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Oils in Context
by Raymond Peat. Ph.D.
An oil
researcher[0] spent 100 days eating what he considered to be the
Eskimo diet, seal blubber and mackerel paste. He observed that
his blood lipid peroxides (measured as malondialdehyde, MDA)
reached a level 50 times higher than normal, and although MDA is
teratogenic, he said he wasn't worried about fathering deformed
children, because his sperm count had gone to zero. Evidently, he
didn't have a very thorough understanding of the Eskimo way of
life. In most traditional cultures, the whole animal is used for
food, including the brain and the endocrine glands. Since
unsaturated fats inhibit thyroid function, and since Eskimos
usually have a high caloric intake but are not typically obese, it
seems that` their metabolic rate is being promoted by something in
their diet, which might also be responsible for protecting them
from the effects experienced by the oil researcher. (According to
G. W. Crile, the basal metabolic rate of Eskimos was 125% of that
of people in the United States.)
People who eat
fish heads (or other animal heads) generally consume the thyroid
gland, as well as the brain. The brain is the body's richest
source of cholesterol, which, with adequate thyroid hormone and
vitamin A, is converted into the steroid hormones pregnenolone,
progesterone, and DHEA, in proportion to the quantity circulating
in blood in low-density lipoproteins. The brain is also the
richest source of these very water-insoluble (hydrophobic) steroid
hormones; it has a concentration about 20 times higher than the
serum, for example. The active thyroid hormone is also
concentrated many-fold in the brain.
DHEA (dehydroepiandrosterone)
is known to be low in people who are susceptible to heart disease
[1] or cancer, and all three of these steroids have a broad
spectrum of protective actions. Thyroid hormone, vitamin A, and
cholesterol, which are used to produce the protective steroids,
have been found to have a similarly broad range of protective
effects, even when used singly. For example, according to
MacCallum,
It has been shown
that certain lipoid substances, especially cholesterine, can act
as inhibiting or neutralizing agents toward such haemolytic
poisons as saponin, cobra poison, etc., through forming with them
an innocuous compound. Hanes showed that the relative immunity of
puppies from chloroform poisoning is due to the large amount of
cholesterin esters in their tissues. When artificially introduced
into the tissues of adult animals a similar protection is
conferred.[2]
A high level of
serum cholesterol is practically diagnostic of hypothyroidism, and
can be seen as an adaptive attempt to maintain adequate production
of the protective steroids. Broda Barnes work clearly showed that
hypothyroid populations are susceptible to infections, heart
disease, and cancer. [3]
In the 1940s, some of the toxic effects of fish oil (such as
testicular degeneration, softening of the brain, muscle damage,
and spontaneous cancer) were found to result from an induced
vitamin E deficiency. Unfortunately, there isn't much reason to
think that just supplementing vitamin E will provide general
protection against the unsaturated fats. The half-life of fats in
human adipose tissue is about 600 days, meaning that significant
amounts of previously
consumed oils will
still be present up to four years after they have been removed
from the diet. [4] According to Draper, et al., [5]
,
, ,
enrichment of the tissues with highly unsaturated fatty acids
results in an increase in lipid peroxidation in vivo even in the
presence of normal concentrations of vitamin E. Fasting for more
than 24 hours also results in an increase in MDA excretion,
implying that lipolysis is associated with peroxidation of the
fatty acids released.
According to
Lemeshko, et al., it seems that this effect increases with the age
of the animal. [6]
Commercial
advertising (including medical conferences sponsored by
pharmaceutical companies) and commercially sponsored research are
creating some false impressions about the role of unsaturated oils
in the diet. Like the man who poisoned himself with the Eskimo
diet, many people focus so intently on avoiding one problem that
they create other problems. Since I have discussed the
association of unsaturated fats with aging, lipofuscin, and
estrogen elsewhere, I will outline some of the other problems
associated with the oils, especially as they relate to hormones.
Mechanisms and
Essentiality:
When something is
unavoidable, in ordinary life, talking about essentiality, or the
minimum amount required for life or for optimal health, is more
important as an exploration into the nature of our life than as a
practical health issue. For example, how much oxygen, how many
germs (of what kinds), how many cosmic rays (of what kinds), would
produce the nicest human beings? The fact that we have adapted to
something--oxygen at sea level, microbes, or vegetable fats, for
example--doesn't mean that we are normally exposed to it in ideal
amounts.
