Effect of Vitamin D Supplementation on Bone Mass in Infants With 25-Hydroxyvitamin D Concentrations Less Than 50 nmol/L: A Prespecified Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

The dose of supplemental vitamin D needed in infants born with serum 25-hydroxyvitamin D (25[OH]D) concentrations less than 50 nmol/L (ie, 20 ng/mL) is unclear.

OBJECTIVE

To determine whether a higher dose (1000 IU vs 400 IU per day) is required in infants born with 25(OH)D concentrations less than 50 nmol/L for bone mineral accretion across infancy.

DESIGN, SETTING, AND PARTICIPANTS

In this prespecified secondary analysis of a double-blinded randomized clinical trial, conducted from March 2016 to March 2019 in a single center in Greater Montreal, Quebec, Canada, a consecutive sample of 139 healthy term singletons were recruited from 866 infants screened for vitamin D status at birth. Data were analyzed from June 2021 to November 2022.

INTERVENTIONS

Capillary blood was collected 24 to 36 hours after birth to measure serum total 25(OH)D concentrations. Infants with 25(OH)D concentrations less than 50 nmol/L were randomized to receive either 1000 IU or 400 IU per day of oral vitamin D3 supplementation from age 1 to 12 months. Infants with 25(OH)D concentrations of 50 nmol/L or greater formed a reference group.

MAIN OUTCOMES AND MEASURES

Measures at age 1, 3, 6, and 12 months were preplanned and included whole-body bone mineral content, lumbar spine bone mineral content, and bone mineral density using dual-energy x-ray absorptiometry, and serum 25(OH)D3 using liquid chromatography tandem mass spectrometry.

RESULTS

Of 139 included infants, 81 (58.3%) were male, and the median (IQR) gestational age at birth was 39.6 (38.9-40.6) weeks. A total of 49 infants were included in the 1000 IU per day group, 49 infants in the 400 IU per day group, and 41 in the reference group. Mean (SD) whole-body bone mineral content was not different between trial groups over time (1000 IU per day, 173.09 [2.36] g; 400 IU per day, 165.94 [66.08] g). Similarly, no differences were observed in lumbar spine bone mineral content or density. Mean (SD) serum 25(OH)D3 concentrations were significantly higher in the 1000 IU per day group from age 3 to 12 months (3 months, 115.2 [35.3] nmol/L; 6 months, 121.6 [34.4] nmol/L; 12 months, 99.6 [28.8] nmol/L) compared with the 400 IU per day trial group (3 months, 77.4 [23.3] nmol/L; 6 months, 85.1 [18.6] nmol/L; 12 months, 82.3 [14.3] nmol/L).

CONCLUSIONS AND RELEVANCE

In this study, a higher dose of vitamin D supplementation in infants born with 25(OH)D concentrations less than 50 nmol/L did not present advantages to bone mass in infancy. This study supports a standard dose of 400 IU per day of vitamin D supplementation for breastfed infants in Montreal.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02563015.

Vitamin D Status of Infants of Mothers with Gestational Diabetes: Status at Birth and a Randomized Controlled Trial of Vitamin D Supplementation across Infancy

BACKGROUND

Vitamin D status and requirements of infants of women with gestational diabetes mellitus (GDM) are unclear.

OBJECTIVES

The objectives were to assess vitamin D status in infants of mothers with GDM and compare vitamin D status in response to 400 vs. 1000 IU/d vitamin D supplementation in infants born with serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/L.

METHODS

Women with GDM delivering full-term infants (n = 98; March 2017-2019, Montreal, Canada) were surveyed for demographic and lifestyle factors. Pregnancy history was obtained from medical records. Newborn serum 25(OH)D was measured (immunoassay) and categorized as <30 (deficient) or ≥40 nmol/L (adequate). Breastfed neonates (n = 16) with serum 25(OH)D <50 nmol/L at birth were randomly assigned to 400 or 1000 IU/d of supplemental cholecalciferol (vitamin D3), and serum 25(OH)D was measured at baseline (≤1 mo) and 3, 6, and 12 mo of age. Groups were compared using a linear mixed-effects model and Tukey-Kramer post hoc tests.

