THE JADE SCREEN
The Story Behind Yupingfeng San
Jade Screen Powder, Yupingfeng San (yu = jade; pingfeng = screen; san = powder) is a famous formula of Chinese medicine (1). The reference to jade reflects value and strength, and screen indicates protection, as a barrier. The term ping, by itself, means a screen, as does pingfeng. The modifying term feng (= wind) clearly defines this as a barrier to invading wind, the traditional carrier of illness. A barrier of this type is different from a mesh screen, called sha (meaning gauze or wire mesh), as in a screen window (shachuang), which lets the wind pass right through. One should think, instead, of the jade barriers used to prevent entrance of evil influences into a room as part of the Chinese art of fengshui (see illustration).
According to ancient concepts in China, the body's resistance to adverse external influences is maintained by closing the sweat pores in the skin, the entry portals for "evil influences." Control over the pores is regulated by the action of weiqi, or defensive qi, that circulates at the surface of the vessels. According to the traditional view, weiqi is generated as part of the qi derived from food, transmitted by the spleen and controlled by the action of the lungs. If a person easily perspires, this is an indication that the weiqi is weak and that the pores are too freely opened. Thus, pathological "wind" can penetrate into the skin through these open pores and gain a foothold in the muscles; from there it can initiate a disease process which, if not halted, can proceed to the inner organs and cause great debility, even death. Jade Screen Powder was designed to boost the weiqi and arrest sweating by closing the pores; it may be incorporated in modern formula guides either in the astringent section or qi tonic section.
The formula was discussed by Zhu Danxi and recorded in the book Danxi Xinfa (Zhu Danxi's Central Methods, literally, "heart" methods), which was most likely written by his students. Later, this book was combined with another such work called Yi Yao (Essentials of Medicine) to yield Danxi Zhifa Xinyao, which has been translated to English (2). The original name of the formula was probably Si Chao Baizhu San (Four Ingredients Fried Atractylodes Powder), which had calcined oyster shell added to the three ingredients currently specified for Jade Screen Powder: astragalus, atractylodes, and siler. In this formula, siler and astragalus regulate the weiqi; atractylodes is used to invigorate the spleen function: with astragalus, it boosts the generation of qi and astringes sweating. Oyster shell was included to further astringe sweating.
The formula is barely referenced in the literature of the next several centuries, until the modern era. Qing Bowei, a leading physician of the 20th Century, commented on the use of the formula and its special design (3):
In general, a weakened constitution is more susceptible to external contractions and, as a result, there are chills and fever and spontaneous perspiration that is most often a consequence of an insecurity of the weiqi. Jade Screen Formula is used to secure the exterior and eliminate the pathogenů.Jade Screen Powder treats the contraction of pathogens in deficiency patients in those cases where the pathogen itself has not been resolved. The intention of the prescription is to augment the qi and dispel the pathogen. In general, astragalus and siler are believed to be mutually potentiating. Astragalus joins siler and there is no need for concern about securing the pathogen. Siler meets astragalus and there is no need for concern about dispersing the exterior. In reality, there is dispersion in the midst of supplementation and supplementation in the midst of dispersion. This differs from 'support the correct and secure the exterior." For this reason, if there are no superficial pathogens at all, administration of siler will actually provide an opportunity for pathogens to attack the body.
The latter part of this discussion points to the fact that siler is usually used to resolve surface congestion, opening the pores and letting out sweat (and, at the same time, letting out the pathogen). But here, it is used in a formula designed to restrict sweating. The interaction between astragalus and siler is the key. If astragalus is used alone, then it is feared that it will close up the pores and lock in (secure) the pathogen, so that it can't get out; siler prevents this problem by providing its dispersing effect. If siler is used alone, it disperses the exterior when there is already sweating and this will drain the vitality of the patient, and thus leave the person at risk for damage by the pathogen. For instance, in a weak patient, even if not ill, if siler were taken indiscriminately (without proper formulation to prevent excessive surface release) it would invite pathogens in through the opened pores of the exterior. Astragalus prevents this problem by assuring adequate control of the surface. So, there is dispersing and supplementing simultaneously; this approach differs from that attained by combining the method of supplementation ("support the correct") and the method of astringing ("secure the exterior"), a potent protective measure which is considered inappropriate when a pathogen is already present. Traditionally, it was said that siler and astragalus contradicted each other; therefore, the inclusion of these together as key elements of a formula required some explanation.
