Since the book of Howell ("Enzyme nutrition", abridged by Viktoras Kulvinkas
under the title "Food Enzymes for Health and Longevity") has been mentioned, I
would like to revisit the question and give my comments on the claims of the
author. You can find a review of the book by Bob Avery on the rawtimes homepage

http://www.rawtimes.com/b-howell-avery.html

CLAIM: Enzymes are not merely catalysts. They contain the life force, which is
immaterial. Once the enzyme potential has been used up, we die. Therefore,
preserving our enzyme potential will ensure longevity.

COMMENT: If the author starts with such assumptions, one may question the
scientific value of his reasonings. Enzymes *are* catalysts, in the broad sense
(i.e. they speed up a chemical reaction, or allow a barrier of potential to be
crossed, and are left unchanged after the reaction has occurred). The mode of
action of various enzymes has been described by scientists, there is nothing
mysterious. Enzymes are not the life force, and the idea that we have a certain
"quantity of life" at birth, and that by eating "living foods" we can increase
our life potential (or at least preserve it) is naive and unproven. No one has
ever measured any enzyme potential (in the sense that Howell understands it),
and, according to modern theories of aging, telomere length, rather than
enzymes, are the main reason for the process of aging.

CLAIM: Food enzymes act in the mouth and in the upper stomach, before our own
enzymes have begun to digest the food. A few enzymes are left undestroyed by the
stomach acids and are absorbed by the intestine. Thus, eating raw food will
preserve the enzyme potential.

COMMENT: Certainly cooking destroys enzymes, but may improve digestibility for
another reason. And again, the existence of the enzyme potential is dubious.
Finally, enzymes are recycled after use. There is no proof that raw food
requires less enzymes to be digested.

CLAIM: Humans have a larger pancreas than herbivores (per unit of body weight).
It seems by comparing different human populations that people eating more
heat-treated carbohydrates (i.e. cooked starch) have a larger pancreas and
larger salivary glands.

COMMENT: One can't compare humans and herbivores. Probably other organs than
pancreas have a different size. As for the comparison between different human
populations, a larger pancreas and larger salivary glands could result from many
other factors than the necessity of producing more enzymes. In particular, it
could be that eating more carbohydrates increases the secretion of insulin [Side
note: several abnormalities of salivary glands in diabetics have been observed
and studied by scientists]. And even if the increase of size was related to an
increase of amylase production, it's not necessarily pathological. Finally, the
question of starch digestion is probably of minor importance: cooked starch is
pretty easy to digest (humans and cattle are easily "fattened" with cooked
starch), and if one replaces starch by other foods, there would be a need to
produce other enzymes anyway.

CLAIM: Germ-free laboratory animals (not getting any enzymes, neither from food,
nor from intestinal bacteria) are not healthy, but the intestinal track of
arctic animals (who get enzymes from food) is sterile. Therefore, the body can't
produce enough enzymes by itself to sustain health, and so food enzymes are an
important factor for human health.

COMMENT: The "proof" here is incomplete. The only way to complete it would be to
take arctic animals to the lab and feed them an enzyme-free (but not vitamin
deficient) diet. Some animals might need germs (for other reasons than enzyme
production), and others not.

CLAIM: Enzyme secretion is decreased in older people, and some diseases.
Therefore, older people have a practically used up enzyme potential, and people
are sick because of a low enzyme potential.

COMMENT: Here, again, the unproven concept of enzyme potential is used. In older
people, all body functions can impaired, like mental functions. But no one will
say that the "thinking potential" has been used up, and we should exercise our
brain less in order to keep the reserves of thoughts that we inherited at birth!
Same remarks for enzyme secretion in disease.

CLAIM: Continuous loss of pancreatic juice is quickly fatal (dogs die after a
few days). Therefore, it is important for the body to preserve pancreatic
enzymes.

COMMENT: And so? Humans secrete a considerable amount of pancreatic juice every
day (500 to 800 ml), so more than enzymes are lost.

CLAIM: Animals in captivity fed a natural diet are healthier than animals fed a
cooked diet similar to that of humans. Therefore, health suffers from the lack
of food enzymes.

COMMENT: OK, no one doubts that a natural diet is superior, for many reasons
unrelated to enzymes.

CLAIM: Raw milk and raw meat have a higher nutritional value than pasteurized
milk and cooked meat, as shown by comparing the growth rate of rats. Therefore,
food enzymes improve the availability of nutrients.

COMMENT: Cooking affects a food in numerous ways, not only by destroying
enzymes.

CLAIM: Rats fed synthetic diets become sick.

COMMENT: The reference given by Howell is an article by Mc Cay, from the Journal
of Nutrition 10:63-79 (1935). I haven't read it, but I think at that time, all
vitamins and all essential fatty acids hadn't been discovered yet. I happen to
have a copy of Webster's collegiate dictionary, 5th edition (1946), and the
article "Vitamin" only cites the vitamins A, B1 (or F), B2 (or G), B6, C, D, E,
F, L, P. Nowadays, the known vitamins are A, B1 (or thiamine), B2 (or
riboflavin), B3 (or niacin), B5 (or panthotenic acid), B6 (or pyridoxine), B7
(or biotin or H), B9 (or folic acid), B12 (or cobalamin), C, D, E, K.

I don't know what the vitamins L and P from Webster's are.

[Is anyone still reading this?]

Best wishes,

Jean-Louis
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