Animals contain desaturase enzymes, and are able to produce
specific unsaturated fats (from oleic and palmitoleic acids) when
deprived of the ordinary essential fatty acids, [7] so it can be
assumed that these enzymes have a vital purpose. The high
concentration of unsaturated fats in mitochondria--the respiratory
organelles where it seems that these lipids present a special
danger of destructive oxidation--suggests that they are required
for mitochondrial structure, or function, or regulation, or
reproduction. Unsaturated fats have special properties of
adsorption, [8] and are more soluble in water than are saturated
fats. The movement and modulation of proteins and nucleic acids
might require these special properties. As the main site of ATP
production, I suspect that their water-retaining property might be
crucial. When a protein solution (even egg-white) is poured into
a high concentration of ATP, it contracts or superprecipitates.
This condensing, water-expelling property of ATP in protein
solutions is similar to the effect of certain concentrations of
salts on any polymer. It would seem appropriate to have a
substance to oppose this condensing effect, to stimulate swelling
[9, 10] and the uptake of precursor substances. Something that
has an intrinsic structure-loosening or water-retaining effect
would be needed. The ideas of chaotropic agents and structural
antioxidants have been proposed by Vladimirov [11] to bring
generality into our understanding of the mitochondria. Lipid
peroxides are among the chaotropic agents, and thyroxin is among
the structural antioxidants. The known oxygen-sparing effects of
progesterone [12, 13] would make it appropriate to include it
among the
structural antioxidants. The incorporation of the wrong
unsaturated fats into mitochondria would be expected to damage the
vital respiratory functions.
Some insects that
have been studied have been found not to require the essential
fatty acids. [14]* According to reviewers, hogs and humans have
not been shown to require the essential fatty acids. [15] In
vitro studies indicate that they are not required for human
diploid cells to continue dividing in culture. [16] According to
Guarnieri, [17] EFA-deficient animals don't die from their
deficiency. The early studies showing essentiality of unsaturated
fats, by producing skin problems and an increased metabolic rate,
have been criticized [18] in the light of better nutritional
information, e.g., pointing out that the diets might have been
deficient in vitamin B6 and/or biotin. The similar skin condition
produced by vitamin B6 deficiency was found to be improved by
adding unsaturated fats to the diet. A fat-free liver extract
cured the EFA deficiency. I think it would be reasonable to
investigate the question of the increased metabolic rate produced
by a diet lacking unsaturated fats (which inhibit both thyroid
function and protein metabolism) in relation to the biological
changes that have been observed. Since diets rich in protein are
known to increase the requirement for vitamin B6 [19] (which is a
co-factor of transaminases, for example), the increased rate of
energy production and improved digestibility of dietary protein on
a diet lacking unsaturated fats would certainly make it reasonable
to provide the experimental animals with increased amount of other
nutrients. With increasing knowledge, the old experiments
indicating the essentiality of certain oils have lost their
ability to convince, and they haven't been replaced by new and
meaningful demonstrations. In the present state of knowledge, I
don't think it would be unreasonable to suggest that the optional
dietary level of the essential fatty acids might be close to zero,
if other dietary factors were also optimized. The practical
question, though, has to do with the dietary choices that can be
made at the present time.
In evaluating
dietary fat, it is too often forgotten that the animals diet (and
other factors, including temperature) affect the degree of
saturation of fats in its tissues, or its milk, or eggs. The fat
of wild rabbits or summer-grazing horses, for example, can contain
40% linolenic acid, about the same as linseed oil. Hogs fed
soybeans can have fat containing over 30% linoleic acid. [20]
Considering that most of our food animals are fed large amounts of
grains and soybeans, it isn't accurate to speak of their fats as
"animal fats." And, considering the vegetable oil contained in our
milk, eggs, and meat, it would seem logical to select other foods
that are not rich in unsaturated oils.
