The Importance of the Omega-6/Omega-3
Fatty Acid Ratio in Cardiovascular Disease
and Other Chronic Diseases
ARTEMIS P. SIMOPOULOS
The Center for Genetics, Nutrition and Health, Washington, DC 20009
Several sources of information suggest that human beings
evolved on a diet with a ratio of omega-6 to omega-3 essential
fatty acids (EFA) of
1 whereas in Western diets the ratio is 15/1–
16.7/1. Western diets are deficient in omega-3 fatty acids, and
have excessive amounts of omega-6 fatty acids compared with
the diet on which human beings evolved and their genetic
patterns were established. Excessive amounts of omega-6
polyunsaturated fatty acids (PUFA) and a very high omega-6/
omega-3 ratio, as is found in today’s Western diets, promote the
pathogenesis of many diseases, including cardiovascular dis-
ease, cancer, and inflammatory and autoimmune diseases,
whereas increased levels of omega-3 PUFA (a lower omega-6/
omega-3 ratio), exert suppressive effects. In the secondary
prevention of cardiovascular disease, a ratio of 4/1 was
associated with a 70% decrease in total mortality. A ratio of
2.5/1 reduced rectal cell proliferation in patients with colorectal
cancer, whereas a ratio of 4/1 with the same amount of omega-3
PUFA had no effect. The lower omega-6/omega-3 ratio in women
with breast cancer was associated with decreased risk. A ratio of
2–3/1 suppressed inflammation in patients with rheumatoid
arthritis, and a ratio of 5/1 had a beneficial effect on patients
with asthma, whereas a ratio of 10/1 had adverse consequences.
These studies indicate that the optimal ratio may vary with the
disease under consideration. This is consistent with the fact that
chronic diseases are multigenic and multifactorial. Therefore, it
is quite possible that the therapeutic dose of omega-3 fatty acids
will depend on the degree of severity of disease resulting from
the genetic predisposition. A lower ratio of omega-6/omega-3
fatty acids is more desirable in reducing the risk of many of the
chronic diseases of high prevalence in Western societies, as well
as in the developing countries. Exp Biol Med 233:674–688, 2008
Key words: balanced omega-6/omega-3 ratio; dietary omega-3 fatty
acids; inﬂammation; cardiovascular disease; chronic diseases; diet-
The interaction of genetics and environment, nature,
and nurture is the foundation for all health and disease. In
the last two decades, using the techniques of molecular
biology, it has been shown that genetic factors determine
susceptibility to disease and environmental factors deter-
mine which genetically susceptible individuals will be
affected (1–6). Nutrition is an environmental factor of major
importance. Using the tools of molecular biology and
genetics, research is deﬁning the mechanisms by which
genes inﬂuence nutrient absorption, metabolism and ex-
cretion, taste perception, and degree of satiation; and the
mechanisms by which nutrients inﬂuence gene expression.
Whereas major changes have taken place in our diet over the
past 10,000 years since the beginning of the Agricultural
Revolution, our genes have not changed. The spontaneous
mutation rate for nuclear DNA is estimated at 0.5% per
million years. Therefore, over the past 10,000 years there
has been time for very little change in our genes, perhaps
0.005%. In fact, our genes today are very similar to the
genes of our ancestors during the Paleolithic period 40,000
years ago, at which time our genetic proﬁle was established
(7). Humans today live in a nutritional environment that
differs from that for which our genetic constitution was
selected. Studies on the evolutionary aspects of diet indicate
that major changes have taken place in our diet, particularly
in the type and amount of essential fatty acids and in the
antioxidant content of foods (7–11) (Fig. 1).
Today industrialized societies are characterized by 1) an
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and Health, 2001 S Street, NW, Suite 530, Washington, DC 20009. E-mail:
Copyright Ó 2008 by the Society for Experimental Biology and Medicine
increase in energy intake and decrease in energy expendi-
ture; 2) an increase in saturated fat, omega-6 fatty acids and
trans fatty acids, and a decrease in omega-3 fatty acid
intake; 3) a decrease in complex carbohydrates and ﬁber; 4)
an increase in cereal grains and a decrease in fruits and
vegetables; and 5) a decrease in protein, antioxidants and
calcium intake (7, 9, 12–15) (Tables 1 and 2). The increase
in trans fatty acids is detrimental to health as shown in
Table 3 (17). In addition, trans fatty acids interfere with the
desaturation and elongation of both omega-6 and omega-3
fatty acids, thus further decreasing the amount of arach-
idonic acid, eicosapentaenoic acid and docosahexaenoic
acid availability for human metabolism (18).
The beneﬁcial health effects of omega-3 fatty acids,
eicosapentaenoic acid (EPA) and docosahexaenoic acid
(DHA) were described ﬁrst in the Greenland Eskimos who
consumed a high seafood diet and had low rates of coronary
heart disease, asthma, type 1 diabetes mellitus, and multiple
sclerosis. Since that observation, the beneﬁcial health effects
of omega-3 fatty acids have been extended to include
beneﬁts related to cancer, inﬂammatory bowel disease,
rheumatoid arthritis, and psoriasis (19).
Whereas evolutionary maladaptation leads to reproduc-
tive restriction (or differential fertility), the rapid changes in
our diet, particularly the last 150 years, are potent promoters
of chronic diseases such as atherosclerosis, essential hyper-
tension, obesity, diabetes, arthritis and other autoimmune
diseases, and many cancers, especially cancer of the breast
(20), colon (21), and prostate (22). In addition to diet,
sedentary lifestyles and exposure to noxious substances
interact with genetically controlled biochemical processes
leading to chronic disease.
In this review, I discuss the importance of the balance
of omega-6 and omega-3 essential fatty acids in the
prevention and treatment of coronary artery disease, hyper-
tension, diabetes, arthritis, osteoporosis, other inﬂammatory
and autoimmune disorders, cancer and mental health, and
the mechanisms involved.
Figure 1. Hypothetical scheme of fat, fatty acid (x6, x3, trans and total) intake (as percent of calories from fat) and intake of vitamins E and C
(mg/d). Data were extrapolated from cross-sectional analyses of contemporary hunter-gatherer populations and from longitudinal observations
and their putative changes during the preceding 100 years (9).
Table 1. Estimated Omega-3 and Omega-6 Fatty
Acid Intake in the Late Paleolithic Period (g/d)
AA (x6) 1.81
EPA (x3) 0.39
DTA (x6) 0.12
DPA (x3) 0.42
DHA (x3) 0.27
Ratios of x6/x3
Total x6/x3 0.79
Data from Eaton et al. (13).
Assuming an energy intake of 35:65 of animal:plant sources.
LA, linoleic acid; ALA, linolenic acid; AA, arachidonic acid; EPA,
eicosapentaenoic acid; DTA, docosatetranoic acid; DPA, docosa-
pentaenoic acid; DHA, docosahexaenoic acid.
OMEGA-6/OMEGA-3 FATTY ACID RATIO 675
Imbalance of Omega-6/Omega-3
Food technology and agribusiness provided the eco-
nomic stimulus that dominated the changes in the food
supply (23, 24). From per capita quantities of foods
available for consumption in the U.S. national food supply
in 1985, the amount of EPA is reported to be about 50 mg
per capita/day and the amount of DHA is 80 mg per capita/
day. The two main sources are ﬁsh and poultry (25). It has
been estimated that the present Western diet is ‘‘deﬁcient’’ in
omega-3 fatty acids with a ratio of omega-6 to omega-3 of
15–20/1, instead of 1/1 as is the case with wild animals and
presumably human beings (7–11, 13, 26–28) (Table 4).
Before the 1940s cod-liver oil was ingested mainly by
children as a source of vitamin A and vitamin D with the
usual dose being a teaspoon. Once these vitamins were
synthesized, consumption of cod-liver oil was drastically
decreased, contributing further to the decrease of EPA and
DHA intake. Table 5 shows ethnic differences in fatty acid
concentrations in thrombocyte phospholipids, the ratios of
omega-6/omega-3 fatty acids, and percentage of all deaths
from cardiovascular disease (16).
An absolute and relative change of omega-6/omega-3 in
the food supply of Western societies has occurred over the
last 150 years. A balance existed between omega-6 and
omega-3 for millions of years during the long evolutionary
history of the genus Homo, and genetic changes occurred
partly in response to these dietary inﬂuences. During
evolution, omega-3 fatty acids were found in all foods
consumed: meat, wild plants, eggs, ﬁsh, nuts and berries
(29–38). Studies by Cordain et al. (39) on wild animals
conﬁrm the original observations of Crawford and Sinclair
et al. (27,40). However, rapid dietary changes over short
periods of time as have occurred over the past 100–150 yr is
a totally new phenomenon in human evolution (13, 15, 41–
43) (Table 6).
Biological Effects and the Omega-6/Omega-3 Ratio
There are two classes of essential fatty acids (EFA),
omega-6 and omega-3. The distinction between omega-6
and omega-3 fatty acids is based on the location of the ﬁrst
double bond, counting from the methyl end of the fatty acid
molecule. In the omega-6 fatty acids, the ﬁrst double bond is
between the 6th and 7th carbon atoms and for the omega-3
fatty acids the ﬁrst double bond is between the 3rd and 4th
Table 2. Late Paleolithic and Currently Recommended Nutrient Composition for Americans
FNB-IOM 1989 recommendations
FNB-IOM 2005 recommendations
Total dietary energy, (%)
Protein 33 12 10–35
Carbohydrate 46 58 45–65
Fat 21 30 20–35
Alcohol ;0– –
1.41 1.00 –
Cholesterol (mg) 520 300 ,300
Fiber (g) 100–150 30–60 38
Sodium (mg) 690 1100–3300 ,2300
Calcium (mg) 1500–2000 800–1600 1000–1300
Ascorbic acid (mg) 440 60 75
Modified from Eaton et al. (13).
Data from DRI Tables on the internet: http://www.iom.edu/CMS/3788/4574.aspx
P/S, polyunsaturated to saturated fat.
