Heather Greenfield

School-milk intervention trial enhances growth and bone mineral accretion in Chinese girls aged 10-12 years in Beijing.

A 2-year milk intervention trial was carried out with 757 girls, aged 10 years, from nine primary schools in Beijing (April 1999 - March 2001). Schools were randomised into three groups: group 1, 238 girls consumed a carton of 330 ml milk fortified with Ca on school days over the study period; group 2, 260 girls received the same quantity of milk additionally fortified with 5 or 8 microg cholecalciferol; group 3, 259 control girls. Anthropometric and bone mineralisation measurements, as well as dietary, health and physical-activity data, were collected at baseline and after 12 and 24 months of the trial. Over the 2-year period the consumption of this milk, with or without added cholecalciferol, led to significant increases in the changes in height (> or =0.6 %), sitting height (> or =0.8 %), body weight (> or 2.9 %), and (size-adjusted) total-body bone mineral content (> or =1.2 %) and bone mineral density (> or =3.2 %). Those subjects receiving additional cholecalciferol compared with those receiving the milk without added 25-hydoxycholecalciferol had significantly greater increases in the change in (size-adjusted) total-body bone mineral content (2.4 v. 1.2 %) and bone mineral density (5.5 v. 3.2 %). The milk fortified with cholecalciferol significantly improved vitamin D status at the end of the trial compared with the milk alone or control groups. It is concluded that an increase in milk consumption, e.g. by means of school milk programmes, would improve bone growth during adolescence, particularly when Ca intake and vitamin D status are low.

Low Vitamin D Status Has an Adverse Influence on Bone Mass, Bone Turnover, and Muscle Strength in Chinese Adolescent Girls

Our goal in this cross-sectional study was to investigate the influence of low-vitamin D status on bone mass, bone turnover, and muscle strength in 301 healthy Chinese adolescent girls. Blood plasma 25-hydroxyvitamin D [25(OH)D] was measured by RIA and plasma and urine biomarkers of bone turnover were measured. Bone mineral content (BMC) and density and bone area for the whole body and the distal and proximal forearm were measured by dual energy X-ray absorptiometry. When vitamin D deficiency was defined as a serum 25(OH)D concentration of < or =50 nmol/L and severe deficiency as <25 nmol/L, 57.8% of subjects were vitamin D deficient and 31.2% were severely deficient. Multivariate analysis shows that girls with adequate vitamin D status had higher size-adjusted BMC for the whole body (P < 0.001), distal forearm (P < 0.001), and proximal forearm (P < 0.01) than those with poorer vitamin D status after adjusting for body size, handgrip strength, physical activity, and dietary intakes of calcium and vitamin D. Similar results were also found for handgrip muscle strength. Participants with adequate vitamin D status had significantly lower concentrations of bone alkaline phosphatase in plasma and deoxypyridinoline:creatinine ratio in urine compared with those of the vitamin D-deficient girls. Adolescent girls with adequate vitamin D status had significantly higher bone mass and muscle strength compared with those with poor vitamin D status. This may be attributed in part to a lower rate of bone remodeling with adequate vitamin D status. These findings suggest that adequate vitamin D status during adolescence is important for optimizing bone mass, which may lead to higher peak bone mass at maturity. Poor vitamin D status also compromises forearm muscle strength.

Milk consumption and bone mineral content in chinese adolescent girls

A cross-sectional study of a random sample of 649 girls, aged 12-14 years (mean +/- SD: 12.9 +/- 0.6 years), in the Beijing area examined the relationship between diet and bone mineral status. Food and nutrient intakes over the past year were estimated by means of a semiquantitative food frequency questionnaire. Bone mineral content (BMC) and bone width (BW) at the distal one-third and one-tenth radius and ulna were measured by single-photon absorptiometry. Results showed Beijing pubertal girls had a low mean milk consumption (fresh and powdered milk, vitamin D-fortified milk, and yogurt) at 50 g/day (95% confidence interval [CI] 44-55 g/day whereas one-third consumed no milk at all. Mean calcium intake was 356 +/- 97 mg/day of which only 21% was provided by milk and milk products. Milk intake varied by region (rural, suburban, and urban: 9, 36, and 83 g/day, respectively, p < 0.0005) as did the proportion of milk consumers in the three areas (30%, 64%, and 91%, p < 0.0005). Bone mineral density (BMD) at the distal one-third and one-tenth radius and one-tenth ulna was positively associated with milk consumption (p < 0.05). Multiple regression analysis of BMC on foods and nutrients as well as confounding factors, including weight, bone age, Tanner stage, and School Physical Activity Score (SPAS), showed that milk intake was the only dietary factor included in the models for BMC at the four bone sites measured. The model explained 54%-65% of the variation in BMC, and milk alone accounted for up to 3.2% of the variation. Milk was the only food group with significant partial correlation with BMC. SPAS, weight, bone age, and Tanner stage each accounted for a smaller variation in BMC (<1.8%). The results indicate that milk (presumably as an integrated source of nutrients) had a beneficial effect on bone mass of Beijing pubertal girls and was a better nutritional determinant of BMC than intake of any milk nutrient alone. Promotion of milk consumption should be considered for achieving optimal bone mass in this population group.

