Blood pressure, fatness, and fat patterning among USA adolescents from two ethnic groups

The relationship between body composition and blood pressure among primary school children in Eastern Cape province, South Africa

Background

In South Africa, especially in the Eastern Cape province, despite reported high prevalence of underweight and obesity, little is known regarding the relationship of body composition (BC) with blood pressure (BP) in primary school children. Understanding the relationship between BC and BP in these children is important because it is associated with adverse effects on health and social repercussion in both adolescence and adulthood.

Aim

The aim of this study was to examine the relationship between BC and BP among South African primary school children.

Setting

This study was conducted on a cohort of primary school learners in the Eastern Cape Province of South Africa.

Methods

A school-based cross-sectional survey was conducted among 876 school children aged 9–14 years, using multistage sampling techniques. Body mass and stature were measured using a calibrated scale. Anthropometric measurements including weight, height, waist circumference, triceps, gluteal and subscapular were also collected. Body mass index, percentage body fat and waist-to-hip ratio were calculated.

Results

Of the 876 participants, 356 (40.6%) were boys and 520 (59.0%) were girls. The Spearman’s rho correlation coefficients revealed positive significant correlations between systolic BP with age (r = 0.171; p < 0.0001), stature (r = 0.205; p < 0.0001), weight (r = 0.277; p < 0.0001), body mass index (r = 0.243; p < 0.0001), waist circumference (r = 0.259; p < 0.0001), gluteal (r = 0.214; p < 0.0001), triceps (r = 0.203; p < 0.0001), subscapular (r = 0.167; p < 0.0001), body fat percentage (r = 0.206; p < 0.0001), fat mass (r = 0.257; p < 0.0001) and fat-free mass (r = 0.238; p < 0.0001). There was no statistically significant correlation between waist-to-hip ratio and systolic BP (r = 0.064; p = 0.059). In terms of diastolic BP, there existed no significant correlations with age (r = 0.026; p = 0.443) and waist-to-hip ratio (r = 0.002; p = 0.947). Collectively, the prevalence of hypertension was 76.4% in the normal group compared with those who were pre-hypertensive (18.4%) and hypertensive (5.3%). Girls showed a higher prevalence of pre-hypertension than boys (19.6% compared with 16.6%, respectively).

Conclusion

There is a relationship between most of the BC variables and BP in children. The screening of BP as part of physical examinations of school children is necessary for early prevention and intervention programmes for hypertension.

Obesity and blood pressure levels of adolescents in Abeokuta, Nigeria

BACKGROUND

We determined the prevalence of general and central obesity and their relationship with blood pressure levels among adolescents in Abeokuta, Nigeria.

METHODS

We selected 423 adolescents from seven schools in Abeokuta, Nigeria, using a multistage random-sampling technique. Body mass index (BMI), waist circumference (WC) and blood pressures were measured.

RESULTS

Twenty-one (5%) children had general obesity and 109 (24.5%) had central obesity. Of those with general obesity, 20 (95.1%) children were centrally obese. With simple linear regression analysis, BMI and WC explained 10.7 and 8.4%, respectively of the variance in systolic blood pressure (SBP), and 3.6 and 2.7%, respectively of the variance in diastolic blood pressure (DBP). Following logistic regression analysis, BMI was the major factor determining SBP levels (OR 0.8, 95% CI: 0.65-0.99, p < 0.05).

CONCLUSION

BMI remains an important anthropometric screening tool for high blood pressure in Nigerian adolescents.

Relationship of anthropometric measurements of body fat distribution to metabolic profile in premenopausal women

Regional fat distribution has emerged as an independent predictor of metabolic aberrations including glucose intolerance, hyperinsulinemia, insulin resistance, hyperlipidemia and hypertension. We investigated the comparative efficacy of various body fat distribution indices in predicting these aberrations. The relationship of circumferential ratios, skinfold measurements, and computerized tomography (CT)-derived indices of intra- and extra-abdominal fat distribution to the metabolic variables and blood pressure was examined in a cohort of healthy premenopausal women. All indices denoting preponderance of fat in the central, upper body or abdominal region were predictive of the metabolic profile. The subscapular skinfold, subscapular-triceps ratio, waist-hip ratio (WHR), and the CT derived intra-abdominal fat area (CT-IFA) were closely related to alterations in glucose and insulin concentrations independent of age and obesity. The WHR and CT-IFA were better predictors of plasma triglyceride levels and blood pressure profile and thus the overall aberrations than skinfold measurements. Despite a high degree of intercorrelation between the anthropometric indices measured, only the relationship of WHR to CT-IFA remained significant after adjusting for the effects of age and degree of adiposity, suggesting that WHR indexes not only the relative distribution of truncal to gluteofemoral subcutaneous fat but also the abundance of intra-abdominal or visceral fat depots. The greater reproducibility of CT-IFA and WHR also suggests that these measurements are the most useful in predicting the regional obesity-associated metabolic abnormalities with their morbidity and mortality risks.

