Racial differences in abdominal depot-specific adiposity in white and African American adults

Hepatic steatosis and cardiovascular disease outcomes: An analysis of the Framingham Heart Study

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is highly prevalent and is associated with development of metabolic disease including atherosclerotic cardiovascular disease (CVD). Our aim is to examine the association of hepatic steatosis with prevalent clinical and subclinical CVD outcomes in a large community-based sample, the Framingham Heart Study.

METHODS

Hepatic steatosis was measured in 3529 participants using multidetector computed tomography scanning. Multivariable logistic regression was used to determine whether hepatic steatosis is associated with prevalent CVD adjusted for covariates. We also tested whether associations were independent of other metabolic diseases/traits. The primary clinical outcome was composite prevalent clinical CVD defined by prior non-fatal myocardial infarction, stroke, transient ischemic attack, heart failure, or peripheral arterial disease. Subclinical cardiovascular outcomes were coronary artery calcium (CAC) and abdominal artery calcium (AAC).

RESULTS

3014 participants were included (50.5% women). There was a non-significant association of hepatic steatosis with clinical CVD (OR 1.14 [p=0.07]). Hepatic steatosis was associated with both CAC and AAC (OR 1.20 [p<0.001] and OR 1.16 [p<0.001], respectively). Associations persisted for CAC even when controlling for other risk factors/metabolic diseases, but for AAC, the associations became non-significant after adjustment for visceral adipose tissue. The association between hepatic steatosis and AAC was stronger in men than in women (p sex interaction=0.022).

CONCLUSION

There was a significant association of hepatic steatosis with subclinical CVD outcomes independent of many metabolic diseases/traits with a trend towards association between hepatic steatosis and clinical CVD outcomes. The association with AAC was stronger in men than in women.

Inflammation as a Mediator of the Association Between Race and Atrial Fibrillation: Results from the Health, Aging, and Body Composition Study

BACKGROUND

Despite a lower prevalence of established atrial fibrillation (AF) risk factors, Whites exhibit substantially higher rates of this arrhythmia compared to Blacks. The mechanism underlying this observation is not known. Both inflammation and obesity are risk factors for AF, and adipose tissue is a known contributor to systemic inflammation.

OBJECTIVES

We sought to determine the degree to which racial differences in AF risk are explained by differences in inflammation and adiposity.

METHODS

Baseline serum inflammatory biomarker concentrations and abdominal adiposity (assessed by computed tomography) were quantified in a subset of Black and White participants without prevalent AF in the Health, Aging, and Body Composition (Health ABC) Study. Participants were prospectively followed for the diagnosis of AF using study ECGs and Medicare claims data. Cox proportional hazards models were used to determine the adjusted relative hazard of incident AF between races before and after biomarker adjustment.

RESULTS

Among 2,768 participants (43% Black), 721 developed incident AF over a median follow up of 10.9 years. White race was associated with a heightened adjusted risk of incident AF (HR 1.55, 95% CI 1.30 to 1.84, p < 0.001). Abdominal adiposity was not associated with AF when added to the adjusted model. Among the studied biomarkers, adiponectin, TNF-α, TNF-α SR I, and TNF-α SR II concentrations were each higher among Whites and independently associated with a greater risk of incident AF. Together, these inflammatory cytokines mediated 42% (95% CI 15 to 119%, p = 0.004) of the adjusted race-AF association.

CONCLUSIONS

Systemic inflammatory pathways significantly mediate the heightened risk of AF among Whites. The higher level of systemic inflammation and concomitant increased AF risk in Whites is not explained by racial differences in abdominal adiposity or the presence of other pro-inflammatory cardiovascular comorbidities.

The Interplay Between Sex, Ethnicity, and Adipose Tissue Characteristics

The obesity epidemic in the USA affects disproportionately women and the ethnic minorities. On the other hand, female sex is traditionally associated with a favorable fat distribution preferentially in the subcutaneous depots of the lower body and with improved endocrine and metabolic function of the adipose tissue. However, these data are derived from predominantly non-Hispanic white populations. This review discusses fat distribution patterns in women of diverse ethnic backgrounds, together with data on the release of adipokines from adipose tissue in these populations. Very little information is available on how the metabolic function of the adipocyte differs depending on ethnicity. Thus, it becomes clear that future clinical and translational research should explicitly discuss and take into account the sex and ethnic background of the populations studied.

Race differences in obesity and its relationship to the sex hormone milieu

A sexual dimorphism exists in which increased abdominal and visceral adipose tissue (VAT) - found in women and marked by low sex hormone binding globulin (SHBG) and high bioavailable testosterone (BT) - is related to the metabolic risk profile. In men, increased BT is related to decreased abdominal obesity and a decrease in the metabolic risk profile. In women, race differences have been found in androgenic sex steroids including SHBG and BT as well as central fat distribution, creating inherently greater metabolic risk for certain populations. Estrogen and estrogen receptor isoforms play a role in fat deposition and distribution and may influence the changes that occur during the menopausal transition. Androgenic sex steroids serve a mediating role, influencing VAT accumulation and its associated metabolic risk factors while VAT also serves a mediating role influencing the androgenic sex steroid-metabolic risk relationship in women. Furthermore, androgenic sex steroids and VAT may independently contribute to the variance in several metabolic variables associated with cardiovascular disease, type 2 diabetes, and their antecedent conditions such as the metabolic syndrome. Race has been shown to modify the relationship between androgenic sex steroids and metabolic variables associated with risk for diabetes in Black and White women. Further research is warranted to examine the mechanisms involved in race differences. Total adiposity and central fat distribution in accordance with changes in the hormone and metabolic milieu influence breast cancer risk, which varies by race and menopausal status. These findings have broader implications for the study of health promotion/disease prevention in women.

A randomized controlled exercise training trial on insulin sensitivity in African American men: The ARTIIS study: Major category: study design, statistical design, study protocols

BACKGROUND

Lack of regular physical activity at prescribed intensity levels is a modifiable risk factor for insulin resistance and the development of diabetes. African American men are at increased risk for developing diabetes and most African American men are not meeting the current recommended levels of physical activity. The primary objective of the Aerobic Plus Resistance Training and Insulin Resistance in African American Men (ARTIIS) study is to determine the effectiveness of an exercise training intervention aimed at reducing diabetes risk factors in African American men at risk for developing diabetes.

METHODS

Insufficiently active 35-70 year old African American men with a family history of diabetes were eligible for the study. The 5-month randomized controlled trial assigns 116 men to an exercise training or healthy living control arm. The exercise training arm combines aerobic and resistance training according to the current national physical activity recommendations and is conducted in community (YMCA) facilities. The healthy living arm receives information promoting healthy lifestyle changes.

OUTCOMES

Insulin response to an oral glucose load is the primary outcome measure, and changes in physiological parameters, cardiorespiratory fitness, strength, body composition, and psychological well-being comprise the secondary outcomes.

CONCLUSIONS

The ARTIIS study is one of the first adequately powered, rigorously designed studies to investigate the effects of an aerobic plus resistance exercise training program and to assess adherence to exercise training in community facilities, in African American men.

Saturated fatty acids in human visceral adipose tissue are associated with increased 11- β-hydroxysteroid-dehydrogenase type 1 expression

Background

Visceral fat accumulation is associated with metabolic disease. It is therefore relevant to study factors that regulate adipose tissue distribution. Recent data shows that overeating saturated fatty acids promotes greater visceral fat storage than overeating unsaturated fatty acids. Visceral adiposity is observed in states of hypercortisolism, and the enzyme 11-β-hydroxysteroid-dehydrogenase type 1 (11β-hsd1) is a major regulator of cortisol activity by converting inactive cortisone to cortisol in adipose tissue. We hypothesized that tissue fatty acid composition regulates body fat distribution through local effects on the expression of 11β-hsd1 and its corresponding gene (HSD11B1) resulting in altered cortisol activity.

Findings

Visceral- and subcutaneous adipose tissue biopsies were collected during Roux-en-Y gastric bypass surgery from 45 obese women (BMI; 41 ± 4 kg/m²). The fatty acid composition of each biopsy was measured and correlated to the mRNA levels of HSD11B1. 11β-hsd1 protein levels were determined in a subgroup (n = 12) by western blot analysis. Our main finding was that tissue saturated fatty acids (e.g. palmitate) were associated with increased 11β-hsd1 gene- and protein-expression in visceral but not subcutaneous adipose tissue.

Conclusions

The present study proposes a link between HSD11B1 and saturated fatty acids in visceral, but not subcutaneous adipose tissue. Nutritional regulation of visceral fat mass through HSD11B1 is of interest for the modulation of metabolic risk and warrants further investigation.

Adolescent oligomenorrhea (age 14-19) tracks into the third decade of life (age 20-28) and predicts increased cardiovascular risk factors and metabolic syndrome

OBJECTIVE

Assess whether adolescent oligomenorrhea (age 14-19) tracks into young adulthood (age 20-28) and predicts increased cardiometabolic risk factors, metabolic syndrome (MetS), and impaired fasting glucose-type II diabetes mellitus (IFG+T2DM).

