A Systematic Review on Sasang Constitutional Type-Associated Susceptibility to Disorders in Korea

Abstract

Background/Objective:

Sasang constitutional medicine is a component of traditional Korean medicine that classifies individuals into four Sasang constitutional types (SCTs) by their physical and psychological traits. Each SCT is known to show different susceptibilities to disorders. This systematic review investigated the effect of SCT as a risk factor for various disorders.

Methods:

A systematic literature survey was conducted by searching seven databases for all articles on the prevalence rates of disorders according to SCT and sex.

Results:

From 14,272 relevant articles, 15 studies (13 disorders) were ultimately identified to verify different prevalence rates by SCT. Of the 13 disorders, 6 (prehypertension, general obesity, abdominal obesity, metabolic syndrome, diabetes mellitus, and irritable bowel syndrome [IBS]) had a significantly different prevalence by SCT. Metabolic syndrome and its associated disorders showed the highest prevalence in Taeumin-type individuals, whereas IBS was most prevalent in Soeumin-type individuals. In general, these findings were consistent with the results obtained in an analysis of male and female participants.

Conclusions:

This study revealed that susceptibility to disorders was affected by SCT to some extent. Further studies are needed to determine the concrete features of SCT-related susceptibility, which may be helpful in preventive medicine with Sasang constitutional practice.

Introduction

Genetic variations, such as single nucleotide polymorphisms, are strongly associated with susceptibility to various diseases, including hypertension, diabetes, and cancer.¹ For example, people with mutated BRCA1 and BRCA2 genes have an elevated risk for breast cancer.² An individual's genetic profile can contribute to various phenotypic characteristics, including susceptibility to disorders or environmental factors and drug responses.^3,4 In this regard, the authors noted the effect of Sasang constitutional medicine (SCM) on individual heredity for the prevention and treatment of disorders.

SCM, a branch of traditional Korean medicine, categorizes individuals into four constitutional types: Taeumin (TE), Soeumin (SE), Soyangin (SY), and Tayangin (TY). Sasang constitutional types (SCTs) are determined according to an individual's innate temperament and body shape, and they exert a profound effect on each person's risk for contracting disease and response to drugs.⁵ This Korean-originated concept of SCT classification is now being interpreted with modern genetic science. For example, variants of fat mass and obesity-associated genes are assumed to influence constitutional discrepancy for body mass accumulation, resulting in different physiques among SCTs.⁶

Since the introduction of SCM by Jema Lee (AD 1837–1900), a series of studies have investigated vulnerability to disorders according to SCT. In these studies, TE, SE, and SY showed significant differences in the prevalence rates of various chronic diseases (e.g., diabetes, hypertension, obesity).^7,8 Regarding incidence, SCT also displayed different patterns. For example, 24.3% of TE individuals were newly diagnosed with type 2 diabetes mellitus during a 10-year survey, followed by SY (14.3%) and SE (12.1%) individuals.⁹

Taken together, these findings raise the possibility that SCT may be a potent factor in determining disease susceptibility in each person. One study showed the pattern of prevalence for 27 types of disorders according to SCTs using 1453 participants;¹⁰ however, this study did not compare data between men and women. Therefore, there is a need to characterize the prevalence rates of diseases according to SCT and sex.

To investigate the contribution of SCT to susceptibility to disorders, the authors surveyed articles reporting the prevalence of disorders according to SCT, which is expected to be a foundation of further scientific investigation into SCM.

Materials and Methods

Data sources and keywords

A systematic literature survey was conducted using publicly available electronic databases. Searches were performed for all studies published before August 2015 in PubMed (http://www.ncbi.nlm.nih.gov/pubmed) and Google Scholar (http://scholar.google.com), along with four Korean electronic databases: Regional Information Sharing System (https://www.riss.net), Korea Institute of Science and Technology Information (http://society.kisti.re.kr), Korea Institute of Oriental Medicine OASIS (http://oasis.kiom.re.kr), and a library database (http://archive.is/libweb.dju.ac.kr). Searches were conducted by using combinations of the following keywords: “Sasang,” “constitution,” “prevalence,” “incidence,” “Sasang type,” and “constitutional distribution.” A secondary search of all references listed in any included study was then performed to identify titles matching the inclusion criteria. Korean terms adapted from those listed above were used for the Korean databases.

