Rehmannia – legendary root of restoration and tonification
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.
Many thanks and gratitude to:
Article written by
Ellen Brown L.Ac. DACM