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Issue 79
Fish Oils and Omega 3 fatty acids
Heart Health
Foetal brain development
Arthritis
Menstrual symptoms
Depression
Osteoporosis
Research
Fish Oils and Omega 3 fatty acids
Fish can be divided into oily and lean groups. Oily or fatty fish store
fats as triacylglycerols in the flesh of the fish; for example salmon, anchovies,
herring, mackerel, pilchards, sardines and trout. Whereas in lean fish such
as cod and halibut, the fats are stored in the liver. When taking fish liver
oils, it is important that vitamin A and vitamin D intake is checked to ensure
that the upper safe levels are not exceeded. This is because the vitamins are
fat-soluble and are not excreted as easily as the water-soluble B vitamins and
vitamin C. When taking cod liver oil, daily intake should not exceed 2500 i.u.
for pregnant women, while other individuals should not exceed 7500i.u
Fish oils are particularly rich in omega 3 fatty acids eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA). These fatty acids are converted by the
body into the beneficial series 3 prostaglandins. The real value of fish oil
is its EPA and DHA content; generally speaking EPA in heart health and DHA in
health and structure of the brain.
Plants are a source of alpha-linolenic acid (ALA), an omega 3 fatty acid that
has the potential to be converted into EPA and DHA. ALA is present in cell membranes
of green leafy vegetables, linseed (flax) oil, soy oil and the seeds of plants.
The consumption of plant leaves from lettuce, cabbage and other green vegetables
provides most of the ALA in the diet. The composition of fatty acids does not
vary much between the different type of leaves (1). However, even if our diet
is very rich in these, we may still be deficient in series 3 prostaglandins
because the enzymes needed to convert ALA into EPA are only weakly active. Essentially
the pathway goes as follows: ALA is converted into stearidonic acid (SA), which
is then turned into eicosatetraenoic acid (ETA). ETA is transformed into EPA
which is then converted to either docosapentaenoic acid (DPA), or prostaglandin
series 3. DPA proceeds to become DHA. Dietary EPA can therefore be extremely
valuable because it skips this step and provides a material from which series
3 prostaglandins can easily be produced.
Heart Health
Fish oils have been found to have significant benefits on heart health, including:
"Altering the balance of blood fats in a favourable way."
"Reducing the likelihood of blood clotting."
"Making the heart less prone to arrhythmias (irregular heartbeats)."
"Reducing the viscosity of the blood, thereby facilitating blood flow."
" Consuming large amounts of fish or taking fish oil capsules can significantly
reduce the risk of cardiac problems. The first study found that men who consumed
the most fish, regardless of age or smoking habits, were 81% less likely to
suffer a cardiac death compared to those who ate little or no fish. Men who
consumed modest amounts of fish had a 72% lower risk of death."
" A study monitored the health of 111,000 patients who had suffered heart
attacks. During the three and a half years of the study, all subjects were encouraged
to follow a Mediterranean style diet and some took a daily 1000mg fish oil supplement
providing EPA and DHA. Subjects taking fish oil capsules were noted to be significantly
less likely to suffer a cardiac related death."
" Fish oil may also help to prevent heart disease by raising beneficial
HDL cholesterol, reducing homocysteine levels and reducing hypertension."
Foetal brain development.
During pregnancy, women are advised to keep up their intake of omega 3 fatty
acids by eating oily fish or taking fish oil supplements if necessary. This
is because more and more research is showing how vitally important omega 3 fatty
acids are for development of the foetal brain .
Arthritis
Prostaglandins are short-lived hormone like substances that have anti-inflammatory
action. Prostaglandin series 3 are derived from omega-3 fatty acids. Improvements
in the symptoms of rheumatoid arthritis have been reported in patients taking
fish oil supplements.
Fish oil therapy is free from side effects and may also enhance the effects
of conventional drugs.
Menstrual symptoms
Regular use of fish oil may be beneficial to women who experience menstrual
cramps.
Depression
Research has found that the omega-3 fatty acids in fish oil may help to suppress
the signals responsible for sudden changes in mood; this may particularly benefit
those who suffer with depression.