Eligibility criteria

Articles were screened by using the following inclusion criteria: (1) reported prevalence rates of disorders according to SCT in Korea, (2) included more than 400 participants from the general population, (3) showed information regarding prevalence rates for both male and female patients except for sex-dependent disorders (e.g., alopecia, irregular menstruation, ovarian neoplasm, and uterine fibroid), and (4) provided clear diagnostic criteria for disorders. Articles filtered by these criteria were read in full by the authors, who together then determined the suitability of each article. Articles that did not meet all of the necessary inclusion criteria were excluded from this study (Fig. 1).

FIG. 1.

Flowchart of the studies included in this analysis.

Review process

The articles that passed the filtering criteria were collected, and data, including population, sex, age, disorder, and SCT (TE, SE, or SY type), were extracted. The TY type was excluded from this study because of the low frequency of TY-type individuals in the general Korean population (0.03%–0.1%).⁵ If any article simultaneously concerned multiple diseases, then it was divided into separate studies of each disease.

Classification of Sasang constitution and diagnostic criteria of each disorder

The diagnostic tools for SCT classification in the collected studies are as follows: Sasang constitutional analytical tool (SCAT), Questionnaire for the Sasang Constitution Classification II (QSCC II), the revised QSCC II (QSCC II+), or SCM specialists. SCAT is a web-based SCT diagnostic tool developed by the Korea Institute of Oriental Medicine that combines four individual quantitative data: facial structure, body shape, voice analysis, and questionnaire responses.¹¹ QSCC II is a self-SCT diagnostic questionnaire consisting of 121 inquiries and QSCC II+ is simplified into 54 questions.¹² SCM specialists refer to traditional Korean medicine doctors specializing in SCM. The diagnostic criteria for each disorder are summarized in Table 1.

Table 1.

Diagnostic Criterion for Each Disorder

Disorder	Definition
Prehypertension¹³	SBP ≥120 mm Hg and <140 mm Hg or DBP ≥80 mm Hg and <90 mm Hg²⁵
General obesity¹⁴	Body–mass index ≥25 kg per meters squared²⁶
Abdominal obesity^14,15	WC ≥90 cm in males and ≥85 cm in females²⁶
Metabolic syndrome^16,17	≥3 of the following criteria satisfied:²⁷ (1) FBG ≥100 mg/dL,²⁸ (2) SBP ≥130 mm Hg and/or DBP ≥85 mm Hg, (3) triglycerides ≥150 mg/dL, (4) HDL-C ≤ 40 mg/dL in males and ≤50 mg/dL in females, or (5) WC ≥90 cm in males and ≥85 cm in females²⁶
Diabetes mellitus¹⁸	FBG ≥126 mg/dL²⁹
Functional dyspepsia¹⁹	≥1 of the following symptoms:³⁰ (1) postprandial fullness, (2) early satiation, (3) epigastric burning, or (4) epigastric pain lasting ≥3 mo since onset before 3 mo or more
IBS²⁰	Recurrent abdominal pain or discomfort on ≥3 d per month in the last 3 mo associated with ≥2 of the following symptoms:³¹ (1) pain relieved with defecation, (2) onset associated with a change in frequency of stool, or (3) onset associated with a change in the form of stool; symptom onset ≥6 mo before diagnosis
COPD²¹	FEV₁/FVC <0.7³²
Osteoporosis²²	BMD value ≥2.5 below the young adult female reference mean³³
Alopecia²³	Clinical manifestation of male hair loss, the pattern of which is divided according to Ogata's classification system³⁴
Irregular menstruation²⁴	Variation in menstrual cycle length
Ovarian neoplasm¹⁰	Diagnosis of benign or malignant tumor in ovaries by medical doctors, with positive clinical test results
Uterine fibroid¹⁰	Diagnosis of benign uterine fibroid by medical doctors, with positive clinical test results

SBP, systolic blood pressure; DBP, diastolic blood pressure; WC, waist circumference; FBG, fasting blood glucose; HDL-C, high-density lipoprotein cholesterol; IBS, irritable bowel syndrome; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory value in 1 second; FVC, forced vital capacity; BMD, bone mineral density.

