Fatty Acid Content of Refined Vegetable Oils

Vegetable oils were obviously not a component of any pre-agricultural or hunter gatherer diet, simply because the technology to produce them did not exist.  Oils made from walnuts, almonds, olives, sesame seeds and flax seeds were first produced using crude presses between 5,000 and 6,000 years ago.  However, except for olive oil, most early use of oils was for non-food purposes such as illumination, lubrication and medicine.  It wasnât until the beginning of the 20th century with the advent of mechanically driven steel expellers and hexane extraction processes did vegetable oils contribute significantly to the energy intake of the western diet.  Today vegetable oils used in cooking, salad oils, margarine, shortening and processed foods supply 17.6 % of the total daily energy intake in the U.S. diet.  The enormous infusion of vegetable oils into the western diet starting in the early 1900âs represents the greatest single factor responsible for elevating the dietary omega 6 to omega 3 ratio to its current and unhealthful value of 10.  In hunter gatherer diets the omega 6/omega 3 ratio was closer to 2.  

So if this is the case, then why should you not eliminate all vegetable oils from your diet?  Simply stated, there are at least five oils (flaxseed, canola, walnut, olive, and avocado) that can promote health and facilitate getting the correct balance of good fats in your diet.  Because hunter gatherers ate the entire carcass of wild animals (tongue, eyes, brains, marrow, liver, gonads, intestines, kidneys, etc.) and relished fatty plant foods (nuts and seeds) they did not have to worry about the correct balance of fatty acids in their diet.  It came out correctly in the wash.  For most of us the thought of eating organs is not only repulsive, but is also not practical as we simply do not have access to wild game.   Consequently, by eating lean meats, fish and seafood along with healthful oils, nuts and seeds, you can get the correct balance of fatty acids in your diet. 

As you can see from the tables listed below, only three vegetable oils have omega 6/omega 3 ratios of less than 3.  These are flaxseed oil (0.24), canola (2.2) and mustard seed (2.6).  Although I originally recommended mustard seed oil in the first edition of The Paleo Diet, I can no longer make this recommendation because of its high erucic acid (22:1) concentration of 41.2 %.  High dietary intake of erucic acid in laboratory animals has been shown to cause deleterious changes in heart structure and function.  Human studies in India show that mustard seed oil consumption counters the heart healthy effects of its high concentration of omega 3 fatty acids.

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Hence, this leaves only two vegetable oils (canola and flaxseed) that do not contribute to an elevated intake of omega 6 fatty acids.  Recently, a number of epidemiologic studies have shown a higher risk for prostate cancer with increased consumption of alpha linolenic acid (ALA), a major component of both canola and flaxseed oil.

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In contrast, the consumption of longer chain omega 3 fatty acids (EPA + DHA) found in fish and fish oil capsules actually decreases the risk for prostate cancer.   Further, not all studies have demonstrated a statistical link between ALA and prostate cancer.

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In support of this notion, are animal experiments showing that whole flaxseed actually inhibits the growth and development of prostate cancer.

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The case against flaxseed and canola oil as promoters of prostate cancer is currently based solely upon epidemiologic evidence and therefore remains inconclusive because of the total lack of confirming experimental evidence.  Because the majority of epidemiological studies support the notion that ALA is protective against cardiovascular disease, both canola and flaxseed oils should still be viewed as healthful.

Both olive oil and avocado oil are high (73.9 and 70.6 % respectively) in cholesterol lowering monounsaturated fatty acids, but have less than favorable omega 6/omega 3 ratios of 11.7 and 13.5.  Consequently, excessive consumption of both of these oils without adequate intake of long chain omega 3 fatty acids (EPA + DHA) will derail an otherwise healthy diet.   We recommend that you get 0.5-1.8 grams of EPA + DHA per day in your diet from either fish or fish oil capsules (see additional information about omega 3 and fish).

In the following tables we list the fatty acid content of most commercially available vegetable oils.  You can use these tables to help you make an informed decision in choosing your vegetable oil based upon its fatty acid composition.  If you are unfamiliar with fatty acid nomenclature and how the different types of fatty acids impact your health please refer to our fatty acid primer.

Please click here to read an article about peanut oil and cardiovascular disease.

Table of Vegetable Oils: linoleic acid, caproic acid, etc.

Click to view a comprehensive Table of Vegetable Oils - linoleic acid, oleic acid ...