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Monday, February 6, 2006
Orange
Juicy and sweet and renowned for its concentration of vitamin C, oranges make the perfect snack and add a special tang to many recipes; it is no wonder that they are one of the most popular fruits in the world. Oranges are generally available from winter through summer with seasonal variations depending on the variety.
Oranges are round citrus fruits with finely-textured skins that are, of course, orange in color just like their pulpy flesh; the skin can vary in thickness from very thin to very thick. Oranges usually range from approximately two to three inches in diameter.
- Health Benefits
- Description
- History
- How to Select and Store
- How to Enjoy
- Safety
- Nutritional Profile
- References
Health Benefits
Oranges' Healing Phytonutrients
In recent research studies, the healing properties of oranges have been associated with a wide variety of phytonutrient compounds. These phytonutrients include citrus flavanones (types of flavonoids that include the molecules hesperetin and naringenin), anthocyanins, hydroxycinnamic acids, and a variety of polyphenols. When these phytonutrients are studied in combination with oranges' vitamin C, the significant antioxidant properties of this fruit are understandable.
But it is yet another flavanone in oranges, the herperidin molecule, which has been singled out in phytonutrient research on oranges. Arguably, the most important flavanone in oranges, herperidin has been shown to lower high blood pressure as well as cholesterol in animal studies, and to have strong anti-inflammatory properties. Importantly, most of this phytonutrient is found in the peel and inner white pulp of the orange, rather than in its liquid orange center, so this beneficial compound is too often removed by the processing of oranges into juice.
A Healthy Dose of Vitamin C for Antioxidant Protection and Immune Support
You may already know that oranges are an excellent source of vitamin C - just one orange supplies 116.2% of the daily value for vitamin C - but do you know just how important vitamin C and oranges are for good health? Vitamin C is the primary water-soluble antioxidant in the body, disarming free radicals and preventing damage in the aqueous environment both inside and outside cells. Inside cells, a potential result of free radical damage to DNA is cancer. Especially in areas of the body where cellular turnover is especially rapid, such as the digestive system, preventing DNA mutations translates into preventing cancer. This is why a good intake of vitamin C is associated with a reduced risk of colon cancer.
Free radical damage to other cellular structures and other molecules can result in painful inflammation, as the body tries to clear out the damaged parts. Vitamin C, which prevents the free radical damage that triggers the inflammatory cascade, is thus also associated with reduced severity of inflammatory conditions, such as asthma, osteoarthritis, and rheumatoid arthritis.
Free radicals also oxidize cholesterol. Only after being oxidized does cholesterol stick to the artery walls, building up in plaques that may eventually grow large enough to impede or fully block blood flow, or rupture to cause a heart attack or stroke. Since vitamin C can neutralize free radicals, it can help prevent the oxidation of cholesterol.
Vitamin C, which is also vital for the proper function of a healthy immune system, is good for preventing colds and may be helpful in preventing recurrent ear infections. Owing to the multitude of vitamin C's health benefits, it is not surprising that research has shown that consumption of vegetables and fruits high in this nutrient is associated with a reduced risk of death from all causes including heart disease, stroke and cancer.
Protection against Cancer and Cardiovascular Disease
A 248-page report, "The Health Benefits of Citrus Fruits," released December 2003 by Australian research group, CSIRO (The Commonwealth Scientific and Industrial Research), reviews 48 studies that show a diet high in citrus fruit provides a statistically significant protective effect against some types of cancer, plus another 21 studies showing a non-significant trend towards protection.
Citrus appears to offer the most significant protection against esophageal, oro-phayngeal/laryngeal (mouth, larynx and pharynx), and stomach cancers. For these cancers, studies showed risk reductions of 40 – 50%.
The World Health Organization's recent draft report, "Diet, Nutrition and the Prevention of Chronic Disease," concludes that a diet that features citrus fruits also offers protection against cardiovascular disease due to citrus fruits' folate, which is necessary for lowering levels of the cardiovascular risk factor, homocysteine; their, potassium, which helps lower blood pressure, protecting against stroke and cardiac arrhythmias; and the vitamin C, carotenoids and flavonoids found in citrus fruits, all of which have been identified as having protective cardiovascular effects.
