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Understanding Fats and Oils

Before the 1920s, heart disease was extremely rare in North America and other developed countries. When a young internist at Harvard University named Paul Dudley showed a German heart monitor to his fellow doctors, he was told that he best put his energy into a more profitable area of health care. This heart monitor, also known as an electrocardiogram, was able to detect blockages in the arteries that supply the heart. The problem was that heart disease was so rare that he struggled to find people who would benefit from his machine.

From the 1920s to the 1950s, the incidence of coronary artery disease rose dramatically, becoming the leading cause of death for Americans. Today, it is estimated that 40 percent of all deaths in America are caused by heart disease.

Would you be surprised to know that during the time that heart disease climbed to its present level, consumption of animal fat in the United States decreased approximately 25 percent? Also, from 1910 to 1970, the average person decreased her intake of butter from 18 pounds per year to 4.

Here are three more statistics from the past eight decades in America:

  • Cholesterol obtained from food has increased 1 percent
  • Consumption of refined vegetable oils, margarine, and shortening has increased 400 percent
  • Consumption of sugar and processed foods has increased approximately 60 percent

Clearly, this information is not congruent with the present day theory that heart disease is caused by saturated fat and cholesterol. In order to sort through the misinformation and myths surrounding fat consumption and human health, we first need to understand the biochemistry of fat.

Biochemistry 101
Fat that is found in our food is composed mainly of fatty acids. Fatty acids are classified into three major groups: saturated, monounsaturated, and polyunsaturated.

All fatty acids are made up of a chain of carbon atoms with hydrogen atoms filling in the spaces around each carbon atom.

Saturated Fatty Acids
When the spaces surrounding each carbon atom are completely filled, or saturated with hydrogen atoms, you have a saturated fatty acid. Because each carbon atom is completely surrounded by hydrogen atoms, saturated fatty acids are compact in structure, making them extremely stable, even under high temperatures. Saturated fatty acids are found mainly in animal fats like dairy, red meat, and chicken, as well as in tropical oils like coconut and red palm oil. Your body makes some of its saturated fatty acids from carbohydrates in your diet.

Monounsaturated Fatty Acids
When a fatty acid is missing two hydrogen atoms, it has a double bond between two of its carbon atoms. We call this type of fatty acid a monounsaturated fatty acid, mono, because there is only one double bond, and unsaturated because the two carbons atoms that share a double bond are not saturated with hydrogen atoms. The double bond of monounsaturated fatty acids causes the entire chain of carbon atoms to bend at the double bond, which means that many of these chains mixed together will not form a densely packed, compact structure. Because of this, monounsaturated fatty acids are usually liquid at room temperature. Having only one kink in each chain of fatty acids translates to monounsaturated fatty acids being relatively stable, even when exposed to some heat. Of course, they cannot be as stable as saturated fatty acids, which are as tightly packed as possible. The most common type of monounsaturated fatty acid found in food is called oleic acid. Monounsaturated fatty acids are found in olive oil, avocados, peanuts, almonds, pecans, and cashews. Your body can also make monounsaturated fatty acids out of saturated fatty acids.

Polyunsaturated Fatty Acids
When a fatty acid chain is missing several hydrogen atoms, it has two or more double bonds. These fatty acids are called polyunsaturated fatty acids, poly, because there is more than one double bond. Because each double bond represents a kink in the fatty acid chain, polyunsaturated fatty acids have two or more kinks, and are therefore very loosely packed, and remain liquid even in the refrigerator. They are highly unstable, and go bad quite easily when exposed to heat and light. When polyunsaturated fatty acids go bad, free radicals are created. Free radicals are compounds that travel around in your blood, causing damage to just about everything that they come into contact with. Consistent exposure to free radicals has been strongly linked to the development of tumors, cardiovascular disease, premature aging, autoimmune diseases, Parkinson’s disease, Alzheimer’s, and cataracts.

