Diet quality and its association with type 2 diabetes and major cardiometabolic risk factors among adults in China

AIM

We examined the association between diet quality and diabetes and major cardiometabolic risks among adults in China.

METHODS AND RESULTS

We developed the China Dietary Guideline Index (CDGI) based on the 2007 Chinese dietary guidelines and tailored the Alternate Healthy Eating Index 2010 (which we call the tAHEI) to assess diet quality. Our analysis linked the dietary intake and covariates measured in 2006 with CM risk factors measured in 2009. We used diet data the longitudinal China Health and Nutrition Survey 2006 collected in 3 consecutive 24-h recalls from 4440 adults aged 18 to 65 to calculate both the tAHEI and the CDGI scores. We performed multivariable logistic regressions to analyze the association of each 2006 score with diabetes, abdominal obesity, elevated blood pressure, and lipid-related cardiometabolic risk factors in 2009. After we adjusted for potential confounders, adults in the top quintile compared with the bottom quintile of the tAHEI scores showed 36% lower odds of high low-density lipoprotein cholesterol (LDL-C) (odds ratio [OR] 0.64; 95% confidence interval [CI] 0.46, 0.90] in men and 33% lower odds (OR 0.67; 95% CI 0.49, 0.91) in women, while the CDGI scores showed 35% lower odds of high LDL-C (OR 0.65; 95% CI 0.46, 0.92) in men only. Further, the CDGI scores indicated 55% lower odds of diabetes in the top versus the bottom quintile (OR 0.45; 95% CI 0.23, 0.87) in men only, whereas a null association was observed for the tAHEI scores for both sexes. Both index scores showed null associations with other cardiometabolic risk factors.

CONCLUSIONS

Chinese diets that scored high on both the CDGI and the tAHEI showed similarly negative associations with high LDL-C risk, whereas only CDGI score was negatively related to diabetes risk in men.

BMI loci and longitudinal BMI from adolescence to young adulthood in an ethnically diverse cohort

Objective

The association of obesity susceptibility variants with change in body mass index (BMI) across the life course is not well understood.

Subjects

In ancestry stratified models of 5,962 European American (EA), 2,080 African American (AA), and 1,582 Hispanic American (HA) individuals from the National Longitudinal Study of Adolescent to Adult Health (Add Health), we examined associations between 34 obesity SNPs with per year change in BMI, measured by the slope from a growth-curve analysis of two or more BMI measurements between adolescence and young adulthood. For SNPs nominally associated with BMI change (p<0.05), we interrogated age differences within data collection Wave and time differences between age categories that overlapped between Waves.

Results

We found SNPs in/near FTO, MC4R, MTCH2, TFAP2B, SEC16B, and TMEM18 were significantly associated (p<0.0015 ≈ 0.05/34) with BMI change in EA and the ancestry-combined meta-analysis. Rs9939609 in FTO met genome-wide significance at p<5e-08 in the EA and ancestry combined analysis, respectively [Beta(se)=0.025(0.004);Beta(se)=0.021(0.003)]. No SNPs were significant after Bonferroni correction in AA or HA, although 5 SNPs in AA and 4 SNPs in HA were nominally significant (p<0.05). In EA and the ancestry-combined meta-analysis, rs3817334 near MTCH2 showed larger effects in younger respondents, while rs987237 near TFAP2B, showed larger effects in older respondents across all Waves. Differences in effect estimates across time for MTCH2 and TFAP2B are suggestive of either era or cohort effects.

Conclusion

The observed association between variants in/near FTO, MC4R, MTCH2, TFAP2B, SEC16B, and TMEM18 with change in BMI from adolescence to young adulthood suggest that the genetic effect of BMI loci varies over time in a complex manner, highlighting the importance of investigating loci influencing obesity risk across the life course.

The interaction between physical activity and obesity gene variants in association with BMI: Does the obesogenic environment matter?

Little is known about how obesity susceptibility single nucleotide polymorphisms (SNPs) interact with moderate to vigorous physical activity (MVPA) in relation to BMI during adolescence, once obesogenic neighborhood factors are accounted for. In race stratified models, including European (EA; N=4977), African (AA; N=1726), and Hispanic Americans (HA; N=1270) from the National Longitudinal Study of Adolescent to Adult Health (1996; ages 12-21), we assessed the evidence for a SNPxMVPA interaction with BMI-for-age Z score, once accounting for obesogenic neighborhood factors including physical activity amenities, transportation and recreation infrastructure, poverty and crime. Eight SNPxMVPA interactions with suggestive significance (p<0.10; three in each EA, and AA, two in HA) were observed showing attenuation on BMI-for-age Z score in adolescents with ≥5 versus <5 bouts/week MVPA, except for rs10146997 (near NRXN3). Findings were robust to the inclusion of neighborhood-level variables as covariates. These findings suggest that any attenuation from MVPA on a genetic susceptibility to obesity during adolescence is likely not operating through obesogenic neighborhood factors.

