Walnut | |
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Scientific classification |
A walnut is an edible seed of any tree of the genus Juglans, especially the Persian walnut, Juglans regia. Broken nutmeats of the eastern black walnut are also commercially available in small quantities, as are foods prepared with butternut nutmeats.
Contents |
Medical benefits and claims
Raw walnuts contain glyceryl triacylates of the n-3 fatty acid alpha-linolenic acid (ALA),[1] which is not as effective in humans as long-chain n-3 fatty acids,[2] and (mostly insoluble) antioxidants.[3][4][5][6][7] Roasting reduces antioxidant quality.[8] In 2010, a report[citation needed] published in the Journal of the American College of Nutrition said that walnuts and walnut oil improve reaction to stress.[9]
A study has suggested that consumption of walnuts increases fat oxidation and reduces carbohydrate oxidation without affecting total consumption, suggesting that walnut consumption may improve the use of body fat in overweight adults.[10] Walnuts have been shown to decrease the endothelial dysfunction associated with a high-fat meal.[11] Aged rats fed diets containing 2% to 6% walnuts showed reversal of age-associated motor and cognitive function, but a 9% walnut diet impaired performance, suggesting a J curve.[12]
On October 11, 2006, ScienceDaily published a report[13] which stated "New research shows that consuming a handful of raw walnuts along with meals high in saturated fat appears to limit the ability of the harmful fat to damage arteries," and attributed the result to a 2006 article in the Journal of the American College of Cardiology. The lead researcher, Emilio Ros, MD, PhD, was quoted as saying "People would get the wrong message if they think that they can continue eating unhealthy fats provided they add walnuts to their meals."[13] Funding for the study was provided by the California Walnut Commission, an industry marketing agency.[13]
Medicinal uses
Scientists are not yet certain whether walnuts act as a cancer chemopreventive agent, an effect which may be a result of the fruit's high phenolic content, antioxidant activity, and potent in vitro antiproliferative activity.[14]
Compared to certain other nuts, such as almonds, peanuts and hazelnuts, walnuts (especially in their raw form) contain the highest total level of antioxidants, including both free antioxidants and antioxidants bound to fiber.[4]
Meaning and etymology
"Walnut" does not distinguish the tree from other species of Juglans. Other names include common Walnut in Britain; Persian walnut in South Africa[15] and Australia;[16] and English walnut in North America and Great Britain,[17] New Zealand,[18] and Australia,[16] the latter name possibly because English sailors were prominent in Juglans regia nut distribution at one time.[19] Alternatively, Walter Fox Allen stated in his 1912 treatise What You Need to Know About Planting, Cultivating and Harvesting this Most Delicious of Nuts:[20] "In America, it has commonly been known as English walnut to distinguish it from our native species."
Etymologically, the word derives from the Germanic wal- and Old English wealhhnutu, literally "foreign nut", wealh meaning "foreign" (wealh is akin to the terms Welsh and Vlach; see Walha).[21] For the walnut to be identified as a "foreign" nut by Anglo-Saxons arriving in the fifth century, native Britons must have passed to them the tradition that it had been introduced to England from Gaul and Italy.[original research?]
See also
References
- ^ "Omega-3 Fatty Acids". Tufts University. http://www.tufts.edu/med/nutrition-infection/hiv/health_omega3.html. Retrieved 4 April 2011.
- ^ Charles, Deborah (21 April 2009). "Want to reduce breast cancer risk? Eat walnuts". Reuters. http://www.reuters.com/article/2009/04/21/us-cancer-breast-walnut-idUSTRE53K52820090421. Retrieved 4 April 2011. ""Scientists have been unsure whether the types found in nuts and leafy green vegetables work as well as the omega-3 fatty acids found in fish oil.""
- ^ Arranz, Sara; Pérez-Jiménez, Jara; Saura-Calixto, Fulgencio (2007). "Antioxidant capacity of walnut (Juglans regia L.): Contribution of oil and defatted matter". European Food Research and Technology 227 (2): 425–31. doi:10.1007/s00217-007-0737-2.
- ^ a b "Walnuts are top nut for heart-healthy antioxidants". American Chemical Society (Anaheim). 27 March 2011. http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_ARTICLEMAIN&node_id=222&content_id=CNBP_026930&use_sec=true&sec_url_var=region1&__uuid=cb42b928-3506-4523-96f5-32836654369f. Retrieved 9 October 2011.
