Obesity, levels of lipids and glucose, and smoking among Navajo adolescents

Group Randomized Trial of Healthy Eating and Gardening Intervention in Navajo Elementary Schools (Yéego!)

Introduction

Few healthy eating, school-based interventions have been rigorously evaluated in American Indian communities. Gardening and healthy eating are priorities in the Navajo Nation. Collaborations between researchers and local partners supported the design and implementation of this project.

Design

The Yéego! Healthy Eating and Gardening Study was a group-randomized controlled trial to evaluate a school-based healthy eating and gardening intervention in 6 schools in the Navajo Nation. Schools were randomized 1:2 to intervention or comparison.

Setting/participants

The Shiprock and Tsaile/Chinle areas in the Navajo Nation were selected. Elementary schools were screened for eligibility. All students in third and fourth grades were invited to participate in the assessments.

Intervention

Delivered during 1 school year in the intervention schools, the intervention included a culturally relevant nutrition and gardening curriculum and a school garden.

Main outcome measures

Student self-efficacy for eating fruits and vegetables, student self-efficacy for gardening, and student healthy foods score from a modified Alternative Healthy Eating Index were assessed in third and fourth graders at the beginning and end of a school year affected by the COVID-19 pandemic. Primary analyses used repeated measures linear mixed models accounting for students nested within schools to estimate the intervention effect and 95% CIs.

Results

Students in the intervention schools had self-efficacy scores for eating fruits and vegetables that were 0.22 points greater (95% CI=0.04, 0.41) than those in the comparison schools, although the student healthy foods score increased in the intervention schools by 2.0 (95% CI=0.4, 3.6); the differential change was modest at 1.7 (95% CI=-0.3, 3.7). The self-efficacy to grow fruits and vegetables in the school garden increased among those in the intervention schools (OR=1.92; 95% CI=1.02, 3.63) but not significantly more than it increased in the comparison schools (OR=1.29; 95% CI=0.60, 2.81).

Conclusions

The intervention was efficacious in improving self-efficacy for eating fruits and vegetables among third- and fourth-grade students over a school year. The findings warrant further evaluation of the intervention in larger-group randomized trials with schools in Navajo communities.

Trial registration

This study is registered at clinicaltrials.gov NCT03778021.

Apolipoprotein B polymorphism distribution among a sample of obese Egyptian females with visceral obesity and its influence on lipid profile

Background

Regional distribution of adipose tissue is more important than total amount of body fat in predicting complications associated with obesity. Apolipoprotein B (Apo B) plays a central role in lipid metabolism.

Aim

To investigate the importance of the XbaI polymorphism of Apo B gene (C7673T) as risk factor for visceral obesity and its influence on lipid profile.

Subjects and methods

Total of 122 obese adult females (BMI ⩾ 30 kg/m²): 56 of them with visceral obesity (⩾7 cm by abdominal Ultrasound) and 66 without visceral obesity and 36 age matched non-obese (BMI ⩽ 25 kg/m²) without visceral obesity were studied. Anthropometric assessment, body composition, visceral obesity and lipid profile evaluation were attempted. Genetic analysis of Apo B XbaI was performed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP).

Results

Visceral obesity was associated significantly with the presence of the heterozygous (CT) genotype of the XbaI Apo B gene (p < 0.001). Frequency of homozygous (CC) was significantly the least genotype found in females with visceral obesity, while homozygote (TT) genotype was more frequent in those without visceral obesity. T allele (about 70%) was more frequent than C allele (about 30%) in all groups. Significant lowest values of visceral obesity, triglyceride and HDL-C were associated with the presence of (CC) genotype and the highest values were associated with the presence of the heterozygous (CT) genotype; except HDL-C with (TT) genotype.

Conclusions

Study reveals considerable association of Apo B XbaI gene polymorphism with visceral obesity and some lipid profile parameters (TG and HDL-C) among Egyptian females.

Association of apolipoprotein B XbaI gene polymorphism and lipid profile in northern Indian obese

BACKGROUND:

Over the last few decades, obesity, diabetes, and hypertension have become main health evils. The health problems of obesity are well-recognized. However, the fact that all obese individuals are not at the same risk of developing a disease is also recognized. The apolipoprotein B (APOB) plays a central role in lipid metabolism. So we compare the association of APOB XbaI gene polymorphism and lipid profile total in obese north Indian population.

MATERIALS AND METHODS:

A total of 132 obese (body mass index [BMI] >25 kg/m²) and 132 age matched non-obese (BMI ≤ 25 kg/m²) subjects were studied after taking detailed clinical profile. Lipid profile in serum/plasma was done using commercial kits. Genetic analysis of APOB XbaI was done using Polymerase Chain Reaction-Restriction Fragment Leanth polymorphism (PCR-RFLP).

STATISTICAL ANALYSIS:

Statistical analysis was performed by Statistical Package for the Social Sciences (SPSS) (version 11.5) software (IBM Corporation). All continuous variables were expressed as mean ± SD and tested by analysis of variance test. Comparisons of categorical variables were assessed using χ² tests or Fisher's exact test. P < 0.05 was considered as significant.

RESULTS:

Analysis showed that obese subjects had significantly higher value of the waist-to-hip ratio, blood pressure (systolic and diastolic), and lipid profile. In APOB XbaI gene polymorphism, we did not find significant differences in genotype or allele frequencies. Moreover, none of the studied metabolic parameters (lipid profile) showed any association with the gene polymorphism.

CONCLUSIONS:

Study reveals no considerable association of APOB XbaI gene polymorphism with obesity and lipid profile in north Indians.

