (EFAs). Plants and animals can use enzymes to insert double bonds into saturated fatty acid carbon chains in order to create unsaturated fats. Fats with multiple double bonds beginning at the 3rd omega position are vital to human life, particularly for electrical/cellular/neurological communication. In a fatty acid carbon molecule, plants are able to create double bonds as close as the 3rd and 6th carbon from the methyl (omega) end. In contrast, human enzymes can only create double bonds starting at the 7th carbon and beyond. Thus, plants supply us with omega-3 and omega-6 oils that are essential fatty acids (EFAs), vital building blocks for our health, that we cannot make ourselves. With plant-based omega-3s and -6s as raw materials, we use special enzymes to elongate and to desaturate these further, retooling them to serve a variety of critical sophisticated electrical functionsfor brain activity, cell regulation, and nerve impulses. [EPA and DHA, vital for brain function, are not called essential because they can be made by the body from ALAby healthy cells and with the proper co-factors: vitamins B3, B6, and C, and magnesium and zincsomething that cannot always be counted upon.]
Monounsaturated, polyunsaturated, and superunsaturated oils. Omega-3 oils are the most unsaturated plant-based EFA with double bonds that begin at the third position from the omega end and repeat after each set of three carbons. Thus, omega-3 fatty acids, with double bonds after the 3rd, 6th, and 9th carbons in its 18-carbon chain, are super-unsaturated and are the most flexible and the most vulnerable to oxidative damage of any of the unsaturated oils. Omega-6s have two double bonds after the 6th and 9th carbons and are called polyunsaturated oils. You may guess that omega-9s, like olive oil, are monounsaturated oils, with just one double bond after the 9th carbon.
The Reactive Nature of EFAs. The positions on omega-3 and -6 molecules at which double-bond occur are highly reactive, so they need to be used and stored with care (food manufactures often add BHA, and antioxidant, to prevent oxidative damage to packaged foods). With twice as much energy at double bonds than at other locations along the molecule,link these EFAs are the building blocks for sophisticated neurological/electrical functions in the body. The table below, which shows the multiple double bonds of fish oil is a clear indication of both its importance of neurological function and also its fragility.
Type of Fatty Acid
Key Fatty Acid
|Monounsaturated Omega-9||Oleic acid||18 carbons||1||Olive oil|
|Polyunsaturated Omega-6s||Linoleic acid||18 carbons||2||Safflower, sunflower, Sesame, and Gragpesee Oils|
|Gamma-linolenic acid||18 carbons||3||Borage, Evening Primrose Oils|
|Arachidonic acid||20 carbons||4||Beef fat, Egg Yolk|
|Polyunsaturated Omega-3s||Alpha-linolenic acid||18 carbons||3||Flax, Pumpkin, Hemp, Seeds and Walnuts|
|Eicosapentaenoic acid (EPA)||20 carbons||5||Fish oil|
|Docosahexaenoic acid (DHA)||22 carbons||6||Fish oil|
|Source: Adapted, Elson Haas|
The Proper Omega-6/Omega-3 Balance.
ourbalance of omega-6 to omega-3 affects our health as much as any other aspect of dietary fatBecause the ratio of omega-6s to omega-3s helps determine the flexibility of cell membranes, nearly all chemical communication throughout the body depends at least in part on the correct balance between omega-6s and omega-3s. Within this context, it is difficult to imagine any health problem that isnt partly related to the ratio of omega-6 to omega-3.link
Dominanceof Omega-6sVersus Omega-3s in a Variety of Cooking and Salad Oils
Ratio of Omega-6 to Omega-3 (Ideal is 3:1 to 1:1)
|Butter, Grass-fed animals||1:1|
Source: Pathways4Health, Derived from Mary Enigs Know Your Fats
Our forebears consumed a diet that was balanced with respect to omega-6 and omega-3 fatty acids, something around 1:1 to 3:1. But for todays typical American, this ratio stands at 20:1. Our modern diet of processed, convenience foods is one factor that explains this shift, since food companies rely upon refined, white vegetable oils like corn, soy, and cottonseedthey are cheap and have a long shelf life. Another factor behind this shift is that many modern households have grown to fear healthy saturated fats like butter and unrefined coconut oil and have switched to inexpensive vegetable oils, often believing that they are a healthier choice, and perhaps, too, because they have a long shelf life. Looking at the table above, which outlines the omega-6/omega-3 ratios of a variety of oils, it is easy to see how this ratio could soar to 20:1. Corn, safflower, and cottonseed oils are frequent ingredients in salad dressings and other prepared foods, and their omega-6/-3 ratios range from 72:1 for corn to 234:1 for cottonseed oil.
