Obesity in African-Americans: The role of physiology

Sex differences in Alzheimer's disease blood biomarkers in a Caribbean population of African ancestry: The Tobago Health Study

INTRODUCTION

Alzheimer's disease (AD) is increasing in the Caribbean, especially for persons of African ancestry (PAA) and women. However, studies have mostly utilized surveys without AD biomarkers.

METHODS

In the Tobago Health Study (n = 309; 109 women, mean age 70.3 ± 6.6), we assessed sex differences and risk factors for serum levels of phosphorylated tau-181 (p-tau181), amyloid-beta (Aβ)42/40 ratio, glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL). Blood samples were from 2010 to 2013 for men and from 2019 to 2023 for women.

RESULTS

Women were more obese, hypertensive, and sedentary but reported less smoking and alcohol use than men (age-adjusted p < 0.04). Compared to men, women had worse levels of AD biomarkers, with higher p-tau181 and lower Aβ42/40, independent of covariates (p < 0.001). In sex-stratified analyses, higher p-tau181 was associated with older age in women and with hypertension in men. GFAP and NfL did not differ by sex.

DISCUSSION

Women had worse AD biomarkers than men, unexplained by age, cardiometabolic diseases, or lifestyle. Studying risk factors for AD in PAA is warranted, especially for women earlier in life.

Tailoring African American Faith Community-Based Diabetes Self-Management Education

ABSTRACT

African Americans (AA) experience a disparate effect of type II diabetes (T2D). For this nurse-led pilot study, a pre-validated 6-week diabetes self-management education (DSME) program was implemented in a faith community setting and tailored to the participants' faith and culture by using short scriptural lessons, prayers, and individual sharing. Participants demonstrated improvements in fasting blood glucose (p = .042), diabetes knowledge (p = .002), and psychosocial self-efficacy (p = .001). Although generalizability of findings is limited, the structure and methods used in tailoring this DSME program could be transferable to other faith-based settings.

A review of dairy food intake for improving health among black geriatrics in the US

The transition to older adulthood is generally marked by progressive declines in body composition, metabolism, cognitive function, and immunity. For socially disadvantaged geriatric populations such as Black Americans, this life stage may also include additional stressors, including dealing with discrimination, poor access to healthcare, and food insecurity. These types of chronic stressors are linked to a higher allostatic load, which is associated with accelerated biological aging, higher rates of adverse health outcomes, and an overall lower quality of life. Of the numerous factors involved in healthy aging, a growing body of research indicates that consuming a higher quality diet that is rich in fruits, vegetables, whole grains, protein foods, and dairy foods, is one of the most potent factors for helping to protect against age-related disease progression. Among the food groups listed above that are recommended by the 2020-2025 Dietary Guidelines for Americans dairy foods are unique in their ability to provide several of the essential nutrients (e.g., high-quality protein, calcium, potassium, vitamin B12, and vitamin D in fortified products) that are most often inadequately consumed by older Black Americans. However, dairy is the most inadequately consumed food group in the US, with older Black adults consuming fewer than half of the 3 daily recommended servings. Therefore, this review examines the current body of evidence exploring the links between dairy intake and age-related disease risk, with a special focus on health and disparities among older Black Americans. Overall, the evidence from most systematic reviews and/or meta-analyses focused on dairy intake and musculoskeletal health suggest that higher dairy intake across the life span, and especially from fermented and fortified products, is associated with better bone and muscle health outcomes in older adults. The evidence on dairy intake and neurocognitive and immune outcomes among older adults holds significant promise for potential benefits, but most of these results are sourced from individual studies or narrative reviews and are not currently corroborated in systematic reviews or meta-analyses. Additionally, most of the research on dairy intake and age-related disease risk has been performed in White populations and can only be extrapolated to Black populations. Nonetheless, older Black populations who do not meet the DGA recommended 3 servings of dairy per day due to lactose intolerance, restrictive dietary patterns, or for other reasons, are likely falling short of several of the nutritional requirements necessary to support healthy aging.