Table 3. Adverse Effects of Trans Fatty Acids
Decrease or inhibit
Decrease or inhibit incorporation of other fatty acids into
Decrease high-density lipoprotein (HDL)
Inhibit delta-6 desaturase (interfere with elongation and
desaturation of essential fatty acids)
Decrease serum testosterone (in male rats)
Cross the placenta and decrease birth weight (in humans)
Low-density lipoprotein (LDL)
Lipoprotein (a) [Lp(a)]
Cholesterol transfer protein (CTP)
Abnormal morphology of sperm (in male rats)
Modified from reference 17.
Table 4. Ratios of Dietary Omega-6:Omega-3 Fatty
Acids in the Late Paleolithic Period and in Current
Western Diets (United States) (g/d)
LA:ALA 0.70 18.75
AAþDTA:EPAþDPAþDHA 1.79 3.33
Total 0.79 16.74
LA, linoleic acid; ALA, linolenic acid; AA, arachidonic acid; EPA,
eicosapentaenoic acid; DTA, docosatetranoic acid; DPA, docosa-
pentaenoic aci d; DHA, doc osahexa enoi c acid. Rep rin ted with
permission from reference (15).
carbon atoms. Monounsaturates are represented by oleic
acid, an omega-9 fatty acid, which can be synthesized by all
mammals including humans. Its double bond is between the
9th and 10th carbon atoms.
Omega-6 and omega-3 fatty acids are essential because
humans, like all mammals, cannot make them and must
obtain them in their diet. Omega-6 fatty acids are
represented by linoleic acid (LA; 18:2x6) and omega-3
fatty acids by a-linolenic acid (ALA; 18:3x3). LA is
plentiful in nature and is found in the seeds of most plants
except for coconut, cocoa, and palm. ALA on the other hand
is found in the chloroplasts of green leafy vegetables, and in
the seeds of ﬂax, rape, chia, perilla and in walnuts. Both
EFA are metabolized to longer-chain fatty acids of 20 and
22 carbon atoms. LA is metabolized to arachidonic acid
(AA; 20:4x6), and LNA to EPA (20:5x3) and DHA
(22:6x3), increasing the chain length and degree of
unsaturation by adding extra double bonds to the carboxyl
end of the fatty acid molecule (Fig. 2).
Humans and other mammals, except for carnivores such
as lions, can convert LA to AA and ALA to EPA and DHA,
but it is slow (44). This conversion was shown by using
deuterated ALA (45). There is competition between omega-
6 and omega-3 fatty acids for the desaturation enzymes.
However, both D-4 and D-6 desaturases prefer omega-3 to
omega-6 fatty acids (44, 46, 47). But, a high LA intake
interferes with the desaturation and elongation of ALA (45,
48). Trans fatty acids interfere with the desaturation and
elongation of both LA and ALA. D-6 desaturase is the
limiting enzyme and there is some evidence that it decreases
with age (44). Premature infants (49), hypertensive individ-
uals (50), and some diabetics (51) are limited in their ability
to make EPA and DHA from ALA. These ﬁndings are
important and need to be considered when making dietary
recommendations. EPA and DHA are found in the oils of
ﬁsh, particularly fatty ﬁsh. AA is found predominantly in the
phospholipids of grain-fed animals and eggs.
LA, ALA, and their long-chain derivatives are important
components of animal and plant cell membranes. In
mammals and birds, the n-3 fatty acids are distributed
selectively among lipid classes. ALA is found in triglycer-
ides, in cholesteryl esters, and in very small amounts in
phospholipids. EPA is found in cholesteryl esters, triglycer-
ides, and phospholipids. DHA is found mostly in phospho-
lipids. In mammals, including humans, the cerebral cortex,
retina, and testis and sperm are particularly rich in DHA.
DHA is one of the most abundant components of the brain’s
structural lipids. DHA, like EPA, can be derived only from
direct ingestion or by synthesis from dietary EPA or ALA.
Mammalian cells cannot convert omega-6 to omega-3
fatty acids because they lack the converting enzyme, omega-
3 desaturase. LA, the parent omega-6 fatty acid, and ALA,
the parent omega-3 fatty acid, and their long-chain
derivatives are important components of animal and plant
cell membranes (Fig. 2). These two classes of EFA are not
interconvertible, are metabolically and functionally distinct,
and often have important opposing physiological functions.
When humans ingest ﬁsh or ﬁsh oil, the EPA and DHA
from the diet partially replace the omega-6 fatty acids,
especially AA, in the membranes of probably all cells, but
especially in the membranes of platelets, erythrocytes,
neutrophils, monocytes, and liver cells (reviewed in
references 8, 52). Whereas cellular proteins are genetically
determined, the polyunsaturated fatty acid (PUFA) compo-
sition of cell membranes is to a great extent dependent on
the dietary intake. AA and EPA are the parent compounds
for eicosanoid production (8) (Tables 7–8, Fig. 3).
Because of the increased amounts of omega-6 fatty
acids in the Western diet, the eicosanoid metabolic products
from AA, speciﬁcally prostaglandins, thromboxanes, leuko-
trienes, hydroxy fatty acids, and lipoxins, are formed in
larger quantities than those formed from omega-3 fatty
acids, speciﬁcally EPA (8). The eicosanoids from AA are
biologically active in very small quantities and, if they are
formed in large amounts, they contribute to the formation of
thrombus and atheromas; to allergic and inﬂammatory
disorders, particularly in susceptible people; and to
proliferation of cells. Thus, a diet rich in omega-6 fatty
acids shifts the physiological state to one that is prothrom-
botic and proaggregatory, with increases in blood viscosity,
vasospasm, and vasocontriction and decreases in bleeding
time. Bleeding time is decreased in groups of patients with
hypercholesterolemia, hyperlipoproteinemia, myocardial in-
Table 5. Ethnic Differences in Fatty Acid Concen-
trations in Thrombocyte Phospholipids and Percentage
of All Deaths from Cardiovascular Disease
Arachidonic acid (20:4x6) 26 21 8.3
(20:5x3) 0.5 1.6 8.0
Ratio of x6/x350121
cardiovascular disease 45 12 7
Data modified from reference 16.
Table 6. Omega-6:Omega-3 Ratios in Various
Population x6/x3 Reference
Paleolithic 0.79 (13)
Greece prior to 1960 1.00–2.00 (15)
Current Japan 4.00 (41)
Current India, rural 5–6.1 (42)
Current United Kingdom and
Current United States 16.74 (13)
Current India, urban 38–50 (42)
OMEGA-6/OMEGA-3 FATTY ACID RATIO 677
farction, other forms of atherosclerotic disease, and diabetes
(obesity and hypertriglyceridemia). Bleeding time is longer
in women than in men and longer in young than in old
people. There are ethnic differences in bleeding time that
appear to be related to diet.
Linoleic Acid Increases Low-Density Lipopro-
tein Oxidation and Severity of Coronary Athero-
sclerosis. Oxidative modiﬁcation increases the
atherogenicity of low-density lipoprotein (LDL) cholesterol.
Oxidized LDL is taken up by scavenger receptors that do
not recognize unmodiﬁed LDL leading to foam cell
formation. Diets enriched with LA increase the LA content
of LDL and its susceptibility to oxidation (53, 54). Reaven
et al. (55) showed that a LA-enriched diet especially affects
oxidation of small, dense LDL. Louheranta et al. (56)
showed that as the percent of energy intake from LA
increased from the lower quartile 2.9% to the highest 6.4%
so did the LDL oxidation. In their study, the average energy
from LA was 4.6%. In another small cross-sectional study,
enhanced susceptibility of LDL to oxidize was associated
with severity of coronary atherosclerosis (57).
Linoleic Acid Inhibits Eicosapentaenoic Acid
Incorporation from Dietary Fi sh Oil Supplements in
Human Subjects. Cleland et al. showed that LA inhibits
EPA incorporation from dietary ﬁsh oil supplements in
human subjects (58). Thirty healthy male subjects were
randomly allocated into one of two treatment groups. One
group was on a high LA and low saturated fatty acid diet,
whereas the other group was on a low LA and low saturated
fat diet. The difference in the low LA and low saturated fatty
acid diet was made up with monounsaturated fatty acids
(olive oil). After a 3-week run-in period, the subjects
consumed a ﬁsh oil supplement containing 1.6 g EPA and
0.32 g DHA per day. After four weeks of ﬁsh oil
Figure 2. Elongation and desaturation of omega-6 and omega-3 polyunsaturated fatty acids.
supplementation, the incorporation of EPA in neutrophil
membrane phospholipids was highest in the lowest LA
group, indicating that the ingestion of omega-6 fatty acids
within the diet is an important determinant of EPA
incorporation into neutrophil membranes. This study also
shows that monounsaturated fatty acids, in this case olive
oil, do not interfere with EPA incorporation.
Decreasing Linoleic Acid with Constant a-
Linolenic Acid in Dietary Fats Increases (Omega-
3) Eicosapentaenoic Acid in Plasma Phospholipids
in Healthy Men. Liou et al. carried out a study in which
decreasing levels of LA with constant ALA led to increases
of EPA in plasma phospholipids in healthy men (59). The
omega-6/omega-3 dietary ratio varied between 10/1 to 4/0
of LA/ALA. It is unfortunate that the authors did not have a
lower ratio of 2–1/1 omega-6/omega-3, which is closer to
the ratio on which humans evolved. At a ratio of 1/1,
Zampelas et al. showed a decrease in C-reactive protein
(CRP), which Liou et al. at a ratio of 4/1 did not show (60).
A Lower Omega-6/Omega-3 Ratio as Part of a
Mediterranean Diet Decreases Vascular Endothe-
lial Growth Factor. Ambring et al. studied the ratio of
serum phospholipid omega-6 to omega-3 fatty acids, the
number of leukocytes and platelets, and vascular endothelial
growth factor (VEGF) in healthy subjects on an ordinary
Swedish diet and on a Mediterranean-inspired diet that was
high in ﬁsh and ﬂaxseed oil (61). This is a very interesting
and important study, because it clearly showed that the serum
phospholipid ratio of omega-6/omega-3 fatty acids was
substantially lowered after the Mediterranean diet versus the
Swedish diet. The omega-6/omega-3 ratio was 4.72 6 0.19
on the Swedish diet and 2.60 6 0.19 on the Mediterranean
diet (P , 0.0001). There was no change in CRP or
interleukin-6 (IL-6), but the total number of leukocytes was
10% lower after the Mediterranean diet, the total number of
platelets was 15% lower, and so was the serum VEGF, 206
6 25 pg/mL versus 237 6 30 on the Swedish diet (P ¼
0.0014). The authors concluded that ‘‘A Mediterranean-
inspired diet reduces the number of platelets and leukocytes
and VEGF concentrations in healthy subjects. This may be
linked to higher serum concentrations of omega-3 fatty acids,
which promote a favorable composition of phospholipids.’’
