RESUMEN
OBJECTIVE: Previous studies have identified ethnic specific differences in visceral adipose tissue (VAT), which may account for ethnic differences in cardio-metabolic risk. However, two distinctive sub-compartments of abdominal subcutaneous adipose tissue (SAT) have been recently identified that may also differ among ethnic groups. Therefore, the relationship between SAT compartments and body fat mass (BFM) between Aboriginal, Chinese, and South Asian cohorts compared to Europeans was investigated. DESIGN AND METHODS: Healthy Aboriginal, Chinese, European, and South Asian (n = 822) men and women (30-65 years) were assessed for BFM via dual energy X-ray absorptiometry, and SAT areas using computer tomography. SAT was subdivided into superficial SAT (SSAT) and deep SAT (DSAT) via the fascia-superficialis. Linear regression was performed using DSAT and SSAT as separate dependent variables and BFM and ethnicity as primary independent variables adjusting for confounders. RESULTS: Aboriginal (181.0 cm(2) ; p = 0.045) and South Asians (178.3 cm(2) ; p = 0.013) had significantly higher amounts of DSAT, whereas the Chinese cohort had significantly less when compared with Europeans (114.3 cm(2) ; p = <0.001). The Aboriginal cohort had a significantly higher amount of SSAT than Europeans (123.13 cm(2) vs. 108.7 cm(2) ; p = 0.04). Ethnicity modified the relationship between DSAT and BFM (p < 0.001 for interaction) such that Aboriginals and majority of South Asians had a significantly greater DSAT. CONCLUSION: These data further demonstrate ethnic differences in body fat distribution such that Aboriginals and South Asians have greater amounts of DSAT. This may contribute to the increased cardio-metabolic risk in these groups.
Asunto(s)
Grasa Abdominal/patología , Adiposidad/etnología , Adulto , Anciano , Pueblo Asiatico , Etnicidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Nativos de Hawái y Otras Islas del Pacífico , Obesidad/etnología , Grasa Subcutánea/patología , Población BlancaRESUMEN
South Asians have a higher risk for cardiovascular disease (CVD) that remains largely unexplained. We hypothesized that the increased CVD risk in South Asians compared to Europeans is mediated through higher levels of visceral adipose tissue (VAT) in South Asians compared to total body fat and subcutaneous abdominal adipose tissue (SAT). South Asians (207) and Europeans (201) underwent assessment for demographics, body fat, and risk factors. Linear regression models were created by sex for each risk factor to explore mediation effects of total body fat, SAT, and VAT adjusted for age, income, smoking, and BMI (menopausal status for women). Mediation was based on changes in the ethnicity ß coefficient due to additional adjustment for our adipose variable of interest and the Sobel test for mediation. South Asians had worse lipid, glucose, insulin, and C-reactive protein (CRP) levels than Europeans after adjusting for confounders. Most of these differences remained even after further adjustment by either total body fat or SAT. In contrast, VAT attenuated the ethnic differences in risk factors by 16%-52%. After adjusting for VAT, there were no longer ethnic differences in total cholesterol (TC), LDL-C, TC/HDL-C, glucose, and diastolic blood pressure (BP) in men, and in HDL-C, triglycerides (TG), TC/HDL-C, and homeostasis model (HOMA) in women, and VAT was a significant mediator for these risk factors. Higher levels of risk factors for CVD in South Asians are predominantly because of the unique phenotype of South Asians having greater VAT than Europeans even at the same BMI.
Asunto(s)
Pueblo Asiatico , Enfermedades Cardiovasculares/epidemiología , Diabetes Mellitus Tipo 2/epidemiología , Grasa Intraabdominal/patología , Obesidad/sangre , Grasa Subcutánea Abdominal/patología , Población Blanca , Absorciometría de Fotón , Glucemia/metabolismo , Composición Corporal/genética , Índice de Masa Corporal , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/genética , HDL-Colesterol/sangre , Estudios de Cohortes , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/genética , Femenino , Genotipo , Humanos , Lípidos/sangre , Masculino , Persona de Mediana Edad , Obesidad/epidemiología , Obesidad/genética , Fenotipo , Factores de Riesgo , Clase Social , Triglicéridos/sangreRESUMEN
South Asians have a higher prevalence of cardiovascular disease (CVD) than Europeans. Studies have identified distinct subcompartments of subcutaneous adipose tissue (SAT) that provide insight into the relationship between abdominal obesity and metabolic risk factors in different ethnic groups. Our objective was to determine the relationship between SAT compartments and fat-free mass (FFM) between South Asian and European cohorts, and between men and women. Healthy Europeans and South Asians (n = 408) were assessed for FFM via dual energy X-ray absorptiometry, and SAT areas by computed tomography (CT). SAT was subdivided into superficial subcutaneous abdominal adipose tissue (SSAT) and deep subcutaneous abdominal adipose tissue (DSAT). Linear regression analyses were performed using DSAT and SSAT as separate dependent variables and FFM and ethnicity as primary independent variables adjusting for age, gender, income, education, and smoking status. Results showed that South Asian men had significantly higher amounts of DSAT (median 187.65 cm(2) vs. 145.15 cm(2), P < 0.001), SSAT (median 92.0 cm(2) vs. 76.1 cm(2), P = 0.046), and body fat mass (BFM) (25.1 kg vs. 22.6 kg, P = 0.049) than European men. In a fully adjusted model, South Asians showed significantly greater DSAT at any FFM than Europeans. Women had more SSAT at any given FFM than men and less DSAT at any given FFM than men, irrespective of ethnic background. In conclusion, South Asians had more DSAT than Europeans and men had relatively more DSAT than women. These data suggest that specific fat depots are influenced by ethnicity and gender; therefore, could provide insight into the relationship between ethnicity, gender and subsequent risk for CVD.