Influence of SNP*SNP interaction on BMI in European American adolescents: findings from the National Longitudinal Study of Adolescent Health

BACKGROUND

Adolescent obesity is predictive of future weight gain, obesity and adult onset severe obesity (body mass index [BMI] ≥40 kg m(-2) ). Despite successful efforts to identify Single Nucleotide Polymorphisms (SNPs) influencing BMI, <5% of the 40-80% heritability of the phenotype has been explained. Identification of gene-gene (G-G) interactions between known variants can help explain this hidden heritability as well as identify potential biological mechanisms affecting weight gain during this critical developmental period.

OBJECTIVE

We have recently shown distinct genetic effects on BMI across the life course, and thus it is important to examine the evidence for epistasis in adolescence.

METHODS

In adolescent participants of European descent from wave II of the National Longitudinal Study of Adolescent Health (Add Health, n = 5072, ages 12-21, 52.5% female), we tested 34 established BMI-related SNPs for G-G interaction effects on BMI z-score. We used mixed-effects regression, assuming multiplicative interaction models adjusting for age, sex and geographic region, with random effects for family and school.

RESULTS

For 28 G-G interactions that were nominally significant (P < 0.05), we attempted to replicate our results in an adolescent sample from the Childhood European American Cohort from Philadelphia. In the replication study, one interaction (PRKD1-FTO) was significant after correction for multiple testing.

CONCLUSIONS

Our results are suggestive of epistatic effects on BMI during adolescence and point to potentially interactive effects between genes in biological pathways important in obesity.

Implications of iron deficiency/anemia on the classification of diabetes using HbA1c

Background/Objectives:

Nonglycemic factors like iron deficiency (ID) or anemia may interfere with classification of diabetes and prediabetes using hemoglobin A1c (HbA1c). However, few population-based studies of diabetes in areas with endemic ID/anemia have been conducted. We aimed to determine how mutually exclusive categories of ID alone, anemia alone and iron-deficiency anemia (IDA) were each associated with prediabetes and diabetes prevalence using fasting blood glucose (FBG) versus HbA1c in a population-based study of adults with endemic ID/anemia.

Subjects/Methods:

We used data from the China Health and Nutrition Survey, a longitudinal, population-based study across 228 communities within nine provinces of China. This analysis included 7308 adults seen in the 2009 survey aged 18–75 years. We used descriptive and covariate-adjusted models to examine relative risk of prediabetes and diabetes using FBG alone, HbA1c alone, HbA1c and FBG, or neither (normoglycemia) by anemia alone, ID alone, IDA or normal iron/hemoglobin.

Results:

Approximately 65% of individuals with diabetes in our sample were concordantly classified with diabetes using both FBG and HbA1c, while 35% had a discordant diabetes classification: they were classified using either FBG or HbA1c, but not both. Fewer participants with ID alone versus normal iron/hemoglobin were classified with diabetes using HbA1c only. From covariate-adjusted, multinomial regression analyses, the adjusted prevalence of prediabetes using HbA1c only was 22% for men with anemia alone, but 13% for men with normal iron/hemoglobin. In contrast, the predicted prevalence of prediabetes using HbA1c only was 8% for women with ID alone, compared with 13% for women with normal iron/hemoglobin.

Conclusions:

These findings suggest potential misclassification of diabetes using HbA1c in areas of endemic ID/anemia. Estimating diabetes prevalence using HbA1c may result in under-diagnosis in women with ID and over-diagnosis in men with anemia.

The association between childhood sexual and physical abuse with incident adult severe obesity across 13 years of the National Longitudinal Study of Adolescent Health

BACKGROUND

Severe obesity has increased, yet childhood antecedents of adult severe obesity are not well understood.

OBJECTIVE

Estimate adult-onset severe obesity risk in individuals with history of childhood physical and/or sexual abuse compared with those who did not report abuse.

