Lactase gene c/t(-13910) polymorphism, calcium intake, and pQCT bone traits in Finnish adults.

Genetic lactase nonpersistence may influence calcium intake and thereby bone health. We investigated in the Cardiovascular Risk in Young Finn Study whether young adults aged 31-46 years with the C/C(-13910) genotype are more susceptible to reduced bone phenotypes, low-energy fractures, and low calcium intake than subjects with other lactase genotypes. We also analyzed the gene-environment interactions on bone with calcium intake and physical activity. Peripheral quantitative computed tomography bone traits were measured from the distal and shaft sites of the radius and tibia. The total number of those subjects whose nondominant forearm was measured and the lactase genotype was defined was 1551. Information on diet, lifestyle factors, and fractures was collected with questionnaires. The mean intake of calcium was the lowest in men with the C/C(-13910) genotype (P = 0.001). Men with the T/T(-13910) genotype had ~3% higher trabecular density at the distal radius and distal tibia compared to other lactase genotypes (P = 0.03 and 0.02, respectively). In women, we found no evidence of the gene effect at the radius and tibia. No major interactions of the C/T(-13910) polymorphism with calcium intake or physical activity on bone phenotypes were found in either sex. In conclusion, the C/T(-13910) polymorphism was associated with trabecular density at the distal radius and tibia in men. These differences may be due to the differences in calcium intake between the lactase genotypes.

Childhood Exposure to Passive Smoking and Bone Health in Adulthood: The Cardiovascular Risk in Young Finns Study.

CONTEXT: Passive smoke exposure has been linked to the risk of osteoporosis in adults. OBJECTIVE: We examined the independent effects of childhood passive smoke exposure on adult bone health. DESIGN/SETTING: Longitudinal, the Cardiovascular Risk in Young Finns Study. PARTICIPANTS: The study cohort included 1422 individuals followed for 28 years since baseline in 1980 (age 3 to 18 years). Exposure to passive smoking was determined in childhood. In adulthood, peripheral bone traits were assessed with peripheral quantitative CT (pQCT) at the tibia and radius, and calcaneal mineral density was estimated with quantitative ultrasound. Fracture data were gathered by questionnaires. RESULTS: Parental smoking in childhood was associated with lower pQCT-derived bone sum index in adulthood (ß± SE, -0.064 ± 0.023 per smoking parent; P = 0.004) in multivariate models adjusted for age, sex, active smoking, body mass index, serum 25-OH vitamin D concentration, physical activity, and parental socioeconomic position. Similarly, parental smoking was associated with lower heel ultrasound estimated bone mineral density in adulthood (ß± SE, -0.097 ± 0.041 per smoking parent; P = 0.02). Parental smoking was also associated with the incidence of low-energy fractures (OR, 1.28; 95% CI, 1.01 to 1.62). Individuals with elevated cotinine levels (3 to 20 ng/mL) in childhood had lower bone sum index with pQCT (ß± SE, -0.206 ± 0.057; P = 0.0003). Children whose parents smoked and had high cotinine levels (3 to 20 ng/mL) had significantly lower pQCT-derived bone sum index compared with those with smoking parents but had low cotinine levels (<3 ng/mL) (ß± SE, -0.192 ± 0.072; P = 0.008). CONCLUSIONS AND RELEVANCE: Children of parents who smoke have evidence of impaired bone health in adulthood.

Higher step count is associated with greater bone mass and strength in women but not in men.

In this cross-sectional study, peripheral bone traits were examined relative to total daily steps measured with pedometer. Higher number of steps was associated with greater bone values at the calcaneus and tibia in women, but not in men. In women, dose-dependent associations at the radius were congruent with the weight-bearing bones. INTRODUCTION: Habitual physical activity measured as daily steps may contribute to bone density and strength at the calcaneus and other weight-bearing bones. METHODS: Subgroups of 705-837 women and 480-615 men aged 31-46 years from the Cardiovascular Risk in Young Finns Study participated in the present study. Participants were instructed to use pedometer for 1 week, and the total daily steps, divided into tertiles, were evaluated relative to quantitative ultrasound-measured bone traits at the calcaneus and peripheral quantitative computed tomography-measured bone traits at the tibia and radius. Analysis of covariance was used to examine the between-group differences. RESULTS: In women, significant dose-dependent between-group differences were found in the weight-bearing bones and in non-weight-bearing radius. The differences in broadband ultrasound attenuation and speed of sound at the calcaneus were 3.8 and 0.5% greater in women within the highest tertile of daily steps compared to the lowest tertile (p values for trend ≤ 0.04). In tibia, women in the highest tertile (> 8765 steps/day) had on average 1-5.4% greater bone cross-sectional area, bone mineral content (BMC), trabecular density, and bone strength index at the distal site and 1.6-2.7% greater bone areas, BMC and strength strain index (SSI) at the shaft compared to women with less daily steps (p values for trend ≤ 0.02). Similarly, in radius, BMC and BSI at the distal site, and bone cross-sectional areas, BMC and SSI at the shaft were 1.7-3.4% greater in women within the highest tertile of daily steps compared to their peers (p values for trend ≤ 0.04). In men, the differences in calcaneal, tibial, and radial bone traits were mainly non-significant between the tertiles of daily steps. CONCLUSION: Observed significant positive associations between daily steps and various bone traits at the calcaneus, tibia, and radius in women suggest that habitual physical activity may benefit skeletal health in adulthood.

Association of apolipoprotein E promoter polymorphisms with bone structural traits is modified by dietary saturated fat intake - the Cardiovascular Risk in Young Finns study.

Association of apolipoprotein E (APOE) ε4 allele with peripheral quantitative computed tomography (pQCT) bone traits at the distal and shaft sites of the radius and tibia was evaluated in the Young Finns Cohort (n=1777). We also analyzed the interactions of the APOE promoter polymorphisms (-219G/T rs405509 and +113G/C rs440446) and bone traits within the APOE ε3/ε3 genotype (n=1025 and n=1013, respectively), and investigated the gene-environment interactions on bone traits with longitudinal saturated fatty acids (SAFA) intake. Differences between the ε4 allele carriers and noncarriers were modest and mostly nonsignificant. Within the APOE promoter -219G/T polymorphism, cortical strength index (CSI) and compressive bone strength index (BSI) at the distal radius (linear, P=0.003 and P=0.05, respectively) and tibia (linear, P=0.01 and P=0.03, respectively), and CSI at the tibial shaft (linear, P=0.04) decreased towards the -219T/T genotype in women. In men, total cross-sectional areas at the radial site and stress-strain index (SSI) at the radial shaft (linear, P=0.03 and P=0.04 and P=0.05, respectively) increased, and conversely cortical bone density and CSI at the radial shaft (linear, P=0.005 and P=0.05, respectively) and CSI at the tibial shaft (linear, P=0.03) decreased towards the -219T/T genotype. In the highest SAFA tertile, women with the -219T/T genotype had the smallest total area and SSI at the radial shaft (P=0.01 and P=0.02, respectively). Subjects with the APOE +113C/C genotype shared similar bone traits as subjects with the APOE -219T/T genotype. In conclusion, APOE genotypes -219T/T and +113C/C could be genetic markers for cortical bone strength. Furthermore, high longitudinal SAFA intake seems to be more detrimental to bone in women with the -219T/T and +133C/C genotypes than others.