First fracture is associated with increased risk of new fractures during growth.

Prior fracture was associated with increased risk of new fracture in 601 members of a cohort studied between birth and l8 years. Hazard ratios for new fracture in data adjusted for age and sex were l.90 (95%CI l.51-2.39) after first fracture and 3.04 (95% CI 2.23-4.15) after second fracture.

Children who avoid drinking cow's milk are at increased risk for prepubertal bone fractures.

The full fracture histories of 50 children (30 girls and 20 boys, age range 3 to 13 years) who had avoided drinking cow's milk for prolonged periods were compared with those in a birth cohort of more than 1,000 children from the same city. Children who avoided milk did not use calcium-rich food substitutes appropriately and had low dietary calcium intakes and low bone mineral density values. Many were overweight (22 of 50). Significantly more of the children who avoided milk reported fractures (16 observed vs 6 expected, chi(2)=31.0, P<.001, df=5). They also experienced more total fractures than the birth cohort population (22 observed vs 8 expected, chi(2)=33.6, P<.001, df=5). All of the fractures occurred before puberty, the majority (18 of 22) being associated with only slight trauma. Forearm fractures were especially common (12 fractures). We conclude that young children avoiding milk are prone to fracture.

Associations of birth weight and length, childhood size, and smoking with bone fractures during growth: evidence from a birth cohort study.

Little information exists on risk factors associated with bone fractures during childhood and adolescence. This 1972/1973-1990/1991 New Zealand study examined the influence of birth size, height and weight throughout growth, smoking, breastfeeding, and sports participation on the risk of fracture in participants of the Dunedin Multidisciplinary Health and Development Study. Information on height, weight, fracture status, and lifestyle was collected at birth and at ages 3, 5, 7, 9, 11, 13, 15, and 18 years from parents and/or participants. Study members sustained 229 (girls) and 393 (boys) fractures between birth and age 18 years. Fracture risk was elevated (per standard deviation unit increase) in relation to birth length (prepubertal fractures only) (risk ratio (RR) = 1.28, 95% confidence interval (CI): 1.04, 1.58), weight at age 3 years (RR = 1.14, 95% CI: 1.03, 1.27), weight from ages 5 to 18 years (RR = 1.15, 95% CI: 1.03, 1.28), height at age 3 years (RR = 1.13, 95% CI: 1.01, 1.26), and height from ages 5 to 18 years (RR = 1.13, 95% CI: 1.02, 1.24). Birth weight, maternal smoking, breastfeeding, and sports participation had no significant effect on fracture risk. However, for teenagers, personal daily smoking increased the risk of fracture (RR = 1.43, 95% CI: 1.05, 1.95). The authors concluded that tall and heavy children had an increased risk of fracture, as did adolescents who smoked regularly.

Body fat percentages measured by dual-energy X-ray absorptiometry corresponding to recently recommended body mass index cutoffs for overweight and obesity in children and adolescents aged 3-18 y.

BACKGROUND: Body mass index (BMI; in kg/m2) cutoffs for use with children and adolescents aged 2-18 y that correspond to the well-accepted BMI cutoffs for overweight (> or = 25 but < 30) and obesity (> or = 30) in adults were published recently. OBJECTIVE: The objective was to estimate the percentage body fat (%BF) values typically associated with these BMI cutoffs in children and adolescents. DESIGN: The %BF was measured by dual-energy X-ray absorptiometry in 661 subjects (49% male) aged 3-18 y. Regression equations using BMI, age, and sex were developed to predict the %BF associated with BMI cutoffs for overweight (age-specific BMI equivalent to a BMI of 25 in an 18-y-old) and obesity (age-specific BMI equivalent to a BMI of 30 in an 18-y-old) over this age range. RESULTS: Measurements classified 17.1% of males and 19.8% of females as overweight and 5.5% of males and 7.5% of females as obese. The %BF associated with an obese BMI tended to be higher in peripubertal males (34-36%) than in younger (24-30%) or older (27-30%) males. Although the predicted %BF of young females was similar to that of young males, values rose steadily with age, such that an 18-y-old female with a BMI of 30 had an estimated %BF of 42%, whereas that in males of similar age was 27%. CONCLUSION: The %BF values associated with BMI classifications of overweight and obesity vary considerably with age in growing children, particularly in girls.

Children who avoid drinking cow milk have low dietary calcium intakes and poor bone health.