Cigarette smoking and its association with serum lipid/lipoprotein among Chinese nonagenarians/centenarians

Objective

Cigarette smoking had been confirmed as an increased risk for dyslipidemia, but none of the evidence was from long-lived population. In present study, we detected relationship between cigarette smoking habits and serum lipid/lipoprotein (serum Triglyceride (TG), Total cholesterol (TC), Low-density lipoprotein (LDL) and high-density lipoprotein (HDL)) among Chinese Nonagenarians/Centenarian.

Methods

The present study analyzed data from the survey that was conducted on all residents aged 90 years or more in a district, there were 2,311,709 inhabitants in 2005. Unpaired Student’s t test, χ² test, and multiple logistic regression were used to analyze datas.

Results

The individuals included in the statistical analysis were 216 men and 445 women. Current smokers had lower level of TC (4.05 ± 0.81 vs. 4.21 ± 0.87, t = 2.403, P = 0.017) and lower prevalence of hypercholesteremia (9.62% vs. 15.13%, χ² = 3.018,P = 0.049) than nonsmokers. Unadjusted and adjusted multiple logistic regressions showed that cigarette smoking was not associated with risk for abnormal serum lipid/lipoprotein.

Conclusions

In summary, we found that among Chinese nonagenarians/centenarians, cigarette smoking habits were not associated with increased risk for dyslipidemia, which was different from the association of smoking habits with dyslipidemia in general population.

Overweight and obesity among North American Indian infants, children, and youth

The frequency of overweight and obesity among North American Indian children and youth exceeds that of other ethnic groups in the United States. This observation is based on studies using body mass index as the primary measure of overweight and obesity. In the mid-20th century, there were regional differences among North American Indian groups in sub-adults' size and shape and only a few Southwestern groups were characterized by high rates of overweight and obesity. In most populations, the high prevalence of overweight and obesity developed in the last decades of the 20th century. Childhood obesity may begin early in life as many studies report higher birth weights and greater weight-for-height in the preschool years. Contributing factors include higher maternal weights, a nutritional transition from locally caught or raised foods to store bought items, psychosocial stress associated with threats to cultural identity and national sovereignty, and exposure to obesogenic pollutants, all associated to some degree with poverty. Obesity is part of the profile of poor health among Native Americans in the US and Canada, and contributes to woefully high rates of diabetes, cardiovascular disease, and early mortality. Interventions that are culturally appropriate are needed to reduce weights at all points in the lifespan.

Diabetes in Navajo youth: prevalence, incidence, and clinical characteristics: the SEARCH for Diabetes in Youth Study

OBJECTIVE

To estimate the prevalence and incidence of diabetes, clinical characteristics, and risk factors for chronic complications among Navajo youth, using data collected by the SEARCH for Diabetes in Youth Study (SEARCH study).

RESEARCH DESIGN AND METHODS

The SEARCH study identified all prevalent cases of diabetes in 2001 and all incident cases in 2002-2005 among Navajo youth. We estimated denominators with the user population for eligible health care facilities. Youth with diabetes also attended a research visit that included questionnaires, physical examination, blood and urine collection, and extended medical record abstraction.

RESULTS

Diabetes is infrequent among Navajo youth aged <10 years. However, both prevalence and incidence of diabetes are high in older youth. Among adolescents aged 15-19 years, 1 in 359 Navajo youth had diabetes in 2001 and 1 in 2,542 developed diabetes annually. The vast majority of diabetes among Navajo youth with diabetes is type 2, although type 1 diabetes is also present, especially among younger children. Navajo youth with either diabetes type were likely to have poor glycemic control, high prevalence of unhealthy behaviors, and evidence of severely depressed mood. Youth with type 2 diabetes had more metabolic factors associated with obesity and insulin resistance (abdominal fat deposition, dyslipidemia, and higher albumin-to-creatinine ratio) than youth with type 1 diabetes.

CONCLUSIONS

Our data provide evidence that diabetes is an important health problem for Navajo youth. Targeted efforts aimed at primary prevention of diabetes in Navajo youth and efforts to prevent or delay the development of chronic complications among those with diabetes are warranted.

Occupational exposure to mineral fibres. Biomarkers of oxidative damage and antioxidant defence and associations with DNA damage and repair

In order to study the effect of mineral wool exposure on oxidative DNA damage and lipid peroxidation, an epidemiological study was conducted in a mineral wool factory in Slovakia. Altogether 141 subjects were investigated (21-58 years old), 43 controls (20 men and 23 women: 27 non-smokers, 16 smokers) and 98 exposed (75 men and 23 women: 61 non-smokers, 37 smokers). We found higher malondialdehyde (MDA) levels in the group of all exposed workers (P = 0.025) and in exposed non-smokers (P = 0.003) and a significantly suppressed activity of ceruloplasmin oxidase (P = 0.02, P < 0.02, respectively) and catalase (CAT) (P = 0.04, P = 0.01, respectively) in these groups. The activity of glutathione S-transferase (GST) was affected by exposure to mineral wool; levels were significantly lower in all exposed subjects (P = 0.04), in the exposed non-smokers (P = 0.03) and in exposed men (P < 0.01). Concentrations of vitamin C in plasma and the ferric-reducing activity of plasma (FRAP) were not affected by the mineral wool exposure. There was a significant negative correlation between the activity of glutathione peroxidase (GPX) and MDA in the whole group (P < 0.01) and in the exposed group and between CAT activity and MDA in all subjects (P < 0.01). GST activity correlated inversely with oxidized pyrimidines in lymphocyte DNA, in almost all subgroups. We found significant negative correlations between DNA repair and GPX in all subjects (P = 0.03) as well as in control men (P < 0.03) and between DNA repair and CAT in all control subjects (P < 0.02) and in control men (P < 0.01). Interestingly, we found a positive correlation between DNA repair and MDA in all subjects (P < 0.01) and in all exposed subjects (P < 0.03). The presented results indicate that mineral wool exposure induces an increase in oxidative damage to biomolecules especially in the group of male non-smokers. However, optimal levels of antioxidants could have a protective effect. Biomarkers such as MDA, antioxidant enzymes and antioxidant vitamins measured in blood may be useful biomarkers of oxidative stress and antioxidant protection. We do not recommend FRAP as a marker of antioxidant status as interference from other constituents can provide false or confusing results. Our study supports the idea that there might also be other mechanisms by which antioxidant enzymes (especially GST) protect cells against oxidative DNA damage.

