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<h1>Suitable Fats, Unsuitable Fats: Issues in Nutrition</h1>
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<p class="nav"><span class="nav-left">Listed under <a href="/ray-peat.html">Ray Peat</a>.</span><span class="nav-right"><a href="/theme.html">Theme</a></span></p>
<p>From the <a href="https://raypeat.com/articles/articles/unsuitablefats.shtml" target="_blank">original article</a> in 2007. Author: <a href="https://raypeat.com/" target="_blank">Ray Peat</a>.</p>
<p>For
fifty years, the mass media have been making the public think about
the fats in their diet, filling the culture with clichés about bad
saturated animal fats that raise cholesterol, or lately the trans-fats
in margarine, and images of arteries clogged by bad fats. The public
instruction about the fats we should eat resembles the owner&#39;s manual
for a car, that tells you what kind of motor oil and fuel and coolant
to use; they are telling us that they know how our body works, and that
they know what it needs. But now, even after the human genome has supposedly
been partly &quot;decoded,&quot; the biological functions of the fats
have hardly begun to be investigated.</p>
<p>To
understand the present issues regarding fats in nutrition and medicine
it&#39;s helpful to look at the historical development of biochemical and
physiological fat research in a variety of contexts, including agriculture
and economics, as well as considering the effects of the changing ideas
about cell structure, vitamins, hormones, immunology, brain development,
evolution, and the growing understanding of the way physiology interacts
with ecology. We need to recognize the complexity of the physiology
of fats, to appreciate the complexity of the living organism. </p>
<p>Financial
considerations have driven fat research in very obvious ways. In 1883,
Mark Twain described how commercial fraud was making use of new technology
to substitute cheap fats and oils for butter and olive oil.. Hard fats
such as tallow, which had been used for making soap and candles, began
to be widely used as a substitute for butter in the 19th century. Around
1912, chemists found economical ways to solidify (for use as a butter
substitute) the very cheap liquid oils, such as cottonseed oil, linseed
oil, whale oil, and fish oils, which been used mostly as fuels or varnish.
The seed oils were so cheap that meat packers quickly became major producers
of hydrogenated cottonseed and soy oils, to extend their limited supply
of lard or tallow for sale as shortening or margarine.</p>
<p>Between
1912 and 1927 there were several studies that reported that animals
could live on a fat-free diet, and that in fact they lived longer, and
without the normal mortality from cancer. In the 1940s and 1950s, most
textbooks that mentioned the idea that certain fats were essential nutrients
described it as a controversial idea. But the oil industries used public
relations effectively to sell the medical (heart protective) benefits
of a diet containing increased amounts of linoleic and linolenic acids,
which they called the essential fatty acids. They began citing a 1929
publication (by G. Burr and M. Burr) that claimed to demonstrate the
essentiality of those fatty acids, while ignoring the publications that
pointed in different directions.</p>
<p>The
cheapness of the seed oils led to their use in animal feeds, to promote
growth. By the 1940s, the polyunsaturated oils, including fish oils,
were known to cause deterioration of the brain, muscles, and gonads
in a variety of animals, and this was found to be caused mainly by their
destruction of vitamin E. A little later, the disease called steatitis
or yellow fat disease was found to be produced in various animals that
were fed too much fish or fish oil. </p>
<p>The
reason linseed oil and fish oil were used for making varnishes and paints
was that they are &quot;drying oils,&quot; reacting with oxygen to polymerize
and harden. The physical and chemical propertiess of the oils are fairly
well understood, and among the polyunsaturated fatty acids (PUFA) the
omega -3 fatty acids react most easily with oxygen. Heat, light, and
moisture increase their spontaneous interactions with oxygen, and besides
polymerizing, these oils produce a variety of reactive particles, including
acrolein, which combine with other substances, such as cellular proteins
and DNA, with highly toxic effects. At low temperatures and low oxygen
concentrations these oils are not highly reactive. Fats that harden
at low temperatures (as saturated fats do) wouldn&#39;t be convenient for
organisms that live in a cool environment, and so organisms regulate
the type of fat they synthesize according to the temperature of their
tissues. The fact that certain types of polyunsaturated fatty acids
function nicely in fish, worms, and insects, doesn&#39;t mean that they
are ideal fats for mammals.</p>
<p>The
fact that vitamin E prevented or cured some of the major diseases in
farm animals caused by excessive PUFA, and that it could retard the
development of rancidity in stored oils, led quickly to the persistent
belief that lipid peroxidation is the only toxic effect of the vegetable
oils. However, the oils were being seen to cause other problems, including
accelerated aging and obesity, but those problems weren&#39;t of interest
to farmers, who wanted to sell plump young animals as cheaply and quickly
as possible. Even fresh oils have toxic effects, and the oxidative damage
they do is often the consequence of these other toxic actions.</p>
<p>Another
cheap food additive, coconut oil, was found to increase feed consumption
while slowing weight gain, so it wasn&#39;t popular in the meat industry.