Association of different obesity indices with blood pressure and blood lipids in children and adolescents

The aim of the present study was to compare individual associations of BMI, triceps skinfold (TSF), waist circumference (WC) and percentage fat mass (%FM) with blood pressure (BP) and blood lipids in children and adolescents. Cross-sectional data on BMI, TSF, WC, %FM as well as on BP, TAG and HDL were analysed in 4220 (BP) and 729 (lipids) 9–11-year-old children and 3174 (BP) and 536 (lipids) 13–16-year-old adolescents as part of the Kiel Obesity Prevention Study. All obesity indices were similarly associated with BP and blood lipids. In girls, WC had closer correlations to BP than BMI (systolic BP: 0·27 and 0·24 for BMI, 0·34 and 0·28 for WC in 9–11- and 13–16-year-olds). Subjects with an obesity index ≥ 90th percentile had higher prevalences of elevated BP and blood lipids than subjects with a normal index. In children with normal BMI or WC, an additionally elevated second obesity index was associated with a 2·5–7·4-fold higher prevalence of high BP when compared with children with normal indices. In adolescents, an elevated WC plus an elevated second obesity index was associated with a 2·6–8·2-fold higher prevalence of high BP when compared with adolescents with an elevated WC plus a normal second index. We conclude that (i) both BMI and WC are appropriate to estimate CVD risk, (ii) the use of a second obesity index is recommended in children with normal BMI or normal WC as well as in adolescents with elevated WC and (iii) all obesity indices seemed to be appropriate for risk assessment.

Somatotype and blood pressure of rural South African children aged 6-13 years: Ellisras longitudinal growth and health study

BACKGROUND

Physique has been useful in assessing the outcome of underlying growth and maturity processes, which leads to a better understanding of variation in child and adult health. However, a high endomorphy rating has been associated with hypertension in adults, posing a serious threat to their health status, while receiving little attention in children.

AIM

The study examined the association between somatotypes, body mass index (BMI) and blood pressure (BP) in 6-13-year-old rural children, in Ellisras, South Africa.

SUBJECTS

A total of 1902 subjects (980 boys and 922 girls) aged 6-13 years were studied as part of the Ellisras Longitudinal Study. Height, weight, four skinfold sites, two breadths, and two girths were measured according to the International Society for the Advancement of Kinanthropometry (ISAK). The Heath-Carter method of somatotyping was used, together with internationally recommended cut-off points for BMI in children. Hypertension, defined as the average of three separate BP readings, where the systolic or diastolic BP is greater than or equal to the 95th percentile for age and sex, was determined.

RESULTS

The prevalence of hypertension ranges from 1 to 5.8% in boys and 3.4-11.4% in girls. The prevalence of overweight ranges from 1.1 to 2.9% in boys and 0.6-4.6% in girls. Systolic BP and BMI showed a significant positive correlation at age 6 years (r = 0.436) and 10-13 years (r = 0.180-0.246 in boys and r = 0.221-0.271 in girls). Diastolic BP showed an insignificant correlation with the BMI and somatotype components in boys and girls.

CONCLUSION

A significant association exists between BP and BMI, and ectomorphy components even after being adjusted for age, gender and height. The need to manage hypertensive individuals is evident in this sample to combat this chronic disease from an early age. Follow-up studies should investigate the relationship between BP and the dietary intake of these children.

Relationship between body composition and blood pressure in Bahraini adolescents

The objective of the present study was to examine the relationship between body composition and blood pressure (BP) in Bahraini adolescents. A sample of 504 Bahraini schoolchildren aged 12–17 years (249 boys and 255 girls) was selected using a multi-stage stratified sampling procedure. BP measurements were performed on the students. Anthropometric data including weight, height, waist circumference (WC), hip circumference, and triceps, subscapular and medial calf skinfold thicknesses were also collected. BMI, percentage body fat, waist:hip (WHR), and subscapular:triceps skinfold ratio were calculated. Mean systolic BP and mean diastolic BP were higher in males than in females. Weight and height in boys and weight only in girls were significantly associated with systolic BP independent of age or percentage fat. Nearly 14% of the adolescents were classified as having high BP. BMI and percentage body fat were significantly and positively associated with the risk of having high BP in the boys and girls. Adolescents with high WHR or WC, as indicators for central obesity, tended to have higher BP values. The results from the present study indicate that obesity influences the BP of Bahraini adolescents and that simple anthropometric measurements such as WHR and WC are useful in identifying children at risk of developing high BP. These findings together with the known tracking of BP from adolescence into adulthood underline the importance of establishing intervention programmes in order to prevent the development of childhood and adolescent obesity.

The association of fat patterning with blood pressure in rural South African children: the Ellisras Longitudinal Growth and Health Study

BACKGROUND

Hypertension is one of the major causes of death in developed and underdeveloped nations. Essential hypertension and obesity may have their inception in childhood, with little data in African children to support these findings. Objectives were to determine the prevalence of overweight and hypertension in rural children in South Africa. Additionally, the association between fat-patterning ratios and blood pressure (BP) was investigated.