Influence of body composition, muscle strength, diet and physical activity on total body and forearm bone mass in Chinese adolescent girls

The aim of the present study was to determine association between body composition, muscle strength, diet and physical exercise with bone mineral content (BMC) and bone area (BA) in 283 Chinese adolescent girls aged 15 years in Beijing, China. Body composition, pubertal stage, physical activity and dietary intakes were assessed using standard validated protocols. Total body and forearm bone, lean body mass (LBM) and fat body mass (FBM) were determined by dual X-ray absorptiometry. Multivariate linear regression analyses were carried out to examine the predictors of BMC and BA, after controlling for potential confounders. The subjects had a mean age of 15.0 (sd 0.9) years and 99.6 % of them had reached menarche. Multivariate analyses showed that LBM, FBM, handgrip muscle strength and milk intake were significant independent determinants of BMC and BA of the total body and/or forearm sites. LBM was found to be a stronger independent determinant than FBM of BMC and BA, whereas handgrip muscle strength was only found as significant determinant of BMC and BA at the forearm sites than in total body BMC and BA. Further, total physical activity level had a significant positive association with handgrip and LBM. This suggested that greater muscle strength and higher LBM may reflect higher levels of physical activity. Therefore, continuous healthy lifestyle practices such as adequate intake of milk and continuous participation in physical activity should be encouraged throughout adolescence to optimise bone growth during this period.

Fat uptake during deep-fat frying of coated and uncoated foods

Abstract Twenty animal and plant foods (1.5-cm cubes) were deep-fat fried for varying times and their fat contents were determined. Sixteen of the foods absorbed frying fat (6.1 to 86.3 g/ 100 g, dry weight basis), with the higher amounts being absorbed into the plant foods that initially had high water and low fat contents than into the animal foods (up to 21.8 g fat absorbed/ 100 g). One animal food underwent a net loss of fat, while three animal foods showed no significant change in fat. Fish sticks were coated with six types of coatings and deep-fat fried. Frying fat uptake into the coating, fish, and the total product was measured. Batters but not breadings markedly retarded fat movement into the fish.

Improvement of bone health in childhood and adolescence

Osteoporosis as a worldwide problem is discussed in the present review and the question of improving peak bone mass to reduce the risk of osteoporosis and osteoporotic fracture is addressed. The available evidence points to pre-puberty and puberty as the most opportune periods for intervention, but the potential for achievable increments in bone mass is shown to be small compared with the overwhelming influence of heredity, body composition and hormonal factors on bone. Lean body mass appears to be positively correlated with bone mass, while black-white racial differences in bone mass appear to be related to greater lean mass and lower bone turnover rate in blacks. Within races, twin and parent-offspring models have suggested that 46-80 % of the variance in bone mineral density can be explained by inherited factors; however, the mechanism of the genetic influence on bone density remains poorly understood. Moderate regular exercise seems to maintain bone mass while more vigorous regular exercise increases it in children and young adults. Ca intake has been found to be positively associated with bone mass in many but not all studies, possibly because of a ceiling at about 1300-1500 mg/d for young people. Other nutritional variables, including vitamin D, have been little investigated in relation to childhood and adolescent bone mass. The influence of milk as a source of highly bioavailable Ca and other nutrients has also been less frequently investigated, which is of concern given the cessation of school milk programmes in Western countries over the last three decades. Intervention studies to improve bone health in young people have mainly been based on Ca milk or exercise. The evidence points to the benefits to bone of such interventions, particularly when commenced pre-puberty, and it seems that daily consumption of 200-300 ml milk/d by children and adolescents has no adverse side effects. The benefits to bone are almost universally shown to be lost fairly rapidly after Ca or exercise intervention ceases; there is therefore no justification in terms of bone health for short-term interventions of this nature. The question of withdrawal of milk supplementation has undergone very little examination. Further, very little evidence is available on the effects of long-term interventions of any sort on bone health. Nevertheless, the data obtained so far permit the suggestion that promotion of Ca intake (e.g. at the higher level of current recommendations) and exercise commencing in the pre-pubertal period should be adopted as policy now.

