People with age-related macular degeneration （AMD） should eat oily fish at least twice a week to keep their eye disease at bay, say scientists.

    Omega-3 fatty acids found in abundance in fish like mackerel and salmon appear to slow or even halt the progress of both early and late stage disease.

    The researchers base their findings on almost 3,000 people taking part in a trial of vitamins and supplements.

    The findings are published in the British Journal of Ophthalmology.

    An estimated 500,000 people in the UK suffer from AMD, which destroys central vision.

    Protective

    Experts have already suggested omega-3 may cut the risk of getting AMD by a third, and now this latest work suggests these fats also benefit patients who already have the disease.

    Progression to both dry and wet forms of advanced AMD disease was 25% less likely among those eating a diet rich in omega-3 fatty acids.

    People with advanced AMD who also consumed a low-GI diet, eating of foods that release their sugar more slowly, and who took supplemental antioxidant vitamins and minerals like vitamin C and zinc appeared to reduce their risk of disease progression by even more - by up to 50%.

    Substituting five slices of wholegrain bread for white bread every day out of a total intake of 250g of carbohydrate might cut out almost 8% of advanced age related macular degeneration over five years, say the authors.

    Surprisingly, however, the supplements were counterproductive for those with early AMD, negating the benefits of omega-3 fats, and even appeared to increase the risk of disease progression.

    Those who took all the antioxidant vitamins plus zinc, and who a high daily intake of beta carotene - found in yellow and green vegetables - were 50% more likely to progress to advanced disease.

    The researchers at Tufts University, Boston, believe omega-3 fatty acids offer protection against AMD by altering fat levels in the blood after a meal that can be damaging to the body.

    'Moderation'

    But they say it is not clear whether patients should also consider taking supplements as well as omega-3 because of their mixed findings.

    They suggest that eating two to three servings of fatty fish, such as salmon, tuna, mackerel, shellfish, and herring every week, would achieve the recommended daily intake （650mg） of omega-3, substantially cutting the risk of both early and late stage AMD.

    The UK's Food Standards Agency says people should eat at least two portions of fish a week including one of oily fish.

    But they caution that too much oily fish is bad because it can contain low levels of pollutants that can build up in the body.

    Most people can safely eat up to four portions a week, but girls and women who might have a baby and those who are pregnant or breastfeeding should limit their intake to two portions a week.

    A spokeswoman from RNIB said good nutrition was very important for both general and eye health.

    "These findings appear to be consistent with previous research that has shown that eating omega-3 poly-unsaturated fats as part of a balanced diet may help prevent the development of age-related macular degeneration, the main cause of severe sight loss in the UK.

    "RNIB hopes that this will further highlight why looking after your eyes should be a key motivation in maintaining a healthy lifestyle," she said.

    科學家表示，患有老年性黃斑病變（AMD）眼疾的人，每星期至少要進食含油脂性的魚兩次，以保持眼睛健康。

    科學家在魚類如鯖魚及三文魚中發(fā)現(xiàn)大量的奧米加-3（Omega-3）脂肪酸，這些脂肪酸可以紓緩，甚至抑止眼疾初期及中期的擴展。

    研究員的研究結(jié)果是根據(jù)差不多3千名參加食用維他命及補充營養(yǎng)試驗的人得出來的。

    英國眼科期刊（British Journal of Ophthalmology）已刊登這項研究結(jié)果。

    英國估計約有50萬人患有會破壞中央視力的老年性黃斑病變。

    具保護作用

    專家早現(xiàn)表示奧米加-3可以減去患老年性黃斑病變?nèi)�分之一分的機會，而今次這項研究顯示，這脂肪酸對于已患上這眼疾的病人，同樣奏效。

    干性及濕性的中期老年性黃斑病變患者，飲食中含豐富奧米加-3脂肪酸，均減低病情25%.

    而患中期老年性黃斑病變的人，飲食中采用低GI值，吃一些釋放糖份較慢的食物，并進食補充抗氧維他命及礦物質(zhì)，如維他命C及鋅，他們病情改善高達五成，情況明顯。

    發(fā)表研究的作者們說，每天以五片全麥面包代替白面包，可取得共250克碳水化合物，五年內(nèi)可減去老年性黃斑病變8%.

    但最讓人感到驚訝的是，補充營養(yǎng)對初期老年性黃斑病變卻有反效果，會抵銷奧米加-3脂肪酸的果效，甚至似乎會令病情加重。

    一些進食抗氧維他命及鋅，和每天食用含大量胡蘿卜素的黃色及綠色蔬菜，有五成機會令病情變重。

    波士頓培夫斯（Tufts）大學的研究員認為，于餐后，奧米加-3脂肪酸能更改血液中的脂肪水平，以保護及對抗老年性黃斑病變。

    "中庸之道"

    但是由于研究結(jié)果混合多種情況，他們表示不太肯定病人應否同時食補充營養(yǎng)和奧米加-3.

    他們建議每周食用兩至三份油脂豐富的魚，如三文魚，吞拿魚，鯖魚，貝類及鯡魚，便可獲得每天建議食量（650毫克）的奧米加-3脂肪酸，大大減低早期及中期老年性黃斑病變的風險。

    英國食品標準署（The UK's Food Standards Agency）表示，人們應每周進食至少兩份魚，其中一份應包括含高油脂的魚。

    但他們警戒道，食用過量的含高油脂魚會有損健康，因為這些魚中含有低水平的污染物，這些污染物會在體內(nèi)積聚。

    大部分的人可放心一周進食四份含油脂的魚，有懷孕機會的女孩及婦女，孕婦及喂哺母乳的則應限制食量至一周兩份。

    （英國）皇家全國盲人協(xié)會（RNIB）發(fā)言人表示，充足營養(yǎng)對身體及眼睛健康都十分重要。

    「這些發(fā)現(xiàn)與之前研究顯示把奧米加-3多元不飽和脂肪酸作為均衡飲食一部份，有助預防老年性黃斑病變的結(jié)果一致，這疾病在英國是導致失明的主要成因。」

    她說：「皇家全國盲人協(xié)會希望今次進一步令大家明白，照顧雙目是保持健康生活一個重要源動力。」