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Wednesday, January 1, 2014

Vegetable Oils

Previously on this Blog, we discussed the dietary fat mis-information that has been circulating since the early 1950's.  Yesterday's Blog posting discussed the pros, cons, comparisons, and contrasts between the animal fats from beef, pork, and chicken.

Today, we can discuss the known facts for vegetable oils.   Most everybody agrees that trans-fats are bad for us.  These are mainly formed by taking vegetable oils and reacting them with hydrogen under high temperature, vacuum, and usually with a catalyst, to create cheap, semi-liquid fats that can be used in margarine and prepared foods.  In other words, avoid partially hydrogenated oils, and the margarines that contain them.

Oil expressed from olives, nuts, and other fruits were made from before the Pyramids were built.  Generally, these are preferred.

Olive oil (depending on its source and manufacturing methods used) is composed of:
  • 55% to 83% oleic fatty acid, a mono-unsaturated Omega-9 fat.
  • 3.5% to 21% linoleic fatty acid, an Omega-6 poly-unsaturated fat.
  • 0.3% to 3.5% palmitoleic fatty acid, an Omega-7 mono-unsaturated fat
  • <1% α-Linolenic acid, an Omega-3 poly-unsaturated fat 
 The USDA provides the following as typical olive oil in N. America:
  • 73% mono-unsaturated fat
  • 14% saturated,
  • 11% poly-unsaturated fat
The 73% mono-unsaturated fat in olive oil simultaneously raises HDL ("good cholesterol"), and lowers LDL ("bad cholesterol"), which has significant beneficial dietary health effects.   The 14% saturated fat simultaneously raise both HDL and LDL, somewhat cancelling each other out as to the health effects.
Cottonseed Oil + P&G= Crisco
Cotton seeds were a waste product from the cotton gins that produced raw cotton for making cloth.  In 1911, Proctor & Gamble collected these cotton seeds for free, developed a process to extract the oil, clean it, hydrogenate it, and created Crisco shortening.

In 1930's soybeans were imported from China to N. America  for the first time.  By the 1950's soybean oil was a popular vegetable oil.  Today, soybean oil is virtually tied for 1st place with palm oils for world-wide consumption.

In the 1980's canola oil rapidly increased in popularity in N. America as a light, low taste oil, "perfect" for salad dressings, frying, and factory processed foods (eg. muffins, boxed cereals, etc.).

Some vegetable oils (eg. corn oils, soybean oil, etc.) are extracted from their seeds, nuts, and fruits by using petroleum solvents such as hexane (similar to gasoline).  Virgin olive oil means that no solvents were used.  There is a growing concern today about the residual effects from these solvents.  Use of petroleum solvents is not permitted for organic certified foods.

Triglycerides are the main constituents of vegetable oil (which are typically more unsaturated) and animal fats (which are typically more saturated).  Many people remember the warnings against all forms of cholesterol, said to be artery clogging.  That was the quackery of Ancel Keyes which is still with us today.  The science is a little more complicated that Keyes' simple, but wrong, hypothesis.

There are 4 major types of cholesterol in our blood:
  • VLDL (Very Low Density Lipoprotein), which is used by the body to enwrap and carry most of the triglycerides flowing with the blood.  VLDL is "bad" cholesterol, created by the liver as a triglyceride and cholesterol transport mechanism.
  • IDL (Intermediary Density Lipoprotein), which is a VLDL that has discharged most of the triglycerides and cholesterol that it had previously contained. Some IDL get absorbed by the liver, while others lose further triglycerides while in the bloodstream, and eventually become LDL.

  • LDL (Low Density Lipoprotein), a.k.a. "bad" cholesterol.  LDL is the format where most of the cholesterol in the blood can be found.  There are 7 sub-types of LDL.  The small-dense LDL particles are the ones that cause the greatest cardiovascular damage.  See Krauss

  • HDL (High Density Lipoprotein), a.k.a. "good" cholesterol

Ancel Keyes, the quack, measured total cholesterol in the blood (ie. HDL+LDL+IDL+VLDL), as this was easy to do in 1950's, and he couldn't differentiate (it was total cholesterol measurements, or nothing, so that is what he used).  Some doctors continue to do total cholesterol measurements today, only because they can still do so cheaply and easily; even though the total cholesterol levels has little or no predictive power for future health or disease; and is therefore a dis-service to their patients.

In 1956, American Heart Association's journal Circulation published a minority report by Dr. Gofman at USC Berkley, which reported that adding the blood's concentration of VLDL + LDL was the best predictor of future heart disease (ie. the Atherogenic Index).  Today, the best known indicator is VLDL + LDL+Triglycerides in the blood.  Alternatively, HDL:Total (the algebraic equivalent proxy measurement) is highly predictive of disease and mortality.

What Causes HDL, LDL, VLDL to Vary?
  • HDL ("good cholesterol") is increased by physical exercise, weight loss, and a low carbohydrate diet.
  • LDL ("bad cholesterol") is increased by dietary saturated fat consumption.
  • VLDL (""bad cholesterol") is increased by dietary carbohydrate consumption
Therefore simultaneously eating saturated fats plus carbohydrates (eg. deep fat fried doughnuts with a sugar glazing) would simultaneously drive up both VLDL and LDL, thereby compounding the risk of heart disease many times over.

Today, many medical doctors who are behind the times will take the ratio of HDL:LDL as being indicative of health, and prescribe medications (ie. statins, or other cholesterol lowering medications) when this ratio goes out of whack. Again, this is a bad habit, as taking the ratio of LDL to total cholesterol would be a far better predictor of health (ie. the lower the ratio of LDL:Total Cholesterol .  Secondly, total triglycerides in the blood would also be a better indicator of health than the HDL:LDL ratio.

In reality, dietary triglycerides are highly correlated with cardiovascular disease, while the relationship between cardiovascular disease and total cholesterol is slight to non-existent.  Generally, most foods that contain triglycerides also contain some cholesterol, and most triglycerides are transported in the blood by lipoproteins than contain both triglycerides and cholesterol, and it is believed that these two facts account for that slight secondary effect.  The main killers are triglycerides, and the small, dense sub-type of LDL cholesterol.

Omega-6 fatty acids come mainly from vegetable grains such as palm, soybean, sunflower, canola, corn, safflower, etc.  These oils are relatively cheap, and are therefore heavily used in factory prepared foods, and restaurant foods.  Omega-6 oils have been associated with causing or contributing to inflammation diseases (eg. rheumatoid arthritis, inflammatory bowel syndrome, etc.).

Excess dietary Omega-6 fats are said to interfere with the health benefits of Omega-3 fats.  Therefore Omega-6 to Omega-3 ratios have become an important indicator of acceptable dietary fat intake.

Yesterday's Blog posting discussed the ideal Omega-6 to Omega-3 ratios of  less than 4:1, but the typical N. American diet is between 10:1 to 30:1; well away from the ideal.  We eat way too much processed, factory foods for our own good.

Way too much vegetable oils in our diets are one of the leading causes of these poor Omega-6:Omega-3 ratios.

By eating more chicken rather than vegetable oils, our Omega-6:Omega-3 ratio can be significantly improved.  By eating pasture-raised chicken rather than #ChickenMafia raised chicken, our Omega-6:Omega-3 ratio is maximized.

All of this should lead to better health and less disease.




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