MATERIALS AND METHODS

Prospective study of menstrual cyclicity and its metabolic effects in 865 black and white schoolgirls from age 9 to 19, and 605 of these 865 girls from age 20 to 28.

MAIN FINDINGS

Patterns of menstrual delays (oligomenorrhea) during ages 14-19 and ages 20-28 were closely related (p<.0001). Adolescent menses delay (ages 14-19, p<.0001), mean insulin (ages 20-28, p=.0003), and self-identified polycystic ovary syndrome (PCOS, p=.049) predicted ages 20-28 menses delay. Menses delays during ages 14-19 and 20-28, and, their interaction product were correlated with IFG+T2DM and MetS at ages 20-28. Waist circumference (ages 20-28, p<.0001), mean triglyceride (ages 20-28, p=.005), and the number of average menstrual cycles≥42 days (ages 20-28, p=.04) predicted IFG+T2DM (ages 20-28). MetS (ages 9-19, p<.0001), mean insulin (ages 20-28, p=.0002), the number of ≥42 day gaps between menstrual periods (ages 20-28, p=.02), and cigarette smoking at age 18-19 (p=.04) were significant explanatory variables for MetS at ages 27-28. As MetS status category changed from age 14-19 to 27-28 from best to worst: (no → no), (yes → no), (yes → yes), (no → yes), the number of women with ≥2 menses delays during ages 20-28 rose from 3% to 4% to 15% to 17%, p=.0001. MetS status change from age 9-19 to 27-28 was positively associated with mean insulin (age 20-28, p<.0001), cigarette smoking (age 24-25, p=.01) and the number of menses delays during ages 20-28 (p=.04).

PRINCIPAL CONCLUSIONS

Menstrual patterns track from adolescence to young adulthood, and oligomenorrhea predicts MetS and IFG+T2DM. Patterns of menses delays in adolescence should be considered as a significant risk factor for future development of young adult IFG+T2DM, MetS, oligomenorrhea, and polycystic ovary syndrome.

Adolescent and young adult female determinants of visceral adipose tissue at ages 26-28 years

OBJECTIVE

To assess adolescent and young adult determinants of visceral adipose tissue (VAT) at ages 26-28 years.

STUDY DESIGN

Prospective study (ages 9-28 years) of cardiometabolic measures, menarche age, menses irregularities, metabolic syndrome, impaired fasting glucose-type 2 diabetes mellitus, and VAT in 400 girls (248 black, 152 white).

RESULTS

Adolescent (age 14-19) independent variables for greater VAT at ages 26-28 included larger mean waist circumference (partial R(2) = 30.8%), earlier age at menarche (0.9%), and white race (1.8%). Young adult (ages 20-28 years) independent variables for greater VAT included larger mean waist circumference (partial R(2) = 61.7%), greater triglyceride levels (3.3%), lower high-density lipoprotein cholesterol (1.0%), and greater insulin resistance (homeostasis model assessment-estimated insulin resistance; 0.4%). Independent variables for greater VAT when both adolescent and young adult variables were used included waist (tertile rank change from adolescence to young adulthood, partial R(2) = 58.3%), greater young adult triglyceride levels (4.4%), white race (1.8%), greater young adult homeostasis model assessment-estimated insulin resistance (age 20-28, 2.4%), and earlier menarche age (0.7%). Menses irregularities were not independently associated with young adult VAT.

CONCLUSIONS

Adolescent girls with early menarche and larger waist circumference should be targets for primary prevention of accretion of VAT. In young adulthood, VAT is associated with dysregulated cardiometabolic profiles, which is greater for those with waist circumference increases from adolescence to adulthood. Waist circumference during young adulthood, and to a lesser degree during adolescence, is an inexpensive surrogate for VAT at ages 26-28 years.

Obesity, body fat distribution, and risk of breast cancer subtypes in African American women participating in the AMBER Consortium

African American (AA) women are more likely than white women to be obese and to be diagnosed with ER- and triple-negative (TN) breast cancer, but few studies have evaluated the impact of obesity and body fat distribution on breast cancer subtypes in AA women. We evaluated these associations in the AMBER Consortium by pooling data from four large studies. Cases were categorized according to hormone receptor status as ER+, ER-, and TN (ER-, PR-, and HER2-) based on pathology data. A total of 2104 ER+ cases, 1070 ER- cases (including 491 TN cases), and 12,060 controls were included. Odds ratios (OR) and 95 % confidence intervals (CI) were computed using logistic regression, taking into account breast cancer risk factors. In postmenopausal women, higher recent (most proximal value to diagnosis/index date) BMI was associated with increased risk of ER+ cancer (OR 1.31; 95 % CI 1.02-1.67 for BMI ≥ 35 vs. <25 kg/m(2)) and with decreased risk of TN tumors (OR 0.60; 95 % CI 0.39-0.93 for BMI ≥ 35 vs. <25). High young adult BMI was associated with decreased premenopausal ER+ cancer and all subtypes of postmenopausal cancer, and high recent waist-to-hip ratio with increased risk of premenopausal ER+ tumors (OR 1.35; 95 % CI 1.01-1.80) and all tumor subtypes combined in postmenopausal women (OR 1.26; 95 % CI 1.02-1.56). The impact of general and central obesity varies by menopausal status and hormone receptor subtype in AA women. Our findings imply different mechanisms for associations of adiposity with TN and ER+ breast cancers.

Changes in body composition over 8 years in a randomized trial of a lifestyle intervention: the look AHEAD study

OBJECTIVE

To determine the effects of an intensive lifestyle intervention versus a comparison group on body composition in obese or overweight persons with type 2 diabetes at baseline and at 1, 4, and 8 years.

METHODS

Body composition was measured by dual-energy X-ray absorptiometry in a subset of 1019 Look AHEAD study volunteers randomized to intervention or comparison groups. The intervention was designed to achieve and maintain ≥7% weight loss through increased physical activity and reduced caloric intake. The comparison group received social support and diabetes education.

RESULTS

At 1 year, the intervention group lost fat (5.6 ± 0.2 kg) and lean mass (2.3 ± 0.1 kg) but regained fat (∼100%) and lost lean mass between years 1 and 8. Between baseline and year 8, weight loss was greater in intervention versus comparison groups (4.0 ± 0.4 vs. 2.3 ± 0.4 kg); comparison group weight loss was mostly lean mass (2.1 ± 0.17 kg). Fat mass in the intervention group was lower than that of the comparison group at all post-baseline time points.

CONCLUSIONS

Reduced fat mass may place the intervention group at a lower risk of obesity-linked sequelae, a hypothesis that can be tested by future studies of this cohort.

Visceral fat area is associated with a high risk for early postoperative recurrence in Crohn's disease

AIM

Mesenteric hypertrophy has been recognized as an indicator of the complicated course of Crohn's disease. The aim of this study was to investigate whether the visceral fat area (VFA) is associated with postoperative clinical and endoscopic recurrence.

METHOD

Computed tomography was used to measure the subcutaneous fat area and VFA, and the mesenteric fat index (MFI) was defined as the ratio of the VFA to the subcutaneous fat area. Associations between body mass index, subcutaneous fat area, VFA and MFI and postoperative clinical and endoscopic recurrence were investigated.

RESULTS

The factors associated with postoperative endoscopic recurrence at 6 months after surgery were a high VFA value (P = 0.019) and MFI values above the median (P = 0.008). VFA values were significantly correlated with endoscopic recurrence (r = 0.895, P = 0.040) and endoscopic lesions (r = 0.617, P < 0.0001). Additionally, MFI values correlated well with endoscopic recurrence (r = 0.918, P = 0.02) and endoscopic scores (r = 0.584, P < 0.0001). Multivariate analysis indicated that VFA values above the median (hazard ratio 2.63, 95% CI 1.03-6.74) were predictive of postoperative clinical recurrence in Crohn's disease.

CONCLUSION

A high VFA value is associated with postoperative recurrence of Crohn's disease and has clinical implications with respect to optimizing prophylaxis for each individual. However, further studies are needed to confirm the predictive role of this biomarker in a different data set.

Uncovering physiological mechanisms for health disparities in type 2 diabetes

Type 2 diabetes (T2D) prevalence in the United States is significantly higher in African Americans vs Whites. Yet, the physiological mechanisms contributing to this health disparity have been poorly described. To design effective strategies to reduce this disparity, there is a need to determine whether racial differences in diabetes prevalence are attributable to modifiable or non-modifiable factors. This review synthesizes and critically evaluates the potential physiological and genetic mechanisms that may contribute to the higher susceptibility of African Americans to T2D. These mechanisms include: 1) obesity and fat distribution; 2) metabolic flexibility; 3) muscle physiology; 4) energy expenditure and fitness; and 5) genetics. We focus on the clinical significance of findings and limitations of the recent literature.

