Estimation of Iron Physiological Requirement in Chinese Children using Single Stable Isotope Tracer Technique.

Objective: This study is to obtain precise data on iron physiological requirements in Chinese children using single stable isotope tracer technique. Methods: Thirty boys (10.6 ± 0.2 years) and 27 girls (10.4 ± 0.2 years) were received oral 6 mg 57Fe each day for 5 consecutive days. Venous blood samples were subsequently drawn to examine the change of total iron concentration and 57Fe abundance at day 0, 14, 28, 60, 90, 180, 360, 450, 540, 630, 720. The iron physiological requirement was calculated by iron loss combined with iron circulation rate once 57Fe abundance stabilized in human body. Results: The iron physiological requirement was significantly lower in boys than those values in girls (16.88 ± 7.12 vs. 18.40 ± 8.81 µg/kg per day, P < 0.05). Correspondingly, the values were calculated as 722.46 ± 8.43 µg/day for boys and 708.40 ± 7.55 µg/day for girls, respectively. Considering nearly 10% iron absorption rate, the estimated average iron physiological requirement was 6.0 mg/day in boys and 6.2 mg/day in girls. Conclusion: This study indicate that iron physiological requirement could require more daily iron intake in girls as compare with the values in boys having the same body weight. These findings would be facilitate to the new revised dietary reference intakes.

Basal Energy Expenditure of Chinese Healthy Adults: Comparison of Measured and Predicted Values.

OBJECTIVE: This study aimed to measure the basal energy expenditure (BEE) of Chinese healthy adults and establish an accurate predictive equation for this population. METHODS: In total, 470 Chinese healthy adults had their BEE measured using the Cosmed K4b 2 portable metabolic system. Multiple linear regression analysis was applied to develop new optimal equations for predicting BEE. The bias, accuracy rate, concordance correlation coefficient (CCC), and root mean square error (RMSE) were used to evaluate the accuracy of the predictive equations. RESULTS: There was a significant difference in BEE between males and females, with 5,954 kJ/d and 5,089 kJ/d, respectively. People living in rural areas expended significantly higher BEE (5,885 kJ/d) than those in urban areas (5,279 kJ/d). Previous equations developed by Henry, Schofield, Harris-Benedict (H-B), and Liu overestimated the BEE of Chinese healthy adults. The new equations derived from the present study displayed the smallest average bias and RMSE from the measured basal energy expenditure (mBEE). The CCC of the new equations was higher than other predictive equations, but it was lower than 0.8. There was no significant difference in the accuracy rate among all predictive equations. CONCLUSIONS: Sex and regional differences in BEE were observed in Chinese healthy adults. Neither the widely used previous predictive equations nor the one derived in the present study were accurate enough for estimating the BEE of Chinese healthy adults. Further study is required to develop more accurate equations for predicting the BEE of Chinese healthy adults aged between 20-45 years.

Distribution of High-sensitivity C-reactive Protein Status in an Urban Population in China.

OBJECTIVES: To evaluate the distribution by age and sex of serum high-sensitivity C-reactive protein (hsCRP) in an urban Chinese population and to provide a profile prediction for the risk of bacterial infection, inflammatory diseases, or tissue damages in the body. METHODS: Serum hsCRP was determined using the Roche Tina-quant immuno-turbidimetric assay on a Hitachi 7600-010 automatic biochemical analyzer (Roche Diagnostics) in 1,572 males and 1,800 females, including 78 pregnant women, who were derived from the National Health and Nutrition Survey in 2010-2012. RESULTS: The average hsCRP concentration in urban China was 0.68 mg/L for males and 0.65 mg/L for females. Significant differences in hsCRP were found among different age groups ( P < 0.05). Monitoring results showed no significant differences among the 6-11, 45-59, and ≥ 60-year-old groups in the comparison of hsCRP between males and females in large cities. However, hsCRP concentration was significantly higher in men aged 12-17 and 18-44 years than in women. CONCLUSION: The distribution of the hsCRP status of residents in large cities in China was influenced by age and gender, and the hsCRP levels of both sexes increased gradually with age. In addition, hsCRP concentration was higher in healthy pregnant women than in non-pregnant women. Basing on our results, we recommend that this parameter be included in future national and international screening for early detection of various illnesses.

