English Walnut - Juglans regia

Detailed Description

A time-honored fruit featured in countless herbal and botanical texts.

Botanical Information

The English Walnut, Juglans regia, is a stately, deciduous broadleaf tree that typically reaches heights of 25–35 meters and trunk diameters up to 2.5 meters, with lifespans often exceeding 200 years. Despite the tree’s broad canopy, its stature is relatively moderate. Its bark ranges from olive-brown to dark gray-black, with rough surface and scattered fissures, while branches are greenish-brown or gray. The distinctive branches are hollow, containing air pockets. Leaves are pinnate, sturdy, and dark green, generally 10–20 cm long and 5–10 cm wide, smooth, elongated, and composed of five to nine leaflets. All parts of the walnut, except for the mature kernel, possess a characteristic aroma.

Walnut flowers are unisexual. Male flowers grow as elongated, thick, yellow-green catkins on last year’s twigs, while female flowers exhibit two-lobed stigmas. In the Czech Republic, walnuts bloom in April and May. The tree begins bearing fruit after approximately 15 years. The fruit is the familiar walnut, with a fleshy husk and a hard, stony shell. The seed coat is thin, and the lobed kernel is white to pale yellow. A healthy, mature tree in full bearing can yield up to 50 kg of nuts annually. The nuts mature and naturally fall in autumn.

Origin and Distribution

The English Walnut’s native range is likely the Balkans, more definitively in the Near East or Central Asia. The most commonly cited wild origins are in Xinjiang province in western China, spread over time to Kazakhstan, Uzbekistan, southern Kyrgyzstan, the lower parts of Nepal, Bhutan, Tibet, northern India, Afghanistan, Pakistan, Turkmenistan, Iran, Armenia, Georgia, and eastern Turkey.

Today, the English Walnut is one of the most widely cultivated trees—from Western Europe to the Himalayan foothills. As early as Roman times, humans intentionally expanded the walnut’s distribution, introducing it to western and northern Europe. In Central Europe, it has been present since the Bronze Age, and in the seventeenth century, settlers brought it to North America.

Major production regions are found between 30° and 50° north latitude and between 30° and 40° south latitude. In Europe, notable producers include France, Bulgaria, Hungary, Romania, and Greece; also Baja California and Coahuila in Mexico, California in the USA, China in Asia, and Chile in South America. Cultivation has since extended to southeastern Australia and New Zealand.

Usage / Dosage

The English Walnut is cherished not only for its nuts but also as a honey plant, for the pleasant shade its canopy provides, and for its high-quality, durable, and fast-growing wood. Artisans value walnut wood for its strength, luster, and shimmer, using it in flooring, musical instruments, furniture, and rifle stocks.

Walnuts are a staple in baking, can be eaten alone, and are used to make walnut oil, walnut brandy, and walnut liqueur. However, walnuts are a source of potent allergens that can, in rare cases, cause life-threatening reactions.

Several parts of the English Walnut are used in herbal medicine. Fresh leaves—harvested in June—can be prepared as a decoction to support digestion, relieve constipation, and boost appetite. Historic herbal texts from Central Europe recommend walnut leaves for jaundice and diabetes, and traditional European usage includes lowering blood sugar, easing skin inflammation, treating acne and rashes, reducing excessive sweating, and combating head lice.

The green husk, collected in July and August before ripening, is similarly used but considered more potent. Green walnuts, easily pierced, are macerated in spirits for traditional walnut liqueur, used to purify the blood, support digestion, and alleviate bloating. Austrian folk medicine recommends walnut spirits in optimal doses for liver support.

In English folk medicine, regular walnut consumption was traditionally viewed as a way to cleanse the body and blood (for instance, after food poisoning) and to soothe inflammatory digestive processes. Walnut paste was applied to skin infections, dermatitis, or swelling around the eyes or hard-to-reach areas.

Scandinavian tradition also suggests external use of compresses made from walnut decoction or crushed kernels for acne, eczema, and excessive sweating; and, when taken internally, as a support for mild anemia and ulcerative conditions.

Mature, nearly dried kernels can be boiled (about five minutes with the shell, then left to steep) for a decoction used against dry cough, and the cooked nuts can be eaten afterward. Extracts and cold-pressed oil from mature kernels appear in cosmetics and pharmaceuticals for irritated or problem skin. Walnut extract is common in sunscreens and tanning oils due to its juglone content, which interacts with skin amino acids to form yellow to brown pigments—these also help repel insects.