Specific cut-off points for waist circumference and waist-to-height ratio as predictors of cardiometabolic risk in Black subjects: a cross-sectional study in Benin and Haiti

PURPOSE

Waist circumference (WC) and waist-to-height ratio (WHtR) are widely used as indicators of abdominal adiposity and the cut-off values have been validated primarily in Caucasians. In this study we identified the WC and WHtR cut-off points that best predicted cardiometabolic risk (CMR) in groups of African (Benin) and African ancestry (Haiti) Black subjects.

METHODS

This cross-sectional study included 452 apparently healthy subjects from Cotonou (Benin) and Port-au-Prince (Haiti), 217 women and 235 men from 25 to 60 years. CMR biomarkers were the metabolic syndrome components. Additional CMR biomarkers were a high atherogenicity index (total serum cholesterol/high density lipoprotein cholesterol ≥4 in women and ≥5 in men); insulin resistance set at the 75th percentile of the calculated Homeostasis Model Assessment index (HOMA-IR); and inflammation defined as high-sensitivity C-reactive protein (hsCRP) concentrations between 3 and 10 mg/L. WC and WHtR were tested as predictors of two out of the three most prevalent CMR biomarkers. Receiver operating characteristic (ROC) curves, Youden's index, and likelihood ratios were used to assess the performance of specific WC and WHtR cut-offs.

RESULTS

High atherogenicity index (59.5%), high blood pressure (23.2%), and insulin resistance (25% by definition) were the most prevalent CMR biomarkers in the study groups. WC and WHtR were equally valid as predictors of CMR. Optimal WC cut-offs were 80 cm and 94 cm in men and women, respectively, which is exactly the reverse of the generic cut-offs. The standard 0.50 cut-off of WHtR appeared valid for men, but it had to be increased to 0.59 in women.

CONCLUSION

CMR was widespread in these population groups. The present study suggests that in order to identify Africans with high CMR, WC thresholds will have to be increased in women and lowered in men. Data on larger samples are needed.

Racial differences in obesity measures and risk of colorectal adenomas in a large screening population

Obesity is an important risk factor for colorectal neoplasia; however, little research exists on racial differences in obesity measures [body mass index (BMI), waist circumference (WC), and waist-hip-ratio (WHR)] associated with adenoma. We used data from the Diet and Health Studies, Phases III-V to examine differences in the contribution of obesity measures to adenoma risk by race. The sample consisted of 2184 patients (1806 white, 378 African American) undergoing outpatient colonoscopy for average risk screening. Covariates included demographics, health history, and validated measures of diet and physical activity. Among whites, BMI [overweight: odds ratio (OR) = 1.31, 95% confidence interval (CI), 1.00-1.71; obese: OR = 1.89, 95% CI, 1.41-2.56), WC (OR = 1.47, 95% CI, 1.09-1.99), and WHR (OR = 1.60, 95% CI, 1.24-2.06) were associated with adenomas. BMI was not associated with adenomas in African Americans. Although the CIs were wide, the point estimates for WHR (OR = 1.07, 95% CI, 0.51-2.22) and WC (OR = 1.04, 95% CI, 0.56-1.92) were slightly elevated above the null. BMI was associated with adenomas only among whites, whereas WHR and WC appeared to be important risk factors among both races. Racial differences in adenoma risk may be due to differences in body shape and weight and/or fat distribution.

DXA-measured visceral adipose tissue predicts impaired glucose tolerance and metabolic syndrome in obese Caucasian and African-American women

BACKGROUND/OBJECTIVES

New methods to measure visceral adipose tissue (VAT) by dual-energy X-ray absorptiometry (DXA) may help discern sex, race and phenotype differences in the role of VAT in cardiometabolic risk. This study was designed (1) to compare relationships of DXA-VAT, anthropometric and body composition variables with cardiometabolic risk factors in obese women; (2) to determine which variables most robustly predict impaired glucose tolerance (IGT) and metabolic syndrome (MetSx); and (3) to determine thresholds for DXA-VAT by race.

SUBJECTS/METHODS

VAT mass (g) and volume (cm(3)) were measured in 229 obese (body mass index (BMI), 30-49.9) women aged 21-69 years of European-American (EA=123) and African-American (AA=106) descent using the CoreScan algorithm on a Lunar iDXA scanner. Linear regression modeling and areas under the curve (AUC of ROC (receiver operating characteristic) curves) compared relationships with cardiometabolic risk. Bootstrapping with LASSO (least absolute shrinkage and selection operator) regression modeling determined thresholds and predictors of IGT and MetSx.

RESULTS

DXA-VAT explained more of the variance in triglycerides, blood pressure, glucose and homeostatic model assessment-insulin resistance (HOMA-IR) compared with anthropometric and other body composition variables. DXA-VAT also had the highest AUC for IGT (0.767) and MetSx (0.749). Including race as a variable and the interaction between VAT and race in modeling did not significantly change the results. Thresholds at which the probability of developing IGT or MetSx was⩾50% were determined separately for AA women (IGT: 2120 cm(3); MetSx: 1320 cm(3)) and EA women (IGT: 2550 cm(3); MetSx: 1713 cm(3)). The odds for IGT or MetSx were fourfold greater with each standard deviation increase in DXA-VAT.

CONCLUSIONS

DXA-VAT provides robust clinical information regarding cardiometabolic risk in AA and EA obese women and offers potential utility in the risk reduction interventions.

Relationship between epicardial adipose tissue, coronary artery disease and adiponectin in a Mexican population

Background

The amount of epicardial adipose tissue (EAT) around the heart has been identified as an independent predictor of coronary artery disease (CAD), potentially through local release of inflammatory cytokines. Ethnic differences have been observed, but no studies have investigated this relationship in the Mexican population. The objective of the present study was to evaluate whether a relationship exist between EAT thickness assessed via echocardiography with CAD and adiponectin levels in a Mexican population.

Methods

We studied 153 consecutive patients who underwent coronary angiography and transthoracic echocardiography (TTE). EAT thickness on the free wall of the right ventricle was measured at the end of systole from parasternal long and short axis views of three consecutive cardiac cycles. Coronary angiograms were analyzed for the presence, extent and severity of CAD. Serum adiponectin, lipids, glucose, C-reactive protein and fibrinogen were determined.

Results

EAT thickness was greater in patients with CAD than in those without CAD from both parasternal long (5.39 ± 1.75 mm vs 4.00 ± 1.67 mm p < 0.0001) and short-axis views (5.23 ± 1.67 vs 4.12 ± 1.77, p = 0.001). EAT thickness measured from parasternal long and short-axis showed a statistically significant positive correlation with age (r = 0.354, p < 0.001; r = 0.286, p < 0.001 respectively), and waist circumference (r = 0.189, p = 0.019; r = 0.217, p = 0.007 respectively). A significant negative correlation between EAT thickness from the parasternal long axis with cholesterol-HDL was observed (r = -0.163, p = 0.045). No significant correlation was found between epicardial fat thickness and serum adiponectin or with the severity of CAD.

Conclusions

EAT thickness was greater in patients with CAD. However, no correlation was observed with the severity of the disease or with serum adiponectin levels. EAT thickness measured by echocardiography might provide additional information for risk assessment and prediction of CAD.

Influence of exclusive enteral nutrition therapy on visceral fat in patients with Crohn's disease

BACKGROUND

Mesenteric fat plays an important role in the pathogenesis of Crohn's disease (CD), and a higher ratio of visceral fat area (VFA) to subcutaneous fat area (SFA) is related to complicated disease status. Exclusive enteral nutrition (EEN) is an effective treatment option for patients with CD, and the aims of this study were to assess the effects of EEN on abdominal fat in patients with CD.

METHODS

Patient data were obtained from a prospectively maintained database. The SFA and VFA were measured in 38 patients with CD before and after 8-week EEN therapy, and the mesenteric fat index (MFI), defined as the ratio of VFA to SFA, was calculated. The correlations between MFI and CD activity index and C-reactive protein level were also evaluated.

RESULTS

The median age of the patients in our study was 29 years, and the median duration of disease was 3.05 years. Both VFA (P = 0.029) and MFI (P = 0.021) were significantly decreased in patients after EEN, but no significant change was observed in SFA (P = 0.335). MFI was significantly correlated with CD activity index (r = 0.523, P = 0.001) and C-reactive protein (r = 0.634, P < 0.0001) in patients with active CD before EEN, although no positive correlations were observed in patients after EEN treatment.

CONCLUSIONS

EEN induction therapy was associated with a significant decrease in VFA in patients with CD, and MFI was significantly correlated with CD activity index and C-reactive protein in active CD. Thus, our data reveal additional beneficial therapeutic mechanisms of enteral nutrition treatment in CD.

Thigh fat and muscle each contribute to excess cardiometabolic risk in South Asians, independent of visceral adipose tissue

OBJECTIVE

To compare fat distribution and associations between fat depots and cardiometabolic traits in South Asians and Europeans.

METHODS

Five hundred and fourteen South Asians and 669 Europeans, aged 56-86. Questionnaires, record review, blood testing, and coronary artery calcification scores provided diabetes and clinical plus subclinical coronary heart disease (CHD) diagnoses. Abdominal visceral (VAT) and subcutaneous adipose tissue, thigh subcutaneous adipose tissue (TSAT), intermuscular and intramuscular thigh fat and thigh muscle were measured by CT.