Ethics in public health research: changing patterns of mortality among American Indians

Mortality rates for American Indians (including Alaska Natives) declined for much of the 20th century, but data published by the Indian Health Service indicate that since the mid-1980s, age-adjusted deaths for this population have increased both in absolute terms and compared with rates for the White American population. This increase appears to be primarily because of the direct and indirect effects of type 2 diabetes. Despite increasing appropriations for the Special Diabetes Program for Indians, per capita expenditures for Indian health, including third-party reimbursements, remain substantially lower than those for other Americans and, when adjusted for inflation, have been essentially unchanged since the early 1990s. I argue that inadequate funding for health services has contributed significantly to the increased death rate.

Lipid and lipoprotein profiles and prevalence of dyslipidemia in Mexican adolescents

The objective of the study was to determine the prevalence of different forms of dyslipidemia in an urban population of Mexican adolescents. A cross-sectional study was conducted in 1846 students from 8 randomly selected public junior high schools in Mexico City. Anthropometry, blood pressure, and 12-hour fasting lipids and lipoproteins were measured. We studied 770 male and 1076 female adolescents (13.2 +/- 1 years). The most prevalent dyslipidemia was low high-density lipoprotein cholesterol (HDL-C) (<35 mg/dL) either combined with other abnormalities (17.5% for male and 12.9% for female subjects, P < .001) or isolated (13.5% and 9.6% for male and female subjects, respectively, P < .001). Obese subjects showed the highest prevalence of low HDL-C (47.2% for male and 34.4% for female subjects) and of high total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG) (19.4%, 27.8%, and 36.1%, respectively, for male subjects; 9.8%, 13.1%, and 24.6%, respectively, for female subjects). Multiple regression analysis showed that waist circumference was negatively associated with HDL-C and positively associated with LDL-C and TG levels, whereas Tanner stages were negatively associated but sex was positively associated with total cholesterol, LDL-C, and TG concentrations. As in Mexican adults, low HDL-C and high TG levels were the most prevalent dyslipidemias. Increased blood lipids over long periods suggest that, as adults, these adolescents will be facing a higher risk for atherosclerosis.

The gender insulin hypothesis: why girls are born lighter than boys, and the implications for insulin resistance

Girls are born lighter than boys. The consistency of this observation across different populations is striking, suggesting that it may have fundamental significance for those conditions linked with lower birth weight, such as diabetes. Previous hypotheses relating low birth weight to subsequent diabetes have addressed differences in insulin resistance within the sexes, not between them. Here, we propose that gender-specific genes affecting insulin sensitivity are responsible for the gender difference in birth weight--the genetically more insulin resistant female fetus is less responsive to the trophic effects of insulin and is therefore smaller. These genes also render female subjects more susceptible to diabetes, explaining why reports of type 2 diabetes (T2D) in younger populations show a female preponderance. Consistent with our proposal, concentrations of insulin and/or its propeptides are higher at birth in female populations and they are intrinsically more insulin resistant throughout life, with attendant impact on their metabolism, and the regressions describing the relationship between insulin resistance and adiposity in female and male subjects have similar gradients, but different constants. These gender-specific genes have a demonstrable impact on fetal growth and insulin resistance. Diabetes and cardiovascular disease are thought to be driven by insulin resistance, and the observations reported here may help to focus the search for genes that control it.

Genotype-by-sex interaction in the aetiology of type 2 diabetes mellitus: support for sex-specific quantitative trait loci in Hypertension Genetic Epidemiology Network participants

AIMS/HYPOTHESIS

While there are sex-related differences in both the prevalence of type 2 diabetes mellitus and disease risk factors, there is only limited research on sex-specific influences on type 2 diabetes aetiology within the same study population. Thus, we assessed genotype-by-sex interaction using a liability threshold model in an attempt to localise sex-specific type 2 diabetes quantitative trait loci (QTLs).

SUBJECTS, MATERIALS AND METHODS

Hypertensive siblings and their offspring and/or parents in the Hypertension Genetic Epidemiology Network of the Family Blood Pressure Program were recruited from five field centres. The diabetic phenotype was adjusted for race, study centre, age and non-linear age effects. In total, 567 diabetic individuals were identified in 385 families. Variance component linkage analyses in the combined sample and stratified by sex and race were performed (SOLAR program) using race-specific marker allele frequencies derived from a random sample of participants at each centre.

RESULTS

We observed a QTL-specific genotype-by-sex interaction (p=0.009) on chromosome 17 at 31 cM, with females displaying a robust adjusted logarithm of odds (LOD) of 3.0 compared with 0.2 in males and 1.3 in the combined sample. Three additional regions demonstrating suggestive evidence for linkage were detected: chromosomes 2 and 5 in the female sample and chromosome 22 (adjusted LOD=1.9) in the combined sample.

CONCLUSIONS/INTERPRETATION

These findings suggest that multiple genes may regulate susceptibility to type 2 diabetes, demonstrating the importance of considering the interaction of genes and environment in the aetiology of common complex traits.