METHODS

Data were collected from 1884 subjects (967 boys and 917 girls), aged 6-13 years, participating in the Ellisras Longitudinal Study. Height; weight; and triceps, biceps, subscapular, and suprailiac skinfolds were measured according to the protocol of the International Society for the Advancement of Kinanthropometry. Skinfold ratio was used as an indicator of the central pattern of body fat. Internationally recommended cut-off points for body mass index (BMI) were used. Hypertension, defined as the average of three separate BP readings where the systolic BP or diastolic BP is >or=95th percentile for age and sex, was determined.

RESULTS

The prevalence of hypertension ranged from 1 to 5.8% for boys and 3.1 to 11.4% for girls, and that of overweight from 1.1 to 2.9% for boys and 0.6 to 4.6% for girls. The association between high systolic BP and high BMI was -3.0, while that for high diastolic BP and high BMI was -0.68.

CONCLUSIONS

The prevalence of hypertension is evident from the age 6 years for girls, while that of overweight was low. Overweight became evident from the age 10 to 13 years for both sexes. A significant association between high diastolic BP and high BMI was noted, while children with low BMIs were less likely to be hypertensive. Investigating habitual physical activity, fitness and dietary patterns will shed more light on the association of fat patterning and BP in this population.

Mini Review: Physical activity and fitness and its relations to cardiovascular disease risk factors in children

OBJECTIVES

This paper aim to review the newest literature linking physical inactivity and low fitness to metabolic disorders including cardiovascular disease (CVD) risk factors and obesity.

METHODS

There is a rationale for early prevention of CVD if (a) children have a risk factor profile, where risk for future disease is increased, (b) physical activity and CVD risk factors track into adulthood, and (c) increased physical activity can improve the risk factor profile. We reviewed the evidence for a progressive evolution of atherosclerosis starting in childhood, and also that physical activity decreases the rate of the process through several mechanisms. Among the central mechanisms mediating the effect of physical activity are (a) increased insulin sensitivity, (b) a non-insulin-dependent glucose uptake, which causes lower insulin release, (c) an improved ratio between HDL and LDL cholesterol because of increased activity of lipoprotein lipase, and d) improved function of other metabolic hormones and enzymes for fat metabolism.

RESULTS

The association between CVD risk factors and physical activity/fitness is weak, when risk factors are analysed isolated. In the normal healthy population of children, studies have shown that risk factors cluster and this clustering is strongly related to low physical activity or fitness. In European children it has been found that as many as 15% of 9-y-old children has clustered risk. Most of the overweight and obese children are among these, but many of the children are lean inactive children, who may later become overweight because of insulin resistance.

CONCLUSION

It can be concluded that there is a large potential for primary prevention of CVD in European children, and lifestyle changes including increased physical activity as one of the key actions should be initiated.

Anthropometric and psychosocial changes in obese adolescents enrolled in a Weight Management Program

OBJECTIVE

To determine short- and long-term effects of the Bright Bodies Weight Management Program on obese adolescents and to further observe if a diet or nondiet approach is more successful.

DESIGN

Twenty-five obese adolescents completed a 1-year, comprehensive weight-management program and returned for a 2-year follow-up. Adolescents were 11 to 16 years old (17 female, eight male) with mixed ethnic backgrounds. Although the program emphasizes a nondiet approach, eight children requested a structured meal plan (diet approach), while 17 were taught to make better food choices (nondiet approach). Body mass index (BMI) z score, body fat percent, and self-concept were measured at 0, 1, and 2 years. Outcomes were analyzed for the entire group and by diet method groups.

STATISTICAL ANALYSIS

Changes in outcome variables were evaluated using covariance pattern models for repeated measures.

RESULTS

At 1 year, the entire group (N=25) demonstrated a decrease in BMI z score (P <.001) and body fat percent (P <.001), while self-concept scores increased (P <.001). At 2 years, the decrease in BMI z score was still significant (P =.004) and body fat percent and self-concept scores remained improved, although not significant compared to baseline (P =.15 and P =.10, respectively). When comparing dietary approaches, the dieting group (n=8) tended to show favorable results short-term for BMI z score at year 1 (P =.11), but by year 2, the nondieting group (n=17) further improved BMI z score (P =.006), while the dieting group reverted toward baseline.

CONCLUSIONS

The Bright Bodies Weight Management Program was successful at decreasing BMI z scores both short and long term. In a separate analysis, dieting showed more superior short-term results, but a nondiet approach demonstrated improved long-term results.

