Flavia F. Bezerra

Effect of calcium plus vitamin D supplementation during pregnancy in Brazilian adolescent mothers: a randomized, placebo-controlled trial

BACKGROUND Pregnancy and lactation in adolescents with habitually low calcium intake may adversely affect maternal bone mass. OBJECTIVE We investigated the effect of calcium plus vitamin D supplementation during pregnancy on bone mass during lactation in Brazilian adolescent mothers with low-calcium diets (∼600 mg/d). DESIGN Pregnant adolescents (14-19 y) randomly received daily calcium (600 mg) plus vitamin D3 (200 IU) (n = 30) or a placebo (n = 26) from 26 wk of pregnancy (baseline) until parturition. The bone mineral content (BMC), bone area (BA), and bone mineral density (BMD) at the total body, lumbar spine, and hip (total and femoral neck) were evaluated by using dual-energy X-ray absorptiometry at 5 and 20 wk postpartum. Serum hormones and 25-hydroxyvitamin D [25(OH)D] were measured. Group comparisons were adjusted for significant covariates. RESULTS The mean serum 25(OH)D concentration was 59 nmol/L at baseline. In comparison with the placebo, 25(OH)D tended to be 14-15 nmol/L higher postpartum in the supplemented group (P = 0.08). Total body and hip BMC and BMD decreased over time (P ≤ 0.005) in both groups with a group × time interaction at the femoral neck (P < 0.04). Supplemented mothers had higher lumbar spine BA (6.7%; P = 0.002) and lumbar spine BMC (7.9%, P = 0.08) than did mothers who consumed the placebo at 5 wk postpartum. At 20 wk postpartum, differences between groups were more evident, with higher lumbar spine BMC (13.9%), lumbar spine BA (6.2%), and lumbar spine BMD (10.6%) in the supplemented group (P ≤ 0.008). CONCLUSIONS Calcium plus vitamin D supplementation during pregnancy of adolescents with low calcium intake results in higher lumbar spine bone mass and a reduced rate of femoral neck bone loss during lactation. Additional studies are required to determine whether bone effects are temporary or long-lasting. This trial was registered at clinicaltrials.gov as NCT01732328.

Lead levels in erythrocytes and biomarkers of bone turnover in pregnant and lactating women with marginal calcium intakes

Abstract The purpose of this study was to compare erythrocyte lead levels and relationship with biomarkers of bone turnover in pregnant (n = 68, 28–39 weeks of gestation), lactating (n = 45, 1–2 months post-partum) and control (n = 33) adult women with habitually low calcium intake (400–600 mg Ca/d) and low environmental lead exposure (blood lead levels

Activation of Nrf2-Antioxidant Signaling by 1,25-Dihydroxycholecalciferol Prevents Leptin-Induced Oxidative Stress and Inflammation in Human Endothelial Cells

Background: Obesity is associated with hyperleptinemia and endothelial dysfunction. Hyperleptinemia has been reported to induce both oxidative stress and inflammation by increasing reactive oxygen species production.Objective: The objective of this study was to determine the effects of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] against leptin-induced oxidative stress and inflammation in human endothelial cells.Methods: Small interfering RNA (siRNA) were used to knock down the expression of vitamin D receptor (VDR) in human umbilical vein endothelial cells (HUVECs). HUVECs were pretreated for 4 h with physiologic (10-10 M) or supraphysiologic (10-7 M) concentrations of 1,25(OH)2D3 and exposed to leptin (10 ng/mL). Superoxide anion production and translocation of nuclear factor (erythroid-derived 2)-like 2 (NRF2) and nuclear transcription factor κB (NF-κB) subunit p65 to the nucleus and the activation of their target genes were quantified.Results: Pretreatment of HUVECs with 1,25(OH)2D3 prevented the leptin-induced increase in superoxide anion production (P < 0.05). Pretreatment with 1,25(OH)2D3 further increased NRF2 translocation to the nucleus (by 3-fold; P < 0.05) and increased mRNA expression of superoxide dismutase 2 (SOD2; by 2-fold), glutathione peroxidase (GPX; by 3-fold), NAD(P)H dehydrogenase (quinone) 1 (NQO1; by 4-fold), and heme oxygenase 1 (HMOX1; by 2-fold) (P < 0.05). Leptin doubled the translocation of NF-κB (P < 0.05) to the nucleus and increased (P < 0.05) the upregulation of vascular inflammatory mediators such as monocyte chemoattractant protein 1 (MCP1; by 1-fold), transforming growth factor β (TGF β by 1-fold), and vascular cell adhesion molecule 1 (VCAM1; by 4-fold) (P < 0.05), which were prevented (P < 0.05) by pretreatment with 1,25(OH)2D3 Protective effects of 1,25(OH)2D3 were confirmed to be VDR dependent by using VDR siRNA.Conclusion: Pretreatment with 1,25(OH)2D3 in the presence of a high concentration of leptin has a beneficial effect on HUVECs through the regulation of mediators of antioxidant activity and inflammation.

