健康飲食與降低女性核性白內障風險有關
作者：Laurie Barclay, MD
出處：WebMD醫學新聞
June 16, 2010 — 根據6月號眼科醫學誌(Archives of Ophthalmology)的一篇大型前瞻研究報告指出，健康飲食和女性核性白內障(nuclear cataract)風險較低有關。
威斯康辛大學的Julie A. Mares博士以及CAREDS (Carotenoids in Age-Related Eye Disease Study)研究的夥伴寫道，CAREDS是婦女健康研究(WHI)的附屬研究，目的在於評估類胡蘿蔔素葉黃素(carotenoids lutein)和黍黃素(zeaxanthin)與年紀相關的核性白內障以及老年性黃斑部病變(age-related macular degeneration)發生率之間的關係。
我們曾報告指出，飲食和血中的葉黃素及黍黃素值高，與該世代的核性白內障風險較低有關，迄今發表的研究很少同時評估其他營養風險因素與整體的生活型態、眼睛健康及生理風險因素。
該研究的目標在於確認健康飲食分數和核性白內障盛行率之間的關係，研究對象是參與WHI研究後4-7年、居住在愛荷華、威斯康辛與奧勒岡、年紀50-79歲的婦女。在1994至1998年間，研究者根據對飲食頻率問卷的回覆，計算1995 年健康飲食指數(1995 Healthy Eating Index (HEI-1995))這項分數，反映出對於1990年美國飲食指引的遵從性，較高的飲食分數表示攝取的蔬果、穀類、牛奶、肉類(或豆類、魚或蛋)大於等於建議攝取量，脂肪、飽和脂肪、膽固醇、鈉低於建議量。
從2001年5月1日至2004年1月31日，共有1808名婦女參與CARED評估其核性白內障，根據細隙燈攝影以及自我報告的白內障惡化，其中有736名婦女(41%)至少有一眼發生核性白內障。
研究的諸多風險因素中，HEI-1995分數高是核性白內障低發生率的最強可調控預測因子。比較飲食分數最高與最低五分之一這兩組，多變項校正勝算比為0.63 (95%信心區間為0.43 - 0.91)，核性白內障的其他可調控風險因素包括抽菸與明顯肥胖，不可調控因素包括褐色眼睛、近視以及高脈博壓，白內障盛行率不受補充維他命的影響。
研究作者們寫道，這些資料增加了證據，支持食用富含各種維他命與礦物質的飲食可以延後發生這種美國最常見的白內障。
研究限制包括，研究樣本是相對健康的婦女，評估核性白內障盛行率但是和發生率比較，未測量鉛曝露情況與其他風險因素，核性白內障可能有些分類錯誤。
研究作者結論表示，飲食是減少這類停經後婦女之核性白內障的最強風險因素，抽菸和肥胖也有影響。改善生活型態包括健康飲食、戒菸、避免肥胖，將可幫助年長美國女性減少白內障手術的需求和經濟負擔。
國家健康研究中心以及防盲研究等支持本研究。國家眼科研究中心提供CAREDS資金，國家心臟、肺臟與血液研究中心提供WHI計畫資金。研究作者之一曾擔任Eyetech的顧問，也擔任Alcon駐院外科課程的講師。
Healthy Diet Linked to Lower Risk for Nuclear Cataract in Women
By Laurie Barclay, MD
Medscape Medical News
June 16, 2010 — Healthy diet is linked to a lower risk for nuclear cataract in women, according to the results of a large, prospective study reported in the in the June issue of Archives of Ophthalmology.
"The Carotenoids in Age-Related Eye Disease Study (CAREDS), an ancillary study of the Women's Health Initiative (WHI), was designed in part to evaluate the relationships of the carotenoids lutein and zeaxanthin with the prevalence of age-related nuclear cataract and age-related macular degeneration," write Julie A. Mares, PhD, from University of Wisconsin, Madison, and colleagues from CAREDS.
"We previously reported that high dietary and blood levels of lutein and zeaxanthin were associated with lowered risk for nuclear cataract in this cohort. There are limited studies published to date in which nutritional risk factors are evaluated concurrently with a comprehensive set of other lifestyle, ocular health, and physical risk factors."
The goal of the study was to determine the relationship between healthy diet scores and the prevalence of nuclear cataract 4 to 7 years later in a sample of WHI participants, aged 50 to 79 years and living in Iowa, Wisconsin, and Oregon. At baseline in 1994 to 1998, the researchers calculated scores on the 1995 Healthy Eating Index (HEI-1995), reflecting adherence to 1990 US dietary guidelines, using responses to food frequency questionnaires. Higher diet scores resulted from intakes at or above recommended levels for vegetables, fruits, grains, milk, meat (or beans, fish, or eggs) and below recommended levels for fat, saturated fat, cholesterol, and sodium.
From May 1, 2001, to January 31, 2004, a total of 1808 women participating in CARED were evaluated for nuclear cataract, based on slit-lamp photographs and self-reports of cataract extractions. Nuclear cataract in at least 1 eye occurred in 736 women (41%).
Of numerous risk factors studied, a high HEI-1995 score was the strongest modifiable predictor of low prevalence of nuclear cataract. For high vs low quintile for diet score, the multivariate-adjusted odds ratio was 0.63 (95% confidence interval, 0.43 - 0.91). Other modifiable risk factors for nuclear cataract were smoking and marked obesity, and nonmodifiable factors were brown eyes, myopia, and high pulse pressure. Prevalence of cataract was not affected by vitamin supplement use.
"These data add to the body of evidence suggesting that eating foods rich in a variety of vitamins and minerals may contribute to postponing the occurrence of the most common type of cataract in the United States," the study authors write.
Limitations of this study include relatively healthy women comprising the sample, evaluation of prevalence vs incidence of nuclear cataract, lack of measurement of lead exposure and some other risk factors, and some possible misclassification of nuclear cataract.
"Diet was the strongest risk factor related to reduced risk of nuclear cataract in this sample of postmenopausal women," the study authors conclude. "Smoking and obesity were also contributors. Lifestyle improvements that include healthy diets, smoking cessation, and avoiding obesity may substantively lower the need for and economic burden of cataract surgery in aging American women."
The National Institutes of Health and by Research to Prevent Blindness supported this study. The National Eye Institute provided funding for the CAREDS, and the National Heart, Lung and Blood Institute provided funding for the WHI program. One of the study authors has served as an advisory board consultant for Eyetech and as a speaker for Alcon resident surgery course.
Arch Ophthalmol. 2010;128:738-749.