Poor Physical Health in Caregivers of Children with ADHD or ASD and its Association with Health Risk Behaviours: NHIS 2016-2018

BACKGROUND

There is a dearth of evidence regarding physical health problems and health risk behaviours (e.g., drinking, physical inactivity, smoking, and suboptimal sleep behaviour) in caregivers of children with attention deficit hyperactivity disorder or autism spectrum disorder (CCAA). The purposes of the current study were to examine differences in physical health problems between CCAA and caregivers of children without attention deficit hyperactivity disorder and autism spectrum disorder (CCWAA) and to explore health risk behaviours associated with those problems.

METHOD

Data from the 2016-2018 National Health Interview Survey were used in the current study. 10 common physical health problems were compared between CCAA and CCWAA by using multivariable logistic regressions. In addition, in order to detect associated health risk behaviours, decision tree analysis was performed for physical health problems in CCAA.

RESULTS

Of the 10 physical health problems, caregivers of children with ADHD showed significantly higher likelihood of experiencing nine (arthritis, asthma, back pain, high cholesterol, diabetes, heart problems, hypertension, neck pain, obesity), compared to CCWAA. Caregivers of children with autism spectrum disorder (ASD) showed significantly higher likelihoods of experiencing two physical health problems compared to CCWAA. The decision tree analysis revealed that age (> 42 years), and suboptimal sleep behaviour (not 7-8 hours), and smoking (current smoker) were the frequent predictors for physical health problems in CCAA.

CONCLUSION

The results of the current study represent an important milestone in further investigating physical health problems in CCAA.

Racial, Gender, and Size Bias in a Medical Graphical Abstract Gallery: A Content Analysis

Introduction

Graphical abstracts may enhance dissemination of scientific and medical research but are also prone to reductionism and bias. We conducted a systematic content analysis of the Journal of Internal Medicine (JIM) Graphical Abstract Gallery to assess for evidence of bias.

Materials and Methods

We analyzed 140 graphical abstracts published by JIM between February 2019 and May 2020. Using a combination of inductive and deductive approaches, we developed a set of codes and code definitions for thematic, mixed-methods analysis.

Results

We found that JIM graphical abstracts disproportionately emphasized male (59.5%) and light-skinned (91.3%) bodies, stigmatized large body size, and overstated genetic and behavioral causes of disease, even relative to the articles they purportedly represented. Whereas 50.7% of the graphical surface area was coded as representing genetic factors, just 0.4% represented the social environment.

Discussion

Our analysis suggests evidence of bias and reductionism promoting normative white male bodies, linking large bodies with disease and death, conflating race with genetics, and overrepresenting genes while underrepresenting the environment as a driver of health and illness. These findings suggest that uncritical use of graphical abstracts may distort rather than enhance our understanding of disease; harm patients who are minoritized by race, gender, or body size; and direct attention away from dismantling the structural barriers to health equity.

Conclusion

We recommend that journals develop standards for mitigating bias in the publication of graphical abstracts that (1) ensure diverse skin tone and gender representation, (2) mitigate weight bias, (3) avoid racial or ethnic essentialism, and (4) attend to sociostructural contributors to disease.

Peer-Led Focus Groups Identify Barriers to Healthy Lifestyle in African American Adolescents from Baltimore City

Objectives

Black youth are disproportionately affected by the US obesity epidemic. Early-age obesity often continues into adulthood and is associated with a higher risk of diabetes, cardiovascular disease, and premature death. Few studies have incorporated community-based participatory research (CBPR) facilitated by youth to provide frank discussions among teens living in inner cities about challenges and facilitators in maintaining a healthy weight and to design teen-identified interventions.

Design

Black youth (n=10) were recruited from a Baltimore City high school during the 2019 to 2020 academic year and were trained by seasoned investigators and mentored by graduate and undergraduate students on qualitative methods using CBPR. These youth then implemented focus groups with their peers aged 15 to 18 years (10 focus groups of 10 teens each). Topics included healthy lifestyle knowledge, behaviors, attitudes, and suggested interventions. Content analyses were conducted using dual-rater techniques.