Extraction of patient characteristic

The extracted information about population, sex, age, disorder, and the SCT of the patients from each study is shown in Tables 2 and 3 to characterize the pattern of disease susceptibility according to SCT and sex. The population is presented as the number of total participants and is broken down into male and female. The distribution of SCTs is given as a percentage. Age is provided as the mean (± standard deviation) or median.

Table 2.

Participants in Each Article according to Sex and Sasang Constitutional Type

				Portion of participants by TE:SE:SY (%)
Study (year)	Disorder	SCT diagnosis	Participants (male/female) (n)	Total	Male	Female
Jang et al. (2015)¹³	Prehypertension	SCM specialist	2806 (914/1892)	38:28:34	42:25:33	36:29:35
Baek et al. (2014)¹⁴	General obesity, abdominal obesity	SCM specialist	3348 (1191/2157)	40:26:34	44:22:34	38:28:34
Jang et al. (2013)¹⁵	Abdominal obesity	SCM specialist	2528 (909/1619)	41:25:34	45:21:34	39:27:34
Song et al. (2012)¹⁶	Metabolic syndrome	SCM specialist	1617 (593/1024)	41:25:34	45:24:31	39:26:35
Yu et al. (2009)¹⁷	Metabolic syndrome	SCAT	666 (280/386)	55:30:15	52:31:16	56:30:14
Lee et al. (2009)¹⁸	Diabetes mellitus	QSCCII+	1443 (712/731)	47:24:29	48:14:38	46:34:20
Kim et al. (2015)¹⁹	Functional dyspepsia	SCAT	517 (190/327)	30:38:32	17:55:28	37:29:34
Lee et al. (2014)²⁰+	IBS	SCAT	1362 (705/657)	55:13:32	64:13:23	45:14:41
Jung et al. (2010)²¹	COPD	SCAT	1544 (608/936)	57:25:18	66:19:15	51:29:20
Song et al. (2013)²²	Osteoporosis	SCAT	1752 (434/1318)	59:23:17	63:28:9	58:22:20
Lee (2013)²³	Alopecia	QSCCII	409 (409/0)	31:46:23	31:46:23	–
Park and Kim (2007)²⁴	Irregular menstruation	QSCCII	581 (0/581)	30:35:35	–	30:35:35
Lee et al. (2005)¹⁰	Ovarian neoplasm, uterine fibroid	QSCCII+	734 (0/734)	46:34:20	–	46:34:20
Total/mean	13 kinds of disorders	4 diagnostic tools	19,307 (6945/12,362)	TE: 44 ± 10	TE: 47 ± 15	TE: 43 ± 9
				SE: 29 ± 8	SE: 27 ± 13	SE: 28 ± 6
				SY: 27 ± 8	SY: 26 ± 9	SY: 29 ± 9

Values expressed with a plus/minus sign are the mean ± standard deviation.

SCT, Sasang constitutional type; TE, Taeumin; SE, Soeumin; SY, Soyangin; SCM, Sasang constitutional medicine; SCAT, Sasang constitutional analytical tool; QSCCII, Questionnaire for the Sasang Constitution Classification II; QSCCII+, revised Questionnaire for the Sasang Constitution Classification II.

Table 3.

