Science Daily — 吃開心果（pistachios）不只讓您心情開心，連身體也跟著開心。因為根據研究指出，每日食用一小撮的開心果可以降低體內的膽固醇（cholesterol），同時也可以提供類似像是食用了深色蔬菜或色彩鮮豔的水果中所含有的抗氧化劑一般讓您的身體更健康。
圖1. 開心果 pistachios
圖2. 開心果樹 pistachios tree
「只要一到兩小撮 － 大約也就是 1.5 到 3 盎司左右的開心果數量，就可以大幅降低造成心血管疾病主因之一的低密度膽固醇（LDL）的含量。如果在高劑量的食用下，亦可降低脂蛋白的比例。」Sarah K. gebauer 這樣說到。他是生物科學的研究生，並在參與四月 30 日於華盛頓特區舉辦的生物實驗會議中做出了這樣的表示。
圖3. 膽固醇化學結構
圖4. 膽固醇結晶（圖片來源：http://www.scienceclarified.com/Ca-Ch/Cholesterol.html）
研究人員進行了一項隨機抽樣、交叉設計的食物攝取研究實驗，這是為了要進行食用開心果會對心血管造成什麼樣影響的研究。因為我們都知道飲食中若包含了太多的脂肪將大幅提昇心血管疾病的風險。藉著控制食物攝取實驗則提供了在研究期間，依照研究計畫來攝取特定食物的控制。
圖5. 血液中 LDL 及 HDL 所造成的影響
參與受試者將藉著食用平均美國飲食組成的食物 － 包含有 35% 的總脂肪以及 11% 的飽和脂肪共兩個星期。接著在四周內測試三種飲食狀況，每兩週將打破一次飲食習慣。
所有飲食的第一階段是使用膽固醇含量較低的飲食。所謂而第一階段飲食包含以下各組：飲食中不包含開心果，同時有 25% 的總脂肪及 8% 的飽和脂肪；以及每天 1.5 盎司的開心果，30% 的總脂肪以及 8% 的飽和脂肪酸；每日 3 盎司的開心果，包含 34% 總脂肪以及 8%的飽和脂肪。研究人員將開心果加入飲食當中，包含在餐包當中含有一半數量的開心果或是加入像是開心果鬆餅、granola 麥片及開心果醬（pistachio pesto）這類的食物。
圖6. 含有開心果的義大利脆餅
圖7. 開心果鬆餅
圖8. 開心果鬆餅
「我們有相當願意配合的受試者願意遵照我們所需要的飲食來攝取。」Gebauer 這樣說到。
標準血液測試是測試這些參與實驗者在攝取飲食之後血液中膽固醇的含量。研究人員發現，3 盎司的開心果可以降低血液中總膽固醇的數量大約 8.4%，此外，低密度脂蛋白的數量也降低了 11.6%，這些低密度脂蛋白被稱為壞的膽固醇。研究還發現一些非高密度脂蛋白（non-HDL）也降低了 11.2%。非高密度脂蛋白是用來評估心血管疾病罹患率的風險因子。
食用 3 盎司的開心果也同時降低了總膽固醇對 HDL、LDL 對 HDL 以及非高密度脂蛋白對 HDL 及 apolipoprotein B 等三項比值。這些都是是否罹患心血管疾病風險的量測。「我們也發現針對攝取兩種不同開心果劑量對於脂蛋白比值所出現的差別，因為這代表開心果確實會產生一些影響，同時它們所發揮的作用也是劑量依賴（dose dependent）的關係。」
圖9. LDL 及 HDL 構造
此外，在研究其間，研究人員也注意到飲食過程裡，因抗氧化劑存在於血液中而發生的 LDL 被氧化現象之影響。
「我們正嘗試著去瞭解如果增加抗氧化劑的程度是否與開心果的存在與否有關，開心果是否可以減低發炎及氧化的現象？」Gebauer 說到。開心果中含有許多的葉黃素（lutein）－ 這個成分通常會存在於深色蔬菜中，beta-胡蘿蔔素（beta carotene）－ 維他命 A 的前驅物，以及 gamma 生育醇（gamma tocopherol）－ 主要會形成維生素 E，等成分比其他堅果來得豐富。LDL 及其他脂蛋白的氧化會造成動脈阻塞（圖 5）。
圖10. 葉黃素（Lutein）、beta-胡蘿蔔素（beta-carotene）以及 gamma-生育醇（gamma-tocopherol）化學結構
圖11. 屬於深色蔬菜之一的紫花椰菜
圖12. 屬於深色蔬菜的花椰菜
研究人員發現，跟一般飲食比較起來，不管是每天食用 1.5 盎司的開心果或是 3 盎司的開心果，均可以降低 LDL 氧化現象的發生。富含開心果的飲食同時也明顯的增加了血液中葉黃素的含量。尤其是食用 3 盎司的實驗組中，葉黃素量增加的特別明顯，同時也與降低了 LDL 氧化現象息息相關。這也許指出了存在於開心果中的葉黃素確實可以藉由降低 LDL 的氧化來改善心血管疾病的風險。
「我們的研究顯示食用開心果是一種能心臟健康的飲食，也許可以降低人們罹患 CDV 的風險。」Penny Kris-Etherton 博士這樣說到，他是本研究中主要的研究人員，同時也是營養學特聘教授。
Researchers conducting the cholesterol study included Gebauer; Kris-Etherton; Colin D. Kay, former Penn State post-doctoral associate now at the University of East Anglia; UK; Sheila G. West, associate professor of biobehavioral health, all at Penn State, and P. Alaupovic, Oklahoma Medical Research Foundation, Oklahoma City. Researchers conducting the oxidation study included Kay, Gebauer, West and Kris-Etherton. The California Pistachio Commission supported this study. Partial support also came from the NIH-supported GCRC at Penn State.
