Background
Traditional Chinese Medicine Constitution (TCMC, named
Tizhi in Chinese) refers to an integrated, metastable and natural specialty of individuals in morphosis, physiological functions and psychological conditions, formed on the basis of innate and acquired endowments in the process of life[
1,
2]. The TCMC not only determines the susceptibility to certain pathogens and diseases, but also closely related to the development and the prognosis of diseases[
3,
4].
Generally, TCMC is divided into balanced constitution also known as Normality (
Pinghe in Chinese) constitution and Unbalanced/Biased (
Pianpo in Chinese) constitution which can be further classified into several subtypes such as Yang-deficiency, Yin-deficiency, Phlegm-wetness, Qi-deficiency, Wetness-heat, Blood-stasis, Qi-depressed etc.[
5‐
7]. According to TCM philosophy, Normality constitution represents an overall healthy state and people with unbalanced constitutions are prone to certain diseases (at least theoretically).
The type of TCMC formation is mainly determined by congenital endowments; nevertheless acquired factors including individual factors (lifestyle, dietary habits, emotion status, history of diseases and treatments) and environmental factors maybe also play a role in the process of TCMC development[
1,
8‐
11]. To date few clinical investigations on the influencing factors of TCMCs were conducted and when conducted they have primarily focused on one type of unbalanced TCMC or considered limited associated factors. There is a dearth of studies involving large study population and applying rigorous research design to detect the efficacy of various acquired factors on the formation of TCMCs.
From the perspective of TCM therapeutic theory, it is of great significance to preserve ones healthy based on his/her TCMC status. Finding the potential factors related to the biased TCMCs and then trying to eliminate the effects to maintain or obtain a new balanced TCMC is the ultimate goal in keeping health or prevention of diseases. For example, for a person diagnosed with Yang-deficiency constitution a long-term prescription with the function of tonifying Yang-qi is required. However, such prescriptions for a biased constitution might be invalid theoretically due to the interference of various confounding factors related to his/her constitution. Thus it is imperative to identify and understand confounding factors and decrease their influence to a minimum in preserving health.
The aim of this study was to survey TCMC types distribution of local Chinese women between 30 and 65years old in Hong Kong; and to identify factors associated with biased constitutions. The significance of this study is to provide scientific information for local middle-aged and elderly women to prevent the imbalance of their constitutions. In addition, more importantly, to provide comprehensive and new way of thinking to improve health.
Discussion
As TCMC could indicate the overall health status of individuals without any serious diseases, and therefore has enormous potential application in treating Not-Yet-Ill (
Zhi Wei Bing in Chinese, means preventive treatment of diseases) and health care, it is becoming a research and clinical interest. Although a large number of epidemiological investigations on constitution have been performed during past one decade[
15,
23‐
29], data on related influencing factors of unbalanced TCMCs are sparse. The present study was one of a limited number of investigations exploring TCMC types among Chinese women in Southern China and associated factors. To our knowledge, this is the first investigation to examine the association between TCMC type and extensive potential influencing factors, rather than only observing the distribution of TCMC types among certain group of people with different demographic characteristics. The findings of this study would help TCM professionals and researchers to strengthen their understanding of the acquired influencing factors of TCMC and thus provide reference for their future studies.
The findings of the present investigation showed that more than eighty percent of adult Chinese women in Hong Kong have unbalanced TCMC, among them more than sixty percent have combined unbalanced constitutions with two or more types. Based on TCMC theory, this finding indicated that they were not in the normal state of health. The most common unbalanced TCMC types among the study subjects were Qi-deficiency, Phlegm-wetness and Yang-deficiency, in both groups with good health and poor health. This finding is basically consistent with that of a previous investigation[
27] involved 6525 participants conducted in Guangzhou where climate and environment are similar with Hong Kong. However, the finding of our study differed from previous investigation in Hong Kong which reported nearly half of the respondents in Hong Kong had Normality constitution, and dominant frequency of the unbalanced TCMC types were 9.88% of Yang-deficiency, 9.59% of Qi-deficiency and 8.22% of Wetness-heat constitution respectively, much lower than the distribution percentage in our study[
28]. The difference may probably be caused by sampling-related issues. Our study involved the local Chinese women aged from 30 to 65 years old whereas the other study included extended age-range (local women over 15 years old).