The Complexity of Fats and Oils
To understand fats also requires an understanding of their complexity: No fat is totally saturated. Neither is any natural fat entirely unsaturated. Fats are blends of saturated, monounsaturated, and polyunsaturated fats. For example, most people think of olive oil as a monounsaturated omega-9 oil. In reality, its fat composition is three-quarters monounsaturated omega-9s, with 8% polyunsaturated omega-6s, and a rather significant 16% share in the form of saturated fats (see Table 2).
The information in Table 2 that follows is important since the makeup of oils has a direct bearing on health. Not only do omega-3s, -6s, and -9s perform different functions in our body, but also the mix tells us a lot about how they can be best and most safely used, especially in cooking.
Complexity of Lipids and Implications for Cooking and Health
Saturated fats like butter and unrefined coconut oil are the most stable and the best choices for cooking. Olive oil, with only one double bond, can be used with care at low temperatures and for water sauteing (Table 2).
Omega-3 and omega-6 oils are fragile and should never be used in high-temperature cooking. This is especially true of omega-3 oils, which are five times more fragile than omega-6s. These oils need to be protected from light, oxygen, and heat, all of which damages them. They quickly go rancid.
Coconut (and palm kernel) oil is not only stable, but is also extremely rich in lauric acid, a potent antimicrobial. These two facts make unrefined coconut oil my first choice for cooking. (Chicken fat is also high in lauric acid, a key to why at the first sign of a cold, we reach for the chicken soup.) Note that butter also offers some anti-bacterial protection, with its modest share of lauric acid. The Table 2 also shows that nature provided antibacterial protection for young infants, with a generous lauric acid component in mothers milk.
Table 2: Composition of Nut and Seed Oils
(A Guide to Choosing Oils to Fight Inflammation)
Nut or Seed:
Source: Udo Eramus and Pathways4Health
Supermarket vegetable oils (corn, safflower, canola) bottled in clear glass are best left on the grocery store shelf. Refined oils do not promote health and should not be used in cooking. Processed in huge factories, these cheap oils have been damaged by light, oxygen, and heat. They are exposed to light and oxygen throughout the extraction process, as well as to toxic solvents like benzene. Heat used in extraction breaks apart the carbon bonds, setting loose free radicals. Oils are then deodorized at temperatures as high as 500 degrees to give them a pure appearance.link The result is white oils that are stripped of anti-oxidants and other nutrientssimilar to sugar and white flour, but with the added risks associated with free radical oxidative damage.
Frying at high temperatures does create a variety of toxic breakdown products but these are not the same as trans fats. Trans fats are created by a special chemical catalytic process (hydrogenation) that involves high temperature and pressure and the presence of limestone elements for filtration.link
The Cold-pressed label on standard vegetable oils has been abused.This label has not been regulated since the Federal government has never agreed on a definition for cold-pressed oils. Manufacturers have freely taken advantage of this. It is true that much of the extraction process with modern presses does not require the application of external heat (except to derive the last 10% of yield). But, extraction itself does involve heat that builds up from the normal friction and pressure of the pressing process (well above 200 degrees in large presses). Even if manufacturers can try to claim that their oils were pressed without heat, their advertising ignores the extreme heats used in the refining process, both before (the cooking stage prior to pressing, with average temperatures of 250 degrees) and after pressing (during the deodorizing process when oils are heated to close to 500 degrees for a period of six to eight hours.).link Look for the words unrefined on the label of all oils.