Results

Focus group themes yielded strengths and challenges of weight maintenance for Black youth at various levels, including in their personal lives, families, school, and community. Themes also suggested several technology-based possibilities using social media to reach Black youth about healthy living practices.

Conclusions

Engagement of Black youth in CBPR projects can yield valuable data to design more culturally responsive and developmentally appropriate interventions. Youth are competent collectors of information to identify needed changes in their schools/communities and about the use of technology/social media to facilitate improved health practices among their peers and should be involved early in the process of developing targeted obesity prevention interventions and/or programs.

Pathophysiology of type 2 diabetes in sub-Saharan Africans

Sub-Saharan Africa (SSA) is the region with the highest projected rates of increase in type 2 diabetes (129% by 2045), which will exacerbate the already high prevalence of type 2 diabetes complications and comorbidities in SSA. In addition, SSA is grappling with poverty-related health problems and infectious diseases and is also undergoing the most rapid rates of urbanisation globally. These socioenvironmental and lifestyle factors may interact with genetic factors to alter the pathophysiological sequence leading to type 2 diabetes in sub-Saharan African populations. Indeed, current evidence from SSA and the diaspora suggests that the pathophysiology of type 2 diabetes in Black Africans is different from that in their European counterparts. Studies from the diaspora suggest that insulin clearance is the primary defect underlying the development of type 2 diabetes. We propose that, among Black Africans from SSA, hyperinsulinaemia due to a combination of both increased insulin secretion and reduced hepatic insulin clearance is the primary defect, which promotes obesity and insulin resistance, exacerbating the hyperinsulinaemia and eventually leading to beta cell failure and type 2 diabetes. Nonetheless, the current understanding of the pathogenesis of type 2 diabetes and the clinical guidelines for preventing and managing the disease are largely based on studies including participants of predominately White European ancestry. In this review, we summarise the existing knowledge base and data from the only non-pharmacological intervention that explores the pathophysiology of type 2 diabetes in SSA. We also highlight factors that may influence the pathogenesis of type 2 diabetes in SSA, such as social determinants, infectious diseases and genetic and epigenetic influences.

Obesity Pillars Roundtable: Body mass index and body composition in Black and Female individuals. Race-relevant or racist? Sex-relevant or sexist?

Background

Body mass index (BMI or weight in kilograms/height in meters2) is the most common metric to diagnose overweight and obesity. However, a body composition analysis more thoroughly assesses adiposity, percent body fat, lean body mass (i.e., including skeletal muscle), and sometimes bone mineral density. BMI is not an accurate assessment of body fat in individuals with increased or decreased muscle mass; the diagnostic utility of BMI in individuals is also influenced by race and sex.

Methods

Previous Obesity Pillars Roundtables addressed the diagnostic limitations of BMI, the importance of android and visceral fat (especially among those with South and East Asian ancestry), and considerations of obesity among individuals who identify as Hispanic, diverse in sexual-orientation, Black, Native American, and having ancestry from the Mediterranean and Middle East regions. This roundtable examines considerations of BMI in Black and female individuals.

Results

The panelists agreed that body composition assessment was a more accurate measure of adiposity and muscle mass than BMI. When it came to matters of race and sex, one panelist felt: "race is a social construct and not a defining biology." Another felt that: "BMI should be a screening tool to prompt further evaluation of adiposity that utilizes better diagnostic tools for body composition." Regarding bias and misperceptions of resistance training in female individuals, another panelist stated: "I have spent my entire medical career taking care of women and have never seen a woman unintentionally gain 'too much' muscle mass and bulk up from moderate strength training."

Conclusions

Conveying the importance of race and sex regarding body composition has proven challenging, with the discussion sometimes devolving into misunderstandings or misinformation that may be perceived as racist or sexist. Body composition analysis is the ultimate diagnostic equalizer in addressing the inaccuracies and biases inherent in the exclusive use of BMI.

