Yankuba Sawo

Effect of calcium supplementation in pregnancy on maternal bone outcomes in women with a low calcium intake

Background: Mobilization of maternal bone mineral partly supplies calcium for fetal and neonatal bone growth and development. Objective: We investigated whether pregnant women with low calcium intakes may have a more extensive skeletal response postpartum that may compromise their short- or long-term bone health. Design: In a subset of participants (n = 125) in a double-blind, randomized, placebo-controlled trial (International Trial Registry: ISRCTN96502494) in pregnant women in The Gambia, West Africa, with low calcium intakes (≈350 mg Ca/d), we measured bone mineral status of the whole body, lumbar spine, and hip by using dual-energy X-ray absorptiometry and measured bone mineral status of the forearm by using single-photon absorptiometry at 2, 13, and 52 wk lactation. We collected blood and urine from the subjects at 20 wk gestation and at 13 wk postpartum. Participants received calcium carbonate (1500 mg Ca/d) or a matching placebo from 20 wk gestation to parturition; participants did not consume supplements during lactation. Results: Women who received the calcium supplement in pregnancy had significantly lower bone mineral content (BMC), bone area (BA), and bone mineral density (BMD) at the hip throughout 12 mo lactation (mean ± SE difference: BMC = −10.7 ± 3.7%, P = 0.005; BA = −3.8 ± 1.9%, P = 0.05; BMD = −6.9 ± 2.6%, P = 0.01). The women also experienced greater decreases in bone mineral during lactation at the lumbar spine and distal radius and had biochemical changes consistent with greater bone mineral mobilization. Conclusions: Calcium supplementation in pregnant women with low calcium intakes may disrupt metabolic adaptation and may not benefit maternal bone health. Further study is required to determine if such effects persist long term or elicit compensatory changes in bone structure.

The effect of prepubertal calcium carbonate supplementation on the age of peak height velocity in Gambian adolescents

Background: Limited evidence suggests that calcium intake before puberty influences adolescent height growth and the timing of puberty. Such an effect might be particularly marked in populations in whom low calcium intake, stunting, and delayed puberty are common. Objective: The objective was to test whether 12 mo of calcium supplementation at age 8–12 y to increase intakes toward international recommendations had long-term effects on adolescent growth and pubertal development in rural Gambian children. Design: This was a longitudinal study of 160 Gambian boys (n = 80) and girls (n = 80) who had participated in a 12-mo, randomized, double-blind, placebo-controlled, calcium carbonate supplementation trial (1000 mg Ca/d, 5 d/wk) at age 8–12 y. Anthropometric measures were made every 1–2 y until age 21–25 y; pubertal status and menarche data were collected. Repeated-measures ANCOVA and Superimposition by Translation and Rotation Method (SITAR) growth models were used to assess the effects of treatment. Results: In boys, midadolescent height growth was advanced in the calcium group, which resulted in greater stature at a mean age of 15.5 y (mean ± SEM: 2.0 ± 0.8 cm; P = 0.01) and an earlier age of peak height velocity by 7.4 ± 2.9 mo. Subsequently, the calcium group stopped growing earlier (P = 0.02) and was 3.5 ± 1.1 cm shorter (P = 0.002) at a mean age of 23.5 y. Weight and midupper arm circumference paralleled height. No significant effects were observed in girls, but a sex-by-supplement interaction on height growth could not be confirmed. Conclusion: Calcium supplementation of boys in late childhood advanced the age of peak height velocity and resulted in shorter adult stature in a population in whom low calcium intakes and delayed puberty are common. This trial was registered at isrctn.org as ISRCTN28836000.

Nutritional supplementation during pregnancy and offspring cardiovascular disease risk in The Gambia.

BACKGROUND Maternal nutritional intake during pregnancy may have important consequences for long-term health in offspring. OBJECTIVE The objective was to follow up the offspring in 2 randomized trials of nutrient supplementation during pregnancy to investigate the effect on cardiovascular disease (CVD) risk in offspring. DESIGN We recruited offspring born during 2 trials in The Gambia, West Africa. One trial provided protein-energy-dense food supplements (1015 kcal and 22 g protein/d) to pregnant (intervention, from 20 wk gestation until delivery) or lactating (control, for 20 wk from birth) women and was randomized at the village level. The second was a double-blind, individually randomized, placebo-controlled trial of calcium supplementation (1.5 g/d), which was also provided from 20 wk gestation until delivery. RESULTS Sixty-two percent (n = 1267) of children (aged 11-17 y) born during the protein-energy trial were recruited and included in the analysis, and 64% (n = 350) of children (aged 5-10 y) born during the calcium trial were recruited and included in the analysis. Fasted plasma glucose was marginally lower in children born to mothers receiving protein-energy supplements during pregnancy than in those children of the lactating group (adjusted mean difference: -0.05 mmol/L; 95% CI: -0.10, -0.001 mmol/L). There were no other differences in CVD risk factors, including blood pressure, body composition, and cholesterol, between children born to intervention and control women from the protein-energy trial. Maternal calcium supplementation during pregnancy was unrelated to offspring blood pressure. CONCLUSION These data suggest that providing supplements to pregnant women in the second half of pregnancy may have little effect on the CVD risk of their offspring, at least in this setting and at the ages studied here. This trial was registered at www.controlled-trials.com as ISRCTN96502494.