RESULTS

Mean newborn serum 25(OH)D was 46.4 (95% CI: 43.9, 49.9) nmol/L, with 15.3% (95% CI: 8.2%, 22.4%) <30 nmol/L and 61.2% (95% CI: 51.6%, 70.9%) ≥40 nmol/L. During the trial, most infants were breastfed to 3 mo (400 IU/d: 87.5%; 1000 IU/d: 75.0%). Mean (± SEM) infant serum 25(OH)D was higher in the 1000-IU/d group at 3 mo (79.9 ± 5.9 vs. 111.5 ± 15.2 nmol/L; P = 0.0263), and although not different at 6-12 mo, was maintained at >50 nmol/L.

CONCLUSIONS

Most infants of women with GDM had adequate vitamin D status in this study. In those born with serum 25(OH)D <50 nmol/L, vitamin D status was corrected by 3 mo of age in response to 400 or 1000 IU/d of supplemental vitamin D. Dietary guidance should continue to recommend that all women who could become pregnant take a multivitamin supplement and that breastfed infants receive 400 IU/d of supplemental vitamin D. This study and ancillary trial were registered at clinicaltrials.gov (https://www.

CLINICALTRIALS

gov/ct2/show/NCT02563015) as NCT02563015.

Correction of neonatal vitamin D status using 1000 IU vitamin D/d increased lean body mass by 12 months of age compared with 400 IU/d: a randomized controlled trial

BACKGROUND

Intrauterine exposure to maternal vitamin D status <50 nmol/L of serum 25-hydroxyvitamin D [25(OH)D] may adversely affect infant body composition. Whether postnatal interventions can reprogram for a leaner body phenotype is unknown.

OBJECTIVES

The primary objective was to test whether 1000 IU/d of supplemental vitamin D (compared with 400 IU/d) improves lean mass in infants born with serum 25(OH)D <50 nmol/L.

METHODS

Healthy, term, breastfed infants (Montréal, Canada, March 2016-2019) were assessed for serum 25(OH)D (immunoassay) 24-36 h postpartum. Infants with serum 25(OH)D <50nmol/L at 24-36 h were eligible for the trial and randomly assigned at baseline (1 mo postpartum) to 400 (29 males, 20 females) or 1000 IU/d (29 males, 20 females) of vitamin D until 12 mo. Infants (23 males, 18 females) with 25(OH)D ≥50 nmol/L (sufficient) formed a nonrandomized reference group provided 400 IU/d. Anthropometry, body composition (DXA), and serum 25(OH)D concentrations were measured at 1, 3, 6, and 12 mo.

RESULTS

At baseline, mean ± SD serum 25(OH)D concentrations in infants allocated to the 400 and 1000 IU/d vitamin D groups were 45.8 ± 14.1 and 47.6 ± 13.4, respectively; for the reference group it was 69.2 ± 16.4 nmol/L. Serum 25(OH)D concentration increased on average to ≥50 nmol/L in the trial groups at 3-12 mo. Lean mass varied differently between groups over time; at 12 mo it was higher in the 1000 IU/d vitamin D group than in the 400 IU/d group (mean ± SD: 7013 ± 904.6 compared with 6690.4 ± 1121.7 g, P = 0.0428), but not the reference group (mean ± SD: 6715.1 ± 784.6 g, P = 0.19). Whole-body fat mass was not different between the groups over time.

CONCLUSIONS

Vitamin D supplementation (400 or 1000 IU/d) during infancy readily corrects vitamin D status, whereas 1000 IU/d modestly increases lean mass by 12 mo. The long-term implications require further research. This trial was registered at clinicaltrials.gov as NCT02563015.

Maternal excess adiposity and serum 25-hydroxyvitamin D < 50 nmol/L are associated with elevated whole body fat mass in healthy breastfed neonates

BACKGROUND

Vitamin D status of pregnant women is associated with body composition of the offspring. The objective of this study was to assess whether the association between maternal vitamin D status and neonatal adiposity is modified by maternal adiposity preconception.