Mitochondrial Phenotype as a Driver of the Racial Dichotomy in Obesity and Insulin Resistance

African Americans (AA) are disproportionately burdened by metabolic diseases. While largely unexplored between Caucasian (C) and AA, differences in mitochondrial bioenergetics may provide crucial insight to mechanisms for increased susceptibility to metabolic diseases. AA display lower total energy expenditure and resting metabolic rate compared to C, but paradoxically have a higher amount of skeletal muscle mass, suggestive of inherent energetic efficiency differences between these races. Such adaptations would increase the chances of overnutrition in AA; however, these disparities would not explain the racial difference in insulin resistance (IR) in healthy subjects. Hallmarks associated with insulin resistance (IR), such as reduced mitochondrial oxidative capacity and metabolic inflexibility are present even in healthy AA without a metabolic disease. These adaptations might be influential of mitochondrial “substrate preference” and could play a role in disproportionate IR rates among races. A higher glycolytic flux and provision of shuttles transferring electrons from cytosol to mitochondrial matrix could be a contributing factor in development of IR via heightened reactive oxygen species (ROS) production. This review highlights the above concepts and provides suggestions for future studies that could help delineate molecular premises behind potential impairments in insulin signaling and metabolic disease susceptibility in AA.

Migraine, Brain Glucose Metabolism and the "Neuroenergetic" Hypothesis: A Scoping Review

Increasing evidence suggests that migraine may be the result of an impaired brain glucose metabolism. Several studies have reported brain mitochondrial dysfunction, impaired brain glucose metabolism and gray matter volume reduction in specific brain areas of migraineurs. Furthermore, peripheral insulin resistance, a condition demonstrated in several studies, may extend to the brain, leading to brain insulin resistance. This condition has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis, mainly during high metabolic demand. This scoping review examines the clinical, epidemiologic and pathophysiologic data supporting the hypothesis that abnormalities in brain glucose metabolism may generate a mismatch between the brain's energy reserve and metabolic expenditure, triggering migraine attacks. Moreover, alteration in glucose homeostasis could generate a chronic brain energy deficit promoting migraine chronification. Lastly, insulin resistance may link migraine with its comorbidities, like obesity, depression, cognitive impairment and cerebrovascular diseases. PERSPECTIVE: Although additional experimental studies are needed to support this novel "neuroenergetic" hypothesis, brain insulin resistance in migraineurs may unravel the pathophysiological mechanisms of the disease, explaining the migraine chronification and connecting migraine with comorbidities. Therefore, this hypothesis could elucidate novel potential approaches for migraine treatment.

Insulin sensitivity and kinetics in African American and White people with obesity: Insights from different study protocols

OBJECTIVE

Studies that used an intravenous glucose tolerance test (IVGTT) have suggested that race is an important modulator of insulin sensitivity, β-cell function, and insulin clearance. However, the validity of the IVGTT has been challenged.

METHODS

This study assessed insulin sensitivity and insulin kinetics in non-Hispanic White (NHW, n = 29) and African American (AA, n = 14) people with obesity by using a hyperinsulinemic-euglycemic pancreatic clamp with glucose tracer infusion, an oral glucose tolerance test (OGTT), and an IVGTT.

RESULTS

Hepatic insulin sensitivity was better in AA participants than in NHW participants. Muscle insulin sensitivity, insulin secretion in relation to plasma glucose during the OGTT, and insulin clearance during basal conditions during the hyperinsulinemic-euglycemic pancreatic clamp and during the OGTT were not different between AA participants and NHW participants. The acute insulin response to the large glucose bolus administered during the IVGTT was double in AA participants compared with NHW participants because of increased insulin secretion and reduced insulin clearance.

CONCLUSIONS

AA individuals are not more insulin resistant than NHW individuals, and the β-cell response to glucose ingestion and postprandial insulin clearance are not different between AA individuals and NHW individuals. However, AA individuals have greater insulin secretory capacity and reduced insulin clearance capacity than NHW individuals and might be susceptible to hyperinsulinemia after consuming very large amounts of glucose.