These ﬁndings are consistent with our studies on the
traditional diet of Greece prior to 1960 that was rich in
ALA, EPA and DHA and balanced in the omega-6/omega-3
ratio, which distinguished it from other Mediterranean diets
(62, 63), by being similar in the omega-6/omega-3 ratio to
the diet on which human beings evolved (7–13, 26–28).
As the Omega-6/Omega-3 Ratio Decreases, So
Does the Platelet Aggregation. Freese et al. compared
the effects of two diets rich in monounsaturated fatty acids,
differing in their LA/ALA ratio on platelet aggregation in
human volunteers (64). Both diets were similar in saturated,
monounsaturated and polyunsaturated fatty acids. The
results showed that platelet aggregation in vitro decreases
as the ratio of LA/ALA decreases in diets rich in
monounsaturated fatty acids.
The higher the ratio of omega-6/omega-3 fatty acids in
platelet phospholipids, the higher the death rate from
cardiovascular disease (16). Excessive amounts of omega-
6 PUFA and a very high omega-6/omega-3 ratio, as is found
in today’s Western diets, promote the pathogenesis of many
diseases, including cardiovascular disease, cancer, and
inﬂammatory and autoimmune diseases, whereas increased
levels of omega-3 PUFA (a lower omega-6/omega-3 ratio),
exert suppressive effects (65).
Plasma Omega-6/Omega-3 Ratio and Inflamma-
tory Markers. Ferrucci et al. studied the relationship of
plasma PUFA to circulating inﬂammatory markers in 1123
persons aged 20–98 years in a community-based sample
(66). The total omega-3 fatty acids were independently
associated with lower levels of pro-inﬂammatory markers
[IL-6, IL-1ra, tumor necrosis factor-a (TNFa), CRP], and
higher anti-inﬂammatory markers [soluble IL-6r, IL-10,
transforming growth factor-a (TGFa)] independent of
confounders. The omega-6/omega-3 ratio was a strong
negative correlate of IL-10. The authors concluded,
‘‘Omega-3 fatty acids are beneﬁcial in patients affected by
diseases characterized by active inﬂammation.’’
The Balance of Omega-6/Omega-3 Fatty Acids Is
Important for Health: The Evidence from Gene
Further support for the need to balance the omega-6/
omega-3 EFA comes from the studies of Kang et al. (67,
68), which clearly show the ability of both normal rat
cardiomyocytes and human breast cancer cells in culture to
form all the omega-3’s from omega-6 fatty acids when fed
the cDNA encoding omega-3 fatty acid desaturase obtained
from the roundworm Caenorhabditis elegans (C. elegans).
The omega-3 desaturase efﬁciently and quickly converted
the omega-6 fatty acids that were fed to the cardiomyocytes
in culture to the corresponding omega-3 fatty acids. Thus,
Table 7. Effects of Ingestion of EPA and DHA from
Fish or Fish Oil
Decreased production of prostaglandin E
A decrease in thromboxane A
, a potent platelet aggregator
A decrease in leukotriene B
formation, an inducer of
inflammation, and a powerful inducer of leukocyte
chemotaxis and adherence
An increase in thromboxane A
, a weak platelet aggregator
and weak vasoconstrictor
An increase in prostacyclin PGI
, leading to an overall
increase in total prostacyclin by increasing PGI
a decrease in PGI
, both PGI
vasodilators and inhibitors of platelet aggregation
An increase in leukotriene B
, a weak inducer of
inflammation and a weak chemotactic agent
OMEGA-6/OMEGA-3 FATTY ACID RATIO 679
omega-6 LA was converted to omega-3 ALA and AA was
converted to EPA, so that at equilibrium, the ratio of omega-
6 to omega-3 PUFA was close to 1/1. Further studies
demonstrated that the cancer cells expressing the omega-3
desaturase underwent apoptotic death whereas the control
cancer cells with a high omega-6/omega-3 ratio continued to
proliferate (69). More recently, Kang, et al. showed that
transgenic mice and pigs expressing the C. elegans fat-1
gene encoding an omega-3 fatty acid desaturase are capable
of producing omega-3 from omega-6 fatty acids, leading to
enrichment of omega-3 fatty acids with reduced levels of
omega-6 fatty acids in almost all organs and tissues,
including muscles and milk, with no need of dietary omega-
3 fatty acid supply (70–72). This discovery provides a
unique tool and new opportunities for omega-3 research,
and raises the potential of production of fat-1 transgenic
livestock as a new and ideal source of omega-3 fatty acids to
meet the human nutritional needs. Furthermore, the trans-
genic mouse model is being used widely by scientists for the
study of chronic diseases and for the study of mechanisms
of the beneﬁcial effects of omega-3 fatty acids (73).
Omega-3 Fatty Acids and Gene Expression
Previous studies have shown that fatty acids released
from membrane phospholipids by cellular phospholipases,
or made available to the cell from the diet or other aspects of
the extracellular environment, are important cell signaling
molecules. They can act as second messengers or substitute
for the classical second messengers of the inositide
phospholipid and the cyclic AMP signal transduction
pathways. They can also act as modulator molecules
mediating responses of the cell to extracellular signals.
Recently it has been shown that fatty acids rapidly and
directly alter the transcription of speciﬁc genes (74). In the
case of genes involved in inﬂammation, such as IL-1b, EPA
and DHA suppress IL-1b mRNA whereas AA does not, and
the same effect appears in studies on growth-related early
response gene expression and growth factor (74). In the case
of vascular cell adhesion molecule (VCAM), AA has a
modest suppressing effect relative to DHA. The latter
situation may explain the protective effect of ﬁsh oil toward
colonic carcinogenesis, since EPA and DHA did not
stimulate protein kinase C. PUFA regulation of gene
expression extends beyond the liver and includes genes
Table 8. Effects of Omega-3 Fatty Acids on Factors Involved in the Pathophysiology of Atherosclerosis and
Factor Function Effect of n-3 fatty acid
Arachidonic acid Eicosanoid precursor; aggregates platelets; stimulates
white blood cells
Platelet aggregation; vasoconstriction; increase of
) Prevent platelet aggregation; vasodilation; increase cAMP "
) Neutrophil chemoattractant; increase of intracellular Ca
Fibrinogen A member of the acute phase response; and a blood
Tissue plasminogen activator Increase endogenous fibrinolysis "
Platelet activating factor (PAF) Activates platelets and white blood cells #
Platelet-derived growth factor
Chemoattractant and mitogen for smooth muscles and
Oxygen free radicals Cellular damage; enhance LDL uptake via scavenger
pathway; stimulate arachidonic acid metabolism
Lipid hydroperoxides Stimulate eicosanoid formation #
Interleukin 1 and tumor
Stimulate neutrophil O
free radical formation; stimulate
lymphocyte proliferation; stimulate PAF; express
intercellular adhesion molecule-1 on endothelial cells;
inhibit plasminogen activator, thus, procoagulants
Interleukin-6 Stimulates the synthesis of all acute phase proteins
involved in the inflammatory response: C-reactive
protein; serum amyloid A; fibrinogen; a
C-reactive protein (CRP) An acute phase reactant and an independent risk factor
for cardiovascular disease
Reduces arterial vasoconstrictor response "
Insulin function Increases sensitivity to insulin
VLDL Related to LDL and HDL level #
HDL Decreases the risk for coronary heart disease "
Lp(a) Lipoprotein(a) is a genetically determined protein that
has atherogenic and thrombogenic properties
Triglycerides and chylomicrons Contribute to postprandial lipemia #
such as adipocyte glucose transporter-4, lymphocyte
stearoyl-CoA desaturase 2 in the brain, peripheral mono-
cytes (IL-1b, and VCAM-1) and platelets [platelet derived
growth factor (PDGF)]. Whereas some of the transcriptional
effects of PUFA appear to be mediated by eicosanoids, the
PUFA suppression of lipogenic and glycolytic genes is
independent of eicosanoid synthesis, and appears to involve
a nuclear mechanism directly modiﬁed by PUFA.
Linoleic Acid and Arachidonic Acid Increase
Atherogenesis: Evidence from Diet-Gene Interac-
tions: Genetic Variation and Omega-6 and Omega-
3 Fatty Acid Intake in the Risk for Cardiovascular
As discussed above, leukotrienes are inﬂammatory
mediators generated from AA by the enzyme 5-lipoxyge-
nase. Since atherosclerosis involves arterial inﬂammation,
Dwyer et al. hypothesized that a polymorphism in the 5-
lipoxygenase gene promoter could relate to atherosclerosis
in humans, and that this effect could interact with the dietary
intake of competing 5-lipoxygenase substrates (75). The
study consisted of 470 healthy middle-aged women and
men from the Los Angeles Atherosclerosis study, randomly
sampled. The investigators determined 5-lipoxygenase (5-
LO) genotypes, carotid-artery intima-media thickness,
markers of inﬂammation, CRP, IL-6, dietary AA, EPA,
DHA, LA, and ALA with the use of six 24-hour recalls of
food intake. The results showed that 5-LO variant genotypes
were found in 6.0% of the cohort. Mean intima-media
thickness adjusted for age, sex, height and racial or ethnic
group was increased by 80 6 19 lm from among the
carriers of two variant alleles as compared with the carrier of
the common (wild-type) allele. In multivariate analysis, the
increase in intima-media thickness among carriers of two
variant alleles (62 lm, P , 0.001) was similar in this cohort
to that associated with diabetes (64 lm, P , 0.01) the
strongest common cardiovascular risk factor. Increased
dietary AA signiﬁcantly enhanced the apparent atherogenic
effect of genotype, whereas increased dietary intake of
omega-3 fatty acids EPA and DHA blunted this effect.