RESULTS

Accounting for body size, South Asians had greater VAT and TSAT than Europeans, but less thigh muscle. Associations between depots and disease were stronger in South Asians than Europeans. In multivariable analyses in South Asians, VAT was positively associated with diabetes and CHD, while TSAT and thigh muscle were protective for diabetes, and thigh muscle for CHD. Differences in VAT and thigh muscle only partially explained the excess diabetes and CHD in South Asians versus Europeans. Insulin resistance did not account for the effects of TSAT or thigh muscle.

CONCLUSIONS

Greater VAT and TSAT and lesser thigh muscle in South Asians contributed to ethnic differences in cardiometabolic disease. Effects of TSAT and thigh muscle were independent of insulin resistance.

Relationship of anthropometric indices to abdominal and total body fat in youth: sex and race differences

OBJECTIVE

To determine the influence of sex and race on relationships between anthropometry (body mass index [BMI], waist circumference [WC], waist-to-height ratio [W/Ht]) and adiposity (fat mass [FM], abdominal subcutaneous [SAT] and visceral adipose tissue [VAT]) in African American and white youth.

METHODS

The sample included 382 youth 5-18 years of age. FM and abdominal adiposity were assessed using dual energy X-ray absorptiometry and magnetic resonance imaging. Regression was used to examine sex and race effects in the relationship between independent (BMI, WC, and W/Ht) and dependent (FM, SAT and VAT) variables.

RESULTS

BMI and WC were highly related to adiposity while W/Ht was moderately related. The association of BMI with FM and SAT was independent of sex and race, while the relationships of WC and W/Ht with FM and SAT were influenced by both sex and race. In contrast, the association between BMI and VAT was influenced by sex and race, while the relationships of WC and W/Ht with VAT were not.

CONCLUSIONS

WC and W/Ht have similar relationships with adiposity; however, WC presented stronger relationships. BMI is a predictor of overall adiposity but sex and race play a role in its relationship with VAT.

Obesity is associated with a lower resting oxygen saturation in the ambulatory elderly: results from the cardiovascular health study

BACKGROUND

The contribution of obesity to hypoxemia has not been reported in a community-based study. Our hypothesis was that increasing obesity would be independently associated with lower SpO2 in an ambulatory elderly population.

METHODS

The Cardiovascular Health Study ascertained resting SpO2 in 2,252 subjects over age 64. We used multiple linear regression to estimate the association of body mass index (BMI) with SpO2 and to adjust for potentially confounding factors. Covariates including age, sex, race, smoking, airway obstruction (based on spirometry), self reported diagnosis of emphysema, asthma, heart failure, and left ventricular function (by echocardiography) were evaluated.

RESULTS

Among 2,252 subjects the mean and median SpO2 were 97.6% and 98.0% respectively; 5% of subjects had SpO2 values below 95%. BMI was negatively correlated with SpO2 (Spearman R = -0.27, P < .001). The mean difference in SpO2 between the lowest and highest BMI categories (< 25 kg/m(2) and ≥ 35 kg/m(2)) was 1.33% (95% CI 0.89-1.78%). In multivariable linear regression analysis, SpO2 was significantly inversely associated with BMI (1.4% per 10 units of BMI, 95% CI 1.2-1.6, for whites/others, and 0.87% per 10 units of BMI, 95% CI 0.47-1.27, for African Americans).

CONCLUSIONS

We found a narrow distribution of SpO2 values in a community-based sample of ambulatory elderly. Obesity was a strong independent contributor to a low SpO2, with effects comparable to or greater than other factors clinically associated with lower SpO2.

Body mass index is positively associated with bone mineral density in US older adults

Literature has been conflicting as to whether obesity is protective against osteoporosis. Understanding the relationship is particularly important in light of the increasing prevalence of obesity among older adults. Study results confirm a protective association between obesity and osteoporosis in a recent, nationally representative sample of US older adults.

PURPOSE

Currently, the majority of US older adults are either overweight or obese. Evidence regarding the relationship between body composition measures and bone mass is conflicting, possibly because different measures of obesity reflect multiple mechanisms. Additionally, there are important age, gender, and racial differences in a risk of osteoporosis and fat mass composition. The objective of this study was to examine the association between body mass index (BMI) and bone mineral density (BMD) in a recent, nationally representative sample of US older adults as well as to see if this relationship differs by age, sex, and race.

METHODS

Data for this study were obtained from the National Health and Nutrition Examination Survey (2005-2008) for adults ages 50 and older (n = 3,296). Linear regression models were used to predict BMD of the femoral neck (measured by dual-energy X-ray absorptiometry (DXA)) as a function of BMI (measured height and weight) and a range of study covariates.

RESULTS

Every unit increase in BMI was associated with an increase of 0.0082 g/cm(2) in BMD (p < 0.001). Interaction terms for BMI and age (p = 0.345), BMI and sex (p = 0.413), and BMI and race (p = 0.725) were not statistically significant.

CONCLUSIONS

Study results confirm the positive association between BMI and BMD, and this relationship does not differ by age, sex, or race. A 10-unit increase in BMI (e.g., from normal BMI to obese) would result in moving an individual from an osteoporotic BMD level to a normal BMD level. Results demonstrate a protective, cross-sectional association between obesity and osteoporosis in a recent sample of US older adults.

Differential associations of abdominal visceral, subcutaneous adipose tissue with cardiometabolic risk factors between African and European Americans

OBJECTIVE

To examine the relative association of abdominal visceral adipose tissue (VAT) with cardiometabolic risk factors between African and European Americans.

METHODS

A cross-sectional study of 2,035 African Americans from the Jackson Heart Study (JHS) and 3,170 European Americans from the Framingham Heart Study (FHS) who underwent computed tomography assessment of VAT and subcutaneous adipose tissue (SAT) was conducted. The FHS participants were weighted to match the age distribution of the JHS participants, and the metabolic risk factors were examined by study groups in relation to VAT.

RESULTS

JHS participants had higher rates of obesity, hypertension, diabetes, and metabolic syndrome than FHS participants (all P = 0.001). The associations were weaker in JHS women for VAT with blood pressure, triglycerides, HDL-C, and total cholesterol (Pinteraction = 0.03-0.001) than FHS women. In contrast, JHS men had stronger associations for VAT with high triglycerides, low HDL, and metabolic syndrome (all Pinteraction = 0.001) compared to FHS men. Similar associations and gender patterns existed for SAT with most metabolic risk factors.

CONCLUSIONS

The relative association between VAT and cardiometabolic risk factors is weaker in JHS women compared to FHS women, whereas stronger associations with triglycerides and HDL were observed in JHS men.

Associations of body mass index with incident hypertension in American white, American black and Chinese Asian adults in early and middle adulthood: the Coronary Artery Risk Development in Young Adults (CARDIA) study, the Atherosclerosis Risk in Communities (ARIC) study and the People's Republic of China (PRC) study

The association of body mass index (BMI) with blood pressure may be stronger in Asian than non-Asian populations, however, longitudinal studies with direct comparisons between ethnicities are lacking. We compared the relationship of BMI with incident hypertension over approximately 9.5 years of follow-up in young (24-39 years) and middle-aged (45-64 years) Chinese Asians (n=5354), American Blacks (n=6076) and American Whites (n=13451). We estimated risk differences using logistic regression models and calculated adjusted incidences and incidence differences. To facilitate comparisons across ethnicities, standardized estimates were calculated using mean covariate values for age, sex, smoking, education and field center, and included the quadratic terms for BMI and age. Weighted least-squares regression models with were constructed to summarize ethnic-specific incidence differences across BMI. Wald statistics and p-values were calculated based on chi-square distributions. The association of BMI with the incidence difference for hypertension was steeper in Chinese (p<0.05) than in American populations during young and middle-adulthood. For example, at a BMI of 25 vs 21 kg/m2 the adjusted incidence differences per 1000 persons (95% CI) in young adults with a BMI of 25 vs those with a BMI of 21 was 83 (36- 130) for Chinese, 50 (26-74) for Blacks and 30 (12-48) for Whites; among middle-aged adults it was 137 (77-198) for Chinese, 49 (9-88) for Blacks and 54 (38-69) for Whites. Whether hypertension carries the same level of risk of stroke or cardiovascular disease across national or ethnic groups remains uncertain.

Gender and racial/ethnic differences in the associations of urinary phthalate metabolites with markers of diabetes risk: National Health and Nutrition Examination Survey 2001-2008

BACKGROUND

Phthalates are ubiquitous endocrine disrupting chemicals associated with diabetes. Although women and minorities are more likely to be exposed to phthalates, no prior studies have examined phthalate exposure and markers of diabetes risk evaluating effect modification by gender and race/ethnicity.

