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 body.
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, hemp, Camelina) 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 to perform 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 to health.
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 died.
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
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 time.
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
- 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 Association guidelines.
- 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
- 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 by researchers.
- 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 system.
- 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
- 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 to prostaglandins):
"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.
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, please click
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 (blood
of blood vessels)
|| Vasoconstriction (narrowing of vessels)
| Anti-inflammatory effect
|Immune system enhancement
||Immune system suppression
|Increased oxygen flow
||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
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
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)
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
* 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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