Effect of Birth Weight on Blood Pressure and Body Size in Early Adolescence

The fetal programming theory that birth weight contributes to blood pressure or body size in later life is examined in this study. A prospective longitudinal study was conducted on subjects who were examined as newborns and prospectively interviewed and re-examined at 11 to 14 years old. Low birth weight (<2500 g) was present in 36% of the sample. The adolescent examination included measurements of blood pressure (BP), both auscultation and oscillometric methods; anthropometrics (height, weight, and body mass index [BMI]); health status; and health behaviors. Data were analyzed on 250 subjects. Correlation coefficients of birth weight with all BP measures were nonsignificant, except for the last auscultated diastolic BP ( r =0.19, P <0.01), which had a positive relationship. The simple correlation coefficients of birth weight with adolescent body size were significant and positive for weight and BMI. After multiple linear regression analyses with adjustments for age, Tanner stage, and gestational age, there was no significant effect of birth weight on adolescent weight or BMI. No significant correlations were detected for ponderal index at birth with adolescent measures. This study, which includes a substantial portion of low-birth-weight cases (36%), indicates that birth weight does not correlate negatively with later BP. These results do not support the low-birth-weight theory and indicate that childhood factors that are more proximal have a greater effect on adolescent BP than intrauterine factors.

Established and recently identified coronary heart disease risk factors in young people: the influence of physical activity and physical fitness

Epidemiological studies have identified several risk factors for coronary heart disease (CHD), many of which are present in young people. [For the purpose of this review, the phrase "young people" embraces both children and adolescents.] One such risk factor is hypertension. In adults, exercise is thought to have a positive effect on blood pressure levels; however, findings are inconclusive for young people. Despite its association with CHD, obesity is on the increase in Western society's young population; prevention and intervention during early years is needed. An active lifestyle is considered to have a beneficial effect on body fatness. Lipoprotein profiles are directly associated with CHD status. In adults, there is some evidence that physical activity and/or fitness have a favourable effect on lipoprotein levels. Although information regarding the younger population is more ambiguous, it tends to concur with these findings. High levels of lipoprotein(a), are considered an independent risk factor for CHD. Relatively little has been written on young people, although some studies have postulated a favourable relationship with physical activity. An inverse relationship between aerobic fitness and CHD has been confirmed in adults; an association is not as easily verified for young people. Physical activity is similarly deemed to have a beneficial effect on health status. A high-fat diet has been linked to CHD in adults, and evidence to date reports similar findings for young people. Smoking increases the risk of CHD and even moderate smoking during youth could have damaging long-term consequences. There is some evidence that smoking is related to physical activity and fitness levels in young people. In adults, high levels of homocyst(e)ine have been associated with CHD. As yet, little has been written on the relationship between physical activity or physical fitness and homocysteine status in young people. High levels of plasma fibrinogen have been linked to CHD. Several studies have explored the relationship between plasma fibrinogen and physical activity and/or fitness in adults, but findings are inconclusive; for young people, the ambiguity is even greater. C-reactive protein is a molecular marker for CHD but, to date, little attention has been given to this aspect, especially amongst young people. The link between high levels of plasminogen activator inhibitor-1 and CHD has been confirmed, although the essence of this relationship is not established. There is a paucity of data on the younger population and the relevance of collating such information is questionable. For the younger population, most research is limited to the established CHD risk factors and further investigations of recently identified CHD risk factors are needed.

Body size, fat distribution, menarcheal age and blood pressure in 14-year-old girls

BACKGROUND

The relationships between body size and fatness and blood pressure are generally acknowledged. The majority of the few studies that have examined the effect of fat distribution and maturation rate on blood pressure have used secondary sex characteristics as the measure of maturity. The aim of the present study is to examine the associations between blood pressure and relative weight, fat distribution, recalled menarcheal age and occurrence of menstruation (yes/no) in a sample comprising of 1149 14-year-old girls.

METHODS

Systolic and diastolic blood pressure (DBP), height, weight and body circumferences were measured using standard protocols. Fatness was expressed as body mass index (BMI, kg/m2), whereas fat distribution was estimated by using waist-to-hip ratio. The girls' maturity status was assessed from exact recalled date of menarche. One-way analysis of covariance and multiple linear regression analyses were used to determine the strength of association among systolic blood pressure (SBP), DBP and BMI, menarcheal age and indices of fat distribution.

RESULTS AND CONCLUSION

Height and BMI are significantly associated with SBP. Relative weight is the most important factor related to SBP independently of chronological age and maturity status. Height and age at menarche are significantly associated with DBP. Height of 14-year-old girls shows the same strength of association with SBP and DBP, whereas maturity status negatively correlates with DBP. Fat distribution shows no effect on the level of DBP in girls.

The association between high blood pressure, physical fitness, and body mass index in adolescents

BACKGROUND

The aim of this study was to analyze the association of fitness and fatness with blood pressure (BP) and hypertension. This was a cross-sectional study of 13,557 boys and girls 15-20 years of age. Fitness was estimated from a shuttle run test, fatness from body mass index (BMI), and BP was measured sitting after 5 min of rest. Other lifestyle variables were self-reported.