The most common polyunsaturated fatty acids found in our foods are omega-6 and omega-3 fatty acids. These fatty acids are considered to be essential fatty acids, because your body cannot make them. They must be obtained through your diet.

To summarize the biochemistry of fatty acids, there are three main types of fatty acids; saturated, monounsaturated, and polyunsaturated. Saturated fatty acids are extremely stable, even at high temperatures, and polyunsaturated fatty acids become harmful to human health when exposed to heat because of free radical formation.

Getting Back to Food
What’s interesting is that all fats and oils from animal and plant sources are made up of a combination of all three types of fatty acids. In general, animal fats such as butter and fat found in beef and chicken have around 40-60 percent saturated fatty acids. Because of their high content of saturated fatty acids, animal fats tend to be solid at room temperature. Vegetable oils from low temperature climates tend to have a higher percentage of polyunsaturated fatty acids, and are therefore liquid at room temperatures. But vegetable oils from warmer climates, like coconut oil and red palm oil, have high percentages of saturated fats. This is because saturated fats impart necessary stiffness to the leaves of plants in tropical climates.

Cooked animal fat found in grass-fed red meat (beef, buffalo, and lamb), organic chicken, wild game, cold-water fish, and organic eggs and cooked tropical oils can still be healthy food choices because their high concentrations of saturated fatty acids are not damaged with exposure to heat. However, the small amounts of polyunsaturated fatty acids in these foods become harmful once exposed to heat. This is the primary reason why I believe there is some merit to the idea of eating raw, organic animal foods for health. It’s hard to say how much harm is caused by the damaged polyunsaturated fatty acids in cooked animal foods, given that they are a minor component in these foods. But the fact that cooked animal foods contain some harmful free radicals that are formed when the polyunsaturated fatty acids in animal foods are heated is unquestionable. Also, it is important to take into account the farming practices behind the animal foods that you choose to eat. Factory farming and non-organic environments increase the likelihood of proliferation of harmful microorganisms, making the use of heat more appealing, despite the creation of some free radicals. The bottom line is this: if you are able locate and afford organic animal products, I believe that they are most healthful when eaten raw or cooked at low to medium temperatures. Not conventional nutritional advice, I know, but my experiences and studies support this viewpoint.

The Key Ratio
Getting back to polyunsaturated fatty acids, one of the essential keys to excellent health is to maintain a good balance between the two most common polyunsaturated fatty acids – omega-6 and omega-3. An optimal ratio is about 1:1. Vegetable oils like safflower, corn, sunflower, soybean, and cottonseed all contain at least 50 percent omega-6 polyunsaturated fatty acids, and very little amounts of omega-3 polyunsaturated fatty acids, putting their omega-6 to omega-3 ratios as high as 20:1. Also, factory farming practices significantly decrease the omega-3 content of meat, fish, eggs, and vegetables, contributing to a high omega-6 to omega-3 ratio. This is another argument for the use of organic foods if possible.

Why is this ratio so critical to your health? If you have too much omega-6 compared to omega-3, you will have imbalances at a cellular level that will contribute to generalized inflammation, high blood pressure, digestive passageway disturbances, depressed immune function, sterility, weight gain, increased tendency to form blood clots, and even cancer. Please do not underestimate this facet of your health!

What can you do to ensure that your body has a good ratio of omega-6 to omega-3 fatty acids? Some private labs offer an expensive blood test that analyzes your fatty acid profile. If you're like me and prefer not to have blood drawn unless absolutely necessary, you can strive to maintain a healthy ratio by eating a well balanced diet of whole, relatively unprocessed foods. For many people, eating a diet that is abudant in vegetables with smaller amounts of fruits, legumes, nuts, seeds, whole grains, and organic or wild animal products including cold-water fish will very likely result in a healthy ratio of omega-6 to omega-3. If you prefer not to use animal products, or are unable to locate organic or wild sources of animal products, I recommend that you consider using a high quality cod liver oil. Cod liver oil has an abundance of omega-3 fatty acids, particularly the longer chain omega-3 fatty acids, DHA and EPA. Without supplementation, it is extremely difficult for strict vegans to obtain adequate quantities of DHA from only plant sources of omega-3 fatty acids like flax seeds and walnuts. This nutrient is particularly important for those with cardiovascular disease, any condition that is accompanied by chronic inflammation, and women of child-bearing status, as DHA is critical for proper development of the nervous system.