Temperature
and Fat:
The fact that saturated fats are dominant in tropical plants and
in warm-blooded animals relates to the stability of these oils at
high temperatures. Coconut oil which had been stored at room
temperature for a year was found to have no measurable rancidity.
Since growing coconuts often experience temperatures around 100
degrees Fahrenheit, ordinary room temperature isn't an oxidative
challenge. Fish oil or safflower oil, though, can't be stored
long at room temperature, and at 98 degrees F, the spontaneous
oxidation is very fast.
Bacteria vary the
kind of fat they synthesize, according to temperature, forming
more saturated fats at higher temperatures.[21] The same thing
has been observed in seed oil plants. [22] Although sheep have
highly saturated fat, the superficial fat near their skin is
relatively unsaturated; it would obviously be inconvenient for the
sheep if their surface fat hardened in cool weather, when their
skin temperature drops considerably. Pigs wearing sweaters were
found to have more saturated fat than other pigs.[23] Fish, which
often live in water which is only a few degrees above freezing,
couldn't function with hardened fat. At temperatures which are
normal for fish, and for seeds which germinate in the cold
northern springtime, rancidity of fats isn't a problem, but
rigidity would be.
Unsaturated
Fats Are Essentially Involved In Heart Damage:
The toxicity of
unsaturated oils for the heart is well established, [24, 25, 26]
though not well known by the public.
In 1962, it was
found that unsaturated fatty acids are directly toxic to
mitochondria. [27] Since stress increases the amount of free
fatty acids circulating in the blood (as well as lipid peroxides),
and since lack of oxygen increases the intracellular concentration
of free fatty acids, stored unsaturated fats would seem to
represent a special danger to the stressed organism. Meerson and
his colleagues [18] have demonstrated that stress liberates even
local tissue fats in the heart during stress, and that systematic
drug treatment, including antioxidants, can stop the enlargement
of stress-induced infarctions. Recently, it was found that the
cardiac necrosis caused by unsaturated fats (linolenic acid, in
particular) could be prevented by a cocoa butter supplement. [29]
The author suggests that this is evidence for the essentiality of
saturated fats, but points out that animals normally can produce
enough saturated fat from dietary carbohydrate or protein, to
prevent cardiac necrosis, unless the diet provides too much
unsaturated fat. A certain proportion of saturated fat appears to
be necessary for stability of the mitochondria. Several other
recent studies show that the essential fatty acids decrease the
P/O ratio, or the phosphorylation efficiency, [30] the amount of
usable energy produced by cellular respiration.
There has been
some publicity about a certain unsaturated fat, eicosapentaenoic
acid, or EPA, which can have some apparently protective and
anti-inflammatory effects. A study in which butter was added to
the animals diet found that serum EPA was elevated by the butter.
The investigator pointed out that other studies had been able to
show increased serum EPA from an EPA supplement only when the
animals had previously been fed butter. [31]
Intense lobbying
by the soybean oil industry has created the widespread belief that
tropical oils cause heart disease. In a comparison of many kinds
of oil, including linseed oil, olive oil, whale oil, etc., palm
oil appeared to be the most protective. The same researcher [32]
more recently studied palm oils antithrombotic effect, in relation
to platelet aggregation. It was found that platelet aggregation
was enhanced by sunflowerseed oil, but that palm oil tended to
decrease it.
Much current research has concentrated on the factors involved in
arterial clotting. Since the blood moves quickly through the
arteries, rapid processes are of most interest to those workers,
though some
people do remember to think in terms of an equilibrium between
formation and removal of clot material. For about 25 years there
was interest in the ability of vitamin E to facilitate clot
removal, apparently by activating proteolytic enzymes.[33]
Unsaturated fats ability to inhibit proteolytic enzymes in the
blood has occasionally been discussed, but seldom in the U.S. The
equilibrium between clotting and clot dissolution is especially
important in the veins, where blood moves more slowly, and spends
more time.
.
. . the
slower blood flows the greater its predisposition to clotting.
