Juergen Botz:
> I have a hypothesis. It is this: if a human eats saturated fat but not
> a
> lot of carbs, especially highly glycemic carbs AND his total caloric
> intake does not exceed his daily needs, then most of his energy will
> come from the fat, and the fat consumed will be burned fairly
> completely.
> In this case he will NOT suffer the supposed negative effects of
> saturated
> fat consumption (and consequent risk of heart disease).
>
> If on the other hand a human eats a diet high in carbohydrates PLUS a
> lot
> of saturated fat, OR he regularly eats lots of saturated fat and his
> total
> caloric intake exceeds his daily needs, then he will incompletely
> process
> some of these SFAs (saturated fats) and consequently experience
> elevated
> cholersterol, arterial plaque, inflammation, and eventual death from
> CHD.
It sounds plausible, and as you noted, one of the studies supports that
hypothesis. Also, Cordain mentioned in The Paleo Diet that the negative
effects of carbohydrates is increased when combined with fats and salt.
> > [SF is a strong predictor of CHD mortality in middle aged American
> Indians.]
>
> Are these Indians by any chance overweight and drinking too much?
> Sorry
> about the stereotype, but alcohol is a high-glycemic carbohydrate, and
> middle aged American Indians are known to consume a lot of it on
> average.
The abstract does say "independent of other established CHD risk factors,"
but it doesn't say what those factors were. Also, other studies that
examined broader American populations did not find the same connection
between SF and CHD.
> > [Beef Fat Increased LDL; subjects were restricted to nonfat dairy to
> avoid
> > confounding data with SF from dairy foods; cited by Loren Cordain,
> Ph.D.]
> > Am J Clin Nutr. 1990 Sep;52(3):491-4.
> > Cholesterol-lowering effect of a low-fat diet containing lean beef is
> > reversed by the addition of beef fat.
>
> Ok, here we just need to know a bit more about this "low-fat diet"...
> but
> it's a good guess that it's a classic high-carb diet and not a Cordain-
> style
> low-fat paleo diet. If so, it still fits the hypothesis.
Yes, they do mention that it was a high-refined-carb diet in weeks 2-3
because it included two refined carbohydrate supplement drinks per day. This
supplement was cut in half in week 4 and eliminated in week 5, when LDL was
highest, but the carb proportion was still fairly high at 43.6% (maximum for
hunter-gatherers is 40% of total energy). A low carb diet may not have
resulted in LDL increase.
> What could invalidate this hypothesis? High incidence of heart disease
> amongst traditional peoples living on a mostly or completely
> carnivorous diet,
> for example. Any studies for or against?
All observations and studies of HG's and most traditional peoples have found
low incidence of heart disease, including those on mostly carnivorous diet
(such as the Greenland Inuit Eskimo--who inspired the term "Inuit paradox").
There is plenty of info on this from multiple sources.
-----------
[SF is a strong predictor of CHD mortality in middle aged American Indians.]
Dietary fat intake and risk of coronary heart disease: the Strong Heart
Study. Am J Clin Nutr. 2006; 84(4):894-902. Xu J ; Eilat-Adar S ; Loria C ;
Goldbourt U ; Howard BV ; Fabsitz RR ; Zephier EM ; Mattil C ; Lee ET.
Center for American Indian Health Research
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Ab
stract&list_uids=17023718
> "[B]ased on one 24-hour dietary recollection on the part of the
participants. The rest of the paper was available to members only, and we
know nothing about their typical diet from the abstract." --Lynnet Bannion
Yes, since the full paper is not accessible, we don't know how much of the
SF was from dairy. Effect of SFAs could possibly be due to just dairy fats
rather than meat fats. Also, carbs could also have been high if they didn't
control for carbs.
[SFAs were found to be positively associated with the inflammatory markers
C-reactive protein and circulating interleukin [IL]-6 in overweight men, but
not lean men] Fernandez-Real JM, Broch M, Vendrell J, and Ricart W. 2003.
Insulin resistance, inflammation, and serum fatty acid composition. Diabetes
Care 26:1362-1368.
1 Unitat de Diabetologia, Endocrinologia i Nutrició, University Hospital of
Girona "Dr. Josep Trueta," Girona, Spain
2 University Hospital of Tarragona "Joan XXIII," Tarragona, Spain
http://care.diabetesjournals.org/cgi/content/full/26/5/1362
> "[A]sked no questions about diet but instead looked at the fatty acid
levels in the blood, as indicative of their diet. High levels of saturated
FA in the blood raised inflammatory markers such as C-reactive protein."
--Lynnet Bannion
This one is not easy to explain away, though the study is limited and so
only suggestive, rather than conclusive. Perhaps the subjects with high
levels of serum SF consumed more carbs as well as SF than those with low
levels of serum SF.
[Beef Fat Increased LDL; subjects were restricted to nonfat dairy to avoid
confounding data with SF from dairy foods; cited by Loren Cordain, Ph.D.]
Am J Clin Nutr. 1990 Sep;52(3):491-4.
Cholesterol-lowering effect of a low-fat diet containing lean beef is
reversed by the addition of beef fat.
O'Dea, K et al
Department of Human Nutrition, Deakin University.
http://www.ajcn.org/cgi/content/abstract/52/3/491
> "While LDL went down during the low-fat weeks 2 and 3, and up only in week
5, TG levels rose significantly during weeks 2, 3 and 4, and only dropped in
week 5. HDL levels dropped during weeks 2 and 3, and recovered in week 5.
It is interesting to read the article." --Lynnet Bannion
Yes, replacing carb powder with beef fat resulted in lower triglycerides and
higher HDL, in addition to the higher LDL. Also, increased LDL is not
directly associated with CHD.
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