Walnut kernels are high in vitamin E, making them a recommended food for moistening the lungs (easing mucus-laden coughs), to prevent premature graying of hair, and enhance hair color. Their mix of protein and unsaturated fatty acids is optimal for brain metabolism, nourishing brain cells and potentially boosting cognitive activity.

Certain compounds extracted from walnut kernels have been tested for reducing fatigue and combat stress. The oily components help moisten and lubricate dry intestines, contributing to the treatment of constipation. Other substances from English Walnut have shown possible cough-suppressant (antitussive) effects in animal studies.

Specific walnut oils have been shown to increase body weight in human volunteers after extended consumption. Standardized walnut kernel extracts increased plasma proteins (albumins) and reduced overall cholesterol.

In vitro studies highlight certain walnut constituents’ ability to limit cholesterol absorption in the small intestine. Chemical analyses describe a capacity to dissolve cholesterol, "clean" vascular walls, and enhance circulation. Thus, walnuts may help prevent atherosclerosis and reduce cholesterol and some symptoms of insulin-dependent diabetes.

Evidence suggests that people whose diets favor walnuts over other nuts tend to maintain lower plasma cholesterol and reduced risk of coronary diseases. When combined with a low-calorie, low-fat diet, regular walnut kernel consumption reportedly decreased overall cholesterol by 4–12% and LDL cholesterol by 8–16% in healthy volunteers and some patients with type 2 diabetes.

Extracts have demonstrated antioxidant and antiproliferative activity thanks to the high content of polyphenols. Walnut kernels are used in Austrian folk medicine for diabetes, both as teas, tinctures, and as fresh nuts. Some walnut compounds also have anti-inflammatory effects.

One substance from the walnut kernel, in animal studies, was able to inhibit the progression of S37 tumors and reduce the growth of cancer cells in esophageal, gastric, nasopharyngeal, lung, thyroid, and lymphosarcoma tumors. In further research, it increased white blood cell counts and protected liver tissue in cancer-affected subjects after prolonged administration.

Alternative Medicine

The ancient Shen Nong Ben Cao Jing regarded walnuts as a premier tonic for extending life, slimming the body, and boosting vitality (qi). Generations of physicians have valued walnut kernels as one of nature’s most useful remedies for a broad variety of ailments. The Compendium of Materia Medica (Ben Cao Gang Mu) ranks both fresh and mature walnuts among "qi tonics" and blood boosters.

Yu Yao Yuan Fang (Imperial Prescriptions) recommended regular walnut consumption to "fill the vessels with blood" and support the formation of bone marrow. Older Chinese texts suggest walnuts maintain overall health, hydrate the skin, and darken the hair. Walnuts also have some application in homeopathy, in diluted forms.

According to the Chinese Pharmacopeia, walnuts are sweet and warming, benefiting the kidney, lung, and large intestine meridians—purifying the lungs and moistening the bowels. In modern traditional Chinese medicine, primary indications for walnuts or their extracts include erectile dysfunction, breathing difficulties (and related cough), and constipation. Other herbal combinations are used to support kidney function, relieve nausea and tinnitus, and address a sensation of incomplete urination.

Both traditional Chinese and Western medicine agree that walnuts should be avoided during diarrheal complaints and possibly with prostate cancer due to an alpha-linolenic acid derivative that may be negatively linked to this type of cancer.

Active Compounds

English walnuts are rich in organic acids and their derivatives (such as caffeic acid and neo-chlorogenic acid), quinones (juglone, hydrojuglone), terpenes (notably germacrene D), flavonoids (quercetin, kaempferol), tannins and their derivatives (gallic and ellagic acid), vitamins and pro-vitamins (beta-carotene, vitamin C, E, B3, B5, B6), and major minerals (especially potassium, phosphorus, magnesium).

Walnuts are very nutritious and high in calories, containing about 70% fat (62–71% per chemical analyses), mostly in the form of unsaturated fatty acids (21–40% oleates, 44–60% linolates, 7–12% linoleates), along with 18% protein and roughly 3% carbohydrates.

Traditional Dosage

There is no specific recommended or optimal daily amount of English walnuts for adults or children; traditional use relies on common sense and moderation.