Studies on Prevalence Rate of Each Disease by SCT and/or Sex

			Prevalence rate (%)
Disease	Patient age (yr)	Patients (n)	Total	TE	SE	SY	p-Value ^a
Prehypertension¹³	48.0 ± 14.6	T (2806)	54.3	64.3	46.9	49.3	0.000
		M (914)	66.1^b	74.9	59.4	60.1	0.000
		F (1892)	48.6^b	58.3	41.7	44.4	0.000
General obesity¹⁴	49.4 ± 14.6	T (3348)	30.9	54.9	6.9	20.7	0.000
		M (1191)	39.2^b	62.1	7.5	30.3	0.000
		F (2157)	26.3^b	50.3	6.6	15.5	0.000
Abdominal obesity¹⁴	49.4 ± 14.6	T (3348)	39.1	62.4	16.8	28.7	0.000
		M (1191)	40.4	61.7	13.1	30.8	0.000
		F (2157)	38.4	62.9	18.4	27.5	0.000
Abdominal obesity¹⁵	51.4 ± 12.6	T (2528)	55.2	76.5	33.5	45.6	0.000
		M (909)	42.8^b	63.6	14.7	32.8	0.000
		F (1619)	62.1^b	84.8	41.7	52.8	0.000
Metabolic syndrome¹⁶	48.1 ± 14.9	T (1617)	35.4	49.8	18.0	30.6	0.000
		M (593)	35.8	49.2	13.5	33.3	0.000
		F (1024)	35.2	50.3	20.5	29.2	0.000
Metabolic syndrome¹⁷	56.0 (mean), ≥40	T (666)	35.7	51.5	15.8	19.0	0.000
		M (280)	29.3^b	40.4	14.8	21.7	0.000
		F (386)	40.4^b	59.0	16.5	16.7	0.000
Diabetes mellitus¹⁸	46.7 ± 11.8	T (1443)	7.2	11.4	1.7	5.0	0.000
		M (712)	8.7^c	11.7	4.0	6.7	0.002
		F (731)	5.7^c	11.0	0.8	2.0	0.000
Functional dyspepsia¹⁹	21 (median), 17–77 (range)	T (517)	22.2	27.5	23.1	16.4	0.055
		M (190)	14.2^b	9.1	17.3	11.3	0.389
		F (327)	26.9^b	32.5	29.5	18.8	0.049
IBS²⁰	51.8 ± 7.0	T (1362)	12.0	9.9	18.3	13.2	0.005
		M (705)	10.9	8.8	23.1	9.9	0.000
		F (657)	13.2	11.4	13.5	15.2	0.414
COPD²¹	54.8 ± 8.1	T (1544)	5.7	5.6	6.9	4.3	0.354
		M (608)	11.3^b	10.4	16.7	8.9	0.128
		F (936)	2.0^b	1.5	2.9	2.2	0.402
Osteoporosis²²	54.9 ± 8.2	T (1752)	11.2	10.4	13.9	10.6	0.149
		M (434)	9.0	6.6	15.0	7.5	0.024
		F (1318)	12.0	11.7	13.4	11.1	0.663
Alopecia²³	32.9 (mean), 20–50	M (409)	44.5	51.2	41.3	42.1	0.193
Irregular menstruation²⁴	16.5 ± 0.2	F (581)	42.9	37.8	46.3	43.6	0.283
Ovarian neoplasm¹⁰	47.3 (mean), ≥10	F (734)	1.8	1.8	2.0	1.4	0.938
Uterine fibroid¹⁰	47.3 (mean), ≥10	F (734)	9.8	10.7	9.6	8.1	0.676

Values expressed with a plus/minus sign are the mean ± standard deviation.

p-Value obtained by chi-square test for each disease's prevalence rates among SCTs in male participants, female participants, and total.

p < 0.01; obtained by chi-square test for each disease's prevalence rates between male participants and female participants.

p < 0.05; obtained by chi-square test for each disease's prevalence rates between male participants and female participants.

T, total; M, male; F, female.

Statistical analysis

A chi-square test was applied to investigate the statistical significance of the differences in the prevalence rates of disorders according to SCT and sex. A p-value ≤0.05 was considered to indicate a statistically significant difference. All statistical analyses were performed by using SPSS software, version 18.0 KO for Windows (IBM Inc., Chicago, IL).

Results

Data characteristics

From 14,272 relevant articles, 160 articles were identified in the initial screening, and 13 articles were ultimately selected for this study (Table 2). Of the 13 articles, 11 articles surveyed a single disorder, whereas 2 articles investigated 2 disorders simultaneously, resulting in 15 studies of disorders. In addition to abdominal obesity and metabolic syndrome, 11 types of disorders had a single study (Table 3).

Among the 13 disorders, 4 were sex-dependent disorders (alopecia, irregular menstruation, ovarian neoplasm, and uterine fibroid); 9 were general disorders for both sexes, including 5 metabolic syndrome–related disorders (prehypertension, general obesity, abdominal obesity, metabolic syndrome, and diabetes mellitus); 2 were gastrointestinal disorders (functional dyspepsia and irritable bowel syndrome [IBS]); and 2 were other types of disorders (chronic obstructive pulmonary disease [COPD] and osteoporosis).