Asunto(s)
Pueblo Asiatico , Distribución de la Grasa Corporal , Compartimentos de Líquidos Corporales , Obesidad Abdominal/etnología , Grasa Subcutánea Abdominal , Población Blanca , Absorciometría de Fotón , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis de Regresión , Factores Sexuales , Grasa Subcutánea Abdominal/diagnóstico por imagenRESUMEN
CONTEXT: Body fat distribution varies among different ethnic groups, yet less is known regarding differences in lean mass and how this may affect insulin resistance. OBJECTIVE: Our objective was to compare total body fat to lean mass ratio (F:LM) in Aboriginal, Chinese, European, and South Asian individuals with differences in insulin resistance. PARTICIPANTS, DESIGN, AND SETTING: Aboriginal (196), Chinese (222), European (202), and South Asian (208) individuals were recruited across a range of body mass index to participate in this cross-sectional community study. MAIN OUTCOME MEASURES: Total body fat, lean mass, and insulin resistance were assessed using homeostasis model assessment (HOMA). RESULTS: After adjustment for confounders and at a given body fat, South Asian men had less lean mass than Aboriginal [3.42 kg less; 95% confidence interval (CI) = 1.55-5.29], Chinese (3.01 kg less; 95% CI = 1.33-4.70), and European (3.57 kg less; 95% CI = 1.82-5.33) men, whereas South Asian women had less lean mass than Aboriginal (1.98 kg less; 95% CI = 0.45-3.50), Chinese (2.24 kg less; 95% CI = 0.81-3.68), and European (2.97 kg less; 95% CI = 1.67-4.27) women. In adjusted models, F:LM was higher in South Asian compared with Chinese and European men and higher in South Asian compared with Aboriginal, Chinese, and European women (P < 0.01 for all). Insulin and HOMA were greatest in South Asians after adjustment; however, these differences were no longer apparent when F:LM was considered. CONCLUSIONS: South Asians have a phenotype of high fat mass and low lean mass, which may account for greater levels of insulin and HOMA compared with other ethnic groups.
Asunto(s)
Tejido Adiposo/fisiología , Composición Corporal/fisiología , Etnicidad , Resistencia a la Insulina/fisiología , Adulto , Factores de Edad , Antropometría , Asia Sudoriental/etnología , Pueblo Asiatico , Canadá , China/etnología , Femenino , Humanos , Indígenas Norteamericanos , Insulina/sangre , Estilo de Vida , Masculino , Persona de Mediana Edad , Análisis de Regresión , Factores Sexuales , Factores Socioeconómicos , Población BlancaRESUMEN
Previously determined predictive equations for body fat mass (BFM) are primarily derived from populations of European origin, which may not be appropriate for all ethnic groups. The objective of this study was to develop an improved predictive equation for BFM specific to South Asians and derived from common anthropometric measurements that include measures of central adiposity. A total of 208 apparently healthy South Asian men and women, aged 30-65 years, were recruited. Anthropometric measurements and BFM by dual energy X-ray absorbitometry (DEXA) were obtained. Sex-specific equations predicting BFM were developed using regression models on a reference subset (68 men, 70 women) and tested on a validation group. New predictive equations (BFMNEW) were tested for agreement with Durin and Wormersley and Siri equations and with the reference method, DEXA. The best predictive sex-specific equation involved a combination of skinfolds, waist circumference, hip circumference, humerus breadth, height, mass, and age. Models significantly correlated with BFM determined by DEXA (r = 0.946 for men; r = 0.974 for women; p < 0.001). The estimates of BFM from reference and validation groups had excellent correlations and displayed excellent agreement to DEXA measures. We demonstrated new predictive equations for BFM that are specific to South Asians and incorporate measures of central adiposity. This may help resolve issues surrounding inaccurate determination of adiposity in South Asians, and consequently provide better estimations of disease risk.
