According to Chinese medicine, the key to good health is maintaining balance between the two opposing forces that exist within our body, Yin and Yang. The herb rehmannia – also called di huang (yellow earth) in Chinese – is said to “balance the Yin” and even “quiet the Soul.” First mentioned in Chinese medical literature during the Han Dynasty (200 B.C.) with a wide and varied list of benefits, this root remains prominent more than two thousand years later. Classified as a longevity tonic, rehmannia supports the brain, heart, nervous, endocrine and immune systems. It is also said to ‘cool down internal heat’ and help reduce inflammation as well as blood pressure. From earliest times, rehmannia has been deemed an herb of restoration – repairing broken bones, severed sinews, debilitated bone marrow, wasted muscles and damaged flesh. Formulas addressing chronic fatigue, diabetes, “tired blood” (anemia), fever and weakened bones (osteoporosis) all rely on rehmannia as a chief herb. In modern times, rehmannia has also become the go-to herb for hormonal imbalances associated with menopause and infertility, thyroid imbalance and adrenal insufficiency.
The thick black roots of rehmannia provide a remarkable reservoir of nutrients that benefit the kidneys, liver and blood. In Chinese medical theory, the kidneys are considered to be the flame of life. Pain and weakness in the lower back and knees, hearing loss and premature aging are all are common manifestations of kidney deficiency. Because rehmannia helps restore adrenal function and strengthen the kidneys, it is one of the premier tonic herbs used to treat these conditions and provide anti-aging support. Studies have shown that rehmannia helps to enhance the cells of the pituitary gland and adrenal cortex during times of stress, as well as combat adrenal suppression caused by steroid hormones. For those with impaired liver function, rehmannia can help to improve blood flow to the organ and strengthen its function. Indeed, it is one of the few herbs found to effectively help treat hepatitis. Finally, research has demonstrated rehmannia’s ability to lower cholesterol and blood sugar levels.
According to Chinese herbal theory, the primary functions of this root include clearing heat, cooling blood, nourishing Yin, and promoting the production of bodily fluids. More specifically, rehmannia helps to:
Support kidney and adrenal function, vital to energy as well as fertility
Protect and restore liver health, crucial to toxin elimination
Regulate hormone imbalance
Cool the body, clearing heat associated with fevers, hot flashes and night sweats
Reduce inflammation, addressing issues such as asthma and skin diseases
Improve cognitive performance and brain health
Nourish proper blood formation, aiding conditions such as anemia
Promote the production of body fluids and marrow
Support normal function of the entire reproductive system
MODERN DAY APPLICATION & UNDERSTANDING OF REHMANNIA
Despite its ancient origins and applications, rehmannia is one of a small group of herbs being used today to successfully combat the symptoms and progression of chronic and consumptive diseases – including many autoimmune diseases. Indeed, Yin deficiency is a common presentation among immune disorders such as SLE, Sjogren’s syndrome, rheumatoid arthritis, multiple sclerosis, psoriasis, eczema and fibromyalgia. Other modern-day chronic diseases such as hypertension, diabetes, hepatitis and asthma also benefit greatly from the heat-clearing, fluid-generating and blood-tonifying powers of rehmannia.
In one study, patients suffering with rheumatoid arthritis who were treated with rehmannia experienced reduced joint pain and swelling, as well as increased joint movement due to its anti-inflammatory properties. For inflammation of the gut, research has found that rehmannia can also help soothe the intestinal wall (with a mild laxative action). Lastly, rehmannia has been found to combat chronic fatigue syndrome (associated with adrenal fatigue) and blood sugar imbalance.
Because of its ability to enrich Yin and blood, rehmannia is an especially effective medicinal herb to support female fertility. It is one of the most effective herbs available today to help regulate a woman’s hormone balance and menstrual cycle. In addition to promoting regular menstrual cycles, rehmannia can help curb mid-cycle bleeding, as well as excessive bleeding in women with menorrhagia. Rehmannia is also widely used to help support women throughout menopause, relieving hot flashes and night sweats, as well as combatting bone loss. Indeed, the root is a great supplement for women who seek relief from some of the most bothersome symptoms of menopause, but want to avoid the dangers of hormone replacement therapy.
Scientists believe that the primary constituents of rehmannia – called iridoid glycosides – stimulate production of adrenal cortical hormones. Importantly, these hormones have anti-inflammatory action (explaining rehmannia’s benefits for asthma, skin diseases, and arthritis) in addition to their involvement in the production of sex hormones (explaining their benefit of treating menopause, impotence, and other signs of hormone deficiency). It is likely that the root’s anti-inflammatory effects at least partly explain its classical use in mending bones and healing injuries.