However, this intrinsic process, leading to fibrin production, is
slow, taking up to a minute or more to occur. Thrombosis as a
result of stasis, therefore, occurs in the venous circulation;
typically in the legs where venous return is slowest. In fact,
many thousands of small thrombi are formed each day in the lower
body. These pass via the vena cava into the lungs where
thrombolysis occurs, this being a normal metabolic function of the
organ. [34]
In the Shutes
research in the 1930s and 1940s, vitamin E and estrogen acted in
opposite directions on the clot-removing enzymes.[33] Since
estrogen increases blood lipids, and increases the incidence of
strokes and heart attacks, it would be interesting to expand the
Shutes work by considering the degree of saturation of blood
lipids in relation to the effects of vitamin E and estrogen on
clot removal. Estrogen's effect on clotting is very complex,
since it increases the ratio of unsaturated to saturated fatty
acids in the body, and increases the tendency of blood to pool in
the large veins, in addition to its direct effects on the clotting
factors.
Immunodeficiency and Unsaturated Fats:
Intravenous
feeding with unsaturated fats is powerfully immunosuppressive [35]
(though it often was used to give more calories to cancer
patients) and is now advocated as a way to prevent graft
rejection. The deadly effect of the long-chain unsaturated fats
on the immune system has led to the development of new products
containing short and medium-chain saturated fats for intravenous
feeding. [36] It was recently reported that the anti-inflammatory
effect of n-3 fatty acids (fish oil) might be related to the
observed suppression of interleukin-1 and tumor necrosis factor by
those fats. [37] The suppression of these anti-tumor immune
factors persists after the fish oil treatment is stopped.
As mentioned
above, stress and hypoxia can cause cells to take up large amounts
of fatty acids. Cortisols ability to kill white blood cells
(which can be inhibited by extra glucose) is undoubtedly an
important part of its immunosuppressive effect, and this killing
is mediated by causing the cells to take up unsaturated fats. [38]
Several aspects of
the immune system are improved by short-chain saturated fats.
Their anti-histamine action [39] is probably important, because of
histamines immunosuppressive effects.[40] Unsaturated fats have
been found to cause degranulation of mast cells.[41] The
short-chain fatty acids normally produced by bacteria in the bowel
apparently have a local anti-inflammatory action.[42]
A recent
discussion of tissue destruction by neutrophils mentions a
fascinating series of experiments performed between 1888 and 1906,
in which German and American scientists established the importance
of neutrophil proteinases and plasma antiproteinases in the
evolution of tissue damage in vivo. [43] MacCallums Pathology
described some related work:
.
. .
Jobling has shown that the decomposition products of some fats--
unsaturated fatty acids and their soaps--have the most decisive
inhibiting action upon proteolytic ferments, their power being in
a sense proportional to the degree of unsaturation of the fatty
acid. So universally is it true that such unsaturated fatty acids
can impede the action of proteolytic ferments that many
pathological conditions (such as the persistence of caseous
tuberculous material in its solid form) can be shown to be due to
their presence. If they are rendered impotent by saturation of
their unsaturated group with iodine, the proteolysis goes on
rapidly and the caseous tubercle or gumma rapidly softens.[44]
Another comment
by MacCallum suggests one way in which unsaturated fats could
block the action of cytotoxic cells:
This function of
the wandering cells is, of course, of immediate importance in
connection with their task of cleaning up the injured area to
prepare it for repair. While the proteases thus produced are
active in the solution of undesirable material, their unbridled
action might be detrimental. As a matter of fact, it is shown by
Jobling and Petersen that the anti-ferment known to be present in
the serum and to restrict the action of the ferment is a
recognizable chemical substance, usually a soap or other
combination of an unsaturated fatty acid. It is possible to
remove or decompose this substance or to saturate the fatty acid
with iodine and thus release the ferment to its full activity.