Effect of maternal calcium supplementation on offspring blood pressure in 5- to 10-y-old rural Gambian children.

Background: Evidence suggests that increased maternal calcium intake during pregnancy may result in lower offspring blood pressure, prompting calls for more robust data in this field, particularly in settings of habitually low calcium intake. Objective: The objective was to investigate the effect of maternal calcium supplementation on blood pressure in offspring by recruiting children born after a randomized, double-blind, placebo-controlled trial of calcium supplementation during pregnancy. Design: Children (n = 389) from a rural area of The Gambia (mean age: 7.4 ± 1.2 y; range: 5–10 y), whose mothers received a calcium supplement (1500 mg Ca/d from 20 wk of gestation until delivery) or placebo, were followed up in West Africa. Blood pressure was assessed under standardized conditions with use of the Omron 705IT automated oscillometric device (Morton Medical Ltd, London, United Kingdom), and anthropometric and body composition (bioelectrical impedance) measurements were also made. Results: The analysis was restricted to 350 children born at term, which represented 64% of original trial births. There was no difference in systolic (adjusted mean difference: −0.04 mm Hg; 95% CI: −1.78, 1.69 mm Hg) or diastolic (adjusted mean difference: 0.25 mm Hg; 95% CI: −1.27, 1.77 mm Hg) blood pressure between children whose mothers had received calcium and those who received placebo. No interaction between childhood body mass index (in kg/m2; mean: 14.0) and maternal calcium supplementation was observed in this study. Conclusion: Calcium supplementation in the second half of pregnancy in Gambian women with very low habitual calcium intakes may not result in lower offspring blood pressure at 5–10 y of age.

Unexpected long-term effects of calcium supplementation in pregnancy on maternal bone outcomes in women with a low calcium intake: a follow-up study

Background: Calcium supplementation of pregnant Gambian women with a low calcium intake results in lower maternal bone mineral content in the subsequent lactation. Objective: The objective was to investigate whether the lower bone mineral content persists long term. Design: All women in the calcium supplementation trial (International Trial Registry ISRCTN96502494) who had been scanned with dual-energy X-ray absorptiometry at 52 wk of lactation (L52; n = 79) were invited for follow-up when neither pregnant nor lactating for ≥3 mo (NPNL) or at 52 wk postpartum in a future lactation (F52). Bone scans and anthropometric and dietary assessments were conducted. Results: Sixty-eight women participated (35 at both NPNL and F52 and 33 at only one time point): n = 59 NPNL (n = 31 calcium, n = 28 placebo) and n = 44 F52 (n = 24 calcium, n = 20 placebo). The mean (±SD) time from L52 was 4.9 ± 1.9 y for NPNL and 5.0 ± 1.3 y for F52. Size-adjusted bone mineral content (SA-BMC) was greater at NPNL than at L52 in the placebo group (P ≤ 0.001) but not in the calcium group (P for time-by-group interaction: lumbar spine, 0.002; total hip, 0.03; whole body, 0.03). No significant changes in SA-BMC from L52 to F52 were observed in either group. Consequently, the lower SA-BMC in the calcium group at L52 persisted at NPNL and F52 (P ≤ 0.001): NPNL (lumbar spine, −7.5 ± 0.7%; total hip, −10.5 ± 1.0%; whole body, −3.6 ± 0.5%) and F52 (lumbar spine, −6.2 ± 0.9%; total hip, −10.3 ± 1.4%; whole body, −3.2 ± 0.6%). Conclusion: In rural Gambian women with a low-calcium diet, a calcium supplement of 1500 mg/d during pregnancy resulted in lower maternal bone mineral content in the subsequent lactation that persisted long term. This trial was registered at www/controlled-trials.com/mrct/ as ISRCTN96502494.

The Effect of Prepubertal Calcium Carbonate Supplementation on Skeletal Development in Gambian Boys—A 12-Year Follow-Up Study

