Juglans regia, or better known as walnut or Hu Tao, is native to Qiang Hu, northwest of ancient China. That is the reason why it is named “Hu” in mandarin, which actually is a general term for northwest China’s ancient minorities, especially Qiang and Hun ethnic minorities. It was introduced into Central Plains by envoy Zhang Qian when he was set a diplomatic mission to Xiyu (the west of ancient China). Walnut is a lot of people’s favorite snack and often used as stuffing in moon cake and glue pudding. Walnut is also considered a tonic that nourishes kidney, warms lung, and lubricates the intestines. More than that, besides of its large edible nut, this plant is widely cultivated for the juglans regia wood, a type of durable and hard timber that is frequently used for making furniture. However, the medicinal uses of its nuts are our main concern here.
What are juglans regia?
Medicinally it refers to the kernel of Juglans regia L., a plant in the family Juglandaceae. Other common names of this plant also include the Persian walnut, English walnut, common walnut, and so on. But this species is a little bit different from the Black Walnut (J. nigra). The former is native to Persia and the latte is originated from eastern North America. Today in China it is cultivated all over the country, especially in north, northwest and northeast regions. The ripe fruits are usually harvested in September to October. Next, remove the fleshy pericarp, dry in the sun, crack the hard shell and take the seeds. Medicinally it is used raw of fried.
Walnut tree is one of desiduous trees, 20 to 25 meters high. Bark is gray, smooth when young and with shallow longitudinal cracks when old. Twigs are covered with short glandular hairs, with obvious lenticels. Odd pinnately compound leaf is alternate, 40 to 50cm long. Leaflets are usually 5 to 9 pieces, but 13 sometimes. Flowers are unisexual, bloom simultaneously with leaves. Fruits are nearly spherical, drupaceous, and 4 to 6cm in diameter. Its blooming period is from May to June, and fruiting time is from September to October.
Main chemical constituents of its nuts are fatty oil that mainly contains linoleic acid glycerides, proteins, carbohydrates, calcium, phosphorus, and so on.
Juglans regia benefits
This plant, in particular juglans regia nuts, has high medicinal value and thus offers many health benefits. No wonder “Shen Nong’s Herbal Classic” (Shen Nong Ben Cao Jing) listed it as the top grade tonic of prolonging life, slimming body, and tonifying qi. Else, generations of physicians viewed it as one of top herbs that could cure a variety of diseases. Among the medical books, “Compendium of Materia Medica” (Ben Cao Gang Mu) said it could tonify Qi and nourish blood; Yu Yao Yuan Fang (Prescription from Emperor Medical Institute) commented it could replenish the blood and complement marrow; Kai Bao Ben Cao (Materia Medica In Kai-Bao Reign) claimed it could makes a man healthy, moisturize skin, and darken hair. Now juglans regia extract, shell powder, extract, oil, tincture, etc. are widely used in homeopathy remedy. Of course, modern medicine has different view and here is the pharmacology about walnut.
Modern pharmacological actions of walnut
1. Its oil can increase body weight and serum albumin while keeping low blood cholesterol levels;
2. It has direct inhibitory and anti-inflammatory effects;
3. Its active ingredient has inhibition on S37 tumor and some certain inhibition on a variety of tumors, such as esophageal cancer, gastric cancer, nasopharyngeal cancer, lung cancer, thyroid cancer, lymphosarcoma, etc. in mice. And it can enhance white blood cell count and protect the liver in cancer patients;
4. It contains many protein and essential unsaturated fatty acids to human body. These are important ingredients of brain histocyte metabolism and can nourish brain cells and enhance brain function;
5. It reduces the intestinal absorption of cholesterol, dissolves the cholesterol, excludes the “dirt impurity” from vascular wall, and thus purifies the blood and provides better blood. As a result, it prevents atherosclerosis and lower cholesterol. In addition, walnuts can also be used to treat non-insulin-dependent diabetes mellitus;
6. It contains a lot of vitamin E, regular consumption of it can moisten lung, reverse gray hair, and improve hair color;
7. It can relieve fatigue and combat stress;
8. It can moisten dryness and lubricate intestines. So it is frequently used for constipation;
9. It also has antitussive effect, which was confirmed by animal experiments.
Proven walnut herbal remedies
Chinese Pharmacopoeia says that walnut is sweet in flavor and warm in properties and it enters three meridians of kidney, lung, and large intestine. Basic functions include nourishing the kidney, warming the lung, and moistening intestines. Chief Juglans regia uses and indications are limp lower back and knees, ED (erectile dysfunction), nocturnal emission, deficiency-cold type dyspnea and cough, and constipation. Recommended dosage is from 6 to 9 grams in decoction, powder, or pills.
1. Qing E Wan. From Tai Ping Hui Min He Ji Ju Fang (Prescriptions from the Taiping Benevolent Pharmaceutical Bureau), this formula is mainly used for soreness of lower back due to kidney deficiency, dizziness, tinnitus, and urine endless. Other main herbal ingredients are Du Zhong (Eucommia Bark), Bu Gu Zhi (Psoralea Fruit), Garlic, and so on.
2. Hu Tao Tang. From Yu Yuan Yao Fang (Prescriptions from Royal Drug Museum), it is normally formulated for waist and knee pain caused by kidney deficiency and powerless feet. Other key herbs are Eucommia Bark, Psoralea Fruit, Bei Xie (Dioscorea Root), and more.
3. Ren Shen Hu Tao Tang. From Ji sheng fang (Formulas to Aid the Living), this recipe combines Hu Tao Ren together with Ren Shen (Ginseng) and Sheng Jiang (Fresh Ginger Rhizome) to treat dyspnea of deficiency type due to lung and kidney deficiency and deficiency of kidney qi failing to control respiring qi.
4. Hu Tao Wan. From San Yin Fang (Three Causes Formulas), it is basically used for consumptive thirst or diabetes, dry mouth and lips, emission, and so on. Other herbs are Fu Ling (Poria), Fu Zi (Prepared Aconite Root), Fresh Ginger, and Ge Fen (mactra clam shell powder).
Juglans regia side effects and contraindications
According to Traditional Chinese medicine (TCM), juglans regia nuts are inadvisable to be taken in the case of fire excess from yin deficiency, sputum and heat cough, and loose stools. In addition, walnut is reported that the alpha-linolenic acid contained may closely associate with prostate cancer.