Du Zhong - Eucommia bark
Du Zhong is the bark of the Eucommia tree and one of the most important remedies for strengthening Tendons, bones and the lower back. It is traditionally used to treat kidney weakness in the lower back and to support a healthy pregnancy.
When the bark is broken, characteristic silvery gutta-percha threads appear - an unmistakable distinguishing feature that also serves as a Quality indicator serves.
Effect from a TCM perspective
Du Zhong tonifies the liver and kidneys and strengthens the tendons and bones—especially in cases of weakness in the lower back and knees. It warms kidney yang and is traditionally used to calm a restless fetus (Tāi Dòng Bù Ān).
- Tones the liver and kidneys and strengthens tendons and bones in cases of lower back weakness
- Warms the kidney yang with frequent, clear urination and a cold back
- Calms the fetus and helps prevent miscarriage (Ān Tāi) when there is a risk of miscarriage
- Lowers rising liver yang for liver and kidney yin deficiency
- Strengthens bone structure and promotes bone formation in cases of fractures
Application & dosage
Du Zhong is usually prepared as a decoction. The salt-roasted form (Yán Dù Zhòng) specifically enhances kidney function and is the treatment of choice for weakness and cold in the lower back, as well as kidney yang deficiency.
The dosage depends on the pattern—if there is significant weakness in the lower back, the dose can be set at the higher end of the range; if the goal is to ensure a successful pregnancy, it should be set toward the middle of the range.
Dosage forms
- Decoction (Cook for 15–20 min.) — Standard preparation
- Salt-roasted (Yán Dù Zhòng) — enhanced kidney function
- Granules — easy to take, 3–5 g daily
- Tablets — 3–4 tablets, 500 mg each, 2–3 times a day
- Powder — 3–5 g daily, in warm water or wine
Dosage
- Decoct: 10-15 g
- Granules: 3–5 g daily
- Powder: 3–5 g daily
- Tablets: 1.5–2 g daily
Frequent combination partners
Du Zhong often only unfolds its full effect in combination with other herbs
History & Tradition
Du Zhong is described in the *Shennong Bencao Jing* as the herb of the upper class recorded — an indication that it was considered nontoxic and suitable for long-term use. According to legend, it was named after a Daoist immortal named Dù Zhòng, who is said to have discovered the plant and passed on its secrets to humankind.
The Eucommia tree is a living fossil — It is the sole surviving member of its family (Eucommiaceae) and has existed since the Tertiary Period. The genus was once widespread throughout the Northern Hemisphere; today, only a single species survives in the mountain forests of central China.
Táo Hóngjǐng (456–536) praised Du Zhong as the most important remedy for strengthening the lower back. The tradition of roasting the bark with salt to enhance its effect on the kidneys dates back to the Song Dynasty and continues to this day in TCM practice.
In modern TCM, Du Zhong has gained particular significance in orthopedics and gynecology—as a support for the musculoskeletal system and as a gentle support during pregnancy.
Contraindications & caution
- Not at Yin Deficiency with Severe Heat without Yang deficiency — the warming nature of Du Zhong can intensify the heat.
- Be cautious if you experience a dry mouth and night sweats as signs of Yin–Emptiness–Heat — In this case, cooling Yin tonics such as Zhi Mu should also be combined.
- At Fullness and Heat in the Liver Region Zhong is not suitable for you, as it tonifies the liver instead of clearing heat.
- When taken at the same time as Blood Pressure Medications Consultation with a doctor is recommended.
Botany
Eucommia ulmoides Oliv. is a deciduous tree belonging to the monotypic Eucommiaceae family, which reaches heights of 10–20 m. The leaves are elliptical, serrated, and vaguely resemble elm leaves—hence the species name ulmoides. The plant is dioecious; male trees form catkins, female winged nut fruits.
The most striking feature is the Bark containing gutta-percha: When broken, silvery-white latex strands stretch between the fragments. This characteristic serves as reliable proof of authenticity and an indicator of quality. The leaves and seeds also contain gutta-percha, albeit in lower concentrations.
Occurrence
- Natural Distribution in the mountain forests of central China—particularly in Sichuan, Guizhou, and Hubei
- Prefers moist, deep soils at altitudes of 300-1500 m
- The sole surviving member of the Eucommiaceae family — a living fossil
- Now also grown commercially in Japan and Korea
- Largest Growing Regions in Zhangjiajie (Hunan) and Zunyi (Guizhou)
Harvest time
- Bark is produced by April through June harvested — during peak sap flow
- Only from trees 15–20 years Age — younger bark contains fewer nutrients
- Harvesting method: Strips of bark are peeled off; the tree regenerates the bark in 5–8 years
- Sustainable harvesting possible without felling the tree
Processing
After harvesting, the fresh bark is first stacked and allowed to ferment slightly until the inner surface turns a purplish-brown color. It is then dried and processed for pharmaceutical use.
- Raw bark (Shēng Dù Zhòng)
Dried and cut into pieces - standard processing for general use
- Salt-roasted (Yán Dù Zhòng)
- Spray pieces of bark with salt water
- Toast in the pan over a medium heat until the gutta-percha threads break off when you break them
- Allow to cool - the salt-roasted form directs the effect specifically to the kidneys
Related herbs
Herbs with similar effects and related areas of application