Sex Differences in the Associations of Nutrient Patterns with Total and Regional Adiposity: A Study of Middle-Aged Black South African Men and Women

The study evaluated the association between nutrient patterns with body fat and regional adiposity in middle-aged black South African (SA) men and women and determined if this differed by sex. Body fat and regional adiposity (dual-energy x-ray absorptiometry), and dietary intake (7-day quantified food frequency questionnaire) were measured in black SA men (n = 414) and women (n = 346). Using principal component analysis, nutrient patterns were computed from 25 nutrients in the combined sample. Four nutrient patterns were extracted, explaining 67% of the variance in nutrient intake. Animal and fat, as well as the vitamin C, sugar, and potassium driven patterns, were positively associated with total adiposity. In contrast, the retinol and vitamin B12 pattern was associated with the centralisation of fat. Notably, the strength of the association between the animal-driven nutrient pattern and BMI was greater in men (1.14 kg/m², 95% CI (0.63–1.66)) than in women (0.81 kg/m², 95% CI (0.25–1.36)) (P_int = 0.017). In contrast, the plant-driven pattern was associated with higher abdominal subcutaneous adipose tissue (SAT) in women (44 cm², 95% CI (22–67)) but not men (P_int = 1.54 × 10⁻⁴). These differences suggest that although men and women have similar nutrient patterns, their associations with the whole body and regional body fat are different.

Genetic risk score prediction of leg fat and insulin sensitivity differs by race/ethnicity in early pubertal children

BACKGROUND

In the United States, the underlying reasons for racial/ethnic disparities in type 2 diabetes risk remain unclear. However, differences in genetic risk for insulin resistance and peripheral adipose tissue distribution may be contributing factors.

OBJECTIVE

To investigate racial/ethnic differences in associations of genetic risk for insulin resistance with leg fat and insulin sensitivity in a cohort of American children.

METHODS

Participants were healthy European-American (n = 83), African-American (n = 79) and Hispanic-American (n = 74) children aged 7-12 years. Genetic risk scores were derived from published variants associated with insulin resistance phenotypes in European adults. Body composition was assessed using dual-energy X-ray absorptiometry. Insulin sensitivity was determined from the frequently sampled intravenous glucose tolerance test and minimal modelling. Statistical models were adjusted for age, sex, pubertal stage and body composition.

RESULTS

In the combined cohort, risk score was inversely associated with insulin sensitivity (p = 0.033) but not leg fat (p = 0.170). Within Hispanic Americans, risk score was inversely associated with insulin sensitivity (p = 0.027) and leg fat (p = 0.005), while associations were non-significant in European and African Americans (p > 0.200).

CONCLUSIONS

The higher type 2 diabetes risk observed among Hispanic Americans may have a genetic basis related to an inability to store lipid in peripheral adipose tissue.

Diabetes Mellitus and Its Metabolic Complications: The Role of Adipose Tissues

Many approaches have been used in the effective management of type 2 diabetes mellitus. A recent paradigm shift has focused on the role of adipose tissues in the development and treatment of the disease. Brown adipose tissues (BAT) and white adipose tissues (WAT) are the two main types of adipose tissues with beige subsets more recently identified. They play key roles in communication and insulin sensitivity. However, WAT has been shown to contribute significantly to endocrine function. WAT produces hormones and cytokines, collectively called adipocytokines, such as leptin and adiponectin. These adipocytokines have been proven to vary in conditions, such as metabolic dysfunction, type 2 diabetes, or inflammation. The regulation of fat storage, energy metabolism, satiety, and insulin release are all features of adipose tissues. As such, they are indicators that may provide insights on the development of metabolic dysfunction or type 2 diabetes and can be considered routes for therapeutic considerations. The essential roles of adipocytokines vis-a-vis satiety, appetite, regulation of fat storage and energy, glucose tolerance, and insulin release, solidifies adipose tissue role in the development and pathogenesis of diabetes mellitus and the complications associated with the disease.

