The Skinny on Fats, Part 2 - Part 1 can be found on the previous blog entry.

Polyunsaturated Fatty Acids: Due to the chemical nature of polyunsaturated fatty acids, they are very loosely packed, they remain in a liquid state, and are highly unstable when exposed to heat and light. Therefore, these oils should be packaged in dark glass and stored away from heat (though most are not). The unstable nature of polyunsaturated fatty acids makes them susceptible to the formation of free radicals. Free radicals are highly reactive molecules that can cause inflammation and tissue damage. They have been implicated in a number of diseases.

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 the body cannot make them and they must be obtained through the diet. Examples of foods high in omega-6 fatty acids include safflower, sunflower, soybean, grapeseed, corn, canola and cottonseed oils.

Examples of foods high in omega-3 fatty acids include cold-water fish (salmon and mackerel), grass-fed beef, flaxseed, and walnuts. Some sources say that humans evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids of approximately 1:1. The modern Western diet typically has a ratio of ~15:1. It is generally deficient in omega-3 fatty acids, and has excessive amounts of omega-6 fatty acids compared to the ancestral diet, on which genetic patterns were established.
Excessive intake of omega-6 fatty acids and a very high omega-6:omega-3 ratio have been shown to promote the many diseases, including cardiovascular disease, cancer, inflammatory and autoimmune diseases. Increased levels of omega-3 fatty acids (a low omega-6:omega-3 ratio) has been shown to exert favorable effects on cardiovascular disease, certain cancers, inflammation and asthma. Following a diet with a lower ratio of omega-6:omega-3 fatty acids is more desirable in reducing the risk of many of the chronic inflammatory diseases that are highly prevalent in Western societies.

A Word on Medium Chain Triglycerides (MCTs): Oils can contain short chain, medium chain, or long chain fatty acids. Dietary sources of MCTs include palm kernel oil and coconut oil. MCTs have been shown to increase fat oxidation and energy expenditure as well as reduce food intake and beneficially alter body composition. The research is mixed regarding the use of MCTs for improving exercise performance.

MCT oil is used by some to help promote a ketogenic state, which has clinical applications for neurodegenerative disorders such as seizures, Parkinson’s and Alzheimer’s disease.

Trans Fats and Hydrogenated Oils: Hydrogenation is an artificial process whereby polyunsaturated fatty acids, which are normally liquid at room temperature, are converted into solid fats at room temperature. The most common example is the conversion of vegetable oils into margarine and shortening.

Margarine was once thought to be a heart-healthy alternative to saturated fats, but trans fats have been linked to a number of adverse health conditions. The polyunsaturated fatty acids in most vegetable oils are inherently unstable and can lead to the formation of free radicals. Hydrogenated vegetable oils are even worse as the process of hydrogenation changes the natural configuration of these hydrogen atoms, “cis,” to a formation called “trans.”

The “trans” formation can cause serious problems in cell metabolism, including depression of the immune system, cardiovascular disease, diabetes, obesity, sterility, birth defects, decreased ability to produce breast milk, loss of vision, and weakening of bones and muscles.

It’s hard to believe that trans fat-laden margarine was once promoted as a health food and used to replace the naturally occurring saturated fat that humans have been consuming since Paleolithic times. Common sources of trans fats other than margarine include shortening, deep fried foods (e.g., doughnuts, french fries, fried chicken, etc.), and commercially baked goods, such as cookies, crackers, and pastries. Trans fat may also be lurking in non-dairy creamers, microwave popcorn and other packaged snack and ready-made items.

What About Cholesterol? Cholesterol comes from animal sources and is made in the liver. It is essential for a long list of functions; cell membrane integrity, stress and reproductive hormones, vitamin D production, a healthy nervous system, proper immune system function, bile production needed for digestion of fat in our foods, protecting us against cellular damage that leads to heart disease and cancer, maintaining a healthy intestinal lining, protecting against autoimmune diseases, and anti-oxidative activity
We’ve been told for decades to limit cholesterol-rich foods, but in light of current research, that advice may be changing.

In fact, the American Heart Association changed its policy on dietary cholesterol in 2013, citing insufficient evidence to support the idea that eating a lot of cholesterol in foods leads directly to higher amounts of artery-clogging cholesterol in the bloodstream.

Exercise & Excess Post-Exercise Oxygen Consumption (EPOC): High-intensity interval training results in EPOC, causing an increased rate of triglyceride/fatty acid cycling and a shift from carbohydrate to fat as a fuel source. EPOC has been shown to be a good strategy for fat loss and conditioning.

Practical Eating Tips

    1    Cook with extra virgin coconut oil, organic (preferably grass-fed) butter, extra virgin olive oil, or avocado oil.
    2    Each oil has a different smoke point based on its chemical structure. Be sure not to heat an oil beyond its smoke point as this leads to free radical formation.
    3    Avoid polyunsaturated vegetable oils: safflower, corn, sunflower, soybean and cottonseed. These are unstable and pro-inflammatory. If you use canola oil, make sure it’s organic (otherwise it will be genetically modified).
    4    Avoid deep fried foods, unless they have been deep fried in a good quality oil (virgin coconut oil, red palm oil or avocado oil) that has not been re-used.
    5    Avoid anything that is made with hydrogenated or partially hydrogenated oils. This includes shortening and margarine, french fries, onion rings, tempura, doughnuts, and most processed, commercially prepared baked foods like, crackers, potato chips, cookies, chocolate bars, muffins, cakes, and pastries.
    6    Avoid nuts and seeds roasted in oil as these are usually polyunsaturated oils. You’re better off roasting them yourself.
    7    Eat healthy, concentrated sources of fat from plant foods, including avocado, raw nuts, raw seeds, unsweetened coconut, coconut milk, virgin coconut oil, and extra virgin olive oil.
    8    If consuming fat from animal sources, choose organic eggs from free-range birds, cold-water fish, organic chicken, grass-fed butter and red meat (beef, buffalo, and lamb), and wild game.

References
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