The highly unsaturated seed oils had the opposite effect, of producing
a rapid fattening of the animal, while decreasing feed consumption,
so by 1950 corn and soybeans were widely considered to be optimal feeds
for maximizing profits in the production of meat animals. It was at
this time that the industry found that it could market the liquid oils
directly to consumers, as health-promoting foods, without bothering
to turn them into solid shortening or margarine. Somehow, few physiologists
continued to think about the implications of metabolic slowing, obesity,
and the related degenerative diseases.</p>
<p>As
vitamin research advanced in the 1940s, Roger Williams&#39; lab at the Clayton
Foundation Biochemical Institute, University of Texas at Austin, recognized
the &quot;fat deficiency disease&quot; of the Burrs as a deficiency
of vitamin B6, and showed that when they produced the condition with
a diet similar to the one the Burrs had used, they could cure it by
administering vitamin B6. In the early 1930s George Burr had discovered
that animals on a fat free diet had an extremely high rate of metabolism,
but he didn&#39;t investigate the important ramifications of that observation,
such as their increased need for vitamins and minerals, in accordance
with their rate of metabolism. The PUFA slowed metabolism, and that
effect was good for agriculture.</p>
<p>The
commercial pressure on fat research has created a new way of writing
research reports, that several decades earlier wouldn&#39;t have been acceptable.
For example, the effects of a specific fat on a few of the components
of a complex process such as clotting are often described in the title,
introduction, and conclusion of an article as if they were revealing
a way to prevent heart disease. The effects of unsaturated fats on cells <em>
in vitro</em> are often the opposite of their effects in living animals,
but editors are allowing authors to claim that their <em>in vitro</em>
results justify dietary or therapeutic use of the fats. Journals of
medicine and nutrition are now preferred sites for commercial press
releases, composed to superficially resemble scientific reports.</p>
<p>The
suppressive effects of unsaturated fats on mitochondrial energy production
have been widely investigated, since it is that effect that makes animal
fattening with PUFA so economical. Rather than interpreting that as
a toxic effect, using the innate structure and function of the mitochondrion
as a point of reference from which to evaluate dietary components, the
consumption of &quot;good&quot; oils is being used as the reference
point from which to evaluate the meaning of metabolism (&quot;efficiency
is good,&quot; &quot;low oxygen consumption is good&quot;). Building
on the idea that the oils are health-promoters which increase metabolic
efficiency, the never-viable &quot;rate of aging&quot; theory was resuscitated:
The anti-respiratory effect of PUFA is used (illogically) to return
to the idea that aging occurs in proportion to the amount of oxygen
consumed, because animals which lack the supposedly essential nutrients
(&quot;defective animals&quot;) consume oxygen rapidly--burning calories
rapidly, they are supposed to be like a candle that won&#39;t last as long
if it burns intensely. The old theory is simply resuscitated to explain
why the anti-respiratory action of PUFA might be beneficial, justifying
further promotion of their use as food and drugs.</p>
<p>Ordinarily,
in biochemistry and physiology the inhibition of an enzyme is taken
as a suggestion of toxicity, but when the point of reference is the
idea of the goodness of PUFA, the <em>activity</em> of an intrinsic enzyme
is taken to be evidence of harm, and its <em>inhibition</em> (by PUFA)
is taken to be the proper, healthful situation. The enzyme that produces
the Mead fatty acid is strongly inhibited by PUFA seed oils (less strongly
by fish oils), and so the presence of the Mead acid in the tissues is
taken as evidence that the animal is suffering damage resulting from
the absence of PUFA. The Mead acid happens to have some valuable anti-inflammatory
effects, and is associated with many biological advantages, but research
in that direction is prevented by the lack of funding.</p>
<p>By
1920, the polyunsaturated fatty acids were recognized to inhibit proteolytic
enzymes. At that time, the production of unsaturated fat was considered
to be a feature of certain pathogens, able to overcome the proteolytic-phagocytic
functions of the immune system. </p>
<p>Scattered
studies have found that polyunsaturated fats inhibit the proteolytic
enzymes involved in the digestion of food, in the removal of clots,
in the formation of thyroid hormone, and many other essential physiological
processes. But currently, the only implication being drawn from this
broad class of effects of the PUFA is that some proteolytic enzymes
are involved in disease processes, and consequently increased consumption
of PUFA would be appropriate, because of their ability to suppress a
conditionally harmful proteolytic enzyme. Since the organism consists
mainly of proteins, there are complex innate systems for regulating
the proteolytic enzymes, activating or inactivating them as needed,
and such complexity isn&#39;t likely to depend on variable, unstable dietary
factors. Exogenous substances that inhibit some proteases could create
an unlimited variety of functional and anatomical irregularities.</p>
<p>Some
of the interesting enzymes affected specifically by polyunsaturated
fatty acids are those involved in hormone production. While they inhibit
the formation of progesterone and androgens, they activate the synthesis
of estrogen, which in turn activates the release of more free polyunsaturated
fatty acids from the tissues, in a positive feedback pattern.</p>
<p>The
inhibition of detoxification enzymes by PUFA (Tsoutsikos, et al., 2004)
affects many processes, such as the elimination of estrogen, contributing
to the positive feedback between estrogen and the oils. The meaning
of this tends to be lost, because of the estrogen industry&#39;s effective
campaigns.</p>
<p>Another
situation in which fatty acids participate in a positive feedback system
is the stress reaction, in which the released fatty acids impair mitochondrial
energy production, increasing the stress and leading to further release
of fatty acids.</p>
<p>One
of the perennial theories of aging that has remained viable is the metaplasm/lipofuscin/age
pigment theory, the idea that a toxic material accumulates in tissues
over time. The age pigment contains proteins, cross-linked PUFA, and
metals. The inhibition of proteolytic enzymes is involved in its accumulation,
and the ratio of PUFA to saturated fatty acids is an important factor
in its formation. Estrogen is one of the factors that can promote the
formation of age pigment, probably partly because its lipolytic action
increases the cells&#39; exposure to free fatty acids. The lipofuscin contributes
to inhibition of proteolysis, probably partly through increased production
of free radicals and hydrogen peroxide.</p>
<p>The
proteolytic enzymes are an essential part of innate immunity, and the
highly unsaturated fatty acid, EPA, which is the most immunosuppressive
of the fats, strongly inhibits proteolysis in some cells. The natural
killer (NK) cells and phagocytic cells are two types of cell that are
suppressed by PUFA, and they are involved in many kinds of physiological
events, not just the killing of tumor cells and virus infected cells.</p>
<p>The
immunosuppressive effects of PUFA are very general. Many metabolites
that are known to have harmful effects on the immune system are increased
by the PUFA (histamine [Masini, et al., 1990], serotonin, lactate, nitric
oxide [Omura, et al., 2001]). These substances are also involved in
tumor development.</p>
<p>Besides
inhibiting enzymes and being converted into prostaglandins, the polyunsaturated
fatty acids have direct effects, as signals (or interference with signals)
on many tissues. The belief that the PUFA are essential nutrients has
influenced the way cellular excitability thresholds are being interpreted.