METHODS

Healthy mothers and their term appropriate weight for gestational age (AGA) infants (n = 142; 59% male, Greater Montreal, March 2016-2019) were studied at birth and 1 month postpartum (2-6 weeks). Newborn (24-36 h) serum was collected to measure total 25-hydroxyvitamin D [25(OH)D] (immunoassay); maternal pre-pregnancy BMI was obtained from the medical record. Anthropometry, body composition (dual-energy X-ray absorptiometry) and serum 25(OH)D were measured at 2-6 weeks postpartum in mothers and infants. Mothers were grouped into 4 categories based on their vitamin D status (sufficient 25(OH)D ≥ 50 nmol/L vs. at risk of being insufficient < 50 nmol/L) and pre-pregnancy BMI (< 25 vs. ≥25 kg/m2): insufficient-recommended weight (I-RW, n = 24); insufficient-overweight/obese (I-OW/O, n = 21); sufficient-recommended weight (S-RW, n = 69); and sufficient-overweight/obese (S-OW/O, n = 28). Partial correlation and linear fixed effects model were used while adjusting for covariates.

RESULTS

At birth, infant serum 25(OH)D mean concentrations were below 50 nmol/L, the cut-point for sufficiency, for both maternal pre-pregnancy BMI categories; 47.8 [95%CI: 43.8, 51.9] nmol/L if BMI < 25 kg/m2 and 38.1 [95%CI: 33.5, 42.7] nmol/L if BMI ≥25 kg/m2. Infant serum 25(OH)D concentrations at birth (r = 0.77; P < 0.0001) and 1 month (r = 0.59, P < 0.0001) were positively correlated with maternal postpartum serum 25(OH)D concentrations. Maternal serum 25(OH)D concentration was weakly correlated with maternal percent whole body fat mass (r = - 0.26, P = 0.002). Infants of mothers in I-OW/O had higher fat mass versus those of mothers in S-OW/O (914.0 [95%CI: 766.4, 1061.6] vs. 780.7 [95%CI: 659.3, 902.0] g; effect size [Hedges' g: 0.42]; P = 0.04 adjusting for covariates) with magnitude of difference of 220.4 g or ~ 28% difference.

CONCLUSIONS

Maternal and neonatal vitamin D status are positively correlated. In this study, maternal adiposity and serum 25(OH)D < 50 nmol/L are dual exposures for neonatal adiposity. These findings reinforce the importance of vitamin D supplementation early in infancy irrespective of vitamin D stores acquired in utero and maternal weight status.

Patterns of Bone Mineral Accretion and Sex Differences in Healthy Term Vitamin D Replete and Breastfed Infants From Montreal, Canada: Bone Mass Reference Data

Infancy is a period of rapid bone growth and mineral accretion; nonetheless, reference data remain scarce for this age group. The purpose of this report is to generate reference data for bone mass in breastfed vitamin D replete infants and investigate patterns of bone mineral accretion and sex differences. This is a secondary analysis from a double-blinded randomized controlled trial (NCT00381914). Healthy term breastfed (exclusively or mixed) infants were randomized to different doses of oral vitamin D supplementation (400-1600 IU/d) and followed prospectively from 1 to 12 mo. Plasma 25-hydroxyvitamin D (LC-MS/MS), bone mineral content (BMC; whole body (WB) and lumbar spine (LS)) and bone mineral density (BMD; LS) were measured at 1, 3, 6, 9, and 12 mo by dual-energy x-ray absorptiometry (Hologic Discovery 4500A) with no effect of supplementation on bone outcomes. For the purpose of this analysis, 63 infants with adequate plasma 25-hydroxyvitamin D ≥ 50 nmol/L at baseline, were included. Differences over time and between sexes were tested using mixed model repeated measures ANOVA. Infants (31 males, 32 females) were 39.5 ± 1.1 wk gestational age at birth and appropriate for gestational age. WB BMC, LS BMC, and LS BMD increased by 143.2%, 116.8%, and 31.1% respectively across infancy. WB BMC was higher (4.2% - 9.4%; p = 0.03) in males than in females across the study. After adjusting WB BMC for weight, length or head BMC, sex differences were not evident. LS BMC and LS BMD did not vary by sex. LS BMD growth charts for both sexes combined, were generated using LMS chartmaker. WB BMC more than doubles during the first year of life confirming the importance of skeletal growth and the need for age-specific reference data in infancy. Sex differences in BMC, if any, are mostly driven by differences in body size.