The distribution of the dominant unbalanced TCMC types may be closely related to the common life-style of Hong Kong dwellers and Southern-China living environment. Specifically, the formation of Qi-deficiency, based on the theory of "over work damages Qi", might be closely related to prolonged intensive work which is very universal in Hong Kong due to intense competition, fast-paced lifestyle and high pressure from work. Qi-deficiency constitution, characterized by fatigue, low voice, dizziness and prone to cold, is therefore gradually formed[
30]. The widespread of Phlegm-wetness constitution among Hong Kong Chinese women might be ascribed to local geographic environment and climate to a large extent. Hong Kong is located at the outlet of the Pear River, by the north of South China Sea and to the south of Nan Ling Mountain, which result in formation of the unique environment and climate. The damp and rainy weather might contribute to the formation of Phlegm-wetness constitution according to TCM philosophy[
28]. With regard to the popularity of Yang-deficiency constitution in study subjects, it might be attribute to dietary habit and living habit, which mainly refer to drinking cold drinks and overuse air conditioning whether it is in summer or not. Exposure to these "cold pathogen" for a long period of time may damage individual Yang-qi and thus lead to the formation of Yang-deficiency constitution from the theory of Chinese medicine[
28].
The results of the present study showed that the most important associated factor with unbalanced TCMCs is health status. It is well-known that TCM constitution tends to reflect steady state of individual’s health, unbalanced TCMC often represents deteriorated health status even some status diagnosed as "no disease" by western medicine. On the other hand, prolonged chronic illness may conversely affect individual’s TCMC, leading to unbalanced TCMC. In this study, suffering from mild to moderate diseases was associated with some types of unbalanced TCMCs such as Qi-deficiency, Phlegm-wetness, Yang-deficiency, Yin-deficiency, Blood-stasis and Qi-depressed constitutions. This finding confirms the validity of the Chinese Medicine theory of constitution.
In contrast, our study found that physical exercise as the most important protective factor for several certain unbalanced TCMCs such as Qi-deficiency, Phlegm-wetness, Wetness-heat, blood-stasis and Qi-depressed constitutions. The explanation could be as follows: Doing exercise moves Qi in the body and dissolve blood stasis thus improve Blood-stasis and Qi-depressed constitutions. Smooth and fast flow of Qi would help to dispel wetness and thus to prevent the formation of Phlegm-wetness and Wetness-heat constitutions. TCM also holds that "movement could benefit Qi", so regular exercise is effective in improving Qi-deficiency constitution. In addition, the findings indicate that although physical exercise demonstrated protective effect on Wetness-heat constitution formation, only long-term physical exercise could improve wetness-heat condition significantly, the longer exercise duration, the better effect achieved. The reason is that wetness-heat, based on TCM philosophy, is a viscous and lingering pathogen which is very hard to eliminate and therefore usually need long-term treatment and nursing to resolve. However, it does not show any effect on improving Yang-deficiency and Yin-deficiency constitutions which are usually managed via medications or dietary treatment.
"Most overweight people are phlegmatic", as the classical theories of Traditional Chinese Medicine, is proved once again by our study whose result shows overweight is positively associated with phlegm-wetness constitution significantly, and also being consistent with the results of two previous studies[
31,
32]. Interestingly, although overweight is regarded as an independent risk factor for Phlegm-wetness constitution, it might be a protective factor for Yang-deficiency constitution according to our study result, the high BMI, the less susceptibility for Yang-deficiency constitution. The similar conclusion had been achieved by Prof. Zhu whose study showed that slim body build was significantly positively correlated to Yang-deficiency constitution[
33]. One plausible explanation could be that feeling cold is the most distinguished feature to determine Yang-deficiency constitution, while too much subcutaneous fat with the function of keeping body temperature might help fat people improve cold sensation. The findings indicate that high educational level is another precipitating factor for Phlegm-wetness constitution formation, participants received higher education are more likely to emerge Phlegm-wetness constitution than those with low educational level. The possible explanation might be that the women with high educational level are often engaged in senior white-collar jobs with higher income and therefore usually experience sedentary life and intake high quality of diet. According to TCM philosophy, if too many nutrients absorbed into the body exceed the spleen function of transportation and transformation, it would not be transformed into Qi, blood and body fluid, but could be transformed into phlegm and dampness.