Furthermore, the plasma level of CRP of two variant alleles
was increased by a factor of 2, as compared with that among
carriers of the common allele. Thus, genetic variation of 5-
LO identiﬁes a subpopulation with increased risk for
atherosclerosis. The diet-gene interaction further suggests
that dietary omega-6 fatty acids promote, whereas marine
omega-3 fatty acids EPA and DHA inhibit leukotriene-
Figure 3. Oxidative metabolism of arachidonic acid and eicosapentaenoic acid by the cyclooxygenase and 5-lipoxygenase pathways. 5-
HPETE denotes 5-hydroperoxyeicosatetranoic acid and 5-HPEPE denotes 5-hydroxyeicosapentaenoic acid.
OMEGA-6/OMEGA-3 FATTY ACID RATIO 681
mediated inﬂammation that leads to atherosclerosis in this
The prevalence of variant genotypes did differ across
racial and ethnic groups with higher prevalence among
Asians or Paciﬁc Islanders (19.4%), blacks (24.0%) and
other racial or ethnic groups (18.2%) than among Hispanic
subjects (3.6%) and non-Hispanic whites (3.1%). Increased
intima-media thickness was signiﬁcantly associated with
intake of both AA and LA among carriers of the two variant
alleles, but not among carriers of the common alleles. In
contrast, the intake of marine omega-3 fatty acids was
signiﬁcantly and inversely associated with intima-media
thickness only among carriers of the two variant alleles.
Diet-gene interactions were speciﬁc to these fatty acids and
were not observed for dietary intake of monounsaturated,
saturated fat, or other measured fatty acids. The study
constitutes evidence that genetic variation in an inﬂamma-
tory pathway—in this case the leukotriene pathway—can
trigger atherogenesis in humans. These ﬁndings could lead
to new dietary and targeted molecular approaches for the
prevention and treatment of cardiovascular disease accord-
ing to genotype, particularly in the populations of non-
European descent (6).
Clinical Intervention Studies and the Omega-6/
Omega-3 EFA Balance
The Lyon Heart Study was a dietary intervention study
in which a modiﬁed diet of Crete (the experimental diet)
was compared with the prudent diet or Step I American
Heart Association Diet (the control diet) (76–79). The
experimental diet provided a ratio of LA to ALA of 4/1.
This ratio was achieved by substituting olive oil and canola
(oil) margarine for corn oil. Since olive oil is low in LA
whereas corn oil is high, 8% and 61% respectively, the ALA
incorporation into cell membranes was increased in the low
LA diet. Cleland et al. (58) have shown that olive oil
increases the incorporation of omega-3 fatty acids whereas
the LA from corn oil competes. In the Lyon Heart Study, the
ratio of 4/1 of LA/ALA led to a 70% decrease in total
mortality at the end of two years (76).
The Gruppo Italiano per lo Studio della Sopravvivenza
nell’Infarto miocardico (GISSI) Prevenzione Trial partic-
ipants were on a traditional Italian diet plus 850–882 mg of
omega-3 fatty acids at a ratio of 2/1 EPA to DHA (80). The
supplemented group had a decrease in sudden cardiac death
by 45%. Although there are no dietary data on total intake
for omega-6 and omega-3 fatty acids, the difference in
sudden death is most likely due to the increase of EPA and
DHA and a decrease of AA in cell membrane phospholi-
pids. Prostaglandins derived from AA are proarrhythmic,
whereas the corresponding prostaglandins from EPA are not
(81). In the Diet and Reinfarction Trial (DART), Burr et al.
reported a decrease in sudden death in the group that
received ﬁsh advice or took ﬁsh oil supplements relative to
the group that did not (82). Similar results have been
obtained by Singh et al. (83, 84). Except for the Lyon Heart
Study, most of the cardiovascular disease omega-3 fatty
acids supplementation trials did not attempt to modify the
consumption of other fat components, and speciﬁcally did
not seek to reduce the intake of omega-6 fatty acids despite
the fact that there is convincing support for such studies.
The differences in the omega-6/omega-3 ratio in the
background diets and the dose of EPA and DHA could be
an important factor in studies with conﬂicting results in
intervention trials on the role of EPA and DHA in patients
with ventricular arrhythmias in which a beneﬁcial effect was
shown by Leaf et al. (85) but not by Raitt et al. (86).
Yokoyama et al. investigated the effects of EPA on
major coronary events in hypercholesterolemic patients in a
randomized open label, blinded analysis (87). Patients were
randomly assigned to receive either 1800 mg of EPA with
statin or statin only in a 5-year follow up. The results
showed that EPA is a promising treatment for prevention of
major coronary events, and especially nonfatal coronary
events, in Japanese hypercholesterolemic patients. This is a
very important ﬁnding because the Japanese already have a
high ﬁsh intake. These ﬁndings further support the data
from the study by Iso et al. that showed, compared with a
modest ﬁsh intake of once a week or about 20 g/d, a higher
intake was associated with substantially reduced risk of
coronary heart disease, primarily nonfatal cardiac events,
among middle aged persons (88).
The importance of balancing the LA (omega-6) to ALA
(omega-3) ratio was shown in a randomized, controlled, 3-
diet, 3-period crossover study in which 22 hypercholester-
olemic subjects were assigned to 3 experimental diets: a diet
high in ALA (ALA diet; 6.5% of energy) a diet high in LA
(LA diet; 12.6% of energy), and an average American diet
(AAD) for 6 weeks (89). Serum IL-6, IL-1b, and TNF-a
concentrations and the production of IL-6, IL-1b, and TNF-
a by peripheral blood mononuclear cells (PBMCs) were
measured. The ratio of omega-6/omega-3 was 10/1 in AAD,
4.1/1 in the LA diet and 2/1 in the ALA diet. The results
showed that on the ALA diet, IL-6, IL-1b, and TNF-a
production by PBMCs and serum TNF-a concentrations
were lower (P , 0.05 and P , 0.08 respectively) than with
the LA diet or AAD. PBMC production of TNF-a was
inversely correlated with ALA (P ¼ 0.07) and with
eicosapentaenoic acid (P ¼ 0.03) concentrations in PBMC
lipids with the ALA diet. Changes in serum ALA were
inversely correlated with changes in TNF-a produced by
PBMCs (P , 0.05). In this study the increased intake of
dietary ALA elicited anti-inﬂammatory effects by inhibiting
IL-6, IL-1b, and TNF-a production in cultured PBMCs.
Changes in PBMC ALA and EPA derived from ALA are
associated with beneﬁcial changes in TNF-a release. The
cardioprotective effects of ALA are mediated in part by a
reduction in the production of inﬂammatory cytokines, IL-6,
IL-1b, and TNF-a (60, 90). Other studies, in which the ratio
of LA/ALA was not balanced, failed to decrease CRP or IL-
6, IL-1b, or TNF-a (91), leading to wrong conclusions that
LA is not inﬂammatory, despite the fact that it has been
shown by Toborek et al. in 2002 (92). These results are
important because they strongly suggest that the ALA intake
at a ratio of 1–2/1—which is simple to implement, as shown
by Paschos et al. (90) and Zampelas et al. (60)—could lead
to an anti-inﬂammatory state, which is beneﬁcial to health
and reduce the risk for heart disease beyond that achieved
from lower LDL concentrations alone.
Studies carried out in India indicate that the higher ratio
of 18:2x6 to 18:3x3 equaling 20/1 in their food supply led
to increases in the prevalence of non-insulin diabetes
mellitus (NIDDM) in the population, whereas a diet with
a ratio of 6/1 prevented the increase in NIDDM (93).
James and Cleland have reported beneﬁcial effects in
patients with rheumatoid arthritis (94) and Broughton has
shown beneﬁcial effects in patients with asthma by
changing the background diet (95). James and Cleland
evaluated the potential use of omega-3 fatty acids within a
dietary framework of an omega-6/omega-3 ratio of 3–4/1 by
supplying 4 gm of EPAþDHA and using ﬂaxseed oil rich in
ALA. In their studies, the addition of 4 gm EPA and DHA
in the diet produced a substantial inhibition of production of
IL-1b and TNFa when mononuclear cell levels of EPA were
equal or greater than 1.5% of total cell phospholipid fatty
acids which correlated with a plasma phospholipid EPA
level equal to or greater than 3.2%. These studies suggest
the potential for complementarity between drug therapy and
dietary choices that increased intake of omega-3 fatty acids
and decreased intake of omega-6 fatty acids may lead to
drug-sparing effects. Therefore, future studies need to
address the fat composition of the background diet, and
the issue of concurrent drug use. A diet rich in omega-3
fatty acids and poor in omega-6 fatty acids provides the
appropriate background biochemical environment in which
Asthma is a mediator driven inﬂammatory process in
the lungs and the most common chronic condition in
childhood. The leukotrienes and prostaglandins are impli-
cated in the inﬂammatory cascade that occurs in asthmatic
airways. There is evidence of airway inﬂammation even in
newly diagnosed asthma patients within 2–12 months after
their ﬁrst symptoms (96). Among the cells involved in
asthma are mast cells, macrophages, eosinophils, and
lymphocytes. The inﬂammatory mediators include cyto-
kines and growth factors (peptide mediators) as well as the
eicosanoids, which are the products of AA metabolism,
which are important mediators in the underlying inﬂamma-
tory mechanisms of asthma (Table 8; Fig. 3). Leukotrienes
and prostaglandins appear to have the greatest relevance to
the pathogenesis of asthma. The leukotrienes are potent
inducers of bronchospasm, airway edema, mucus secretion,
and inﬂammatory cell migration, all of which are important
to the asthmatic symptomatology. Broughton et al. (95)
studied the effect of omega-3 fatty acids at a ratio of omega-
6/omega-3 of 10/1 to 5/1 in an asthmatic population in
ameliorating methacholine-induced respiratory distress.
With low omega-3 ingestion, methacholine-induced respi-
ratory distress increased. With high omega-3 fatty acid
ingestion, alterations in urinary 5-series leukotriene ex-
cretion predicted treatment efﬁcacy and a dose change in
.40% of the test subjects (responders) whereas the non-
responders had a further loss in respiratory capacity. A
urinary ratio of 4-series to 5-series of ,1 induced by
omega-3 fatty acid ingestion may predict respiratory beneﬁt.