Anxiety and panic may be interpreted as alertness, calmness may be interpreted
as stupidity. Specifically, long-term potentiation (LTP) may contribute
to seizures, senility, and excitotoxicity, as well as to learning, but
many titles and conclusions equate increased LTP with &quot;improved
LTP,&quot; implying that it has biological value to the animal. </p>
<p>The
ability of nerve cells to become quiescent after excitation is essential
to learning and perception. This ability is lost with aging, as the
functional balance in the brain shifts away from GABA-ergic to glutamatergic
nerves. The polyunsaturated fatty acids promote the excitatory nervous
state. The combination of respiratory inhibition with excitation can
produce excitotoxic cell death. If the doctrine of &quot;essentiality
of PUFA&quot; hadn&#39;t been so influential, different interpretations
of excitatory thresholds, energy metabolism, and even cell structure
would have been allowed to develop more fully.</p>
<p>The
concentration of polyunsaturated fats in the brain has led many people
to say that the &quot;nutritionally essential fatty acids,&quot; especially
the omega -3 fatty acids, are essential for brain development (for the
formation of nerve cell membranes), and for the formation of synapses,
and that increasing the amount of those fats in the diet would be desirable.
The types of argument they use simply ignore the real evidence<strong>:</strong>
Cells can multiply indefinitely in culture dishes without the essential
fatty acids, insects can multiply for generations on diets without the
unsaturated fats, forming normal synapses and brains, and mammals fed
diets with extremely small amounts of the unsaturated fats grow with
perfectly normal--possibly superior--brains.</p>
<p>One
of the fats in the omega -9 series, that the human body can synthesize,
nervonic acid, is a major constituent of brain tissue, but its important
functions in brain development have hardly been investigated. Unlike
the unsaturated fatty acids oleic acid, linoleic acid, and eicosapentaenoic
acid (EPA), nervonic acid isn&#39;t associated with the &quot;coronary risk
factors,&quot; and it has been suggested that it might be used in adults
to prevent obesity-related diseases. (Oda, et al., 2005).</p>
<p>One
major area of research that has been neglected involves the role of
fats in modifying the ways in which proteins and nucleic acids interact
with water--arguably the most basic of all physiological processes.
Unsaturated fats are more water soluble than saturated fats, and they
are involved in many problems of permeability and edema.</p>
<p>In
aging and evolution, there are systematic changes in tissue water content
that appear to correspond to changes in rate of metabolism, to the degree
of unsaturation of cellular fats, and to thyroid function and temperature.