Note: This story has been adapted from a news release issued by Penn State.
原始報導：
ScienceDaily：Pistachios Lower Cholesterol, Provide Antioxidants
相關報導：
Nuts Cut Coronary Heart Disease Risk
Date: May 9, 2001
Science Daily — University Park, Pa. --- In the most comprehensive review yet of the available epidemiological and clinical evidence, Penn State researchers have concluded that eating tree nuts or peanuts can have a strong protective effect against coronary heart disease. Dr. Penny Kris-Etherton, distinguished professor of nutrition and lead author of the review, says, "To date, five large epidemiologic studies and 11 clinical studies have demonstrated that frequent consumption of nuts decreases the risk of coronary heart disease."
圖13. 各式各樣的堅果可以有效預防動脈心血管疾病
The most improvement comes with adding very small amounts of nuts an ounce, or about three to four tablespoons, five or more times a week.
"However, you can't simply add nuts, nut butters or nut oils to your usual diet without making some adjustments," Kris-Etherton says. "You have to replace some of the calories you usually consume with nuts and substitute the unsaturated fat in nuts for some of the saturated fat in your diet."
The study was published today (May 8) in the current issue of the journal, Nutrition Reviews. Kris-Etherton's co-authors are Guixiang Zhao, a doctoral candidate and a Kligman Scholar in Nutrition; Amy E. Binkoski, doctoral candidate in Penn State's Life Sciences Consortium; Stacie M. Coval, master's degree candidate; and Dr. Terry Etherton, distinguished professor and head of the dairy and animal sciences department.
The researcher's review of the existing published epidemiologic studies shows that consuming 1 ounce of nuts more than 5 times/week can result in a 25 to 39 percent reduction in coronary heart disease risk among people whose characteristics match those of the general adult U.S. population.
Among the nuts consumed by the people who took part in the epidemiologic studies were almonds, brazil nuts, cashews, hazelnuts, macademia nuts, pecans, pistachios, and walnuts, as well as peanuts. However, the effects of specific nuts on coronary heart disease risk were not evaluated in these studies due to difficulties in classifying consumption patterns of specific nuts and because of the small number of cases in each category. In typical American diets, peanuts account for approximately half of all nuts consumed.
The 11 clinical studies reviewed by the Penn State researchers focused on the blood cholesterol-lowering effects of nuts. Collectively, these studies showed that including nuts in a blood cholesterol-lowering diet has favorable effects. However, the researchers write, "Whether the inclusion of nuts evokes a greater cholesterol-lowering response than would be expected from a typical lipid-lowering diet remains to be resolved."
Calculations conducted by the researchers using the published data suggest that nuts may contain other cholesterol-lowering constituents, but studies are needed to corroborate this. Nuts studied in clinical investigations included walnuts, almonds, macadamia nuts, pecans, pistachio nuts and peanuts.
Nuts are a rich source of unsaturated fatty acids, the "good" fats, and are low in saturated fatty acids, the "bad" fats. However, the researchers concluded that the fatty acid profile of nuts contributes to only part of the total reduction in coronary heart disease risk.
The Penn State researchers write, "Nuts are a source of plant protein dietary fiber, antioxidant vitamins, minerals and numerous bioactive substances that may have health benefits. It is conceivable, although not proven, that many nutrients in nuts may act synergistically to exert beneficial effects."
They conclude that it is appropriate to recommend inclusion of nuts in a healthy diet that meets energy needs to reduce risk of coronary heart disease. They emphasize the need to provide dietary guidance to help people understand how to plan heart healthy diets that include nuts.
Dr. Kris-Etherton notes that dietary guidance on fats has changed in recent years from removing or drastically restricting fats to substituting and replacing them with heart healthy alternatives. For example, she says, "you can cut back a little on margarine and add a small amount of slivered almonds on green beans. You can flavor a salad with a few walnuts and use less dressing. Or, you could use peanut butter instead of full fat cream cheese on a bagel."
Note: This story has been adapted from a news release issued by Penn State.
相關報導之原始出處：
ScienceDaily：Nuts Cut Coronary Heart Disease Risk