Loren is having a little trouble with his mail software. I'm working
with him to solve this issue but in the meantime here is a response he
has written to various things that have been discussed this week. With
luck any further comments can come from him directly.
Dean
--[begin Dr. Cordain's letter]---
Greetings! I have enjoyed reading the paleodiet digest to date but
have been somewhat reticent to make any comments simply because of my
unfamiliarity with the format. Thanks to some helpful hints from
Dean, I hope that this message makes it through.
Both Staffan and Ward have commented upon the macronutrient content
of preagricultural diets and Staffan has suggested that I provide my
input. What follows is a portion of a message that I have previously
sent to Staffan.
Although Richard Lee (1) and others have suggested that the average
macronutrient content of all world wide hunter gatherers was derived
>from a subsistence pattern of 35% animal food and 65% vegetable food,
it has been shown that these figures are likely erroneous (2). Lee
derived his macronutrient percent estimate from compiled data from the
Ethnographic Atlas (3), however it has been shown that he distorted the
original data by reducing the number of North American cases and by
reclassifying shellfishing into a gathering activity (2). A
re-analysis of the data in the Ethnographic Atlas shows results much
different from those which Lee originally presented. Indeed for most
(77%) of the societies listed in the Ethnographic Atlas, gathered plant
food contributes less than half the calories (2). Leonard et al. (4)
in an analysis of 5 recently and carefully studied hunter gatherer
groups (!Kung, Ache, Hiwi, Inuit and Pygmies) has shown the mean value
for energy intake from animal food sources to be 59%. Leonard et
al.'s (4) data include Lee's analysis of the !Kung diet which contains
33% of its calories from animal food. However, careful analysis of
the !Kung diet shows that of their daily intake of 2,140 calories, only
190 calories were derived from plant foods other than mongongo nuts.
Because of the close proximity of an enormous mongongo nut forest, it
is likely that the !Kung data is not representative of a typical
hunter-gatherer. Since vegetable food is virtually unavailable to the
Inuit, who obtain 96% of their caloric intake from animal food, this
data is also unrepresentative of the typical hunter gatherer. An
average value for the Leonard et al. (4) data without these two extreme
values would show that 56% of the calories were derived from animal
foods. In her classic study of Australian Aborigines temporarily
reverting to a hunter-gatherer lifestyle, O'Dea (5) showed that animal
foods contributed 64 % of the total energy (6). The macronutrient
breakdown was 54 % protein, 33% carbohydrate and 13% fat (6). These
values are significantly different than those now almost universally
accepted by my friend and co-author, Boyd Eaton et al. (7) of 34.2%
protein, 44.3% carbohydrate and 21.5 % fat.
Clearly, the carbohydrate content of the average paleolithic diet
varied according to geographic location, latitude and season; however
in aggregate, it almost certainly was significantly lower than the 55%
carbohydrate recommended by the American Heart Association Diet.
Except for seasonal occurrences of honey and dried fruit, its
carbohydrates were rich in fiber and of a low glycemic index. The
paleolithic diet was devoid of starches from cereal grains, and
starches from legumes and tubers generally contributed fewer calories
than those from animal derived foods. Prior to the regular use of
fire, many tubers almost all legumes would have been unavailable for
consumption because of their high antinutrient load (8). Since
animal sources almost always contributed the majority of total daily
calories (an average value would probably be between 55-65%), it is
unlikely that the carbohydrate content could have regularly exceeded
40% and under most circumstances was probably between 30-35%. As
humans moved into more extreme latitudes (>40-45degrees N or S),
carbohydrates would have contributed even fewer than 30-35% of the
total calories, particularly during winter or early spring. So, with
this enormous caloric intake derived from animal foods, how can the
seeming paradox of low serum cholesterol (and presumably reduced risk
from coronary heart disease), observed in virtually all hunter
gatherers, be explained? Recent studies by Wolfe and co-workers
(9,10,11) have shown that isocaloric replacement of carbohydrate with
animal derived protein improves all lipid profile indices including
total CHOL, HDL, LDL and VLDL. A high protein diet similarly improves
virtually all indices of type II diabetic control and symptoms of
Syndrome X (5) whereas low fat, high carbohydrate diets have been
repeatedly shown (in tightly controlled dietary kitchen studies) to
worsen HDL, VLDL, triglyceride and total CHOL/HDL ratios (12,13,14).
On another unrelated matter, I have received notification that many
scientific journals including NEJM will now refuse to publish any
material which has appeared previously on the Internet. Consequently,
I think that as scientists and authors, it is important that we use
this forum to share ideas and thoughts on the paleolithic diet, but to
be somewhat guarded in putting out portions of our unpublished work for
common disposal. Clearly, individual e-mail messages between two
scientists do not constitute a risk. Perhaps Dean could comment
upon this.
Cordially,
Loren Cordain, Ph.D.
