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The five elements and organs diagram

What is Dual Modulation?

The central tenet of Chinese medical thought is that the whole body should be kept in harmony. The theory of Yin Yang and the Five Elements are two ways of expressing this system harmony. This means that each organ of the body not only must perform well, but also must keep in balance with the rest. When one organ is not functioning, as it should, it will affect the overall performance of the others. TCM seeks to restore the body to a condition of balance using a method called dual modulation.

In pharmacological terms, dual modulation is when a drug (which commonly are herbal prescriptions in TCM) possesses a dual character. This means that when the body is in an unbalanced state, the same drug can be used to cause the body to go from a hyper-functioning to a normal state, or from an under-functioning to a normal state, with no adverse effects. Many Chinese medicines have dual modulation characteristics. TCM has unique theories about this, categorizing the regulating properties of the medicinal substance into eight actions; "ascend and descend", "cold and heat production", "yin and yang", "reinforce and reduce", "excrete/drain and astringent", "dry and moisture", "activate and stop or slow down circulation", and "dissolve and gather". These actions relate to the drug's character and taste, quality, combination, processing methods and administration method.

Four Important Concepts of Dual Modulation

Dual modulation of particular herbs and medicinal substances is possible because of four important concepts. These are:

1. Herbs contain multiple active ingredients, which can have opposite effects on the body.
2. Different amounts of the same herb or medicinal substances can have opposite effects on the body.
3. The body's adaptation ability can allow herbs to work differently in times of stress or illness.
4. Different processing or preparation methods can bring about different healing effects of the same herb or medicinal substance.

1. Herbs contain multiple active ingredients, which can have opposite effects on the body.

A single herb, containing reverse-acting ingredients, forms the elemental basis for dual modulation. Complex formulas consisting of several herbs create a much more complicated mechanism because different active ingredients can work together to produce a more desired health effect, or a particular herbal combination can cancel out the negative effects associated with a single herbal ingredient thereby minimizing side effects and retaining only the desired effect. These complex herbal prescriptions are combined in such a way to make them more flexible in the conditions that they treat. Western medicine simply cannot match the range and scope of Chinese herbal medicine.

Some examples of this concept include:
Huang qi (astragalus)
Huang qi () or astragalus's traditional functions are to invigorate qi (vital energy)), benefit yang and increase body resistance. The main active ingredients identified in this herb are astragaloside and huang chi polysaccharide. Modern research shows that its dual modulation capabilities allow it to regulate the immune system by increasing the immune response when it is suppressed, and depressing the immune response when it is too high or over functioning. Therefore, the action of invigorating qi and benefiting yang can be interpreted in modern medicine as promoting and regulating the body's immune functions; thereby, maintaining the balance of the internal environment.
The root of pseudo-ginseng (san qi TC), according to TCM application, is a drug used to stop bleeding and promote blood flow. The ancient classic the Bencao Gangmu (Compendium of Materia Medica) claims that it can "stop bleeding, dissolve blood stasis, and relieve pain." Pharmacological research has shown that it has a double action on the blood clotting system; active ingredients of pseudo-ginseng like saponin activate blood circulation and dissolve stasis, while san-qi-su stops bleeding. Other psuedo-ginseng active compounds, dencichine and ginseng propanol, also possess opposite blood clotting effects. Dencichine increases the production of certain clotting factors in the liver, and activates them, helping to stop bleeding. Ginseng proponal, on the other hand, increases the cAMP content in platelets, declines the production of TXA2, and prevents thrombosis (a fixed blood clot in the body). Although the body can modulate its own coagulation-anticoagulation system, pseudo-ginseng improves this action by its ability to both stimulate and prevent blood clotting with its active ingredients.

2. Different amounts of the same herb or medicinal substances can have opposite effects on the body.

When using single herbs or complex formulas, different quantities will produce different health effects. For example:

Ginseng (H) is a well-known tonic for invigorating primordial energy, and its main ingredient is ginsenoside. Studies show that small dosages causes high blood pressure in dogs and increase the strength of heart contractions. Large dosages cause transitional hypotension (low blood pressure), decrease the strength of heart contractions and lower the heart rate.
The usual dosage of rhubarb (da huang j) is 9g-15g; its main effect is diarrhea, which is caused by the active ingredient, quinone. However, when rhubarb is used in small dosages (e.g. around 1g), it will benefit the stomach and stop diarrhea. This illustrates that, by using different dosages, the ratio of active ingredients that work for dual modulation may change, resulting in different effects.
According to some studies, dosages of astragalus (huang chi ) below 20g can lead to noticeable diuresis (excessive urination). However when dosages over 30g are used, it inhibits urination.

3. The body's adaptation mechanism can be enhanced with TCM medicinal substances

Recent studies show that certain Chinese herbs such as ginseng (H), acanthopanax (뤭[), rhodiolae root () and Ganoderma lucidum (F), can improve non-specific resistance to negative influences when the body encounters harmful stimulation. This is due to the drug's enhancement of the body's own "adaptation" mechanism. This kind of non-specific resistance only works in special circumstances, such as when the body's immune resistance is low, under stress or when it has to do extra work. When the body is in normal health, therapeutic dosages of these herbs do not interfere with physiological functions or cause any adverse effects. Russian cosmonauts carried these kinds of Chinese medicines with them as health supplements during their voyage into space.

Acanthopanax Barbary wolfberry fruit Ganoderma lucidum

4. Different processing or preparation methods can bring about different healing effects of the same herb or medicinal substance.

Different therapeutic effects are achieved with different processing methods. For example:

Rhubarb (da huang j): leads to severe diarrhea when used fresh, moderate diarrhea when processed; it can also stop bleeding after being fried. This is due to the heat that decomposes the active ingredient, quinone.
Fleece flower root
Fleece flower root (he shou wu 󭺯Q): possesses lubricant and diarrhea effects when it is used fresh. When processed, it benefits the liver and kidneys, replenishing the essence (jing) and the marrow. This is also due to the decomposition of the active ingredient, quinone.

Formula Prescription

By understanding the dual modulation effects of single herbs on the body, you can see how it becomes even more difficult to predict how the complex interactions of several herbs in one formula will affect the body. The interactions between active ingredients contained in the herbs, dosages of each ingredient and processing methods, all contribute to make a unique product that can have completely different effects from a similar formula if any of these things are altered. Furthermore, these formulas may react differently from person to person or on a body that is healthy, stressed or ill. This is why the empirical knowledge passed down through the TCM practitioners and various TCM classics is invaluable. The practitioner's skill in knowing what herbs can be combined, in what amounts, and how they should be prepared cannot be overlooked. This knowledge, combined with today's new scientific methods, help us to identify new active ingredients and understand how best to prepare and combine herbal ingredients to make even better TCM formulations for health maintenance.

By understanding the concept of dual modulation, you can understand why there is such variety in the efficacies of similar products. It is also essential to understand this concept in order that TCM formulas can be applied appropriately for maximum health benefits.


Tao Yufeng, What is Chinese Medicine? - A Home Companion to Chinese Medicine, Shanghai Education Publishing House 1997:102-105.
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Written By:
Prof. Jiang Shufa (oб)
Senior Engineer, Shanghai Institute of Materia Medica
Angela Collingwood MSN, Integrated Chinese Medicine Holdings Ltd.
Jennifer Eagleton, BA & MA (Asian Studies), Integrated Chinese Medicine Holdings Ltd.
Rose Tse, Integrated Chinese Medicine Holdings Ltd.