Healthy Ingredients

English Walnut

Introduction

The English walnut is the most popular and widely used nut throughout the world.1 It is the fruit of a deciduous tree that can get up to 120 feet in height and 12 feet in diameter.2,3,4 The blooms appear in late spring and early summer and are followed by dark green fruits.2 Originally from the Near East,5 walnuts have been cultivated for centuries in Europe, North Africa, East Asia, and North America.3,6 The major countries that produce walnuts are China, the U.S., Iran, Turkey, and Ukraine, but they grow in many other countries as well.7 The English walnut is different from the black walnut (J. nigra) and white walnut or butternut (J. cinerea), both of which are native to the eastern U.S.3 The leaves, bark, fruits or nuts, kernels, and oil can be used.2

History and Cultural Significance

The genus name Juglans comes from Jovis glans or Jupiter’s nuts because of the ancient belief that during the “golden age” gods ate walnuts while the common people ate acorns.4,8 The species name regia means royal and refers to the walnut’s attractive appearance and historical importance as timber and food.4

The English walnut is called the Persian walnut everywhere except the U.S.1 The Romans considered the walnut to be Persian because it was introduced to Italy from Persia.4,8 A walnut was cultivated in ancient Greece but a superior cultivated variety came from Persia to Greece.9 The origin is difficult to discern because the walnut is so widespread now.4 Most likely it was cultivated first in Southeast Europe and Asia Minor up to the Himalayas.4 The name English walnut came about because the English shipped walnuts around the world from Mediterranean countries in the mid-14th century.1,4

In traditional Roman weddings, it was customary for the bridegroom to throw walnuts for good health, to ward off disease, and to increase fertility.4 In contrast, Romanian brides that did not want children placed a roasted walnut in their bodice to remain childless. During the Middle Ages, Europeans used walnut branches to ward off lightning, fevers, witchcraft, the evil eye, and epileptic fits. In China, musically trained singing crickets, considered a good omen, were carried in intricately carved walnut shells.4

Walnuts have a variety of culinary applications. Walnut meal is a thickening agent in the food industry.2 Walnuts can be eaten green, half-ripe, ripe and processed many different ways including as a milk alternative.4,9 Walnut oil is used as an expensive, traditional salad and cooking oil in France, Switzerland, and Northern Italy.9 It becomes rancid quickly and needs heavy refining for commercial use, so it is rarely available and consumption is limited.4,5 Walnut leaf is approved in the U.S. as a natural flavoring in food.10

Walnut wood is made into furniture, veneer, and gunstocks.2 The leaves repel insects, and combined with the husks can be made into a lawn wormicide that doesn’t kill grass.8 The kernel oil is used to polish and varnish wood.8 Walnut leaf oil is not currently produced commercially, but it shows promise as an essential oil in men’s fragrances and in flavoring foods.11 Walnut oil is used in cosmetics and artists’ paints.2 Mineral bath and hair care products contain extracts of walnut leaf.10 Walnut extract is an old-fashioned hair dye used alone or in combination with henna.12 Its leaves and husks yield a full, rich, warm brown dye for hair tints and conditioners.2,12 Roma people stained their skin brown with the dye.8

Since the meat of the walnut appears to be shaped like a human brain, some traditional, plant-based medical systems used them to treat brain injuries and mental illness.1 In India, a leaf decoction was used as a wash for malignant sores and pustules.6 Traditional Chinese medicine used a tonic internally for weak kidney energy.2 Walnuts have also been used internally for gastrointestinal, skin, circulatory, and lung conditions.2,3,5,10 In folk medicine, it was considered a “blood purifier” and was believed to eliminate worms, poison, and anemia.10,13
In traditional medicine, walnut leaves were used externally in bathing, dressing, and/or rinse forms as an astringent and emollient for various skin conditions such as acne, eczema, herpes, fungal infection, itchiness, inflammation, burns, hair loss, ulcers and perspiration.2,3,5,6,10 A decoction was made for bedbugs and lice.3

