While researching the origins of milk drinking by homo sapiens, I came across an interesting discussion by, (believe it or not), The International Network of Cholesterol Skeptics. In this discussion, they were offering dissenting viewpoints on Loren Cordain's position on cholesterol.
Anyway, I've quoted a portion of the last article on that page, because it caught my eye:
Here is a link to that site:"Another consequence of leaving milk fat to sour is that the cholesterol contained therein undergoes some spontaneous oxidation, forming oxysterols. Oxysterols have the property of preventing crystallization of cholesterol from supersaturated solution. I believe it is the crystallization of cholesterol from the plasma lipids that are deposited in the arterial intima that renders that cholesterol atherogenic; and that adequate oxysterols in the diet could prevent that from happening.
I should add that meat has been preserved for millenia by allowing it to dry in the air.The same oxidative changes occur in the cholesterol in meat
In my view, the critical change in the human diet with relevance to atherogenesis was the alteration in food handling techniques allowed by refrigeration, introduced in the developed world early in the 20th century. This inadvertently largely eliminated the spontaneous generation of oxysterols in foods of animal origin, removing these compounds from the human diet."
http://www.thincs.org/discuss.cordainagain.htm
Since I had never heard of oxysterols before, when I looked it up, I found it to be a rather controversial subject. Here is a comprehensive discussion on studies regarding the relationship between oxysterols and cholesterol. Unfortunately, discussions on oxysterols tend to get rather deep at times, but down toward the bottom of the article, in the next to last paragraph, is this quote:
"Since oxysterols mimic many of the effects of cholesterol, dietary oxysterols might be expected to be atherogenic, but clear evidence for this is lacking. A great number of studies have been published on effects of dietary oxysterols on experimental animals (for an excellent review, see ref. 41). Of 13 such studies, six indicate a proatherogenic effect, four an antiatherogenic effect, while three show no significant effect."
This is from this site:
http://www.jci.org/cgi/content/full/110/6/725
Here is reference number 41, cited by that article:
http://tinyurl.com/pql4o
Ok, all this information seems to point to the conclusion that oxysterols may be atherogenic, (capable of producing atheromatous plaques in arteries). So why does Leib Krut, (the author of that article in my first quote, about the milk-souring process), believe that oxysterols are a good thing? Is anyone aware of any research that has substantiated his suggestion that adequate oxysterols in the diet could prevent the crystallization of cholesterol from the plasma lipids, (in human arteries, not just in vivo)?
It is relatively easy to find articles about research with animals, that have a negative outcome. Here is one, for example:
http://www.ncbi.nlm.nih.gov/entrez/quer ... t=Abstract
This study, for example, concluded that serotonin induced exacerbated coronary vasoconstriction was completely reversed by dietary oxysterols, however, oxysterols cannot be used as agents against excess dietary lipid-induced coronary spasm, because of their atherogenic properties.
Tex