The burden of diabetes mellitus among US youth: prevalence estimates from the SEARCH for Diabetes in Youth Study

OBJECTIVE

Our goal was to estimate the prevalence of diabetes mellitus in youth <20 years of age in 2001 in the United States, according to age, gender, race/ethnicity, and diabetes type.

METHODS

The SEARCH for Diabetes in Youth Study is a 6-center observational study conducting population-based ascertainment of physician-diagnosed diabetes in youth. Census-based denominators for 4 geographically based centers and enrollment data for 2 health plan-based centers were used to calculate prevalence. Age-, gender-, and racial/ethnic group-specific prevalence rates were multiplied by US population counts to estimate the total number of US youth with diabetes.

RESULTS

We identified 6379 US youth with diabetes in 2001, in a population of approximately 3.5 million. Crude prevalence was estimated as 1.82 cases per 1000 youth, being much lower for youth 0 to 9 years of age (0.79 cases per 1000 youth) than for those 10 to 19 years of age (2.80 cases per 1000 youth). Non-Hispanic white youth had the highest prevalence (1.06 cases per 1000 youth) in the younger group. Among 10- to 19-year-old youth, black youth (3.22 cases per 1000 youth) and non-Hispanic white youth (3.18 cases per 1000 youth) had the highest rates, followed by American Indian youth (2.28 cases per 1000 youth), Hispanic youth (2.18 cases per 1000 youth), and Asian/Pacific Islander youth (1.34 cases per 1000 youth). Among younger children, type 1 diabetes accounted for > or = 80% of diabetes; among older youth, the proportion of type 2 diabetes ranged from 6% (0.19 cases per 1000 youth for non-Hispanic white youth) to 76% (1.74 cases per 1000 youth for American Indian youth). We estimated that 154,369 youth had physician-diagnosed diabetes in 2001 in the United States.

CONCLUSIONS

The overall prevalence estimate for diabetes in children and adolescents was approximately 0.18%. Type 2 diabetes was found in all racial/ethnic groups but generally was less common than type 1, except in American Indian youth.

Type 2 diabetes mellitus in youth: the complete picture to date

Type 2 diabetes mellitus is a heterogeneous condition in which the clinical manifestation of hyperglycemia is a reflection of the impaired balance between insulin sensitivity and insulin secretion. Clinical experience and research in youth type 2 diabetes mellitus are in an early stage because of the relative novelty of the condition in pediatrics. This article discusses the amassed information in type 2 diabetes mellitus of youth to date with respect to the epidemiology, pathophysiology, risk factors, clinical presentation, screening, and management strategies.

Type 2 diabetes mellitus in children and adolescents

Over the last decade, there has been an alarming increase of Type 2 diabetes mellitus (T2DM) in youths, concomitant with the rise of obesity in this age group. T2DM is a progressive disease with a gradual increase in insulin resistance associated later with a decline in insulin secretion with fasting hyperglycemia. Prevalence of T2DM in children is mostly linked to some risk factors: obesity and sedentary lifestyle, puberty, membership of ethnic minorities, features of insulin resistance, family history of T2DM, female gender and perinatal factors. Prevention is essential and can be considered a public health approach directed to the general population. Treatment of T2DM in youth is complex and based on different strategies: diet, exercise and pharmacotherapy. An appropriated intervention program must be started early, in order to prevent or retard the progression of the disease and associated comorbidities.

Annual incidence and clinical characteristics of type 2 diabetes in children as detected by urine glucose screening in the Tokyo metropolitan area

OBJECTIVE

This study investigates the annual incidence and clinical characteristics of type 2 diabetes among school-aged children as detected by urine glucose screening from 1974 to 2002 in the Tokyo metropolitan area.

RESEARCH DESIGN AND METHODS

In total, 8,812,356 school children were examined for glucosuria. Morning urine was used for the analysis. When the urine was positive for glucose, an oral glucose tolerance test was carried out to confirm diabetes.

RESULTS

In all, 232 students were identified to have type 2 diabetes. The overall annual incidence of type 2 diabetes was 2.63/100,000. The annual incidence after 1981 was significantly higher than that before 1980 (1.73 vs. 2.76/100,000, P < 0.0001). The annual incidence was significantly higher for junior high school students compared with primary school students (0.78 vs. 6.43/100,000, P < 0.0001). The overall male-to-female ratio of students with type 2 diabetes was 1.0:1.19 (P = 0.296), but it was 1.0:1.56 (P = 0.278) for primary school students. Overall, 83.4% of children with diabetes were obese (> or = 20% overweight). However, nonobese girls (<20% overweight) with diabetes accounted for 23.0% of the patients, whereas markedly obese boys (> or = 40% overweight) accounted for 61.5% of the patients. The frequency of a family history of type 2 diabetes in second- and first-degree relatives was 56.5%.

CONCLUSIONS

We confirmed that the incidence of young people with type 2 diabetes increased after 1981 in the Tokyo metropolitan area. The increase in the frequency of this disorder seemed to be strongly related to an increasing prevalence of obesity. Age and genetic susceptibility may be associated with the occurrence of type 2 diabetes.

Overweight in children: definitions, measurements, confounding factors, and health consequences

The epidemic of childhood overweight continues to grow at staggering rates, increasing nearly four-fold between 1963 and 2000. Children that are overweight are more apt to be overweight adults and are more likely to suffer adverse health consequences associated with excess weight. Nurses have a unique presence in the healthcare environment to assess children for overweight, provide parent/child nutritional education, and conduct obesity-related research. This article provides an overview of the current body of literature surrounding the definition and measurement of overweight and the morbidity association with childhood overweight.