[45]
Unsaturated
Fats Are Essential For Cancer:
The inhibition of
proteolytic enzymes by unsaturated fats will act at many sites:
digestion of protein, digestion of clots, digestion of the colloid
in the thyroid gland which releases the hormones, the activity of
white cells mentioned above, and the normal digestion of
cytoplasmic proteins involved in maintaining a steady state as new
proteins are formed and added to the cytoplasm. It has been
suggested that inhibition of the destruction of intracellular
proteins would shift the balance toward growth.[46] Cancer cells
are known to have a high level of unsaturated fats,[47] yet they
have a low level of lipid peroxidation;[48] lipid peroxidation
inhibits growth, and is often mentioned as a normal growth
restraining factor.[49]
In 1927, it was observed that a diet lacking fats prevented the
development of spontaneous tumors.[50] Many subsequent
investigators have observed that the unsaturated fats are
essential for the development of tumors. [51, 52, 53] Tumors
secrete a factor which mobilizes fats from storage, [54]
presumably guaranteeing their supply in abundance until the
adipose tissues are depleted. Saturated fats, coconut oil and
butter, for example do not promote tumor growth.[55] Olive oil is
not a strong tumor promoter, but in some experiments it does have
a slightly permissive effect on tumor growth. [56, 57] In some
experiments, the carcinogenic action of unsaturated fats could be
offset by added thyroid, [57] an observation which might suggest
that at least part of the effect of the oil is to inhibit
thyroid. Adding cystine to the diet (cysteine, the reduced form
of cystine, is a thyroid antagonist) also increases the tumor
incidence.[58] In a hyperthyroid state, the ability to quickly
oxidize larger amounts of the toxic oils would very likely
have a protective
effect, preventing storage and subsequent peroxidation, and
reducing the oils ability to synergize with estrogen.
Consumption of
unsaturated fat has been associated with both skin aging and with
the sensitivity of the skin to ultraviolet damage, Ultraviolet
light-induced skin cancer seems to be mediated by unsaturated fats
and lipid peroxidation.[59]
In a detailed
study of the carcinogenicity of different quantities of
unsaturated fat, Ip, et al., tested levels ranging from 0.5% to
10%, and found that the cancer incidence varied with the amount of
essential oils in the diet. Some of their graphs make the point
very clearly: [52}
This suggests
that the optimal EFA intake might be 0.5% or less.
Butter and coconut
oil contain significant amounts of the short and medium-chain
saturated fatty acids, which are very easily metabolized,[60]
inhibit the release of histamine,[39] promote differentiation of
cancer cells,[61] tend to counteract the stress-induced
proteins,[62] decrease the expression of prolactin receptors, and
promote the expression of the T3 (thyroid) receptor. [63] (A
defect of the thyroid receptor molecule has been identified as an
oncogene, responsible for some cancers, as has a defect in the
progesterone receptor.)
Besides inhibiting
the thyroid gland, the unsaturated fats impair intercellular
communication,[64] suppress several immune functions that relate
to cancer, and are present at high concentrations in cancer cells,
where their antiproteolytic action would be expected to interfere
with the proteolytic enzymes and to shift the equilibrium toward
growth. In the free fatty acid form, the unsaturated fats are
toxic to the mitochondria, but cancer cells are famous for their
compensatory glycolysis.
By using lethargic
connective tissue cells known to have a very low propensity to
take up unsaturated fats [65] as controls in comparison with,
e.g., breast cancer cells, with a high affinity for fats, it is
possible to show a selective toxicity of oils for cancer cells.
However, an in vivo test of an alph-linolenic acid ester showed it
to have a stimulating effect on breast cancer.[66] Given a
choice, skin fibroblasts demonstrate a very specific preference
for oleic acid, over a polyunsaturated fat.[67]
Even if
unsaturated fats were (contrary to the best evidence) selectively
toxic for cancer cells, their use in cancer chemotherapy would
have to deal with the issues of their tendency to cause pulmonary
embolism,their suppression of immunity including factors
specifically involved in cancer resistance, and their
carcinogenicity.
Brain Damage
And Lipid Peroxidation:
When pregnant
mice were fed either coconut oil or unsaturated seed oil, the mice
that got coconut oil had babies with normal brains and
intelligence, but the mice exposed to the unsaturated oil had
smaller brains, and had inferior intelligence. In another
experiment, radioactively labeled soy oil was given to nursing
rats, and it was shown to be massively incorporated into brain
cells, and to cause visible structural changes in the cells. In
1980, shortly after this study was published in Europe, the U.S.
Department of Agriculture issued a recommendation against the use
of soy oil in infant formulas. More recently, [68] pregnant rats
and their offspring were given soy lecithin with their food, and
the exposed offspring developed sensorimotor defects.