RESULTS

Boys had a higher systolic BP (SBP) than girls. A low physical fitness level and high BMI were independently associated with a high BP and risk of having hypertension in both girls and boys. Interaction was found between BMI and fitness. In a stratified analysis an odds ratio (OR) of 3.99 was found for hypertension in girls with a BMI > 25 kg m(-2) compared to lean girls if all had a low fitness level, and an OR of 2.14 for a high BMI in girls with a high fitness level. In boys, OR for high versus low BMI were 3.23 in the low fit and 2.34 and 2.50 in the middle and upper tertile of fitness, respectively.

CONCLUSIONS

Fitness and BMI were independently associated to BP. BMI was a stronger predictor of hypertension in those with a low fitness level, especially in girls.

Effects of socioeconomic status on the obesity knowledge of adolescents from six Latin American cities

OBJECTIVE

To examine the effects of socioeconomic status (SES) on the obesity knowledge of adolescents in six Latin American cities.

DESIGN

Data were collected using an anonymous, self-administered questionnaire consisting of demographic questions and a 25-item multiple-choice obesity knowledge test. Test items were clustered under five topics: the fat and calorie content of foods and beverages; weight loss methods; energy expenditure; food preparation methods; and the relationship between obesity and health.

SUBJECTS

A total of 1272 ninth grade students from higher and lower SES families were recruited at schools in Buenos Aires, Argentina (n=195); Guatemala City, Guatemala (n=212); Havana, Cuba (n=213); Lima, Peru (n=218); Panama City, Panama (n=195); and Santiago, Chile (n=239).

RESULTS

Mean test scores reflected a low level of obesity knowledge among adolescents from higher and lower SES groups in all six cities. Nevertheless, a trend for higher scores emerged in favor of adolescents from wealthier families. This income effect persisted after controlling for gender and weight status. The weakest knowledge areas among youth from the higher SES groups were food preparation methods and the relationship between obesity and health while those for adolescents from the lower SES groups were the fat and calorie content of foods and beverages and the relationship between obesity and health. Classroom instruction about obesity was generally more available to students from the higher SES groups. The majority of adolescents from both SES groups were interested in learning more about weight loss methods, energy expenditure, and the fat and calorie content of foods and beverages. The topic of least interest was the relationship between obesity and health.

CONCLUSION

These preliminary findings suggest a need for more obesity education programs for adolescents, especially for those living in poverty.

Abnormal epinephrine release in young adults with high personal and high parental blood pressures

BACKGROUND

Increased activity of the sympathetic nervous system has been proposed as a cause of high blood pressure (BP) and may be related to diet and body weight. To determine the role of these factors in predisposition to high BP, we studied 100 young adults with high or low BP from families in which both parents had either high or low BP.

METHODS AND RESULTS

Plasma catecholamine, glucose, and insulin levels were measured before and after an oral glucose load. There was a significant correlation between fasting plasma norepinephrine and mean arterial pressure (P=.001). Subjects with high BP, irrespective of parental BP, were heavier (P=.003) and fatter (P=.002) and had a greater rise in plasma insulin (P=.003) following glucose than those with low BP. Offspring with high BP whose parents also had high BP showed an unexpected rise in plasma epinephrine (P=.004) following glucose. This adrenal medullary response was not the result of high parental or high personal BP alone as it was not seen in offspring with low BP whose parents had high BP or in offspring with high BP whose parents had low BP.

CONCLUSIONS

Irrespective of family history, high BP is associated with increased body weight and hyperinsulinemia and reflects personal environment and behavior. However, abnormal epinephrine release is characteristic of the combination of genetic, environmental, and behavioral factors that is associated with high personal BP and a familial predisposition to high BP.

Insulin resistance syndrome in adolescents

To explore whether the so-called insulin resistance syndrome can be identified in adolescents, serum insulin level was measured in 842 healthy Swedish adolescents (462 boys and 380 girls) and the values were related to current serum lipoprotein and apolipoprotein values (triglyceride [TG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C), low-density lipoprotein cholesterol [LDL-C], apolipoprotein [apo] A-I, apo B, and lipoprotein(a)), blood pressure (BP), and anthropometric measurements and previous physical growth. Mean serum insulin values were higher in 14-year-olds as compared with 17-year-olds and were highest in midpuberty. Adolescents with a high serum insulin had a higher attained height and weight during infancy and childhood. Obesity (body mass index [BMI] > 30 kg/m2) was found in 1% of both boys and girls, and hypertensive BP levels were found in 3% of the boys and 1% of the girls. Controlling for age, serum insulin correlated positively with BMI (r = .36 and .25 in boys and girls, respectively), TG (r = .32 and .14), LDL-C (r = .17 and .24), and apoB (r = .23 and .23) and negatively with HDL-C (r = -.13 and -.21). High serum insulin, TG, LDL-C, and BP and low HDL-C clustered in adolescents with high BMI. In conclusion, the findings of this study indicate that features typical of the insulin resistance syndrome are already present in adolescents.