METHODS

Longitudinal analysis of participants from the US National Longitudinal Study of Adolescent Health (n = 10,774) wave II (1996; aged 12-22 years) followed through wave IV (2008-2009; aged 24-34 years). New cases of adult-onset severe obesity (body mass index [BMI] ≥ 40 kg/m2 using measured height and weight) in individuals followed over 13 years who were not severely obese during adolescence (BMI <120% of 95th percentile Centers for Disease Control and Prevention National Center for Health Statistics growth curves).

RESULTS

The combined occurrence of self-reported sexual and physical abuse during childhood was associated with an increased risk of incident severe obesity in adulthood in non-minority females (hazard ratio [HR; 95% Confidence Interval] = 2.5; 1.3, 4.8) and males (HR = 3.6; 1.5, 8.5) compared with individuals with no history of abuse.

CONCLUSION

In addition to other social and emotional risks, exposure to sexual and physical abuse during childhood may increase risk of severe obesity later in life. Consideration of the confluence of childhood abuse might be considered as part of preventive and therapeutic approaches to address severe obesity.

Moderate to vigorous physical activity interactions with genetic variants and body mass index in a large US ethnically diverse cohort

BACKGROUND

Little is known about the interaction between genetic and behavioural factors during lifecycle risk periods for obesity and how associations vary across race/ethnicity.

OBJECTIVE

The objective of this study was to examine joint associations of adiposity-related single-nucleotide polymorphisms (SNPs) and moderate to vigorous physical activity (MVPA) with body mass index (BMI) in a diverse adolescent cohort.

METHODS

Using data from the National Longitudinal Study of Adolescent Health (n = 8113: Wave II 1996; ages 12-21, Wave III; ages 18-27), we assessed interactions of 41 well-established SNPs and MVPA with BMI-for-age Z-scores in European Americans (EA; n = 5077), African-Americans (AA; n = 1736) and Hispanic Americans (HA; n = 1300).

RESULTS

Of 97 assessed, we found nominally significant SNP-MVPA interactions on BMI-for-age Z-score in EA at GNPDA2 and FTO and in HA at LZTR2/SEC16B. In EA, the estimated effect of the FTO risk allele on BMI-for-age Z-score was lower (β = -0.13; 95% confidence interval [CI]: 0.08, 0.18) in individuals with ≥5 vs. <5 (β = 0.24; CI: 0.16, 0.32) bouts of MVPA per week (P for interaction 0.02). Race/ethnicity-pooled meta-analysis showed nominally significant interactions for SNPs at TFAP2B, POC5 and LYPLAL1.

CONCLUSIONS

High MVPA may attenuate underlying genetic risk for obesity during adolescence, a high-risk period for adult obesity.

Screen time behaviours may interact with obesity genes, independent of physical activity, to influence adolescent BMI in an ethnically diverse cohort

BACKGROUND

There has been little investigation of gene-by-environment interactions related to sedentary behaviour, a risk factor for obesity defined as leisure screen time (ST; i.e. television, video and computer games).

OBJECTIVE

To test the hypothesis that limiting ST use attenuates the genetic predisposition to increased body mass index (BMI), independent of physical activity.

DESIGN

Using 7642 wave II participants of the National Longitudinal Study of Adolescent Health, (Add Health; mean = 16.4 years, 52.6% female), we assessed the interaction of ST (h week(-1) ) and 41 established obesity single nucleotide polymorphisms (SNPs) with age- and sex-specific BMI Z-scores in 4788 European-American (EA), 1612 African-American (AA) and 1242 Hispanic American (HA) adolescents.

RESULTS

Nominally significant SNP*ST interaction were found for FLJ35779 in EA, GNPDA2 in AA and none in HA (EA: beta [SE] = 0.016[0.007]), AA: beta [SE] = 0.016[0.011]) per 7 h week(-1) ST and one risk allele in relation to BMI Z-score.

CONCLUSIONS

While for two established BMI loci, we find evidence that high levels of ST exacerbate the influence of obesity susceptibility variants on body mass; overall, we do not find strong evidence for interactions between the majority of established obesity loci. However, future studies with larger sample sizes, or that may build on our current study and the growing published literature, are clearly warranted.

The spatial distribution of overweight and obesity among a birth cohort of young adult Filipinos (Cebu Philippines, 2005): an application of the Kulldorff spatial scan statistic

OBJECTIVES

The objectives of the study were to test for spatial clustering of obesity in a cohort of young adults in the Philippines, to estimate the locations of any clusters, and to relate these to neighborhood-level urbanicity and individual-level socioeconomic status (SES).

SUBJECTS

Data are from a birth cohort of young adult (mean age 22 years) Filipino males (n=988) and females (n=820) enrolled in the Cebu Longitudinal Health and Nutrition Survey.

