Familial resemblance of bone mineral density between females 18 years and older and their mothers.

Potential determinants of bone mass were investigated in a group of 70 young females (mean age 26.6 years), daughters of women studied in premenopause. Nutritional data, leisure physical activity level, lifestyle habits as well as familial similarities were assessed. The daughters' bone mineral density (BMD), measured by dual-energy absorptiometry, was significantly correlated with their body mass index (BMI) (r = 0.22), dietary vitamin D intake (r = 0.19) and their mothers' BMD (r = 0.44). Multiple regression analysis indicated that only the mothers' BMD remained an independent predictor of bone mass. Mother-daughter correlations were also observed for body weight (r = 0.24), height (r = 0.39), BMI (r = 0.29), dietary calcium intake (r = 0.20), and calcium (r = 0.20) or vitamin D (r = 0.25) intakes from dairy products. Hence, these observations support the evidence that mothers' BMD is the strongest predictor of bone mass of young women in their third decade.     

Familial resemblance of bone mass in adult women

Bone mass may be so reduced in some individuals as to be characterized as osteoporotic, with resulting fracture, particularly of the proximal femur, vertebrae, or wrist. We identified 34 mother-daughter sets (n = 70) and 29 sibling sets (n = 59) from a community study of bone mass correlates to assess the degree of resemblance in bone mass within and between generations. We hypothesized that if between- and within-generation correlations of bone mass in first-degree relatives were of sufficient magnitude, then an important genetic influence in osteoporosis might be considered. Bone mass was measured at the distal radius using a single-beam photon absorptiometer. Height, weight, triceps skinfold thickness, and mid-arm circumference were also measured, and the latter two measurements used to compute humeral muscle area. We identified a significant resemblance in height among the sibling sets. We found no consistent evidence for significant resemblance of bone mass among women when considering mother-daughter sets or sibling sets.     

Calcium intake, physical activity and bone mass in pre-menopausal women

Thirty pre-menopausal women aged 35–40 years were assessed with respect to dietary calcium intake, physical activity and other factors related to bone loss (by questionnaire); bone mass in the mid and distal femur measured by computerized tomography; and leg strength and muscle size. Cortical thickness at mid-femur was negatively associated with breast-feeding (r=-0.40). Bone mass in the distal femur was negatively associated with age (r=-0.46) and positively associated with activity (r=0.44) and leg strength (r=0.42). There was no association of bone mass at either site with current dietary calcium intake (range 198–1511 mg/day), nor with body mass index (BMI), hand-grip strength, parity, oral contraceptive use, smoking, or alcohol intake. Thus, in older pre-menopausal women, activity apparently helps to maintain bone mass at the distal femur, a site of high trabecular bone content, while current dietary-calcium intake has no effect on bone mass in the femur. Activity was most strongly associated with bone mass in the distal femur when it was defined as the total number of hours spent standing or moving (i.e. other than sitting or lying down), regardless of the intensity of activity.
The strong negative association between bone mass in the distal femur and age in older pre-menopausal women is of concern in relation to long-term risk of osteoporotic related fracture, suggesting that factors relating to bone loss in this age-group should be studied longitudinally. The apparent loss of cortical bone in breast-feeders warrants further investigation.     

Familial resemblance in energy intake: contribution of genetic and environmental factors

Total energy intake and intakes of carbohydrate, fat, and protein as well as the percentage of energy derived from these nutrients were calculated from a 3-d dietary record in 1597 subjects living in 375 families of French descent. Familial correlations were computed in pairs of biological relatives and relatives by adoption and used in the path-analysis BETA model to determine the contribution of genetic and nongenetic factors in the familial resemblance observed in energy intake. No significant genetic effect was found for intake of any nutrient tested (h2 less than or equal to 11%) and cultural inheritance was found to be more important than genetic inheritance. Nontransmitted environmental factors, including home environmental effects, were found to account for more than 50% of the variation observed in the energy-intake components. These results suggest that the average genetic influence on nutrient intake is negligible and that nongenetic effects associated mainly with home environmental effects are the major affecters of energy intake.     

