Establishing a standard definition for child overweight and obesity worldwide: international survey.

OBJECTIVE: To develop an internationally acceptable definition of child overweight and obesity, specifying the measurement, the reference population, and the age and sex specific cut off points. DESIGN: International survey of six large nationally representative cross sectional growth studies. SETTING: Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States. SUBJECTS: 97 876 males and 94 851 females from birth to 25 years of age. MAIN OUTCOME MEASURE: Body mass index (weight/height(2)). RESULTS: For each of the surveys, centile curves were drawn that at age 18 years passed through the widely used cut off points of 25 and 30 kg/m(2) for adult overweight and obesity. The resulting curves were averaged to provide age and sex specific cut off points from 2-18 years. CONCLUSIONS: The proposed cut off points, which are less arbitrary and more internationally based than current alternatives, should help to provide internationally comparable prevalence rates of overweight and obesity in children.

PIP: This study aimed to develop an internationally acceptable definition of child overweight and obesity, specifying the measurement, reference population, and age and sex specific cut off points. Data on body mass index (weight/height) were obtained from 6 large nationally representative cross sectional surveys on growth from Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the US. The study included 97,876 males and 94,851 females from birth to 25 years of age. For each of the surveys, centile curves were drawn that at age 18 years passed through the widely used cut-off points of 25 and 30 kg/sq. m for adult weight and obesity. The resulting curves were averaged to provide age- and sex-specific cut-off points from 2 to 18 years. The proposed cut off points, which are less arbitrary and more internationally based than current alternatives, should help to provide internationally comparable prevalence rates of overweight and obesity in children.

Workshop on childhood obesity: summary of the discussion.

Childhood obesity is rapidly emerging as a global epidemic that will have profound public health consequences as overweight children become overweight adults. To address this problem, action is needed at national and international levels. However, well-documented evidence of the trends in and global prevalence of obesity in children and adolescents is required to develop sound public health policies. There is no internationally acceptable index to assess childhood obesity nor is there an established cutoff point to define overweight in children. The purpose of the workshop was to establish a reasonable index with which to assess adiposity (overweight) in children and adolescents worldwide. We present here a summary of the discussion on the establishment of an index. The participants concluded that although body mass index (BMI; in kg/m2) is not a perfect measure in children because it covaries with height, it has been validated against measurements of body density. Because a consistent and pragmatic definition for overweight in children and adolescents is required, BMI may therefore be appropriate. However, other alternatives may be considered in the future. The group suggested a scheme for cutoff points for children and adolescents based on internationally accepted BMI cutoff points for adult morbidity of 25 and 30 to identify grade 1 and grade 2 overweight, respectively. Use of these cutoff points would provide a new approach to identifying childhood obesity and make the definition for children and adolescents consistent with that for adults.

Introduction: the use of body mass index to assess obesity in children.

The International Obesity Task Force (IOTF) was established in 1994 to address the increase in the worldwide prevalence of obesity. The goals of the IOTF are to 1) raise awareness in the population and among governments that obesity is a serious medical condition, 2) develop policy recommendations for a coherent and effective global approach to the management and prevention of obesity, and 3) implement appropriate strategies to manage and prevent obesity on a population basis worldwide. To assess the global prevalence of obesity in children and adolescents, the IOTF convened a workshop on childhood obesity to determine the most appropriate measurement to assess obesity in populations of and adolescents around the world. At the workshop, a variety of issues related to this problem were considered--including the best measure of fatness, the effect of application of a variety of existing standards on the prevalence of obesity in the same population, and the role of factors such as visceral adiposity and natural history in the definition of obesity. This article and those that follow represent the information presented at the workshop. The workshop concluded that the body mass index (BMI; in kg/m2) offered a reasonable measure with which to assess fatness in children and adolescents and that the standards used to identify overweight and obesity in children and adolescents should agree with the standards used to identify grade 1 and grade 2 overweight (BMI of 25 and 30, respectively) in adults.

Effects of antioxidants on vascular health.

Substantial in vitro and animal model evidence implicates the free radical-mediated oxidation of low density lipoprotein and its subsequent preferential uptake by macrophages in the arterial intima as an important factor in the development of vascular disease. In addition, antioxidants which prevent the oxidation of LDL in vitro also reduce the severity of vascular disease in animal models. Although some epidemiological studies also suggest that inadequate antioxidant status is related to the development of vascular disease, particularly cardiovascular disease, results from intervention trials have been contradictory. Whereas vitamin E may have a role in reducing the incidence of vascular disease, evidence is less strong for vitamin C, flavonoids and beta-carotene. Additionally, supplementation with some antioxidants such as beta-carotene may increase the incidence of cancer in high risk groups. Although increasing antioxidant intake is generally beneficial for health, this should perhaps be achieved by an increased dietary intake of antioxidant-rich foods rather than by use of supplements.

alpha-Tocopherol binding activity of red blood cells in smokers.