Many other studies
have demonstrated that excessive unsaturated dietary fats
interfere with learning and behavior, [70, 71] and the fact that
some of the effects can be reduced with antioxidants suggests that
lipid peroxidation causes some of the damage. Other studies are
investigating the involvement of lipid peroxidation in
seizures.[72]
The past use of
soy oil in artificial milk (and in maternal diets) has probably
caused some brain damage. The high incidence of neurological
defects (e.g., 90%) that has been found among violent criminals
suggests that it might be worthwhile to look for unusual patterns
of brain lipids in violent people.
There have been a
series of claims that babies brains or eyes develop better when
their diets are supplemented with certain unsaturated oils, based
on the idea that diets may be deficient in certain types of oil,
Some experimenters claim that the supplements have improved the
mental development of babies, but other researchers find that the
supplemented babies have poorer mental development. But the oils
that are added to the babies diets are derived from fish or algae,
and contain a great variety of substances (such as vitamins) other
than the unsaturated fatty acids, and the researchers consistently
fail to control for the effects of such substances.
It has shown that
it is probably impossible to experience a detectable deficiency of
linoleic acid outside of the laboratory setting,[69] but the real
issue is probably whether the amount in the normal diet is harmful
to development. Until the research with animals has produced a
better understanding of the effects of unsaturated oils,
experimenting on human babies seems hard to justify.
Marion Diamond,
who has studied the improved brain growth in rats given a
stimulating environment (which, like prenatal progesterone,
produced improved intelligence and larger brains), observed that
in old age the enriched rats brains contained less lipofuscin (age
pigment).[73] It is generally agreed that the unsaturated oils
promote the formation of age pigment. The discovery that stress
or additional cortisone (which, by blocking the use of glucose,
forces cells to take up more fat) causes accelerated aging of the
brain[74] should provide new motivation to investigate the
antistress properties of substances such as the protective
steroids mentioned above, and the short-chain saturated fats.
Essential for
Liver Damage:
Both experimental and epidemiological studies have shown that
dietary linoleic acid is required for the development of alcoholic
liver damage.[75] Animals fed tallow and ethanol had no liver
injury, but even 0.7% or 2.5% linoleic acid with ethanol caused
fatty liver, necrosis, and inflammation. Dietary cholesterol at a
level of 2% was found to cause no harm,[76] but omitting it
entirely from the diet caused leakage of amino-transferase
enzymes. This effect of the absence of cholesterol was very
similar to the effects of the presence of linoleic acid with
ethanol.
Obesity:
For
many years studies have been demonstrating that dietary coconut
oil causes decreased fat synthesis and storage, when compared with
diets containing unsaturated fats. More recently, this effect has
been discussed as a possible treatment for obesity.[77] The
short-chain fats in coconut oil probably improve tissue response
to the thyroid hormone (T3), and its low content of unsaturated
fats might allow a more nearly optimal function of the thyroid
gland and of mitochondria. A survey of other tropical fruits
content of short and medium chain fatty acids might be useful, to
find lower calorie foods which contain significant amounts of the
shorter-chain fats.
Other Problem
Areas:
The presence of palmitate in the lung surfactant
phospholipids[78] suggests that maternal overload with unsaturated
fats might interfere with the formation of these important
substances, causing breathing problems in the newborn. The
bone-calcium mobilizing effect of prostaglandins suggests that
dietary fats might affect osteoporosis; the absence of
osteoporosis in some tropical populations might relate to their
consumption of coconut oil and other saturated tropical oils. The
steroids which occur in association with some seed oils might be
nutritionally significant, in the way animal hormones in foods
undoubtedly are. For example, soy steroids can be converted by
bowel bacteria into estrogens. R. Marker, et al., found diosgenin
(the material in the Mexican yam from which progesterone, etc.,
are derived) in a palm kernel, Balanites aegyptica (Wall).[79]
Another palm fruit also contains sterols with anti-androgenic and
anti-edematous actions.[80, 81]
If the amount of
ingested unsaturated fats (inhibitors of protein digestion) were
lower, protein requirements might be lower.
