Rehmannia root, a medicinal material that occupies an important position in the history of Chinese medicine, was first recorded in the "Ben Jing". The rhizome of Rehmannia root is its main medicinal part, especially the Rehmannia root produced in Huaiqing, Henan Province is the most famous. Every autumn or early winter, local farmers will dig up Rehmannia root, remove the residual stems, hairy roots and soil, and then dry it with a slow fire or sun dry. This traditional processing method ensures that the medicinal effect of Rehmannia root is retained to the greatest extent.
Plant characteristics of Rehmannia glutinosa
Rehmannia glutinosa is a perennial herbaceous plant belonging to the Scrophulariaceae family. Its scientific name is Rehmannia glutinosa Libosch. The plant appearance of Rehmannia glutinosa is unique. Its rhizome is irregular and round-shaped thick slices with a brown-black or brown-gray surface. The texture is relatively soft and tough, not easy to break, shiny and sticky. Fresh Rehmannia glutinosa is freshly used rhizome of Rehmannia glutinosa, while raw Rehmannia glutinosa is a product that is slowly baked until it is about 80% dry.
Rehmannia root stems belong to the perennial herb Rehmannia root stems. Fresh Rehmannia root stems are yellow when dug out, hence the name Rehmannia root. Rehmannia root likes places with good sunlight and loose, fertile sandy soil. It is afraid of both drought and waterlogging. The ancients described Rehmannia root as "like a greedy wolf" . This is because the soil of the general planting land will lose its fertility after one year of planting. It will take about 5 to 10 years for the land to slowly become fertile.
Therefore, Rehmannia root cannot be planted continuously. If you plant it this year, you should change it to another crop next year. Probably because of this reason, one of its nicknames is "earth marrow" , which means marrow. It can be seen that Rehmannia root can absorb the essence of the earth.
Indications and efficacy of raw Rehmannia root
Shengdihuang is cold in nature, sweet in taste, and enters the heart, liver, and kidney meridians. Its main function is to clear away heat and cool blood, nourish yin and produce body fluid. Therefore, Shengdihuang is often used to treat symptoms such as heat entering the blood, toxic spots caused by warmness, vomiting blood and bleeding from the nose, yin damage caused by fever, tongue-twisting and thirst, constipation caused by body fluid damage, fever caused by yin deficiency, bone steaming and fatigue fever, and internal heat and thirst.
These properties of raw Rehmannia make it effective in clearing away heat and detoxifying, nourishing yin and promoting the production of body fluid. It is particularly suitable for those blood heat symptoms caused by the invasion of heat evil, such as persistent high fever, skin rashes, bleeding, etc.
In addition, raw Rehmannia root can effectively relieve problems such as thirst, constipation, and internal heat and thirst caused by Yin deficiency. It also has a certain improvement effect on the common Yin deficiency symptoms caused by high stress and staying up late in modern life.
Rehmannia root also has cardiotonic, diuretic, blood sugar lowering, and anti-oxidation effects. These effects make it widely used in modern medicine as an adjuvant treatment for chronic diseases such as cardiovascular disease and diabetes. Rehmannia root extract can also promote blood coagulation, protect the liver, prevent liver glycogen reduction, and has certain anti-radiation damage and anti-fungal effects, which makes it of great value in the prevention and treatment of many diseases.
Indications and efficacy of Rehmannia glutinosa
Rehmannia glutinosa is a processed product of raw rehmannia root. It is slightly warm in nature, sweet in taste, and enters the liver and kidney meridians. Its main function is to nourish blood and yin, and replenish essence and marrow. Rehmannia glutinosa is often used to treat symptoms such as blood deficiency, chlorosis, palpitations, irregular menstruation, metrorrhagia, liver and kidney yin deficiency, soreness and weakness of waist and knees, bone steaming and hot flashes, sweating and spermatorrhea, internal heat and thirst, dizziness, tinnitus, and premature graying of hair.
The warming and nourishing properties of Rehmannia glutinosa make it effective in replenishing blood and nourishing yin. It is particularly suitable for various symptoms caused by blood deficiency or kidney deficiency, such as pale complexion, palpitations, insomnia, irregular menstruation, etc. In addition, Rehmannia glutinosa can effectively relieve the problems of soreness of waist and knees, hot flashes and sweating caused by liver and kidney yin deficiency, and it also has a certain improvement effect on the common symptoms of kidney deficiency caused by high stress and staying up late in modern life.
The main effect of Rehmannia glutinosa is to nourish blood and yin and replenish essence and marrow. It can increase peripheral red blood cells by stimulating erythropoietic stem cells, thereby achieving the effect of nourishing blood, and is particularly suitable for treating the symptoms of blood deficiency and chlorosis.
In addition, Rehmannia root has the effects of strengthening the heart, diuresis, lowering blood sugar, and anti-oxidation. These effects make it widely used in modern medicine as an auxiliary treatment for chronic diseases such as cardiovascular disease and diabetes. The extract of Rehmannia root can also promote blood coagulation, protect the liver, prevent the reduction of liver glycogen, and has certain anti-radiation damage and anti-fungal effects, which makes it of great value in the prevention and treatment of many diseases.