Evaluation of Erythrocyte Iron Incorporation in Beijing Prepubertal Children Using a Single Stable Isotope Tracer Method.

OBJECTIVE: To analyze the rate of erythrocyte iron incorporation and provided guidance for the iron nutrition for prepubertal children. METHODS: Fifty-seven prepubertal children of Beijing were involved in this study and each subject was orally administered 3 mg of 57Fe twice daily to obtain a total of 30 mg 57Fe after a 5-d period. The stable isotope ratios in RBCs were determined in 14th day, 28th day, 60th day, and 90th day. The erythrocyte incorporation rate in children was calculated using the stable isotope ratios, blood volume and body iron mass. RESULTS: The percentage of erythrocyte 57Fe incorporation increased starting 14 th day, reached a peak at 60 d (boys: 19.67% ± 0.56%, girls: 21.33% ± 0.59%) and then decreased. The erythrocyte incorporation rates of 57Fe obtained for girls in 60th day was significantly higher than those obtained for boys ( P < 0.0001). CONCLUSIONS: The oral administration of 57Fe to children can be used to obtain erythrocyte iron incorporation within 90 d. Prepubertal girls should begin to increase the intake of iron and further studies should pay more attention to the iron status in prepubertal children.

Zinc Absorption from Representative Diet in a Chinese Elderly Population Using Stable Isotope Technique.

OBJECTIVE: To determine the dietary zinc absorption in a Chinese elderly population and provide the basic data for the setting of zinc (Zn) recommended nutrient intakes (RNI) for Chinese elderly people. METHODS: A total of 24 elderly people were recruited for this study and were administered oral doses of 3 mg 67Zn and 1.2 mg dysprosium on the fourth day. The primary macronutrients, energy, and phytic acid in the representative diet were examined based on the Chinese National Standard Methods. Fecal samples were collected during the experimental period and analyzed for zinc content, 67Zn isotope ratio, and dysprosium content. RESULTS: The mean (± SD) zinc intake from the representative Chinese diet was 10.6 ± 1.5 mg/d. The phytic acid-to-zinc molar ratio in the diet was 6.4. The absorption rate of 67Zn was 27.9% ± 9.2%. The RNI of zinc, which were calculated by the absorption rate in elderly men and women, were 10.4 and 9.2 mg/d, respectively. CONCLUSION: This study got the dietary Zn absorption in a Chinese elderly population. We found that Zn absorption was higher in elderly men than in elderly women. The current RNI in elderly female is lower than our finding, which indicates that more attention is needed regarding elderly females' zinc status and health.

Protein requirements in healthy adults: a meta-analysis of nitrogen balance studies.

OBJECTIVE: The goal of this study was to analyze protein requirements in healthy adults through a meta-analysis of nitrogen balance studies. METHODS: A comprehensive search for nitrogen balance studies of healthy adults published up to October 2012 was performed, each study were reviewed, and data were abstracted. The studies were first evaluated for heterogeneity. The average protein requirements were analyzed by using the individual data of each included studies. Study site climate, age, sex, and dietary protein source were compared. RESULTS: Data for 348 subjects were gathered from 28 nitrogen balance studies. The natural logarithm of requirement for 348 individuals had a normal distribution with a mean of 4.66. The estimated average requirement was the exponentiation of the mean of the log requirement, 105.64 mg N/kg•d. No significant differences between adult age, source of dietary protein were observed. But there was significant difference between sex and the climate of the study site (P<0.05). CONCLUSION: The estimated average requirement and recommended nutrient intake of the healthy adult population was 105.64 mg N/kg•d (0.66 g high quality protein/kg•d) and 132.05 mg N/kg•d (0.83 g high quality protein/kg•d), respectively.

Evaluation of the protein requirement in Chinese young adults using the indicator amino acid oxidation technique.