Effects of home- and university-based programs on physical self-perception in mothers and daughters

The primary purpose of this study was to compare two mother-daughter interventions designed to increase fitness and activity and improve physical self-perception (PSP).A secondary purpose was to test two of the proposed mechanisms for using physical activity to enhance PSP. Twenty mother-daughter pairs (n = 40) were randomly assigned to a university-based (UB) or home-based (HB) group. Initially, both groups received classroom training designed to improve PSP. Then, the UB group met three times per week, whereas the HB group received information concerning home-based activities. The Fitnessgram activity questionnaire and fitness test battery were used to measure physical activity and fitness level. The Physical Self-Perception Profile (PSPP) was used to detect changes in PSP. Separate 2 (group) x 2 (age) x 2 (time) ANOVAs with repeated measures on the last factor were conducted to examine changes in PSP, physical activity, and fitness. Correlations between physical activity, fitness, and PSP were examined to test the two mechanisms. Perceived sports competence and body attractiveness improved in UB and HB mothers and daughters (p =.002 and.005, respectively). UB and HB mothers and daughters increased their participation in aerobic (p =.000 and.015), muscular strength (p =.001 and.001), and flexibility (p =.000 and.000) activities. Support was not provided for the proposed mechanisms for the relationship between physical activity and PSP. These interventions demonstrate the potential to foster positive short-term changes in PSP and physical activity in mothers and daughters. More research is needed to test mechanisms explaining the relationship between activity and PSP.     

Familial resemblance of body composition in prepubertal girls and their biological parents

BACKGROUND: Heritability estimates for body mass index (BMI; in kg/m(2)) in children generally have been derived from twin and adoption studies. However, BMI does not reflect total or regional body composition. OBJECTIVE: We evaluated the familial resemblance of body composition between prepubertal girls of normal weight and body fatness and their parents by using state-of-the-art technology. DESIGN: The subjects were 101 girls [mean age: 8.5 +/- 0.4 y; percentage body fat (%BF): 12-30%] and their biological parents. Weight, height, and body composition [fat mass (FM), fat-free mass (FFM), and %BF] were measured with dual-energy X-ray absorptiometry (DXA) and total body potassium (TBK). RESULTS: Weight, height, and BMI showed low-to-moderate similarity between the girls and both their parents (r = 0.29-0.44, P < 0.01). The girls' FM, FFM, and %BF were significantly related to both parents' body composition. Cross-generational equations were developed for DXA, eg, child's %BF = 12.4 + (0.158 paternal %BF) + (0.145 maternal %BF) (adjusted r(2) = 0.16, P < 0.001). Regional analysis with DXA showed that the adjusted r(2) values for the arm, trunk, and leg regions, respectively, were 0.17, 0.33, and 0.31 for lean tissue mass and 0.11, 0.14, and 0.09 for FM. TBK showed a similar relation between parents and girls (r = 0.28-0.47, P < 0.01). Significant heritability (h(2) +/- SE) was detected for BMI (0.35 +/- 0.17, P = 0.03) and %BF measured with DXA (0.50 +/- 0.12, P = 0.0001). CONCLUSION: The body composition of prepubertal girls of normal weight and body fatness is significantly related to the body composition of both biological parents.     

Osteoporosis knowledge,calcium intake,and weight-bearing physical activity in three age groups of women

The purpose of this study was to determine the extent and integration of osteoporosis knowledge in three age groups of women and compare knowledge to calcium intake and weight-bearing physical activity (WBPA). In this cross-sectional study, knowledge, calcium intake and WBPA were assessed using probe interviews, a food frequency and an activity questionnaire, respectively. Seventy-five white women were separated into three groups: young (25–35 years), middle aged (36–46 years) and postmenopausal (50+ years). Concept maps were used to assess knowledge (concepts, integration and misconceptions). Calcium intakes from diet, supplements and fortified orange juice were estimated as were minutes of daily WBPA. Analysis of covariance was used to compare knowledge, calcium intake and WBPA by age group. Covariates included education, family history, physical problems making exercise difficult, and lactose intolerance. Chi square analysis was used to determine differences in these covariates across age groups. Correlations and regression analysis were used to determine relationships between knowledge and behaviors. Knowledge scores averaged 32–44 points (183 possible). Average calcium intake in all groups exceeded the Dietary Reference Intake's recommended Adequate Intake but 20–24% consumed less than 60% of the AI. Housework, walking at work, and standing at home and work accounted for 90% of WBPA. Knowledge about osteoporosis was limited and not associated with age, WBPA or calcium intake. Calcium intake and WBPA were not associated with age. Practitioners need to provide explicit information on osteoporosis and risk reducing behaviors to women of all ages.     

