On Mon, 7 Aug 2000, Amadeus Schmidt wrote:
> (SFA may be computed without short chain saturated fats, which are pure
> fuel and don't interfere with EFAs)
>
> Nature fat sources from vegetables (the richest source beeing nuts)
> generally have very high EFA and low SFA parts. (e.g. walnut 6:9:47)
Well if you eat 100g of walnuts you get about 5.6g of SFAs,
almost all of which are long-chain (16:0 and 18:0). If you eat
100g of beef (composite) you get 8.5g of SFAs, almost all of
which are long-chain. If you choose leaner cuts (see bottom
round, trimmed to 1/8 inch fat, for example) then 100g gets you
4.4g of SFAs (mostly long-chain), less than walnuts. It also
gets you more protein, but a lot less MUFA and PUFA.
But as you know, not all PUFAs are equal. You have chosen
walnuts for an example. They are unusual (among nuts) in that
they are relatively high in w-3 fat. If we consider 100g of
almonds instead, we find that there's still 4.9g of SFAs (mostly
long-chain), more than bottom round beef. There's lots of PUFAs
too, but almost all are w-6. The ratio of w-6 to w-3 EFAs is
about 28:1. For hazelnuts the ratio is better, at about 6.6:1,
but the SFA content is about the same. And of course the nuts
are very high in MUFAs.
Since you claim that both SFAs and MUFAs are competing with EFAs
for enzymes, then perhaps what matters is the ratio (SFA +
MUFA)/PUFA, in which case nuts certainly do better than meats.
But most nuts have an extremely high w-6:w-3 ratio (with the
exception of walnuts), whereas meats do not.
> 2.High percentages of animal (and other) fat in the food are probable only
> for rather short timeframes in human history. If you accept the CroMagnon
> anchestorship this are only 30ky of 200ky. And this also betrays only
> the CroMagnon groups which invaded ice age Europe. Regarding the lower
> bioproductivity in glaciated climates this was probably a limited
> percentage.
I doubt it. Cordain's kangaroo study suggests that even in arid
Australia there is still a good deal of fat to be harvested from
the carcass of even a lean animal like a kangaroo. My guess is
that such foods were exploited as completely as possible, for a
very long time.
> 4.Long chain saturated fats and monounsaturated fats decrease the
> availability of essential fatty acids, which have a fundamental
> overall health effect by determining prostaglandins.
> This by crowding out EFAs from the enzymes which ought to put them to work.
> delta-6-desaturase (D6D), elongase, and delta 5 desaturase.
Then nuts are going to be problematic, since most of them are
overwhelmingly composed of MUFAs. And the EFA ratios would cause
further problems. This may be why many people get acne, an
inflammatory response, from heavy consumption of nuts.
> The working of D6D is further diminished by some more factors as are
> -trans fatty acids
> -insulin (source for me only Sears)
> -alcohol
> -cholesterol (source for this only Erasmus)
I haven't seen cholesterol cited as an inhibitor of D6D. My
sources, in addition to Sears, show a high-carb diet as the
single most potent inhibitor of D6D, because of the insulin
effect.
> Foods containing arachidonic acid (AA) like beef work independent of
> D6D and above mentioned enzymes but are producing Series 2 ("bad guy")
> prostaglandins only.
This is incorrect. More recent work indicates that dietary AA
has little or no effect on prostaglandins. The riches dietary
source of AA is eggs, and there is no evidence that egg
consumption affects prostaglandins significantly.
> Foods containing EPA like fish oil or brain work independent of
> D6D and above mentioned enzymes and can produce Series 3
> prostaglandins which can downregulate AA usage again.
Yes.
> 5.Examples of real-world people which are thriving in presence of
> much saturated fat (Masai, Samburu, Jamaicans) are likely to rely mostly
> on short chain SFAs as are found in the dairy and coconut they consume.
Dairy fats do have some short-chain SFAs, but the long-chain ones
are overwhelmingly predominant. In coconut oil, medium-chain
fats (10:0, 12:0, and 14:0) predominate, with long-chain fats
next, and short-chain last.
> 6.Unavailability of EFAs in presence of long chain EFAs possibly leads
> to usage of sticky SFAs in cell membranes, makem them less elastic and less
> permeable. Further they reduce the usability of cholesterol, which is
> otherwise used in cell membranes.
Then the populations mentioned above should be very sick. Why
aren't they?
> 7.Replacing carbohydrate by fats helps prople diseased by
> diabetes or glucose intolerance. Probably obesity too.
But if your theory is right, animal fats should interfere with
glucose tolerance, by making membranes less permeable to glucose.
Why isn't that so?
> > And the most potent
> >stimulator of desaturase enzymes is glucagon. The best way to
> >keep insulin low and to produce glucagon is to eat a low-carb,
> >high-protein diet.
>
> Glucagon is produced shortly after insulin levels after a meal goes down,
> to ensure a constand blood sugar as necessary for our brain.
> This should be the case the whole night and 2-3 hours after a meal.
> Right?
Glucagon is also stimulated by protein (and, incidentally, by
stearic acid).
> A high protein meal as well as a carb meal produces a insulin surge.
Yes, but protein still produces less insulin than carbs,
according to the Westphal data, which is the most recent I can
find.
> > I believe that in the context of such a diet,
> >and perhaps *only* in that context, the body handles SFAs well.
>
> Maybe. Jamaicans are certainly not low carb nor very high in protein.
You think? The Jamaicans I know use lots of meat, especially
goat. They eat a good amount of fruit, but fruit sugars have
less effect on insulin, and lots of vegetables.
> >3. Between 1910 and 1970 (in the U.S.) consumption of animal fats
> >went down somewhat, while overall fat intake went up. In 1910,
> >84% of fat eaten was animal fat,...
> > But the main point is that ...
> > the animal fats were apparently not causing trouble.
>
> Ok, how much was dairy and how much overall calories were from fat 1910?
As I already pointed out, dairy fats are high in long-chain SFAs.
I don't have the numbers in front of me, but overall calories
from fat were just a few percent lower in 1910, compared to 1970.
Something like 40% in 1910 and 43% in 1970. That may be off a
bit, but it's about right.
People in 1910 used lard, tallow, and butter in their cooking.
> We'll see. Of course they can change their minds.
> In the complicated computation in your (Cordaine's) kangaroo posting
> suddenly the bodyfat of kangaroo rose from almost nothing to 50%
> of food energy. I'd like to see a whole animal analysis, with sums.
Well, that will be in the published version, no doubt. I'm
betting that the whole-carcass fat breakdown will be about 45%
SFA, 50% MUFA, and 5% PUFA.
> I think the aborigines know what they do.. if they leave a dead
> kangoroo if it's not fat enough. Keyword protein toxicity.
But the point is that they don't have to leave much behind.
Todd Moody
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