Growth status and obesity of Hopi children

The purpose of this study was to examine the growth status and prevalence of underweight, overweight, and obesity in Hopi children. Subjects were 263 (117 males, 146 females) Hopi children 6-12 years of age. Stature and mass were measured and the body mass index (BMI) was calculated. Body size variables were plotted relative to age- and sex-specific reference data and the prevalence rates for underweight, overweight, and obesity were estimated using the BMI as the criterion. Age-specific sex differences were compared using independent samples t-tests. In both sexes, mean age-specific stature appeared to be relatively stable around the 50th percentile of reference values. Mean age-specific mass appeared to be relatively stable between the 50th and 90th percentiles of the reference values, while the mean BMI tended to fluctuate about the 85th percentile. Approximately 23% of Hopi children were classified as overweight and an additional 24% were classified as obese. Only two subjects were categorized as underweight. The results are consistent with other reports that childhood obesity is a serious public health concern among Native Americans. Further study is warranted to examine the causes of the high prevalence rates of pediatric obesity among Native Americans and the effectiveness of prevention and intervention programs.

Girls at five are intrinsically more insulin resistant than boys: The Programming Hypotheses Revisited--The EarlyBird Study (EarlyBird 6)

OBJECTIVE

Recent studies of type 2 diabetes in young populations consistently show a predominance of affected girls over boys. Girls are more insulin resistant than boys. We aimed in the present report to establish how much of the sex difference in insulin resistance is intrinsic.

METHODS

EarlyBird is a community-based, nonintervention cohort study of 307 healthy children from school entry at age 5 years. It asks the question: which children are insulin resistant and why? Anthropometric measures, physical activity, resting energy expenditure, and insulin resistance and its metabolic correlates were measured.

RESULTS

At 5 years, insulin resistance was 35% higher in girls than in boys. Girls carried 26% more subcutaneous fat despite similar body weights. However, after correcting for anthropometric variables and physical activity, girls remained 33% more insulin resistant than boys. Triglycerides were significantly higher in girls, and high-density lipoprotein cholesterol and sex hormone-binding globulin were significantly lower.

CONCLUSIONS

Sex-linked genes may account for the intrinsic sex difference observed. These genes may have an important impact on the development of insulin resistance and the metabolic syndrome and may help to explain the female preponderance of type 2 diabetes in children. Their identification may also help in understanding the pathogenesis of insulin resistance.

Obesity in American-Indian children: prevalence, consequences, and prevention

BACKGROUND

American Indians of all ages and both sexes have a high prevalence of obesity. The health risks associated with obesity are numerous and include Type 2 diabetes mellitus, hypertension, dyslipidemia, and respiratory problems. Obesity has become a major health problem in American Indians only in the past few generations and it is believed to be associated with the relative abundance of high-fat, high-calorie foods and the rapid change from active to sedentary lifestyles.

METHODS

The authors reviewed selected literature on prevalence of obesity in American-Indian children, and health consequences of obesity.

RESULTS

Obesity is now one of the most serious public health problems facing American-Indian children, and it has grave implications for the immediate and long-term health of American-Indian youth. Unless this pattern is reversed, American-Indian populations will be burdened by an increased incidence of chronic diseases. Intervention studies are urgently needed in American-Indian communities to develop and test effective strategies for obesity prevention and treatment.

CONCLUSIONS

To be effective, educational and environmental interventions must be developed with full participation of the American-Indian communities.

Plasma lipoprotein concentrations in ethnic populations

There is a complex interplay between genetic and environmental factors that influences the expression of plasma lipoprotein levels. It is therefore not surprising that differences in lipid levels have been reported between ethnic groups. There are conflicting data on racial and ethnic variations in lipids, and also limited data on the relationship between lipoprotein levels and coronary heart disease risk in specific populations. This review summarizes available data on ethnic variations in plasma lipoproteins and the potential impact on coronary morbidity and mortality.

Obesity correlates with increased blood pressures in urban Native American youth

Although obesity is a growing problem with Native American youth living on reservations, little research has been conducted examining the prevalence of obesity and correlations between age, body composition, dietary intake, and blood pressures (BP) for urban Native youth. The purpose of this study was to investigate the relationship of these variables in urban Native American youth. Height and weight were measured for 155 Native American youth, age 5-18 years, and the body mass index (BMI) was calculated and classified into percentile categories. Skinfold thicknesses at the biceps, triceps, suprailiac, and subscapular sites, arm and waist circumferences, and systolic (SBP) and diastolic (DBP) blood pressures were also measured. There was a high proportion of obesity (>95 percentile) for youth in all age groups. The prevalence was 38% for the 5-10-year-olds and 45% for the 11-18-year-olds youth. There were no significant correlations between SBP and DBP and dietary variables. Mean SBP and DBP increased with increasing BMI percentiles. Stepwise regression analyses showed that waist circumference, age, and BMI were strong predictors for SBP, while waist circumference and age were predictors for DBP in the total sample. The findings suggest that overweight/obesity is very prevalent among urban Native American youth and the increased adiposity is associated with increased SBP and DBP.

Evaluation of the safety and efficacy of sibutramine, orlistat and metformin in the treatment of obesity

AIM

Some of our obese patients who were receiving 10 mg/day sibutramine reported feeling hunger at night. To address this, we designed a randomized, prospective clinical trial to study the efficacy and safety of 10 mg sibutramine twice daily (bid), and compare this treatment with 120 mg orlistat three times daily (tid) and 850 mg metformin (bid).