One large US study reviewed in the CSIRO report showed that one extra serving of fruit and vegetables a day reduced the risk of stroke by 4%, and this increased by 5-6 times for citrus fruits, reaching a 19% reduction of risk for stroke from consuming one extra serving of citrus fruit a day.
The CSIRO Report also includes evidence of positive effects associated with citrus consumption in studies for arthritis, asthma, Alzheimer's disease and cognitive impairment, Parkinson's disease, macular degeneration, diabetes, gallstones, multiple sclerosis, cholera, gingivitis, optimal lung function, cataracts, ulcerative colitis and Crohn's disease.
Finally, the CSIRO Report notes that as low fat, nutrient dense foods with a low glycemic index, citrus fruits are protective against overweight and obesity, conditions which increase the risk of heart disease, certain cancers, diabetes, high blood pressure and stroke, and add to symptoms of other conditions like arthritis.
An orange has over 170 different phytochemicals and more than 60 flavonoids, many of which have been shown to have antiinflammatory, anti-tumour and blood clot inhibiting properties, as well as strong antioxidant effects.
Phytochemicals, specifically, the class of polyphenols, are high in citrus with oranges containing 84mg Gallic Acid equivalents/100mg. The polyphenols so abundant in oranges have been shown to have a wide range of antioxidant, anti-viral, anti-allergenic, anti-inflammatory, anti-proliferative and anti-carcinogenic effects. Although most of the research has centered on citrus polyphenols' possible role in cancer and heart disease, more recently, scientists have begun to look at their role in brain functions such as learning and memory.
An increasing number of studies have also shown a greater absorption of the nutrients in citrus when taken not as singly as supplements, but when consumed within the fruit in which they naturally appear along with all the other biologically active phytonutrients that citrus fruits contain. The Health Benefits of Citrus Fruits," released December 2003 by Australian research group, CSIRO (The Commonwealth Scientific and Industrial Research Organization. If you would like to read more, click CSIRO
Long-Acting Liminoids in Citrus Add to Their Cancer Protective Properties
In animal studies and laboratory tests with human cells, compounds in citrus fruits, including oranges, called limonoids have been shown to help fight cancers of the mouth, skin, lung, breast, stomach and colon. Now, scientists from the US Agricultural Research Service have shown that our bodies can readily absorb and utilize a very long-acting limonoid called limonin that is present is citrus fruits in about the same amount as vitamin C.
In citrus fruits, limonin is present in the form of limonin glucoside, in which limonin is attached to a sugar (glucose) molecule. Our bodies easily digest this compound, cleaving off the sugar and releasing limonin.
In the ARS study, 16 volunteers were given a dose of limonin glucoside in amounts ranging from those that would be found in from 1 to 7 glasses of orange juice. Blood tests showed that limonin was present in the plasma of all except one of the subjects, with concentrations highest within 6 hours after consumption. Traces of limonin were still present in 5 of the volunteers 24 hours after consumption!
Limonin's bioavailability and persistence may help explain why citrus limonoids are potent anti-carcinogens that can continuously prevent cancerous cells from proliferating. Other natural anti-carcinogens are available for much less time; for example, the phenols in green tea and chocolate remain active in the body for just 4 to 6 hours.
Possible Cholesterol-Lowering Benefits
The ARS team are now investigating the potential cholesterol-lowering effects of limonin. Lab tests indicate that human liver cells produce less apo B when exposed to limonin. Apo B is a structural protein that is part of the LDL cholesterol molecule and is needed for LDL production, transport and binding, so higher levels of apo B translate to higher levels of LDL cholesterol.
Compounds in Orange Peel May Lower Cholesterol as Effectively as Statin Drugs
A class of compounds found in citrus fruit peels called polymethoxylated flavones (PMFs) have the potential to lower cholesterol more effectively than some prescription drugs, and without side effects, according to a study by U.S. and Canadian researchers that was published in the May 2004 issue of the Journal of Agricultural and Food Chemistry.