Familial correlates of adolescent girls' physical activity,television use,dietary intake,weight, and body composition

Background  

The family environment offers several opportunities through which to improve adolescents' weight and weight-related behaviors. This study aims to examine the cross-sectional relationships between multiple factors in the family environment and physical activity (PA), television use (TV), soft drink intake, fruit and vegetable (FV) intake, body mass index (BMI), and body composition among a sample of sociodemographically-diverse adolescent girls.     

Physical activity, calcium intake, and bone mineral content in children in The Netherlands.

STUDY OBJECTIVE--To examine the relation between physical activity, calcium intake, and bone mineral content in children. DESIGN--Population based, cross sectional study. SETTING--Primary schools in Zoetermeer, The Netherlands. PARTICIPANTS--Altogether 1359 Dutch boys and girls, aged 7 to 11 years (response rate 88%). MEASUREMENTS--Bone mineral content was measured by quantitative roentgen microdensitometry of the midphalanx of the second digit at the diaphyseal and metaphyseal site. Maximal exercise testing, according to the Bruce treadmill protocol, was used to assess physical fitness. Habitual physical activity was assessed by use of a questionnaire on physical activities. Daily calcium intake from dairy products was estimated by use of a semiquantitative food frequency questionnaire. MAIN RESULTS--Bone mineral content in boys was not linearly associated with physical fitness after adjustments for differences in height, body weight, chronological age, and skeletal age. In girls a linear association was found at the metaphyseal site only. When extreme groups were compared, bone mineral content was found to be higher in "high fitness children" (upper decile) than "low fitness children" (lowest decile), with statistical significance reached in boys only. When analyses were performed in subgroups of skeletal age, a clear linear relation between physical fitness and bone mineral content was seen in the mature subgroup in both boys and girls. No linear association was found between habitual physical activity and bone mineral content, while the results in extreme groups (that is, upper versus lowest decile) and in subgroups of skeletal age were comparable to those on physical fitness in boys only. No association was found between daily calcium intake and bone mineral content in this age group. CONCLUSIONS--This cross sectional study in children aged 7 to 11 years suggests that an increased bone mineral content is found only in those with a high level of physical activity. This association is most pronounced in the more mature children. No evidence was found for an association between daily calcium intake and bone mineral content in childhood.     

Calcium intake,calcium bioavailability and bone health

Calcium accounts for 1-2 % of adult human body weight. Over 99 % of total body Ca is found in the teeth and bones. Therefore, in addition to the obvious structural role of the skeleton, it also serves as a reservoir for Ca. Dietary Ca intake has an important impact on bone metabolism and bone health. Chronic Ca deficiency resulting from inadequate intake or poor intestinal absorption is one of several important causes of reduced bone mass and osteoporosis. It is vital, therefore, that adequate dietary Ca is consumed at all stages of life - in early life so that the genetically programmed peak bone mass can be reached and in later adulthood so that the skeletal mass can be maintained and age-related bone loss minimised. Unfortunately, there is wide variation in the estimates of daily Ca requirements made by different expert authorities. Furthermore, there is evidence that many individuals are not consuming these recommended levels. The consequence of this for bone health will be discussed in the present review. Besides the amount of Ca in the diet, the absorption of dietary Ca in foods is also a critical factor in determining the availability of Ca for bone development and maintenance. Thus, there is a need to identify food components and/or functional food ingredients that may positively influence Ca absorption in order to ensure that Ca bioavailability from foods can be optimised. This approach may be of particular value in individuals who fail to achieve the dietary recommended level of Ca.     

Increasing weight-bearing physical activity and calcium intake for bone mass growth in children and adolescents: a review of intervention trials