Participant characteristics and SCT diagnosis

Fifteen studies involved a total of 19,307 participants (6945 male and 12,362 female participants). The average number of participants was 1485 ± 938 (male, 631 ± 298; female, 1030 ± 594), ranging from 409 to 3348 participants across 15 studies. Participant ages were diverse depending on the study, ranging from 10 to 77 years. SCT diagnosis was obtained by SCM specialists for 5 studies, SCAT for 5 studies, and QSCC II or QSCC II+ for 5 studies. The proportions of the TE, SE, and SY types were 45%, 26%, and 29%, respectively, and no significant difference was observed in sex distribution (48%, 24%, and 28% in male participants and 42%, 28%, and 30% in female participants, respectively) (Table 2).

Prevalence of each disease by SCT

The average prevalence rate across 15 studies for the TE, SE, and SY types were 35.0 ± 25.2, 20.1 ± 15.2, and 22.6 ± 16.4, respectively. Of the 15 studies, 8 studies showed a significantly different prevalence pattern according to SCT for 6 disorders (prehypertension, general obesity, abdominal obesity, metabolic syndrome, diabetes mellitus, and IBS). Among these disorders, IBS was SE-type predominant whereas the others were TE-type predominant. Functional dyspepsia and osteoporosis showed partial significance, whereas 4 sex-dependent disorders and COPD did not show significant differences in SCT-related prevalence (Table 3).

Prevalence of each disease by sex and SCT

The average prevalence across 15 studies was 27.2 ± 18.3; by sex, it was 29.3 ± 18.5 for male participants and 26.1 ± 19.1 for female participants (except for 4 sex-dependent disorders). COPD was mostly male-predominant (5.6-fold; p < 0.01), along with several other disorders (1.5-fold for general obesity and diabetes mellitus, 1.4-fold for prehypertension; p < 0.05 or p < 0.001). Functional dyspepsia (1.9-fold), as well as abdominal obesity and metabolic syndrome (1.5- and 1.4-fold, in only one study), was significantly female-predominant (p < 0.001).

When the analyses were conducted for each sex, SCT-dependent differences in prevalence were observed repeatedly in both male and female participants. In addition, no disorder showed a significantly different pattern of SCT-related prevalence between male and female participants (Table 3).

Discussion

This review revealed that SCT has an effect on the prevalence rates of various disorders, especially disorders of the circulatory and metabolic systems. SCM is a Korean-originated medical theory that formulates a customized system of diagnosis, treatment, and prevention based on 4 SCTs (TE, SE, SY, and TY). The diagnosis of SCT depends on facial structure, body shape, voice, and personality originating from a functional imbalance among the visceral organs in an individual.^35,36 This functional imbalance includes hyperactive liver function and hypoactive lung function (TE, greater yin) and vice versa (TY, greater yang), as well as hyperactive kidney function and hypoactive spleen function (SE, lesser yin) and vice versa (SY, lesser yang). As such, each pair of the four visceral organs forms a “see-saw” relationship, affecting individuals’ digestive and metabolic performance.^37,38 The spleen–kidney pair regulates nutrient metabolism, in which the hot energy of the spleen draws in food and water whereas the cold energy of the kidney sends them out. On the other hand, the liver–lung pair controls energy metabolism, in which the cooled energy of the liver converts diet into qi () and body fluid while the warmed energy of the lung expels them.³⁹ Several studies revealed a different aspect of susceptibility to disorders according to SCT, such as a more than 2-fold higher prevalence of fatty liver in TE-type individuals than in individuals of other SCTs.⁴⁰

To evaluate and characterize the influence of SCTs on the development of disorders, the authors systematically reviewed articles about disorder prevalence by SCT. To minimize bias due to small sample sizes, only studies with greater than 400 participants were included. This review showed that SCT significantly affected the prevalence rates of 6 disorders: prehypertension, general obesity, abdominal obesity, metabolic syndrome, diabetes mellitus, and IBS. Except for IBS, the other 5 disorders (prehypertension, general obesity, abdominal obesity, metabolic syndrome, and diabetes mellitus) have a TE-predominant pattern, the average prevalence rates of which were 2.7-fold and 1.9-fold higher in TE than in SE and SY, respectively. Similar TE-predominant prevalence rates in these disorders were also observed in each sex group (Table 3). The etiology and pathologic features were also closely associated with each other, which were associated with the metabolic syndrome.^41,42 These results indicated that TE would be highly susceptible to metabolic disturbances and cardiovascular disorders, a finding supported by several recent studies.

