Actually, cholesterol seems to be quite resistant to oxidation, for example:
"...In the presence of the physiological concentration of cholesterol in phopholipid bilayers, the amount of hydroperoxides produced by ionizing radiation is dramatically reduced. The packing effect of cholesterol in phopholipid bilayers is well recognized, as well as its influence on the reduction of water concentration in the bilayer. The dramatic reduction of hydroperoxides concentration observed when irradiation is performed in the presence of cholesterol probably originates from a steric hindrance to the radical chain reaction through the unsaturated lipids due to the presence of cholesterol."
Source: Free Radic Biol Med. 1995 Oct;19(4):511-6.
The biggest problem seems to be oxidized LDL. LDL is a protein molecule that "holds" lipids - cholesterol and fatty acids. When LDL contains a lot of PUFAs, experiments have shown that it is much more susceptible to becoming damaged, which then leads to "coronary heart disease." I don't know if the evidence is so clear on oxysterols, which is what oxidized cholesterol molecules are called - you can do an internet search for oxysterols in food and see if there is something really on point. I found the following, which is problematic because they used rabbits, which are animals that don't naturally ingest cholesterol:
"...oxidation of triglyceride-rich lipoproteins was significantly greater in rabbits fed oxidized cholesterol compared to the pure cholesterol-fed animals. The oxidized cholesterol-fed animals also had a 64% increase in total aortic cholesterol, despite lower plasma cholesterol levels compared to the pure cholesterol control animals. Taken together these results suggest that dietary oxysterols may substantially increase the atherogenicity of lipoproteins."
Source: The Journal of Lipid Research, Vol. 39, 1995-2004, October 1998.
If you read this study on the internet, at http://www.jlr.org/cgi/content/full/39/10/1995, you can go to the bottom of the page and read through the references. My guess is that if you follow a diet such as the one I do, there will be very little oxidized cholesterol in it. |
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