BACKGROUND: Information concerning the adequacy of bone mineralization in children who customarily avoid drinking cow milk is sparse. OBJECTIVE: The objective was to evaluate dietary calcium intakes, anthropometric measures, and bone health in prepubertal children with a history of long-term milk avoidance. DESIGN: We recruited 50 milk avoiders (30 girls, 20 boys) aged 3-10 y by advertisement. We measured current dietary calcium intakes with a food-frequency questionnaire and body composition and bone mineral density with dual-energy X-ray absorptiometry and compared the results with those of 200 milk-drinking control children. RESULTS: The reasons for milk avoidance were intolerance (40%), bad taste (42%), and lifestyle choice (18%). Dietary calcium intakes were low (443 +/- 230 mg Ca/d), and few children consumed substitute calcium-rich drinks or mineral supplements. Although 9 children (18%) were obese, the milk avoiders were shorter (P < 0.01), had smaller skeletons (P < 0.01), had a lower total-body bone mineral content (P < 0.01), and had lower z scores (P < 0.05) for areal bone mineral density at the femoral neck, hip trochanter, lumbar spine, ultradistal radius, and 33% radius than did control children of the same age and sex from the same community. The z scores for volumetric (size-adjusted) bone mineral density (g/cm(3)) were -0.72 +/- 1.17 for the lumbar spine and -0.72 +/- 1.35 for the 33% radius (P < 0.001). Twelve children (24%) had previously broken bones. CONCLUSIONS: In growing children, long-term avoidance of cow milk is associated with small stature and poor bone health. This is a major concern that warrants further study.

Four-year gain in bone mineral in girls with and without past forearm fractures: a DXA study. Dual energy X-ray absorptiometry.

We have previously shown that girls with a recent distal forearm fracture have weaker skeletons than girls who have never fractured. This could be a transient or persistent phenomenon. The present study was undertaken to determine whether the bone mineral content (BMC) of girls with previous distal forearm fractures remains lower 4 years postfracture or if catch-up gain has occurred. We report baseline and follow-up dual energy X-ray absorptiometry (DXA) results for 163 girls: 81 girls from the original control group who remained free of fracture (group 1) and 82 girls from the original group with distal forearm fractures (group 2). In data adjusted for bone area, height, weight, and pubertal status, group 2 girls had 3.5-8.5% less BMC at the total body, lumbar spine, ultradistal radius, and hip trochanter than group 1 at baseline, and 2.4-5.7% less BMC at these sites at follow-up. Even girls from group 2 who did not experience another fracture after baseline (n = 58) did not display greater BMC at follow-up compared with baseline values at any site, indicating that the decreased BMC at the time of fracture had persisted. In group 2, the relative gain in BMC after adjusting for the initial BMC and current bone area, height, weight, and pubertal stage was less than or similar to, but not greater than that of group 1 (ratio [95% CI]: total body, 0.985 [0.972-0.998]; lumbar spine, 0.961 [0.935-0.987]; ultradistal radius, 0.968 [0.939-0.998]; hip trochanter, 0.955 [0.923-0.988]; femoral neck, 0.981 [0.956-1.007]; and 33% radius 0.999 [0.977-1.021]). These findings indicate that girls with distal forearm fractures do not improve their gain of BMC. We conclude that girls who have sustained a distal forearm fracture maintain their lower BMC at most sites for at least 4 years.

Intensive lifestyle changes are necessary to improve insulin sensitivity: a randomized controlled trial.

OBJECTIVE: The extent to which lifestyle must be altered to improve insulin sensitivity has not been established. This study compares the effect on insulin sensitivity of current dietary and exercise recommendations with a more intensive intervention in normoglycemic insulin-resistant individuals. RESEARCH DESIGN AND METHODS: Seventy-nine normoglycemic insulin-resistant (determined by the euglycemic insulin clamp) men and women were randomized to either a control group or one of two combined dietary and exercise programs. One group (modest level) was based on current recommendations and the other on a more intensive dietary and exercise program. Insulin sensitivity was measured using a euglycemic insulin clamp, body composition was measured using dual-energy X-ray absorptiometry, and anthropometry and aerobic fitness were assessed before and after a 4-month intervention period. Four-day dietary intakes were recorded, and fasting glucose, insulin, and lipids were measured. RESULTS: Only the intensive group showed a significant improvement in insulin sensitivity (23% increase, P=0.006 vs. 9% in the modest group, P=0.23). This was associated with a significant improvement in aerobic fitness (11% increase in the intensive group, P=0.02 vs. 1% in the modest group, P=0.94) and a greater fiber intake, but no difference in reported total or saturated dietary fat. CONCLUSIONS: Current clinical dietary and exercise recommendations, even when vigorously implemented, did not significantly improve insulin sensitivity; however, a more intensive program did. Improved aerobic fitness appeared to be the major difference between the two intervention groups, although weight loss and diet composition may have also played an important role in determining insulin sensitivity.