The Skinny on Fats, Part IIby Laura J Hieb, ND on December 21, 2021
The Skinny on Fats Part II
Fats can be categorized as being saturated, monounsaturated and polyunsaturated.
Saturated fats make up most of the fats in traditional diets, and did so in the US diet until the 1950's when president Eisenhower suffered a heart attack and the (in)famous Ancel Keys published his (flawed) research on saturated fats causing heart disease. Since then, Americans were told to avoid saturated fats and switch to unsaturated fats, so now unsaturated fats make up the bulk of most people's fat intake.
First of all, what makes a fat a saturated fat?
Fats are chains of carbon atoms. If there is a hydrogen atom at every available site on the carbon atom it is a saturated fat since all the carbon atoms are "saturated" with hydrogen atoms. Saturated fats are very stable and not easily oxidized, so they don't tend to create the afore-mentioned free radicals. They can be used to cook at higher heats .Saturated fats include all animal fats. Coconut and palm oils are also mostly saturated fats. Saturated fats remain solid at room temperature, like butter and coconut oil. Hydrogenated oils like shortening are also solid at room temperature, but that is because of the hydrogenation process that creates the bad trans fats.
Saturated fats are important because we make cholesterol from them and cholesterol is necessary for life. Let me repeat that.
Cholesterol is necessary for life.
That is why our body makes it. We need it for our cell membranes and to make our reproductive (sex) hormones and our adrenal hormones, vitamin D (also a hormone) and some of our digestive enzymes, such as lipases.
Getting cholesterol from our diet saves the body from having to make it all on its own. If you eat animal protein, you are getting good cholesterol sources. If you are vegan, it is important to eat some form of coconut on a regular basis. Please note: eating cholesterol-rich foods does not elevate your cholesterol levels. Sugar does.
Fats that are not "saturated" with hydrogen are known as unsaturated oils. Monounsaturated oils contain one "double bond" wherein 2 carbon atoms bind to each other at one site in the chain, so they are mono- (one bond) unsaturated. They are stable enough to be used for low-to-moderate heat cooking. Avocado oil may be stable enough to use for high heat cooking, according to some sources.
Examples of mono-unsaturated fats include olive oil, avocado oil, peanut oil and canola oil. As you notice, the last 2 are listed under the "bad" oils.
- Peanut oil is a traditional food, but recently most peanut crops have been contaminated with a mold containing aflatoxin, which has been associated with cancer. There is some controversy about this.
- Canola oil is a new oil, genetically hybridized from rapeseed oil to minimize the erucic acid content which has been considered not so good for human health. Some canola oil is solvent-extracted and definitely should be avoided. Expeller-pressed canola oil is definitely cleaner. Canola oil is highly refined, which eliminates most of the health-giving polyphenols which are typically found in olive oil. The polyphenols in olive oil are what cause it to solidify at temperatures less than 45 degrees F, so canola oil is often used in refrigerated deli foods, because is stays mostly liquid at cold temps. Canola oil is higher in the good omega-3 essential fatty acids than olive oil, but this makes it more unstable than olive oil, meaning it may oxidize/ go rancid more easily. To deal with this instability, some canola oil manufacturers partially hydrogenate it (yikes!). To put it mildly, there is a lot of controversy about canola oil.
Lastly we get to the polyunsaturated oils.
Polyunsaturated means there are more than 1 double bond (where a carbon atom binds to another carbon atom) in a chain of carbon atoms. Polyunsaturated oils are highly unstable, meaning they oxidize/go rancid easily and are very heat sensitive. They should be stored in the fridge and they should never be heated! (Avoid the potato chips deep fried in cotton seed and safflower and sunflower oils, etc.) Examples of polyunsaturated oils include the above 3, all other seed oils (soy, corn, grapeseed, hempseed oil, flaxseed oil) and fish oil.
Obviously not all are bad. Hempseed oil, flax seed oil and fish oils are all good sources of omega-3 essential fatty acids. Essential means our bodies cannot make them--we must get them from our diet. Omega-3 fatty acids are anti-inflammatory, which is a good thing. The other polyunsaturated oils are high in the pro-inflammatory omega- 6 oils. While omega-6 oils are also essential, they are more abundant in our diets than omega-3 oils, which means we are more prone to inflammation. Omega-3 and omega-6 essential fatty acids (EFA's) should be at a 1-1 ratio for optimal health.
More on fats and weight gain and loss coming up.