Metabolic intensity and longevity can be modified by changing the degree
of saturation of fats in the diet and tissues, but--despite almost a
century of sporadic investigations--no one has yet worked out in detail
the most appropriate way to do this. But it has become clear that the
&quot;uncoupled&quot; mitochondrion, that &quot;wastes oxygen and calories,&quot;
is protective against free radicals, cancer, and aging. Thyroid hormone
and the absence of PUFA are important factors in supporting the &quot;wasteful&quot;
mitochondrion. </p>
<p>Although
the complex interactions of anatomy, energy, temperature, fat nutrition,
tissue water content, and hormones haven&#39;t been systematically investigated,
some of the principles regarding the biological suitability of specific
fats are already being applied in the limited context of therapy. </p>
<p>At
present, the most important issue is to recognize the dangers presented
by the intrusion of corporate power into science, especially as it relates
to nutrition and medicine, and to consider the implications of the known
effects of the PUFA on all of our biological systems.</p>
<p>The
food-derived polyunsaturated fatty acids play important roles in the
development of all of the problems associated with aging--reduced immunity,
insomnia, decreased learning ability, substitution of fat for muscle,
susceptibility to tissue peroxidation and inflammation, growth of tumors,
etc., and are probably involved in most other health problems, even
in children. If research hadn&#39;t been guided by the economic interests
of the seed oil industry, many of those problems would have been solved
by now.</p>
<p>The
influence of the mass media on science can be seen in two issues that
are currently well known. </p>
<p>A
popular test used for evaluating diabetes is the measurement of glycated
hemoglobin, the attachment of a sugar-like fragment to the protein of
hemoglobin. This is used to judge whether blood sugar is being controlled
adequately. The glycation of proteins is widely believed to be a central
process in aging, and is often used to argue that people should reduce
their sugar consumption.</p>
<p>Another
well publicized problem supposedly involving the reaction between sugars
and proteins has to do with the discovery of the carcinogen, acrylamide,
in breads and french fries. The Whole Foods Market was sued in California
for selling whole wheat bread without a warning that it contained a
carcinogen.</p>
<p>But
the changes in proteins that occur in diabetes are mainly produced by
the breakdown products of polyunsaturated fatty acids. Acrylamide is
produced largely by the reaction of PUFA with proteins. </p>
<p>Sugar,
by reducing the level of free fatty acids in the body, actually tends
to protect against these toxic effects of the PUFA. Diabetes, like cancer,
has been known for a long time to be promoted by unsaturated oils in
the diet, rather than by sugar. The seed oil industry has been more
effective than the sugar industry in lobbying and advertising, and the
effects can be seen in the assumptions that shape medical and biological
research. </p>
<h2>References</h2>
<small>
<p>Biochem
Pharmacol. 1990 Mar 1;39(5):879-89. <strong>Histamine release from rat mast
cells induced by metabolic activation of polyunsaturated fatty acids
into free radicals.</strong> Masini E, Palmerani B, Gambassi F, Pistelli
A, Giannella E, Occupati B, Ciuffi M, Sacchi TB, Mannaioni PF.</p>
<p>Int
Heart J. 2005 Nov;46(6):975-85. <strong>Relationships between serum unsaturated
fatty acids and coronary risk factors: negative relations between nervonic
acid and obesity-related risk factors.</strong> Oda E, Hatada K, Kimura J,
Aizawa Y, Thanikachalam PV, Watanabe K. &quot;The objective of the present
study was to analyze the relationships between serum USFA and CRF [coronary
risk factors].&quot; &quot;<strong>Oleic acid (OA), linoleic acid (LA), and
eicosapentaenoic acid (EPA) were positively related to coronary risk
factors (total CRFS = 2, 3, and 4, respectively), while nervonic acid
(NA) exerted negative effects on these risk factors (total CRFS = -6
). It is concluded NA may have preventive effects on obesity-related
metabolic disorders.</strong>&quot;</p>
<p>FEBS
Lett. 2001 Jan 5;487(3):361-6. <strong>Eicosapentaenoic acid (EPA) induces
Ca(2+)-independent activation and translocation of endothelial nitric
oxide synthase and endothelium-dependent vasorelaxation.</strong> Omura M,
Kobayashi S, Mizukami Y, Mogami K, Todoroki-Ikeda N, Miyake T, Matsuzaki
M. &quot;EPA stimulated NO production even in endothelial cells in situ
loaded with a cytosolic Ca(2+) chelator . . . which abolished the [Ca(2+)]i
elevations induced by ATP and EPA.&quot; </p>
<p>Biochem
Pharmacol. 2004 Jan 1;67(1):191-9. <strong>Evidence that unsaturated fatty
acids are potent inhibitors of renal UDP-glucuronosyltransferases (UGT):
kinetic studies using human kidney cortical microsomes and recombinant
UGT1A9 and UGT2B7.</strong> Tsoutsikos P, Miners JO, Stapleton A, Thomas
A, Sallustio BC, Knights KM.</p>
<p>Lipids.
1997 Dec;32(12):1265-70. <strong>Dietary fatty acid profile affects endurance
in rats.</strong> Ayre KJ, Hulbert AJ. &quot;The diets comprised an essential
fatty acid-deficient diet (containing mainly saturated fatty acids);
a diet high in n-6 fatty acids, High n-6; and a diet enriched with n-3
fatty acids, High n-3. Submaximal endurance in rats fed the High n-3
diet was 44% less than in rats fed the High n-6 diet (P &lt; 0.02).
All rats were then fed a standard commercial laboratory diet for a 6-wk
recovery period, and their performances were reevaluated. Although endurance
in all groups was lower then at 9 wk, it was again significantly 50%
lower in the High n-3 group than the High n-6 group (P &lt; 0.005).
Although n-3 fats are considered beneficial for cardiovascular health,
they appear to reduce endurance times, and their side effects need to
be further investigated.&quot;</p>
<p>Ann
Biol Clin (Paris) 2000 Sep-Oct;58(5):595-600.<strong> [Studies on the genotoxic</strong> <strong>
effects of crude liver oils from 3 species of Mediterranean sharks by
means of in vitro micronucleus test using human lymphocytes] </strong>
Bartfai E, Orsiere T, Duffaud F, Villani P, Pompili J, Botta A. &quot;The
results of this experimental study show that the crude liver oils of
three species of sharks are genotoxic and confirm a high carcinogenic
risk.&quot;</p>
<p>Vaccine.