Every good fat and oil has its own strong points for health:
Butter is a short-chain triglyceride (SCT) saturated fatty acid that is very stable. Since it is digested and absorbed easily, it as a quick source of heat and energy (a good choice for the athlete and people who feel cold). It helps strengthen the immune system and has anti-microbial and anti-fungal properties. This is especially true of ghee (clarified butter), which is known for its healing powers. Butter from grass-fed animals is the best readily-available source of the fat-soluble vitamins A, D, E, and K, and carries these to the body in a form that is very easy to absorb and assimilate. These vitamins help with the absorption of a host of minerals that are vital for healthy bones and for the proper functioning of the nervous and reproductive systems. Buy organic, non-salted (this is how you know it is fresh) butter from grass-fed cows.
Unrefined coconut oil is a stable (it is 92% saturated) cholesterol-free oilsince it is a plant-based (plants have no liver to make cholesterol). Its high natural saturation, natures way of keeping coconut leaves stiff in tropical climates, adds to its value as a cooking oil in our own temperate environment. Unlike vegetable oils which are long-chain triglycerides (LCT), coconut oil is a medium-chain triglyceride (MCT). SCTs like butter and MCTs like coconut and palm kernel oil can be absorbed directly into the blood stream through the walls of the small intestine to be used as quick energy. In contrast, long-chain triglycerides (LCTs) like vegetable oils must first be converted to triglycerides in the intestine and then packaged for transport. LCTs, conveyed via chylomicrons, stay in the blood stream longer than SCTs and MCTs, to be deposited as fat when not needed. Because MCTs are utilized quickly much like carbohydrates, they help to boost metabolism while they also quickly satisfy hunger pangs. Some believe that coconut oil also contains fewer calories than any other fat.link Coconut oils bad name seems undeserved: it has antimicrobial powers and is the most cancer-reducing of all the fats.((Enig,81)) Be sure to purchase unrefined coconut oil that is free of hydrogenation.
Olive oil is a monounsaturated, omega-9 oil that can help lower cholesterol. It is liquid at room temperature and becomes cloudy when refrigerated. Its health benefits make it a good choice, particularly when it is used with foods that have already been cooked. Be sure to choose oil olive that is labeled Extra Virgin, First Cold Pressing (to assure chemical solvents and heat have not been used in the extraction process) and that is bottled in dark glass (to prevent oxidation). Keep in a cabinet when not in use to prevent free-radical damage.
Omega-6 oils are polyunsaturated oils that are too fragile for cooking, but that are vital to health (an EFA that the body must get through foods). They are especially important for proper functioning of the heart, liver, kidney, and reproductive organs, for hair and skin, for growth and behavior, and for the proper functioning of the immune system, as well as for wound healing (the inflammatory response). Omega-6 oils are fragile and are best used at the table, not for cooking.
Omega-3 oils, also EFAs, are super-unsaturated, with an extra double bond that makes them very fragile and reactive, never to be used in cooking, and yet vital to health in its own unique roles. Omega-3s are especially associated with proper brain function, mood and depression, behavior, vision, and motor coordination. They work on the opposite side of the spectrum when it comes to inflammation: they perform an anti-inflammatory role to give balance to a diet that includes pro-inflammatory omega-6 oils. Most experts believe an ideal ratio of omega-6s:omega-3 is somewhere between 3:1 and 1:1.
Three Simple Rules for Using Oils:link
- Use only unrefined oils. Refined oils are stripped of vital nutrients and antioxidants. All things that could make it taste rancid are removed so it cannot go rancid and you will have no clue as it is age. These are hidden in many prepared foods, including those that comply with FDA labeling requirements.
- Avoid hydrogenated and partially-hydrogenated oils. These are hidden in many unlabeled prepared foods.
- Choose only polyunsaturated oils that are pressed without exposure to light, heat, and oxygen.
Copyright 2010 Pathways4Health.org
- As Mary Enig points out, this idea was created in the 1950s to protect the margarine and shortening industries who were coming under attack by scientists who linked hydrogenation with heart disease. [link]
- Elson Haas, Staying Healthy With Nutrition, 65 [link]
- Haas,67 [link]
- Haas,68 [link]
- Edo Eramus, Fats that Heal, Fats that Kill, 96-7 [link]
- Enig, 279,271 [link]
- Eramus, 141-3 [link]
- Bruce Fife, The Fat that Can Make You Thin, Well-Being Journal, March/April, 2010, 20 [link]
- Paul Pitchford, speech to IIN, April, 2007 [link]