Fatty Acids and Health: an Overview
Definition of omega-3 fatty acids
Omega-3 fatty acids are long-chain polyunsaturated
fatty acids (18-22 carbon atoms in chain length) with the
first of double bonds beginning with the third carbon atom.
They are called “polyunsaturated” because their molecules
have two or more of the so-called “double bonds” between carbon
atoms. Their designation as “long-chain” fatty acids has to
do with the fact that they consist of at least 18 carbon atoms.
The picture below illustrates the molecular
structure of alpha-linolenic acid (ALA, omega-3 family) as
compared to linoleic acid (LA, omega-6 family). Both of them
consist of 18 carbon atoms and are classified as polyunsaturated,
but ALA has three double bonds, the first of which is located
in the third position from the “end” of the molecule, whereas
LA has just two double bonds, starting with the sixth position.
These differences may seem very minor, but they are of paramount
importance in terms of the physiological action of ALA and
LA, making them perform totally different roles in the human
The omega-3 family of fatty acids includes alpha-linolenic
acid (ALA, 18 carbon atoms, 3 double bonds), eicosapentaenoic
acid (EPA, 20 carbon atoms, 5 double bonds), and docosahexaenoic
acid (DHA, 22 carbon atoms, 6 double bonds). ALA is the "base"
omega-3 fatty acid, from which EPA and DHA are made in the
body through a series of enzymatic reactions called "elongation"
(the molecule becomes longer by incorporating new carbon atoms)
and "desaturation" (new double bonds are created). In nature,
ALA is primarily found in certain plant seeds (e.g., flax,
and their oils, and in most green leafy vegetables (especially
purslane), whereas EPA and DHA mostly occur in the tissues
of cold-water fish (such as salmon, sardines, and mackerel),
and in some marine plants.
Omega-3s are not just "good fats". They
are truly essential for health and vitality
After the advent of the so-called "lipid hypothesis",
which linked the consumption of dietary fat with increased
risk of heart disease and other health problems, fats were
so heavily demonized by the official medical establishment
that many people started thinking that the best answer to
the "fat problem" is to stay away from it altogether. Big
food processing companies were quick to realize the enormous
profit potential of this trend, and soon the market became
flooded with "low fat" and "fat-free" products, promising
to put an end to obesity and heart disease.
However, not all fats were created equal. While
the consumption of some types of fat may, indeed, be a risk
factor for certain health problems (synthetic trans-fats,
so dearly loved by the food-processing industry, rather than
natural fats, seem to be the primary culprit here), some other
fats, including alpha-liniolenic acid (ALA) from the omega-3
family, are so important for health that they have been termed
"essential fatty acids" (EFAs). The essential nature of these
fatty acids stems from the fact that our bodies need them
vitally important functions, but are unable to manufacture
them. Therefore, we must get them from outside sources (such
as food or dietary supplements). That's why any attempt to
indiscriminately reduce or eliminate all fats from one's diet
inevitably leads to an EFA deficit, which may be very detrimental
Essential fatty acids were first discovered
back in 1929 by a husband-and-wife research team George and
Mildred Burr. While doing animal research, they have noticed
that a lack of essential fatty acids caused the animals to
develop some serious health problems, including scaling and
swelling of the skin, as well as damage to internal organs.
If the EFA deficit was left unattended, the animals eventually
In 1956, Hugh Sinclair, one of the world's
greatest researchers in the field of human nutrition, has
suggested that an upsurge in the so-called "diseases of civilization"
- namely, coronary heart disease, thrombosis, strokes, diabetes,
chronic inflammation, and cancer - was caused by abnormalities
in fat metabolism. According to his writings, the main reason
for such abnormalities was the fact that modern-day diets
are full of processed foods rich in trans-fatty acids, while
being extremely poor in essential fatty acids. According to
Hugh Sinclair, this EFA deficit was the main reason behind
his striking observation: in spite of improvements in medicine
and standard of living, the life expectancy of a 50-year-old
man had not changed since the middle of the 19th century.
