Sophie S.F. Leung

Effects of Diet and Exercise on Obesity-Related Vascular Dysfunction in Children

Background—The prevalence of obesity in both adults and children is increasing rapidly. Obesity in children is independently associated with arterial endothelial dysfunction and wall thickening, key early events in atherogenesis that precede plaque formation. Methods and Results—To evaluate the reversibility of obesity-related arterial dysfunction and carotid intima-media thickening by dietary and/or exercise intervention programs, 82 overweight children (body mass index, 25±3), 9 to 12 years of age, were randomly assigned to dietary modification only or diet plus a supervised structured exercise program for 6 weeks and subsequently for 1 year. The prospectively defined primary end points were ultrasound-derived arterial endothelial function (endothelium-dependent dilation) of the brachial artery and intima-media thickness of common carotid artery. At 6 weeks, both interventions were associated with decreased waist-hip ratio (P <0.02) and cholesterol level (P <0.05) as well as improved arterial endothelial function. Diet and exercise together were associated with a significantly greater improvement in endothelial function than diet alone (P =0.01). At 1 year, there was significantly less thickening of the carotid wall (P <0.001) as well as persistent improvements in body fat content and lipid profiles in the group continuing an exercise program. Vascular function was significantly better in those children continuing exercise (n=22) compared with children who withdrew from the exercise program (n=19) (P <0.05). Conclusions—Obesity-related vascular dysfunction in otherwise healthy young children is partially reversible with diet alone or particularly diet combined with exercise training at 6 weeks, with sustained improvements at 1 year in those persisting with diet plus regular exercise.

Overweight in children is associated with arterial endothelial dysfunction and intima-media thickening.

OBJECTIVE: We sought to study arterial endothelial function and carotid intima-media thickness (IMT), both early markers of atherosclerosis, in overweight compared to normal children.DESIGN: Case–control comparison.SUBJECTS: A total of 36 asymptomatic overweight children (body mass index (BMI)>23; mean 25±3) aged 9–12u2009y and 36 age- and gender-matched nonobese healthy children (BMI<21) from a school community.MEASUREMENTS: The key parameters were: BMI, arterial endothelial function (ultrasound-derived endothelium-dependent dilation) and carotid artery IMT. The secondary parameters measured included body fat content, waist–hip ratio (WHR), blood pressures, blood lipids, insulin and glucose.RESULTS: The two groups were well matched for blood pressures, cholesterol and glucose levels, but BMI (P<0.0001), body fat (P=0.001), WHR (P<0.05), fasting blood insulin (P=0.001) and triglyceride levels (P<0.05) were higher in obese children. Overweight was associated with impaired arterial endothelial function (6.6±2.3 vs 9.7±3.0%, P<0.0001) and increased carotid IMT (0.49±0.04u2009mm vs 0.45±0.04u2009mm, P=0.006). The degree of endothelial dysfunction correlated with BMI (P<0.003) on multivariate analysis.CONCLUSION: Obesity, even of mild-to-moderate degree, is independently associated with abnormal arterial function and structure in otherwise healthy young children.

Association between simple anthropometric indices and cardiovascular risk factors.

OBJECTIVE: To identify which of the three simple anthropometric indices, body mass index (BMI), waist-to-hip ratio (WHR) and waist circumference (WC), best predicts cardiovascular risk factors, and to determine if the association between the anthropometric indices and cardiovascular risk factors varies with gender.DESIGN AND METHODOLOGY: A cross-sectional population-based survey was carried out during 1995–1996. One thousand and ten Chinese people (500 men and 510 women) aged 25–74u2005y were recruited as subjects for the study. Metabolic profiles and anthropometric indices were measured.RESULTS: Partial correlation and co-variance analyses showed that WC exhibited the highest degree of association with almost all of the studied metabolic profiles for both men and women. We observed significant gender differences in the association between central or general obesity with cardiovascular risk factors. BMI had an independent and significant association with metabolic risks in men, but not in women, whereas WHR was more strongly correlated with metabolic risks for women than for men. Logistic regression analysis further confirmed the magnitude of the association between the obesity indices and metabolic risks. Among the studied metabolic variables, serum insulin showed the highest degree of association with the obesity indices, followed by plasma glucose, triglyceride, HDL and blood pressure. Total cholesterol and LDL-cholesterol had a small but significant correlation with obesity. No threshold values in the relation between either the anthropometric indices and metabolic values, or with hypertension, diabetes and dislipidemia were observed.CONCLUSION: The association of central or general obesity and metabolic syndrome varied with gender. In addition, the useful anthropometric predictors for cardiovascular risk factors were BMI and WC for men, and WC and WHR for women.