- ^ "Ask the Expert: Omega-3 Fatty Acids". Harvard University. 21 April 2009. http://www.hsph.harvard.edu/nutritionsource/questions/omega-3/index.html. Retrieved 4 April 2011. ""Omega-6 fatty acids lower LDL cholesterol (the "bad" cholesterol) and reduce inflammation, and they are protective against heart disease. So both omega-6 and omega-3 fatty acids are healthy. While there is a theory that omega-3 fatty acids are better for our health than omega-6 fatty acids, this is not supported by the latest evidence. Thus the omega-3 to omega-6 ratio is basically the "good divided by the good," so it is of no value in evaluating diet quality or predicting disease.""
- ^ "Cholesterol: Top 5 foods to lower your numbers". Mayo Clinic. http://www.mayoclinic.com/health/cholesterol/CL00002. Retrieved 4 April 2011.
- ^ Park, Alice (29 March 2011). "The Supernut: Walnuts Pack a Powerful Dose of Antioxidants". Time (magazine). http://healthland.time.com/2011/03/29/the-supernut-walnuts-pack-a-powerful-dose-of-antioxidants/. Retrieved 4 April 2011.
- ^ "Walnuts are the healthiest nut, say scientists". BBC News. 27 March 2011. http://www.bbc.co.uk/news/health-12865291. Retrieved 28 March 2011.
- ^ "Eating Walnuts With High-Fat Meals Helps To Protect Arteries Against Short-Term Damage". 4 October 2010. http://www.sciencedaily.com/releases/2010/10/101004101141.htm. Retrieved 4 April 2011.
- ^ Tapsell, L; Batterham, M; Tan, SY; Warensjö, E (2009). "The effect of a calorie controlled diet containing walnuts on substrate oxidation during 8-hours in a room calorimeter". Journal of the American College of Nutrition 28 (5): 611–7. PMID 20439557.
- ^ Cortés, Berenice; Núñez, Isabel; Cofán, Montserrat; Gilabert, Rosa; Pérez-Heras, Ana; Casals, Elena; Deulofeu, Ramón; Ros, Emilio (2006). "Acute Effects of High-Fat Meals Enriched With Walnuts or Olive Oil on Postprandial Endothelial Function". Journal of the American College of Cardiology 48 (8): 1666–71. doi:10.1016/j.jacc.2006.06.057. PMID 17045905.
- ^ Willis, Lauren M.; Shukitt-Hale, Barbara; Cheng, Vivian; Joseph, James A. (2008). "Dose-dependent effects of walnuts on motor and cognitive function in aged rats". British Journal of Nutrition 101 (08): 1140–4. doi:10.1017/S0007114508059369.
- ^ a b c "Eating Walnuts With High-Fat Meals Helps To Protect Arteries Against Short-Term Damage". 11 October 2006. http://www.sciencedaily.com/releases/2006/10/061010022750.htm. Retrieved 4 April 2011.
- ^ Negi, Arvind Singh; Luqman, Suaib; Srivastava, Suchita; Krishna, Vinay; Gupta, Namita; Darokar, Mahendra Pandurang (2011). "Antiproliferative and antioxidant activities of Juglans regia fruit extracts". Pharmaceutical Biology 49 (6): 669–73. doi:10.3109/13880209.2010.537666. PMID 21554010.
- ^ L.C. van Zyl "Grafting of Walnut (Juglans regia L.) with Hot Callusing Techniques Under South African Conditions", University of the Free State, 2009 http://etd.uovs.ac.za/ETD-db//theses/available/etd-09172009-160603/unrestricted/VanZylLC.pdf
- ^ a b http://www.austnuts.com.au/walnuts.html
- ^ D.S. Hill, Skegness, Lincs, United Kingdom: Pests of Crops in Warmer Climates and Their Control p.651, Springer Science+Business Media, 2008
- ^ http://www.nzplantpics.com/not_nz_trees.htm
- ^ "?". http://www.agmrc.org/agmrc/commodity/nuts/englishwalnut/englishwalnutsprofile.htm.[dead link]
- ^ "?". http://walnutsweb.com/walnuts/How+to+Grow+English+Walnuts.[dead link]
- ^ Online Etymology Dictionary - "Walnut"