Although Sinclair's opinions were not supported
by his peers at the time, and he was even ridiculed by some
of them for his bold hypothesis, later research has convincingly
shown that he was, indeed, correct. In fact, he is now universally
recognized and praised for insights that were far ahead of his
role of omega-3 EFA in disease prevention and treatment
During the 50 years that have elapsed after
Hugh Sinclair's discoveries, EFAs, including omega-3 fatty
acids, have been extensively researched by scientists. This
research has brought some extremely interesting and promising
results in terms of the potential of omega-3 fatty acids to
prevent and treat many modern diseases. It has been shown
that ensuring the presence of an adequate amount of omega-3s
in the diet may help to achieve the following health-promoting
- Anti-clotting (thrombolytic) effect:
Omega-3s help to avoid thrombosis (formation of blood clots)
by preventing platelets (thrombocytes) from sticking together
and forming blood clots. Blood clots, which may result in
stroke, heart attack, or pulmonary embolism (PE), are the
#1 cause of death in thw Western world, but most of them
are preventable by including omega-3 fatty acids and other
anti-clotting foods and supplements into one's diet.
- Lowering the risk of heart disease, including
CHD (coronary heart disease) and atherosclerosis. Omega-3
fatty acids have been proven in many clinical studies to
benefit heart health, particularly through their vasodilatory
(widening of blood vessels) and anti-atherogenic (preventing
the formation of artery-blocking atherosclerotic plaques)
effects. These findings are supported by the American Heart
- Lowering the level of triglycerides
(fats) in the blood. The effectiveness of omega-3s
in lowering blood triglycerides (fats) known to be a risk
factor for cardiovascular disease has been well established
in multiple clinical studies.
- Lowering high blood pressure (alleviating
hypertension). Omega-3 fatty acids have been shown
to lower mild hypertension when it is due to cardiovascular
disease, specifically atherosclerosis (hardening of the
artery walls, formation of arterial plaques, and the resulting
narrowing of the arteries).
- Reduction in heart irregularities.
Omega-3 EFAs have been shown to lower heartbeat rates and
prevent arrhythmias (disturbances of the normal rhythm in
the heart's beating), thus decreasing the chances of a sudden
death from a heart attack.
- Alleviation of circulatory problems.
Circulatory problems such as varicose veins and Raynaud's
disease benefit from omega-3 supplementation. Omega-3s stimulate
blood circulation and increase the breakdown of fibrin,
a compound involved in clot and scar formation.
- Helping to alleviate mood disorders,
such as depression. Persons with mood disorders
may also benefit from omega-3 supplementation.
Lack of omega-3 fatty acids has been linked to depression
- Reducing aggression. A
new study of teenagers has found that the consumption of
omega-3 EFAs relates to lower hostility rates in teenagers.
Hostility has been shown to play a role in the development
and manifestation of heart disease.
- Helping patients with attention
deficit/hyperactivity disorder (ADHD), dyslexia and dyspraxia.
As is the case with depression and other mood disorders,
persons who suffer from ADHD, dyslexia and dyspraxia (absence
of ability to perform coordinated skilled movements) benefit
from omega-3 supplementation.
- Helping to improve memory and learning
skills, and prevent Alzheimer's disease. Studies
have proven that omega-3 fatty acids improve brain function
and that the intake of omega-3s is linked to a lowered risk
of developing Alzheimer's disease. Studies also suggest
that omega-3 EFAs may have a protective effect on the nervous
- Prevention of allergies in children.
Studies have demonstrated that omega-3 fatty acid intake
by prospective mothers during pregnancy may protect their
babies against the development of allergies. Omega-3s have
been found to protect against symptoms of hay fever, sinus
infections, asthma, food allergies, as well as allergic
skin conditions such as hives and eczema.
- Improving the condition of those
who suffer from inflammatory skin disorders such as psoriasis
and eczema. In the skin of persons with psoriasis
and other inflammatory skin disorders the amount of compounds
causing inflammation is many times greater than normal.
Omega-3 EFAs inhibit the production of these inflammatory
compounds, improving the health of skin, nails and hair.