Commentary: strength and importance of the relation of dietary salt to blood pressure. Intersalt Steering and Editorial Committee

Images

Correlates of blood pressure in Seventh-Day Adventist (SDA) and non-SDA adolescents

OBJECTIVE

This comparative study was designed to discover early determinants of systolic (S) and diastolic (D) blood pressure (BP) elevations in 138 Seventh-Day Adventist (SDA) and 89 non-SDA male and female adolescents (median age, 17 years) living at three residential secondary schools in North Carolina.

METHODS

Measurements were made of blood pressure, body weight, and height, and information was collected on lifestyle factors, dietary intake, and other behaviors, including exercise, religiosity, Type A behavior, and anger, by questionnaire. Multiple stepwise regression analyses were performed with BP, either SBP or DBP, as the independent variable.

RESULTS

A significant direct association was found only between body weight and BP, but weak associations were shown between BP and other variables, including exercise, diet, religiosity, Type A behavior, and anger. Male and female SDA students showed significantly higher SBPs and DBPs than did non-SDA adolescents though the differences were small (approximately 5 mm for each sex).

CONCLUSIONS

These findings suggest that the higher BP values of SDA adolescents, who were all practicing lacto-ovo-vegetarians, compared to similarly aged health-conscious non-SDAs, are determined more by eating behaviors that contribute to gains in body weight than by any other lifestyle variable. Furthermore, these data support the notion that the BP-protective effects of the vegetarian diet may not emerge in these SDA youth until early adulthood.

Is body fat distribution associated with cardiovascular risk factors in childhood?

The authors studied the association of cardiovascular risk variables with body fat distribution (BFD) in a cross-sectional sample of 743 Texas schoolchildren of both sexes ages 6-14 years. This association is well known in adults and several useful indices of BFD are available. Whether they are applicable to children remains a question of importance for epidemiological investigations in this age group. Canonical correlations between anthropometric (five skinfolds, four circumferences) and risk (blood pressures, cholesterol, pulse) variables ranged from 0.37 to 0.82 depending on sex/age group (p < 0.01). The skinfold vector suggested an association of risk with central fat at most but not all ages. The circumference vectors, on the other hand, suggest that size or fatness, not BFD, was related to risk. Partial correlation and stepwise regression of fatness and BFD indices with cardiovascular risk factors as dependent variables, showed that 'fatness' or 'size' was more clearly associated with risk factors than BFD. The variables most consistently entering the regression were hip circumference and sum of skinfolds. These results contrast with studies of adults or sexually mature adolescents, in which BFD is more clearly related to CV risk variables and the hip circumference is a 'low-risk' variable.

Normotensive young men with family histories of hypertension gain weight and decrease their intraerythrocyte sodium content during a 5-year follow-up

Young normotensive men matched for age and body mass index with (n = 16) and without (n = 13) family histories of hypertension were investigated at baseline and after 5 years of follow-up with respect to blood pressure, body weight and intracellular sodium content. Subjects with positive family histories of hypertension increased significantly in body weight (from 81.9 +/- 11.5 kg to 89.5 +/- 11.4 kg, P less than 0.001) compared to subjects with negative family histories of hypertension (from 79.9 +/- 10.8 kg to 80.7 +/- 12.2 kg, NS). Their blood pressure did not differ initially (137 +/- 12/75 +/- 11 mmHg vs. 135 +/- 8/72 +/- 9 mmHg), but was reduced in subjects without family histories of hypertension (to 125 +/- 3/68 +/- 13 mmHg) in the follow-up examination. At follow-up, body mass index showed a positive correlation with blood pressure among subjects with positive family histories of hypertension (r = 0.77, P less than 0.001). At baseline, subjects with hypertensive fathers had significantly higher intraerythrocyte sodium levels than subjects with normotensive parents. At re-examination 5 years later, this difference was no longer present. We conclude that normotensive subjects with positive family histories of hypertension are predisposed to gain weight rather than to show an increase in blood pressure at this age. Normalization of intracellular sodium content, as found in the present study, could be a consequence of this weight gain and the ensuing metabolic adaption.

The association of body fat location with haemodynamic and metabolic status in men and women aged 21-60 years

The importance of body fat location as a predictor of metabolic aberrations was evaluated in 214 males and 244 females [aged 21-60] randomly selected from the patients of one general practice of Castel D'Azzano (Italy). The metabolic pattern, indexed by blood pressure, blood glucose, uric acid, serum triglycerides, HDL- and LDL-cholesterol was summarized in a haemodynamic-metabolic score (HMS). Association of HMS with age, anthropometric variables (skinfold thicknesses, girth lengths) and degree of overweight (body mass index, BMI) was evaluated in males and females using multiple regression analysis. Body fat location was associated with metabolic status independent of age in both sexes. This association was also independent of the degree of overweight. BMI, in general, was associated with HMS to a greater extent than anthropometric variables, except for waist girth; when its effect was taken into account BMI did not significantly improve the prediction power of HMS values in males. Among skinfolds, epimesogastric showed in both sexes the highest association with HMS. These results support the abdominal adiposity hypothesis and suggest that waist circumference could be a good index for assessing metabolic status. The abdominal location of adipose tissue, more than just the degree of overweight, could play a role in obesity related disorders.