OBJECTIVE: To accurately calculate the protein requirements in Chinese young adults using the indicator amino acid oxidation technique. METHODS: Nine women and ten men received a restricted daily level of protein intake (0.75, 0.82, 0.89, 0.97, and 1.05 g/kg), along with L-[1-13C]-leucine. Subjects' protein requirement was determined by a biphasic linear regression crossover analysis of F13CO2 data. In doing so, a breakpoint at the minimal rate of appearance of 13CO2 expiration specific to each level of dietary protein was identified. This trial was registered with the Chinese clinical trial registry as ChiCTR-ONC-11001407. RESULTS: The Estimated Average Requirement (EAR) and the Recommended Nutrient Intake (RNI) of protein for healthy Chinese young adults were determined to be 0.87 and 0.98 g/(kg•d), respectively, based on the indicator amino acid oxidation technique. CONCLUSION: The EAR and RNI of mixed protein are 5% and 16% that are lower than the current proposed EAR and RNI (0.92 and 1.16 g/(kg•d), respectively), as determined by the nitrogen balance method. The respective EAR and RNI recommendations of 0.87 and 0.98 g/(kg•d) of mixed protein are estimated to be reasonable and suitable for Chinese young adults.

Total energy expenditure of 16 Chinese young men measured by the doubly labeled water method.

OBJECTIVE: Doubly labeled water (DLW) method is the gold standard for measuring total energy expenditure (TEE). We used this method to measure TEE in Chinese young men. METHODS: Sixteen healthy young men age 23±1 years with body mass index 22.0±1.4 kg/m2 were recruited. TEE was measured by the DLW method, and basal energy expenditure (BEE) was determined by indirect calorimetry. We also conducted 24-h activity, energy balance and factorial approach to estimate energy requirements of the subjects. RESULTS: TEE of subjects by DLW method was 9.45±0.57 MJ/day (2258±180 kcal/day). The 24-h activity was 10.80±0.33 MJ/day (2582±136 kcal/day). The energy requirement, derived from energy balance observations, was 9.93±1.32 MJ/day (2373±315 kcal/day). The BEE of 6.65±0.28 MJ/day (1589±67 kcal/day), calculated by the adjusted Schofield equation, was significantly higher (P<0.001) than that measured by indirect calorimetry, 5.99±0.66 MJ/day (1433±158 kcal/day). The TEE derived from the factorial approach was 10.31±0.43 MJ/day (2463±104 kcal/day). CONCLUSION: The TEE of Chinese young men measured by the DLW method was about 10% lower than the current recommended nutrient intake (RNI), suggesting that the RNI for Chinese men maybe overestimated. Further studies are warranted to determine the value of the estimated energy requirement.

[The main nutrients digestibility of genetically modified rice and parental rice in the terminal ileum of pigs].

OBJECTIVE: To compare the digestibility of main nutrients in genetically modified rice with double antisense starch-branching enzyme gene and parental rice. METHODS: Seven Wuzhishan healthy adult barrows were surgically fitted with a T-cannula at the terminal ileum. After surgery, seven pigs were randomly divided into two groups, and fed genetically modified rice and parental rice by a crossover model. Ileal digesta were collected for analysis of main nutrient digestibility. RESULTS: The apparent digestibility levels of protein in genetically modified rice and parental rice were 69.50% ± 4.50%, 69.61% ± 8.40%, respectively (t = 0.01, P = 0.994); true digestibility levels of protein were 87.55% ± 4.95%, 87.64% ± 9.40%, respectively (t = 0.01, P = 0.994); fat digestibility levels were 72.86% ± 0.34%, 77.89% ± 13.09%, respectively (t = 0.95, P = 0.378); carbohydrate digestibility levels were 72.92% ± 7.43%, 92.35% ± 5.88%, respectively (t = 4.27, P = 0.005). The apparent and true digestibility of 17 amino acids had no significant difference in the two rice. CONCLUSION: Carbohydrate digestibility in genetically modified rice was significantly lower than that in non-genetically modified rice, other main nutrients digestibility in the two rice have substantial equivalence.

Dietary energy requirements of young adult women in China by the doubly labeled water method.