METHODS

We used the Kulldorff spatial scan statistic to detect clusters associated with unusually low or high prevalences of overweight or obesity (defined using body mass index, waist circumference and body fat percentage). Cluster locations were compared to neighborhood-level urbanicity, which was measured with a previously validated scale. Individual-level SES was adjusted for using a principal components analysis of household assets.

RESULTS

High-prevalence clusters were typically centered in urban areas, but often extended into peri-urban and even rural areas. There were also differences in clustering by both sex and the measure of obesity used. Evidence of clustering in males, but not females, was much weaker after adjustment for SES.

PNPLA3 gene-by-visceral adipose tissue volume interaction and the pathogenesis of fatty liver disease: the NHLBI family heart study

BACKGROUND

Fatty liver disease (FLD) is characterized by increased intrahepatic triglyceride content with or without inflammation and is associated with obesity, and features of the metabolic syndrome. Several recent genome-wide association studies have reported an association between single-nucleotide polymorphism rs738409 in the (patatin-like phospholipase domain-containing protein 3) PNPLA3 gene and FLD. Liver attenuation (LA; hounsfield units, HU) by computed tomography is a non-invasive measure of liver fat, with lower values of HU indicating higher liver fat content. Clinically, a LA value of 40 HU indicates moderate-to-severe hepatic steatosis.

OBJECTIVE

We investigated whether missense rs738409 PNPLA3 interacted with abdominal visceral adipose tissue (VAT) volume (cm) to reduce LA (that is, increased liver fat) in 1019 European American men and 1238 European American women from the Family Heart Study.

METHODS

We used linear regression to test the additive effect of genotype, abdominal VAT, and their multiplicative interaction on LA adjusted for age, body mass index, high-density lipoprotein-cholesterol, insulin resistance, serum triglycerides, abdominal subcutaneous adipose tissue and alcohol intake.

RESULTS

In men and women combined, the interaction between each copy of the rs738409 variant allele (minor allele frequency 0.23) and 100 cm/150 mm slice VAT decreased LA by 2.68±0.35 HU (P<0.01). The interaction of 100 cm VAT and the variant allele was associated with a greater decrease in LA in women than men (-4.8±0.6 and -2.2±0.5 HU, respectively).

CONCLUSIONS

The interaction between genotype and VAT volume suggest key differences in the role of PNPLA3 genotype in conjunction with abdominal VAT in liver fat accrual. The stronger association of the PNPLA3 genotype and liver fat in women suggests that women may be more sensitive to liver fat accumulation in the setting of increased visceral fat, compared with men. The presence of the PNPLA3 variant genotype, particularly in the context of high VAT content may have an important role in FLD.

Multilevel examination of diabetes in modernising China: what elements of urbanisation are most associated with diabetes?

AIMS/HYPOTHESIS

The purpose of this study was to examine the association between urbanisation-related factors and diabetes prevalence in China.

METHODS

Anthropometry, fasting blood glucose (FBG) and community-level data were collected for 7,741 adults (18-90 years) across 217 communities and nine provinces in the 2009 China Health and Nutrition Survey to examine diabetes (FBG ≥7.0 mmol/l or doctor diagnosis). Sex-stratified multilevel models, clustered at the community and province levels and controlling for individual-level age and household income were used to examine the association between diabetes and: (1) a multicomponent urbanisation measure reflecting overall modernisation and (2) 12 separate components of urbanisation (e.g., population density, employment, markets, infrastructure and social factors).

RESULTS

Prevalent diabetes was higher in more-urbanised (men 12%; women 9%) vs less-urbanised (men 6%; women 5%) areas. In sex-stratified multilevel models adjusting for residential community and province, age and household income, there was a twofold higher diabetes prevalence in urban vs rural areas (men OR 2.02, 95% CI 1.47, 2.78; women, OR 1.94, 95% CI 1.35, 2.79). All urbanisation components were positively associated with diabetes, with variation across components (e.g. men, economic and income diversity, OR 1.42, 95% CI 1.20, 1.66; women, transportation infrastructure, OR 1.18, 95% CI 1.06, 1.32). Community-level variation in diabetes was comparatively greater for women (intraclass correlation [ICC] 0.03-0.05) vs men (ICC ≤0.01); province-level variation was greater for men (men 0.03-0.04; women 0.02).

CONCLUSIONS/INTERPRETATION

Diabetes prevention and treatment efforts are needed particularly in urbanised areas of China. Community economic factors, modern markets, communications and transportation infrastructure might present opportunities for such efforts.