The commercial preparation consists of dried leaves5 which contain tannins that give it an astringent action.6,13,14 One of the chemicals, juglone, demonstrates antiviral, antibacterial, and antifungal activities.5,6 The German Commission E has approved walnut leaf for external use in mild, superficial inflammations of the skin and excessive perspiration of the hands and feet.13

Modern Research

There are a few human clinical intervention trials that show a heart healthy diet with walnuts can lower blood cholesterol levels.15 One human clinical study suggests Juglans regia chewing sticks are effective as an aid in maintaining oral hygiene due to antibacterial properties.16

Future Outlook

Market trends show increasing consumption and production of walnuts.7 Production tends to fluctuate over years due to the alternate bearing cycles of walnut trees.17 California harvests were low at 208,000 tons in 1996 and 227,000 tons in 1998, but increased to 325,000 tons in 2004.17 Walnut values increased 16 percent to $439 million dollars from 2003 to 2004.18 Exports from California accounted for 40 percent of harvested crops in 2004 valuing $240.7 million.17

References
1 Wood R. The New Whole Foods Encyclopedia: A Comprehensive Resource for Healthy Eating. New York: Penguin Putnam Inc; 1999.
2 Bown D. The Herb Society of America New Encyclopedia of Herbs and Their Uses. London: Dorling Kindersley Ltd.; 2001.
3 Van Wyk BE, Wink M. Medicinal Plants of the World. Portland, OR: Timber Press; 2004.
4 Onstad D. Whole Foods Companion: A Guide for Adventurous Cooks, Curious Shoppers & Lovers of Natural Foods. White River Junction, VT: Chelsea Green Publishing Company; 1996.
5 Bruneton J, ed. Pharmacognosy, Phytochemistry, Medicinal Plants. 2nd ed. Paris: Lavoisier; 1999.
6 Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Austin, TX: American Botanical Council; Newton, MA: Integrative Medicine Communications; 2000.
7 World Horticultural Trade & U.S. Export Opportunities. World Walnut Situation & Outlook. Available at: http://www.fas.usda.gov/htp/Hort_Circular/2004/04-30-04/04-04%20Walnut%20Update.pdf. Accessed August 25, 2005.
8 Grieve M. A Modern Herbal. Vol. 2. New York: Dover Books; 1971.
9 Davidson A. The Oxford Companion to Food. London: Oxford University Press; 1999.
10 Wichtl M, Brinckmann J. Herbal Drugs and Phytopharmaceuticals. Stuttgart: Medpharm GmbH Scientific Publishers; 2004.
11 Arctander S. Perfume and Flavor Materials of Natural Origin. Carol Stream, IL: Allured Publishing Corporation; 1994.
12 D’Amelio FS. Botanicals: A Phytocosmetic Desk Reference. Boca Raton, FL: CRC Press LLC; 1999.
13 Blumenthal M, Busse WR, Goldberg A, Gruenwald J, Hall T, Riggins CW, Rister RS, eds. Klein S, Rister RS, trans. The Complete German Commission E Monographs¾Therapeutic Guide to Herbal Medicines. Austin, TX: American Botanical Council; Boston: Integrative Medicine Communication; 1998.
14 Tyler VE, Robbers JE, eds. Tyler’s Herbs of Choice. 2nd ed. Binghamton, NY: Haworth Herbal Press; 1999.
15 Feldman EB. The scientific evidence for a beneficial health relationship between walnuts and coronary heart disease. J Nutr 2002;132(5):1062S-1101S.
16 Jagtap AG and Karkera SB. Extract of Juglandaceae regia inhibits growth, in-vitro adherence, acid production and aggregation of Streptococcus mutans. J Pharm Pharmacol. 2000;52(2):235-42.
17 Brunke H and Miller M. English Walnuts Profile: Overview. Available at: http://www.agmrc.org/agmrc/commodity/nuts/englishwalnut/englishwalnutsprofile.htm. Accessed August 25, 2005.
18 National Agricultural Statistics Service. Noncitrus Fruits and Nuts: 2004 Summary: July 2005. Available at: http://usda.mannlib.cornell.edu/reports/nassr/fruit/pnf-bb/ncit0705.txt. Accessed August

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