The similar
effects of estrogen and of polyunsaturated fats (PUFA) are
numerous. They include antagonism to vitamin E and thyroid, to
respiration and proteolysis; promotion of lipofuscin formation and
of clot formation, promotion of seizure activity, impairment of
brain development and learning; and involvement in positive or
negative regulation of cell division, depending on cell type.
These parallels
suggest that the role of PUFA in reproduction might be similar to
that of estrogen, namely, the promotion of uterine and breast cell
proliferation, water uptake, etc. Such parallels should be a
caution in generalizing from the conditions which are essential
for reproduction to the conditions which are compatible with full
development and full functional capacity. If a certain small
amount of dietary PUFA is essential for reproduction, but for no
other life function, then it is analogous to the brief estrogen
surge, which must quickly be balanced by opposing hormones. The
present approach to contraception through estrogen-induced
miscarriage might give way to fertility regulation by diet. A
self-actualizing pro-longevity diet, low in PUFA, might prolong
our characteristically human condition of delayed reproductive
maturity, and, if PUFA are really essential for reproduction,
unsaturated vegetable oils could temporarily be added to the diet
when reproduction is desired.
Conclusions:
Polyunsaturated fats are nearly ubiquitous, but if they are
essential nutrients, in the way vitamin A, or lysine, is
essential, that has not been demonstrated. It seems clear that
they are essential for cancer, and that they have other
properties which cause them to be toxic at certain levels. It
might be time to direct research toward determining whether there
is a threshold of toxicity, or whether they are, like ionizing
radiation, toxic at any level.
Note:
A possible
mitochondrial site for toxicity:
In 1971 I was
trying to combine some of the ideas of Albert Szent-Gyorgyi, Otto
Warburg, W. F. Koch, and L. C. Strong. I was interested in the
role of ubiquinone in mitochondrial respiration. In one
experiment, I was using paper chromatography to compare oils that
I had extracted from liver with vitamin E and with commercially
purified ubiquinone. Besides using the pure substances, I decided
to combine vitamin E with ubiquinone for another test spot. As
soon as I combined the two oils, their amber and orange colors
turned to an inky, greenish black color. I tested both bacterial
and mammalian ubiquinone, and benzoquinone, and they all produced
similar colors with vitamin E. When I ran the solvent up the
paper, the vitamin E and the ubiquinone traveled at slightly
different speeds. The black spot, containing the mixture, also
moved, but each substance moved at its own speed, and as the
materials separated, their original lighter colors reappeared.
Charge-transfer bonds, which characteristically produce dark
colors, are very weak bonds. I think this must have been that
kind of bond. Years later, I tried to repeat the experiment,
using ubiquinone from various capsules that were sold for medical
use. Instead of the waxy yellow-orange material I had used
before, these capsules contained a liquid oil with a somewhat
yellow color. Very likely, the ubiquinone was dissolved in
vegetable oil. At the time, I was puzzled that the color reaction
didn't occur, but later I realized that a solvent containing
double bonds (e.g., soy oil or other oil containing PUFA) would
very likely prevent the close association between vitamin E and
ubiquinone which is necessary for charge-transfer to occur. Since
I think Koch and Szent-Gyorgyi were right in believing that
electronic activation is the most important feature of the living
state, I think the very specific electronic interaction between
vitamin E and ubiquinone must play an important role in the
respiratory function of ubiquinone. Ubiquinone is known to be a
part of the electron transport chain which can leak electrons, so
this might be one of the ways in which vitamin E can prevent the
formation of toxic free-radicals. If it can prevent the leakage
of electrons, then this in itself would improve respiratory
efficiency. If unsaturated oils interfere with this very specific
but delicate bond, then this could explain, at least partly, their
toxicity for mitochondria. [Electron leak reference: B.
Halliwell, in Age Pigments (R. S. Sohal, ed.), pp. 1-62,
Elsevier, Amsterdam, 1981.]
*If we followed
Linus Paulings reasoning in determining optimal vitamin C
intake, this study of the linoleic acid content of the tissues
of an animal which can synthesize it would suggest that we are
eating about 100 times more EFA than we should.
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