Estimation of genetic effects on BMI during adolescence in an ethnically diverse cohort: The National Longitudinal Study of Adolescent Health

OBJECTIVE

The contribution of genetic variants to body mass index (BMI) during adolescence across multiethnic samples is largely unknown. We selected genetic loci associated with BMI or obesity in European-descent samples and examined them in a multiethnic adolescent sample.

DESIGN AND SAMPLE

In 5103 European American (EA), 1748 African American (AfA), 1304 Hispanic American (HA) and 439 Asian American (AsA) participants of the National Longitudinal Study of Adolescent Health (Add Health; ages 12-21 years, 47.5% male), we assessed the association between 41 established obesity-related single-nucleotide polymorphisms (SNPs) with BMI using additive genetic models, stratified by race/ethnicity, and in a pooled meta-analysis sample. We also compared the magnitude of effect for BMI-SNP associations in EA and AfA adolescents to comparable effect estimates from 11 861 EA and AfA adults in the Atherosclerosis Risk in Communities study (ages 45-64 years, 43.2% male).

RESULTS

Thirty-five of 41 BMI-SNP associations were directionally consistent with published studies in European populations, 18 achieved nominal significance (P<0.05; effect sizes from 0.19 to 0.71 kg m(-2) increase in BMI per effect allele), while 4 (FTO, TMEM18, TFAP2B, MC4R) remained significant after Bonferroni correction (P<0.0015). Of 41 BMI-SNP associations in AfA, HA and AsA adolescents, nine, three and five, respectively, were directionally consistent and nominally significant. In the pooled meta-analysis, 36 of 41 effect estimates were directionally consistent and 21 of 36 were nominally significant. In EA adolescents, BMI effect estimates were larger (P<0.05) for variants near TMEM18, PTER and MC4R and smaller for variants near MTIF3 and NRXN3 compared with EA adults.

CONCLUSION

Our findings suggest that obesity susceptibility loci may have a comparatively stronger role during adolescence than during adulthood, with variation across race/ethnic subpopulation.

The expanding burden of cardiometabolic risk in China: the China Health and Nutrition Survey

China faces a major increase in cardiovascular disease, yet there is limited population-based data on risk factors, particularly in children. Fasting blood samples, anthropometry and blood pressure were collected on 9,244 children and adults aged ≥7 years in late 2009 as part of the national China Health and Nutrition Survey. Prevalent overweight, elevated blood pressure, and cardiometabolic risk factors: glucose, HbA1c, triglycerides (TG), total cholesterol (TC), high- and low-density lipoprotein cholesterol (HDL-C and LDL-C), and C-reactive protein (CRP) are presented. We found that 11% of Chinese children and 30% of Chinese adults are overweight. Rates of diabetes, dyslipidaemia, hypertension and inflammation are high and increased with age and were associated with urbanization. Approximately 42% of children have at least one of the following: pre-diabetes or diabetes, hypertension, high TC, LDL-C, TG, and CRP and low HDL-C, as do 70% men and 60% women aged 18-40 years and >90% of men and women ≥60 years. In sum, the HbA1c findings suggest that as many as 27.7 million Chinese children and 334 million Chinese adults may be pre-diabetic or diabetic. The high prevalence in less urban areas and across all income levels suggests that cardiometabolic risk is pervasive across rural and urban China.

The combined influence of genetic factors and sedentary activity on body mass changes from adolescence to young adulthood: the National Longitudinal Adolescent Health Study

BACKGROUND

an increase in sedentary activities is likely a major contributor to the rise in obesity over the last three decades. Little research has examined interactions between genetic variants and sedentary activity on obesity phenotypes. High levels of sedentary activity during adolescence may interact with genetic factors to influence body mass changes between adolescence and young adulthood, a high risk period for weight gain.

METHODS

in the National Longitudinal Study of Adolescent Health, siblings and twin pairs (16.5 ± 1.7 years) were followed into young adulthood (22.4 ± 1.8 years). Self-reported screen time (TV, video, and computer use in h/week) and body mass index (kg/m(2) ), calculated from measured height and weight at adolescence and at young adulthood, were available for 3795 participants. We employed a variance component approach to estimate the interaction between genotype and screen time for body mass changes. Additive genotype-by-screen time interactions were assessed using likelihood-ratio tests. Models were adjusted for race, age, sex, and age-by-sex interaction.

RESULTS

the genetic variation in body mass changes was significantly larger in individuals with low ( δ(G) = 27.59 ± 1.58) compared with high (δ(G) = 18.76 ± 2.59) levels of screen time (p < 0.003) during adolescence.