RAW VS PREPARED REHMANNIA
While rehmannia has been consistently used for centuries, not all rehmannia is the same. Today, there are commonly two types of herbs found in the Chinese herbalist’s apothecary derived from the di huang root. While both are capable of treating conditions caused by the deficiency of Yin and/or body fluids, clinically they are classified as different herbs within the materia medica, each possessing their own unique characteristics and healing properties.
Raw or dried rehmannia root – known as sheng di huang in Chinese – consists of freshly harvested roots that are slowly baked until nearly dry (in the sun or an oven) and then kneaded into round balls. Prepared rehmannia root – called shu di huang – refers to dried roots that have been further cooked/steamed in rice wine and then re-dried, often repeatedly, until they become black, oily, soft and sticky. Compared to raw or dried rehmannia (sheng di), the tonic properties of the prepared root (shu di) are greatly enhanced by processing.
Raw or dried rehmannia (sheng di) has a sweet taste and cold-moist nature – in its unprocessed form, this type of rehmannia excels at clearing heat and cooling blood. Additional actions of sheng di include stopping bleeding and nourishing Yin (especially when Yin has been injured due to heat).
With the additional processing, prepared rehmannia (shu di) becomes slightly warm in nature, impeding its power to purge fire or cool blood, but gaining in ability to nourish Yin and blood. Prepared rehmannia (shu di) is an important liver-kidney tonic that nourishes Yin, replenishes blood, and reinforces essence (marrow). Traditional Chinese medicine believes that essence and blood are the most fundamental material basis of the body. A vacuity of blood and essence can result in light-headedness, sore aching low back and knees, deafness, tinnitus, anemia, premature graying and/or aging and sexual dysfunction. Processed rehmannia root (shu di) is commonly used to treat women’s reproductive conditions where blood deficiency can lead to scanty menses, irregular periods and even fertility issues. Chronic heavy menstrual flow can also lead to blood and Yin deficiencies. Yin deficiency associated with menopause typically manifests with hot flushes, night sweats, lumbar soreness, throat dryness, thirst, a red tongue tip and rapid, thread pulse. Growth retardation in children, as well as premature gray hair, weak bones and poor dental health are also associated with essence and marrow insufficiency.
REHMANNIA-BASED HERBAL FORMULAS
In both its raw and processed forms, rehmannia is a core ingredient in many of the most important Chinese herbal remedies designed to tonify the fundamental substances within the body and help restore health and wellness. A few of the most widely known and used for the last several centuries include:
Si Wu Tang
Si Wu Tang is a classic blood tonic often used to help regulate menstruation. From the perspective of Chinese medicine, general signs of blood deficiency include dry skin, pale complexion, insomnia, irregular menstrual cycles with scanty flow, dizziness, vertigo, constipation and/or fatigue. Blood deficiency is particularly common in women due to the loss of menstrual blood (as well as vegetarians who are not careful to get enough protein in their diets). Si Wi Tang addresses blood deficiency, with emphasis on liver blood (in Chinese medicine, the liver is responsible for maintaining a normal menstrual cycle). Si Wu Tang is particularly suited to cases of chronic blood deficiency with menstrual irregularities, which can lead to infertility. The formula also helps to regulate the Chong Mai and Ren Mai, major meridians associated with fertility. With the appropriate presentation, Si Wu Tang is also used to treat conditions such as anemia, menorrhagia, postpartum fatigue / weakness, threatened miscarriage, insufficient lactation, and generalized muscle tension.
Si Wu Tang is an elegant, well-balanced blood tonic composed of just four Chinese herbs. These herbs fall into two groups, based on the role they play in the formula. The first group, consisting of shu di huang (rehmannia preparata) and bai shao (peony), both tonify the blood. The second group of herbs, consisting of dang gui (angelica) and chuan xiong (lovage), invigorate blood to dispel and prevent blood stasis, which often develops in the context of chronic blood deficiency.
Even though Si Wu Tang is regarded as one of Chinese medicine’s most widely used blood tonics, it is rarely used by itself in actual practice. Instead, it tends function as a 'base' formula that is often combined with other, additional herbs to build more complex formulas. For instance, when patients also have Qi / vital energy deficiency that includes lethargy, mental fatigue and general weakness in addition to blood vacuity (which often happens after an illness when it becomes difficult to bounce back and fully regain your strength), four additional herbs will be added to make Ba Zhen Tang to replenish both blood and Qi.