OBJECTIVE: The purpose of this review is to evaluate the current state-of-the-science for interventions to increase bone mass gains in children and adolescents using weight-bearing physical activity or calcium supplementation. METHODS: Studies were located using computerized and manual searches of the empirical literature. Inclusion criteria were: (a) intervention study targeting weight-bearing physical activity or calcium intake; (b) inclusion of a control group; (c) subject age range under 18 years; and (d) outcome measured bone mineral density or bone mineral content. RESULTS: Weight-bearing physical activity and calcium supplement intervention studies both consistently show positive effects on bone mass gains in children and adolescents. The most consistent findings for both weight-bearing physical activity and calcium were for lumbar spine and total body bone sites. Only weight-bearing physical activity interventions had significant effects on the femoral neck sites. Low power may have contributed to the lack of statistically significant findings in several studies and also prevented proper evaluation of potential interactions between pubertal status and interventions on bone mass gains. CONCLUSIONS: Increases in weight-bearing physical activity or calcium intake have positive effects on bone mass gains in children and adolescents. Further research is needed to evaluate: (a) the long-term durability of these effects; (b) specific dose-response associations; (c) interactions between weight-bearing physical activity and calcium intake; and (d) interactions between pubertal development and weight-bearing physical activity or calcium intake on bone mass outcomes.     

Association of physical exercise and calcium intake with bone mass measured by quantitative ultrasound

Background  

Interventions other than medications in the management of osteoporosis are often overlooked. The purpose of this study was to investigate the association of physical activity and calcium intake with bone parameters.     

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.     

Lifetime calcium intake and physical activity habits: independent and combined effects on the radial bone of healthy premenopausal Caucasian women

Lifetime calcium intake and lifetime physical activity (PA) habits of 181 healthy premenopausal Caucasian women (aged 20-50) were studied. Nondominant arm was measured by single-photon absorptiometry at the distal (Dis) or 5-mm site and the midshaft (Mid) or two-thirds site of the radius. Values of bone mineral content (BMC), bone width (BW), and bone mineral density (BMD) were obtained. An intermediate or high lifetime Ca (greater than 500 mg/d) was significantly associated with a greater DisBMC (p = 0.0031), DisBMD (p = 0.0031), MidBMC (p = 0.0015), and MidBMD (p = 0.0015) when adjusted for PA. Similarly, with Ca adjusted for, a high lifetime PA (greater than or equal to 45 min of moderate to strenuous activity four times a week) was significantly associated with greater DisBMC (p = 0.0032), DisBMD (p = 0.0022), MidBMC (p = 0.0012), MidBW (p = 0.0173), and MidBMD (p = 0.0546). These findings suggest important roles for both adequate Ca intake and PA habits in enhancing peak adult skeletal mass and a trade-off between these two variables, when each was intermediate or higher.     

乳糖不耐受与钙摄取和骨健康研究进展

乳糖不耐受被认为与钙摄取和骨健康息息相关。目前普遍认为乳糖不耐受会降低钙摄入量,但对于钙吸收率的影响至今仍有较大的争议。在乳糖不耐受人群中,乳糖可能是影响钙吸收的重要因素,而早期研究设计中的不同乳糖剂量负荷也可能是导致不同结果的原因。而近十几年的研究发现乳糖酶相关基因类型是影响钙摄入与骨健康的重要因子。然而既往研究受限于知识技术的限制,研究内与研究间的异质性过大,这导致了相关研究出现相互矛盾的数据聚集。这也迫使当下进行更可靠的大样本对照研究来探讨乳糖不耐受与钙摄取和骨健康的相关性。     

Familial aggregation of nutrient intake and physical activity: results from the San Antonio Family Heart Study

PURPOSE: To evaluate the extent to which levels of physical activity and nutrient intake aggregate in families, and secondarily, to assess the repeatability of these behavioral measures over a 5-year period. METHODS: Measurements were obtained in a population-based sample consisting of 1364 members of 42 large Mexican American families. Nutrient intake was assessed by a food frequency questionnaire validated for use in this population. Usual level of physical activity was estimated using a 7-day recall questionnaire. RESULTS: Correlations between baseline (obtained 1992-1995) and follow-up (obtained 1996 to 2000) measures of all behaviors were highly significant (p < 0.001), ranging from 0.24 for % of calories derived from fat to 0.44 for % of calories derived from alcohol. Familial effects, estimated using variance component methods, were stronger when modeled as a genetic heritability than as a shared household effect; as a heritability they accounted for a significant portion of the total variation of all traits (9% for physical activity levels, p < 0.05; and 13-26% for nutrient intake, p < 0.001 for all). CONCLUSIONS: Measurements of physical activity and dietary behaviors in this population tracked over 5 years, and there was a significant degree of aggregation of these behaviors within families. Understanding the sources of these family effects may facilitate efforts to improve cardiovascular health.