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葡萄乾的營養功效 - Raisins Nutrition
華人健康網 記者張世傑／台北報導 2013年1月17日 11:35
來源: 飛跑資訊首頁 2012-3-27 作者: gurrenlagann
兩份今天在美國心臟病學會會議提出的研究報告指出， 攝取葡萄乾和黃豆有助預防高血壓。高血壓是心臟疾病的關鍵風險因子。 一份研究對象為46名血壓稍高的前期高血壓患者， 他們每天分3次各攝取一把約60顆的葡萄乾，持續數週後， 試驗者的血壓數值降低。 這份隨機的臨床試驗是首份正式評估葡萄乾效益的研究。 研究人員不確定何以葡萄乾有這項功效， 但認為葡萄乾豐富的鉀含量可能是主因。 領導這份研究的路易斯維爾代謝與動脈粥狀硬化研究中心醫學主任貝斯 （Harold Bays）說：「葡萄乾含鉀成分高， 向來已知鉀能降低血壓。」 他說：「葡萄乾也是很好的抗氧化膳食纖維來源， 膳食纖維能降低血管硬化風險，也就能降低高血壓風險。」 另一份針對攝取黃豆有助降低血壓的研究，始於1985年， 對象為5100多名18至30歲的白種與非裔美國人， 研究根據試驗者自陳的飲食習慣數據。研究發現， 相較於每天攝取不到0.33毫克大豆異黃酮的試驗者， 每天攝取2.5以上毫克的民眾收縮壓明顯降低，平均能降低5.5毫米水銀。 大豆異黃酮是黃豆的主要成份。根據研究建議的日常攝取量， 對多數人來說都不難達到：1杯豆漿就有22毫克的大豆異黃酮， 是能達到見效毫克量的10倍。 哥倫比亞大學內外科學院畢業醫學生李察遜（Safiya Richardson） 領導這份研究，她表示：「這項研究充分顯示， 年輕的非裔與白種美國人只要攝取適度大豆異黃酮，就對血壓有好處。」 李察遜表示，對於高血壓前期患者，要避免惡化成高血壓， 攝取黃豆是個方法，甚至可能避免服用藥物。
攝取葡萄乾和黃豆有助預防高血壓？專家提醒，單一食物對健康的幫助有限；如果每天吃逾一百八十顆葡萄乾，恐怕熱量過高，徒增負擔。 台大醫院營養部主任鄭金寶說，葡萄乾或黃豆等食物除了豐富的鉀、大豆異黃酮之外，還有豐富的植物化學物質，有助控制血壓、血脂，還可抗癌。但她強調，前提是吃得「多元、均衡」，並減少攝取肉類等飽和脂肪。 鄭金寶提醒，該研究皆未說明研究對象其他的飲食條件；若每天攝取一百八十顆葡萄乾，少說也有六百大卡的熱量，其他熱量來源勢必得控制；豆漿富含大豆異黃酮，日飲一杯是不錯的選擇。
Raisins are made by dehydrating grapes in a process using the heat of the sun or a mechanical process of oven drying. Among the most popular types of raisins are Sultana, Malaga, Monukka, Zante Currant, Muscat and Thompson seedless. The size of small pebbles, raisins have wrinkled skins surrounding chewy flesh that tastes like a burst of sugary sweetness. While the colors of raisins vary, they are generally a deep brown color, oftentimes with hints of a purple hue.
This chart graphically details the %DV that a serving of Raisins provides for each of the nutrients of which it is a good, very good, or excellent source according to our Food Rating System. Additional information about the amount of these nutrients provided by Raisins can be found in the Food Rating System Chart. A link that takes you to the In-Depth Nutritional Profile for Raisins, featuring information over 80 nutrients, can be found under the Food Rating System Chart.
Raisins have been the object of phytonutrient research primarily for their unique phenol content, but these delicious dried grapes are also one of the top sources of the trace mineral, boron, in the U.S. diet.