METHODS

A total of 150 female patients with body mass index (b.m.i.) > 30 kg/m(2) were included. The subjects were all out-patients at the Başkent University Endocrinology and Metabolism Clinic. Each individual was assigned randomly to receive 10 mg sibutramine bid (group 1; n = 50; mean age 42.27 +/- 1.40 years), 120 mg orlistat tid (group 2; n = 50; mean age 42.13 +/- 1.32 years) or 850 mg metformin bid (group 3; n = 50; mean age 43.58 +/- 1.40 years). All patients took the medications for 6 months. Two patients from the sibutramine group and two from the orlistat group were withdrawn from the study because of side-effects.

RESULTS

After 6 months of treatment, the sibutramine, orlistat, and metformin groups all showed significantly reduced b.m.i. (13.57%, 9.06% and 9.90% respectively); waist circumference (10.43%, 6.64%, and 8.10% respectively); fasting and postprandial blood glucose levels; insulin resistance as assessed by the homeostasis model for assessment of insulin resistance (HOMA) (38.63%, 32.73% and 39.28%, respectively); levels of total cholesterol, low-density lipoprotein (LDLC) cholesterol, very low-density lipoprotein (VLDLC) cholesterol, triglyceride, lipoprotein (a), and apolipoprotein B; uric acid level; pulse rate; and systolic and diastolic blood pressure. None of the groups showed any significant changes in levels of high-density lipoprotein (HDLC) cholesterol, or apolipoprotein A1. There was a significantly greater fall in b.m.i. in the sibutramine group than in either of the other groups (p < 0.0001).

CONCLUSIONS

The results of this study confirm that sibutramine, orlistat and metformin are all effective and safe medications that reduce cardiovascular risk and can decrease the risk of type 2 diabetes mellitus in obese females. Overall, treatment with 10 mg sibutramine bid is more effective than orlistat or metformin therapy in terms of weight reduction.

Correlates and predictors of adiposity among Mohawk children

BACKGROUND

High rates of Type 2 diabetes in Native populations underlie the need for research on risk factors, including physical activity (PA) and obesity.

METHODS

In 1994 and in 1996, 103 girls and 95 boys [mean age (standard deviation): 7.5 (1.3) years] attending elementary schools in two Mohawk communities completed a questionnaire assessing demographic and lifestyle variables. In addition, height, weight, and subscapular skinfold thickness (SSF) were measured and children performed a run/walk fitness (R/W) test. Gender-specific multiple linear regression assessed the impact of baseline variables on the log of SSF at baseline and follow-up.

RESULTS

In cross-sectional analyses among boys and girls, the common correlates of baseline SSF included failing to achieve the minimal fitness standard for the R/W test and being involved in summer sports. Additional correlates identified only among girls included excessive television watching, lower PA, and involvement in community sports. Longitudinal predictors among girls were younger age, being from the comparison community, excessive TV, and PA. Among boys, only baseline SSF predicted follow-up SSF. Girls who watched excessive TV had SSFs 30 and 14% greater than those who watched less TV at baseline and follow-up, respectively.

CONCLUSION

TV viewing was the only consistent determinant of adiposity among girls.

Ethnic issues in the epidemiology of childhood obesity

Childhood obesity may be seen as a marker for high-risk dietary and physical inactivity practices. Recent increases in the prevalence of overweight and obesity among American children are not limited to one age, gender, or ethnic group, which suggests that unique behaviors of the members of various racial or ethnic subgroups of the population are unlikely to be the major contributing factors. Rather, it seems that environmental changes promoting increased energy intake and decreased energy output are occurring and have widespread impact on children from various backgrounds. Although no ethnic group is immune from the current shift in energy balance, differential rates of overweight seem to exist among ethnic groups. National probability samples of African-American, Hispanic, and white children in the United States provide clear evidence that white children are at lower risk for childhood overweight than are African-American or Hispanic children. Of concern is the lack of national data on the prevalence of overweight and obesity for Native-American and Asian-American groups. Also of concern is the aggregation of racial and ethnic subgroups, which may render prevalence rates meaningless. This possibility is clearly true with some surveys of weight status that combine diverse populations, such as Asians and Pacific Islanders, into one group. The high rates of obesity in African-American, Hispanic, and Native-American children are of concern. Although parental SES is associated inversely with childhood obesity among whites, higher SES does not seem to protect African-American and Hispanic children against obesity. In these groups, childhood obesity does not seem to be associated significantly with parental income and education. Health consequences of childhood obesity include a higher prevalence of type 2 diabetes and an increased risk for adverse levels of lipids, lipoproteins, and blood pressure. The effects of recently reported unprecedented levels of childhood overweight on subsequent risk for obesity in middle age are not known until future longitudinal data can be collected. It seems likely, however, that future health consequences of current early and severe childhood obesity will be staggering. Funding for adult follow-up of longitudinal studies of high-risk African American, Hispanic, and Native-American children is needed urgently to provide information on the long-term effects of childhood obesity. Halting the obesity epidemic is a formidable task, but the success in recent decades of drastically reducing childhood undernutrition offers hope and should spur similar action and leadership efforts. Promotion of efforts to reduce excess caloric intake with efforts to increase energy expenditure should receive paramount attention in the design of health programs. Given the relatively few published obesity-prevention and treatment studies that are designed to address specific cultural issues, it is important to promote the development of culturally appropriate intervention strategies that are shown to be effective among youth of diverse backgrounds. Although the dietary and activity goals will be similar, parental, family, and community messages and techniques grounded in cultural traditions and norms will be different for each ethnic group. This approach is crucial in the United States, a country with an increasingly diverse population.