2002 Jan 31;20(9-10):1435-44. <strong>Long-term influence of lipid nutrition
on the induction of CD8(+) responses to viral or bacterial antigens.</strong>
Bassaganya-Riera J, Hontecillas R, Zimmerman DR, Wannemuehler MJ.</p>
<p>J
Nutr. 2001 Sep;131(9):2370-7.<strong> Dietary conjugated linoleic acid modulates
phenotype and effector functions of porcine CD8(+) lymphocytes.</strong>
Bassaganya-Riera J, Hontecillas R, Zimmerman DR, Wannemuehler MJ. </p>
<p>J
Anim Sci, 1984 Apr, 58:4, 971-8. <strong>Essential fatty acid status and
characteristics associated with colostrum-deprived gnotobiotic and conventional
lambs. Growth, organ development, cell membrane integrity and factors
associated with lower bowel function.</strong> Bruckner G; Grunewald KK;
Tucker RE; Mitchell GE Jr &quot;The absence of dietary linoleic acid
decreased liver and spleen weights and, in general, suppressed development
of organs except the brain.&quot; &quot;The results indicate that neonatal
colostrum-deprived lambs have an EFA requirement, as evidenced by decreased
growth and performance characteristics in the GN linoleic deficient
vs GN supplemented group, and suggests that the required level is in
excess of .32% of the total caloric intake as linoleic acid.&quot;</p>
<p>Crit
Care Med. 1996 Jul;24(7):1129-36. <strong>An increase in serum C18 unsaturated
free fatty acids as a predictor of the development of acute respiratory
distress syndrome. </strong>Bursten SL, Federighi DA, Parsons P, Harris WE,
Abraham E, Moore EE Jr, Moore FA, Bianco JA, Singer JW, Repine JE.</p>
<p>Free
Radic Biol Med. 1999 Jul;27(1-2):51-9. <strong>Arachidonic acid interaction
with the mitochondrial electron transport chain promotes reactive oxygen
species generation.</strong> Cocco T, Di Paola M, Papa S, Lorusso M. “It
is shown that arachidonic acid causes an uncoupling effect under state
4 respiration of intact mitochondria as well as a marked inhibition
of uncoupled respiration. While, under our conditions, the uncoupling
effect is independent of the fatty acid species considered, the inhibition
is stronger for unsaturated acids. Experiments carried out with mitochondrial
particles indicated that the arachidonic acid dependent decrease of
the respiratory activity is caused by a selective inhibition of Complex
I and III. It is also shown that arachidonic acid causes a remarkable
increase of hydrogen peroxide production when added to mitochondria
respiring with either pyruvate+malate or succinate as substrate.”</p>
<p>Antioxid
Redox Signal. 2005 Jan-Feb;7(1-2):256-68. <strong>Lipid peroxidation in diabetes
mellitus.</strong> Davi G, Falco A, Patrono C. </p>
<p>Naunyn
Schmiedebergs Arch Pharmacol. 2005 Mar;371(3):202-11. Epub 2005 Apr
15. <strong>Antiarrhythmic and electrophysiological effects of long-chain
omega-3 polyunsaturated fatty acids. </strong>
Dhein S, Michaelis B, Mohr FW. “<strong>Atrioventricular conduction time
was slowed only by DHA and EPA.”</strong> “Regarding antiarrhythmic activity
we found that the <strong>threshold for elicitation of a ventricular extrasystole
was concentration-dependently enhanced by DHA and EPA, but not by ALA.
DHA dose-dependently reduced longitudinal propagation velocity V(L)</strong>
and to a lower extent transverse velocity V(T).” </p>
<p>J
Biol Chem. 2002 Oct 18;277(42):39368-78. <strong>The mechanism of docosahexaenoic
acid-induced phospholipase D activation inhuman lymphocytes involves
exclusion of the enzyme from lipid rafts.</strong> Diaz O, Berquand A, Dubois
M, Di Agostino S, Sette C, Bourgoin S, Lagarde M, Nemoz G, Prigent AF.
“Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid that
inhibits T lymphocyte activation, has been shown to stimulate phospholipase
D (PLD) activity in stimulated human peripheral blood mononuclear cells
(PBMC).” “<strong>This PLD activation might be responsible for the immunosuppressive
effect of DHA because it is known to transmit antiproliferative signals
in lymphoid cells.”</strong></p>
<p>Nutrition.