A somewhat similar interaction between cinnamon twig and peony, in regulating the surface and controlling sweating-with cinnamon being dispersing and inducing sweating and peony being restraining and restricting sweating-is a well-accepted pattern for treating disorders with weak weiqi. A comparison has been made between use of Jade Screen Formula and Cinnamon Combination (Guizhi Tang) in the Advanced Textbook of Traditional Chinese Medicine and Pharmacology (4):
Jade Screen Formula and Cinnamon Combination are both indicated for exterior-weakness syndrome marked by spontaneous sweating and aversion to wind. But Jade Screen Formula is also good for benefiting qi and strengthening the surface to stop sweating, and is indicated for the syndrome marked by spontaneous sweating. Cinnamon Combination is good for dispersing cold from the surface and regulating ying and wei, and is indicated for exterior syndrome due to affection by wind-cold.
Basically, Jade Screen Formula has a greater astringent quality (and is placed with the astringent formulas in the textbook): sweating is a primary indicator for its use. By contrast, Cinnamon Combination has a stronger warming and dispersing quality (and is placed with the formulas for relieving exterior syndrome marked by cold): wind-cold affliction is the primary indicator. Astragalus, which is the lead ingredient of Jade Screen Formula is a tonic that astringes sweating; cinnamon twig, the lead ingredient of Cinnamon Combination, is warm and spicy, dispersing the surface congestion.
A standard description for use of the formula was developed (5):
Jade Screen Formula benefits qi, consolidates the surface, and arrests diaphoresis. It is indicated in the treatment of surface deficiency with a weakness of weiqi, fear of draft [dislike exposure to wind and concerned about easily becoming ill], resting diaphoresis [spontaneous perspiration], pallor, pale tongue, white tongue fur, floating, weak, and soft pulse and a history of frequent contraction of draft evil [wind disorders, particularly wind-cold].
In recent clinical work in China, Jade Screen Formula became a preferred method for treating children who, because of their deficiency status, were experiencing frequent infections such as common cold and influenza. In one study of its ability to prevent recurrent respiratory infections in children (6), a slightly modified Jade Screen Formula was given was administered in two daily doses, given every other day, over a period of about 15 weeks for one group of children and 6 months for a second group. The children, classified as being "weak," had a high frequency of infections, with 1-2 episodes per month as the criteria for inclusion in the study group. With treatment, these children had fewer incidents of respiratory infections; in monitoring the incidence of infections month by month among those treated for six months, it was shown that the frequency of infections dropped markedly over the first five months, then stabilized, suggesting that there was a cumulative effect of regularly administering the formula
The formula administered in that study was elegantly designed. Beginning with the original Si Chao Baizhu San (including oyster shell), the physicians included citrus (chenpi) to regulate central qi and avoid a potential problem of qi stagnation from administering a tonic formula over a prolonged period, and included dioscorea (shanyao) to nourish the spleen yin, thus avoiding parching of the yin by the regular use of atractylodes and citrus. The ingredients, 9 grams of each (except 6 grams of citrus) were ground to powder and administered in doses of 3 grams each time (so 6 grams in one day). The usual dose of Jade Screen Powder in adults is 6-9 grams each time, twice daily.
While children usually suffer from damp syndromes rather than dryness, adults may easily suffer from damage to the yin, weakness of blood, or drying of membrane fluids due to various causes. A problem with using Jade Screen Formula for long-term preventive medicine in adults is that the original formulation is best suited to those who have a tendency towards spleen weakness with damp accumulation, for which atractylodes plays an important role (atractylodes also has some immune enhancing effects). For persons who suffer dryness, the formula can be modified by expanding it to include the principle elements of Shengmai San, which is used as a tonic for qi and yin deficiency and is also an astringent formula. One can add its three ingredients, codonopsis (in place of ginseng), schizandra, and ophiopogon to Jade Screen Powder. By developing the formulation this way, the dispersing action of siler is given less attention (as appropriate for the preventive purposes), with more reliance on the approach of "support the correct and secure the exterior" that is suited to disease prevention. Once a pathogen has entered and begun the disease process, it is better to use formulations that are aimed at fighting the disease, as is done with Yin Qiao San and other anti-infection preparations. Jade Screen plus Shengmai San can be used again for faster recovery.