Asunto(s)
Adiposidad/etnología , Pueblo Asiatico , Modelos Biológicos , Absorciometría de Fotón , Adulto , Factores de Edad , Anciano , Asia , Pueblo Asiatico/estadística & datos numéricos , Estatura , Peso Corporal , Femenino , Humanos , Húmero/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Análisis de Regresión , Reproducibilidad de los Resultados , Factores Sexuales , Grosor de los Pliegues Cutáneos , Circunferencia de la CinturaRESUMEN
OBJECTIVE: To compare the prediction of percentage body fat using BMI and visceral adipose tissue (VAT) using waist circumference (WC) in individuals of Chinese, European, and South Asian origin. RESEARCH METHODS AND PROCEDURES: Healthy men and women of Chinese, European, and South Asian origin (n = 627) between the ages of 30 and 65 years were recruited to ensure equal distribution of gender and representation across BMI ranges (18.5 to 24.9, 25 to 29.9, and >or=30 kg/m(2)). Participants were assessed for demographics, anthropometry, lifestyle, and regional adiposity. Percentage body fat and VAT were measured by DXA and computer tomography scan, respectively. RESULTS: BMI and WC were highly correlated with total and regional measures of adiposity in each ethnic group. At any BMI, the percentage body fat of Chinese participants was similar to that of Europeans, but that of South Asians was greater by 3.9% (p < 0.001). Above a WC of 71.0 cm, the Chinese participants had an increasingly greater amount of VAT than the Europeans (p = 0.017 for interaction). South Asians had significantly more VAT than the Europeans at all but the most extreme WC (above 105 cm) (p < 0.05). DISCUSSION: Compared with Europeans, percentage body fat was higher for a given BMI in South Asians, whereas VAT was higher for a given WC in both Chinese and South Asian men and women. These findings support the use of ethnic-specific anthropometric targets.
Asunto(s)
Tejido Adiposo/patología , Adiposidad/etnología , Índice de Masa Corporal , Grasa Intraabdominal/patología , Relación Cintura-Cadera , Adulto , Anciano , Antropometría , Pueblo Asiatico , Composición Corporal , Femenino , Encuestas Epidemiológicas , Humanos , Estilo de Vida/etnología , Masculino , Persona de Mediana Edad , Población BlancaRESUMEN
BACKGROUND: It was suggested that body fat distribution differs across ethnic groups, and this may be important when considering risk of disease. Previous studies have not adequately investigated differences in discrete regions of abdominal adiposity across ethnic groups. OBJECTIVE: We compared the relation between abdominal adipose tissue and total body fat between persons living in Canada of Aboriginal, Chinese, and South Asian origin with persons of European origin. DESIGN: Healthy Aboriginal, Chinese, European, and South Asian participants (n = 822) aged between 30 and 65 y were matched by sex, ethnicity, and body mass index (BMI; in kg/m(2)) range. Total abdominal adipose tissue (TAT), subcutaneous abdominal adipose tissue (SAT), visceral adipose tissue (VAT), total body fat mass, lifestyle, and demographics were assessed. Relations between BMI and total body fat, TAT, SAT, and VAT and between total body fat and TAT, SAT, and VAT were investigated. RESULTS: BMI significantly underestimated VAT in all non-European groups. Throughout a range of total body fat mass, VAT was not significantly different between the Aboriginals and the Europeans. With total body fat >9.1 kg, Chinese participants had increasingly greater amounts of VAT than did the Europeans (P for interaction = 0.008). South Asians had less VAT with total body fat >37.4 kg but more VAT below that amount than did Europeans (P for interaction < 0.001). CONCLUSION: Compared with Europeans, the Chinese and South Asian cohorts had a relatively greater amount of abdominal adipose tissue, and this difference was more pronounced with VAT. No significant differences were observed between the Aboriginals and the Europeans.
Asunto(s)
Tejido Adiposo/anatomía & histología , Composición Corporal , Adulto , Anciano , Indio Americano o Nativo de Alaska , Pueblo Asiatico , Índice de Masa Corporal , Colombia Británica , Demografía , Etnicidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Selección de Paciente , Vísceras , Población BlancaRESUMEN
BACKGROUND AND PURPOSE: The association between abdominal obesity and atherosclerosis is believed to be due to excess visceral adipose tissue (VAT), which is associated with traditional risk factors. We hypothesized that VAT is an independent risk factor for atherosclerosis. METHODS: Healthy men and women (N=794) matched for ethnicity (aboriginal, Chinese, European, and South Asian) and body mass index range (<25, 25 to 29.9, or > or =30 kg/m(2)) were assessed for VAT (by computed tomography scan), carotid atherosclerosis (by ultrasound), total body fat, cardiovascular risk factors, lifestyle, and demographics. RESULTS: VAT was associated with carotid intima-media thickness (IMT), plaque area, and total area (IMT area and plaque area combined) after adjusting for demographics, family history, smoking, and percent body fat in men and women. In men, VAT was associated with IMT and total area after adjusting for insulin, glucose, homocysteine, blood pressure, and lipids. This association remained significant with IMT after further adjustment for either waist circumference or the waist-to-hip ratio. In women, VAT was no longer associated with IMT or total area after adjusting for risk factors. CONCLUSIONS: VAT is the primary region of adiposity associated with atherosclerosis and likely represents an additional risk factor for carotid atherosclerosis in men. Most but not all of this risk can be reflected clinically by either the waist circumference or waist-hip ratio measures.