No Sex Differences in Bone Mineral Accretion From 1 to 12 Months of Age Among a Sample of Healthy Term Breastfed Infants From Montreal, Canada

Objectives

To investigate sex differences in bone mass including whole body (WB) bone mineral content (BMC), lumbar spine (LS) BMC and LS bone mineral density (BMD) during infancy.

Methods

This is a secondary analysis of data from a double-blinded randomized clinical trial (NCT00381914), in which healthy term breastfed infants were randomized to 1 of 4 doses of oral vitamin D supplementation (400−1600 IU/d) at 1 mo of age (+/− 2 wk). Serum 25-hydroxyvitamin D (25(OH)D) using liquid chromatography-tandem mass spectrometry, and BMC and BMD using dual-energy x-ray absorptiometry (Hologic) were measured at 1, 3, 6, 9, and 12 mo of age (+/- 2 wk). No effect of supplementation on BMC (WB and LS) and BMD (LS) was reported in the primary study. Infants (32 males (M), 31 females (F)) with baseline serum 25(OH)D ≥ 50 nmol/L, based on the Institute of Medicine's cutoff in support of bone health, were included in this secondary analysis. Differences between sexes over time in BMC and BMD were tested using mixed model repeated measures ANOVA accounting for the fixed effects of sex, time, and sex*time and the random effect of infant ID, with Tukey multiple comparison test.

Results

Infants were on average 39.5 ± 1.1 wk gestational age, with weight for age z-score of 0.40 ± 0.97 at birth. There were no differences between sexes in mineral accretion rates of the WB (M: 12.94 ± 8.83, F: 12.20 ± 7.71 g/mo; p = 0.36) and at the LS (M: 0.26 ± 0.28, F: 0.22 ± 0.31 g/mo; p = 0.33) between 1 to 12 mo of age, but M had higher overall WB BMC than F (166.16 ± 57.30 vs. 153.34 ± 50.06 g, p = 0.03). When adjusted for weight or length, no sex differences were observed over time in WB BMC per weight (M: 22.02 ± 2.29, F: 22.20 ± 2.27 g/kg; p = 0.58) and WB BMC per length (M: 2.47 ± 0.60, F: 2.34 ± 0.53 g/cm, p = 0.06). Similarly, when using the WB less head BMC measurement, no sex differences were observed (M: 84.80 ± 30.24, F: 78.41 ± 7.57 g; p = 0.07). In addition, LS BMC (M: 3.77 ± 1.34, F: 3.75 ± 0.22 g; p = 0.93) and LS BMD (M: 0.273 ± 0.051, F: 0.284 ± 0.054 g/m2; p = 0.10) did not vary by sex.

Conclusions

Sex differences in BMC in infancy, if any, are mostly driven by infant size. Based on BMC and accretion rates, sex-specific normative data do not appear required during infancy.

Funding Sources

Canadian Institutes of Health Research, Nutricia Research Foundation, and the Canadian Foundation for Innovation.

Insufficient Vitamin D Status at Birth Is Corrected by Vitamin D Supplementation (1000 IU/Day) With Increases in Lean Mass Evident at 12 Months of Age in Healthy Term Infants

Objectives

The primary objective was to test whether rapid correction of insufficient vitamin D status initiated in the neonatal period improves whole-body lean mass across infancy.