Bartram et al. (97, 98) carried out two human studies in
which ﬁsh oil supplementation was given in order to
suppress rectal epithelial cell proliferation and prostaglandin
) biosynthesis. This was achieved when the dietary
omega-6/omega-3 ratio was 2.5/1 but not with the same
absolute level of ﬁsh oil intake and an omega-6/omega-3
ratio of 4/1. More recently, Maillard et al. reported their
results on a case control study (99). They determined
omega-3 and omega-6 fatty acids in breast adipose tissue
and relative risk of breast cancer. They concluded, ‘‘Our
data based on fatty acid levels in breast adipose tissue
(which reﬂect dietary intake) suggest a protective effect of
omega-3 fatty acids on breast cancer risk and support the
hypothesis that the balance between omega-3 and omega-6
fatty acids plays a role in breast cancer.’’ In a case-control
study in Shanghai, China on the relationship between fatty
acids and breast cancer, Shannon et al. concluded, ‘‘Our
results support a positive effect of omega-3 fatty acids on
breast cancer risk and provide additional evidence for the
importance of evaluating the ratio of fatty acids when
evaluating diet and breast cancer risk (20).’’
Osteoporosis represents a major challenge to health
care services, particularly with increases in the elderly
population worldwide. Bone mineral accrual during child-
hood and adolescence plays a vital role in preventing
osteoporosis. The identiﬁcation of factors inﬂuencing peak
bone mass is important for the prevention of osteoporosis
and related fractures. Genetic factors are responsible for
about 70% of the variance in bone mass (100, 101). Other
factors include nutrition, physical activity, and body mass
index (BMI) (102). Animal studies have shown that dietary
intake of long-chain omega-3 fatty acids may inﬂuence both
bone formation and bone resorption (103, 104) and an
increase in periosteal bone formation (105, 106).
The dietary ratio of omega-6/omega-3 fatty acids and
bone mineral density in older adults was studied in the
Rancho Bernardo Study by Weiss et al. (107). The study
was carried out in 1532 community-dwelling men and
women aged 45–90 years, between 1988 and 1992. The
average intake of total omega-3 fatty acids was 1.3 g/d and
the average ratio of total omega-6/omega-3 fatty acids was
8.4 in men and 7.9 in women. There was a signiﬁcant
inverse association between the ratio of dietary LA to ALA
and bone mineral density (BMD) at the hip in 642 men, 564
women not using hormone therapy, and 326 women using
hormone therapy. The results were independent of age, body
mass index, and lifestyle factors. An increasing ratio of total
dietary omega-6/omega-3 fatty acids was also signiﬁcant
OMEGA-6/OMEGA-3 FATTY ACID RATIO 683
and independently associated with lower BMD at the hip in
all women and at the spine in women not using hormone
therapy. Thus, the relative amounts of dietary omega-6 and
omega-3 fatty acids may play a vital role in preserving
skeletal integrity of old age.
The study by Hogstrom et al. is unique in that it
measured serum fatty acid concentrations rather than use a
dietary recall questionnaire to determine fatty acid intake
(108). The aim of the 8-year prospective and retrospective
study was to investigate a possible role of fatty acids in bone
accumulation and the attainment of peak bone mass in
young postpubertal men. Key ﬁndings show a positive
association between omega-3 fatty acids and BMD of the
total body and spine, and the accumulation of BMD at the
spine between 16 and 22 years of age in the cohort of
healthy young men. This study is the ﬁrst to examine the
association between individual PUFAs, BMD, and bone
mineral accrual. In summary, BMD of the total body
measured at 22 years of age showed a signiﬁcant negative
correlation with serum concentrations of oleic acid and
monounsaturated fatty acids, and a signiﬁcant positive
correlation with DHA and omega-3 fatty acids. BMD of the
spine measured at 22 years of age showed a positive
association with DHA and omega-3 fatty acids. Changes in
BMD of the spine between 16 and 22 years of age showed a
positive association with DHA and omega-3 fatty acids, and
a negative association with the omega-6/omega-3 ratio
The study by Hogstrom et al. (108) adds to the growing
body of evidence that omega-3 fatty acids are beneﬁcial to
bone health. Animal models have suggested that omega-3
fatty acids may attenuate postmenopausal bone loss.
Ovariectomized mice fed a diet high in ﬁsh oil had
signiﬁcantly less bone loss at the femur and lumbar
vertebrae than did ovariectomized mice fed a diet high in
omega-6 fatty acids (109). In vitro models using a
preosteoblastic cell line, MC3T3-E1, indicated a greater
production of the bone-formation markers alkaline phos-
phatase and osteocalcin after 48 hours of treatment with
EPA than after treatment with ALA (110).
Omega-3 fatty acids play an important role in health
and disease and favorably affect skeletal growth. The
attainment of peak bone mass in adolescence and the
prevention of age-related osteoporosis are potential positive
effects of omega-3 fatty acids.
Psychologic stress in humans induces the production of
proinﬂammatory cytokines such as interferon gamma
(IFNc), TNFa, IL-6 and IL-1. An imbalance of omega-6
and omega-3 PUFA in the peripheral blood causes an
overproduction of proinﬂammatory cytokines. There is
evidence that changes in fatty acid composition are involved
in the pathophysiology of major depression (111). Changes
in serotonin (5-HT) receptor number and function caused by
changes in PUFA provide the theoretical rationale connect-
ing fatty acids with the current receptor and neurotransmitter
theories of depression (112–116). The increased C20:4x6/
C20:5x3 ratio and the imbalance in the omega-6/omega-3
PUFA ratio in major depression may be related to the
increased production of proinﬂammatory cytokines and
eicosanoids in that illness (114). There are a number of
studies evaluating the therapeutic effect of EPA and DHA in
major depression. Stoll and colleagues have shown that
EPA and DHA prolong remission, that is, reduce the risk of
relapse in patients with bipolar disorder (117, 118).
Kiecolt-Glaser et al. studied depressive symptoms,
omega-6/omega-3 fatty acid ratio and inﬂammation in older
adults (119). As the dietary ratio of omega-6/omega-3
increased, the depressive symptoms, TNF-a, IL-6, and IL-6
soluble receptor (sIL-6r) increased. The authors concluded
that diets with a high omega-6/omega-3 ratio may enhance
the risk for both depression and inﬂammatory diseases.
Dry eye syndrome (DES) is one of the most prevalent
conditions. Inﬂammation of the lacrimal gland, the
meibomian gland, and the ocular surface plays a signiﬁcant
role in DES (120, 121). Increased concentration of
inﬂammatory cytokines, such as IL-1, IL-6, and TNFa
have been found in tear ﬁlm in patients with DES (122).
Miljanovic et al. investigated the relation of dietary intake
of omega-3 fatty acids and the ratio of omega-6 to omega-3
with DES incidence in a large population of women
participating in the Women’s Health Study (123). A higher
ratio of omega-6/omega-3 consumption was associated with
a signiﬁcantly increased risk of DES (OR: 2.51; 95% CI:
1.13, 5.58) for .15:1 versus ,4.1 (P for trend ¼ 0.01).
These results suggest that a higher dietary intake of omega-3
fatty acids is associated with a decreased incidence of DES
in women and a high omega-6/omega-3 ratio is associated
with a greater risk.
Age-related macular degeneration (AMD) is the leading
cause of vision loss among people 65 and older. Both AMD
and cardiovascular disease share similar modiﬁable factors
(124–128). Fish intake has been reported to have protective
properties in lowering the risk of AMD (129–133),
especially when LA intake was low (129, 130). In a study
involving twins, Seddon et al. showed that ﬁsh consumption
and omega-3 fatty acid intake reduce the risk of AMD
whereas cigarette smoking increases the risk for AMD
Conclusions and Recommendations
Western diets are characterized by high omega-6 and
low omega-3 fatty acid intake, whereas during the
Paleolithic period when human’s genetic proﬁle was
established, there was a balance between omega-6 and
omega-3 fatty acids. Therefore, humans today live in a
nutritional environment that differs from that for which our
genetic constitution was selected.
The balance of omega-6/omega-3 fatty acids is an
important determinant in decreasing the risk for coronary
heart disease, both in the primary and secondary prevention
of coronary heart disease.
Increased dietary intake of LA leads to oxidation of
LDL, platelet aggregation, and interferes with the incorpo-
ration of EPA and DHA in cell membrane phospholipids.
Both omega-6 and omega-3 fatty acids inﬂuence gene
expression. EPA and DHA have the most potent anti-
inﬂammatory effects. Inﬂammation is at the base of many
chronic diseases, including coronary heart disease, diabetes,
arthritis, cancer, osteoporosis, mental health, dry eye disease
and age-related macular degeneration. Dietary intake of
omega-3 fatty acids may prevent the development of
disease, particularly in persons with genetic variation, as
for example in individuals with genetic variants at the 5-LO
and the development of coronary heart disease.
Chronic diseases are multigenic and multifactorial. It is
quite possible that the therapeutic dose of omega-3 fatty
acids will depend on the degree or severity of disease
resulting from the genetic predisposition.
In carrying out clinical intervention trials, it is essential
to increase the omega-3 and decrease the omega-6 fatty acid
intake in order to have a balanced omega-6 and omega-3
intake in the background diet. Both the dietary intake and
plasma levels should be determined before and after the
1. Simopoulos AP, Childs B (Eds.). Genetic Variation and Nutrition.
World Rev Nutr Diet. Basel: Karger, Vol. 63, 1990.
2. Simopoulos AP, Robinson J. The Omega Diet. The Lifesaving
Nutritional Program Based on the Diet of the Island of Crete. New
York: HarperCollins, 1999.
3. Simopoulos AP, Nestel PJ (Eds.). Genetic Variation and Dietary
Response. World Rev Nutr Diet. Basel: Karger, Vol. 80, 1997.
4. Simopoulos AP, Pavlou KN (Eds.). Nutrition and Fitness 1: Diet,
Genes, Physical Activity and Health. World Rev Nutr Diet. Basel:
Karger, Vol. 89, 2001.
5. Simopoulos AP. Genetic variation and dietary response: nutrigenet-
ics/nutrigenomics. Asia Paciﬁc J Clin Nutr 11(S6):S117–S128, 2002.