Growth and Bone Mineral Accretion During Puberty in Chinese Girls: A Five-Year Longitudinal Study

There are few longitudinal data on bone development during puberty in children with low calcium intake. This 5‐yr longitudinal study showed that, in Chinese girls, the mean apparent calcium retention efficiency during puberty was 40.9%, PHV occurred at 3–0 yr before menarche, and peak bone mineral accretion occurred 1 yr later than PHV. Chinese girls have high calcium retention efficiency during puberty.

Bone mass in Chinese premenarcheal girls: the roles of body composition, calcium intake and physical activity

The association of growth and anthropometric characteristics and lifestyle factors with bone mass and second metacarpal radiogrammetry parameters was evaluated in 373 healthy Chinese premenarcheal girls aged 9-11 years. Bone mineral content (BMC) and density (BMD) and bone area (BA) of distal forearm, proximal forearm and total body, bone mineral-free lean (BMFL) mass and fat mass were measured by dual-energy X-ray absorptiometry. Metacarpal bone periosteal and medullary diameters were measured. Dietary intakes were assessed by 7 d food record and physical activity (PA) by questionnaire. BMFL and fat mass together explained 6.3 and 51.6% of the variation in total body BMC and BMD, respectively. BMFL mass contributed to a substantial proportion of the variation in forearm BMC and BMD and periosteal diameter (10.4-41.0%). The corresponding BA explained 14.8-80.4% of the variation in BMC. Other minor but significant predictors of total body bone mass were Ca intake, height, age and PA score (BMD only), and of forearm bone mass were PA score, bone age, height and fat mass. Nevertheless, after adjusting for bone and body size and for age or bone age, subjects with Ca intake above the median (417 mg/d) had 1.8% greater total body BMC (P<0.001), and subjects with PA scores above the median had 2.4-2.5% greater distal and proximal forearm BMC (P<0.05) than those below. Vitamin D intake negatively associated with medullary diameter (partial R2 1.7%). The results indicate that premenarcheal girls should be encouraged to optimise nutrition and Ca intake and exercise regularly to achieve maximum peak bone mass.

The association between dietary protein intake and bone mass accretion in pubertal girls with low calcium intakes.

To assess the association between protein intakes and bone mass accrual in girls, data were analysed for 757 pre-pubertal girls (mean age 10.1 years) in urban Beijing, China, who participated in a 5-year study including 2 years of milk supplementation (intervention groups only) and 3 years of follow-up study. At 0, 12, 24, 48 and 60 months from the baseline, bone mass of the proximal or distal forearm (PF or DF) and total body (TB) was measured with dual energy X-ray absorptiometry; dietary intakes were assessed by a 3-d food record (including two weekdays and one weekend day). Linear mixed models were used and continuous variables were logarithm transformed. The mean longitudinal Ca intake (432-675 mg/d on average) positively influenced bone mineral content (BMC) at TB, PF and DF after controlling for baseline bone mass and other possible confounders. However, negative associations were observed between protein intake (55.9-61.0 g/d on average) and BMC accrual at TB, PF or DF (beta = - 1.92, - 10.2 or - 4.82, respectively, P < 0.01) after adjustment. When protein intake was considered according to animal or plant food sources, protein from animal foods, particularly meat, had significant negative effects on BMC accrual at DF or PF after adjustment. It was concluded that higher protein intake, especially from animal foods, appeared to have a negative effect on bone mass accrual in Chinese pubertal girls with low Ca intakes.

Lipid composition of Australian retail lamb cuts with differing carcass classification characteristics.

The gross, proximate, fatty acids and cholesterol composition of three raw retail cuts from 28 lambs classified by weight, sex and fatness score were investigated. For gross composition, cut weight increased significantly with fat score and carcass weight. Percentage fat increased significantly from fat score 1-2 but not beyond (P<0.05). For nutrient composition the fat contents of the total cut and lean only portion of the three cuts increased directly with fat score by 10 g/100 g and 1.7 g/100 g, respectively. Fat content increased mainly at the expense of moisture. Cholesterol content of total cut and lean only portions decreased with increased fat score, by 16 and 18 mg/100 g, respectively. For lean only levels of myristic and palmitic acids increased significantly (P<0.05) while stearic acid decreased significantly, while levels of linoleic and linolenic acids decreased significantly with increased fat score.