Interrelationships between psychological factors, overweight, and blood pressure in adolescents

Relationships between psychological factors and physical factors such as body mass, overweight, and blood pressure were examined in a sample of black and white adolescents enrolled in health science courses. Black female adolescents were significantly more overweight and obese than either other group. Psychological factors were not significantly associated with body mass (weight/height) for females. A small percentage of the variance in body mass for black (6%) and white (4%) males was explained by Trait Anger, the frequent experience of anger and the intensity of anger (S-Anger-Reaction/TP) in pressure situations. Trait Anger also significantly (p less than 0.01) discriminated between black male adolescents who were normal weight and those 20% overweight for age and height. The relationships between traditional risk factors and blood pressure among adolescents who were 20% underweight, normal weight, and 20% overweight for age and height suggest that few traditional risk factors contribute significantly to the prediction of blood pressure in overweight adolescents. In contrast, psychological measures of suppressed anger (Anger-In, Anger Expression) were significantly (p less than 0.001) associated with blood pressure among overweight adolescents. The findings regarding the associations between overweight and psychological factors are complex. Prospective studies using better measures of overweight are needed to clarify the processes involved.

Obesity hypertension

Obesity and hypertension are two major risk factors for the cardiovascular system. Whereas arterial hypertension increases afterload to the left ventricle, obesity produces an increase in stroke volume and increases preload. As a result of this double burden, the heart adapts with eccentric left ventricular hypertrophy. Contractility becomes impaired early in the course of obesity hypertension, and ventricular ectopy is observed. As a consequence, the obese hypertensive patient is at a high risk for congestive heart failure and sudden death. Despite the synergistic effects of obesity and hypertension on the heart, patients appear to be relatively protected from nephrosclerosis and coronary artery disease. These epidemiologic observations are supported by the pathophysiologic changes that take place in obesity hypertension. At any given level of arterial pressure, cardiac output and renal blood flow are elevated in obese hypertensive patients, whereas systemic and renal vascular resistance are decreased when compared to lean hypertensive patients. Because total peripheral resistance is considered the hemodynamic hallmark of arterial hypertension, systemic vascular complications may be less pronounced in obesity hypertension. Weight loss decreases preload, afterload to the left ventricle, and the sympathetic drive to the heart. Protecting the heart from these hypertrophic stimuli should be a major goal of preventive cardiology.

Body fat patterning and blood pressure in children and young adults. The Bogalusa Heart Study

The relationship of central body fat (measured by subscapular skinfold) and peripheral body fat (measured by triceps skinfold) to blood pressure was investigated in 3784 subjects aged 5 to 24 years old from the biracial community of Bogalusa, Louisiana. After adjustment for height, age, sex, and race, significant relationships were found for both central body fat (r = 0.19 and 0.14, p less than 0.0001) and peripheral body fat (r = 0.15 and 0.12; p less than 0.0001) with systolic and diastolic (fourth phase) blood pressure, respectively. However, the relationship between peripheral body fat and blood pressure, after controlling for the level of central body fat, was negligible (r = 0.00 and 0.01 for systolic and diastolic blood pressure, respectively). In contrast, the central body fat-blood pressure relationship remained statistically significant even after controlling for the peripheral body fat level. For central body fat, the partial correlations with systolic blood pressure were highest in young children (r = 0.15), dropped slightly during adolescence (r = 0.12), and became nonsignificant only in 18- to 24-year-old female subjects; correlations remained high in both black and white 18- to 24-year-old male subjects (r = 0.18 and 0.16, respectively). Mean levels of systolic blood pressure from the lowest to the highest quartile of central body fat ranged from 100.4 to 108.9 mm Hg. The adult hypertension-central body fat relationship, which has been shown by others, appears to exist in children. Continued efforts at early identification and prevention of obesity in children are warranted.

The association of the ratio of waist to hip girth with blood pressure, serum cholesterol and serum uric acid in children and youths aged 6-17 years

To determine whether the association of the ratio of waist to hip girth with cardiovascular risk factors exists in prepubertal children and pubertal youths, the ratio was related to blood pressure, serum cholesterol and serum uric acid levels in children and youths aged 6-17 yr in the Health Examination Survey. In these samples drawn from the United States population, the ratio declined with increasing age. Boys had consistently higher ratios than girls. Black-white differences were inconsistent. The ratio was lower in girls whose menstrual periods had started at each age after 10. The ratio was significantly associated with systolic blood pressure in youths and with diastolic blood pressure in children independent of confounders. It was also significantly associated with serum uric acid but not serum cholesterol independent of confounders among youths. Longitudinal studies are needed of greater abdominal relative to lower body fat deposits in children and youths and risk of cardiovascular disease in adulthood.