- Alleviating rheumatoid arthritis
(RA) and other inflammatory forms of arthritis, affecting,
in particular, persons with psoriasis and gout.
Omega-3 fatty acids reduce the amount of compounds causing
inflammation, and increase the formation of anti-inflammatory
substances such as PGE3.
- Improving the immune status.
The intake of omega-3 fatty acids has been proven to be
beneficial for the body's immune function. Research has
also linked the intake of omega-3s to lowered risk of breast
cancer and prostate cancer.
- Alleviating certain symptoms of
PMS. Premenstrual symptoms such as pain, cramps
and bloating are often alleviated by resorting to omega-3
supplementation. Omega-3 fatty acids are converted into
hormone-like substances (type 3 prostaglandins, or PGE3),
which help to control contractions of the uterus.
- Improvement of visual acuity.
Research has shown that consumption of omega-3 EFAs is linked
to lowered risk of age-related macular degeneration - an
eye condition which is the leading cause of severe loss
of vision in people over 50.
omega-3s work: an introduction to prostaglandins
It is obvious that an adequate daily
intake of omega-3 fatty acids can play a vital role in the
prevention and treatment of a great number of serious and
widespread diseases affecting modern societies. The ability
of omega-3s to achieve these health-promoting effects is primarily
due to their role as the precursors of prostaglandins - localized
tissue hormones that seem to be the fundamental regulating
molecules in most forms of life. They do not travel in the
blood like hormones, but are created in the cells to serve
as catalysts for a large number of processes including the
movement of calcium and other substances into and out of cells,
dilation and contraction, inhibition and promotion of clotting,
regulation of secretions, including digestive juices and hormones,
and control of fertility, cell division and growth. This unique
significance of omega-3s and prostaglandins for major life-supporting
processes in the human body led Dr. Mary Enig, a leading lipid
researcher and nutritional scientist of our times, and Ms.
Sally Fallon, President of Weston
A. Price Foundation, to making the following statement:
"Research into prostaglandins holds enormous
promise for the treatment of disease with various drugs that
selectively inhibit or stimulate the production of specific
prostaglandins. Such drugs might be likened to police officers
used to direct traffic or called on to help at the scene of
an accident. For most of us, however, the best way to ensure
adequate prostaglandin production along with proper balance
between the various series and their subsets is to follow
a diet that provides precursors to eicosanoid production,
and keeps the pathways free from blocks and potholes, a diet
that provides fuel for our prostaglandin cars and keeps the
highways clear." (Tripping Lightly down the Prostaglandin
Pathways, Sally Fallon and Mary Enig, PhD, 1996).
In the same article, the authors go on
to explain the specific mechanisms behind the formation and
major actions of EFA-derived prostaglandins and other eicosanoids
(20-carbon hormone-like tissue substances which are similar
"Prostaglandins are produced in the cells
by the action of enzymes on essential fatty acids. There are
two prostaglandin pathways, one that begins with double-unsaturated
omega-6 linoleic acid and one that begins with triple-unsaturated
omega-3 alpha-linolenic acid. Both pathways essentially involve
elongation of the 18-carbon EFA's to the 20-carbon root used
in each of the three eicosanoid types, plus further desaturation.
the omega-6 pathway, the Series 1 prostaglandins are produced
from a 20-carbon, triple unsaturated fatty acid called dihomo-y-linolenic
acid (DGLA) that is found in liver and other organ meats.