OBJECTIVE: The current recommendations on dietary energy requirements in China have been based on total energy expenditure (TEE) derived from theoretical factorial calculations expressed as multiples of basal energy expenditure (BEE). Few direct measurements of TEE and BEE have been conducted in Chinese people. This study was designed to measure the TEE and BEE of healthy, light active women of normal body weight living in China, and to evaluate the recommendations on dietary energy requirements by comparing the data correspondingly. DESIGN: 16 healthy female adults aged 22.1 ± 1.2 y with a body mass index (in kg/m2) of 20.4 ± 1.7 were selected. Under well-controlled conditions, TEEs were determined by using the doubly labeled water method. At the same time, BEEs were measured by using indirect calorimetry. RESULTS: Measured TEE was 1380 ± 118 kcal/d, which was close to the value of energy intake (1382 ± 96 kcal/d). Comparing the measured TEE with the recommended (Chinese recommended value for this group is 2100 kcal/d), the recommended was substantially higher than the measured by 15% or so. Meanwhile, the calculated BEE (1230 ± 65 kcal/d) by using the adjusted Schofield equation proposed by the Chinese Nutrition Society was significantly higher (p < 0.001) than the measured BEE (1130 ± 110 kcal/d), by 9% or so. CONCLUSION: Current recommended energy intake for young adult women may need to be revised on the basis of measured TEE and BEE.

[Comparative study of the pulmonary function equipment and Douglas-bag in the energy consumption measurement of Chinese healthy youth].

OBJECTIVE: To determine the validity of the pulmonary function equipment. METHODS: 12 young students (including six males and six females) were enrolled as our research subjects. And the values of oxygen consumption (VO(2)), carbon dioxide production (VCO(2)) and energy expenditures (EE) of the subjects under three typical activity intensities: resting, moderate intensity (on a treadmill with grade 10% and speed 2.7 km/h) and hard intensity (on a treadmill with grade 10% and speed 5.8 km/h) were measured using the pulmonary function equipment (K4b(2)) and Douglas-bag respectively. And the Douglas-bag method was used as reference and the results were compared with the other method. RESULTS: The measured VO(2) values by using the Douglas-bag and the pulmonary function equipment under three typical activity intensities were: at rest (0.22 ± 0.03), (0.22 ± 0.05) L/min (t = 0.120, P > 0.05); moderate intensity condition (0.95 ± 0.12), (0.96 ± 0.14) L/min (t = 0.240, P > 0.05); hard intensity condition (1.63 ± 0.28), (1.54 ± 0.35) L/min (t = 1.487, P > 0.05). For VCO(2) values: at rest (0.18 ± 0.02), (0.18 ± 0.04) L/min (t = 0.425, P > 0.05); moderate intensity (0.82 ± 0.11), (0.83 ± 0.13) L/min (t = 0.579, P > 0.05); hard intensity (1.64 ± 0.27), (1.52 ± 0.39) L/min (t = 2.330, P < 0.05). And for EE values, at rest (269.40 ± 35.70), (267.02 ± 55.39) kJ/h (t = 0.200, P > 0.05); moderate intensity (1165.76 ± 148.06), (1185.91 ± 161.89) kJ/h (t = 0.326, P > 0.05); hard intensity (2062.91 ± 341.97), (1912.27 ± 483.88) kJ/h (t = 1.718, P > 0.05) respectively. The results showed that there were no significant differences between the two methods except the VCO(2) values under high intensity condition was underestimated by the pulmonary function equipment. Bland-Altman test showed that the difference of the two methods was evenly distributed by the mean and standard error of the system was 24.7 kJ/h. Our data showed the results from the Douglas-bag and the pulmonary function equipment were consistent. CONCLUSION: Pulmonary function equipment had good validity in assessing the energy expenditure in Chinese adults.

Relatively high bone mineral density in Chinese adolescent dancers despite lower energy intake and menstrual disorder.

OBJECTIVE: The effect of dietary restriction, intense exercise and menstrual dysfunction on bone mineral density remains controversial. The aim of this study was to assess the skeletal health status and relationship between bone mineral density and nutrient intake, menstrual status, estrogen level and other factos in Chinese adolescent dancers. METHODS: Sixty dancers and 77 healthy controls underwent measurements of bone density, body composition, and estrogen level. Nutrient intake, menstrual status and physical activity were assessed with questionnaires. The correlation between these factors were analyzed. RESULTS: The dancers under study had a significantly lean body mass index (18.3 +/- 1.4 kg/m2 vs. 21.7 +/- 3.1 kg/m2), lower percentage of body fat (0.25 +/- 0.05 vs. 0.34 +/- 0.04) and later age at menarche (14.0 +/- 0.9 y vs. 13.0 +/- 1.3 y), and the estrogen level, daily calorie and fat intake in them were also lower than in the controls. All the dancers undertook intensive physical activity every day and up to 69% of them suffered from irregular menarche. Yet they had relatively high BMD and BMC of the total body and legs than the controls after adjusting for BMI and age. Site-specific BMD was positively correlated to BMI, body composition and training hours per week and negatively correlated to the age at menarche and menstrual frequency. CONCLUSIONS: The relatively high BMD and BMC of the dancers at the total body and legs were probably caused by high levels of weight-bearing physical activity. To ameliorate disordered eating, especially low energy intake might be helpful to prevent the Triad and to improve the bone health in adolescent dancers.

