This is not exhaustive, but intended to convey only the most important information as relating to the impact of oils on health, especially cooking oils.
Polyunsaturated fatty acids (PUFA):
PUFAs are easily oxidized by oxygen and heat, and form much higher amounts of toxic lipid peroxides than saturated or monounsaturated oils. These lipid peroxides cause oxidative damage, and their intake needs to be minimized. Some oils, such as canola and perilla, are high in alpha linolenic acid, which when heated, can lead to the formation of carcinogens and mutagens.
Oils high in PUFAs have to be manufactured, transported, and stored very carefully to be safe for eating. Ideally, PUFAs should be kept air-tight/oxygen-free and cold. PUFAs are not generally bad for you unless they are oxidized. All PUFAs that have been cooked with are oxidized and therefore bad.
PUFAs are considered damaged if at any stage in the manufacturing or transport and handling or use the oil has been exposed to excessive oxygen or heat. The same goes for nuts or seeds with a high PUFA content, although they are slightly more self-protected than naked oils.
Omega 3 and omega 6 oils are PUFAs. Many omega 3 oils have very beneficial effects, provided they are undamaged and handled very carefully, minimizing exposure to air and light and heat. For example, evening primrose oil is a commonly used supplement. Keep it in the fridge, and make sure it was not processed with heat.
Omega 6 oils are found abundantly in corn, soy, canola, sunflower, safflower and other commercially used cooking oils. The problem is that people are consuming too much of these oils, thus throwing off their omega 3 to omega 6 ratio. The proper balance is fats in a body is important, as if our fat balance is off, cell membranes and other cellular processes do not function quite as well. People today eat way too much omega 6 oils. The ideal ratio of omega 3 to omega 6 is about 1:4.
Part of the problem with commercial meats is that the animals are fed corn or soy, which not only are bad because they are GMO, but also bad because the ratio of omega 3 to omega 6 is imbalanced, and there is thus too much omega 6 and too little omega 3 in the resulting meat. People buying meat should look not only for organic, but also for free range.
Approximate PUFA content of various oils and fats:
Evening Primrose oil (81% PUFA)
Hemp oil (80% PUFA)
Flax oil (72% PUFA)
Grapeseed oil (71% PUFA)
Chia oil (70% PUFA)
Safflower oil (75% PUFA)
Sunflower oil (65% PUFA)
Perilla oil (63% PUFA)
Corn oil (59% PUFA)
Soybean oil (58% PUFA)
Pumpkin oil (57% PUFA)
Walnut oil (55-63% PUFA)
Cottonseed oil (50% PUFA)
Sesame oil (41-45% PUFA)
Canola oil (30-37% PUFA)
Rice bran oil (36% PUFA)
Beech nut oil (32% PUFA)
Peanut oil (29-32% PUFA)
Pecan oil (29% PUFA)
Brazil nut oil (24-36% PUFA, 24% SAFA)
Pistachio oil (19% PUFA)
Cashew oil (17% PUFA, 20% SAFA)
Almond oil (17% PUFA, 8% SAFA)
Duck fat (13% PUFA, 1% cholesterol)
Lard (12% PUFA, 41% SAFA, 1% cholesterol)
Filbert oil (10-16% PUFA)
Avocado oil (10% PUFA)
Macadamia oil (10% PUFA, 15% SAFA)
Goose fat (10% PUFA, 1% cholesterol)
Palm oil (8% PUFA, 50% SAFA)
Olive oil (8% PUFA, 14% SAFA)
Butter (4% PUFA, 50% SAFA)
Ghee (4% PUFA, 48% SAFA, 2% cholesterol)
Cocoa Butter (3% PUFA, 60% SAFA)
Coconut oil (2-3% PUFA, 92% SAFA, 0% cholesterol)
Palm kernel oil (2% PUFA, 82% SAFA)
Oils to Avoid:
Avoid food cooked in any oil over a 20% PUFA content: soy, canola, perilla, safflower, sunflower, corn, walnut oil, rice bran oil, and/or peanut oil. Ideally, choose oils that have a PUFA content of 10% or less for cooking. The higher the PUFA content of an oil, the more delicate it is, and the more carefully it should be handled. This means it needs to be kept airtight and refrigerated.
Canola oil is about 21% linoleic acid, and 7-10% alpha linolenic acid; and alpha-linolenic acid is an omega-3 PUFA which should NEVER be heated.
Avoid margarine and any oil that is hydrogenated, and any 'vegetable' oil. Do not use any oil that smells rancid. Most restaurants use vegetable oil, which is usually soy in North America. Other restaurants use canola oil, and this is more so in Canada. Avoid fried food if possible. Unfortunately, avoiding bad oils will probably mean not eating out except at very select restaurants that use good oils.
Oils to Cook With:
The best oils to cook with are the ones lowest in PUFA. But be aware that manufacturing and extraction processes can affect the quality of the oil. Always choose organic virgin grade oil if possible. Organic Virgin Coconut Oil is widely available, and is very reasonably priced.