An important note about cod liver oil: it is important to take the appropriate amount for your physiology. If you use the one that my family uses, from Carlson Labs (, a safe dosage is approximately one teaspoon per 50 pounds of body weight, per day. The only exception to this guideline is if you are already getting plenty of vitamin D from your diet and through sun exposure. Overdosing on vitamin D can cause serious health challenges, so please do your research before beginning supplementation with cod liver oil. For more guidance in this area, please feel free to contact me or visit

Cooking With Oil
If you must cook with vegetable oils other than coconut or red palm, the order of preference is olive, peanut, and sesame. These three oils have the highest percentages of oleic fatty acid, the relatively stable monounsaturated fatty acid. Although canola oil also contains a large percentage of monounsaturated fatty acids, it should be avoided because it has a high sulfur content and goes bad very easily. Canola oil is highly susceptible to developing trans fatty acids during processing, making it similar to margarine and shortening.

Trans Fats and Hydrogenated Oils
Speaking of trans fatty acids, where do they and hydrogenated oils fit into the picture?

Hydrogenation is a process that converts polyunsaturated fatty acids – which are normally liquid at room temperature – into solid fats at room temperature. The most common example is the conversion of vegetable oils into margarine and shortening. In case you're curious, this is done because hydrogenated vegetable oils don't go bad nearly as quickly as regular vegetable oils do, prolonging the shelf life of whatever product they are in.

Let’s remember that the large concentration of polyunsaturated fatty acids in most vegetable oils are harmful to begin with, as their inherent instability leads to formation of free radicals. Hydrogenated vegetable oils are even worse. This is because the process of hydrogenation changes the configuration of hydrogen atoms in polyunsaturated fatty acids to a formation called “trans”. The normal configuration of these hydrogen atoms is called “cis”, and almost all polyunsaturated fatty acids found in nature are of the “cis” configuration.

The trans formation is a huge problem for your tissues, as trans fatty acids are incorporated into your cell membranes and cause serious problems in cell metabolism. More specifically, trans fats are known to cause immune system depression, cardiovascular disease, diabetes, obesity, sterility, birth defects, decreased ability to produce breast milk, loss of vision, and weakening of your bones and muscles. Can you believe that margarine, loaded with its trans fatty acids, is promoted as a health food?

So now you know that trans fats come mainly from oils that have been hydrogenated. The most concentrated sources of trans fats in the North American diet are margarine, shortening, French fries, fried chicken, doughnuts, cookies, crackers, and pastries. To give you some numbers, French fries typically have 40 percent trans fatty acids, while many popular cookies have anywhere from 30 to 50 percent trans fatty acids. Not to be forgotten, doughnuts usually have between 35 to 40 percent trans fatty acids. This is why I like to say that French fries and doughnuts are two of the worse foods for your health, with soda rounding out the toxic trio. The only reason why commercial cookies don’t make the list is that there is such a wide variety of cookies, and I don’t want to tag all of them as being extremely harmful.

What About Cholesterol?
No discussion about fat consumption and human health would be complete without mention of cholesterol. You get cholesterol from animal foods as well as from your liver, which makes it from other nutrients. As outlined in a previous newsletter, cholesterol is needed to:

  • contribute to cell membrane rigidity and strength
  • make hormones that help us deal with stress, as well to make sex hormones
  • make vitamin D, essential for proper growth, healthy bones, a healthy nervous system, muscle tone, and proper immune system function
  • make bile, needed for digestion of fat in our foods
  • act as an antioxidant, protecting us against cellular damage that leads to heart disease and cancer
  • maintain a healthy intestinal lining, offering protection against autoimmune illnesses

Perhaps the most under publicized property of cholesterol is its anti-oxidative ability. Cholesterol is an extremely effective anti-oxidant that protects you against the effects of free radicals.