METHODS

We analyzed CDC data for 8 urinary phthalate metabolites from 3,083 non-diabetic, non-pregnant participants aged 12- < 80 years in the National Health and Nutrition Examination Survey (NHANES) 2001-2008. We used median regression to assess the associations between urinary phthalate metabolites and fasting blood glucose (FBG), fasting insulin and Homeostatic Model Assessment of insulin resistance (HOMA-IR), controlling for urinary creatinine as well as several sociodemographic and behavioral factors. Stratified analyses were conducted to compare the gender- and race/ethnicity-specific patterns for the associations.

RESULTS

Urinary levels of several phthalate metabolites, including MBzP, MnBP, MiBP, MCPP and ∑DEHP showed significant positive associations with FBG, fasting insulin and HOMA-IR. No clear difference was noted between men and women. Mexican-Americans and non-Hispanic blacks had stronger dose-response relationships for MnBP, MiBP, MCPP and ∑DEHP compared to non-Hispanic whites. For example, the highest quartile of MiBP relative to its lowest quartile showed a median FBG increase of 5.82 mg/dL (95% CI: 3.77, 7.87) in Mexican-Americans, 3.63 mg/dL (95% CI: 1.23, 6.03) in blacks and 1.79 mg/dL (95% CI: -0.29, 3.87) in whites.

CONCLUSIONS

The findings suggest that certain populations may be more vulnerable to phthalates with respect to disturbances in glucose homeostasis. Whether endocrine disrupting chemicals contribute to gender and racial/ethnic differences in diabetes risk will be an important area for further study.

Body mass index and mortality among blacks and whites adults in the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial

OBJECTIVE

In a large prospective cohort, we examined the relationship of body mass index (BMI) with mortality among blacks and compared the results to those among whites in this population.

DESIGN AND METHODS

The study population consisted of 7,446 non-Hispanic black and 130,598 white participants, ages 49-78 at enrollment, in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. BMI at baseline, BMI at age 20, and BMI change were calculated using self-reported and recalled height and weight. Relative risks were stratified by race and sex and adjusted for age, education, marital status, and smoking.

RESULTS

During follow-up, 1,495 black and 18,236 white participants died (mean = 13 years). Clear J-shaped associations between BMI and mortality were observed among white men and women. Among black men and women, the bottoms of these curves were flatter, and increasing risks of death with greater BMI were observed only at higher BMI levels (≥35.0). Associations for BMI at age 20 and BMI change also appeared to be stronger in magnitude in whites versus blacks, and these racial differences appeared to be more pronounced among women.

CONCLUSION

Our results suggest that BMI may be more weakly associated with mortality in blacks, particularly black women, than in whites.

Guidelines updates in the treatment of obesity or metabolic syndrome and hypertension

Obesity and overweight are nowadays very prevalent worldwide. They are known to be linked with an increased risk of developing cardiovascular comorbidities and mortality. Abdominal obesity is frequently associated with a collection of metabolic disorders that include elevated blood pressure, characteristic lipid abnormalities (low high-density lipoprotein cholesterol and high triglycerides) and increased fasting glucose, with an underlying situation of insulin resistance, which has been defined as metabolic syndrome, conferring a high cardiovascular risk profile to these subjects. A multidisciplinary approach is required, including lifestyle changes and pharmacological and surgical approaches. Intensive management of all the risk factors of the metabolic syndrome is also needed to reduce body weight and waist circumference, lessen insulin resistance and avoid the development of new-onset diabetes and cardiovascular disease associated with this entity. This article will review the recently published literature and guideline updates on this topic, although it is not yet included in the highlights.

Anthropometric predictors of visceral adiposity in normal-weight and obese adolescents

BACKGROUND

Obesity and fat distribution patterns [subcutaneous vs. visceral adipose tissue (VAT)] are important predictors of future cardiometabolic risk. As accurate VAT measurement entails imaging, surrogate anthropometric measurements that would be cheaper and quicker to obtain would be highly desirable. Sagittal abdominal diameter (SAD) may be better than other VAT surrogate measures in adults, but the value of SAD to predict magnetic resonance imaging (MRI)-determined VAT in adolescents of different races, sexes, and pubertal stages has not been determined.

AIM

To test the hypothesis that SAD correlates more strongly with volumetric VAT than other anthropometric measurements, independent of age, sex, race, and Tanner stage.

SUBJECTS AND METHODS

Twenty-eight normal-weight and 44 obese adolescents underwent Tanner staging, anthropometric examinations, and abdominal MRI for volumetric partitioned fat calculation.

RESULTS

VAT increased exponentially in the body mass index (BMI) > 97th percentile range. SAD, waist circumference (WC), BMI, and BMI Z-score correlated strongly with VAT (correlation coefficients of 0.85-0.86, all p-values < 0.0005); waist-hip ratio was less predictive of VAT (r = 0.68, p < 0.0005). On hierarchical regression, the strongest predictors of VAT in obese subjects were BMI Z-score and SAD (R(2)  = 0.34 vs. 0.31, respectively, p < 0.0005); in normal-weight subjects, most anthropometric measures predicted VAT equally (R(2)  = 0.16-0.18, p-values = 0.018-0.026).

CONCLUSIONS

Unlike adults, in obese adolescents, SAD is not the strongest predictor of visceral adiposity. BMI Z-score is equivalently predictive and, together with BMI, provides sufficient information to assess visceral adiposity; more specialized anthropometric measurements (e.g., SAD and WC) do not add additional predictive value.

Body size, modifying factors, and postmenopausal breast cancer risk in a multiethnic population: the San Francisco Bay Area Breast Cancer Study

Data on body size and postmenopausal breast cancer in Hispanic and African American women are inconsistent, possibly due to the influence of modifying factors. We examined associations between adiposity and risk of breast cancer defined by hormone receptor status in a population-based case-control study conducted from 1995-2004 in the San Francisco Bay Area. Multivariate adjusted odds ratios and 95% confidence intervals were calculated using unconditional logistic regression. Associations with body size were limited to women not currently using menopausal hormone therapy (801 cases, 1336 controls). High young-adult body mass index (BMI) was inversely associated with postmenopausal breast cancer risk, regardless of hormone receptor status, whereas high current BMI and high adult weight gain were associated with two-fold increased risk of estrogen receptor and progesterone receptor positive breast cancer, but only in women with a low young-adult BMI (≤22.4 kg/m(2)) or those with ≥15 years since menopause. Odds ratios were stronger among non-Hispanic Whites than Hispanics and African Americans. Waist circumference and waist-to-height ratio increased breast cancer risk in Hispanics and African Americans only, independent of BMI. These findings emphasize the importance of considering tumor hormone receptor status and other modifying factors in studies of racially/ethnically diverse populations.

Differences in body composition between metabolically healthy obese and metabolically abnormal obese adults

Potential differences in body composition between metabolically healthy obese (MHO) and metabolically abnormal obese (OA) adults were explored with 395 obese adults from the Pennington Center Longitudinal Study (18-68 years). Adults were classified as OA (≥2 risk factors: blood pressure ≥130/85 mmHg; triglycerides ≥150 mg dl(-1); high-density lipoprotein cholesterol: men <40, women <50 mg dl(-1); fasting glucose ≥100 mg dl(-1); waist circumference: ≥102 cm men, women ≥88 cm) or MHO (<2 risk factors). Whole-body bone mineral density and content, percent body fat, fat mass, lean mass and trunk adipose tissue mass were measured with dual-energy X-ray absorptiometry. Visceral (VAT), subcutaneous (SAT) and total abdominal adipose tissue (TAT) were measured with computed tomography. Gender-specific general linear regression models were used to determine differences in body composition between MHO and OA controlling for age, race, smoking status and menopause status. In men, MHO had lower fat mass (kg and %), trunk adipose tissue, VAT, SAT, TAT and lean mass compared with OA. MHO women had lower fat mass (kg), lean mass, trunk adipose tissue, VAT and TAT when compared with OA women. In conclusion, OA and MHO cardiometabolic profiles are characterized by differences in body composition consistent between genders.

The importance of waist circumference and BMI for mortality risk in diabetic adults

OBJECTIVE

We aimed to determine the associations of waist circumference (WC) and BMI with all-cause mortality among patients with diabetes.

RESEARCH DESIGN AND METHODS

The sample included 847 white and 553 African American patients (18-69 years of age) with diabetes. Height, weight, and WC were measured, and the BMI (kg/m2) was calculated. Cox regression was used to analyze the associations of BMI and WC with mortality, adjusting for age, sex, race, examination year, smoking status, alcohol consumption, and physical activity. Hazard ratios (HRs) are expressed per standard deviation of each independent variable.

RESULTS

A total of 86 deaths occurred during 6.7 years of follow-up. After adjustment for covariates, WC (HR 1.40 [95% CI 1.14-1.72]) and BMI (1.29 [1.04-1.61]) demonstrated significant relationships with mortality.

CONCLUSIONS

The results indicate that maintaining a healthy WC and BMI are both important for individuals living with diabetes.

Associations between depression and different measures of obesity (BMI, WC, WHtR, WHR)

BACKGROUND

Growing evidence suggests that abdominal obesity is a more important risk factor for the prognosis of cardiovascular and metabolic diseases than BMI. Somatic-affective symptoms of depression have also been linked to cardiovascular risk. The relationship between obesity and depression, however, has remained contradictory. Our aim was therefore to relate body mass index (BMI) and different measures for abdominal obesity (waist circumference, WC, waist-to-hip ratio, WHR, waist-to-height ratio, WHtR) to somatic vs. cognitive-affective symptoms of depression.

