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 奧米加三六九(Omega 3-6-9)的分別及其好處 Benefits of Essential Fatty Acids (EFAs) 
 
目前最廣為研究的奧米加脂肪酸包括有奧米加三、六、九脂肪酸,其中奧米加三和奧米加六是人體必須脂肪酸(EFAs)。奧米加九嚴格來說不屬於EFA,但奧米加九對人體也有相當多好處,故也在這裏作個簡介。

奧米加三 Omega 3
身體將最基本的奧米加三脂肪酸alpha linolenic acid(LNA)轉化成eicosapentaenoic acid(EPA),然後再轉化成docosahexaenoic acid(DHA)。愛斯基摩人的生長環境逼使他們以動物飽和脂肪為主要食物來源,但出乎意料地他們患有心血管疾病的比率甚至比一般人低,究其原因,可能與他們的飲食中含高分量的EPA有關。EPA普遍存在於北極冰水魚類,這些EPA能有效抵消飽和脂肪對身體的潛在威脅,預防血小板凝聚而導致血脈堵塞。EPA也有強化血小板細胞壁的作用,進一步保護心臟免受心臟病發和中風等威脅。

DHA是由LNA轉化的另一種衍生物,人體腦部和神經系統都含大量DHA。 DHA能有效保護神經元,確保身體的各種神經信號能正確傳達至目的地。由於這種保護作用隨年月而流逝,身體需從飲食中(或透過服用DHA補充劑)攝取額外奧米加3脂肪酸,以延續腦部和神經系統保護作用。 DHA也是視網膜的主要組成部分, 所以對維系正常視力也扮演非常重要的角色。

人體必須脂肪酸EFAs在維持心理健康方面也非常重要。 抑鬱症僅是其中一項與腦部EFAs過低有關的精神病症。 由唐納德盧丁醫生領導的一個研究發現,「奧米加3脂肪酸令人類行為有所改善,並能獲得更良好的感覺」。 許多患者「也體驗了生理上的問題得到改善。因此,補充奧米加脂肪酸能帶來很多好處,包括心境也變得安寧了」。

奧米加六 Omega 6s

亞油酸(LA)是首要的奧米加6脂肪酸。LA被吸收以後,身體將之轉化為gamma linolenic acid (GLA), arachidonic acid (AA), 和 conjugated linoleic acid (CLA)。 GLA和AA是荷爾蒙類物質(例如前列腺素等)的重要組成部分,而這些物質正控制大部分維持生命的各類系統所用。由於身體不能保存前列腺素,故每日必須消耗一定水平的EFAs以符合制造前列腺素所需。另外,腦部必須有 AA才能維持健康,而GLA則對濕疹、牛皮癬、關節炎和哮喘等過敏及發炎症狀有舒緩作用。 GLA也可通過增加體內脂肪燃燒而促進瘦身效果。

奧米加九 Omega 9s

嚴格來說奧米加9不算是EFAs,但這種單元非飽和脂肪酸對維持身體健康也非常重要,她有助於減少患乳癌風險和促進奧米加3脂肪酸在血液中的作用。奧米加九對肥胖一族則更為重要,她能使人有溫飽感覺,對那些兩餐之間常覺得餓的人非常重要,能減少那些無益的甜食和含反式脂肪的零食。

Benefits of Essential Fatty Acids (EFAs)

Three of the best-researched omega fats are the omega 3s, omega 6s, and omega 9s. Both the omega-3 and omega-6 families of oils are made up of essential fatty acids. The omega 9s are not considered true EFAs, but they are included here because of their health-supporting properties.

Omega 3s. The body converts the primary omega-3 fatty acid alpha linolenic acid (LNA) into eicosapentaenoic acid (EPA) and then into docosahexaenoic acid (DHA). EPA is the fatty acid responsible for the low level of cardiovascular disease found in the Eskimo population, even though that native diet is high in saturated fats. The EPA in cold-water fish blocks the potentially damaging effects of saturated fats by preventing blood platelets from clumping together and clogging arteries. EPA has also been found to strengthen platelet walls, which offers further protection from heart attack and stroke.

The second derivative of LNA, DHA is the most prevalent fat in the brain and nervous system. It cushions the neurons, ensuring that the body's electrical signals will reach their destinations easily. As the cushioning erodes over time, the body needs to have enough dietary omega-3 oils (or you need to take DHA supplements) to keep the brain and nervous system protected. As the primary building block of the retina, DHA is also critical for vision and plays a direct role in the healthy functioning of the eye.

EFAs also have a role in psychological health. Depression is just one of the disorders linked to low brain levels of essential fatty acids. In a group of study patients, reports Donald Rudin, MD, "Omega-3 fatty acids produced improved behavior [and] contributed to feelings of well-being." Many of these patients "also experienced a lessening of their physical problems. Thus, there are many possible benefits from omega oil supplementation, including greater peace of mind."

Omega 6s. Linoleic acid (LA) is the foremost omega-6 fatty acid. After LA is absorbed, the body converts it into gamma linolenic acid (GLA), arachidonic acid (AA), and conjugated linoleic acid (CLA). GLA and AA are important as raw materials for production of some of the prostaglandins, the hormone-like substances that control the functioning of most of the body's life-sustaining systems. Because the body cannot store prostaglandins, sufficient levels of EFAs must be consumed daily to meet the body's prostaglandin requirements.

In addition, AA must be present in the brain for healthy functioning, and GLA helps to combat allergy symptoms and inflammatory diseases such as eczema, psoriasis, arthritis, and asthma. GLA also can promote weight loss by increasing the body's fat-burning ability.

Omega 9s. While not technically EFAs, the monounsaturated fatty acids, omega 9s, are critical for maintaining heart health, reducing breast cancer risk, and boosting the effects of the omega-3 fatty acids in the blood. For those among us who are struggling with extra weight, the monounsaturated omega 9s play an important role in creating a significant satiety response. This helps us guard against between-meal cravings for sugar and the unhealthful trans fats in processed foods.

 
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