6. Simopoulos AP, Ordovas JM (Eds.). Nutrigenetics and Nutrigenom-
ics. World Rev Nutr Diet. Basel: Karger, Vol. 93, 2004.
7. Eaton SB, Konner M. Paleolithic nutrition. A consideration of its
nature and current implications. New Engl J Med 312:283–289, 1985.
8. Simopoulos AP. Omega-3 fatty acids in health and disease and in
growth and development. Am J Clin Nutr 54:438–463, 1991.
9. Simopoulos AP. Genetic variation and evolutionary aspects of diet. In:
Papas A, Ed. Antioxidants in Nutrition and Health. Boca Raton: CRC
Press, pp65–88, 1999.
10. Simopoulos AP. Evolutionary aspects of omega-3 fatty acids in the
food supply. Prostaglandins, Leukotr Essent Fatty Acids 60:421–429,
11. Simopoulos AP. New products from the agri-food industry: The return
of n-3 fatty acids into the food supply. Lipids 34(suppl):S297–S301,
12. Eaton SB, Konner M, Shostak M. Stone agers in the fast lane: chronic
degenerative diseases in evolutionary perspective. Am J Med 84:739–
13. Eaton SB, Eaton SB III, Sinclair AJ, Cordain L, Mann NJ. Dietary
intake of long-chain polyunsaturated fatty acids during the Paleolithic.
World Rev Nutr Diet 83:12–23, 1998.
14. Leaf A, Weber PC. A new era for science in nutrition. Am J Clin Nutr
15. Simopoulos AP. Overview of evolutionary aspects of w3 fatty acids in
the diet. World Rev Nutr Diet 83:1–11, 1998.
16. Weber PC. Are we what we eat? Fatty acids in nutrition and in cell
membranes: cell functions and disorders induced by dietary
conditions. Svanoybukt, Norway: Svanoy Foundation (Report no.
4), pp9–18, 1989.
17. Simopoulos AP. Evolutionary aspects of diet: fatty acids, insulin
resistance and obesity. In: VanItallie TB, Simopoulos AP, Sr. Eds.
Obesity: New Directions in Assessment and Management. Philadel-
phia: Charles Press, pp241–261, 1995.
18. Simopoulos AP. Trans fatty acids. In: Spiller GA, Ed. Handbook of
Lipids in Human Nutrition. Boca Raton: CRC Press, pp91–99, 1995.
19. Simopoulos AP. Omega-3 fatty acids in inﬂammation an autoimmune
diseases. J Am Coll Nutr 21:495–505, 2002.
20. Shannon J, King IB, Moshofskky R, Lampe JW, Li Gao D, Ray RM,
Thomas DB. Erythrocyte fatty acids and breast cancer risk: a case-
control study in Shanghai, China. Am J Clin Nutr 85:1090–1097,
21. Hughes-Fulford M, Tjandrawinata RR, Li CF, Sayyah S. Arachidonic
acid, an omega-6 fatty acid, induces cytoplasmic phospholipase A2 in
prostate carcinoma cells. Carcinogenesis 26:1520–1526, 2005.
22. Hedelin M, Chang ET, Wiklund F, Bellocco R, Klint A, Adolfsson J,
Shahedi K, Xu J, Adami HO, Gronberg H, Balter KA. Association of
frequent consumption of fatty ﬁsh with prostate cancer risk is modiﬁed
by COX-2 polymorphism. Int J Cancer 120:398–405, 2007.
23. Hunter JE. Omega-3 fatty acids from vegetable oils. In: Galli C,
Simopoulos AP, Eds. Biological Effects and Nutritional Essentiality.
Series A: Life Sciences. New York: Plenum Press, Vol. 171:pp43–55,
24. Litin L, Sacks F. Trans-fatty-acid content of common foods. N Engl J
Med 329:1969–1970, 1993.
25. Raper NR, Cronin FJ, Exler J. Omega-3 fatty acid content of the US
food supply. J Am College Nutr 11:304, 1992.
26. Ledger HP. Body composition as a basis for a comparative study of
some East African animals. Symp Zool Soc London 21:289–310,
27. Crawford MA. Fatty acid ratios in free-living and domestic animals.
Lancet i:1329–1333, 1968.
28. Crawford MA, Gale MM, Woodford MH. Linoleic acid and linolenic
acid elongation products in muscle tissue of Syncerus caffer and other
ruminant species. Biochem J 115:25–27, 1969.
29. Simopoulos AP, Norman HA, Gillaspy JE, Duke JA. Common
purslane: a source of omega-3 fatty acids and antioxidants. J Am
College Nutr 11:374–382, 1992.
30. Simopoulos AP, Norman HA, Gillaspy JE. Purslane in human
nutrition and its potential for world agriculture. Basel: Karger, World
Rev Nutr Diet 77:47–74, 1995.
31. Simopoulos AP, Salem N Jr. Purslane: a terrestrial source of omega-3
fatty acids. N Engl J Med 315:833, 1986.
32. Simopoulos AP, Gopalan C (Eds.). Plants in Human Health and
Nutrition Policy. World Rev Nutr Diet. Basel: Karger, Vol. 91, pp47–
33. Zeghichi S, Kallithrka S, Simopoulos AP, Kypriotakis Z. Nutritional
composition of selected wild plants in the diet of Crete. World Rev
Nutr Diet 91:22–40, 2003.
34. Simopoulos AP. Omega-3 fatty acids in wild plants, seeds and nuts.
Asian Paciﬁc J Clin Nutr 11(S6):S163–S173, 2002.
35. Simopoulos AP. Omega-3 fatty acids and antioxidants in edible wild
plants. Biological Research 37(2):263–277, 2004.
36. Simopoulos AP, Salem N Jr. n-3 fatty acids in eggs from range-fed
Greek chickens. N Engl J Med 321:1412, 1989.
37. Simopoulos AP, Salem N Jr. Egg yolk as a source of long-chain
polyunsaturated fatty acids in infant feeding. Am J Clin Nutr 55:411–
OMEGA-6/OMEGA-3 FATTY ACID RATIO 685
38. van Vliet T, Katan MB. Lower ratio of n-3 to n-6 fatty acids in
cultured than in wild ﬁsh. Am J Clin Nutr 51:1–2, 1990.
39. Cordain L, Martin C, Florant G, Watkins BA. The fatty acid
composition of muscle, brain, marrow and adipose tissue in elk:
evolutionary implications for human dietary requirements. World Rev
Nutr Diet. Basel:Karger, Vol. 83, p. 225, 1998.
40. Sinclair AJ, Slattery WJ, O’Dea K. The analysis of polyunsaturated
fatty acids in meat by capillary gas-liquid chromotography. J Food Sci
Agric 33:771–776, 1982.
41. Sugano M, Hirahara F. Polyunsaturated fatty acids in the food chain in
Japan. Am J Clin Nutr 71(suppl):189S–196S, 2000.
42. Pella D, Dubnov G, Singh RB, Sharma R. Effects of an Indo-
Mediterranean diet on the omega-6/omega-3 ratio in patients at high
risk of coronary artery disease: the Indian paradox. Basel: Karger,
World Rev Nutr Diet 92:74–80, 2003.
43. Sanders TAB. Polyunsaturated fatty acids in the food chain in Europe.
Am J Clin Nutr 71(suppl):S176–S178, 2000.
44. de Gomez Dumm INT, Brenner RR. Oxidative desaturation of alpha-
linolenic, linoleic, and stearic acids by human liver microsomes.
Lipids 10:315–317, 1975.
45. Emken EA, Adlof RO, Rakoff H, Rohwedder WK. Metabolism of
deuterium-labeled linolenic, linoleic, oleic, stearic and palmitic acid in
human subjects. In: Baillie TA, Jones JR, Eds. Synthesis and
Application of Isotopically Labeled Compounds 1988. Amsterdam:
Elsevier Science Publishers, 713–716, 1989.
46. Hague TA, Christoffersen BO. Effect of dietary fats on arachidonic
acid and eicosapentaenoic acid biosynthesis and conversion to C22
fatty acids in isolated liver cells. Biochim Biophys Acta 796:205–217,
47. Hague TA, Christoffersen BO. Evidence for peroxisomal retrocon-
version of adrenic acid (22:4n6) and docosahexaenoic acid (22:6n3) in
isolated liver cells. Biochim Biophys Acta 875:165–173, 1986.
48. Indu M, Ghafoorunissa. N-3 fatty acids in Indian diets—comparison
of the effects of precursor (alpha-linolenic acid) vs product (long chain
n-3 polyunsaturated fatty acids). Nutr Res 12:569–582, 1992.
49. Carlson SE, Rhodes PG, Ferguson MG. Docosahexaenoic acid status
of preterm infants at birth and following feeding with human milk or
formula. Am J Clin Nutr 44:798–804, 1986.
50. Singer P, Jaeger W, Voigt S, Theil H. Defective desaturation and
elongation of n-6 and n-3 fatty acids in hypertensive patients.
Prostaglandins Leukot Med 15:159–165, 1984.
51. Honigmann G, Schimke E, Beitz J, Mest HJ, Schliack V. Inﬂuence of
a diet rich in linolenic acid on lipids, thrombocyte aggregation and
prostaglandins in type I (insulin-dependent) diabetes. Diabetologia 23:
52. Simopoulos AP. Essential fatty acids in health and chronic disease.
Am J Clin Nutr 70(suppl):560S–569S, 1999.
53. Parthasarathy S, Khoo JC, Miller E, Barnett J, Witztum JL, Steinberg
D. Low density lipoprotein rich in oleic acid is protected against
oxidative modiﬁcation: implications for dietary prevention of athero-
sclerosis. Proc Natl Acad Sci USA 87:3894–3898, 1990.
54. Reaven P, Parthasarathy S, Grasse BJ, Miller E, Almazan F, Mattson
FH, Khoo JC, Steinberg D, Witztum JL. Feasibility of using an oleate-
rich diet to reduce the susceptibility of low density lipoprotein to
oxidative modiﬁcation in humans. Am J Clin Nutr 54:701–706, 1991.
