dietpoison

All fats are subject to oxidation.  Because of this we have terms that tell how quickly a fat can become oxidized: (a) saturated fats are stable chemically and are the least likely to oxidize; (b) unsaturated fats are chemically unstable and are the most likely to oxidize.  Further, unsaturated fats can be categorized into monounsaturates (only one double bond that can be oxidized) and polyunsaturates (more than one double bond that can be oxidized).

Avoid large amounts of polyunsaturates in your diet;  74% of all fatty acids in atheroma blockages are these dangerous and unstable unsaturated fatty acids.

And so by definition we must be very suspicious of any polyunsaturates, or to be more accurate, we must be very aware of how these deadly polyunsaturates have been treated in processing, before we eat them.

Of course, we need polyunsaturates in our diet (especially the omega-3 variety), but we should look at the healthy form they take in nature.  Let’s take seeds and nuts as an example.  Seeds and nuts have a dark-colored skin, to keep sunlight from oxidizing the fats.  Seeds and nuts also contain a dose of healthy antioxidants to protect the fats from oxidation.

Tragically, the crystal clear vegetable oil you buy at the store is expeller pressed from the seeds and nuts, and then the remaining oil is removed using industrial solvents like hexane.  Then the oil is bleached and clarified so that it’s sparkling and attractive, and the sum of these processes removes all the antioxidants and synergists from the oil.

The best thing you can do of course is to get these fats from the whole foods that contain them, since you get the full benefit of antioxidants, vitamins, and other healthy compounds.  However, if you must purchase and use vegetable oils, then, follow these simple rules:

1. Purchase Cold-Pressed Oils.  These are more expensive because it’s not possible to extract as much oil using this method.
2. Avoid Light.  Purchase only oils that you find in dark containers (that don’t let in the light), the darker the better. Store them in a cool dark place.
3. Avoid Heat! Don’t overheat polyunsaturated fats.  In particular, don’t cook with fats that are polyunsaturated, as it increases oxidation of these fats.  You should be cooking with saturated fats (ghee! coconut oil! lard! tallow!) since these will not oxidize as readily.  You should be cooking at a lower temperature anyway, so as not to exceed the smoke point of the oil you’re using.
4. Avoid Aging! Purchase oils in small quantities, such that you would use them in a couple of months.  Avoid the urge to save money by buying oils in bulk; they will go rancid and kill you.

The following study, published in the American Journal of Clinical Nutrition, performed a meta-analysis of 60 controlled trials and produced the following interesting conclusions.

The study found the following affects of replacing carbohydrates with fatty acids:

1. Saturated fats increase your HDL the most.
2. Mono-unsaturated fats are next; and
3. Poly-unsaturated fats increase HDL, but only about half as well as the saturated fats do.
4. Trans fats lower your HDL (those EVIL trans-fats!)

Unfortunately they come to some highly suspect conclusions when you look at their data, and you’ve got to be suspicious of the conclusions of any study that cites Ancel Keys in its references

Some other pearls of wisdom:

1. Increasing your HDL will lower your risk of coronary artery disease (CAD).  The ratio of HDL to total cholesterol is an important indicator of CAD risk.
2. Replacing carbohydrates in your diet with fats (saturated, mono-unsaturated, and poly-unsaturated) increases your HDL (good!) and decreases your triglycerides (also good!).
3. Saturated fats have gotten a bad reputation since they increase total cholesterol.  However, most of this increase is due to an increase in the HDL (good) cholesterol.
4. Replacing saturated fats in your diet with unsaturated fats will actually lower your HDL cholesterol (that’s bad).
5. Omega-3 polyunsaturated fatty acids will reduce your triglycerides.  Omega-6 polyunsaturated fatty acids will increase your triglycerides.
6. Lauric Acid (saturated) showed the best ability to raise HDL for its corresponding increase in LDL.  You can find this in coconut fat.
7. Stearic Acid (saturated) was the best of the saturated fats, though, because it both lowered LDL and raised HDL. (You find this in beef fat and cocoa butter–chocolate!).  Your body just converts stearic acid into monounsaturated fats anyway.
8. High Carbohydrate diets lower your HDL, increase your triglycerides, increase your risk of heart attack, but also shift your lipid particle size to be smaller and denser (which causes the fats to ooze into the arterial intima of your blood vessels).
9. Trans fats were worse than carbohydrates at increasing HDL, increasing LDL, and increasing triglycerides.