Cholesterol is used to repair damage in your blood vessels. Usually, high blood cholesterol levels are an indication that your body is in need of extra anti-oxidative help from cholesterol to deal with harmful fats and free radicals. As Sally Fallon puts it, “just as a large police force is needed in a locality where crime occurs frequently, so cholesterol is needed in a poorly nourished body to protect the individual from a tendency to heart disease and cancer. Blaming coronary heart disease on cholesterol is like blaming the police for murder and theft in a high crime area.”

Of course, cholesterol can be harmful to your body if it has been damaged by exposure to heat and oxygen. Cholesterol that has been damaged can cause direct injury to blood vessel walls, leading to a build-up of unwanted plaque. This is another argument for using organic animal products that do not necessitate exposure to high heat.

To summarize, here are ten practical tips on healthy vs. unhealthy fats:

1. The very best oil for you to cook with is virgin coconut oil.

2. Olive, peanut, and sesame oil can withstand some exposure to heat without becoming harmful, but it is best to avoid using these oils for cooking on a regular basis. Olive oil is best eaten raw or added to your food after it is off the stove.

3. Avoid the following polyunsaturated vegetable oils: safflower, corn, sunflower, soybean, cottonseed and canola.

4. Never eat margarine or shortening and foods that contain them.

5. For people who can tolerate butter, it is important to use organic butter. Try to find butter that has a rich, dark yellow color, representing great nutritional density.

6. Avoid all deep fried foods, unless they have been deep fried in virgin coconut oil or red palm oil. You can safely bet that very few restaurants in Canada or the States use these two tropical oils to deep fry. Also, unless you used red palm oil when you were growing up, you are likely to find it objectionable.

7. Avoid anything that is made with hydrogenated or partially hydrogenated oils. This includes French fries, onion rings, tempura, doughnuts, and most processed, commercially prepared baked foods like, crackers, potato chips, cookies, chocolate bars, muffins, cakes, and pastries.

8. Avoid nuts and seeds roasted in oil.

9. Excellent, concentrated sources of fat from plant foods include: avocado, raw nuts, raw seeds, unsweetened coconut, coconut milk, virgin coconut oil, and raw olive oil.* Most people should limit their intake of raw nuts and seeds to approximately one to two handfuls per day.

10. Excellent, concentrated sources of fat from animal foods include: cod liver oil, organic eggs from free-range birds, cold-water fish, organic chicken, grass-fed red meat(beef, buffalo, and lamb), and wild game.*

*As with all of the foods that you eat, it is important to observe your body’s feedback in order to determine which healthy foods are in fact healthy for your unique biochemistry.


1. Enig, Mary G, PhD, Trans Fatty Acids in the Food Supply: A Comprehensive Report Covering 60 Years of Research, 2nd Edition, Enig Associates, Inc., Silver Spring, MD, 1995, 4-8

2. Enig, Mary G, PhD, Know your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils, and Cholesterol, Bethesda Press, May 14, 2000

3. Fallon, Sally, M.A., Nourishing Traditions – The Cookbook that Challenges Politically Correct Nutrition and the Diet Dictocrats, New Trends Publishing, 1999


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Dear Dr. Kim
Wondering your thoughts on the healthfulness of cooking with beef tallow, duck fat, rendered leaf lard, chicken schmaltz, etc. (all from organic, pastured sources, of course). Are these approximately equal to, or inferior to virgin coconut oil? Thanks, as always, for your insights.

Hi Nicole,

I think all are fine to use with the understanding that lower cooking temperatures are best.