The Paleo diet:
Avoid vegetable and seed oils

Eating real food on the Paleo diet
will help you avoid vegetable and seed oils,
which are high in bad fat that are easily oxidized
and pro-inflammatory omega-6 fats.

The main oils used in processed food, at restaurants and even at home include soybean oil, canola oil, corn oil, peanut oil, cottonseed oil, safflower and sunflower oils, which are all high in easily oxidized polyunsaturated fats (PUFAs) and pro-inflammatory omega-6 fatty acids. (2)

Whereas olive and nut oil have been produced for thousands of years using presses, it is only in the last century that techniques were developed to use chemical solvents to extract oil from soy, canola, corn, peanut, cottonseed, safflower and sunflower. (1)

Margarines are made from the same processed oils and should also be avoided for the same reasons.  Shortenings are produced by hydrogenating these oils and are rich in harmful trans fat. (2)

Read food labels carefully to avoid foods containing any of these unhealthy vegetable or seed oils.

What’s wrong with
vegetable oils and seed oils?

Here are at least 2 BIG reasons to avoid them.

 1. Rancid and Oxidized

    Vegetable oils can easily be oxidized due to their high PUFA content. You can sometimes detect that an oil has gone rancid if it develops an unpleasant smell and taste, but some of these highly processed seed oils are deodorized to mask the oxidation that occurs during their processing.

    Oxidation is the result of the breakdown of the fatty acids found in the oils, which decreases its nutritional value and produces a lot of health-damaging and age-promoting free radicals. Free radicals can attack every cells of your body, contributing to systemic low-grade inflammation and the silent development of chronic diseases. (2)

 2. High Omega-6 to Omega-3 Ratio

    Both the omega-6 fat linoleic acid and the omega-3 fat alpha-linolenic acid are PUFAs recognized as essential for human health, but an imbalance between the two could compromise their functions. (2-4) Humans evolve eating about equal amounts of omega-6 and omega-3 fats, with a ratio of omega-6 to omega-3 close to 1:1. However, the increased consumption of omega-6-rich vegetable oils in the standard American diet has skewed this ratio up to between 15:1 and 20:1. (3)

    Omega-6 consumed in excessive amounts, as is the case with most processed foods made with seed oils, has a pro-inflammatory effect and may be involved in the development of numerous chronic diseases, such as cardiovascular diseases, some cancers, arthritis and other inflammatory and autoimmune conditions. (3)

    Learn about the omega-6 to omega-3 ratio on the Paleo diet.

You can find the omega-6 to omega-3 ratio of popular oils below:

Omega-6 to Omega-3 Ratio of Popular Oils


(g per cup)


(g per cup)


Canola oil*




Corn oil




Cottonseed oil




Grapeseed oil




Peanut oil



only omega-6

Safflower Oil Hi Linoleic




Safflower Oil Hi Oleic



only omega-6

Soybean oil




Sunflower oil Hi Linoleic



only omega-6

Sunflower oil Hi Oleic




* The ratio of canola oil does not appear to be too bad, but should be avoided because it is highly processed (with hexane as a solvent) and has a high content of easily oxidized PUFAs.** Calculated from reference (2)

Download the printer-friendly PDF version of the
"Omega-6 to Omega-3 Ratio of Popular Oils" table

More info from the Paleo dietitian:
The Paleo diet: 10 reasons why you should avoid grains.
No legumes (soy, peanut, beans or lentils) on the Paleo diet?
Healthy fats to include in your diet

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References:(1) Cordain L, et al. Origins and Evolution of the Western Diet: Health Implications for the 21st Century. Am J Clin Nutr. 2005; 81:341-54.(2) Enig ME. Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol. 2000.(3) Simopoulos AP. The Importance of the Ratio of Omega-6/Omega-3 Essential Fatty Acids. Biomedicine & Pharmacotherapy. 2002; 56(8): 365-79.(4) Carrera-Bastos P, et al. The Western Diet and Lifestyle and Diseases of Civilization. Research Reports in Clinical Cardiology. 2011; 2: 15-35.

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