Waist circumference and waist-to-height ratio are better predictors of cardiovascular disease risk factors in children than body mass index

BACKGROUND

Visceral adipose tissue is associated with increased risk for cardiovascular disease risk factors and morbidity from cardiovascular diseases. Waist measurement and waist-to-height ratio (WHtR) have been used as proxy measures of visceral adipose tissue, mainly in adults.

OBJECTIVE

To validate body mass index (BMI), waist circumference and WHtR as predictors for the presence of cardiovascular disease risk factors in children of Greek-Cypriot origin.

SUBJECTS AND METHODS

A total of 1,037 boys and 950 girls with mean age 11.4+/-0.4 y were evaluated. Dependent variables for the study were total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholestrol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and systolic (SBP) and diastolic (DBP) blood pressure.

RESULTS

When children were divided into two groups according to the 75th percentile for BMI, waist circumference and WHtR, all dependent variables had higher mean values in the highest percentile groups in WHtR groups and almost all variables in BMI and waist circumference groups. Adjusted odds ratios for predicting pathological values of cardiovascular disease risk factors were slightly higher for the highest WHtR group for predicting lipid and lipoprotein pathological values and for the highest BMI groups in predicting high blood pressure measurement. Using stepwise multiple regression analysis to explain the variance of the dependent variables, waist circumference was the most significant predictor for all variables both for boys and girls, whereas BMI had the lowest predictive value for the detection of cardiovascular disease risk factors.

CONCLUSION

Waist circumference and WHtR are better predictors of cardiovascular disease risk factors in children than BMI. Further studies are necessary to determine the cutoff points for these indices for an accurate prediction of risk factors.

Effects of obesity and body fat distribution on lipids and lipoproteins in nondiabetic American Indians: The Strong Heart Study

OBJECTIVES

To examine the relationship between obesity and lipoprotein profiles and compare the effects of total obesity and central adiposity on lipids/lipoproteins in American Indians.

RESEARCH METHODS AND PROCEDURES

Participants were 773 nondiabetic American Indian women and 739 men aged 45 to 74 years participating in the Strong Heart Study. Total obesity was estimated using body mass index (BMI). Central obesity was measured as waist circumference. Lipoprotein measures included triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein AI (apoAI), and apolipoprotein B (apoB). Partial and canonical correlation analyses were used to examine the associations between obesity and lipids/ lipoproteins.

RESULTS

Women were more obese than men in Arizona (median BMI 32.1 vs. 29.2 kg/m2) and South Dakota and North Dakota (28.3 vs. 28.0 kg/m2), but there was no sex difference in waist circumference. Men had higher apoB and lower apoAI levels than did women. In women, when adjusted for center, gender, and age, BMI was significantly related to HDL cholesterol (r = -0.24, p < 0.001). There was a significant but weak relation with apoAI (r = -0.14, p < 0.001). Waist circumference was positively related to triglycerides (r = 0.14, p < 0.001) and negatively related to HDL cholesterol (r = -0.23, p < 0.001) and apoAI (r = -0.13, p < 0.001). In men, BMI was positively correlated with triglycerides (r = 0.30, p < 0.001) and negatively correlated with HDL cholesterol (r = -0.35, p < 0.001) and apoAI (r = -0.23, p < 0.001). Triglycerides increased with waist circumference (r = 0.30, p < 0.001) and HDL cholesterol decreased with waist circumference (r = -0.36, p < 0.001). In both women and men there was an inverted U-shaped relationship between obesity and waist with LDL cholesterol and apoB. In canonical correlation analysis, waist circumference received a greater weight (0.86) than did BMI (0.17) in women. However, the canonical weights were similar for waist (0.46) and BMI (0.56) in men. Only HDL cholesterol (-1.02) carried greater weight in women, whereas in men, triglycerides (0.50), and HDL cholesterol (-0.64) carried a large amount of weight. All the correlation coefficients between BMI, waist circumference, and the first canonical variable of lipids/lipoproteins or between the individual lipid/lipoprotein variables and the first canonical variable of obesity were smaller in women than in men. Triglycerides and HDL cholesterol showed clinically meaningful changes with BMI and waist circumference in men. All lipid/lipoprotein changes in women in relation to BMI and waist circumference were minimal.

DISCUSSION

The main lipoprotein abnormality related to obesity in American Indians was decreased HDL cholesterol, especially in men. Central adiposity was more associated with abnormal lipid/lipoprotein profiles than general obesity in women; both were equally important in men.

Type 2 diabetes among North American children and adolescents: an epidemiologic review and a public health perspective

OBJECTIVES

To review the magnitude, characteristics, and public health importance of type 2 diabetes in North American youth.

RESULTS

Among 15- to 19-year-old North American Indians, prevalence of type 2 diabetes per 1000 was 50.9 for Pima Indians, 4.5 for all US American Indians, and 2.3 for Canadian Cree and Ojibway Indians in Manitoba. From 1967-1976 to 1987-1996, prevalence increased 6-fold for Pima Indian adolescents. Among African Americans and whites aged 10 to 19 years in Ohio, type 2 diabetes accounted for 33% of all cases of diabetes. Youth with type 2 diabetes were generally 10 to 19 years old, were obese and had a family history of type 2 diabetes, had acanthosis nigricans, belonged to minority populations, and were more likely to be girls than boys. At follow-up, glucose control was often poor, and diabetic complications could occur early.

CONCLUSIONS

Type 2 diabetes is an important problem among American Indian and First Nation youth. Other populations have not been well studied, but cases are now occurring in all population groups, especially in ethnic minorities. Type 2 diabetes among youth is an emerging public health problem, for which there is a great potential to improve primary and secondary prevention.

Growth and overweight of Navajo youth: secular changes from 1955 to 1997

OBJECTIVE

To examine the growth status, prevalence of risk of overweight and of overweight, and secular changes in growth status in Navajo youth from 1955 to 1997.