METHODS

In a cross-sectional population based study, data on the first N = 5000 participants enrolled in the Gutenberg Health Study (GHS) are reported. To analyze the relationship between depression and obesity, we computed linear regression models with the anthropometric measure (BMI, WC, WHR, WHtR) as the dependent variable and life style factors, cardiovascular risk factors and psychotropic medications as potential confounders of obesity/depression.

RESULTS

We found that only the somatic, but not the cognitive-affective symptoms of depression are consistently positively associated with anthropometric measures of obesity.

CONCLUSIONS

We could demonstrate that the somatic-affective symptoms of depression rather than the cognitive-affective symptoms are strongly related to anthropometric measures. This is also true for younger obese starting at the age of 35 years. Our results are in line with previous studies indicating that visceral adipose tissue plays a key role in the relationship between obesity, depression and cardiovascular disease.

Associations of visceral and abdominal subcutaneous adipose tissue with markers of cardiac and metabolic risk in obese adults

OBJECTIVE

Visceral (VAT) and abdominal subcutaneous (SAT) adipose tissues contribute to obesity but may have different metabolic and atherosclerosis risk profiles. We sought to determine the associations of abdominal VAT and SAT mass with markers of cardiac and metabolic risk in a large, multiethnic, population-based cohort of obese adults.

DESIGN AND METHODS

Among obese participants in the Dallas Heart Study, we examined the cross-sectional associations of abdominal VAT and SAT mass, assessed by magnetic resonance imaging (MRI) and indexed to body surface area (BSA), with circulating biomarkers of insulin resistance, dyslipidemia, and inflammation (n = 942); and with aortic plaque and liver fat by MRI and coronary calcium by computed tomography (n = 1200). Associations of VAT/BSA and SAT/BSA were examined after adjustment for age, sex, race, menopause, and body mass index.

RESULTS

In multivariable models, VAT significantly associated with the homeostasis model assessment of insulin resistance (HOMA-IR), lower adiponectin, smaller LDL and HDL particle size, larger VLDL size, and increased LDL and VLDL particle number (p < 0.001 for each). VAT also associated with prevalent diabetes, metabolic syndrome, hepatic steatosis, and aortic plaque (p < 0.001 for each). VAT independently associated with C-reactive protein but not with any other inflammatory biomarkers tested. In contrast, SAT associated with leptin and inflammatory biomarkers, but not with dyslipidemia or atherosclerosis. Associations between SAT and HOMA-IR were significant in univariable analyses but attenuated after multivariable adjustment.

CONCLUSION

VAT associated with an adverse metabolic, dyslipidemic, and atherogenic obesity phenotype. In contrast, SAT demonstrated a more benign phenotype, characterized by modest associations with inflammatory biomarkers and leptin, but no independent association with dyslipidemia, insulin resistance, or atherosclerosis in obese individuals. These findings suggest that abdominal fat distribution defines distinct obesity sub-phenotypes with heterogeneous metabolic and atherosclerosis risk.

Different associations of subscapular and triceps skinfold thicknesses with pathogen load: an ecogeographical analysis

OBJECTIVES

The dominant evolutionary perspective on adipose tissue has considered it a relatively inert energy store. However, variability in adipose tissue distribution has recently been associated with age, parity, thermal environment and immune function. Genes regulating the innate immune system are more strongly expressed in deep-lying than peripheral adipose tissue. We hypothesized that central adiposity would correlate more strongly than peripheral adiposity with pathogen load across populations.

METHODS

Primary outcomes were subscapular and triceps skinfolds from 133 male and 106 female populations. National values for disability-adjusted life years lost, attributable to infectious diseases, were used to index pathogen load. Linear mixed-effects models were fitted, including a random effect term by country to investigate the association of each skinfold with pathogen load, adjusting for the other skinfold, mean annual temperature and clustering of the populations across countries.

RESULTS

Adjusting for subscapular skinfold, triceps skinfold was not associated with pathogen load in either sex. Adjusting for triceps skinfold, subscapular skinfold was negatively associated with pathogen load in both sexes (P < 0.02). These associations were independent of variability in annual temperature. Adjusting for pathogen load and temperature, Oceanic populations had a different fat distribution compared to other populations.

CONCLUSIONS

Across populations, higher pathogen load was associated with reduced central but not peripheral skinfolds, supporting the hypothesis that central adiposity is more closely associated with immune function. This scenario might explain why some populations increase disproportionately in central adiposity when the environment shifts from low-energy high-pathogen status to high-energy low-pathogen status.

Prevalence of polycystic ovary syndrome in adolescents

OBJECTIVE

To investigate the prevalence of polycystic ovary syndrome (PCOS) in adolescents and its association with obesity.

DESIGN

Cross-sectional study using electronic medical records.

SETTING

Not applicable.

PATIENT(S)

Adolescents aged 15-19 years (n = 137,502).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

PCOS diagnosed or defined according to National Institutes of Health (NIH) criteria.

RESULT(S)

The prevalence of a confirmed diagnosis of PCOS was 0.56%, which increased to 1.14% when undiagnosed cases with documented symptoms qualifying for PCOS according to NIH criteria were included. Compared with normal/underweight girls, the odds ratios (OR and 95% confidence interval [CI]) for confirmed PCOS diagnosis were 3.85 (3.04-4.88), 10.25 (8.16-12.84), and 23.10 (18.66-28.61) for overweight, moderately obese, and extremely obese adolescents, respectively, after adjusting for potential confounders. When adolescents with two or more supportive diagnoses were included (diagnosed and undiagnosed PCOS-NIH), the ORs (95% CI) for PCOS-NIH by weight class were significantly attenuated to 2.95 (2.53-3.44), 6.73 (5.78-7.83), and 14.65 (12.73-16.86) for overweight, moderately obese, and extremely obese adolescents, respectively.

CONCLUSION(S)

Overweight and obesity were associated with higher odds of PCOS in adolescents. Studies based solely on diagnosis codes may underestimate the prevalence of PCOS and overestimate the magnitude of the association between obesity and PCOS.

The relationship between visceral obesity and colorectal cancer

SUMMARY The prevalence of obesity continues to rise globally and physicians and healthcare systems have to prepare for rising rates of obesity-associated disease. Aside from cardiovascular disease and diabetes, recent evidence suggests a strong association between obesity and the development of cancer, including colorectal cancer. Using BMI as a marker for obesity, excess body fat is associated with an increased risk of colorectal cancer; however, this relationship appears to be stronger among males and more consistent for colon rather than rectal cancer. Epidemiologic literature evaluating the risk of obesity on colorectal cancer survival using BMI is less consistent. Recent evidence suggests that visceral fat plays a greater role in the development of disease. Current research on the effect of visceral obesity on colorectal cancer outcomes is in its infancy, but may drive a new wave of practice for this ever-growing population of colorectal cancer patients.

Ethnic and sex differences in visceral, subcutaneous, and total body fat in children and adolescents

OBJECTIVE

This study investigated ethnic and sex differences in the distribution of fat during childhood and adolescence.

DESIGN AND METHODS

A cross-sectional sample (n = 382), aged 5-18 years, included African American males (n = 84), White males (n = 96), African American females (n = 118), and White females (n = 84). Measures for total body fat (TBF) mass and abdominal adipose tissue (total volume and L4-L5 cross-sectional area) for both subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) depots were assessed by dual-energy X-ray absorptiometry and magnetic resonance image, respectively. Analyses of covariance (ANCOVAs) were used to determine ethnic and sex differences in TBF (adjusted for age) and ethnic and sex differences in SAT and VAT (adjusted for both age and TBF).

RESULTS

Age-adjusted TBF was greater in African Americans (P = 0.017) and females (P < 0.0001) compared with Whites and males, respectively. In age- and TBF-adjusted ANCOVAs, no differences were found in the SAT. The VAT volume was, however, greater in Whites (P < 0.0001) and males (P < 0.0001) compared with African Americans and females, respectively. Similar patterns were observed in SAT and VAT area at L4-L5.

CONCLUSIONS

The demonstrated ethnic and sex differences are important confounders in the prevalence of obesity and in the assignment of disease risk in children and adolescents.

Anthropometric markers of obesity and mortality in white and African American adults: the pennington center longitudinal study

OBJECTIVE

The purpose of this study was to determine the association between anthropometric measures of obesity and all-cause mortality in white and African American men and women.

DESIGN AND METHODS

The sample included 14,343 adults 18-89 years of age. Height, weight, and waist and hip circumferences were measured, and the BMI (kg m(-2) ), body adiposity index (BAI = ([hip circumference in centimeters]/[height in meters])(1.5) - 18), waist-to-height ratio (WHtR) and waist-to-hip ratio (WHR) were computed. Vital status of the participants was determined from linkage with the National Death Index through 2009. Cox regression was used to assess the association between anthropometry and all-cause mortality, adjusting for age, sex, year of baseline examination, study code, smoking status, alcohol consumption and physical activity. Hazard ratios (HR) are expressed per standard deviation of each variable.