References
1. Lee RB. What hunters do for a living, or how to make out on
scarce resources. In Lee RB, DeVore I (Eds). Man the Hunter.
Chicago: Aldine, 1968:30-48.
2. Ember CR. Myths about hunter gatherers. Ethnology
1978;17:439-48.
3. Murdock GP. Ethnographic atlas: a summary. Ethnology
1967;6:109-236.
4. Leonard WR, Robertson ML. Evolutionary perspectives on human
nutrition: the influence of brain and body size on diet and metabolism.
Am J Hum Biol 1994;6:77-88.
5. O'Dea K. Marked improvement in carbohydrate and lipid metabolism
in diabetic Australian Aborigines after temporary reversion to
traditional lifestyle. Diabetes 1984;33:596-604.
6. Naughton JM, O'Dea K, Sinclair AJ. Animal foods in traditional
Australian diets: polyunsaturated and low in fat. Lipids
1986;21:684-90.
7. Eaton SB, Konner M. Paleolithic nutrition. A consideration of its
nature and current implications. N Engl J Med 1985;312:283-89.
8. Stahl AB. Hominid dietary selection before fire. Current
Anthropology 1984;25:151-68.
9. Wolfe BM, Giovannetti PM. Short term effects of substituting
protein for carbohydrate in the diets of moderately
hypercholesterolemic human subjects. Metabolism 1991;40:338-43.
10. Wolfe BM, Giovannetti PM. High protein diet complements resin
therapy of familial hypercholesterolemia. Clin Invest Med
1992;15:349-59.
11. Wolfe BM. Potential role of raising dietary protein intake for
reducing risk of atherosclerosis. Can J Cardiol 1995;11(supp
G):127G-131G.
12. Gonen B, Patsch W, Kuisk I, Schonfeld G. The effect of short
term feeding of a high carbohydrate diet on HDL subclasses in normal
subjects. Metabolism 1981;30:1125-29.
13. Coulston AM, Liu GC, Reaven GM. Plasma glucose, insulin and lipid
responses to high carbohydrate low-fat diets in normal humans.
Metabolism 1983;32:52-56.
14. Chen YDI, Coulston AM, Zhou MY, Hollenbeck CB, Reaven GM. Why do
low fat high carbohydrate diets accentuate lipemia in patients with
NIDDM? Diabetes Care 1995;18:10-16.
--[end Dr. Cordain's letter]--
=========================================================================
Date: Wed, 26 Mar 1997 23:43:46 -0500
From: Dean Esmay <[log in to unmask]>
Subject: On the issue of publication
Regarding Loren's concern about prior publication issues, I do not have a
definitive answer. But I can provide some information and suggestions that
might be helpful:
As of today there are about 40 persons signed up for this list. I cannot
imagine membership ever exceeding about ten times that amount. The list is
also not a "publication" per se, as what is written here is not generally
distributed to anyone other than list members. Considering a small group of
maybe a few hundred people exchanging informal comments a "publication"
would be a stretch indeed. Which is not to say that some hard-nosed editor
couldn't possibly see it that way, but I would be surprised if one did.
However, all messages posted to this list are archived. We hope at some
point to make these archives available through the World Wide Web so they
may be read by others who wish to learn about this field or catch up on
previous conversations. The existence of these archives, even though they
can only be seen if someone specifically goes looking for them, might
arguably be considered a form of "publication" by the editors of some
journals. This is some cause for concern.
But I think there are a few things that can prevent any problems:
1) Any message you write to this list is, by current copyright law,
automatically copyrighted by you. Which means that, beyond the
distribution to list members which you implicitely agreed to when you wrote
to the list, no one has any right to further redistribute anything you
write without your express permission. This does not mean that someone
cannot do so, but they have no RIGHT to do so and have legally violated
your rights if they do.
2) Because anything written to the list by any list member is copyrighted
by that member, I will, upon request, remove any individual message from
the archives. The messages are, after all, not my property.
3) You may also at any time further protect yourself by simply writing, at
the top or bottom of any message, a protective statement. An example would
be: "This message is copyright 1997 by Dean Esmay. This message may only
be distributed privately to members of the Paleolithic Diet & Exercise
Symposium discussion group, and may not be reprinted or otherwise
distributed by anyone to anyone. These constitute informal comments to
colleagues and are not for publication."
Technically, by copyright law, you do not have to attach such a statement
to be protected. However, adding such a statement will be additional
protection, emphasizing the nature of the communication and serving as an
easy verification to anyone who asks that what you wrote was PRIVATE
CORRESPONDENCE TO A SMALL GROUP and not for publication. (And I will fully
back anyone up on that if necessary.)
4) Most of the time common sense should be sufficient. If you don't say
anything here that you wouldn't say to a journalist from DISCOVER magazine
who called you for an interview, it's unlikely you'll ever have any real
trouble.
I'm glad Loren brought this up though, as discussing it now may avoid grief
later.
|