During the latter part of the 20th Century, the immune enhancing function of astragalus was revealed in numerous laboratory experiments (7). These experiments were performed in order to demonstrate by scientific methods that traditional medical indications could be explained in modern terms. In this case, studies were devised to show that protection against evil influences by enhancing weiqi corresponds to immune attack against viruses and bacteria by enhancing immunoglobulin production (e.g., IgA). Since astragalus is not normally used alone, TCM specialists often recommended use of Jade Screen Powder as a basic immune tonic. Alternatively, Buzhong Yiqi Tang (Ginseng and Astragalus Combination) would be recommended; that formula has less astragalus but is well-known for its use in treating weakened patients. To enhance the immune boosting action of Jade Screen Powder, codonopsis would be added (8).
In a review of the formula's pharmacological effects in relation to the immune system (9), it was evident that the prescription could not only affect immunoglobulins, but also mononuclear macrophages, T-lymphocytes, natural killer cells, and other aspects of the immune system damaged by experimental interventions. Astragalus had limited effect on immune functions that were normal. Reviews of clinical applications of Jade Screen Powder published in 1989 (10) and 1992 (11) indicated the following uses:
Some of these applications involve surface disorders and reflect the traditional use of the prescription; in other cases, the formula has been applied for conditions where astragalus is believed to be of benefit, such as for cardiac disorders.
Based on the traditional view, Jade Screen Formula is most appropriately prescribed during the resolution phase of an acute ailment. This is when there is evidence of having passed the worst (e.g., fever abates, some symptoms improve), with the pathogen and its influences not yet completely gone. At this point, tonification is used to restore strength to the patient, while the dispersing action of siler is relied on to help complete the process of eliminating the pathogen via the surface. However, because of the focus on immune-enhancing effects, the formula has come to be recommended to prevent illness, such as during the winter cold/flu season. It has also been suggested as a preventive remedy for seasonal allergies as well as a treatment for allergic reactions (both sinus congestion and skin rashes).
For treatment of allergies, a modified version of Jade Screen Formula is often used. A well-studied formulation for this purpose is described by Lin Wensen of the Nankai Hospital in Tianjin (12, 13). Bupleurum, schizandra, and mume are added to the base Jade Screen prescription. Bupleurum, like siler, has a surface-relieving action; schizandra and mume have astringent functions; additional tonics are also sometimes added, such as codonopsis and tang-kuei. According to the pharmacology and clinical studies of Jade Screen Formula (8-10) and this modification, IgE, which mediates allergy, is decreased, but IgA, which improves resistance to infection, is increased. With the specific symptom of nasal stuffiness due to allergy, xanthium and magnolia flower are recommended as further additions (4, 13).
A modern concept of immunological balance is that a strong immune response will destroy invading viruses before a virus-based illness can develop, yet the immune system will not respond adversely to normal substances, such as pollens. This potential for a dual impact was demonstrated recently (14) when it was shown that asthmatics could be treated by immune tonics (such as astragalus, codonopsis, and licorice) for several weeks and would then have reduced airway constriction when challenged by an allergen. From the TCM perspective, the body surface is regulated by the herbs so that wind, such as winter wind-cold or wind-damp, or spring wind-heat, cannot invade and cause symptoms. Based on the modern interpretation, Jade Screen Formula and its modifications need not be used solely for treating surface ailments, but may be used also for antiviral therapy because of its immune enhancing activity. For example, the combination of Jade Screen Formula and Shengmai San has been investigated as a therapy for coxsackie B viral infection of the heart (15), which is responsible for most cases of viral myocarditis.
Jade Screen Formula was developed originally as a treatment for spontaneous sweating that was due to deficiency syndrome or was the result of a pathological influence still lodged in the surface. More recently, it has become a therapy for prevention of cold, flu, and allergic rhinitis, and a treatment for viral infections, nephritis, and other disorders. These newer uses are derived both from an analysis of the formula by traditional principles and from successful applications of this tonic formula to patients who show signs of deficiency syndrome. Research indicates that the formula regulates immune functions, aiding in the fight against infections but reducing allergic responses. Modifications of the formula are made to address particular applications, but most adjustments emphasize one or both of the basic therapeutic actions, which are tonification and surface regulation. Thus, additions might include other qi tonics (codonopsis, dioscorea), or other types of tonics (e.g., tang-kuei to nourish blood, ophiopogon to nourish yin), herbs that disperse congestion at the surface (e.g., bupleurum, cinnamon twig, pueraria) and herbs that astringe sweating (e.g., oyster shell, schizandra, mume, light wheat).