Osteoporosis
Essential fatty acids (EFAs) present in fish oil may help treat osteoporosis
when taken with calcium supplements. Studies show that women who take fish oil
with calcium have better bone density and fewer fractures than women who take
calcium alone.
Fish oil has been used in very high amounts in clinical research without any
overt toxicity symptoms. However, when taking high levels of fish oil, patients
should be monitored by a medical professional, because omega 3 fatty acids can
displace omega 6 fatty acids from cell membranes. There may also be a thinning
of the blood and a reduction in clotting time. High dose fish oils should be
avoided by those on blood thinning drugs such as warfarin and heparin.
Research
Fish and Good Health
A diet rich in fresh fruit and vegetables has been shown to protect against
tumour development. Likewise, cutting down on red meats and selected foods may
help to reduce the incidence of certain types of cancers. However, until now,
only a few studies have examined the benefits from regular fish consumption
on cancer risk. American researchers examined the relationship between frequency
of fish consumption and risk of cancer development. To accomplish this, the
researchers used data from a series of integrated case-controlled studies conducted
in northern Italy between 1983 and 1996. From the data, there was a consistent
pattern of protection against the risk of digestive tract cancer where a diet
rich in fish was consumed. The fact that fish is rich in omega-3 fatty acids
may, in part, explain why a diet rich in this food type reduces the risk of
cancer, as these fatty acids have an anti-inflammatory effect and inhibit the
growth of cancers in the body.
Fish Oil and Eye Health
Studies demonstrating regular use of omega-3 fatty acids have noted that EFAs
can offer protection against some degenerative disease in the elderly. A group
of researchers have studied the effects of EFAs on common eye diseases. Regular
intakes of omega-3 in the form of oily fish may have a preventative effect on
cataracts and glaucoma, two of the most common eye diseases leading to blindness.
Fish Oil or Plant-Based Omega 3 Oil?
Omega-3 fatty acids can be derived from both vegetable and fish oils, but recent
research has shown that only the kind from fish have a blood thinning action
in the body. ALA is an omega-3 essential fatty acid obtained predominantly from
vegetable oils such as rapeseed and soya bean oils. In the body, this fatty
acid is converted into a number of beneficial longer chain fatty acids including
EPA and DHA. However, fatty fish such as salmon, sardines and herrings provide
a convenient pre-formed source of these longer chain fatty acids. It is known
that populations consuming a diet rich in oily fish have a lower incidence of
coronary heart disease (CHD). In addition, a number of studies have demonstrated
that omega-3 fatty acids play a pivotal role in maintaining the health of the
heart. Despite the fact that the average daily intake of ALA is considerably
higher than EPA and DHA, most studies have focused on the health benefits of
the latter. More recently, Dutch scientists have compared the blood-thinning
effects of ALA with those of EPA and DHA in elderly subjects. In addition, the
blood thinning effect of ALA was compared with the observed effect in younger
volunteers. This enabled scientists to assess whether the conversion of ALA
into EPA and DHA is affected by age. The results showed that EPA and DHA from
fish oil reduced blood platelet aggregation. No such benefits were seen in those
consuming ALA. In addition, the effects of ALA were not age-related. In conclusion,
this study demonstrates the importance of obtaining omega-3 fatty acids from
fish rather than relying on vegetable sources. As the British consumption of
fish falls well short of the recommended 1-3 portions of oil-rich fish per week,
fish oil supplements provide a reliable and convenient source.
Quality rather than Quantity
A good mix of essential fatty acids from fish, plants, nuts and seeds is of
great benefit to human health. It is more important to have quality fats from
polyunsaturates and monounsaturates in unprocessed foods, than to have quantity
of fats from saturated, hydrogenated or trans-fatty acids in processed, refined
foods.
Making the most of omega-3s
As with all essential fatty acids, absorption of omega 3s is affected by excessive
amounts of alcohol, sugar, medication, stress and lack of particular vitamins
and minerals. A healthy diet and lifestyle will provide the correct environment
for the absorption and metabolism of omega 3s. A multinutrient food supplement
will provide necessary nutrients and would be a useful adjunct to the diet,
while a twenty minute daily walk at lunchtime will benefit the cardiovascular
system and the metabolism.
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