In this study, when hamsters with diet-induced high cholesterol were given the same diet containing 1% PMFs (mainly tangeretin), their blood levels of total cholesterol, VLDL and LDL (bad cholesterol) were reduced by 19-27 and 32-40% respectively. Comparable reductions were also seen when the hamsters were given diets containing a 3% mixture of two other citrus flavonones, hesperidin and naringin.
Treatment with PMFs did not appear to have any effect on levels of beneficial HDL cholesterol, and no negative side effects were seen in the animals fed the PMF-containing diets.
Although a variety of citrus fruits contain PMFs, the most common PMFs, tangeretin and nobiletin, are found in the peels of tangerines and oranges. Juices of these fruits also contain PMFs, but in much smaller amounts. In fact, you'd have to drink about 20 glasses of juice each day to receive an amount of PMFs comparable in humans to that given to the hamsters. However, grating a tablespoon or so of the peel from a well-scrubbed organic tangerine or orange each day and using it to flavor tea, salads, salad dressings, yogurt, soups, or hot oatmeal, buckwheat or rice may be a practical way of achieving some cholesterol-lowering benefits. The researchers are currently exploring the mechanism of action by which PMFs lower cholesterol. Based on early results in cell and animal studies, they suspect that PMFs work like statin drugs, by inhibiting the synthesis of cholesterol and triglycerides inside the liver.
A Very Good Source of Fiber
Oranges' health benefits continue with their fiber; a single orange provides 12.5% of the daily value for fiber, which has been shown to reduce high cholesterol levels thus helping to prevent atherosclerosis. Fiber can also help out by keeping blood sugar levels under control, which may help explain why oranges can be a very healthy snack for people with diabetes. In addition, the natural fruit sugar in oranges, fructose, can help to keep blood sugar levels from rising too high after eating. The fiber in oranges can grab cancer-causing chemicals and keep them away from cells of the colon, providing yet another line of protection from colon cancer. And the fiber in oranges may be helpful for reducing the uncomfortable constipation or diarrhea in those suffering from irritable bowel syndrome. In addition to oranges' phytonutrients, vitamin C and fiber, they are a good source of thiamin, folate, vitamin A (in the form of beta-carotene), potassium and and calcium.
Prevent Kidney Stones
Want to reduce your risk of calcium oxalate kidney stones? Drink orange juice. A study published in the August 2003 issue of the British Journal of Nutrition found that when women drank � to 1 litre of orange, grapefruit or apple juice daily, their urinary pH value and citric acid excretion increased, significantly dropping their risk of forming calcium oxalate stones.
Help Prevent Ulcers and Reduce Risk for Stomach Cancer
An orange a day may help keep ulcers away, according to a study published in the August 2003 issue of the Journal of the American College of Nutrition . In this study, researchers evaluated data from 6,746 adults enrolled in the Third National Health and Nutrition Examination Survey from 1988-1994. Study participants with the highest blood levels of vitamin C had a 25% lower incidence of infection with Helicobacter pylori, the bacterium responsible for causing peptic ulcers and in turn, an increased risk for stomach cancer. Researchers are uncertain whether H. pylori lowers blood levels of vitamin C or if high blood levels of vitamin C help protect against infection—either way, eating an orange or drinking a glass of orange juice each day may help prevent gastric ulcers. Lead researcher in this study, Dr. Joel A. Simon at the San Francisco VA Medical Center, urges people who have tested positive for H. pylori to increase their consumption of vitamin C-rich foods since this may help them combat H. pylori infection.
Lower Your Risk of Developing Lung Cancer
Consuming foods rich in beta-cryptoxanthin, an orange-red carotenoid found in highest amounts in oranges, corn, pumpkin, papaya, red bell peppers, tangerines, and peaches, may significantly lower one's risk of developing lung cancer. A study published in the September 2003 issue of Cancer Epidemiology, Biomarkers and Prevention reviewed dietary and lifestyle data collected from 63,257 adults in Shanghai, China, who were followed for 8 years, during which time 482 cases of lung cancer were diagnosed. Those eating the most crytpoxanthin-rich foods showed a 27% reduction in lung cancer risk. When current smokers were evaluated, those who were also in the group consuming the most cryptoxanthin-rich foods were found to have a 37% lower risk of lung cancer compared to smokers who ate the least of these health-protective foods.