Methods

This was a double-blinded, parallel-group, randomized controlled trial (NCT02563015). Healthy term breastfed infants of appropriate weight for gestational age (AGA) were recruited from Montreal (March 2016–2019). Capillary blood was collected (24–36 h) for serum 25-hydroxyvitamin D [25(OH)D] measurement (Liaison, Diasorin Inc.). Infants with serum 25(OH)D &lt; 50 nmol/L were randomized to receive 400 (group 1, n = 49) or 1000 IU/d (group 2, n = 49) until 12 mo of age. Those with 25(OH)D ≥ 50 nmol/L were recruited to form a reference group, receiving 400 IU/d (group 3, n = 41). Anthropometry, body composition (dual-energy x-ray absorptiometry), and 25(OH)D concentrations were assessed at 1, 3, 6, and 12 mo. Differences between trial and reference groups were tested using mixed model repeated measures ANOVA adjusting for maternal pregnancy weight gain, infant sex, skin color, actual age at assessment, and breastfeeding status. Data are mean ± SD.

Results

Infants (81 males, 58 females) were 39.6 ± 1.0 wk GA and 3388 ± 372 g at birth. By design, infants in group 1 and 2 had lower serum 25(OH)D concentrations at birth compared to group 3 (31.1 ± 9.3, 34.4 ± 12.0 vs. 68.0 ± 13.2 nmol/L, respectively, P &lt; 0.0001). On average, both trial groups achieved and maintained vitamin D sufficiency (25(OH)D ≥ 50 nmol/L) from 3 to 12 mo. Lean mass was not different among groups at baseline, but at 12 mo was higher in group 2 compared to group 1 (7012.5 ± 904.6 vs. 6690.4 ± 1121.7 g, P = 0.0075; 4.8% difference), and not different from the reference group (7012.5 ± 904.6 vs. 6715.1 ± 784.6 g, P = 0.2882). Weight, length, and whole-body fat mass were not different among groups at any time-point.

Conclusions

Vitamin D supplementation (400 and 1000 IU/d) corrects insufficient stores, whereas the higher dosage of 1000 IU/d, modestly increases lean mass of otherwise healthy AGA term born infants by 12 mo of age without altering weight or length. These data concur with observations in weanling rats where increased vitamin D intakes elevated lean mass. The long-term benefits require further research.

Funding Sources

Funded by Canadian Institutes of Health Research.

Normative Data for Lean Mass and Fat Mass in Healthy Predominantly Breast-Fed Term Infants From 1 Month to 1 Year of Age

BACKGROUND

A leaner body phenotype in infancy plays an important role in the early life prevention of obesity. However, there is a dearth of reference data for body composition in infancy. This study aimed to create a normative reference dataset for lean (LM) and fat (FM) mass and accretion rates in healthy infants.

METHODS

Healthy term-born infants (35 boys; 35 girls) were studied at ≤ 1, 3, 6, 9, and 12 mo of age for growth and compared to World Health Organization standards. LM (g) and FM (g) were measured using DXA (APEX version 13.3:3, Hologic 4500A) in infant whole-body mode. Sex specific reference curves were generated using the LMS method (LMSchartmaker, Medical Research Council, UK).

RESULTS

Infants were predominantly white (82.9%), breastfed (98.4% ≥ 3 mo), and grew in length and weight within World Health Organization Z-score ranges for normal growth across infancy. LM accretion was 327.4 ± 12.5 g/mo representing 95% increment in LM. Boys had more LM compared to girls at 12 mo (7807.4 ± 1114.0 vs 6817.4 ± 1016.1 g; p = 0.008). FM accretion was 114.3 ± 12.0 g/mo representing 114% increment in FM with no difference between the sexes.

CONCLUSIONS

This data, which is based on a healthy sample of infants, characterizes LM and FM accretion during the first year of life and will aid in the interpretation of body composition.

Ethnicity and Immigration Status as Risk Factors for Gestational Diabetes Mellitus, Anemia and Pregnancy Outcomes Among Food Insecure Women Attending the Montreal Diet Dispensary Program

OBJECTIVE

The primary aim of this study was to characterize the rate of adverse pregnancy outcomes in a multicultural group of low-income women.