Association between adiponectin and metabolic syndrome in older adults from major cities of China.

OBJECTIVE: To investigate the association between adiponectin and metabolic syndrome (MetS) and related diseases in older adults from major cities of China. METHODS: A total of 2 049 adults at the age of 60-96 years from 18 major cities of China were enrolled in the study. Plasma adiponectin and insulin concentrations were measured. Insulin resistance was assessed by homeostasis model assessment of insulin resistance (HOMA-IR). The definitions proposed by International Diabetes Federation (IDF) and American Heart Association/National Heart, Lung, and Blood Institute (AHA/NLHBI) were used to identify MetS. RESULTS: The adiponectin concentration increased with the advance of age and was higher in women than in men. The sex specific adiponectin concentration was inversely correlated with body mass index (BMI), waist circumference, diastolic blood pressure, triglycerides, glucose and fasting blood insulin, and positively correlated with HDL-C (P < 0.001). The adiponectin concentration decreased with increasing MetS components. Compared with the 4th sex-specific adiponectin quartile, the odds ratio (OR) for prevalent MetS-IDF and MetS-AHA/NLHBI in subjects of the 1st quartile group was 3.25 (95% CI: 2.24, 4.71) and 3.21 (95% CI: 2.26, 4.55), respectively. The association was independent of age, sex, life-style factors, medication, family history of chronic diseases, BMI, and HOMA-IR. The OR for MetS was much higher than those of MetS components and its related diseases. CONCLUSION: Adiponectin is strongly associated with MetS independent of insulin resistance and obesity in older adults from major cities in China. The adiponectin concentration is a useful predictor for the risk of MetS.

Postprandial glycaemic and insulinaemic responses to GM-resistant starch-enriched rice and the production of fermentation-related H2 in healthy Chinese adults.

Consumption of resistant starch (RS)-enriched foods is associated with decrease in the postprandial glycaemic and insulinaemic responses, accompanied by the production of fermentation-related gases in the large bowel. The present study aimed to determine the postprandial glycaemic and insulinaemic responses to the GM RS-enriched rice and the fermentation-related production of H2 in young and healthy Chinese adults. A total of sixteen young adults (nine men and seven women) were recruited and divided into three groups. Their postprandial glycaemic and insulinaemic responses to 40 g glucose, carbohydrates of RS or wild-type (WT) rice were tested by a crossover model with a washout period of 7 d. The concentrations of blood glucose and insulin as well as breath H2 were measured before and after food intake. Although the mean concentrations of fasting blood glucose, insulin and breath H2 were similar, consumption of the RS rice significantly decreased the values of glycaemic index (GI) and insulin index (II), as compared with the intake of WT rice (48.4 (sem 21.8) v. 77.4 (sem 34.9) for GI, 34.2 (sem 18.9) v. 54.4 (sem 22.4) for II, P < 0.05), respectively. Conversely, intake of the RS rice meal significantly elevated the concentrations of breath H2, as compared with WT rice (38.9 (sem 17.6) v. 10.5 (sem 3.7) parts per million for peak levels of breath H2, P < 0.05) through a period of 16-h tests. Consumption of the GM RS-enriched rice meal decreased the postprandial glycaemic and insulinaemic responses and promoted RS fermentation-related production of H2 in the large bowel of young and healthy Chinese adults.

Large-scale purification and acute toxicity of hygromycin B phosphotransferase.