RESULTS

A total of 438 deaths occurred during 120,637 person-years of follow-up. All anthropometric markers demonstrated significant associations with all-cause mortality in white subjects. In multivariable-adjusted models, BMI (HR 1.34; 95% CI: 1.19-1.50), waist circumference (1.41; 1.25-1.60), BAI (1.34; 1.17-1.53), WHtR (1.46; 1.28-1.65), and WHR (1.40; 1.23-1.61) all demonstrated significant relationships with mortality in white participants, but not in African Americans. In categorical analyses, there was a significant association between BMI status and mortality in whites but not African Americans. However, the risk associated with elevated waist circumference was similar in whites (1.49; 1.15-1.94) and African Americans (1.60; 1.06-2.40).

CONCLUSION

In summary, this study has demonstrated race differences in the association between anthropometry and all-cause mortality.

Clinical utility of visceral adipose tissue for the identification of cardiometabolic risk in white and African American adults

BACKGROUND

Visceral adipose tissue (VAT) has been identified as a harmful fat depot, and sex and race differences in VAT have been reported in white and African Americans.

OBJECTIVES

We determined the clinical utility of VAT in the identification of individuals at elevated cardiometabolic risk in white and African American adults and compared the clinical utility with measures obtained by using dual-energy X-ray absorptiometry (DXA) and anthropometric measures.

DESIGN

The sample included 429 white women, 311 African American women, 406 white men, and 100 African American men who were 18-74 y of age. VAT was measured by using computed tomography, fat mass (FM) and percentage of body fat were measured by using DXA, and waist circumference (WC) and BMI were assessed. Receiver operating characteristic curves were used to compare the utility of measures in the identification of participants in the upper quintile of a continuous score derived from principal components analysis of fasting glucose, HDL cholesterol, triglycerides, and blood pressure.

RESULTS

The clinical utility of measures varied across sex-by-race groups. In the overall sample, the areas under the curve were significantly higher for VAT and WC in comparison with the other indicators. Identified VAT thresholds were higher in white men (140 cm(2)) and women (141 cm(2)) than in African American men (82 cm(2)) and women (97 cm(2)).

CONCLUSIONS

VAT and WC showed greater clinical utility than did other obesity measures. Because of the complexity of measuring VAT, the use of WC is recommended for the identification of adults with elevated cardiometabolic risk factors. The Pennington Center Longitudinal Study was registered at clinicaltrials.gov as NCT00959270.

Pathophysiology of human visceral obesity: an update

Excess intra-abdominal adipose tissue accumulation, often termed visceral obesity, is part of a phenotype including dysfunctional subcutaneous adipose tissue expansion and ectopic triglyceride storage closely related to clustering cardiometabolic risk factors. Hypertriglyceridemia; increased free fatty acid availability; adipose tissue release of proinflammatory cytokines; liver insulin resistance and inflammation; increased liver VLDL synthesis and secretion; reduced clearance of triglyceride-rich lipoproteins; presence of small, dense LDL particles; and reduced HDL cholesterol levels are among the many metabolic alterations closely related to this condition. Age, gender, genetics, and ethnicity are broad etiological factors contributing to variation in visceral adipose tissue accumulation. Specific mechanisms responsible for proportionally increased visceral fat storage when facing positive energy balance and weight gain may involve sex hormones, local cortisol production in abdominal adipose tissues, endocannabinoids, growth hormone, and dietary fructose. Physiological characteristics of abdominal adipose tissues such as adipocyte size and number, lipolytic responsiveness, lipid storage capacity, and inflammatory cytokine production are significant correlates and even possible determinants of the increased cardiometabolic risk associated with visceral obesity. Thiazolidinediones, estrogen replacement in postmenopausal women, and testosterone replacement in androgen-deficient men have been shown to favorably modulate body fat distribution and cardiometabolic risk to various degrees. However, some of these therapies must now be considered in the context of their serious side effects. Lifestyle interventions leading to weight loss generally induce preferential mobilization of visceral fat. In clinical practice, measuring waist circumference in addition to the body mass index could be helpful for the identification and management of a subgroup of overweight or obese patients at high cardiometabolic risk.

Gender differences in the association of visceral and subcutaneous adiposity with adiponectin in African Americans: the Jackson Heart Study

BACKGROUND

Adiponectin, paradoxically reduced in obesity and with lower levels in African Americans (AA), modulates several cardiometabolic risk factors. Because abdominal visceral adipose tissue (VAT), known to be reduced in AA, and subcutaneous adipose tissue (SAT) compartments may confer differential metabolic risk profiles, we investigated the associations of VAT and SAT with serum adiponectin, separately by gender, with the hypothesis that VAT is more strongly inversely associated with adiponectin than SAT.

METHODS

Participants from the Jackson Heart Study, an ongoing cohort of AA (n = 2,799; 64% women; mean age, 55 ± 11 years) underwent computer tomography assessment of SAT and VAT volumes, and had stored serum specimens analyzed for adiponectin levels. These levels were examined by gender in relation to increments of VAT and SAT.

RESULTS

Compared to women, men had significantly lower mean levels of adiponectin (3.9 ± 3.0 μg/mL vs. 6.0 ± 4.4 μg/mL; p < 0.01) and mean volume of SAT (1,721 ± 803 cm(3) vs. 2,668 ± 968 cm(3); p < 0.01) but significantly higher mean volume of VAT (884 ± 416 cm(3) vs. 801 ± 363 cm(3); p < 0.01). Among women, a one standard deviation increment in VAT was inversely associated with adiponectin (β = - 0.13; p < 0.0001) after controlling for age, systolic blood pressure, fasting plasma glucose, high-density lipoprotein cholesterol, triglycerides, education, pack-years of smoking and daily intake of alcohol. The statistically significant inverse association of VAT and adiponectin persisted after additionally adjusting for SAT, body mass index (BMI) and waist circumference (WC), suggesting that VAT provides significant information above and beyond BMI and WC. Among men, after the same multivariable adjustment, there was a direct association of SAT and adiponectin (β = 0.18; p = 0.002) that persisted when controlling for BMI and WC, supporting a beneficial effect of SAT. Insulin resistance mediated the association of SAT with adiponectin in women.

CONCLUSION

In African Americans, abdominal visceral adipose tissue had an inverse association with serum adiponectin concentrations only among women. Abdominal subcutaneous adipose tissue appeared as a protective fat depot in men.

Association of regional body composition with bone mineral density in HIV-infected and HIV-uninfected women: women's interagency HIV study

OBJECTIVE

To understand how regional body composition affects bone mineral density (BMD) in HIV-infected and HIV-uninfected women.

METHODS

Dual energy x-ray absorptiometry was used to measure regional lean and fat mass and BMD at lumbar spine (LS), total hip (TH), and femoral neck (FN) in 318 HIV-infected and 122 HIV-uninfected Women's Interagency HIV Study participants at baseline and 2 and 5 years later. Total lean and fat mass were measured using bioimpedance analysis. Multivariate marginal linear regression models assessed the association of HIV status and body composition on BMD change.

RESULTS

Compared with HIV-uninfected women, HIV-infected women were older (44 vs. 37 years), more likely to be Hepatitis C virus-infected (32% vs. 14%), and postmenopausal (26% vs. 3%) and had lower baseline total fat mass, trunk fat, and leg fat. In multivariate models, increased total lean mass was independently associated with increased BMD at LS, TH, and FN, and total fat mass was associated with increased BMD at TH and FN (all P < 0.05). When total fat was replaced in multivariate models with trunk fat and leg fat, increased trunk fat (and not leg fat) was associated with increased TH and FN BMD (P < 0.001).

CONCLUSIONS

Total fat and lean mass are strong independent predictors of TH and FN BMD, and lean mass was associated with greater LS BMD. Regardless of HIV status, greater trunk fat (and not leg fat) was associated with increased TH and FN BMD, suggesting that weight-bearing fat may be a more important predictor of BMD in the hip.

Visceral obesity and colorectal cancer: are we missing the boat with BMI?

INTRODUCTION

Compared to subcutaneous fat, visceral fat is more metabolically active, leading to chronic inflammation and tumorigenesis. The aim of this study is to describe the effect of visceral obesity on colorectal cancer outcomes using computed tomography (CT) imaging to measure visceral fat.

MATERIALS AND METHODS

We conducted a retrospective chart review of patients who underwent surgical resection for colorectal cancer. Visceral fat volume was measured by preoperative CT scans. Final analysis was performed by stratifying patients based on oncologic stage.

RESULTS

Two hundred nineteen patients met the inclusion criteria, 111 viscerally obese and 108 nonobese. Body mass index (BMI) weakly correlated with visceral fat volume measurements (R (2) = 0.304). Whereas obese patients had no difference in survival when categorizing obesity by BMI, categorizing based on visceral fat volume resulted in significant differences in stage II and stage III patients. In stage II cancer, viscerally obese patients had a nearly threefold decrease in disease-free survival (hazard ratio (HR) = 2.72; 95 % confidence interval (CI) = 1.21, 6.10). In stage III cancer, viscerally obese patients had a longer time to recurrence (HR = 0.39; 95 % CI = 0.16, 0.99).