55. Reaven PD, Grasse BJ, Tribble DL. Effects of linoleate-enriched and
oleate-enriched diets in combination with a-tocopherol on the
susceptibility of LDL and LDL subfractions to oxidative modiﬁcation
in humans. Arterioscler Thromb 14:557–566, 1994.
56. Louheranta AM, Porkkala-Sarataho EK, Nyyssonen MK, Salonen
RM, Salonen JT. Linoleic acid intake and susceptibility of very-low-
density and low-density lipoproteins to oxidation in men. Am J Clin
Nutr 63:698–703, 1996.
57. Regnstrom J, Nilsson J, Tornvall P, Landou C, Hamsten A.
Susceptibility to low-density lipoprotein oxidation and coronary
atherosclerosis in man. Lancet 339:1183–1186, 1992.
58. Cleland LG, James MJ, Neumann MA, D’Angelo M, Gibson RA.
Linoleate inhibits EPA incorporation from dietary ﬁsh-oil supple-
ments in human subjects. Am J Clin Nutr 55:395–399, 1992.
59. Liou YA, King J, Zibrik D, Innis SM. Decreasing linoleic acid with
constant a-linolenic acid in dietary fats increases (n-3) eicosapenta-
enoic acid in plasma phospholipids in healthy men. J Nutr 137:945–
60. Zampelas A, Paschos G, Rallidis L, Yiannakouris N. Linoleic acid to
alpha-linolenic acid ratio. From clinical trials to inﬂammatory markers
of coronary artery disease. World Rev Nutr Diet 92:92–108, 2003.
61. Ambring A, Johansson M, Axelsen M, Gan L, Strandvik B, Friberg P.
Mediterranean-inspired diet lowers the ratio of serum phospholipid n-
6 to n-3 fatty acids, the number of leukocytes and platelets, and
vascular endothelial growth factor in healthy subjects. Am J Clin Nutr
62. Simopoulos AP, Visioli F (Eds.). Mediterranean Diets. World Rev
Nutr Diet. Basel: Karger, Vol. 87, 2000.
63. Simopoulos AP, Visioli F (Eds.). More on Mediterranean Diets.
World Rev Nutr Diet. Basel: Karger, Vol. 95, 2007.
64. Freese R, Mutanen M, Valsta LM, Salminen I. Comparison of the
effects of two diets rich in monounsaturated fatty acids differing in
their linoleic/alpha-linolenic acid ratio on platelet aggregation.
Thromb Haemost 71:73–77, 1994.
65. Simopoulos AP, Cleland LG (Eds.). Omega-6/Omega-3 Essential
Fatty Acid Ratio: The scientiﬁc evidence. World Rev Nutr Diet. Basel:
Karger, Vol. 92, 2003.
66. Ferruci L, Cherubini A, Bandinelli S, Bartali B, Corsi A, Lauretani F,
Martin A, Andres-Lacueva C, Senin U, Guralnik JM. Relationship of
plasma polyunsaturated fatty acids to circulating inﬂammatory
markers. J Clin Endocrinol Metab 91:439–446, 2006.
67. Kang ZB, Ge Y, Chen Z, Brown J, Lapasota M, Leaf A, Kang JX.
Adenoviral transfer of Caenorhabditis elegans n-3 fatty acid
desaturase optimizes fatty acid composition in mammalian heart
cells. Proc Natl Acad Sci USA 98:4050–4054, 2001.
68. Ge Y-L, Chen Z, Kang ZB, Cluette-Brown J, Laposata M, Kang JX.
Effects of adenoviral transfer of Caenorhabditis elegans n-3 fatty acid
desaturase on the lipid proﬁle and growth of human breast cancer
cells. Anticancer Research 22:537–544, 2002.
69. Kang JX. The importance of omega-6/omega-3 fatty acid ratio in cell
function. The gene transfer of omega-3 fatty acid desaturase. World
Rev Nutr Diet 92:23–36, 2003.
70. Kang JX, Wang J, Wu L, Kang ZB. Fat-1 mice convert n-6 to n-3 fatty
acids. Nature 427:504, 2004.
71. Kang JX. Balance of omega-6/omega-3 fatty acids is important for
health: the evidence from gene transfer studies. World Rev Nutr Diet
72. Lai L, Kang JX, Li R, Wang J, Witt WT, Yong HY, Hao Y, Was DM,
Murphy CN, Rieke A, Samuel M, Linville ML, Korte SW, Evans RW,
Starzl TE, Prather RS, Dai Y. Generation of cloned transgenic pigs
rich in omega-3 fatty acids. Nat Biotechnol 4:435–436, 2006.
73. Kang JX. Fat-1 transgenic mice: a new model for omega-3 research.
Prostaglandins Leukot Essent Fatty Acids 77:263–267, 2007.
74. Simopoulos AP. The role of fatty acids in gene expression: health
implications. Ann Nutr Metab 40:303–311, 1996.
75. Dwyer JH, Allayee H, Dwyer KM, Fan J, Wu H, Mar R, Lusis AJ,
Mehrabian M. Arachidonate 5-lipoxygenase promoter genotype,
dietary arachidonic acid, and atherosclerosis. N Engl J Med 350:29–
76. de Lorgeril M, Renaud S, Mamelle N, Salen P, Martin J-L, Monjaud I,
Guidollet J, Touboul P, Delaye J. Mediterranean alpha-linolenic acid-
rich diet in secondary prevention of coronary heart disease. Lancet
77. Renaud S, de Lorgeril M, Delaye J, Guidollet J, Jacquard F, Mamelle
N, Martin JL, Monjaud I, Salen P, Toubol P. Cretan Mediterranean
diet for prevention of coronary heart disease. Am J Clin Nutr
78. de Lorgeril M, Salen P. Modiﬁed Cretan Mediterranean diet in the
prevention of coronary heart disease and cancer. World Rev Nutr Diet
79. de Lorgeril M, Salen P. Modiﬁed Cretan Mediterranean diet in the
prevention of coronary heart disease and cancer. An update. World
Rev Nutr Diet 97:1–32, 2007.
80. GISSI-Prevenzione Investigators. Dietary supplementation with n-3
polyunsaturated fatty acids and vitamin E after myocardial infarction:
results of the GISSI-Prevenzione trial. Lancet 354:447–455, 1999.
81. Li Y, Kang JX, Leaf A. Differential effects of various eicosanoids on
the contraction of cultured neonatal rat cardiomyocytes. Prostaglan-
dins 54:511–530, 1997.
82. Burr ML, Fehily AM, Gilbert JF, Rogers S, Holliday RM, Sweetnam
PM, Elwood PC, Deadman NM. Effect of changes in fat, ﬁsh and ﬁbre
intakes on death and myocardial reinfarction: diet and reinfarction trial
(DART). Lancet 2:757–761, 1989.
83. Singh RB, Rastogi SS, Verma R, Laxmi B, Singh R, Ghosh S, Niaz
MA. Randomized controlled trial of cardioprotective diet in patients
with recent acute myocardial infarction: results of one year follow up.
BMJ 304:1015–1019, 1992.
84. Singh RB, Niaz MA, Sharma JP, Kumar R, Rastogi V, Moshiri M.
Randomized, double-blind, placebo-controlled trial of ﬁsh oil and
mustard oil in patients with suspected acute myocardial infarction: the
Indian experiment of infarct survival—4. Cardiovasc Drugs Ther 11:
85. Leaf A, Albert CM, Josephson M, Steinhaus D, Kluger J, Kang JX,
Cox B, Zhang H, Schoenfeld D, Fatty Acid Antiarrhymnia Trial
Investigators. Prevention of fatal arrhythmias in high-risk subjects by
ﬁsh oil n-3 fatty acid intake. Circulation 112:2762–2768, 2005.
86. Raitt MH, Connor WE, Morris C, Kron J, Halperin B, Chugh SS,
McClelland J, Cook J, MacMurdy K, Swenson R, Connor SL,
Gerhard G, Kraemer DF, Oseran D, Marchant C, Calhoun D, Shnider
R, McAnulty J. Fish oil supplementation and risk of ventricular
tachycardia and ventricular ﬁbrillation in patients with implantable
deﬁbrilators. A randomized controlled trial. JAMA 293:2884–2891,
87. Yokoyama M, Origasa H, Matsuzaki M, Matsuzawa Y, Saito Y,
Ishikawa Y, Oikawa S, Sasaki J, Hishida H, Itakura H, Kita T,
Kitabatake A, Nakaya N, Sakata T, Shimoda K, Shirata K, for the
Japan EPA lipid intervention study (JELIS) Investigation. Effects of
eicosapentaenoic acid on major coronary events in hypercholester-
olaemic patients (JELIS): a randomised open-label, blinded endpoint
analysis. Lancet 369:1090–1098, 2007.
88. Iso H, Kobayashi M, Ishihara J, Sasaki S, Okada K, Kita Y, Kokubo
Y, Tsugane S; JPHC Study Group: Intake of ﬁsh and n3 fatty acids
and risk of coronary heart disease among Japanese. The Japan Public
Health Center-Based (JPHC) Study Cohort I. Circulation 113:195–
89. Zhao G, Etherton TD, Martin KR, Gillies PJ, West SG, Kris-Etherton
PM. Dietary a-linolenic acid inhibits proinﬂammatory cytokine
production by peripheral blood mononuclear cells in hypercholester-
olemic subjects. Am J Clin Nutr 85:385–391, 2007.
90. Paschos GK, Magkos F, Panagiotakos DB, Votteas V, Zampelas A.
Dietary supplementation with ﬂaxseed oil lowers blood pressure in
dyslipidaemic patients. Eur J Clin Nutr. advance online publication 31
January 2007; doi: 10.1038/sj.ejcn.1602631:1–6, 2007.
91. Kew S, Banerjee T, Minihane AM, Finnegan YE, Muggli R, Albers R,
Williams CM, Calder PC. Lack of effect of foods enriched with plant-
or animal-derived n-3 fatty acids on human immune function. Am J
Clin Nutr 77:1287–1295, 2003.
92. Toborek M, Lee YW, Garrido R, Kaiser S, Hennig B. Unsaturated
fatty acids selectively induce an inﬂammatory environment in human
endothelial cells. Am J Clin Nutr 75:119–125, 2002.