CONCLUSIONS

Our findings demonstrate that sedentary activities during adolescence may interact with genetic factors to influence body mass changes between adolescence and young adulthood. Accounting for obesity-related behaviours may improve current understanding of the genetic variation in body mass changes.

Walking for prevention of cardiovascular disease in men and women: a systematic review of observational studies

In this systematic review, walking (a generally accessible activity for a largely sedentary population) was assessed as a preventive risk factor for development of fatal and non-fatal cardiovascular disease (CVD). PubMed, CINHAL and reference list searches identified 21 peer-reviewed publications examining walking in relation to CVD; studies assessing active transportation were excluded. Generally, there were dose-dependent reductions in CVD risk with higher walking duration, distance, energy expenditure and pace. Associations appeared to be stronger for ischaemic stroke than other CVD outcomes such as coronary heart disease or haemorrhagic stroke. Adjustment for clinical CVD risk factors, obesity or other types of physical activity generally attenuated but did not eliminate associations. Because functional status may be an important determinant of walking behaviour in adults, potential bias due to pre-existing illness is of concern in all studies reviewed, particularly in case-control studies which ascertain walking retrospectively and yielded the strongest associations. Study findings were consistent with current physical activity recommendations, but there is a need for improvements in measurement of walking and other CVD risk factors, more thorough control for pre-existing illness, examination of mediating or moderating conditions such as obesity and other analytical issues.

Obesity, race/ethnicity and life course socioeconomic status across the transition from adolescence to adulthood

BACKGROUND

Differences in the association of socioeconomic status (SES) with obesity may underlie the racial/ethnic disparities in obesity that increase dramatically across the transition to adulthood in the United States. The aim of this study was to examine racial/ethnic differences in the influence of life course SES on longitudinal obesity patterns from adolescence to adulthood.

METHODS

Latent class analysis was used on a nationally representative, diverse sample of 12 940 adolescents followed into young adulthood (mean age = 21.7 years) to identify life course SES group profiles based on SES data in adolescence and young adulthood. Gender-stratified multinomial logistic regression models estimated the association of SES groups with obesity incidence and persistence versus staying non-obese.

RESULTS

No significant interactions with race/ethnicity were observed, although racial/ethnic minorities had the highest obesity risk across SES groups. Racial/ethnic-pooled associations between disadvantaged SES exposure and higher obesity risk were strong but differed by gender. Males with a disadvantaged background who experienced early transitions into the labour force, marriage and residential independence had the highest risk of obesity incidence (relative risk ratio (RRR) = 1.64; 95% confidence interval (CI) 1.12 to 2.40), while females exposed to persistent adversity were at highest risk (RRR = 3.01, 95% CI 1.95 to 4.66). In general, SES group membership had a stronger relationship with obesity persistence than incidence.

CONCLUSIONS

The relationship between SES and obesity patterns is similar across race/ethnicity and differs by gender during the transition to adulthood. However, stronger associations with obesity persistence and enduring racial/ethnic disparities in obesity risk across SES groups suggest that these social factors play a larger role in disparities earlier in the life course.

The nutrition transition: worldwide obesity dynamics and their determinants

OBJECTIVE

This paper explores the major changes in diet and physical activity patterns around the world and focuses on shifts in obesity.

DESIGN

Review of results focusing on large-scale surveys and nationally representative studies of diet, activity, and obesity among adults and children.

SUBJECTS

Youth and adults from a range of countries around the world.

MEASUREMENTS

The International Obesity Task Force guidelines for defining overweight and obesity are used for youth and the body mass index > or =25 kg/m(2) and 30 cutoffs are used, respectively, for adults.

RESULTS

The nutrition transition patterns are examined from the time period termed the receding famine pattern to one dominated by nutrition-related noncommunicable diseases (NR-NCDs). The speed of dietary and activity pattern shifts is great, particularly in the developing world, resulting in major shifts in obesity on a worldwide basis. Data limitations force us to examine data on obesity trends in adults to provide a broader sense of changes in obesity over time, and then to examine the relatively fewer studies on youth. Specifically, this work provides a sense of change both in the United States, Europe, and the lower- and middle-income countries of Asia, Africa, the Middle East, and Latin America.

CONCLUSION

The paper shows that changes are occurring at great speed and at earlier stages of the economic and social development of each country. The burden of obesity is shifting towards the poor.