The difference between raw and cooked Rehmannia root
Rehmannia root can be divided into two types: raw rehmannia root and cooked rehmannia root. Compendium of Materia Medica states: Raw rehmannia root is very cold and can cool the blood, so it is needed by those with hot blood; cooked rehmannia root is slightly warm and can nourish the kidneys, so it is needed by those with weak blood.
Although raw and cooked rehmannia roots come from the same plant, their processing methods and medicinal properties are significantly different. Raw rehmannia roots are made by slowly baking fresh rehmannia roots until they are about 80% dry. They are cold in nature, sweet in taste, and enter the heart, liver, and kidney meridians. Cooked rehmannia roots are made by further steaming raw rehmannia roots. They are slightly warm in nature, sweet in taste, and enter the liver and kidney meridians. This processing process not only changes their nature and taste, but also their pharmacological effects.
Raw Rehmannia root is mainly used to clear away heat and cool blood, while cooked Rehmannia root is mainly used to replenish blood and nourish yin.
Raw Rehmannia root is cold in nature and has the effects of clearing away heat, cooling blood, nourishing yin and promoting body fluid, so it is particularly suitable for those blood heat symptoms caused by the invasion of heat evil, such as persistent high fever, skin rashes, bleeding, etc. In addition, raw Rehmannia root can also effectively relieve problems such as thirst, constipation and internal heat caused by yin deficiency, and it also has a certain improvement effect on the common yin deficiency symptoms caused by high stress and staying up late in modern life.
Rehmannia root is slightly warm in nature and has the effects of nourishing blood and yin, replenishing essence and filling marrow. Therefore, it is often used to treat symptoms such as blood deficiency and chlorosis, palpitations, irregular menstruation, metrorrhagia, liver and kidney yin deficiency, soreness of the waist and knees, bone steaming and hot flashes, sweating and spermatorrhea, internal heat and thirst, dizziness, tinnitus, and premature graying of hair.
It is particularly suitable for various symptoms caused by blood deficiency or kidney deficiency, such as pale complexion, palpitations, insomnia, irregular menstruation, etc. In addition, Rehmannia glutinosa can effectively relieve the problems of soreness of waist and knees, hot flashes, sweating and spermatorrhea caused by liver and kidney yin deficiency, and it also has a certain improvement effect on the common symptoms of kidney deficiency caused by high pressure and staying up late in modern life.
The warming and nourishing properties of Rehmannia glutinosa make it significantly effective in replenishing blood and nourishing yin, and it is particularly suitable for long-term conditioning and nourishing.
Modern Applications of Rehmannia glutinosa
Modern medical research shows that Rehmannia contains a variety of ingredients, including catalpol, β-sitosterol, mannitol, rehmannia root, vitamin A substances, and rehmannia picroside. These ingredients change during different processing processes, thus affecting the efficacy of Rehmannia root. For example, the catalpol content in raw Rehmannia root is higher, while the catalpol content in cooked Rehmannia root is decomposed during the processing process and converted into other ingredients.
There are many ways to prepare Rehmannia root, and their functions are to change the medicinal properties and improve the efficacy . After steaming and ripening Rehmannia root, the medicinal properties change from cold to warm, the taste changes from bitter to sweet, and the function changes from clearing to nourishing.
Chen Cangqi's "Compendium of Materia Medica" says: "Compendium of Materia Medica mentions dried Rehmannia root, but the Classic of Materia Medica does not mention raw dried or steamed dried. Today, the two are used by prescriptionists separately. Steamed dried is warming and nourishing, while raw dried is mild and detoxifying. They should be used accordingly." This shows that medical scientists before the Tang Dynasty had already mastered the method of steaming raw Rehmannia root into cooked Rehmannia root.
There are many different methods for processing Rehmannia root in modern times. The traditional methods of "nine processing (nine steaming and nine drying)", "wine processing" or "long processing" have been simplified to "one processing (one steaming and one drying)" or "three processing (three steaming and three drying)" in modern times. These changes not only affect the ingredients of Rehmannia root, but also its medicinal effects.
Modern research has also found that after processing, some polysaccharides and oligosaccharides will be hydrolyzed and converted into monosaccharides, and the monosaccharide content in cooked rehmannia is more than twice that in raw rehmannia . In addition, processing will also decompose terpenoid glycosides and reduce amino acid content, but the changes in trace elements and dissolution rate are not significant.
Notes
When using Rehmannia root, you need to pay attention to its processing method and ingredient changes. The commercially available "cooked Rehmannia root" sometimes adds other substances to increase its black color or sweetness, which may affect its efficacy. Therefore, when choosing Rehmannia root, you should prepare it according to the "Chinese Pharmacopoeia" to ensure its quality and efficacy.
In addition, the blood-tonifying effect of Rehmannia glutinosa is mainly achieved by stimulating hematopoietic progenitor cells and hematopoietic stem cells. Therefore, when using it, the appropriate processing method should be selected according to the specific symptoms.
Conclusion
As traditional Chinese medicines, raw and cooked rehmannia root have a rich historical background and diverse pharmacological effects. They have significant effects in clearing away heat and detoxifying, nourishing yin and promoting body fluid, and replenishing blood and yin.
Modern medical research has further revealed the effects of Rehmannia root ingredients and processing methods on its efficacy, providing a scientific basis for its application in modern medicine. Whether it is the traditional "nine processing" method or the modern simplified processing, the efficacy of Rehmannia root remains the same, providing an important guarantee for people's health.