Mental work and unpleasant emotional life are also proved to be associated with unbalanced TCMCs. The present study confirms that mental work is an independent risk factor for Yin-deficiency constitution formation. The result demonstrates that those engaged in mental work are prone to get Yin-deficiency constitution than those engaged in manual work, which is entirely consistent with the recognition of the book of The Yellow Emperor’s Inner Classic which as the earliest classic of TCM believes that over thinking and excessive anxiety may consume Yin and blood secretly and gradually. Based on TCM theory, besides congenital endowment, moodiness is one of most important causes bringing about Qi-depressed condition. Our findings confirm that women have been experiencing less-than-satisfactory emotional life or had experienced less-than-satisfactory emotional life are more prone to Qi-depressed constitution than those with happy emotional life, indicating that negative emotion is indeed a precipitating factor for Qi-depressed constitution.
An important discovery of the present study is that reproductive history is also an independent protective factor for Yang-deficiency constitution, which has never been reported before. Moreover, with the number of full-term pregnancies increasing, the protective effect is more obvious, indicating reproductive history might be favorable for preventing Yang-deficiency formation. But it is unclear whether which is caused by pregnancy, reproduction or other unique postpartum managements. In our opinion, we tend to think that pregnancy and reproduction, as the process consuming Qi and blood, would reflectively switch on body’s self-adjustment function and then stimulate the generation of Yang-qi, leading to the improvement of Yang-deficiency.
To date, whether aging is a precipitating factor or a protective factor for unbalanced TCMC formation is still not sure. Deng claimed that unbalanced TCMCs are more prevalent among old people than the younger[
34], however, his investigation only involved 224 participants and without providing any background information of the participants and the details of research methods, so his conclusion is doubtful. The findings of other investigations with large samples were also not totally consistent[
15,
26‐
28]. For instance, Chen’s investigation involving 2168 subjects[
26] showed that the prevalence of Qi-deficiency, Yang-deficiency, Phlegm-wetness and Blood-stasis among older people is higher than young’s, however, Huang’s results reject accepting Yang-deficiency are more common among elderly than young people[
28], the results of Wu’s study involving 2043 subjects[
27] and Wang’s study containing 8448 participants[
15] demonstrated that there was no significantly difference between old people and young people in the prevalence of Phlegm-wetness. But it needs to be pointed out that all of them only investigated the distribution of unbalanced TCMC types in different age groups, without using logistic regression method to systematically examine the efficacy of age on the formation of TCMC types, so their findings were still not completely convincing. Two studies aiming to explore the associated factors with Phlegm-wetness constitution[
31] and Yang-deficiency constitution[
33] using logistic regression method also indicated that age was not significantly related to those two types of unbalanced TCMCs. The findings of the present study support aging as a protective factor for the formation of Qi-deficiency, Yin-deficiency, Blood-stasis, Qi-depressed and Wetness-heat constitutions. The potential explanation is that old women usually stay at home and enjoy a leisure life without carrying out heavy work and facing with various pressures, reducing the consumption of Qi and Yin and thus improving Qi and Yin deficiency. With a wealth of experience, elderly are usually good at managing their mood than younger, this would effectively avoid liver-qi stagnation and thus prevent the formation of Qi-depressed and Blood-stasis constitutions. The decline of Wetness-heat constitution incidence among old people may be related to the decrease of their Yang-qi as their age increases, thus contributing to suppress the generation of internal-heat. In summary, so far there is no consensus on the effects of age on unbalanced TCMCs formation, therefore declaring that age is an influencing factor to unbalanced TCMC types might be not justified.
It is universally recognized that smoking is harmful to health, so based on this fact, smoking theoretically should play a role in the formation of unbalanced TCMCs. Wang’s study demonstrated that smoking could promote the formation of Phlegm-wetness constitution[
33]. But the present study did not find that smoking would precipitate any types of unbalanced TCMCs formation. A reasonable explanation for this phenomenon is that the sample size with smoking habit is too small and most of them only consume very few cigarettes per day, which might be still not enough to cause the imbalance of their TCMC.
Based on TCM philosophy, the amount of unbalanced TCMC types owned by one person at the same time, representing the complexity of TCMC, usually reflects the severity of his/her constitutional imbalance. Since age, poor health status and exercise habit showed the obvious effect on the formation of most unbalanced TCMC types, and therefore significantly affected the complexity of individuals’ TCMCs. Unpleasant emotional life did not play a significant role in the formation of unbalanced types except for Qi-depressed constitution, but pleasant emotional life did decrease TCMC complexity of the studied participants, further proved the rationality and the science of the theory originated in The Yellow Emperor’s Inner Classic that emotion is one of the important pathogenic factors.