A randomized double-blind controlled calcium supplementation trial, and bone height acquisition in children

There is limited information relating Ca intake to bone and height acquisition among Oriental children who consume little or even no milk. The present controlled study investigated the acquisition of bone mass and height of Chinese children with an initial Ca intake of approximately 567 mg/d who were supplemented to about 800 mg/d. Eighty-four 7-year-old Hong Kong Chinese children underwent an 18-month randomized, double-blind, controlled Ca-supplementation trial. The children were randomized to receive either 300 mg elemental Ca or a placebo tablet daily. Bone mass of the distal one-third radius was measured by single-photon absorptiometry, lumbar spine and femoral neck were determined using dual-energy X-ray absorptiometry. Measurements were repeated 6-monthly. Baseline serum 25-hydroxycholecalciferol concentration and physical activity were also assessed. Baseline Ca intakes of the study group and controls were respectively 571 (SD 326) and 563 (SD 337) mg/d. There were no significant differences in baseline serum 25-hydroxycholecalciferol concentration (P = 0.71) and physical activity (P = 0.36) between the study and control groups. After 18 months the study group had significantly greater increases in lumbar-spinal bone mineral content (20.9 v. 16.34%; P = 0.035), lumbar-spinal area (11.16 v. 8.71%; P = 0.049), and a moderately greater increment in areal bone mineral density of the radius (7.74 v. 6.00%; P = 0.081) when compared with the controls. The results confirm a positive effect of Ca on bone mass of the spine and radius but no effects on femoral-neck and height increase. A longer trial is warranted to confirm a positive Ca effect during childhood that may modify future peak bone mass.

A food frequency questionnaire for use in the chinese population in hong kong: Description and examination of validity

Abstract A food frequency questionnaire consisting of seven categories of food types and 266 food items was developed for a dietary survey of the Hong Kong Chinese population. The quantity, frequency of consumption per day and per week for each item was recorded with the aid of photographs to illustrate portion sizes, and nutrient quantity calculated using Food Tables from multiple sources — UK and two mainland Chinese institutions. The validity of the nutrient quantitation was examined by comparing calculated 24 hour intake of total energy, sodium, and potassium, with estimated values of energy expenditure (BMR × 1.4), 24h urinary sodium and potassium outputs. Apart from probable underestimation of sodium and potassium intake, calculated values for energy were close to estimated values. Associations were also present between energy intake, cholesterol, fat, and fatty acid intakes, and serum lipid profile. It is concluded that this questionnaire is suitable for dietary surveys in Hong Kong Chinese and may be used for quantitation of nutrient intakes in studies examining dietary components as risk factors.

Influence of educational level and marital status on dietary intake, obesity and other cardiovascular risk factors in a Hong Kong Chinese population

Objectives: To examine the influence of education and marital status on dietary intake, body mass index, waist hip ratio, blood pressure, fasting and 2u2005h glucose, and lipid profile in adult Hong Kong Chinese.Design: Randomized age and sex stratified surverySubjects: One thousand and ten subjects aged 25–74u2005y (500 men, 510 women) recruited for the 1995–96 Hong Kong Dietary and Cardiovascular Risk Prevalence Survey.Measurements: Dietary intake was estimated using a food frequency method. Information on education level and marital status was included in the questionnaire. Anthropometry and biochemical parameters were measured using standard methods.Results: After adjustment for age, higher levels of education are associated with higher percentage protein intake in men, higher percentage fat intake in women, higher nutrient density of fibre and calcium in both men and women, and higher nutrient density of protein, fat, niacin, vitamin D, and polyunsaturated fatty acid in women. Consumption of fruits was also higher in women, and that of dairy products higher in men. Body mass index and waist-hip ratio were lower with increasing levels of education in women, while lower mean systolic BP was observed in men. Single women had lower nutrient densities of vitamin D and iron, and lower consumption of vegetables and fish, compared with married women. Body mass index was lower in both single men and women. Single men had a better cardiovascular risk factor profile, in that diastolic BP, triglycerides and cholesterol/HDL ratio were lower, in addition to a lower body mass index.Conclusion: Higher education level is associated with a healthier diet and lower prevalence of overweight.Sponsorship: Hong Kong Health Services Research Grant.

Relationship between long-term calcium intake and bone mineral content of children aged from birth to 5 years

This study evaluated Ca intake in Hong Kong Chinese children and examined the association between long-term Ca intake and bone mineral content (BMC) in children. Longitudinal dietary intake from birth to 5 years was obtained in 128 children (sixty-seven boys, sixty-one girls). Ca intakes were evaluated by dietary history and cross-checked with food frequency and 24 h recall. At age 5 years BMC was determined at the one-third distal radius of the right arm using single-photon absorptiometry. The mean Ca intake of 133 children at 5 years was 546 (SD 325) mg/d. Milk was the chief source of Ca (43.5%). From birth to 5 years, 90% of the children had been taking milk regularly. The mean BMC and bone width (BW) of these children were 0.317 (SD 0.042) g/cm and 0.756 (SD 0.074) cm respectively. BMC was not correlated with current intakes of Ca, energy and protein but was positively correlated with weight (r 0.57), height (r 0.47) and BW (r 0.66). However, cumulative Ca intake throughout the past 5 years showed significant correlation with BMC (r 0.235, P = 0.0133). The significant correlation remained even after weight, height, BW, sex, and cumulative intakes of energy and protein were adjusted in multiple regression analysis (r 0.248, P = 0.0107). Moreover, using principal component analysis, Ca intake during the 2nd year of life had the strongest correlation with BMC at 5 years (r 0.240, P = 0.02). Ca intake of Hong Kong Chinese children was higher than the RDA of the Food and Agriculture Organization/World Health Organization (1962) and achieved 66% of the current US recommendation (National Research Council, 1989). The increased regular milk consumption reflects a significant change in dietary habits of the younger generation. Children with a habitually higher Ca intake throughout the past 5 years, particularly in the 2nd year, were found to have higher BMC.

