Dear Members,
Answering to a few questions on digestibility of cooked foods of the Paleodiet digest of 3-4 Sept. 1997,
either asked or forwarded by Ward Nicholson <[log in to unmask]>:
Some of the answers can already be found in the archives of Paleodiet digests of May 5-17, 1997. For a start,
look for comments from Jennie Brand Miller and Andrew Millard about aborigenes and pottery in cooking.
> Obviously cooking affects
> digestibility and/or assimilation, or we wouldn't do it in the case of
> grains and tubers, to mention two items; and obviously many people in
> today's world exist most of their lives on mostly cooked food. So to me in
> most cases it seems like more a question of degrees and gradations of
> digestibility, not either/or.
You are right. There is a difference between pre-cooking toxicity from efficient plant anti-nutritional
factors which can kill very fast (e.g. lectins from 5-8 Ricinus beans, or cyanogens from manihot are enough to
kill an adult overnight; for wheat anti-nutritional factors, weaker poisonous activities selected for 100s of
years require a few more days to kill an adult), and post-cooking toxicity arising from over-cooked (or burnt)
foods, and containing man-made carcinogens. These latters are rather slow-killers, requiring more time to kill
someone than plant anti-nutritional factors.
> >As an example, can I digest cooked starch because my ancestors ate raw
> >starch foods in pre-fire days, and the chemical composition is
> >altered some, but not that much, by cooking?
Cooking does two things for starch : on the one hand, it modifies its physical (not chemical) properties, i.e.
once at 68-72°C, it gelatinzes the starch granules, hence rendering them hydrolysable by alpha-amylases; and
on the other hand, cooking inactivates anti-amylase activities of plant anti-nutritional factors (e.g. in wheat
two thirds of the albumins, i.e. water soluble proteins, have anti-amylase activities).
>
> Well, this question of course presupposes there wasn't any cooking in
> prehistoric times for a long enough time to have affected the human genome,
If ever affected, the human genome must have been affected BEFORE cooking. Indeed, all animals fear the fire.
Only humans have "domesticated" it. All animals that I know, whether birds, turtles, cats, dogs rabbits,
horses, etc, love to eat a piece of bread or of chocolate or of cooked potato, when given the opportunity. The
major difference between animals and humans is that only humans can cook potatos, bake a bread or roast cocoa
beans before manufacturing any piece of chocolate or of food. Without mastering of the Fire Technology, there
would have been no invention of the cooking process. This suggests that that fire and cooking technologies may
have arisen thank to a genetic defect, a defect which allowed humans "to experiment and to play" with the fire;
a defect which does not look fixed as yet...
> and there may have in fact been--these days I am not convinced by what
> evidence is available one way or the other.
What evidence do you refer to? - If you want, I can refer you to more convincing evidences published in other
scientific disciplines. (I just reviewed 188 of them, but the list itself is too long for an email).
> However, supposing for the
> moment that were the case (no adaptation to cooking yet),
There may have been no need "to adapt" to cooking. Rather, recent studies on Plant-Food-Consumer Interactions
suggest that there may have been a need to adapt to changing environmental conditions and increased competitive
pressures, forcing humans (and other mammals) either to starve from hunger, or to find a way to enhance calorie
intake, while at the same time overcoming plant anti-nutritional factors. As stated above, our ancestors seem
to have achieved this maybe thank to a genetic defect unique to humans.
> I would tend to
> think so (that the starch is digestible to what degree it is cooked based
> on prior adaptations to raw starch). However, the kicker here is that from
> what I understand, the starch in many root veggies and probably all grains
> is much MORE digestible when cooked.
As said above, at the end of proper cooking, no more active anti-amylase coupled to starch gelatinization, that
is an enhancement of both food safety and nutritional properties, for the benefit of plant/grain-eaters.
>
> So the sword can cut both ways here, and when it cuts this latter way, it
> sort of begs the question of how certain cooked foods could be more
> digestible than raw if we hadn't encountered those cooked foods in
> evolution before. The two possible answers would seem to be that: (1) we
> HAVE encountered those foods cooked before and made more successful use of
> them cooked than raw,
Around the World, we still keep improving their cooking today.
> or (2) we HAVEN'T encountered those foods, and we
> aren't that well-adapted to them raw, but for whatever reason cooking
> renders them--by fortuitous circumstance--more digestible given our
> previously evolved digestive mechanisms.
Plants seem to have evolved an ability to biosynthesize anti-nutritional factors in response to over-feeding by
phytophagous predators. In their turn, grain eating-birds and insects evolved digestive biochemical mechanism
to overcome these new plant anti-nutritional factors. Not humans! The latter may have benefited from a
genetic defect allowing them not to have any fear from the fire, hence opening the way to human specific
cooking/detoxifying technology. The formers (birds and insects) may have benefited from a genetic advantage,
i.e. in their stomach, they have a pH of 4, versus 1.5 for the humans. At pH 4, toxic plant proteins with
anti-nutritional activities precipitate (isoelectric pH), hence anihilating poisonous action without any need
for the fire technology...
>
> >Is grain close enough in chemical composition to say, tubers, that we
> >can digest it OK?
Starch granules may look somewhat different in size, and in side-chains between grains and tubers, but
ultimately, all starch granules, whatever their source (tubers, grains or beans) are all composed solely of
glucose units. Some proteins, as the wheat friabilins, may be attached to granules, but they are not part of
starch granules.
> >Is dairy close enough in chemical composition to other foods (that is,
> >it is similar to an average of meat + fruit, hence within the "range" of
> >digestible "original" foods), that many of us can digest it?
As a matter of fact, and from the energy (calories) angle of approach, human mother milk is fairly close to
milk chocolate, the latter being (a lot) more concentrated than the former, or the former being (a lot) more
diluted (high water content) than the latter.
> And answering to a question of Ward's second message by another question:
>
> At the request of a friend of mine on the Raw-Food listgroup, I'm posting a
> few questions here that he put to me on the subject of cooked vs. raw-food
> digestibility, in the hopes that someone with a technical background here
> will have answers. (References would also be nice, and score you
> bragging-rights bonus points. :-) )
Are you sure that you desire references ? - There are so many around.
> Note that those in the all-raw-foodist
> camp are intensely skeptical of any reasoning or data that might support
> the cooking of food in any way, so should you have something along those
> lines, references would be most appreciated where you have them. (Same goes
> for opposing views of course, as well.)
Sounds like a group knowing what fun means, doesn't it?
> Are cooked foods close enough in composition to their raw counterpart that
> we can digest them anyway (as we are omnivores, able to digest a
> wide variety of foods and survive on radically different diets)? As
> an example, can I digest cooked starch because my ancestors ate raw
> starch foods in pre-fire days, and the chemical composition is
> altered some, but not that much, by cooking?
As stated above, sorry to repeat : NO! - Upon cooking, you can digest grain and bean starch because seed
anti-amylases have been inactivated. And you can digest banana starch without cooking. Bananas do not contain
any anti-amylase activity : they are fruits, not seeds. (Indeed, in terms of plant life, fruits and seeds do
not have the same biological function).
That was long enough for this answer. Have a good day and "raw" food regards from the Kingdom of Belgium,
Luc
--
Luc De Bry, Ph.D., Head of Research Department
GENERAL BISCUITS BELGIE
De Beukelaer-Pareinlaan 1
B-2200 Herentals - Belgium
Tel 32 (0)14 24 14 32
Fax 32 (0)14 24 10 25
Email : [log in to unmask]
An Operating Company of http://www.danonegroup.com
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Views expressed above are from the author, according to his today's limited knowledge, and not necessarily from
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