The Series 2 prostaglandins are produced from a 20-carbon
quadruple unsaturated fatty acid called arachidonic acid (AA)
found in butter, animal fats, especially pork, organ meats,
eggs and seaweed.On the omega-3 pathway, the Series 3 prostaglandins
are produced from a 20-carbon quintuple unsaturated fatty
acid called eicosapentaenoic acid (EPA)...". For a detailed
diagram describing the omega-3 and omega-6 prostaglandin pathways,
A fundamental shift in the omega-6/omega-3
ratio created a major prostaglandin imbalance, giving rise
to "diseases of modern civilization"
"Early research focused on the interplay
between the Series 1 and Series 2 prostaglandins. In the most
simple terms, the Series 2 prostaglandins seem to be involved
in swelling, inflammation, clotting and dilation, while those
of the Series 1 group have the opposite effect. This has led
some writers, notably Barry Sears in his popular book The
Zone, to call the Series 2 family the "bad" eicosanoids and
to warn readers against eating liver and butter, sources of
arachidonic acid, the Series 2 precursor. Sears also asserts
that perfect balance of the various prostaglandin series can
be achieved by following a diet in which protein, carbohydrate
and fat are maintained in certain strict proportions. This
is a highly simplistic view of the complex interactions on
the prostaglandin pathway, one which does not take into account
individual requirements for macro and micro nutrients, nor
of imbalances that may be caused by nutritional deficiencies,
environmental stress or genetic defects. Like all systems
in the body, the many eicosanoids work together in an array
of loops and feedback mechanisms of infinite complexity...
The Series 2 prostaglandins do indeed
play a role in swelling and inflammation at sites of injury.
This is not at all a "bad" effect, but an important protective
mechanism - the body's way of immobilizing the affected site
to prevent further injury and facilitate healing. Series 2
prostaglandins also seem to play a role in inducing birth,
in regulating temperature, in lowering blood pressure, and
in the regulation of platelet aggregation and clotting.
Later investigators have focused on the
balance between Series 2 and Series 3 prostaglandins. The
Series 2 group is involved in intense actions, often in response
to some emergency such as injury or stress; the Series 3 group
has a modulating effect. Series 2 eicosanoids might be likened
to the "fast lane" in that they are often associated "with
an explosive, but transient burst of synthesis. . . if the
rate of synthesis is too slow, there will be insufficient
active eicosanoids to occupy receptors. If the rate is synthesis
is too fast, excess active eicosanoids can cause pathophysiology."
The Series 3 prostaglandins are formed at a slower rate and
work to attenuate excessive Series 2 production. Their response
is "less vigorous". The omega-3 pathway might therefore be
likened to the "slow lane." Adequate production of the Series
3 prostaglandins seems to protect against heart attack and
stroke as well as certain inflammatory diseases like arthritis,
lupus and asthma." (Op. Cit.)
The table below illustrates the opposing
effects of different-series prostaglandins on human physiology:
Series 3 Prostaglandins (omega-3)
2 Prostaglandins (omega-6)
platelet aggregation (blood clotting)
|Increased platelet aggregation
of blood vessels)
|| Vasoconstriction (narrowing
|Immune system enhancement
||Immune system suppression
||Decreased oxygen flow
|Decreased cell proliferation
||Increased cell proliferation
|Widening of respiratory
||Narrowing of respiratory passages
|| Lowered endurance
Therefore, for the complex system of essential
fat metabolism to function properly, the maximum allowable daily
intake of omega-6 fatty acids should be no more than four times
greater than the corresponding omega-3 intake. If the intake
of omega-6 fats exceeds this maximum allowable level, the body
starts producing too many series 2 (omega-6) prostaglandins,
and too few series 3 (omega-3) prostaglandins, causing the delicate
system of metabolic “checks and balances” to malfunction. Hugh
Sinclair was right: the advent of processed foods abundant in
“bad fats” (trans-fatty acids and excessive omega-6 linoleic
acid) and deficient in “good fats” (omega-3 fatty acids) caused
a fundamental abnormality in fat metabolism. The omega-6/omega-3
ratio went completely out of control. In fact, the current average
omega-6/omega-3 ratio in the American diet is not 2:1 or even
4:1, but a whopping 20:1 (!).
It may, indeed, seem from this table that the effects of series
3 prostaglandins derived from omega-3 fatty acids (PGE3)
are mostly “positive”, making them “good prostaglandins”,
whereas series 2 prostaglandins derived from omega-6s (PGE2)
are “bad prostaglandins”. However, as was explained above,
this view is too simplistic. The fact is that both groups
of prostaglandins perform vitally important functions and
supplement each other through complex and multi-faceted interactions.
