here I am!
I think a couple things are interesting. 1, in most of the other studies I posted, the tarahumara appeared to have markers of malnutrition, such as decreased stature, several vitamin and mineral deficiencies, etc., dating all the way back to 1980. Incidently, many suffer from heart problems, supposedly from all of that running (in another study I posted).
Also, genetics may play a large role in the success that they have had on their diet. Like the study Darryl posted here, this is the first time that dietary cholesterol correlated with serum cholesterol. Genetic drift is a definite possibility here given the extremely limited outbreeding and population size. Lastly, if this is not the case, who is to say that serum cholesterol being that low is beneficial? I remember reading some studies that correlated excessively low cholesterol to high mortality/morbidity, I'll look for them.
Finally, another important thing is that their diet is HYPOcaloric. Diseases of overnutrition (such as obesity, heart disease, etc.) would clearly not have a place in their lives...however, undernutrition may.