2003 Feb;19(2):144-9. <strong> Diets rich in polyunsaturated fatty acids:
effect on hepatic metabolism in rats.</strong> Gaiva MH, Couto RC, Oyama
LM, Couto GE, Silveira VL, Ribeiro EB, Nascimento CM. “Male Wistar
rats, just weaned, were fed ad libitum for 8 wk with one of the following
diets: rat chow (C), rat chow containing 15% (w/w) soybean oil (S),
rat chow containing 15% (w/w) fish oil (F), and rat chow containing
15% soy bean and fish oil (SF; 5:1, w/w).” “Body weight gain was
higher in F and SF than in C and S rats. Liver weight, lipid content,
and lipogenesis rate increased in F and SF rats, although adenosine
triphosphate citrate lyase activity decreased. Glycogen concentration
decreased in S, F, and SF rats compared with C rats.” </p>
<p>Br
J Nutr. 2001 Sep;86(3):371-7. <strong>Polyunsaturated fatty acid-rich diets:
effect on adipose tissue metabolism in rats.</strong> Gaiva MH, Couto RC,
Oyama LM, Couto GE, Silveira VL, Riberio EB, Nascimento CM. “Wistar
rats were fed ad libitum, for 8 weeks with one of the following diets:
C, rat chow; S, rat chow containing 15 % (w/w) soyabean oil; F, rat
chow containing 15 % (w/w) fish oil; SF, rat chow containing 15 % (w/w)
soyabean and fish oil (5:1, w/w).” &quot;Energy intake was reduced
while carcass lipid content was increased in the three fat-fed groups.&quot;
&quot;These results indicate that enrichment of the diet with polyunsaturated
fatty acids causes changes in adipose tissue metabolism that favour
fat deposition. Different metabolic pathways were preferentially affected
by each type of fatty acid used.&quot;</p>
<p>Adv
Exp Med Biol 266:3-15, 1989, <strong>&quot;Lipofuscin and ceroid formation:
the cellular recycling system,&quot;</strong> Harman, D.</p>
<p>Mech
Ageing Dev 2001 Apr 15;122(4):427-43. <strong>Effect of the degree
of fatty acid unsaturation of rat heart mitochondria on their rates
of H2O2 production and lipid and protein oxidative damage.</strong> Herrero
A, Portero-Otin M, Bellmunt MJ, Pamplona R, Barja G. &quot;Previous
comparative studies have shown that long-lived animals have lower fatty
acid double bond content in their mitochondrial membranes than short-lived
ones. In order to ascertain whether this trait protects mitochondria
by decreasing lipid and protein oxidation and oxygen radical generation,
the double bond content of rat heart mitochondrial membranes was manipulated
by chronic feeding with semi-purified AIN-93G diets rich in highly unsaturated
(UNSAT) or saturated (SAT) oils. UNSAT rat heart mitochondria had significantly
higher double bond content and lipid peroxidation than SAT mitochondria.
They also showed increased levels of the markers of protein oxidative
damage malondialdehyde-lysine, protein carbonyls, and N(e)-(carboxymethyl)lysine
adducts.&quot; &quot;These results demonstrate that increasing the degree
of fatty acid unsaturation of heart mitochondria increases oxidative
damage to their lipids and proteins, and can also increase their rates
of mitochondrial oxygen radical generation in situations in which the
degree of reduction of Complex III is higher than normal. These observations
strengthen the notion that the relatively low double bond content of
the membranes of long-lived animals could have evolved to protect them
from oxidative damage.&quot;</p>
<p>Biochem
J. 1994 May 15;300 ( Pt 1):251-5. <strong>Regulation of fibrinolysis by non-esterified
fatty acids.</strong> Higazi AA, Aziza R, Samara AA, Mayer M. &quot;Examination
of the fatty acid specificity showed that a minimal chain length of
16 carbon atoms and the presence of at least one double bond, preferably
in a cis configuration, were required for inhibition of the fibrinolytic
activity of plasmin.&quot;</p>
<p>B.
A. Houssay and C. Martinez, <strong>&quot;Experimental diabetes and diet,&quot;</strong>
Science 105, 548-549, 1947. </p>
<p>J
Theor Biol. 2005 May 21;234(2):277-88. <strong>On the importance of fatty
acid composition of membranes for aging.</strong> Hulbert AJ.</p>
<p>Mech
Ageing Dev. 2006 Apr 16; <strong>Extended longevity of wild-derived mice
is associated with peroxidation-resistant membranes. </strong>
Hulbert AJ, Faulks SC, Harper JM, Miller RA, Buffenstein R. &quot;Muscle
and liver phospholipids from these long-living mice lines have a reduced
amount of the highly polyunsaturated omega-3 docosahexaenoic acid compared
to the DC mice, and consequently their membranes are less likely to
peroxidative damage. The relationship between maximum longevity and
membrane peroxidation index is similar for these mice lines as previously
observed for mammals in general. It is suggested that peroxidation-resistant
membranes may be an important component of extended longevity.&quot;</p>
<p>Virchows
Arch B Cell Pathol. 1975 Nov 21;19(3):239-54.<strong> [Ultrastructure and
morphogenesis of ceroid pigment. II. Late changes of lysosomes in Kupffer
cells of rat liver after phagocytosis of unsaturated lipids] </strong>
