Omega-6
GLA對健康獲益良多
Health Benefits of Omega-6 GLA
Evening primrose oil (EPO) is extracted from the seeds of
Oenothera biennis L., a plant which originates from North
America. It gained the name primrose because of its vibrant
yellow flowers, often associated with the primrose. In addition,
its brightly-coloured petals open in the evening - hence the
commonly recognised name of Evening Primrose.
During the 17th century evening primroses were introduced
into Europe and the plant soon became known as the King"s
Cure All because of its medicinal properties. It was more
than two centuries, however, before official studies on EPO
began. In 1919, it was discovered in Germany that EPO contains
gamma linolenic acid (GLA - an omega-6 fatty acid). This was
the beginnings of a large body of research, which continues
to this day, into the health benefits of GLA. Possibly the
most impressive findings relate to cholesterol and cell generation,
although its recently-discovered potential to inhibit breast
cancer cells is equally notable.
GLA is essential for maintaining the permeable structure
of cell membranes. This is vital for effective cell signalling
in the body and brain as it ensures cells are able to obtain
the nutrients needed to function properly. The body also converts
GLA into prostaglandins - hormone-like substances that control
the regulation of inflammation, pain, blood pressure, fluid
balance and blood-clotting.
There are many health benefits associated with EPO, particularly
its virgin form, which is a rich source of triterpenes:
Virgin EPO, as in omega product, is rich in GLA, which moisturises
the skin from within, protecting it from environmental,
oxidative damage. Eczema may arise from problems
converting dietary fats into GLA. EPO relieves eczema-related
inflammation of the skin, as well as the ancillary symptoms
of itching, scaling, oozing and redness - for these reasons,
it may also relieve Psoriasis.
It is beneficial for the hair and nails. The rich supply of
GLA in virgin EPO helps to keep nails in optimum condition
by preventing them from chipping or breaking. This essential
fatty acid also nourishes the scalp.
GLA is recommended by the NHS to help those who suffer from
cyclical breast pain associated with menstruation.
GLA is also converted into prostaglandins and leukotrienes,
which regulate inflammation and pain and therefore may ease
period pains. In addition triterpenes may
boost the immune system and could help women who feel rundown
during menstruation.
Evening primrose oil reduces the joint pain and
swelling associated with arthritis. In a
randomised, placebo-controlled trial by Zurier et. al., treatment
with GLA for six months resulted in "statistically significant
and clinically relevant reductions in the signs and symptoms
of disease activity in patients with RA [rheumatoid arthritis]"[i].
Some researchers believe that GLA is even more effective when
taken with the omega-3 fatty acid, EPA. In Chronic Fatigue
Syndrome - A Natural Way to Treat ME, Professor Puri writes:
"Osteoarthritis and some cases of other types of arthritis
(such as rheumatoid arthritis) are helped by taking a combination
of EPA and virgin evening primrose oil. The EPA helps restore
the functioning of the synovial fluid of the joints, while
a particularly important helpful component of virgin evening
primrose oil is the family of triterpenes (which help relieve
the pain associated with arthritis)."[ii] omega product
combines EPA and GLA, both of which are excellent for maintaining
the health of joints.
GLA may be helpful to those with Alcoholism.
GLA prompts the brain to produce prostaglandin E, which plays
a role in the regulation of the liver. In a clinical trial
by Professor David Horrobin, in the Review of Contemporary
Pharmacotherapy (1990), alcoholics whose diet was supplemented
with evening primrose oil experienced significantly reduced
severity of withdrawal symptoms, as well as improved liver
function[iii].
GLA reduces LDL cholesterol and high blood
pressure. In 1994, a Chilean placebo-controlled clinical
study demonstrated the positive effects of GLA on blood cholesterol[iv].
The study included 12 men with increased levels of LDL cholesterol
and a known family history of premature coronary artery disease.
The patients received 240 mg of GLA per day. After two months
of supplementation, the average cholesterol level in the treatment
group had fallen to a healthy 125 milligrams per decilitre
(mg/dl) of blood. The placebo group remained high, with an
average of 246 mg/dl. GLA has had similarly beneficial effects
on humans with high blood pressure. Research has demonstrated
that GLA supplementation also lowers stress-related
hypertension. In a 1996 study published in the Journal
of Human Hypertension[v], patients took 1 g of GLA per day
for 4 weeks. During subsequent stress-tests, the blood pressure
of the treatment group was up to 40% less than the placebo
group.
Evening primrose oil is rich in botanical triterpenes.
These hormone-like substances play an important role in immune
function and help fight viral infections. With free radical
scavenging properties, triterpenes also help to prevent oxidative
tissue damage.
Recent in vitro research suggests that evening primrose oil
may have certain anti-cancer properties[vi]. GLA has been
found to inhibit the action of a gene responsible for about
30% of breast cancers, by reducing the protein
produced by the gene which promotes tumour growth.
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