Mike:
>Every protein is different and only be
>partially  replace by an other protein (some are very close though).

Of course every protein is different, but for the body, only the breakdown
components (essential amino acids) are important. If you stick to
vegetable sources of protein, you won't be protein deficient if the forms
of protein are varied enough (vegetable proteins are usually deficient in
1 or more amino-acids, but there is an amino-acid "pool" in the body, so
it's not necessary to balance each meal in amino-acids).

I think that animal food is useful for other reasons. First, essential
fatty acids like EPA and DHA are present only in animals (and are
important for the brain, among others). Vegetable fat usually contains
some ALA (alpha linolenic acid), but the conversion of ALA into EPA and
DHA is perhaps not efficient enough). Secondly, some minerals are much
more bioavailable from animal than from plant sources, like iron (in
"heme" form) and zinc. And of course, the B12 stuff. Some organs are foods
of especially high quality, like liver (excellent source of vitamin A,
folate and B12).

The question is of course: how much should we eat?

Chimpanzees eat on average 5% animal, and share more than 99% of their
genome with humans; but remember that in the remaining 1% lie the genes
that enable our brain to be (proportionally) 3 times larger, and thus we
probably have different nutritional requirements.

Hunter-gatherers eat on average 65% animal (by calories), 33% for Bushmen
and almost 100% for eskimos. Instinctos can notice that wild game give a
clearer stop, but probably the main reason is the lack of fat: eskimos
typically eat 33% protein and 66% fat. If you stick to muscle meat from
wild game, then of course you won't eat a lot. To incorporate more animal
food in your diet, it's necessary to eat all parts, like organs and bone
marrow.

Wild fruits are also much less sweet, which explains why instinctos eat
more fruit and less meat than hunter-gatherers.

Now, the question: what is the relation between being blocked,
overloading, eggs, liver, sea vegetables, etc?

 *First there is the notion of "neophobia": a new food always tastes much
worse than a known food. That phenomenon is much more marked in animals
than in humans, who can acquire tastes much more easily. Imitation of
peers, exposure contribute to developing a taste. This explains why:
   -you can be blocked to something that you have never eaten cooked (like
sea vegetables). In fact, since you have never eaten it at all (raw or
cooked), it's a new food for you, so it tastes worse than what it
"should".
   -you can "unblock" for a food by eating it cooked for a while. Indeed,
the stops are much weaker when the food is cooked, allowing you to ingest
it, and, after some time of exposure, the food becomes familiar and
"neophobia" is suppressed.

 *Secondly, aversions are extremely difficult to reverse. If you eat a
food, and become sick just afterwards for whatever reason (e.g. because
you have been on a rough sea), then you'll likely develop an aversion to
it. Even if you (intellectually) know the real reason for you aversion,
you won't reverse it easily, ever after many years. And aversions can
increase if someone forces you to eat something you dislike (as often
happens with children), which may explain why you can be blocked to eggs,
many years after having been forced to eat them cooked as a child.


I am not denying that overloading exists. Certainly, if you eat too much
meat, your body will start craving some nutrients of fruits and
vegetables. I just don't think that overloads can stil be there after 20
years.


Best wishes,

Jean-Louis
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