Liu Wei Di Huang Wan
Liu Wei Di Huang Wan is one of the most famous and frequently used formulas in traditional Chinese medicine. Originally developed in the Song dynasty, this formula is widely prescribed to nourish the Yin. In addition to delivering very effective relief of menopausal symptoms, it is also frequently used in the treatment of diabetes, hypertension and disorders of the immune system.
Liu Wei Di Huang Wan is comprised of three pairs of herbs, with each duo incorporating an herb that gently tonifies and drains (or disperses) a particular zang-fu organ. For instance:
shu di huang (rehmanniae preparata) warms, enriches yin, and nourishes the kidney, while ze xie (alisma) cools, reduces dampness, and drains moisture in the kidney
shan zhu yu (cornus) warms and nourishes the liver, while mu dan pi (moutan) clears liver fire and moves liver blood
shan yao (dioscorea) warms and strengthens the spleen, while fu ling (poria) resolves spleen dampness
Each pair within the formula acts to balance their tonifiying and dispersing actions on the organs. Together, shan yao and fu ling improve the function of the spleen, thereby enhancing the extraction of nutrients from food and nourishing the blood (as well as improving liver function). Likewise, shan zhu yu and mu dan pi enriched the blood and improve liver function (which in turn provides moistening action to the kidney). Finally, shu di huang and ze xie restore kidney Yin and essence, as well as normalize kidney functions.
While Liu Wei Di Huang Wan often serves as a stand-alone remedy, like Si Wu Tang it is also used as a base formula, modified with the addition of extra herbs to make more complex or targeted formulas. For instance, when the two kidney-warming herbs rou gui (cinnamon) and fu zi (aconite) are added, it becomes Jin Qui Shen Qi Wan, a famous formula that tonifies both Kidney Yin and Yang – often prescribed to older patients suffering from degenerative conditions marked by the presence of a urinary disorder.
Da Bu Yin Wan
Da Bu Yin Wan works to restore and maintain the balance between Yin and Yang that is often disrupted as we age. It’s a potent Yin tonic that was developed more than 700 years ago to extinguish pathogenic fire that often flares up within the body due to Yin deficiency. The formula combines shu di huang (rehmannia preparata) and gui ban (turtle shell) – two potent Yin tonics – with zhi mu (anemarrhena) and huang bai (phellodendri) to clear heat that often manifests as night sweats, hot flashes and steaming bone syndrome, among other symptoms.
Jiao Ai Tang
This classic formula is designed to nourish the blood, stop bleeding, and regulate menstruation while quieting / calming the fetus. Jiao Ai Tang is often prescribed for conditions that are characterized by abdominal pain, uterine bleeding, spotting during menstrual cycle, post-partum bleeding, bleeding during pregnancy, and general weakness and fatigue. It is best suited for conditions characterized by a deficiency of the Chong and Ren Mai, which are directly connected to the sea of blood, the womb and fetus.
Within this formula, e jiao (corri asini) is the sovereign medicinal which nourishes the blood and stops bleeding, while ai ye (artemisa) warms and quiets the uterus, and stops bleeding. Shu di huang (rehmannia preparata), along with dang gui (angelica), bai shao (peony), and chuan xiong (lovage) are all included to supplement the blood and regulate menstruation. Interestingly, this formula is essentially Si Wu Tang with a few additional herbs. Sometimes, sheng di huang is substituted for shu di huang to help quicken the blood and dispel stasis that may be either causing – or caused by – the bleeding.
THE CLOYING NATURE OF REHMANNIA
One of rehmannia’s most prominent features is its “cloying” nature, which can be thought of as “supplying too much of something, especially something too rich or sweet.” The word is also short for the obsolete term accloy, which means to clog or satiate. Others describe the nature of rehmannia as “sticky” or “heavy.” The root, especially the processed / steamed (shu di) variety is dense, sticky and sweet. When taken in large doses, it can be hard to digest. According to Chinese medicine, rehmannia’s physical properties of density and stickiness reflect its function within the body: to settle erratic Qi that is uncontrolled by the kidney (and liver). Its heaviness helps it draw Qi downward to the lower burner so that it can then rise in a more orderly fashion, along its intended pathways (meridians). The stickiness also helps it draw scattered Qi together so that it sticks to its intended pathways.
The dosage for rehmannia root is wide-ranging depending on the preparation used and is best discussed with your doctor of Chinese medicine. While the usual dosage is 10 – 15g, it could easily be increased to 30g depending upon the circumstances and condition being treated. Because of its cloying nature, care must be taken to make sure that rehmannia doesn’t disturb the body’s digestion and absorption process and should be used with caution by patients with stomach deficiencies. Likewise, rehmannia is not suitable for pregnant or breastfeeding women.