Fish is a rich source of omega-3 fatty acids like EPA and DHA which have important health benefits. Our bodies cannot produce omega-3s and we must obtain them from our diet. EPA and DHA from fish oil help prevent heart disease and inflammation. They are incorporated into anti-inflammatory compounds called eicosanoids. Concentrates of EPA and DHA are produced using methods like urea complexing to separate them from fish oil.

1. Fish oil and human health
Fish is a richest source of HUFAs
Fish is a richest source of two essential fatty acids like α- linolenic
acid (ALA) and linoleic acid
α- linolenic acid is an ω – 3 fatty acid whereas linoleic acid is an ω –
6 fatty acid
Fish is also a richest source of two pharmaceutically important ω –
3 fatty acids like EPA and DHA
Our bodies make most of the fat they need from the carbon,
hydrogen, and oxygen atoms that are found in food. But they don’t
have any way to create omega-3’s and another type of fatty acids,
omega-6’s. Both of these belong to a category called essential fats,
and they come only from certain foods.

2.  Our body can synthesize EPA and DHA from the precursor ALA but at
a very reduced rate (< 5% of the total requirement)
 Moreover elongation and desaturation of ALA is also affected by
competition from common dietary linoleic acid
 Performed dietary EPA and DHA are far more potent than dietary ALA
in changing the proportions of ω-3 fatty acids in platelets and plasma
phosphoglycerides
 That is why EPA and DHA has to be provided through diet
 Human body can synthesize AA provided linoleic acid is available as a
substrate but the human system cannot synthesize linoleic acid
 Human body cannot synthesize ALA. Also both linoleic acid and ALA are
not interconvertible
 Thus our diet should contain both linoleic acid and ALA

3. CORONARY HEART DISEASES (CHD)
Three separate phenomena associated with CHD
 Atherosclerosis
 Thrombosis, and
 Vascular spasm
Atherosclerosis: Thickening of internal wall of blood vessels by
deposition of fatty substances including cholesterol

4. Thrombosis: Formation of aggregate of blood platelets and
associated materials to block the flow of blood through the
restricted atherosclerotic coronary. More acute event.
Vascular spasm: It is an acute event which can rapidly constrict
the blood vessel and cause death of patient with localized death of
tissue
For atherosclerosis (particularly for premature CHD) responsible
factors are elevated levels of total cholesterol, LDL and serum
triglycerides (hyperlipidaemia)
On the other hand HDL is the scavanger of cholesterol and is
inversely related with the atherosclerosis and CHD

5. The body uses both types of omegas to create a variety of short-lived,
hormone like substances called eicosanoids. These substances perform
many functions, such as regulating blood pressure, controlling important
aspects of the reproductive cycle, and inducing blood clotting, among
other things.
Omega – 3 fatty acids help preventing heart disease, angina, high blood
pressure, high cholesterol, asthma, breast cancer, colon cancer, lupus,
multiple sclerosis, rheumatoid arthritis, gout, migraines, prostate
problems, and inflammation.

6. Arachidonic acid, a PUFA of ω – 6 family synthesizes five classes of
metabolites which are collectively known as eicosanoids or
autocoids
These are:
Prostaglandins
Prostacyclin (PGI)
Thromboxane (TXA)
Leukotriene (LTa, LTB, LTC, LTD)
Hydroxyeicosatetraenoic acid (HETE)
 EPA also produces above classes of eicosanoids but these differ
from the metabolites of AMINO ACIDS
 EPE mediates physiological processes by modifying the types and
amounts of eicosanoids that are produced
 Eicosanoids are the most potent biologically active substances yet
discovered

7.  Prostacycline (PGI2) produced from AA or from linoleic acid induces
dilation of blood vessels, is a most potent normal endogenous
inhibitor of platelet aggregation and thus tend to prevent thrombus
formation in blood vessels (i.e. thrombosis)
 Prostacycline (PGI3 ) produced from EPA or from ALA via EPA is similar
to PGI2 in its physiological activities and does not inhibit or reduce the
conversion of AA to PGI2
 Thromboxane (TXA2 ) produced from AA has strong platelet
aggregation (thrombus forming) property and is a vasoconstrictor
 Whereas, thromboxane (TXA3) produced from EPA or from ALA has a
very weak platelet aggregation property and is not thrombotic
 Leukotriene B4 ( LTB4) is a potent inflammatory compound and EPA &
DHA results reduced generation of LTB4 and thus causes the
suppression of inflammatory response

8.  Leukotriene B2 , produced by AA is responsible to intensify conditions
associated with asthma. Dietary n-3 fatty acids reduces the synthesis
of the above metabolite from AA , and thus incidence of intensity of
asthma
 Fish oil (with EPA and DHA) finds a possible use in the treatment of
psoriasis ( a kind of skin disease)
 Various studies have tested fish-oil treatments for the symptoms of
rheumatoid arthritis, the kind of joint-attacking arthritis that can
begin as early as childhood. Analyzing data from the 10 best-
conducted trials to date, researchers concluded that taking fish-oil
supplements for at least three months resulted in modest but
positive improvements, mainly less morning stiffness and tender
joints.
 Animal studies in various tumor models in general indicate that fish
oil (ω-3 PUFA) has antitumor effect and vegetable oils (ω-6 PUFA)
potentiate the tumorigenic effect
 Prostacyclin (PGI2) produced ω-6 PUFA is tumor promoting while ω-3
PUFA reduces its production and concomitantly the growth of certain
tumors