CONTEXT Calcium intake during growth is essential for future bone health but varies widely between individuals and populations. The impact on bone of increasing calcium intake is unknown in a population where low calcium intake, stunting, and delayed puberty are common. OBJECTIVE To determine the effect of prepubertal calcium supplementation on mean age at peak velocity for bone growth and mineral accrual. DESIGN AND SETTING Prospective follow-up of boys in rural Gambia, West Africa, who had participated in a double-blind, randomized, placebo-controlled trial of calcium supplementation. PARTICIPANTS Eighty boys, initially aged 8.0-11.9 years, were followed up for 12 years. INTERVENTIONS Subjects received 1 year of calcium carbonate supplementation (1000 mg daily, 5 d/wk). MAIN OUTCOME MEASURES Dual-energy x-ray absorptiometry measurements were carried out for whole body (WB), lumbar spine, and total hip bone mineral content, bone area (BA), and WB lean mass. Super imposition by translation and rotation models was made to assess bone growth. RESULTS Age at peak velocity was consistently earlier in the calcium group compared to the placebo group, for WB bone mineral content (mean, -6.2 [SE, 3.1]; P = .05), WB BA (mean, -7.0 [SE, 3.2] mo; P = .03), lumbar spine and total hip BA. By young adulthood, supplementation did not change the amount of bone accrued (mineral or size) or the rate of bone growth. CONCLUSIONS Twelve months of prepubertal calcium carbonate supplementation in boys with a low calcium diet advanced the adolescent growth spurt but had no lasting effect on bone mineral or bone size. There is a need for caution when applying international recommendations to different populations.

The adolescent transition under energetic stress: Body composition tradeoffs among adolescent women in The Gambia.

Young female adolescents under energetic stress gain lean mass and lose fat mass while older adolescents lose lean mass and maintain fat. These findings support the prediction of life history theory that adolescence represents a period of transition from investment in growth to investment in reproduction.

Bone mineral changes after lactation in Gambian women accustomed to a low calcium intake.

BACKGROUND/OBJECTIVES:Previous studies in Gambian women with a low calcium intake have described decreases in whole-body and regional bone mineral content (BMC) and areal bone mineral density (aBMD) during the first year of lactation. The aim of this study was to examine whether these effects are reversed after lactation.SUBJECTS/METHODS:Thirty-three Gambian women who had a previous dual-energy X-ray absorptiometry (DXA) scan at 52 weeks lactation (L52) were invited to participate in a follow-up study when neither pregnant nor lactating (NPNL) for ⩾3 months and/or when 52 weeks postpartum in a subsequent lactation (F52). Whole body, lumbar spine and hip bone mineral were measured by DXA. Anthropometry and dietary assessments were also conducted. Repeated-measures analysis of covariance was used to determine differences from L52 at NPNL and F52.RESULTS:Twenty-eight women were scanned at NPNL and 20 at F52. The mean±s.d. calcium intake of the 33 women at NPNL and F52 was 360±168 mg/day. BMC, aBMD and size-adjusted BMC (SA-BMC) at all sites were higher at NPNL than L52. Percent increases in SA-BMC (mean±s.e.m.) were significant (P<0.0001): whole body=2.7±0.4%; lumbar spine=4.9±1.0%; total hip=3.7±1.0%. There were no significant differences in any measurements between the two lactation time points (L52 and F52).CONCLUSIONS:This study of Gambian women with low calcium intakes demonstrates that bone mineral mobilised during lactation is recovered after lactation. Successive periods of long lactation are not associated with progressive skeletal depletion.

The Gambian Bone and Muscle Ageing Study: Baseline Data from a Prospective Observational African Sub-Saharan Study

The Gambian Bone and Muscle Ageing Study is a prospective observational study investigating bone and muscle ageing in men and women from a poor, subsistence farming community of The Gambia, West Africa. Musculoskeletal diseases, including osteoporosis and sarcopenia, form a major part of the current global non-communicable disease burden. By 2050, the vast majority of the world’s ageing population will live in low- and middle-income countries with an estimated two-fold rise in osteoporotic fracture. The study design was to characterise change in bone and muscle outcomes and to identify possible preventative strategies for fracture and sarcopenia in the increasing ageing population. Men and women aged ≥40 years from the Kiang West region of The Gambia were recruited with stratified sampling by sex and age. Baseline measurements were completed in 488 participants in 2012 who were randomly assigned to follow-up between 1.5 and 2 years later. Follow-up measurements were performed on 465 participants approximately 1.7 years after baseline measurements. The data set comprises a wide range of measurements on bone, muscle strength, anthropometry, biochemistry, and dietary intake. Questionnaires were used to obtain information on health, lifestyle, musculoskeletal pain, and reproductive status. Baseline cross-sectional data show preliminary evidence for bone mineral density and muscle loss with age. Men had greater negative differences in total body lean mass with age than women following adjustments for body size. From peripheral quantitative computed tomography scans, greater negative associations between bone outcomes and age at the radius and tibia were shown in women than in men. Ultimately, the findings from The Gambian Bone and Muscle Ageing Study will contribute to the understanding of musculoskeletal health in a transitioning population and better characterise fracture and sarcopenia incidence in The Gambia with an aim to the development of preventative strategies against both.

Sexual Dimorphism in Bone and Body Composition in Rural Gambian Prepubertal Children Habituated to a Low Calcium Intake

Gender differences in bone during childhood and adolescence are well described in countries with moderate to high calcium intakes; there are few data from countries where children have delayed puberty and low habitual calcium intakes. The aim of this study was to determine whether gender differences in bone and body composition exist in prepubertal Gambian children accustomed to a low calcium intake.