Blood pressure in puberty

The effects of sexual maturation, height, weight, body mass index, triceps skinfold and heart rate on systolic and diastolic blood pressure were studied among 13-year-old children in North Karelia, Eastern Finland. Cross-sectional and two-year longitudinal data were analyzed for 851 children in the six schools participating in the North Karelia Youth Project. In boys, the levels of both systolic and diastolic blood pressure increased during puberty. In girls, the level of systolic blood pressure did not change, but diastolic blood pressure increased as much as in boys. The change in systolic blood pressure was found to be associated with physical growth and stage of sexual maturation. Physical growth seemed to contribute more to the change in the level of systolic blood pressure than the stage of sexual maturation did.

Hypertension and diabetes in obesity: a review and new ideas on the contributing role of ions

Ion metabolism in obesity-associated hypertension is reviewed. A hypothesis is presented which proposes that ion imbalances in obesity may play an etiological role in obesity-associated diabetes mellitus as well. It is suggested that the rise in intracellular calcium--secondary to reduced sodium, potassium-activated adenosine triphosphatase (Na,K-ATPase) activity--may aid in the development of increased vascular tone and decreased glucose tolerance.

The relative contribution of body fat and fat pattern to blood pressure level

Although the association between body weight and blood pressure is irrefutable, body fat mass and blood pressure level may not necessarily be directly related. To clarify the relative contribution of fat mass to blood pressure level, we analyzed data on 399 adults consecutively entering a weight control program. Although most subjects were notably overweight (mean ideal body weight 177%), the population represented a wide spectrum of body weights and blood pressure levels. Study parameters included body fat mass (by total body water, 40K, and Steinkamp formula), lean body mass, body build (chest to height ratio), fat cell number and size from bilateral buttock biopsy specimens, upper fat pattern by arm to thigh circumference ratio, and central fat pattern by subscapular to triceps skinfold ratio. Our results concurred with previously noted correlations between obesity and blood pressure (as mean arterial pressure): weight (r = 0.44), percentage of body fat (r = 0.19), and absolute fat mass (r = 0.38; all p less than 0.01); however, lean body mass, age, and body build correlated highly with both fat mass and mean arterial pressure, thereby confounding this relationship. Multivariate analysis was performed to evaluate the relative contribution of fat mass to mean arterial pressure in the presence of these and other potentially confounding variables. Lean body mass, age, body build, and an upper body fat pattern were found to contribute significantly to the variation in mean arterial pressure (p less than 0.01). In their presence, percentage of body fat, absolute fat mass, central fat pattern, fat cell characteristics, and age of onset of obesity did not significantly improve the predictability of mean arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgyny in fat patterning is associated with obesity in adolescents and young adults

Recent work suggests that android or male-type obesity is characterized by fat cell enlargement on the trunk and upper body. This implies adult differences in patterns of body fat distribution may have developmental origins connected with differences in maturation or age of onset of obesity. To investigate this, we studied adolescent females (N = 455, 12 years), males (N = 527, 14 years) and young adults (N = 393 females and N = 413 males, 17 years) of the US Health Examination Survey. Five skinfolds and five maturity indicators were available. Individuals were classed as normal weight, overweight or obese on the basis of the body mass index (WT/HT2). Fat patterning was studied by principal components analysis of the log residual skinfold thickness at the five sites, which revealed trunk/extremity and upper/lower trunk fat distribution components in all sex/age groups studied. The means of both components were significantly (P less than 0.05) greater in obese than in normal weight individuals indicating that obesity in adolescence and young adulthood consists of fat concentrated on the upper aspect of the trunk. The effect was independent of maturity, which was a significant correlate of the trunk/extremity patterning component only and in males only. Advanced physiological maturity is probably not a determinant of adult patterns of body fat distribution, but obesity which occurs in adolescence may be.

The Diabetes Alert study: growth, fatness, and fat patterning, adolescence through adulthood in Mexican Americans

Diabetes Alert is a multidisciplinary genetic and epidemiological study of Type II (non insulin-dependent) diabetes in Texas Mexican Americans. We report the anthropometry of 1,155 individuals 10 to 70 or more years with particular reference to overweight, fatness, and anatomical fat patterning in the sample. Children ages 10-18 of both sexes are growing at the 50th percentile of the reference data (U.S. Health and Nutrition Examination Survey-1) for height, Wt/Ht2, and triceps and subscapular skinfolds. Adults are well below median height but well above median Wt/Ht2 and skinfolds. Prevalence of obesity (Wt/Ht2 greater than or equal to 30) among adults is typically 30% or higher by age 30. Diabetics compared to age/sex-matched non diabetics have shorter sitting heights, have more upper body fat (subscapular skinfold), have less lower body fat (lateral calf skinfold), and were heavier at maximum weight and at age 18. The ratio of lower to upper body fat distribution decreases over the life cycle, being highest at adolescence and lowest at ages 40-50 in both sexes. Our results show a precipitous weight gain after maturity in the sample and an association of diabetes with differences in anatomical fat patterning. The age-related changes in fat patterning need to be explained in terms of their ecological and genetic influences.