Antioxidant Protection from Phenols
The phenols found in fruit have repeatedly been show to have antioxidant activity and to help prevent oxygen-based damage to cells in the body. The total antioxidant activity of many fruits and vegetables has been found to be exactly parallel to their total phenol content, and raisins take their place in this list right alongside prunes and apricots as an antioxidant-rich fruit. The flavonols (one type of phenol belonging to the flavonoid family) in raisins appear to be least affected by the grape-drying process, but raisins do contain fewer phenols than grapes since many of grape's phenols are largely lost in the conversion of grapes to raisins. These phenols include the hydroxycinnamics (caftaric and coutaric acids), procyanidins, and flavan-3-ols.
Boron for Better Bone Health
Although not often spotlighted in public health recommendations, boron is a mineral that is critical to our health, and has been of special interest in women in relationship to bone health and osteoporosis (bone softening). Boron is a trace mineral required to convert estrogen and vitamin D to their most active forms (17-beta-estradiol and 1,25-(OH)2D3 respectively). Estrogen levels drop after menopause causing osteoclasts to become more sensitive to parathyroid hormone, which signals them to break down bone. Studies have shown that boron provides protection against osteoporosis and reproduces many of the positive effects of estrogen therapy in postmenopausal women. Raisins are among the top 50 contributors to total dietary boron in the U.S. diet.
Protection against Macular Degeneration
Your mother may have told you carrots would keep your eyes bright as a child, but as an adult, it looks like fruit is even more important for keeping your sight. Data reported in a study published in the Archives of Ophthalmology indicates that eating 3 or more servings of fruit per day may lower your risk of age-related macular degeneration (ARMD), the primary cause of vision loss in older adults, by 36%, compared to persons who consume less than 1.5 servings of fruit daily.
In this study, which involved over 110,000 women and men, researchers evaluated the effect of study participants' consumption of fruits; vegetables; the antioxidant vitamins A, C, and E; and carotenoids on the development of early ARMD or neovascular ARMD, a more severe form of the illness associated with vision loss.
While, surprisingly, intakes of vegetables, antioxidant vitamins and carotenoids were not strongly related to incidence of either form of ARMD, fruit intake was definitely protective against the severe form of this vision-destroying disease. Three servings of fruit may sound like a lot to eat each day, but raisins can help you reach this goal. Add a handful of raisins to your morning cereal; lunch time yogurt; fruit, vegetable or green salads. Virtually any grain dish is improved by the addition of raisins and nuts.
When most fruits are dried, they keep their same name, but not the grape. The dried form of the grape, revered throughout history, has its own unique name: the raisin.
Raisins are made from dehydrating grapes in a process that either involves the heat of the sun or a mechanical process of oven drying. Among the most popular types of raisins are Sultana, Malaga, Monukka, Zante Currant, Muscat and Thompson seedless. The size of small pebbles, raisins have wrinkled skins surrounding chewy flesh that tastes like a burst of sugary sweetness. While the colors of raisins vary, they are generally a deep brown color, oftentimes with hints of a purple hue.
The scientific name for raisin (grape) is Vitus vinifera.
The drying of grapes into raisins has been practiced since ancient times. Raisins were produced in Persia and Egypt as early as 2,000 BC, with one of their first mentions being in the Old Testament. Murals from prehistoric times show that raisins were consumed and used as decorations in the Mediterranean region of Europe during that era. Raisins were also highly prized by the ancient Romans, who adorned their places of worships with them and used them as barter currency and as prizes for the winners of sporting events. In addition, raisins were oftentimes an integral item on the menus at Bacchanalian feasts. From ancient Rome, the practice of drying grapes into raisins subsequently spread throughout the world.
Currently, the largest commercial producer of raisins is California in a region known as the San Joaquin valley where raisins have been cultivated since the 19th century. The tale told of their introduction and subsequent popularity in California and the United States involves one enterprising grape grower who creatively responded to the forces of Nature. In 1873, when a heat wave destroyed the grape harvest, the grower took the dried grapes, the raisins, to a grocer in San Francisco whose attempts to sell this ancient delicacy were met with great response and demand, beginning the rise in popularity of the raisin in America. In addition to California, Australia, Turkey, Greece, Iran and Chile are among the leading commercial producers of raisins.
How to Select and Store
If possible, purchase raisins that are sold in bulk or in transparent containers so that you can judge their quality, checking to see that they are moist and undamaged. When buying raisins in a sealed, opaque container, make sure that the container is tightly sealed and that they are produced or packaged by a reputable company.