Kajihara H, Totovic V, Gedigk P. &quot;These lipids, which have been
changed in their molecular structure, cannot be hydrolized by lysosomal
enzymes. They remain as an indigestible material, as a waste product
in lysosomal residual bodies. Both lipofuscin and ceroid are lysosomal
structures containing oxidized and polymerized lipids.&quot; </p>
<p>Reprod
Nutr Dev. 1998 Jan-Feb;38(1):31-7. <strong>Effect of a high linoleic acid
diet on delta 9-desaturase activity, lipogenesis and lipid composition
of pig subcutaneous adipose tissue.</strong> Kouba M, Mourot J. </p>
<p>Gerontology
1993;39(1):7-18.<strong> Modulation of membrane phospholipid fatty acid composition
by age and food restriction.</strong> Laganiere S, Yu BP. H.M. &quot;Phospholipids
from liver mitochondrial and microsomal membrane preparations were analyzed
to further assess the effects of age and lifelong calorie restriction
on membrane lipid composition.&quot; &quot;The data revealed characteristic
patterns of age-related changes in ad libitum (AL) fed rats: membrane
levels of long-chain polyunsaturated fatty acids, 22:4 and 22:5, increased
progressively, while membrane linoleic acid (18:2) decreased steadily
with age. Levels of 18:2 fell by approximately 40%, and 22:5 content
almost doubled making the peroxidizability index increase with age.&quot;
&quot;We concluded that the membrane-stabilizing action of long-term
calorie restriction relates to the selective modification of membrane
long-chain polyunsaturated fatty acids during aging.&quot;</p>
<p>Free
Radic Biol Med 1999 Feb;26(3-4):260-5. <strong>Modulation of cardiac
mitochondrial membrane fluidity by age and calorie intake.</strong> Lee J,
Yu BP, Herlihy JT. &quot;The fatty acid composition of the mitochondrial
membranes of the two ad lib fed groups differed: the long-chain polyunsaturated
22:4 fatty acid was higher in the older group, although linoleic acid
(18:2) was lower. DR eliminated the differences.&quot; &quot;Considered
together, these results suggest that DR maintains the integrity of the
cardiac mitochondrial membrane fluidity by minimizing membrane damage
through modulation of membrane fatty acid profile.&quot;</p>
<p>Lipids
2001 Jun;36(6):589-93. <strong>Effect of dietary restriction on age-related
increase of liver susceptibility to peroxidation in rats.</strong> Leon TI,
Lim BO, Yu BP, Lim Y, Jeon EJ, Park DK.</p>
<p>Lipids
22(3), 133-6, 1987. <strong>Effects of parenteral nutrition with high doses
of linoleate on the developing human liver and brain,</strong> Martinez,
M., and A. Ballabriga.</p>
<p>J
Pharmacol Exp Ther. 1995 Jan;272(1):469-75. <strong>Acetic acid-induced colitis
in normal and essential fatty acid deficient rats.</strong> Mascolo N, Izzo
AA, Autore G, Maiello FM, Di Carlo G, Capasso F.</p>
<p>Biochem
Pharmacol. 1990 Mar 1;39(5):879-89. <strong>Histamine release from rat mast
cells induced by metabolic activation of polyunsaturated fatty acids
into free radicals.</strong> Masini E, Palmerani B, Gambassi F, Pistelli
A, Giannella E, Occupati B, Ciuffi M, Sacchi TB, Mannaioni PF.</p>
<p>J
Nutrit 10:63(1935). <strong>The effect of retarded growth upon length of
the life span and upon the ultimate body size.</strong> McCay, CM., Crowell,
MF., and Maynard, LA.</p>
<p>McCollum
EV. 1957. <strong>A History of Nutrition.</strong> Boston: Houghton Mifflin. p
374.</p>
<p>J
Biol Chem. 2003 Oct 24;278(43):42012-9. <strong>Pyridoxamine traps intermediates
in lipid peroxidation reactions in vivo: evidence on the role of lipids
in chemical modification of protein and development of diabetic complications.</strong>
Metz TO, Alderson NL, Chachich ME, Thorpe SR, Baynes JW.</p>
<p>FEBS
Lett. 1998 Oct 16;437(1-2):24-8. <strong>Generation of protein carbonyls
by glycoxidation and lipoxidation reactions with autoxidation products
of ascorbic acid and polyunsaturated fatty acids. </strong>
Miyata T, Inagi R, Asahi K, Yamada Y, Horie K, Sakai H, Uchida K, Kurokawa
K.</p>
<p>Naunyn
Schmiedebergs Arch Pharmacol. 1996 Jul;354(2):109-19. <strong>Exposure to
the n-3 polyunsaturated fatty acid docosahexaenoic acid impairs alpha
1-adrenoceptor-mediated contractile responses and inositol phosphate
formation in rat cardiomyocytes.</strong> Reithmann C, Scheininger C, Bulgan
T, Werdan K. “The results presented show that <strong>chronic n-3 polyunsaturated
fatty acid pretreatment of rat cardiomyocytes leads to a marked impairment
of alpha 1-adrenoceptor-induced positive inotropic effects and induction
of arrhythmias concomitant with a n-3 fatty acid-induced decrease in
IP3 formation.” </strong></p>
<p>Nutrition.
2000 Jan;16(1):11-4<strong>. Effects of eicosapentaenoic acid intake on plasma
fibrinolytic and coagulation activity by using physical load in the
young.</strong> Sakamoto N, Nishiike T, Iguchi H, Sakamoto K. “<strong>Thus,
as determined by the load, a small amount of daily EPA intake clearly
decreased fibrinolytic activity and increased coagulation activity.”</strong> </p>
<p>Diabetes.