This study has several limitations. First, the study sample was not recruited via rigorous random sampling method, which may have brought the risk of not being representative enough to generalize the results of all Hong Kong Chinese women. Secondly, although there was no significant difference between the study participants and female long-term residents in age distribution, their age distribution did not match very well, which may be likely affect the objectivity of the results, especially to affect the judgment about the effect of age on the formation of unbalanced TCMCs. Thirdly, other potential influencing factors including dietary habit and work-rest manner which could also affect TCMC formation according to TCM theory, not considered in the study. This may also confound the results.
Conclusion
Based on the results of this study, some mainly conclusion could be drawn:
First, biased constitutions are common among middle-aged and elderly Chinese women in Hong Kong, indicating it is feasible and necessary to preserve their health and to promote the rehabilitation of their diseases through managing their unbalanced TCM constitutions.
Secondly, poor systemic physical condition is the most important dominating-related factor for the formation of almost all unbalanced TCMC types except for Inherited Special Constitution which is mainly determined by congenital endowments according to TCMC theory. In contrast, regular physical exercise is the most protective factor for most unbalanced TCMC types. This demonstrates that physical condition and exercise history must be treated as the primary influencing factors in such studies about TCMCs.
Thirdly, some special factors may cause certain unbalanced constitutions. For instance, overweight and high educational level contributes to the formation of Phlegm-wetness constitution, mental work contributes to Yin-deficiency constitution and unpleasant emotional life leads to Qi-depressed constitution. This could be explained by TCMC theory, which demonstrates its value.
Last but not least, age as one of the risk factors for unbalanced constitutions in the current TCMC theory might not be justified, indicating some recognition of the current TCMC theory is not entirely correct. Therefore, it is still significant and necessary to confirm the effects of potential factors on unbalanced constitutions formation in further studies with big sample and rigorous design.
Acknowledgments
We are indebted to all women who kindly participated in this investigation, and thank Dr. Wendy Wong (Family Medicine Unit, Department of Medicine, Li Ka Shing Faculty of Medicine, HKU) for her modification on several items of original version of TCM Physical Constitution Scale. We also gratefully acknowledge the help of Mr. Sherman Ou (T&M Education Service limited), Mrs. Wong Sai Lin (F.T.U. Tung Chung District Service Office), Mr. Chan Wing Kin and Ms. Cindy Chiu (F.T.U. Yuen Long District Service Office), Mrs. Cheung Choi Sheung (D.A.B. Sham Shui Po District Branch), Mr. Jack Cheung (D.A.B. Kwun Tong District Council), Mr. Kong Chack Ho (Eastern District Councilor), Mrs. Siu Lai Nar (Residents Will in Chai Wan), Mrs. Chiu Wah Kuen (The Women’s Association of Central and Western District), Mrs. Chan Mei Lin (Yuen Long District Councilor), Y. C. Fu (Eastern District Councilor), Mr. Siu Hin Hong and Ms. Lim Sau Lai (Sha Tin District Councilor), Ms. Lai Suet Ying (F.T.U. Kwai Tsing District Service Office), Mrs. Chung Mau Yu and May Yeung (China Merchants Finance Holdings co., LTD), Mrs. Yeung Sau Ying (The boy’s and Girl’s Clubs Association of Hong Kong), Mr. Doug Wong (Information Technology Service Center, The Hong Kong University of Science and Technology), Mr. Tsui Kam Chuen (The Hong Kong Society of Chinese Medicines Limited), Mr. Carson Ng and Mr. Michael Tien (Tsuen Wan District Council), Mrs. Kennise Ng (Oriental Int’l Health Products Co., Ltd) and Mrs. Choi Yuet Sim (The Women’s Association of Ap Lei Chau) for their invaluable assistance in subjects recruitment, workshop organization and data collection. We also appreciate Prof. Colman McGrath from Faculty of Dentistry, the University of Hong Kong, for his English language proof-reading to improve the content of the manuscript. This work was supported by National Natural Science Foundation of China (No. 81360513).
Authors’ contributions
Youzhi Sun conceived of the design, carried out the study and drafted the manuscript; Jianping Chen was in charge of the study work, advice in the study design; Pei Liu participated in coordination and helped to perform the statistical analysis and manuscript writing; Yi Zhao and Steve An Xue gave expert advice in the study design and participated in manuscript writing; Lei Jia, Yanhua He, Xiao Zheng, Zhiyu Wang and Neng Wang participated in the acquisition of data. All authors read and approved the final manuscript.