There is only one crucial condition that must be fulfilled
if the entire system is to work well and promote health, rather
than disease. This condition is BALANCE. For the prostaglandin
pathways to run smoothly, the intake of omega-3 and omega-6
fatty acids must be well-balanced, as was the case during
99% of human history – before the global switch to industrial
agriculture and processed foods. For many centuries, the ratio
between omega-6s and omega-3s was within the 1:1 to 4:1 range
believed by most scientists to be acceptable for optimal metabolism
of fats and proportionate production of different prostaglandins.
This means that the effects of omega-6-derived prostaglandins,
which are beneficial under certain circumstances but can be
harmful if the system goes out of balance, begin to overwhelm
the body and cause serious health problems. Their thrombogenic
(blood-clotting), pro-inflammatory action, when not attenuated
by thrombolytic (blood-thinning and anti-clotting), anti-inflammatory
properties of omega-3 prostaglandins, leads to the formation
of potentially dangerous blood clots and throws the body into
the state of chronic inflammation, giving rise to a whole array
of clot- and inflammation-related chronic diseases, including
thrombosis, arthritis, diabetes, and asthma. The tendency of
PGE2 to narrow
the blood vessels and promote blood platelet aggregation is
conducive to atherosclerosis and coronary heart disease (CHD).
In addition, their ability to stimulate cell proliferation may
play a role in the development of malignant tumors.
How much omega-3 EFAs do we
need and what are the best sources of omega-3s?
Apparently, by adding a certain amount
of omega-3 EFAs to the diet it is possible to restore the
vitally important prostaglandin balance, avoiding or reversing
the negative health consequences of the omega-6 overload.
The are two questions that must be answered here: 1) what
should be our daily intake of omega-3 fatty acids; and 2)
what are the best sources of dietary omega-3s.
Scientists have not yet developed a universal answer with
regard to how much omega-3 EFAs are needed daily. Perhaps
the most detailed and authoritative recommendations in this
regard were made by the participants of the Workshop on the
Essentiality of and Recommended Dietary Intakes for Omega-6
and Omega-3 Fatty Acids, held in Bethesda, Maryland, under
the auspices of the International Society for the Study of
Fatty Acids and Lipids (ISSFAL).
The Workshop participants consisted of investigators of the
role of essential fatty acids in nutrition, cardiovascular
disease, and mental health. It was truly international in
nature bringing together scientists from academia, government,
international organizations, and industry from Australia,
Canada, Denmark, France, Italy, Japan, Norway, Switzerland,
United Kingdom, and the United States.
The Workshop participants came to the following conclusion:
“After much discussion consensus was reached on the importance
of reducing the omega-6 polyunsaturated fatty acids (PUFAs)
even as the omega-3 PUFAs are increased in the diet of adults
and newborns for optimal brain and cardiovascular health and
function. This is necessary to reduce adverse effects of excesses
of arachidonic acid (AA) and its eicosanoid products. Such
excesses can occur when too much linoleic acid (LA) and AA
are present in the diet and an adequate supply of dietary
omega-3 fatty acids is not available. The adverse effects
of too much arachidonic acid and its eicosanoids can be avoided
by two interdependent dietary changes. First, the amount of
plant oils rich in LA, the parent compound of the omega-6
class, which is converted to AA, needs to be reduced. Second,
simultaneously the omega-3 PUFAs need to be increased in the
diet. LA can be converted to arachidonic acid and the enzyme,
delta-6 desaturase, necessary to desaturate it, is the same
one necessary to desaturate alpha-linolenic acid (ALA), the
parent compound of the omega-3 class; each competes with the
other for this desaturase. The presence of ALA in the diet
can inhibit the conversion of the large amounts of LA in the
diets of Western industrialized countries which contain too
much dietary plant oils rich in omega-6 PUFAs (e.g. corn,
safflower, and soybean oils). The increase of ALA, together
with EPA and DHA, and reduction of vegetable oils with high
LA content, are necessary to achieve a healthier diet in these
countries.” (Artemis P. Simopoulos, MD, The Center for
Genetics, Nutrition and Health, Washington, DC, U.S.A.; Alexander
Leaf, MD, Massachusetts General Hospital, Charlestown, MA,
U.S.A.; Norman Salem, Jr. PhD, National Institute of Alcohol
Abuse and Alcoholism, National Institutes of Health, Rockville,
MD, U.S.A. Final Statement by the Participants of the Workshop
on the Essentiality of and Recommended Dietary Intakes for
Omega-6 and Omega-3 Fatty Acids. Bethesda, MD 1999)
regard to the recommended dosages of omega-6 and omega-3 fatty
acids, the Workshop agreed upon the following guidelines:
1) for linoleic acid (LA), an adequate intake
(AI)* was set at 4.44 grams per day, with an upper limit
of 6.67 grams per day (2% and 3% of daily caloric intake,
respectively, based on a 2000-calorie diet);
2) for alpha-linolenic acid (ALA), an adequate
intake (AI)* was set at 2.22 grams per day (1% of daily
caloric intake), with no upper limit.