Dietary intake and practices in the Hong Kong Chinese population.

OBJECTIVES: To examine dietary intake and practices of the adult Hong Kong Chinese population to provide a basis for future public health recommendations with regard to prevention of certain chronic diseases such as cardiovascular disease, hypertension, and osteoporosis. PARTICIPANTS: Age and sex stratified random sample of the Hong Kong Chinese population aged 25 to 74 years (500 men, 510 women). METHOD: A food frequency method over a one week period was used for nutrient quantification, and a separate questionnaire was used for assessment of dietary habits. Information was obtained by interview. RESULTS: Men had higher intakes of energy and higher nutrient density of vitamin D, monounsaturated fatty acids and cholesterol, but lower nutrient density of protein, many vitamins, calcium, iron, copper, and polyunsaturated fatty acids. There was an age related decrease in energy intake and other nutrients except for vitamin C, sodium, potassium, and percentage of total calorie from carbohydrate, which all increased with age. Approximately 50% of the population had a cholesterol intake of < or = 300 mg; 60% had a fat intake < or = 30% of total energy; and 85% had a percentage of energy from saturated fats < or = 10%; criteria considered desirable for cardiovascular health. Seventy eight per cent of the population had sodium intake values in the range shown to be associated with the age related rise in blood pressure with age. Mean calcium intake was lower than the FAO/WHO recommendations. The awareness of the value of wholemeal bread and polyunsaturated fat spreads was lower in this population compared with that in Australia. There was a marked difference in types of cooking oil compared with Singaporeans, the latter using more coconut/palm/mixed vegetable oils. CONCLUSION: Although the current intake pattern for cardiovascular health for fat, saturated fatty acid, and cholesterol fall within the recommended range for over 50% of the population, follow up surveys to monitor the pattern would be needed. Decreasing salt consumption, increasing calcium intake, and increasing the awareness of the health value of fibre may all be beneficial in the context of chronic disease prevention.

Bone mineral content of two populations of Chinese children with different calcium intakes

Bone mineral content (BMC) of 5-year-old Chinese children (115 children in Jiangmen, China and 128 children in Hong Kong) was evaluated by single-photon absorptiometry at the distal 1/3 radius. The mean (S.D.) calcium intakes of children of Jiangmen and Hong Kong were 244 (46) and 542 (332) mg/day, respectively. The mean BMC, weight and height of Jiangmen children were significantly less than Hong Kong children by 14%, 10% and 4%, respectively (P < 0.001). Multiple regression analysis showed that 62% of the variance in BMC was explained by bone width (BW), weight and regional location (P < 0.0001). A regional difference in BMC of 0.0303 g/cm (P < 0.0001) still remained after adjusting for BW and weight by multiple regression analysis. When comparing sub-groups of children in the two regions with comparable low current calcium intake at 5 years, the BMC of Jiangmen children was still significantly lower than Hong Kong children even when potential confounders were adjusted (P < 0.003). The study suggests that the regional discrepancy in BMC might be explained by long-term habitual calcium intake and physical activity.

The Mediterranean score of dietary habits in Chinese populations in four different geographical areas.

Objective: To compare the dietary intake of Chinese people living in Pan Yu, Hong Kong, San Francisco and Sydney with respect to cardiovascular health, using the Mediterranean diet score, examining the effects of age, gender, urbanization and acculturation on the diet score.Subjects: A total of 500 men and 510 women in Hong Kong were recruited as a territory-wide stratified random sample. Subjects were recruited in response to local advertisements for the other three sites: Pan Yu, 58 men, 95 women; San Francisco, 166 men, 192 women; Sydney, 95 men, 73 women.Method: Food-frequency questionnaire over a 7 week period. A high/healthy score was taken as ≥4 for men and ≥3 for women, representing a dietary pattern beneficial for cardiovascular health.Results: In Hong Kong, more women in the middle age group (35–54) had a high score than other age groups, and overall more women had high scores than men. In comparing the four geographical regions, Pan Yu had the highest number of subjects with high score, and Hong Kong had the lowest. With the exception of the younger population and men in Hong Kong, the percentage of the population with a high score in all sites is greater than among elderly Greeks consuming a more traditional heart-healthy Mediterranean diet.Conclusion: Considerable variations in Chinese dietary patterns exist with respect to age, gender and geographic location. Overall, the Chinese diet is comparable to the Mediterranean diet and may be expected to have similar health benefits that have been documented for the traditional Mediterranean diet.European Journal of Clinical Nutrition (2001) 55, 215–220