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 June 2004 issue of the Archives of Opthamology 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 77,562 women and 40,866 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 ARM, a more severe form of the illness associated with vision loss. Food intake information was collected periodically for up to 18 years for women and 12 years for men. While, surprisingly, intakes of vegetables, antioxidant vitamins and carotenoids were not strongly related to incidence of either form of ARM, 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 oranges can help you reach this goal. Start your day with a freshly quartered orange. Add orange slices to your green as well as fruit salads. Before broiling, top any fish dish with orange slices.
Protection against Rheumatoid Arthritis
While one July 2004 study suggests that high doses of supplemental vitamin C makes osteoarthritis, a type of degenerative arthritis that occurs with aging, worse in guinea pigs, another indicates that vitamin C-rich foods, such as oranges, provide humans with protection against inflammatory polyarthritis, a form of rheumatoid arthritis involving two or more joints.
The findings, presented in the Annals of the Rheumatic Diseases were drawn from a study of more than 20,000 subjects who kept diet diaries and were arthritis-free when the study began, and focused on 73 subjects who developed inflammatory polyarthritis and 146 similar subjects who remained arthritis-free during follow-up between 1993 and 2001. Subjects who consumed the lowest amounts of vitamin C-rich foods were more than three times more likely to develop arthritis than those who consumed the highest amounts.
New research published in the August 2005 issue of the American Journal of Clinical Nutrition adds to the evidence that enjoying a daily glass of freshly squeezed orange juice can significantly lower your risk of developing rheumatoid arthritis.
Data collected by the European Prospective Investigation of Cancer Incidence (EPIC)-Norfolk study, a population-based, prospective study of over 25,000 subjects, showed that study participants with the highest daily intake of the carotenoids, zeaxanthin and Î’-cryptoxanthin, had a much lower risk of developing rheumatoid arthritis compared to individuals consuming the least of these beneficial phytonutrients. Those whose intake of zeaxanthin was highest were 52% less likely to develop rheumatoid arthritis, while those with the highest intake of cryptoxanthin had a 49% reduction in risk. Pretty dramatic benefits for doing something as simple as enjoying a glass of freshly squeezed orange juice each day!
Description
Oranges are one of the most popular fruits around the world. While they are delightful as a snack or as a recipe ingredient, for many Americans, it is their juice that is most associated with good health, having a reputation for being an integral part of a healthy breakfast.
Oranges are round citrus fruits with finely-texturized skins that are, of course, orange in color just like their pulpy flesh. They usually range from about two to three inches in diameter.
Oranges are classified into two general categories – sweet and bitter – with the former being the type most commonly consumed. Popular varieties of the sweet orange ( Citrus sinensis) include Valencia, Navel and Jaffa oranges, as well as the blood orange, a hybrid species that is smaller in size, more aromatic in flavor and has red hues running throughout its flesh. Bitter oranges ( Citrus aurantium) are oftentimes used to make jam or marmalade, and their zest serves as the flavoring for liquers such as Grand Marnier and Cointreau.
History
Oranges originated thousands of years ago in Asia, in the region from southern China to Indonesia from which they spread to India. Although Renaissance paintings display oranges on the table in paintings of The Last Supper, the assumption that they were grown in this region at this time seems to be erroneous since oranges were not cultivated in the Middle East until sometime around the 9th century. Sweet oranges were introduced into Europe around the 15th century by various groups including the Moors, and Portuguese and Italian traders and explorers who found them on their voyages to Asia and the Middle East.
Orange trees began to be grown in the Caribbean Islands in the late 15th century after Christopher Columbus brought the seeds there on his second voyage to the New World. Spanish explorers are responsible for bringing oranges to Florida in the 16th century, while Spanish missionaries brought them to California in the 18th century, beginning the cultivation of this citrus fruit in the two states widely known for their oranges.