Therefore, based on the recommendations of
the Workshop, we need at least 2.22 grams of ALA per day.
This translates into approximately one teaspoon
(5 ml) of flax oil or its more stable and better-tasting counterpart
- Camelina (wild flax)
oil - daily. However, it is important to realize that
it is very difficult not to exceed the upper limit for LA
consumption (6.67 grams daily) unless you make a consistent
effort to replace processed foods with natural, healthier
alternatives present in traditional
diets. For example, just one serving of corn, soybean
or almost any other "supermarket" vegetable oil supplies 7-8
grams of LA, exceeding the upper daily limit on LA consumption.
Moreover, the major problem with processed foods is that highly
processed (refined, deodorized, or hydrogenated) omega-6 vegetable
oils are one of their “cornerstone” ingredients, sharing this
dubious honor with refined sugar and white flour. As a result,
by eating processed foods we consume sizable amounts of omega-6
linoleic acid without even paying attention to it. For example,
such processed foods as cakes, cookies, crackers, pies, and
bread, as well as potato chips, corn chips, popcorn, and other
popular snacks (as well as many other “supermarket foods”
– there are too many of them to mention here), are usually
loaded with omega-6 fats, often in their most dangerous hydrogenated
(trans-fat) form. If the consumption of such foods is not
curtailed, the daily upper limit for omega-6 fatty acid intake
may easily be exceeded many times over.
Moreover, the rate of enzymatic conversion of
alpha-linolenic acid into longer-chain precursors of prostaglandins
is not uniform, and may be negatively affected by such widespread
factors as aging, vitamin and mineral deficiencies, consumption
of trans-fatty acids and alcohol, low thyroid function, smoking,
and stress. For instance, achieving a maximum rate of ALA-to-EPA
conversion requires an adequate daily intake of vitamins C,
B6, B3, zinc and magnesium, preferably from natural sources,
which are not always available.
With this in mind, in order to ensure an extra
degree of protection against disease-causing abnormalities
in fat metabolism, it may be advisable to increase omega-3
supplementation to a level higher than 2.22 grams of ALA daily,
especially considering that, as opposed to the case with omega-6s,
the experts did not impose an upper limit on omega-3 EFA consumption.
Therefore, many nutritionists recommend a daily dose of one
tablespoon (15 ml) of an ALA-rich oil (such as flax or Camelina oil), supplying about 6 to 8 grams of ALA. This
amount of daily omega-3 supplementation will compensate for
a probable excess of omega-6s in the diet, as well as for
a possibility of an impaired ALA-to-EPA conversion.
For a discussion of the advantages and disadvantages
of different available sources of omega-3 fatty acids, please
visit this page. If you need more
information or have questions, please contact our holistic
nutritionists at email@example.com.
* If sufficient scientific evidence is not
available to calculate an Estimated Average Requirement, a reference
intake called an Adequate Intake (AI) is used instead of a Recommended
Dietary Allowance. The AI is a value based on experimentally
derived intake levels or approximations of observed mean nutrient
intakes by a group (or groups) of healthy people. The AI is
expected to meet or exceed the amount needed to maintain a defined
nutritional state or criterion of adequacy in essentially all
members of a specific healthy population.
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