Rehmannia (botanical name, Rehmannia glutinosa) is a perennial herb having a straight stem and growing up to a height of 60 cm. The plant also has a basal rosette of jagged or tooth-like margined leaves growing on the stem. The plant bears purplish-orange hued flowers that are cymose (an inflorescence wherein the main axis bears a solitary flower in the middle or at the terminal that blooms first). Rehmannia has a large rhizome which is succulent and has a brownish-yellow color. When this rhizome is prepared its color changes to tar-like black and it becomes supple as well as soft. The prepared rhizome is available in the form of slices or smaller pieces. It has a somewhat sweet flavor.
Investigational as well as clinical substantiation indicate that rehmannia rhizome possesses an anti-hepatotoxic (liver detoxifying) action as well as a latent outcome in a number of cases of hepatitis. In addition, clinical work with this herb also hints that it also possesses anti-rheumatic and anti-eczema properties. Some researches have also identified that the rhizome has hypoglycemic (an exceptionally low glucose level in the bloodstream) effects. Clinical trials have demonstrated that the medication prepared with the rehmannia rhizome helps to lower blood pressure as well as cholesterol levels.
Traditional Chinese Medicine has used this herb extensively. While there is lack of methodical clinical trials, Chinese herbalists have used rehmannia to cure an assortment of health conditions, such as asthma, arthritis, chronic nephritis (inflammation of the kidneys) and urticaria (hives) in their researches. In addition, it has been found that rehmannia is also a useful herb in preventing the suppressive consequences of corticosteroid (steroid) drugs.
It may be mentioned that rehmannia has shown potentials of being an effective herbal remedy for aplastic anemia (an acute case of anemia owing to obliteration or inhibited functioning of the bone marrow, generally caused due to bone cancer, radiation or the noxious consequences of some drugs or chemicals), healing obdurate eczema or dry skin, alleviating the adverse side effects of chemotherapeutic agents as well as HIV medications, providing relief from pain in lung or bone cancer or disc protrusion, facilitating in the improvement of health conditions like lupus, nephritis or inflammation of the kidneys and type 2 diabetes accompanied by high cholesterol levels in bloodstream (hyperlipidemia). Nevertheless, as of now, there is no superior-grade, controlled experiments that support the usefulness of rehmannia in treating any of the conditions mentioned above.
Although rehmannia has been included in the Pharmacopoeia of the People's Republic of China, it does not find a place in the United Kingdom's General Sale List and is neither included in a Commission E monograph in Germany. On the other hand, the Food and Drug Administration (FDA) of the United States has not granted rehmannia the status of generalized recognized as safe (GRAS). However, as per the stipulations of the Dietary Supplement Health and Education Act of 1994, rehmannia is still offered in the United States in the form of a dietary supplement.
The rhizome or root.
Rehmannia may be used both fresh and dried, especially as a remedy for ‘heat' problems accompanied with depletion of the yin (negative, dark, and feminine, according to Chinese philosophy) energies, for instance, jing or xue, which results in symptoms, such as fever, scarlet tongue (also known as scarlet fever with white coating on the tongue), blood in the sputum or nasal discharge, signs of internal deficiency, exanthemata (a skin eruption owing to viral infection), throat infections and other infections. In addition, traditionally diabetes was also treated with rehmannia, but it was possibly just a limited reason.
Rehmannia also has actions that tone up with a greater application for damages caused to the yin due to heat and they are accompanied by symptoms like high temperature (persistent pyrexia), dry mouth as well as constipation. In addition, rehmannia also has a cooling application to ‘heat' in the heart, a condition accompanied by symptoms like insomnia, ulcers in the mouth, irritability and malar flush (a condition wherein the cheekbones have a high color with a bluish tinge as a result of lessened concentration of oxygen in the blood and usually followed by rheumatic fever).
Rehmannia, prepared by cooking the plant's rhizome in wine, has always been a very popular herbal remedy and is still preferred by many today. This herbal preparation is considered to be an important tonic or stimulating remedy and is helpful in reinstating any type of deficiency of the yin or xue. Rehmannia is especially effective in treating problems owing to yin deficiency in the kidneys which is accompanied by symptoms like nocturnal emissions and night sweats. It is also helpful in curing xue deficiency, for instance in cases like palpitations, vertigo, insomnia and pallor (extreme or exceptional paleness due to ill health). Rehmannia is especially beneficial for women as it is effective in treating symptoms like erratic menstruation, menorrhagia (excessive menstrual discharge) and post-partum hemorrhage (profuse bleeding after childbirth).
In addition, the herbal preparation of rehmannia is also responsible for regeneration of red blood cells. It is believed that this remedy may also have anti-tumour actions, denoting that it prevents and treats tumours. In addition, rehmannia is prescribed by herbal medicine practitioners to boost up the energy and sexuality. Many are of the view that this herbal remedy may also be useful in controlling the blood sugar levels. Herbalists in China have been using rehmannia to cure certain health problems, including those related to the kidneys.