Contribution of Adipose Tissue Oxidative Stress to Obesity-Associated Diabetes Risk and Ethnic Differences: Focus on Women of African Ancestry

Adipose tissue (AT) storage capacity is central in the maintenance of whole-body homeostasis, especially in obesity states. However, sustained nutrients overflow may dysregulate this function resulting in adipocytes hypertrophy, AT hypoxia, inflammation and oxidative stress. Systemic inflammation may also contribute to the disruption of AT redox equilibrium. AT and systemic oxidative stress have been involved in the development of obesity-associated insulin resistance (IR) and type 2 diabetes (T2D) through several mechanisms. Interestingly, fat accumulation, body fat distribution and the degree of how adiposity translates into cardio-metabolic diseases differ between ethnicities. Populations of African ancestry have a higher prevalence of obesity and higher T2D risk than populations of European ancestry, mainly driven by higher rates among African women. Considering the reported ethnic-specific differences in AT distribution and function and higher levels of systemic oxidative stress markers, oxidative stress is a potential contributor to the higher susceptibility for metabolic diseases in African women. This review summarizes existing evidence supporting this hypothesis while acknowledging a lack of data on AT oxidative stress in relation to IR in Africans, and the potential influence of other ethnicity-related modulators (e.g., genetic-environment interplay, socioeconomic factors) for consideration in future studies with different ethnicities.

Race Based Medicine, Colorblind Disease: How Racism in Medicine Harms Us All

The genome between socially constructed racial groups is 99.5%-99.9% identical; the 0.1%-0.5% variation between any two unrelated individuals is greatest between individuals in the same racial group; and there are no identifiable racial genomic clusters. Nevertheless, race continues to be used as a biological reality in health disparities research, medical guidelines, and standards of care reinforcing the notion that racial and ethnic minorities are inferior, while ignoring the health problems of Whites. This article discusses how the continued misuse of race in medicine and the identification of Whites as the control group, which reinforces this racial hierarchy, are examples of racism in medicine that harm all us. To address this problem, race should only be used as a factor in medicine when explicitly connected to racism or to fulfill diversity and inclusion efforts.

Characteristics and resolution of hypertension in obese African American bariatric cohort

Weight reduction continues to be first-line therapy in the treatment of hypertension (HTN). However, the long-term effect of bariatric malabsorptive surgical techniques such as Roux-en-Y Gastric Bypass (RYGB) surgery in the management of hypertension (HTN) is less clear. African Americans (AA) are disproportionately affected by obesity and hypertension and have inconsistent outcomes after bariatric surgery (BS). Despite a plethora of bariatric literature, data about characteristics of a predominantly AA bariatric hypertensive cohort including hypertension in obese (HIO) are scarce and underreported. The aims of this study were, (1) to describe the preoperative clinical characteristics of HIO with respect to HTN status and age, and (2) to identify predictors of HTN resolution one year after RYGB surgery in an AA bariatric cohort enrolled at the Howard University Center for Wellness and Weight Loss Surgery (HUCWWS). In the review of 169 AA bariatric patients, the average BMI was 48.50 kg/m² and the average age was 43.86 years. Obese hypertensive patients were older (46 years vs. 37.89 years; p < .0001); had higher prevalence of diabetes mellitus (DM, 43.09% vs. 10.87%; p < .0001) and dyslipidemia (38.2% vs. 13.04%; p 0.002). Hypertensive AA who were taking ≥ 2 antihypertensive medications prior to RYGB were 18 times less likely to experience HTN resolution compared to hypertensive AA taking 0–1 medications, who showed full or partial response. Also, HIO was less likely to resolve after RYGB surgery in patients who needed ≥ 2 antihypertensive medications prior to surgical intervention.

Race, racism and disparities in obesity rates in the US

Click here to view the Letter to the Editor by Gower et al.