Maturational timing and overweight prevalence in US adolescent girls

OBJECTIVES

This study examined the relation of age at menarche to overweight in US adolescent girls.

METHODS

Effects of age at menarche and race/ethnicity on overweight were estimated via logistic regression, after adjustment for sociodemographic characteristics, in a sample of 6507 Hispanic, Black, White, and Asian American girls who participated in wave 2 of the National Longitudinal Study of Adolescent Health.

RESULTS

Overweight prevalence rates were significantly higher in early maturing adolescents of all racial/ethnic groups but highest (57.5%) among early maturing Black girls. Early maturation nearly doubled the odds of being overweight (body mass index at or above the 85th percentile).

CONCLUSIONS

Greater public health attention should be focused on the high prevalence of overweight, particularly among minority female adolescents.

Obesity-related knowledge, attitudes, and behaviors in obese and non-obese urban Philadelphia female adolescents

OBJECTIVES

To examine relationships between knowledge, attitudinal and behavioral factors, and obesity and to determine how these factors influence obesity status in west Philadelphia female adolescents.

RESEARCH METHODS AND PROCEDURES

A matched-pairs study was conducted with 32 stature- and age-matched pairs of obese (body mass index and triceps skinfold > or =95th percentile of National Health and Nutrition Examination Survey I) and non-obese (body mass index and triceps skinfold between the 15th and 85th percentiles of National Health and Nutrition Examination Survey I) female African American adolescents (aged 11 to 15 years), selected from a school-based study sample, based on obesity status and matching criteria. Adolescents were compared on the following measures: physical activity, inactivity, dietary intake, eating attitudes, health behavior knowledge, body image, self-esteem, and maturation status. Differences between obese and non-obese females were tested using paired t tests and Wilcoxon matched-pairs signed-rank tests.

RESULTS

Physical activity, inactivity, and perception of ideal body size emerged as the most important contributory factors to obesity status. There were no statistically significant matched-pair differences in macronutrient and micronutrient intakes, self-esteem, eating attitudes, health behavior knowledge, or maturation status of these adolescents. Obese adolescents had significantly lower levels of physical activity, higher inactivity, and a larger perception of ideal body size than non-obese adolescents.

DISCUSSION

Knowledge and attitudinal factors (with the exception of perception of ideal body size) had far less association with obesity than activity-related behavioral factors. These findings suggest that future intervention strategies should pay particular attention to physical activity, inactivity, and body image attitudes.

Determinants of adolescent physical activity and inactivity patterns

OBJECTIVES

Despite recognition of the important influence of environmental determinants on physical activity patterns, minimal empirical research has been done to assess the impact of environmental/contextual determinants of physical activity. This article aims to investigate environmental and sociodemographic determinants of physical activity and inactivity patterns among subpopulations of US adolescents. We define environmental determinants as modifiable factors in the physical environment that impose a direct influence on the opportunity to engage in physical activity. The present research examines environmental and sociodemographic determinants of physical activity and inactivity with the implication that these findings can point toward societal-level intervention strategies for increasing physical activity and decreasing inactivity among adolescents.

STUDY DESIGN AND METHODOLOGY

The study population consists of nationally representative data from the 1996 National Longitudinal Study of Adolescent Health on 17 766 US adolescents enrolled in US middle and high schools (including 3933 non-Hispanic blacks, 3148 Hispanics, and 1337 Asians). Hours/week of inactivity (TV/video viewing and video/computer games) and times/week of moderate to vigorous physical activity were collected by questionnaire. Outcome variables were moderate to vigorous physical activity and inactivity, which were broken into categories (physical activity: 0-2 times/week, 3-4 times/week, and >/=5 times/week; inactivity: 0-10 hours/week, 11-24 hours/week, and >/=25 hours/week). Sociodemographic and environmental correlates of physical activity and inactivity were used as exposure and control variables and included sex, age, urban residence, participation in school physical education program, use of community recreation center, total reported incidents of serious crime in neighborhood, socioeconomic status, ethnicity, generation of residence in the United States, presence of mother/father in household, pregnancy status, work status, in-school status, region, and month of interview. Logistic regression models of high versus low and medium physical activity and inactivity were used to investigate sex and ethnic interactions in relation to environmental and sociodemographic factors to examine evidence for the potential impact of physical education and recreation programs and sociodemographic factors on physical activity and inactivity patterns.