93. Raheja BS, Sadikot SM, Phatak RB, Rao MB. Signiﬁcance of the n-
6/n-3 ratio for insulin action in diabetes. Ann NY Acad Sci 683:258–
94. James MJ, Cleland LG. Dietary n-3 fatty acids and therapy for
rheumatoid arthritis. Semin Arthritis Rheum 27:85–97, 1997.
95. Broughton KS, Johnson CS, Pace BK, Liebman M, Kleppinger KM.
Reduced asthma symptoms with n-3 fatty acid ingestion are related to
5-series leukotriene production. Am J Clin Nutr 65:1011–1017, 1997.
96. Laitinen LA, Laitinen A, Haahtela T. Airway mucosal inﬂammation
even in patients with newly diagnosed asthma. Am Rev Respir Dis
97. Bartram H-P, Bostner A, Scheppach W, Reddy BS, Rao CV, Dusel G,
Richter F, Richteer A, Kasper H. Effects of ﬁsh oil on rectal cell
proliferation, mucosal fatty acids, and prostaglandin E
healthy subjects. Gastroenterology 105:1317–1322, 1993.
98. Bartram H-P, Gostner A, Reddy BS, Rao CV, Scheppach W, Dusal G,
Richter A, Richter F, Kasper H. Missing anti-proliferative effect of
ﬁsh oil on rectal epithelium in healthy volunteers consuming a high-
fat diet: potential role of the n-3:n-6 fatty acid ratio. Eur J Cancer Prev
99. Maillard V, Bougnoux P, Ferrari P, Jourdan M-L, Pinault M,
Lavillonnieree FF, Body G, Le Floch O, Chajes V. N-3 and n-6 fatty
acids in breast adipose tissue and relative risk of breast cancer in a
case-control study in Tours, France. Int J Cancer 98:78–83, 2002.
100. Eisman JA. Genetics of osteoporosis. Endocr Rev 20:788–894, 1999.
101. Seeman H, Hopper JL, Bach LA, Cooper ME, Parkinson E, McKay J,
Jerums G. Reduced bone mass in daughters of women with
osteoporosis. N Engl J Med 320:554–558, 1989.
102. Cummings SR, Nevitt MC, Browner WS, Stone K, Fox KM, Ensrud
KE, Cauley J, Black D, Vogt TM. Risk factors for hip fracture in
white women. Study of Osteoporosis Fracture Research Group. N
Engl J Med 332:767–773, 1995.
103. Sakaguchi K, Morita I, Murota S. Eicosapentaenoic acid inhibits bone
loss due to ovariectomy in rats. Prostaglandins Leukot Essent Fatty
Acids 50:81–84, 1994.
104. Iwami-Morimoto Y, Yamaguchi K, Tanne K. Inﬂuence of dietary n-3
polyunsaturated fatty acid on experimental tooth movement in rats.
Angle Orthod 69:365–371, 1999.
105. Li Y, Seifert MF, Ney DM, Grahn M, Grant AL, Allen KG, Watkins
BA. Dietary conjugated linoleic acids alter serum IGF-1 and IGF
binding protein concentrations and reduce bone formation in rats fed
(n-6) or (n-3) fatty acids. J Bone Miner Res 14:1153–1162, 1999.
106. Das U. Interaction(s) between essential fatty acids, eicosanoids,
cytokines, growth factors and free radicals: relevance to new
therapeutic strategies in rheumatoid arthritis and other collagen
vascular diseases. Prostaglandins Leukot Essent Fatty Acids 44:
107. Weiss LA, Barret-Connor E, von Muhlen D. Ratio of n-6 to n-3 fatty
acids and bone mineral density in older adults: the Rancho Bernardo
Study. Am J Clin Nutr 81:934–938, 2005.
108. Hogstrom M, Nordstrom P, Nordstrom A. n-3 fatty acids are
positively associated with peak bone mineral density and bone accrual
in healthy men: the NO
study. Am J Clin Nutr 85:803–807, 2007.
109. Sun D, Krishnan A, Zaman K, Lawrence R, Bhattacharya A,
Fernandes G. Dietary n-3 fatty acids decrease osteoclastogenesis
and loss of bone mass in ovariectomized mice. J Bone Miner Res 18:
110. Watkins BA, Li Y, Lippman HE, Feng S. Modulatory effect of n-3
polyunsaturated fatty acids on osteoblast function and bone
metabolism. Prostaglandins Leukot Essent Fatty Acids 68:387–398,
111. Hibbeln JR, Salem N Jr. Dietary polyunsaturated fatty acids and
OMEGA-6/OMEGA-3 FATTY ACID RATIO 687
depression: when cholesterol does not satisfy. Am J Clin Nutr 62:1–9,
112. Hibbeln JR, Umhau JC, Linnoila M George DT, Ragan PW, Shoaf
SE, Vaughan MR, Rawlings R, Salem N Jr. A replication study of
violent and nonviolent subjects: cerebrospinal ﬂuid metabolites of
serotonin and dopamine are predicted by plasma essential fatty acids.
Biol Psychiatry 44:243–249, 1998.
113. Hibbeln JR, Linnoila M, Umhau JC, Rawlings R, George DT, Salem
N Jr. Essential fatty acids predict metabolites of serotonin and
dopamine in cerebrospinal ﬂuid among healthy control subjects, and
early- and late-onset alcoholics. Biol Psychiatry 44:235–242, 1998.
114. Maes M, Smith R, Christophe A, Cosyns P, Desnyder R, Meltzer H.
Fatty acid composition in major depression: decreased omega 3
fractions in cholesteryl esters and increased C20:4 omega 6/C20:5
omega 3 ratio in cholesteryl esters and phospholipids. J Affect Disord
115. Maes M, Smith R, Christophe A, Vandoolaeghe E, Van Gastel A,
Neels H, Demedts P, Wauters A, Meltzer HY. Lower serum high-
density lipoprotein cholesterol (HDL-C) in major depression and in
depressed men with serious suicidal attempts: relationship with
immune-inﬂammatory markers. Acta Psychiatr Scand 95:212–221,
116. Peet M, Murphy B, Shay J, Horrobin D. Depletion of omega-3 fatty
acid levels in red blood cell membranes of depressive patients. Biol
Psychiatry 43:315–319, 1998.
117. Locke CA, Stoll AL. Omega-3 fatty acids in major depression. World
Rev Nutr Diet 89:173–185, 2001.
118. Stoll AL, Severus WE, Freeman MP, Rueter S, Zboyan HA, Diamond
E, Cress KK, Marangell LB. Omega 3 fatty acids in bipolar disorder: a
preliminary double-blind, placebo-controlled trial. Arch Gen Psychia-
try 56:407–412, 1999.
119. Kiecolt-Glaser JK, Belury MA, Porter K, Beversdorf DQ, Lemeshow
S, Glaser R. Depressive symptoms, omega-6:omega-3 fatty acids, and
inﬂammation in older adults. Psychosom Med Mar 30; (Epub ahead of
120. Kunert KS, Tisdale AS, Stern ME, Smith JA, Gipson IK. Analysis of
topical cyclosporine treatment of patients with dry eye syndrome:
effect of conjunctival lymphocytes. Arch Ophthalmol 118:1489–1496,
121. Marsh P, Pﬂugfelder SC. Topical nonpreserved methylprednisolone
therapy for keratoconjuntivitis sicca in Sjogren syndrome. Ophthal-
mology 106:811–816, 1999.
122. Solomon A, Dursun D, Liu Z, Xie Y, Macri A, Pﬂugfelder SC. Pro-
and anti-inﬂammatory forms of interleukin-1 in the tear ﬂuid and
conjunctiva of patients with dry-eye disease. Invest Opthalmol Vis Sci
123. Miljanovic B, Trivedi KA, Dana MR, Gilbard JP, Buring JE,
Schaumberg DA. Relation between dietary n-3 and n-6 fatty acids and
clinically diagnosed dry eye syndrome in women. Am J Clin Nutr 82:
124. Snow KK, Seddon JM. Do age-related macular degeneration and
cardiovascular disease share common antecedents? Ophthalmic
Epidemiol 6:125–143, 1999.
125. Seddon JM, Chen CA. Epidemiology of age-related macular
degeneration (4th ed.). In: Ryan SJ, Ed. Retina, Vol. 2: Medical
Retina. St. Louis, MO: CV Mosby, 2005.
126. Seddon JM, Hankinson S, Speizer F, Willett WC. A prospective study
of cigarette smoking and age-related macular degeneration in women.
JAMA 276:1141–1146, 1996.
127. Tomany SC, Wang JJ, van Leeuwen R, Klein R, Mitchell P,
Vingerling JR, Klein BE, Smith W, De Jong PT. Risk factors for
incident age-related macular degeneration: pooled ﬁndings from 3
continents. Ophthalmology 11:1280–1287, 2004.
128. The health consequences of smoking: a report of the Surgeon General,
index.htm. Accessed April 18, 2007.
129. Seddon JM, Rosner B, Sperduto RD, Yannuzzi L, Haller JA, Blair
NP, Willett W. Dietary fat and risk for advanced age-related macular
degeneration. Arch Ophthalmol 119:1191–1199, 2001.
130. Seddon JM, Cote J, Rosner B. Progression of age-related macular
degeneration: association with dietary fat, transunsaturated fat, nuts,
and ﬁsh intake. Arch Ophthalmol 121:1728–1737, 2003.
131. Cho E, Hung S, Willett W, Rimm EB, Seddon JM, Colditz GA,
Hankinson SE. Prospective study of dietary fat and the risk of age-
related macular degeneration. Am J Clin Nutr 73:209–218, 2001.
132. Smith W, Mitchell P, Leeder SR. Dietary fat and ﬁsh intake and age-
related maculopathy. Arch Ophthalmol 118:401–404, 2000.
133. Seddon J, Ajani U, Sperduto R. Dietary fat intake and age-related
macular degeneration (ARVO abstract). Invest Ophthalmol Vis Sci
134. Seddon JM, George S, Rosner B. Cigarette smoking, ﬁsh consump-
tion, omega-3 fatty acid intake, and associations with age-related
macular degeneration. The US Twin Study of age-related macular
degeneration. Arch Ophthalmol 124:995–1001, 2006.