SUBJECTS

526 (256 males, 270 females) Navajo children 6-12 y of age.

MEASUREMENTS

Stature and mass were measured and the body mass index (BMI) was calculated.

ANALYSIS

All three variables were plotted relative to age- and sex-specific US reference data and the prevalence rates for risk of overweight and of overweight were estimated using the BMI as the criterion. The cut-off for the risk of overweight was the age- and sex-specific 85th and 95th percentiles of NHANES I, while the cut-off for overweight was a BMI>/=95th percentiles. Age-specific sex differences were compared using independent samples t-tests. Secular changes for body size were estimated by comparing age- and sex-specific means for stature, mass, and the BMI in the present study and two previous studies in 1955 and 1989.

RESULTS

No statistically significant differences were observed between sexes within age groups. In both sexes, mean age-specific stature appeared to be relatively stable around the 50th percentile of US reference values. Mean age-specific mass appeared to be relatively stable between the 50th and 90th percentiles of the reference values, while the mean BMI tended to fluctuate about the 85th percentile. Approximately 41% of the Navajo boys and girls 6-12 y of age had BMIs >/=85th percentiles of US reference data. Compared to corresponding data on Navajo youth in 1955 and 1989, the current sample was larger in mass and the BMI. The estimated rate of secular change in mass was about 1.5 kg/decade in younger boys and girls, and about 3 kg/decade in older boys and girls between 1955 and 1997. The estimated rate of secular change in the BMI was about 0.5-1.0 units/decade between 1955 and 1997, while that for stature was about 2 cm/decade between 1955 and 1997.

CONCLUSIONS

The results are consistent with recent findings on the Navajo Health and Nutrition Survey that overweight is a serious public health concern across the lifespan in the Navajo, and that the problem begins in childhood. Furthermore, Navajo children appear to be heavier than about a decade ago. International Journal of Obesity (2000) 24, 211-218

The epidemic of obesity in American Indian communities and the need for childhood obesity-prevention programs

American Indians of all ages and both sexes have a high prevalence of obesity. The high prevalence of diabetes mellitus in American Indians shows the adverse effects that obesity has in these communities. Obesity has become a major health problem in American Indians only in the past 1-2 generations and is believed to be associated with the relative abundance of high-fat foods and the rapid change from active to sedentary lifestyles. Intervention studies are urgently needed in American Indian communities to develop and test effective strategies for weight reduction. The poor success rate of adult obesity treatment programs in the general population points to the need to develop prevention approaches aimed toward children. Because eating and physical activity practices are formed early in life and may be carried into adulthood, prevention programs that encourage increased physical activity and healthful eating habits targeted toward young people need to be developed and tested. To be most effective, interventions must be developed with full participation of the American Indian communities.

Risk factors for coronary heart disease among Navajo Indians: findings from the Navajo Health and Nutrition Survey

Coronary heart disease was uncommon among the Navajo in the past, but appears to have increased substantially over the last few decades. The 1991-1992 Navajo Health and Nutrition Survey, which included interviews and examinations of 303 men and 485 women between the ages of 20 and 91 y, is the first population-based examination of coronary heart disease risk factors in this tribe. Coronary heart disease risk characteristics were common, particularly overweight (men, 35%; women, 62%), hypertension (men, 23%; women, 14%) and diabetes mellitus (men, 17%; women, 25%). Among 20- to 39-y-olds, a large proportion of men reported that they currently smoked cigarettes (23%); use of chewing tobacco or snuff was also prevalent among these 20- to 39-y-old men (37%) and women (31%). Although serum concentrations of total cholesterol were fairly comparable to those seen in the general U.S. population, fasting serum triglyceride concentrations were high (median: men, 132 mg/dL; women, 137 mg/dL), and concentrations of HDL cholesterol were low, particularly among women (median: men, 42 mg/dL; women, 44 mg/dL). Body mass index was associated with levels of most risk factors, and, independently of the level of overweight, a truncal pattern of body fat was related to adverse lipid levels among men. A large proportion of men (20%) and women (30%) reported not having participated in physical activity during the preceding month. Lessons learned from past intervention activities among the Navajo, particularly those for diabetes, may be useful in managing these risk factors to reduce the future burden of coronary heart disease.

Weight, body image, and weight control practices of Navajo Indians: findings from the Navajo Health and Nutrition Survey

Historically, the Navajo exhibited a low prevalence of overweight, but a number of small studies over the past few decades indicate that the prevalence is increasing. In the population-based Navajo Health and Nutrition Survey conducted in 1991-92, overweight was defined as a body mass index (BMI, kg/m2) at or above the 85th percentile (BMI > 27.8 for men, > 27.3 for women) of the Second National Health and Nutrition Examination Survey. One third of men age 20 and 39 and one half of men age 40 and 59, but fewer than 10% of men age 60 and older were overweight. Two thirds or more of women in all age groups were overweight. Nineteen percent of the participants underestimated their weight status (underweight, appropriate, overweight) relative to their BMI category and 17% overestimated their weight status. Women overestimated their weight status more often than men (P < 0.05), and participants age 20-39 overestimated their weight status more often than older participants (P < 0.001). Men and women age 60 and older preferred heavier body shape models as ideals of health more often than younger participants (P < 0.001). Nearly half of the participants, regardless of their weight status, reported that they were trying to lose weight; most reported using diet and exercise. Because overweight is an important risk factor for many chronic diseases, including diabetes mellitus, cardiovascular disease and cancer, primary prevention of overweight and weight management for adults are recommended to prevent an increase in the burden of chronic disease among the Navajo.