Before the 20th century, oranges were very expensive and therefore they were not regularly consumed, but rather eaten on special holidays such as Christmas. After more efficient means of transportation were developed, and food processors invented methods for utilizing orange by-products such as citric acid and bioflavonoids, the price of oranges dropped, and they could be consumed on a wide scale, as they are today. Currently, the countries that are some of the largest commercial producers of oranges include the United States, Brazil, Mexico, Spain, China and Israel.
How to Select and Store
Oranges do not necessarily have to have a bright orange color to be good. In fact, the uniform color of non-organic oranges may be due to injection of Citrus Red Number 2 (an artificial dye) into their skins at the level of 2 parts per million. Whether organic or not, oranges that are partially green or have brown russetting may be just as ripe and tasty as those that are solid orange in color. Avoid those that have soft spots or traces of mold. And, because oranges are among the top 20 foods in which pesticide residues are most frequently found, buy organic oranges whenever possible.
Choose oranges that have smoothly textured skin and are firm and heavy for their size. These will have a higher juice content than those that are either spongy or lighter in weight. In general, oranges that are smaller will be juicier than those that are larger in size, as will those that feature thinner skins.
Oranges can either be stored at room temperature or in the refrigerator, depending upon your preference. They will generally last the same amount of time, two weeks with either method, and will retain nearly the same level of their vitamin content. The best way to store oranges is loose rather than wrapped in a plastic bag since if exposed to moisture, they can easily develop mold.
Orange juice and zest can also be stored for later use. Place freshly squeezed orange juice in ice cube trays until frozen, then store them in plastic bags in the freezer. Dried orange zest should be stored in a cool, dry place in an airtight glass container.
How to Enjoy
For some of our favorite recipes, click Recipes.
Tips for Preparing Oranges:
Oranges can be eaten as a snack - just peel and enjoy. Before cutting the orange in half horizontally through the center, wash the skin so that any dirt or bacteria residing on the surface will not be transferred to the fruit. Proceed to cut the sections into halves or thirds, depending upon your personal preference.
Thin-skinned oranges can be easily peeled with your fingers. For easy peeling of the thicker skinned varieties, first cut a small section of the peel from the top of the orange. You can then either make four longitudinal cuts from top to bottom and peel away these sections of skin, or starting at the top, peel the orange in a spiral fashion.
Oranges are oftentimes called for in recipes in the form of orange juice. As oranges, like most citrus fruits, will produce more juice when warmer, always juice them when they are at room temperature. Rolling the orange under the palm of your hand on a flat surface will also help to extract more juice.
The juice can be extracted in a variety of ways. You could either use a juicer or do it the old fashioned way, squeezing by hand.
If your recipe calls for orange zest, make sure that you use an orange that is organically grown since most conventionally grown fruits will have pesticide residues on their skin and may be artificially colored. After washing and drying the orange, use a zester, paring knife or vegetable peeler to remove the zest, which is the orange part of the peel. Make sure not to remove too much of the peel as the white pith underneath is bitter and should not be used. The zest can then be more finely chopped or diced if necessary.
A Few Quick Serving Ideas:
Healthy saut� onions and ginger, then deglaze the pan with orange juice. Use this liquid as a sauce for salmon or tuna.
Orange segments, fennel and boiled beets make a delightfully refreshing salad.
Gently simmer sweet potatoes, winter squash and orange segments in orange juice. Before serving, sprinkle with walnuts.
Safety
Allergic Reactions to Oranges
Oranges are a food more commonly associated with food allergy than other foods. Although allergic reactions can occur to virtually any food, research studies on food allergy consistently report more problems with some foods than with others. Common symptoms associated with an allergic reaction to food include: chronic gastrointestinal disturbances; frequent infections, e.g., ear infections, bladder infections, bed-wetting; asthma, sinusitis; eczema, skin rash, acne, hives; bursitis, joint pain; fatigue, headache, migraine; hyperactivity, depression, insomnia.