Feel free to eat small to moderate amounts of raw organic nuts and seeds: cashews, pecans, filberts, macadamia nuts, almonds, walnuts, chia. Do not cook with any nut or seed with a high PUFA content. This is calculated by considering the percentage of PUFA in the oil, and the percentage of oil in the nut or seed. Avoid cooking with walnuts, sunflower seeds, sesame seeds, pumpkin seeds, chia, flax. Cashews, macadamia, filbert, almond, and pistachio can be cooked with if one must cook with nuts. Pecan and peanut are less ideal to cook with. People do cook with sesame seeds in small amounts, but remember that almost a quarter of the volume is PUFAs. About half the volume of a sunflower seed is PUFAs, and for walnuts it is just over a quarter.
Cook with virgin coconut oil, organic ghee, organic free range lard, free range goose or duck fat. Drizzle organic virgin olive oil over your food after it is done cooking, or if desired, sesame oil can be used for flavor. Other gourmet oils not mentioned can also be used in small amounts drizzled over food, but not for cooking unless low in PUFA. Coconut oil is good for stove-top cooking as well as baking. Almond oil, macadamia oil, virgin palm oil, and olive oil can be baked with but are less ideal for the stove-top. Walnut oil must NEVER be heated; treat it as delicately as flax oil.
Many poor quality commercial ghees have measurable amounts of trans fat, which could be due to adulteration with vegetable oils. But properly made quality ghee has been shown to decrease cholesterol levels and increase excretion of bile. Ghee can also lower prostaglandin levels and decrease secretion of leukotrienes, both of which are mediators of inflammation. Wistar rats fed native and oxidized ghee showed that a 10% ghee-supplemented diet decreased arachidonic acid levels in macrophage phospholipids. This being said, some people may experience higher triglyceride levels with ghee, so if you consume ghee, do so in moderation. It is important that ghee be organic, as non-organic butter and therefore non-organic ghee is high in PCBs.
Benefits of Healthy Oils:
Studies have shown that moderate (not high) fat diets can promote weight loss. Coconut oil has the added benefit of being high in medium chain fats that the body preferentially burns for energy instead of storing as fat. One to four teaspoons of good oil with each meal is very reasonable. Olive oil is high in monounsaturated fats, which are beneficial in small to moderate amounts. Avoid taking in any extra processed or heat damaged polyunsaturated fat as much as possible.
Good fats and oils are very important, as they are required for absorption of fat soluble vitamins. The cells in our body also require good fats in the cell membrane. We cannot live without fat.
Q and A:
Q: Is canola oil a good oil to use for cooking?
A: No, canola oil should not be used for cooking.
Q: Is it healthy to eat food or chips cooked in soy, canola, corn, safflower, sunflower or cottonseed oil?
A: No, it is not healthy.
Q: I love fries. What oils should they be cooked in?
A: Virgin coconut oil, grass fed ghee, and free range goose fat would be preferred, but keep the heat as low as possible. Ghee has the highest smoke point.
Q: Walnut oil has a high smoke point. Should I use it for cooking?
A: No, walnut oil should not be cooked with but can be drizzled on food after cooking.
Q: What is the best all-purpose oil for use in stove top cooking and in baking?
A: The best all-purpose oil for cooking and baking is organic virgin coconut oil.
Q: What oils are good for baking with?
A: Oils good for baking are virgin coconut oil, virgin palm oil, olive oil, macadamia oil, almond oil, and organic ghee.
Q: Where can I get virgin coconut or palm oil?
A: Virgin coconut oil is now widely available at most grocery stores. Virgin palm oil is harder to find, but can be found online.
Licorice and Garlic Mixed Nuts
Warning..may be addicting.. Use organic if available.
10-14 oz raw nuts of your choice
Sea salt, Real Salt or Himalayan salt, fine ground
licorice root powder
1 tbsp coconut oil
Heat a tablespoon or so of virgin coconut oil in a pan just enough to liquify it. Turn off the heat.
Add your choice of organic raw mixed nuts, mixing well with the coconut oil to coat all the nuts.
Put in a glass storage container in layers, stopping between layers to sprinkle with garlic powder, fine salt, and licorice powder.
Enjoy and / or cover when cool.
This nut mix has been well received at parties and with co-workers, and is a great traveling food. Do not attempt to be exact.. I have never measured anything in this or any other recipe. Just use your best judgement. If you like the result, then you have done it correctly. You can get licorice root powder from online retailers like iherb.com or Mountain Rose herbs.
Su Fairchild, MD
Copyright 02/21/2012, revised 02/27/2012
This page may be freely linked to or reproduced only in its entirety with proper acknowledgements.
Acknowledgement and thanks to Diana Noland RD, who shared knowledge with me.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3215354/ "The effect of ghee (clarified butter) on serum lipid levels and microsomal lipid peroxidation"