OBJECTIVE: To provide the acute toxicity data of hygromycin B phosphotransferase (HPT) using recombinant protein purified from E. coli. METHODS: Recombinant HPT protein was expressed and purified from E. coli. To exclude the potential adverse effect of bacteria protein in recombinant HPT protein, bacterial control plasmid was constructed, and bacteria control protein was extracted and prepared as recombinant HPT protein. One hundred mice, randomly assigned to 5 groups, were administrated 10 g/kg, 5 g/kg, or 1 g/kg body weight of HPT or 5 g/kg body weight of bacterial control protein or phosphate-buffered saline (PBS) respectively by oral gavage. RESULTS: All animals survived with no significant change in body weight gain throughout the study. Macroscopic necropsy examination on day 15 revealed no gross pathological lesions in any of the animals. The maximum tolerated dose (MTD) of HPT was 10 g/kg body weight in mice and could be regarded as nontoxic. CONCLUSION: HPT protein does not have any safety problems to human health.

Correlation of serum leptin level with bone mineral density and bone turnover markers in Chinese adolescent dancers.

OBJECTIVE: To investigate plasma leptin concentrations in adolescent female dancers and to determine whether leptin has some effects on their bone mineral density (BMD) and bone turnover markers. METHODS: Sixty dancers aged 15-17 years and 77 healthy controls were enrolled in the study. Bone mineral density (BMD) and body composition were detected by dual energy X-ray absorptiometry. Serum leptin concentrations were measured by radioimmunoassay (RIA). Two bone turnover markers, bone-specific alkaline phosphatase (BAP) and tartrate-resistant acid phosphatase(TRACP), were determined by ELISA. RESULTS: The dancers had a lower fat mass and a lower leptin level than the controls, while they had a relatively higher BMD of the total body and legs after adjustment for BMI and age. The levels of bone resorption and formation of markers were higher in the dancers than in the controls. Leptin was positively correlated with BMI, body weight, fat mass, and percentage of body fat. In dancers, Leptin was positively correlated with the BMD of the total body and the left leg. However, after adjustment for BMI, no correlation of serum leptin concentrations with BMD values was found in either dancers or controls. Nor correlation was found between leptin and bone turnover markers after adjustment for BMI. CONCLUSION: The leptin profile is different between the controls and the dancers with a lower BMI and a lower fat mass. Circulating plasma leptin level depends on BMI and is not a direct determinant of BMD in Chinese adolescent dancers.

[The differences in bone mineral content between female dancers and controls aged 15 - 17 years old and its relationship with physical activity level].

OBJECTIVE: To assess bone mineral content (BMC) of 15 - 17 year-old dancers and high school females and analyze the relationship between physical activity status and BMC. METHODS: Sixty dancers and 77 healthy controls aged 15 - 17 years old were enrolled in our study. BMC in the total body and forearm were measured by dual-energy X-ray absorptiometry (DEXA) while body weight and height were also measured. Physical activity information was collected by "one-year physical activity questionnaire". RESULTS: The physical activity level (PAL) and the average daily energy expenditure (EE) of dancers were all higher than controls (PAL: 2.17 +/- 0.34 vs 1.63 +/- 0.34, t = 7.283; EE: (6876.43 +/- 1036.72) kJ vs (5388.43 +/- 920.83) kJ, t = 7.214, both P values < 0.01). The dancers showed lower BMC/height at total body and arms compared with the controls (the total body BMC/height was (13.896 +/- 1.308) vs (14.494 +/- 1.272) g/cm, F = -2.563); and the BMC/height of left and right arm were (0.779 +/- 0.088) vs (0.829 +/- 0.101) g/cm (F = -2.892) and (0.766 +/- 0.093) vs (0.829 +/- 0.097) g/cm (F = -3.650) respectively, all these P values were < 0.01.Yet after adjusting age and BMI, the dancers showed higher BMC/height at total body and legs, the corresponding values were (14.550 +/- 0.146) vs (13.947 +/- 0.131) g/cm (F = 7.868), (2.681 +/- 0.033) vs (2.389 +/- 0.030) g/cm (F = 36.520), (2.821 +/- 0.031) vs (2.450 +/- 0.028) g/cm (F = 65.279), all these P values were < 0.01. While no differences were found with controls at non-weight bearing sites (arms). Daily period (h) of training was significantly related to BMC/height of legs, total body (r value were 0.618, 0.448 and 0.554 respectively, all the P values < 0.01), while the history of training was also correlated with BMC/height of two legs (r value were 0.38 and 0.304 respectively, both P values < 0.05). CONCLUSION: The adolescent dancers showed higher BMC after adjusting age and BMI, which was attributed to the long-term high level weight-bearing physical activity.