RESULTS

Moderate to vigorous physical activity was lower and inactivity higher for non-Hispanic black and Hispanic adolescents. Participation in school physical education programs was considerably low for these adolescents and decreased with age. Participation in daily school physical education (PE) program classes (adjusted odds ratio [AOR]: 2.21; confidence interval [CI]: 1.82-2.68) and use of a community recreation center (AOR: 1.75; CI: 1.56-1.96) were associated with an increased likelihood of engaging in high level moderate to vigorous physical activity. Maternal education was inversely associated with high inactivity patterns; for example, having a mother with a graduate or professional degree was associated with an AOR of.61 (CI:.48-.76) for high inactivity. High family income was associated with increased moderate to vigorous physical activity (AOR: 1.43; CI: 1.22-1.67) and decreased inactivity (AOR:.70; CI:.59-.82). High neighborhood serious crime level was associated with a decreased likelihood of falling in the highest category of moderate to vigorous physical activity (AOR:.77; CI:.66-.91).

CONCLUSIONS

These results show important associations between modifiable environmental factors, such as participation in school PE and community recreation programs, with activity patterns of adolescents. Despite the marked and significant impact of participation in school PE programs on physical activity patterns of US adolescents, few adolescents participated in such school PE programs; only 21.3% of all adolescents

Adolescent physical activity and inactivity vary by ethnicity: The National Longitudinal Study of Adolescent Health

OBJECTIVES

To determine the extent to which physical activity and inactivity patterns vary by ethnicity among subpopulations of US adolescents.

STUDY DESIGN

Nationally representative data from the 1996 National Longitudinal Study of Adolescent Health of >14,000 US adolescents (including 3135 non-Hispanic blacks, 2446 Hispanics, and 976 Asians).

METHODS

Hours per week of inactivity (TV viewing, playing video or computer games) and times per week of moderate to vigorous physical activity were collected by using questionnaire data. Multinomial logistic regression models of physical activity and inactivity were used to adjust for sociodemographic factors.

RESULTS

Large ethnic differences are seen for inactivity, particularly for hours of television or video viewing per week (non-Hispanic blacks, mean = 20.4; non-Hispanic whites, mean = 13.1). Physical activity (>/=5 bouts of moderate to vigorous physical activity per week, 5-8 metabolic equivalents) is lowest for female and minority adolescents. Ethnic differences are far greater for inactivity than for moderate to vigorous physical activity.

CONCLUSION

Minority adolescents, with the exception of Asian females, have consistently higher levels of inactivity. Results vary by sex; males have higher inactivity and physical activity, whereas lowest physical activity is found for non-Hispanic black and Asian females, although Asian females also have low inactivity and low levels of overweight. Overall, efforts to reduce the problem of adolescent overweight should focus on increasing activity levels of adolescents, particularly female, older, and major minority subpopulations.

Brief communication: Tigaran (Point Hope, Alaska) tooth drilling

In a sample of 48 adult Tigarans (1300-1700 A.D.) from Point Hope, Alaska, 33 exhibited various degrees of periodontal disease, which, in 25, resulted in tooth loss (Schwartz, unpublished data). Although extreme examples of tooth wear were prevalent in the sample, carious infection was noted in only one individual, in whom the lower central incisors (I1S) had been affected. In the left I1, infection had spread through the root's apex into the alveolar bone, causing an abscess. The buccal (labial) side of the root of this tooth, just below the crown, bears a shallow, relatively flat-bottomed depression, with a small perforation into, as well as a second hole that fully penetrates, the root canal. Both of these features appear to have been produced by an implement, and, as they are associated with a diseased tooth, and ritualistic tooth shaping or drilling of any sort was, and is, not practiced among Arctic groups, their purpose was probably therapeutic. As such, this specimen appears to represent a case of precontact New World Arctic dentistry.

Longitudinal analysis of adolescent growth in height, fatness, and fat patterning in rural South African black children

Adolescent growth in height, fatness, and fat patterning was investigated in a sample of 79 rural South African black children studied longitudinally from 6-18 years. Data were analyzed relative to peak height velocity (PHV) to identify the phenomenon of "compensatory" growth in height during adolescence and to describe changes in fatness and fat patterning. Compensatory growth following PHV was clearly observed relative to NHANES data for African-Americans in that Z-scores for height at the start of the adolescent growth spurt were greater than those at the end of the spurt. Statistically significant differences in fatness and centralization between males and females did not occur until about 2 years after PHV was attained. Centralization of fat occurred in both sexes but more so in males. The lack of centralization in females was due to relatively greater triceps skinfold velocities. The rapid gain in post-PHV fatness in females may represent a physiological adaptation to an energetically sub-optimal environment, buffering the energetic costs of reproduction.