9.  Lack of omega-3 in pregnant mothers increases baby’s risk of impaired
verbal, social and motor skill development
 When pregnant mothers take omega-3 supplements, it has shown to
increase the mental abilities of their babies.
 Poor outcomes associated with insufficient intakes of omega-3 fatty
acids during pregnancy include intrauterine growth retardation, adverse
neurodevelopmental measures, residual deficits in fine motor skills, speed
of information processing in infants, and irreversible deficits in serotonin
and dopamine release
 Amongst PUFA, DHA is involved in neural and retinal development
 A diet inbalanced in ω – 3 / ω – 6 fatty acids can be quite damaging to
the PUFA composition of developing human central nervous system
 Special attention is required to ensure the presence of DHA in all
formulas devised for infant nutrition

10. Production of EPA and DHA concentrates
 Hull and Grimsby Ltd. of UK in 1960 marketed a product called “Ethive”
with 26% EPA and 22% DHA, prepared from cod liver oil
 At present many leading pharmaceutical concerns of the world are
manufacturing and marketing EPA and DHA concentrates in capsule
form
 With a nominal concentration of one EPA or one DHA per triglyceride
molecule , enrichment of triglycerides without interesterification or
resynthesis is not practical beyond 300 mg/g (180 mg EPA and 120 mg
DHA)
 A concentrate with more than 300 mg/g of EPA and DHA is possible by
urea complexing of ethyl esters of fatty acids

11. Separation of PUFA (Urea complexing method)
 To extract and purify polyunsaturated fatty acids, particularly EPA and DHA,
without cis-trans conversion, from naturally occurring oils, such as marine
animal oil and various vegetable oils a mixture of free fatty acids is first
extracted from the oil.
 The resulting mixture of pure fatty acids is then subjected to separation by
means of urea complexing to remove saturated fatty acids and most mono-
unsaturated fatty acids.
 Remaining solvent and urea are then removed from the filtrate which is then
subjected to low temperature fractional crystallization in the presence of an
organic solvent such as acetone.
 Substantially pure polyunsaturated fatty acids, especially EPA and DHA, can
be separately precipitated by reducing the temperature of the filtrate in two
steps.
 Alternatively, the volume of the filtrate is reduced in two steps and cooled to
form precipitates, which are removed. The final product is a mixture of
substantially pure DHA and EPA.

13. A method for separating a substantially pure mixture of (all-Z)-5,8,11,14,17-
eicosapentaenoic acid (EPA) and (all-Z)-4,7,10,13,16,19-docosahexaenoic acid
(DHA) from marine animal oil, using only reaction conditions sufficiently mild to
avoid degradation of the EPA and DHA, consisting essentially of the steps of:
(1) extracting a mixture of polyunsaturated free fatty acids, or methyl or ethyl
esters thereof from the oil,
(2) mixing said fatty acids or esters with urea and a polar organic solvent, the
solvent being present in a quantity sufficient to dissolve the urea and the fatty
acids or esters, and the urea being present in a quantity sufficient to form a
coordination complex with all of the fatty acids or esters capable of being
complexed by the urea;
(3) removing the precipitate which forms after said mixing step and recovering the
filtrate;
(4) removing remaining solvent and urea from the filtrate to obtain pure fatty acids
or esters;
(5) forming a solution by dissolving the pure fatty acids or esters in an organic
solvent;

14. (6) gradually cooling the solution until a first precipitate forms and removing said
first precipitate;
(7) removing sufficient solvent from the filtrate remaining after the precipitate is
removed to substantially reduce the volume and increase the concentration of the
solution;
(8) gradually cooling the solution until a second precipitate forms and removing
said second precipitate;
(9) removing sufficient solvent from the filtrate remaining after the second
precipitate is removed to substantially reduce the volume and increase the
concentration of the solution;
(10) gradually cooling the filtrate until a separate liquid or solid phase forms and
removing said separate phase; and
(11) retaining the remaining liquid phase containing a mixture of substantially
pure EPA and DHA.

15. Packing of EPA and DHA concentrate
To protect the oil or concentrate against oxidation and to retard off
flavour formation, it is indispensable to stabilize by
Using permitted antioxidants (quite often tocopherol is used as
antioxidant
Storage under nitrogen at low temperature
Protection from light
Soft gelatin capsule is an ideal and stable container for fish oil or EPA
and DHA concentrate in small amounts required for human consumption

16. Omega – 3 fatty acids also control or prevent the following conditions
Control of body weight
Osteoporosis
Cholesterol level and high blood pressure
Mental depression
Pre-term labour
glaucoma

17. According to general recommendations on dietary fats for human
consumption, the diet should supply 0.8 g EPA and DHA per day
(0.27% calories)
With a fatty species like oil sardine (S. longiceps), 100 g serving may
provide about 3.2 g of EPA and DHA but for white pomfret
(Stromateus cinensis) of India, it may be as low as 0.083 g .
Regular intake of fish oil or EPA and DHA concentrate in the form of
capsule may ensure a regular supply of omega – 3 fatty acid
requirements of our system

18. Good food sources of omega – 3 fatty acids
Mackerel, salmon, herring, bluefish, albacore tuna, rainbow trout, and
swordfish
Cautions and possible side effects
Increases bleeding time, possibly resulting in nosebleeds and easy
bruising, and may cause upset stomach. Do not take if you have a
bleeding disorder or uncontrolled high blood pressure, take
anticoagulants (blood thinners) or use aspirin regularly, or are allergic to
any kind of fish. Take fish oil, not fish-liver oil, which is high in vitamins A
and D—vitamins that may be toxic in high amounts. People with diabetes
should not take fish oil because of its high fat content.