METHODS

Data were extracted from the Montreal Diet Dispensary's database between June 2013 and December 2015. Risk was evaluated using logistic regression adjusted for covariates.

RESULTS

Of the 1,387 pregnancies, the prevalence of gestational diabetes mellitus (GDM) was 17.2% (95% confidence interval [CI], 15.1% to 19.3%), maternal anemia 44.9% (95% CI, 41.9% to 47.9%) and hypertension 3.8% (95% CI, 2.8% to 4.8%). The prevalence of small-for-gestational-age infants was 5.5% (95% CI, 4.3% to 6.7%), preterm births 4.7% (95% CI, 3.6% to 5.9%), low birthweight 4.2% (95% CI, 3.1% to 5.2%) and large-for-gestational-age infants was 10.6% (95% CI, 9.0% to 12.2%). Asian women had an increased odds of gestational diabetes mellitus (adjusted odds ratio [aOR], 1.86; 95% CI, 1.17 to 2.98) and SGA infants (aOR, 2.35; 95% CI 1.21 to 4.57) compared with white women. Anemia was more likely for black women compared with white women (aOR, 1.74; 95% CI, 1.29 to 2.35). Black women were more at risk of preterm birth (aOR, 1.79; 95% CI, 1.01 to 3.19). Immigrants showed an increased risk of maternal anemia compared with Canadian-born women (aOR, 1.85; 95% CI, 1.06 to 3.21).

CONCLUSIONS

As disparities in maternal and infant outcomes were present, nutritional intervention(s) need to be targeted toward prevention of adverse pregnancy outcomes, prioritization of higher-risk groups and adaptation of the program to a multiethnic low-income population.

Effects of Milk and Milk-Product Consumption on Growth among Children and Adolescents Aged 6-18 Years: A Meta-Analysis of Randomized Controlled Trials

Although studies have suggested that milk and milk-product consumption may influence growth during childhood and puberty, results are inconsistent. This meta-analysis was performed to evaluate the available evidence of randomized controlled trials (RCTs) assessing whether milk and milk-product consumption could affect growth and body composition among children and adolescents aged 6-18 y. PubMed, EMBASE, Web of Science, and The Cochrane Library databases were systematically searched for all RCTs published up to December 2017 that investigated milk and milk-product consumption (≥12 wk) on growth and body composition among participants (aged 6-18 y) without undernourishment or diseases. Study screening and data extraction by 2 reviewers followed established PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The Cochrane Collaboration's tool was used to assess the quality of the trials. Data were pooled using a random-effects model. Seventeen trials with 2844 children and adolescents were included. Milk and milk-product interventions resulted in a greater increase in body weight (0.48 kg; 95% CI: 0.19, 0.76 kg; P  =  0.001), lean mass (0.21 kg; 95% CI: 0.01, 0.41 kg; P  = 0.04), and attenuated gain in percentage body fat (-0.27%; 95% CI: -0.45%, -0.09%; P  = 0.003) compared with control groups. However, there were no significant changes in fat mass, height, or waist circumference in the intervention groups compared with the control groups (P ≥ 0.05). In subgroup analyses, the baseline weight and age, and the duration of intervention were associated with the efficacy of milk and milk-product intake on the change in lean mass, percentage body fat, and waist circumference, respectively (test for subgroup differences: P < 0.05). Children and adolescents aged 6-18 y consuming milk and milk products are more likely to achieve a lean body phenotype. This meta-analysis was registered in the International Prospective Register of Systematic Reviews (PROSPERO) as CRD42018086850.