Chemical analysis of the rehmannia roots (rhizomes) has shown that it encloses amino acids, vitamins A, B and C, rehmaglitin, cerebroside, melittoside, dammelittoside as well as other elements which possess anti-inflammatory and anti-fungal attributes. Rehmannia aids in putting off glycogen exhaustion in patients suffering from hypoglycemia (exceptionally low glucose level in the bloodstream) and, at the same time, facilitates in diffusing the body heat. The astringent compounds enclosed by rehmannia are effective in stopping bleeding from ulcers as well as in lessening the irritation and swelling (inflammation) in the digestive tract. Other compounds present in rehmannia act to lower the vulnerability of capillary tubes (smaller blood vessels) and also assist in protecting the adrenal glands. Moreover, this herb is effective in maintaining the normal functioning of the liver. Rehmannia also tones up the blood and helps in doing away with the deficiencies in blood, thereby working as a tonic for the blood.
Since rehmannia has been traditionally used to help with hemorrhagic bleeding (excessive blood loss from ruptured blood vessels) as well as for spotting between menstrual periods (metrorrhagia), this plant may also be employed to prop up the vigour of a female's reproductive cycle. In addition, rehmannia may especially be helpful at times when these symptoms come along with depression, pre-menstrual exhaustion as well as poor ability to handle trauma.
When women suffer from the above mentioned symptoms, they are usually given rehmannia in combination with rhodiola and withania - both these herbal preparations also facilitate in augmenting the energy levels as well as improve the ability of the body to deal with stress. Apart from being extremely useful to women, these three herbs are also especially prescribed to men who suffer from erectile dysfunction (ET) or problems related to low libido (sexual drive). These herbs are more effective when low libido in men is occurring together with exhaustion or fatigue and stress.
Occasionally, rehmannia is also included in a multi-herbal tonic which acts in synergy to reinforce the normal functioning of all the organs of our body. The other herbs that are usually included to prepare a multi-herbal tonic as discussed here comprise of globe artichoke and ginger (herbs for the digestive system), astragalus and Echinacea (herbs for reinforcing the immune system), Siberian ginseng and gotu kola (herbs to support the nervous system) and ginkgo and hawthorn (herbs for the cardiovascular system).
Generally, rehmannia is widely used in the clinics in the eastern parts of the globe (Orient) where it is known as ‘yellow earth' or di-huang. The primary use of this herb is to regenerate the essential forces as well as to facilitate in treating constipation, diabetes, problems of the urinary tract, dizziness, and anemia as well as in regulating the menstrual flow. It has been found that the use of di-huang has an anti-fungal action and is frequently used for Candida (any parasitic fungus belonging to genus Candida and responsible for diseases like athlete's foot, thrush, vaginitis and other contagions). In addition, di-huang also possesses the aptitude to lessen the intensity of glucose in the bloodstream.
Rehmannia is also effective in lowering blood pressure and enhancing the blood circulation to the brain. It is also known as a blood tonic and, additionally, works as a diuretic. Other uses of rehmannia or di-huang include strengthening the tissues and bones and, at the same time, augmenting fertility and libido. In China, physicians have successfully used rehmannia along with licorice to treat hepatitis. In addition, rehmannia is a useful herb for dispersing body heat and easing symptoms like fevers and night sweats.
In Traditional Chinese Medicine, one of the conventional uses of the herbal preparation of the roots of rehmannia has been treating hearing loss as well as tinnitus (ringing or hissing sensation in the ears). This herb also appears to be effective in foraging the harmful free radicals in vitro (a biological process that is made to happen in a controlled experimental setting or in a laboratory). However, this research does not mention or confirm the effects of using Rehmannia glutinosa in human subjects.
Habitat and cultivation
The perennial herb rehmannia is native to the north-western parts of China as well as Inner Mongolia, where the plant is found growing in the wild.
Chemical analysis of the rehmannia rhizome (R. glutinosa) has revealed that it encloses several elements, including glycosides, phenethyl alcohol, iridoids, sterols, cyclopentanoid monoterpenes, rehmannin, norcarotenoids and mannitol. All these substances have been extracted from the fresh or prepared root of this herb.
Medical preparations using the rehmannia rhizome are generally available in the form of a tonic. If you are using this herbal preparation to prop up the nervous system when you are down by stress and exhaustion, you ought to take 2g of rehmannia every day in combination with other tonics for the nervous system, for instance, licorice, rhodiola and withania.
Then again, you may take a tonic that provides as much as 750 mg of rehmannia daily in conjunction with other different herbs that promote health and energy of the entire body.
Side effects and cautions
Patients taking rehmannia preparations ought to adopt a few precautions. Especially, women should not take this herbal preparation during pregnancy or when they are breast feeding.
People suffering from depression should never depend on rehmannia as the sole remedy for their condition. In such cases it is advisable to talk to your healthcare provider for further information and help.
Rehmannia is often combined with other herbal medications to facilitate treatment of certain health conditions. For instance, herbalists occasionally combine this herb with licorice, which is also conventionally employed as an adrenal stimulant (tonic). While rehmannia and licorice possess analogous properties, different from licorice, rehmannia is considered to be a safe medication for patients who have been enduring high blood pressure (hypertension).