CONCLUSION

This study shows that viscerally obese patients with stage II colorectal cancer are at higher risk for poor outcomes and should be increasingly considered for adjuvant chemotherapy.

The double burden of malnutrition and cardiometabolic risk widens the gender and socio-economic health gap: a study among adults in Burkina Faso (West Africa)

OBJECTIVE

To document the double burden of malnutrition and cardiometabolic risk factors (CMRF) in adults and its occurrence according to different sociodemographic parameters.

DESIGN

Population-based cross-sectional observational study. We first randomly selected 330 households stratified by tertile of the income levels proxy as low, middle and high income.

SETTING

Northern district of Ouagadougou, the capital city of Burkina Faso.

SUBJECTS

In each income stratum, 110 individuals aged 25-60 years and who had lived permanently in Ouagadougou for at least 6 months were randomly selected, followed with collection of anthropometric, socio-economic and clinical data, and blood samples.

RESULTS

The overall obesity/overweight prevalence was 24.2 % and it was twice as high in women as in men (34.1 % v. 15.5 %, P < 0.001). Hypertension, hyperglycaemia and low HDL cholesterol prevalence was 21.9 %, 22.3 % and 30.0 %, respectively, without gender difference. The prevalence of the metabolic syndrome was 10.3 %. Iron depletion and vitamin A deficiency affected 15.7 % and 25.7 % of participants, respectively, with higher rates in women. Coexistence of at least one nutritional deficiency and one CMRF was observed in 23.5 % of participants, and this 'double burden' was significantly higher in women than in men (30.4 % v. 16.1 %, P = 0.008) and in the low income group.

CONCLUSIONS

CMRF are becoming a leading nutritional problem in adults of Ouagadougou, while nutritional deficiencies persist. The double nutritional burden exacerbates health inequities and calls for action addressing both malnutrition and nutrition-related chronic diseases.

Mapping body fat distribution: a key step towards the identification of the vulnerable patient?

Although excess body fat is a significant health hazard, estimation of body fat content with the body mass index may not adequately reflect the amount of atherogenic adipose tissue (AT), i.e. visceral and ectopic fat. As opposed to subcutaneous AT that supposedly acts as a metabolic sink buffering excess dietary energy, visceral or intra-abdominal AT depots respond to several external stimuli that trigger lipolysis and secretion of free fatty acids (FFAs). Reaching the liver, FFAs accumulate in the liver and, over time, promote a chronic condition known as non-alcoholic fatty liver disease (NAFLD). The liver of the typical NAFLD patient secretes large amounts of very-low-density lipoproteins, the lipid content of which may accumulate in additional organs (skeletal muscle, heart, and pancreas). Here, we review the evidence emerging from functional and population studies that point towards an important role of ectopic fat accumulation in the pathophysiology of type 2 diabetes and cardiovascular disease. We conclude that although patients with impaired glycemic control or type 2 diabetes are at increased cardiovascular disease (CVD) risk, estimating cardiovascular risk goes wellbeyond the assessment of glycemic control and traditional CVD risk factors, and the estimation of visceral/ectopic fat deposition via readily available imaging techniquesshould be considered.

Measures of general and central obesity and risk of type 2 diabetes in a Ghanaian population

OBJECTIVE

The epidemic of obesity and type 2 diabetes is evident in sub-Saharan Africa (SSA). However, their associations have hardly been examined in this region.

METHODS

A hospital-based case-control study in urban Ghana consisting of 1221 adults (542 cases and 679 controls) investigated the role of anthropometric parameters for diabetes. Logistic regression was used for analysis. The discriminative power and population-specific cut-off points for diabetes were identified by receiver operating characteristic curves.

RESULTS

The strongest association with diabetes was observed for waist-to-hip ratio: age-adjusted odds ratios per 1 standard deviation difference were 1.95 (95% confidence interval [CI]: 1.64-2.31) in women and 1.40 [1.01-1.94] in men. Also, among women, the odds of diabetes increased with higher waist circumference (1.35 [1.17-1.57]) and waist-to-height ratio (1.29 [1.12-1.50]). Among men, this was not discernible. Rather, hip circumference was inversely related (0.69 [0.50-0.95]). Body mass index was neither associated with diabetes in women (1.01 [0.88-1.15]) nor in men (0.74 [0.52-1.04]). Among both genders, waist-to-hip ratio showed the best discriminative ability for diabetes in this population and the optimal cut-off points were ≥ 0.88 in women and ≥ 0.90 in men. Recommended cut-off points for body mass index and waist circumference had a poor predictive ability.

CONCLUSION

Our findings suggest that measures of central rather than general obesity relate to type 2 diabetes in SSA. It remains to be verified from larger population-based epidemiological studies whether anthropometric targets of obesity prevention in SSA differ from those in developed countries.

Adiposity, fat patterning, and the metabolic syndrome among diverse youth: the EPOCH study

OBJECTIVES

To assess fat distribution, prevalence of obesity, and the metabolic syndrome among diverse 6-13-year-old Colorado youth to better understand racial/ethnic influences on adiposity and metabolic syndrome.

STUDY DESIGN

We measured body mass index, subscapular-to-triceps skinfold ratio, waist circumference, dietary fat, and physical activity in 422 youth (47% non-Hispanic White, 44% Hispanic, and 9% African-American). Visceral adipose tissue, subcutaneous adipose tissue, and intramyocellular lipid were measured with magnetic resonance techniques. Multiple-linear regression was used to assess associations between race/ethnicity and adiposity patterns.

RESULTS

Hispanic and African-American youth had a higher prevalence of obesity and metabolic syndrome compared with non-Hispanic White youth. Both groups displayed a more centralized fat distribution and larger volumes of subcutaneous tissue, compared with non-Hispanic White youth. After controlling for body mass index, these differences were attenuated, and for a given body size, African-American youth showed significantly lower visceral adipose tissue than non-Hispanic White youth. However, both Hispanic and African-American youth showed higher intermyocellular lipid in skeletal muscle compared with non-Hispanic Whites, independent of body size.

CONCLUSIONS

Racial/ethnic minorities experience higher overall adiposity, and may also have an increased risk for early development of metabolic syndrome relative to non-Hispanic White youth, beyond their increased obesity risk.

Body mass index and renal cell cancer: the influence of race and sex

BACKGROUND

Obesity is a risk factor for renal cell (or renal) cancer. The increasing prevalence of obesity may be contributing to the rising incidence of this cancer over the past several decades. The effects of early-age obesity and change in body mass index (BMI) on renal cancer have been studied less thoroughly, and the influence of race has never been formally investigated.

METHODS

Using data gathered as part of a large case-control study of renal cancer (1214 cases and 1234 controls), we investigated associations with BMI at several time points, as well as with height. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed using logistic regression modeling. Race- and sex-stratified analyses were conducted to evaluate subgroup differences.

RESULTS

Obesity (BMI ≥ 30 kg/m) early in adulthood (OR = 1.6 [95% CI = 1.1 to 2.4]) and 5 years before diagnosis (1.6 [1.1 to 2.2]) was associated with renal cancer. The association with early-adult obesity was stronger among whites than blacks (test for interaction, P = 0.006), whereas the association with obesity near diagnosis was marginally stronger in women than men (test for interaction, P = 0.08). The strongest association with renal cancer was observed for obese whites both in early adulthood and before interview (2.6 [1.5 to 4.4]); this association was not present among blacks. Estimates of the annual excess rate of renal cancer (per 100,000 persons) attributed to both overweight and obesity (BMI > 25 kg/m) ranged from 9.9 among black men to 5.6 among white women.

CONCLUSION

Obesity, both early and later in life, is associated with an increased risk of renal cancer. The association with early obesity seems to be stronger among whites than blacks.

Adipose tissue heterogeneity: implication of depot differences in adipose tissue for obesity complications

Obesity, defined as excess fat mass, increases risks for multiple metabolic diseases, such as type 2 diabetes, cardiovascular disease and several types of cancer. Over and above fat mass per se, the pattern of fat distribution, android or truncal as compared to gynoid or peripheral, has a profound influence on systemic metabolism and hence risk for metabolic diseases. Increases in upper body adipose tissue (visceral and abdominal subcutaneous) confer an independent risk, while the quantity of gluteofemoral adipose tissue is protective. Variations in the capacity of different depots to store and release fatty acids and to produce adipokines are important determinants of fat distribution and its metabolic consequences. Depot differences in cellular composition and physiology, including innervation and blood flow, likely influence their phenotypic properties. A number of lines of evidence also support the idea that adipocytes from different anatomical depots are intrinsically different as a result of genetic or developmental events. In this chapter, we will review the phenotypic characteristics of different adipose depots and mechanisms that link their depot-specific biology to metabolic complications in men and women.