Maternal risk factors and newborn infant vitamin D status: a scoping literature review

Low vitamin D (VitD) status is common among newborn infants, more so in temperate latitudes with evidence that maternal VitD deficiency is a major risk factor given that the neonate relies solely on maternal-fetal transfer of VitD. This scoping review was conducted to provide an overview of the latest evidence from studies regarding the impact of maternal risk factors on infant 25-hydryoxyvitamin D [25(OH)D] concentrations with a focus on studies in Canada and the United States. Several maternal risk factors that contribute to low maternal-fetal 25(OH)D concentrations have been reported over many decades, but no clear pattern has been established for multiethnic populations. For example, darker skin pigmentation and ethnicity are common risk factors for low VitD status. Studies in predominantly white women showed that supplementation of VitD during pregnancy causes significant increases in maternal serum 25(OH)D which often improves cord serum 25(OH)D values. In addition, VitD recommendations by health care professionals and adherence to supplementation by pregnant women appear to positively influence maternal and infant 25(OH)D concentrations. Conversely, winter season, obesity, lower socioeconomic status including lifestyle factors (smoking), and use of medication pose risk for lower maternal-fetal transfer of VitD. However, there is still a dearth of pertinent data on the relationship between some of the maternal risk factors and newborn 25(OH)D concentrations, for instance, relationships between gestational diabetes and neonatal VitD status. Additional research is required to determine if the same target for 25(OH)D concentrations applies for pregnant women, neonates, and infants.

Socio-Demographic and Lifestyle Factors Predict 5-Year Changes in Adiposity among a Group of Black South African Adults

The rising prevalence of obesity and excessive adiposity are global public health concerns. Understanding determinants of changes in adiposity over time is critical for informing effective evidence-based prevention or treatment. However, limited information is available to achieve this objective. Cultural, demographic, environmental, and behavioral factors including socio-economic status (SES) likely account for obesity development. To this end, we related these variables to anthropometric measures in 1058 black adult Tswana-speaking South Africans who were HIV negative in a prospective study over five years. Body mass index (BMI) and waist circumference increased in both sexes, whereas triceps skinfold thickness remained the same. Over the five years, women moved to higher BMI categories and more were diagnosed with central obesity. Age correlated negatively, whereas SES, physical activity, energy, and fat intake correlated positively with adiposity markers in women. In men, SES, marital status, physical activity, and being urban predicted increases in adiposity. For women, SES and urbanicity increased, whereas menopause and smoking decreased adiposity. Among men, smokers had less change in BMI than those that never smoked over five years. Our findings suggest that interventions, focusing on the urban living, the married and those with the highest SES-the high-risk groups identified herein-are of primary importance to contain morbidity and premature mortality due to obesity in black South Africans.

Lean Mass Appears to Be More Strongly Associated with Bone Health than Fat Mass in Urban Black South African Women

OBJECTIVES

To examine the association between body composition (fat mass, lean mass and body mass index, BMI) and bone health (bone mineral density, BMD and fracture risk) in urban black South African women.

DESIGN

A cross sectional study examining associations between body composition, dietary intake (food frequency questionnaire), habitual physical activity (Activity energy expenditure (AEE) measured using an accelerometer with combined heart rate monitor and physical activity questionnaire) and bone health (BMD using dual-energy X ray absorptiometry, DXA and fracture risk).

SETTING

Urban community dwellers from Ikageng in the North-West Province of South Africa.

PARTICIPANTS

One hundred and eighty nine (189) healthy postmenopausal women aged ≥43 years.

RESULTS

Fat mass and lean mass were significantly associated with BMD and fracture risk when adjusted for potential confounders. However, lean mass and not fat mass remained significantly associated with femoral neck BMD (β = 0.49, p <0.001), spine BMD (β = 0.48, p< 0.0001) and hip BMD (β = 0.59, p< 0.0001). Lean mass was also negatively associated with fracture risk (β = -0.19 p =0.04) when both lean and fat mass were in the same model.

CONCLUSION

Lean mass and fat mass were positively associated with femoral neck, spine and hip BMDs and negatively associated with fracture risk in urban black South African women. Our finding suggests that increasing lean mass rather than fat mass is beneficial to bone health. Our study emphasises the importance of positive lifestyle changes, intake of calcium from dairy and adequate weight to maintain and improve bone health of postmenopausal women.