Storing raisins in the refrigerator in an airtight container will extend their freshness and prevent them from becoming dried out. If you purchase raisins in single serving boxes and do not want to transfer them to another container, store the boxes in the refrigerator to extend their shelf life. Raisins will be the most fresh if consumed within six months.
Tips for Preparing and Cooking
Tips for Preparing Raisins
Raisins that are fresh and have been stored properly will require no special attention prior to eating or using in a recipe. To restore dried out raisins before adding them to a recipe, place them in a bowl covered with a little hot water for a few minutes. You can use the nutrient-infused liquid in the recipe.
How to Enjoy
A Few Quick Serving Ideas
• Raisins are a great addition to homemade granola or can be sprinkled over any breakfast cereal, hot or cold.
• Soak raisins and other dried fruits in water to soften for an easy-to-make compote that is so versatile it can be served a variety of ways. Some of our favorites include served on top of chicken or layered with plain yogurt to make a dessert parfait.
• Raisins go well in most baked goods. Add them to bread, muffins and cookies.
• Add raisins, almonds, peppers and onions to brown rice to make a tasty side dish.
• Raisins' sweetness and texture make them a great addition to poultry stuffing.
• Mix raisins with your favorite nuts for a high-energy, protein and fiber-packed homemade snack or trail mix.
Raisins and Pesticide Residues
Virtually all municipal drinking water in the United States contains pesticide residues, and with the exception of organic foods, so do the majority of foods in the U.S. food supply. Even though pesticides are present in food at very small trace levels, their negative impact on health is well documented. The liver's ability to process other toxins, the cells' ability to produce energy, and the nerves' ability to send messages can all be compromised by pesticide exposure. According to the Environmental Working Group's 2009 report "Shopper's Guide to Pesticides in Produce," grapes imported into the U.S. (not domestically grown grapes) are among the 12 foods on which pesticide residues have been most frequently found. Therefore, individuals wanting to avoid pesticide-associated health risks may want to avoid consumption of imported grapes or raisins unless they are grown organically. While imported grapes were among the top 12 foods found to have pesticide residues, grapes grown in the U.S. were found to be number 21 among the 47 foods tested.
Raisins and Sulfites
Commercially grown dried raisins may be treated with sulfur dioxide gas during processing. They may also be treated with sulfites to extend their shelf life.
Sulfur-containing compounds are often added to dried foods like raisins as preservatives to help prevent oxidation and bleaching of colors. The sulfites used to help preserve dried raisins cause adverse reactions in an estimated one out of every 100 people, who turn out to be sulfite sensitive.
Sulfite reactions can be particularly acute in people who suffer from asthma. The Federal Food and Drug Administration estimates that 5 percent of asthmatics may suffer a reaction when exposed to sulfites.
Foods that are classified as "organic" do not contain sulfites since federal regulations prohibit the use of these preservatives in organically grown or produced foods. Therefore, concern about sulfite exposure is yet another reason to purchase organic foods.
Raisins are one of the richest sources of the mineral boron and provide concentrated amounts of polyphenolic phytonutrients.
In-Depth Nutritional Profile
In addition to the nutrients highlighted in our ratings chart, an in-depth nutritional profile for Raisins is also available. This profile includes information on a full array of nutrients, including carbohydrates, sugar, soluble and insoluble fiber, sodium, vitamins, minerals, fatty acids, amino acids and more.
Introduction to Food Rating System Chart
In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the nutrients for which this food is either an excellent, very good, or good source (below the chart you will find a table that explains these qualifications). If a nutrient is not listed in the chart, it does not necessarily mean that the food doesn't contain it. It simply means that the nutrient is not provided in a sufficient amount or concentration to meet our rating criteria. (To view this food's in-depth nutritional profile that includes values for dozens of nutrients - not just the ones rated as excellent, very good, or good - please use the link below the chart.) To read this chart accurately, you'll need to glance up in the top left corner where you will find the name of the food and the serving size we used to calculate the food's nutrient composition. This serving size will tell you how much of the food you need to eat to obtain the amount of nutrients found in the chart. Now, returning to the chart itself, you can look next to the nutrient name in order to find the nutrient amount it offers, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.