Individuals who suspect food allergy to be an underlying factor in their health problems may want to avoid commonly allergenic foods, including oranges. Other foods commonly associated with allergic reactions include: cow's milk, wheat, soy, shrimp, eggs, chicken, strawberries, tomato, spinach, peanuts, pork, corn and beef.These foods do not need to be eaten in their pure, isolated form in order to trigger an adverse reaction. For example, yogurt made from cow's milk is also a common allergenic food, even though the cow's milk has been processed and fermented in order to make the yogurt. Ice cream made from cow's milk would be an equally good example.
Nutritional Profile
Introduction to Food Rating System Chart
The following chart shows the nutrients for which this food is either an excellent, very good or good source. Next to the nutrient name you will find the following information: the amount of the nutrient that is included in the noted serving of this food; the %Daily Value (DV) that that amount represents (similar to other information presented in the website, this DV is calculated for 25-50 year old healthy woman); the nutrient density rating; and, the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. Read detailed information on our Food and Recipe Rating System.
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In Depth Nutritional Profile for Orange
References
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- Ensminger AH, Ensminger, ME, Kondale JE, Robson JRK. Foods & Nutriton Encyclopedia. Pegus Press, Clovis, California.
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- Fan Y, Ding Z, Yang L, et al. [A preliminary study on bioactivity of orange and tangerine peel extracts against aphis and mites]. Zhongguo Zhong Yao Za Zhi 1995 Jul;20(7):397-8, 446.
- Fortin, Francois, Editorial Director. The Visual Foods Encyclopedia. Macmillan, New York.
- Galati EM, Monforte MT, Kirjavainen S, et al. Biological effects of hesperidin, a citrus flavonoid. (Note I): antiinflammatory and analgesic activity. Farmaco 1994 Nov;40(11):709-12.
- Galati EM, Trovato A, Kirjavainen S, et al. Biological effects of hesperidin, a Citrus flavonoid. (Note III): antihypertensive and diuretic activity in rat. Farmaco 1996 Mar;51(3):219-21.
- Honow R, Laube N, Schneider A, Kessler T, Hesse. Influence of grapefruit-, orange- and apple-juice consumption on urinary variables and risk of crystallization. Br J Nutr. Aug;90(2):295-300.
- Khaw KT, Bingham S, Welch A, et al. Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study. European Prospective Investigation into Cancer and Nutrition. Lancet. 2001 Mar 3;357(9257):657-63.
- Kurl S, Tuomainen TP, Laukkanen JA et al. Plasma vitamin C modifies the association between hypertension and risk of stroke. Stroke 2002 Jun;33(6):1568-73.
- Kurowska EM, Manthey JA. Hypolipidemic effects and absorption of citrus polymethoxylated flavones in hamsters with diet-induced hypercholesterolemia. J Agric Food Chem. 2004 May 19;52(10):2879-86. .
- Pattison DJ, Silman AJ, Goodson NJ, Lunt M, Bunn D, Luben R, Welch A, Bingham S, Khaw KT, Day N, Symmons DP. Vitamin C and the risk of developing inflammatory polyarthritis: prospective nested case-control study. Ann Rheum Dis. 2004 Jul;63(7):843-7.
- Rapisarda P, Tomaino A, Lo Cascio R, et al. Antioxidant effectiveness as influenced by phenolic content of fresh orange juices. J Agric Food Chem 1999 Nov;47(11):4718-23.
- Simon JA, Hudes ES, Perez-Perez GI. Relation of serum ascorbic acid to Helicobacter pylori serology in US adults: the Third National Health and Nutrition Examination Survey. J Am Coll Nutr. Aug;22(4):283-9.
- Stange RR Jr, Midland SL, Eckert JW, Sims JJ. An antifungal compound produced by grapefruit and Valencia orange after wounding of the peel. J Nat Prod 1993 Sep;56(9):1627-9.
- Wood M. Citrus Compound, Ready to Help Your Body!. Agricultural Research, February 2005.
- Wood, Rebecca. The Whole Foods Encyclopedia. New York, NY: Prentice-Hall Press; 1988.
- Yuan JM, Stram DO, Arakawa K, Lee HP, Yu MC. Dietary cryptoxanthin and reduced risk of lung cancer: the Singapore Chinese Health Study. Cancer Epidemiol Biomarkers Prev. 2003 Sep;12(9):890-8.
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