2005 Aug;54(8):2314-9. <strong>Insulin resistance and type 2 diabetes in
high-fat-fed mice are linked to high glycotoxin intake.</strong> Sandu O,
Song K, Cai W, Zheng F, Uribarri J, Vlassara H. “These results demonstrate
that the development of insulin resistance and type 2 diabetes during
prolonged high-fat feeding are linked to the excess AGEs/advanced lipoxidation
end products inherent in fatty diets.”</p>
<p>Nutr
Cancer 1998;30(2):137-43. <strong>Effects of dietary n-3-to-n-6 polyunsaturated
fatty acid ratio on mammary carcinogenesis in rats.</strong> Sasaki T, Kobayashi
Y, Shimizu J, Wada M, In&#39;nami S, Kanke Y, Takita T. &quot;Dietary fat
was fed to the rats as 10% of the total feed weight, starting two weeks
before the initiation. An increase in the n-3/n-6 ratio did not suppress
the incidence or reduce the latency of mammary tumor development. The
number and weight of mammary tumors per tumor-bearing rat tended to
be large in the group with an n-3/n-6 ratio of 7.84 compared with those
in the other groups. <strong>As the n-3/n-6 ratios were elevated, the total
number and weight of tumors increased gradually.&quot;</strong> &quot;These
results suggested that the increase in the n-3/n-6 ratio of dietary
fat with the fixed PUFA-to-saturated fatty acid ratio cannot suppress
the mammary carcinogenesis but can promote development of tumors, despite
reduced PGE2 concentration in the tumor.&quot;</p>
<p>J
Cardiovasc Pharmacol. 2006 Mar;47(3):493-9. <strong>Mildronate, a novel fatty
acid oxidation inhibitor and antianginal agent, reduces myocardial infarct
size without affecting hemodynamics.</strong> Sesti C, Simkhovich BZ, Kalvinsh
I, Kloner RA. &quot;Mildronate is a fatty acid oxidation inhibitor approved
as an antianginal drug in parts of Europe.&quot;</p>
<p>J
Nutr 2000 Dec;130(12):3028-33. <strong>Polyunsaturated (n-3) fatty
acids susceptible to peroxidation are increased in plasma and tissue
lipids of rats fed docosahexaenoic acid-containing oils.</strong> Song JH,
Fujimoto K, Miyazawa T.. &quot;Thus, high incorporation of (n-3) fatty
acids (mainly DHA) into plasma and tissue lipids due to DHA-containing
oil ingestion may undesirably affect tissues by enhancing susceptibility
of membranes to lipid peroxidation and by disrupting the antioxidant
system.&quot;</p>
<p>Diabetes
Nutr Metab. 2002 Aug;15(4):205-14. <strong>Long-term effect of fish oil diet
on basal and stimulated plasma glucose and insulin levels in ob/ob mice.</strong>
Steerenberg PA, Beekhof PK, Feskens EJ, Lips CJ, Hoppener JW, Beems
RB. “We have investigated, in comparison to low and high fat diets,
the effect of a fish oil diet on basal and stimulated plasma glucose
and insulin levels in male and female ob/ob mice.” “Intercurrent
deaths were found especially in the fish oil diet group. Compared to
the other diet groups, plasma insulin levels of the fish oil diet group
were significantly increased 3 months after the start of the diet and
remained higher for another 3 months.” “At 12 months, microscopy
revealed an increased severity of hepatic brown pigment accumulation
and extramedullary haematopoiesis in the spleen of mice fed with fish
oil.” “Fish oil diet also increased intercurrent mortality. However,
a consistent course of death could not be established using morphological
parameters.”</p>
<p>J
Biol Chem. 2002 Feb 15;277(7):5692-7. <strong>Unsaturated fatty acids inhibit
cholesterol efflux from macrophages by increasing degradation of ATP-binding
cassette transporter A1.</strong> Wang Y, Oram JF. “These findings raise
the possibility that an increased supply of unsaturated fatty acids
in the artery wall promotes atherogenesis by impairing the ABCA1 cholesterol
secretory pathway in macrophages.”</p>
<p>J
Biol Chem. 2005 Oct 28;280(43):35896-903. Epub 2005 Aug 23. <strong>Unsaturated
fatty acids phosphorylate and destabilize ABCA1 through a phospholipase
D2 pathway.</strong> Wang Y, Oram JF. &quot;ATP-binding cassette transporter
ABCA1 mediates the transport of cholesterol and phospholipids from cells
to HDL apolipoproteins and thus modulates HDL levels and atherogenesis.
Unsaturated fatty acids, which are elevated in diabetes, impair the
ABCA1 pathway in cultured cells by destabilizing ABCA1 protein.&quot;
&quot;Unsaturated but not saturated fatty acids stimulated phospholipase
D (PLD) activity, the PLD inhibitor 1-butanol prevented the unsaturated
fatty acid-induced reduction in ABCA1 levels, and the PLD2 activator
mastoparan markedly reduced ABCA1 protein levels, implicating a role
for PLD2 in the ABCA1 destabilizing effects of fatty acids.&quot; &quot;These
data provide evidence that intracellular unsaturated acyl-CoA derivatives
destabilize ABCA1 by activating a PLD2 signaling pathway.&quot;</p>
<p>Isr
J Med Sci. 1996 Nov;32(11):1134-43. <strong>Diet and disease--the Israeli
paradox: possible dangers of a high omega-6 polyunsaturated fatty acid
diet.</strong> Yam D, Eliraz A, Berry EM. “Thus, rather than being beneficial,
high omega-6 PUFA diets may have some long-term side effects, within
the cluster of hyperinsulinemia, atherosclerosis and tumorigenesis.”
</p>
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