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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.

[i] Zurier RB, et al. Gamma-Linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis Rheum. 1996 Nov ;39(11):1808-17.

[ii] Puri, B.K., Chronic Fatigue Syndrome: A Natural Way to Treat M.E., (Hammersmith Press, London, 2005) ISBN 1-905140-00-2. p105.

[iii] Horrobin,D., Review of Contemporary Pharmacotherapy (1990) 1; 1-45.

[iv] Guivernau, M. et al. Clinical and Experimental Study on the Long-term Effect of Dietary Gamma Linolenic Acid on Plasma Lipids, Platelet Aggregation, Thromboxane Formation, and Prostacyclin Production. Prostaglandins, Leukotrienes and Essential Fatty Acids, Vol. 51, pp 311-316 (1994).

[v] Deferne, J-L. Resting blood pressure and cardiovascular reactivity to mental arithmetic in mild hypertensive males supplemented with blackcurrant seed oil. Journal of Human Hypertension, Vol. 10, pp 531-37 (1996).

[vi] Menendez, J.A., Vellon, L., Colomer, R., Lupu, R. Effect of -Linolenic Acid on the Transcriptional Activity of the Her-2/neu (erbB-2) Oncogene, JNCI, 2005, Volume 97, No. 21 Nov:1611-1615.