Despite high plasma levels of vitamin E, red blood cell membranes contain relatively low levels of vitamin E. This suggests the existence of a selective vitamin E uptake/regeneration system in human red blood cell membranes. alpha-Tocopherol binding sites on human red blood cells are thought to be involved in the uptake of alpha-tocopherol from the plasma. To understand the role of the uptake system we have compared the alpha-tocopherol content and binding activity of red blood cells from smokers and non-smokers. The specific binding of [3H] alpha-tocopherol to pure red blood cell preparations from smokers (n = 7, 28.4 +/- 2.8 years) was 30.6 +/- 3.2 fmoles per 3 x 10(8) red blood cells and for non-smokers (n = 17, 27.9 +/- 1.3 years) was 41.7 +/- 3.7 fmoles per 3 x 10(8) red blood cells. Thus alpha-tocopherol uptake activity was significantly lower in smokers (P = 0.05). Red blood cells from smokers contained less (1.8 +/- 0.4 micrograms/gHb) alpha-tocopherol than non-smokers (2.8 +/- 0.3 micrograms/gHb), (P < 0.05), despite plasma levels of alpha-tocopherol being similar: 12.9 +/- 0.8 microM in non-smokers vs. 12.7 +/- 0.5 microM in smokers. However, adjusting plasma alpha-tocopherol for total plasma cholesterol plus triacylglycerols showed alpha-tocopherol levels were higher (P < 0.01) in non-smokers (2.84 +/- 0.10 mumol alpha-tocopherol/ mmol [cholesterol+triacylglycerol]) than in smokers (2.36 +/- 0.11 mumol alpha-tocopherol/mmol [cholesterol+triacylglycerol]). The reduced alpha-tocopherol levels in red blood cells from smokers may be due to impairment of alpha-tocopherol uptake activity. The reduced levels of alpha-tocopherol in smokers red blood cells was not associated with any changes in cell membrane fluidity. At present it is not known whether supplementation of smokers with vitamin E would normalise the alpha-tocopherol uptake activity of red blood cells.

High D-glucose does not affect binding of alpha-tocopherol to human erythrocytes.

The role of alpha-tocopherol uptake system in human erythrocyte in the uptake of plasma alpha-tocopherol has been suggested. However no information is available on alpha-tocopherol uptake activity of human erythrocytes in the presence of high levels of D-glucose which is known to lead to pathological alterations in different cells including human erythrocytes. Therefore, in order to examine the effect of D-glucose on the binding of alpha-tocopherol to human erythrocytes, the binding characteristics of alpha-tocopherol to these cells were established first. Binding of [3H]alpha-tocopherol to human erythrocytes was both saturable and specific. Scatchard analysis of alpha-tocopherol binding to these cells showed the presence of two independent classes of binding sites with widely different affinities. The high affinity binding sites had a dissociation constant (Kd1) of 90 nM with a binding capacity (n1) of 900 sites per cell, whereas the low affinity binding sites had a dissociation constant (Kd2) of 5.2 microM and a binding capacity (n2) of 105,400 sites per cell. Trypsin treatment abolished all the alpha-tocopherol binding activity. Competition for the binding of alpha-tocopherol to human erythrocytes was effective with other homologues of alpha-tocopherol (beta-tocopherol, gamma-tocopherol and delta-tocopherol) and their potency was almost equal to alpha-tocopherol itself. The order of preference was alpha-tocopherol > beta-tocopherol > or = gamma-tocopherol > or = delta-tocopherol. Incubation of human erythrocytes with various concentrations of D-glucose did not affect alpha-tocopherol uptake activity. Our data demonstrate the presence of an alpha-tocopherol uptake system in human erythrocytes and that the alpha-tocopherol uptake activity is not modulated by the presence of D-glucose.

Vitamin E and coronary heart disease: the European paradox.

OBJECTIVE: To relate premature mortality from coronary heart disease (CHD) to national food and nutrient supplies. DESIGN: Descriptive correlational study. SETTING: Nineteen western European and five non-European countries. METHODS: Premature mortality from CHD in men below 65 years was related to recalculated Food and Agriculture Organization (FAO) food, antioxidant vitamins and other nutrient supply data in 24 developed countries for 1985-87. Longitudinal analyses of death rates from CHD and supplies between 1970 and 1987 were carried out for all the countries. Correlational analyses of supplies that preceded mortality by up to 10 years were also undertaken. RESULTS: In 17 western European countries the inter-country association of dairy product supply with CHD was of moderate strength (r = 0.5) and the principal saturated fatty acids derived from dairy products: butyric, caproic and myristic acids (C4:0, C6:0 and C14:0) were the most strongly related with CHD (r = 0.5, 0.5 and 0.4 respectively). The phenolic-antioxidant-rich foods, e.g. wine, vegetables and vegetable oils, were inversely related to CHD (r = -0.8, -0.7 and -0.6 respectively). Of the antioxidant vitamins, the alpha-tocopherol component of vitamin E was strongly related to CHD across Europe (r = -0.8). The major determinant of alpha-tocopherol supply was usually sunflowerseed oil. Vitamin C and beta-carotene gave moderate correlations (r = -0.6 and -0.5 respectively). Latency periods of 5 and 10 years between supplies and mortality rates did not markedly change the correlations. Longitudinal analyses of nutrient supplies and death rates within each country from 1970 to 1987 also showed that for the majority of countries there was an inverse association between supply of alpha-tocopherol and CHD. CONCLUSIONS: Dietary alpha-tocopherol may provide at least as good an explanation as does wine for the paradoxically low rates of CHD in several European countries which have a relatively high saturated fatty acid intake.