During a 10-year follow-up study involving 2839 patients, 56.4% of TE-type individuals were newly diagnosed with metabolic syndrome, followed by SY (32.3%) and SE (14.5%) individuals, respectively.⁴³ In addition, one study showed that the TE type was predominant among 493 inpatients with cerebral infarction (56.4% for TE, 9.1% for SE, and 34.1% for SY).⁴⁴ Consistent with the current results, another study showed that both hypertension and dyslipidemia were more prevalent in TE-type individuals.⁸

Recently, genome-wide association studies were performed to identify susceptible loci for common and complex diseases.⁴⁵ For example, individuals with genetic variants at the 12p13.33 locus had a greater risk for lung squamous cell carcinoma.⁴⁶ The classification of SCT is now in the process of interpretation with modern genome-wide association analysis for scientific evidence.^47,48 One group reported that the TE type is subject to higher levels of serum triglyceride but lower levels of high-density lipoprotein cholesterol, due to the 1131T>C polymorphism of APOA5, a genetic determinant of serum lipids.⁴⁹ Another study also observed that overweight TE-type women are often associated with the 889C/T polymorphism of interleukin-1α, affecting multiple neuroendocrine and metabolic functions.⁵⁰ For abdominal obesity^14,15 and metabolic syndrome,^16,17 two different groups have studied these disorders, and their findings were grossly similar.

According to SCM, SE-type individuals are prone to digestive problems because of deficient spleen function.⁵ In the current data, the SE type showed a high prevalence of IBS²⁰ (1.8- and 1.4-fold for the TE and SY types) (Table 3). Several clinical studies have reported that SE-type individuals tend to report gastrointestinal symptoms (e.g., loss of appetite, discomfort in defecation).^51,52 However, the data revealed a TE-predominant pattern for functional dyspepsia.¹⁹ Thus, further scientific evidence is needed to determine the relationship between the SE type and the digestive system. There was no significant difference in the SCT-related prevalence of 4 sex-dependent disorders: alopecia,²³ irregular menstruation,²⁴ ovarian neoplasm,¹⁰ and uterine fibroid.¹⁰ Several studies have reported a potentially sex-dependent difference in SCT-associated susceptibility in specific diseases, including cancer.⁵³ We therefore analyzed the sex difference in SCT-related prevalence, and no significant difference was observed (Table 3).

However, the current study has some limitations, including a relatively small number of participants for studying the susceptibility to disease, a lack of enrolled studies, and a wide variance in SCT distribution, which may be due to different types of SCT diagnostic criteria. Nevertheless, this review study strongly assumed the presence of SCT-associated susceptibility to specific diseases, especially metabolic syndrome–related disorders. To explain the underlying mechanisms of the different susceptibilities to specific disorders by the SCT trait, many previous studies have been performed. SCM classification is assumed to be connected to macro-level genomic differences.^54,55 In addition, there was a notably distinct profile of gut microbiota, indicating different behaviors of food intake and excretion and different biological and psychological characteristics according to SCT.^56
–58 Our study provides important insight into SCT-associated susceptibility to disorders, which is expected to be a foundation of further scientific investigation in SCM.

Conclusion

Taken together, the findings reported here suggest that SCT strongly affects the development of diseases, especially metabolic syndrome–related disorders. Further studies are needed to elucidate the concrete features of SCT-related susceptibility in the future, which may be valuable in preventive medicine using Sasang constitutional practice.

Footnotes

Acknowledgments

This research was supported by the Bio & Medical Technology Development Program of the NRF funded by the Ministry of Science, ICT & Future Planning (NRF-2014M3A9D7034335), the research program of the Korea Institute of Oriental Medicine (K16091), and the Oriental Medicine Research and Development Project, Ministry of Health and Welfare (HI15C-0112-000015), South Korea.

Author Disclosure Statement

No competing financial interests exist.

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