Calcium homeostasis in primiparae and multiparae pregnant women with marginal calcium intakes and response to a 7-day calcium supplementation trial

Among women with adequate calcium intakes, further increases in dietary or supplemental calcium do not alter the homeostatic response in calcium metabolism during pregnancy. Less is known about women consuming low calcium intakes and the influence of parity on calcium metabolism among women with low intakes. In this study we compared bone and renal indices of calcium homeostasis and response to a 7-day calcium supplementation trial (1000 mg/day) in non-pregnant women (n=31) and third-trimester pregnant women (primiparae, n=40, and multiparae, n=30) with habitual calcium intake of 400 mg/day. Markers of bone resorption (urinary hydroxyproline and D-pyridinoline) and of bone formation (activity in plasma of bone alkaline phosphatase) were substantially increased in the pregnant women consistent with increased bone turnover. Urinary hydroxyproline excretion was higher (24%) in primiparous than in multiparous pregnant women. Bone and renal indices responded to the supplementation trial in non-pregnants and pregnants with differences between primiparae and multiparae. Bone alkaline phosphatase activity increased (p<0.05) with supplementation in all groups; D-pyridinoline did not change in non-pregnants and primiparous pregnants but decreased (p<0.01) in pregnant multiparae. Urinary calcium increased (p<0.05), urinary phosphorous decreased (p<0.01) and hydroxyproline decreased (p<0.01) after supplementation in non-pregnants and pregnant primiparae but not in multiparae. Differences in bone and renal indices due to pregnancy were maintained after the supplementation trial in primiparae but not always in multiparae. Our results indicate that parity may accentuate the stress of pregnancy on calcium homeostasis in women with marginal calcium intakes. Follow-up long-term studies are needed to evaluate the effect of calcium supplementation and parity on bone mass in these women during pregnancy.

CHAPTER 29:Calcium Supplementation during Pregnancy and Lactation: Implications for Maternal and Infant Bone Health

It is well accepted that in women with calcium intakes close to current recommendations, the physiologic adaptations for providing calcium to the fetus and infant are largely independent of calcium intake, and that there is no apparent bone benefit for the mother or infant of using calcium supplements. However, in women consuming low calcium diets, and in adolescent mothers, maternal bone adaptations during reproduction have been found to respond to increased calcium intake or calcium supplementation although not always as expected. Moreover, fetal and infant skeletal development has been found to be positively associated to increased maternal calcium intake or supplementation during pregnancy in some but not all studies. These apparently inconsistent results are possibly due to the complex interactions between genetics, diet composition, calcium intake, environment, and lifestyle on maternal and infant bone responses during pregnancy and lactation. In this chapter, studies evaluating the effect of maternal calcium intake during pregnancy and lactation, from the diet and from supplements, on maternal bone outcomes and on fetal and infant bone growth are reviewed. The effect of other factors on bone outcomes and the possible implications for the maternal and infant bone health are considered.

SMOKING STATUS AFFECTS BIOIMPEDANCE-DERIVED PHASE ANGLE IN MEN BUT NOT IN WOMEN: THE PRÓ-SAÚDE STUDY, BRAZIL

OBJECTIVE Phase angle (PhA) is determined by bioelectrical impedance (BIA) and it is interpreted as an index of cell membrane integrity. Smokers are susceptible to systemic oxidative stress and often adopt unhealthy habits, which may contribute to cellular damage. This unfavorable conjuncture may result in lower PhA in smokers. The aim of this study was to investigate the association between PhA and smoking status. METHODS This cross-sectional study included 247 (48%) adult men. Body composition and PhA were determined using dual-energy x-ray absorptiometry and BIA, respectively. Blood sampling, food habits, and smoking status information were collected. Statistical analyses were performed for each sex separately. Analysis of covariance controlling for body mass index and age compared PhA values across smoking categories. Multiple linear regression determined whether smoking status was a PhA predictor. RESULTS PhA was lower in male current smokers (6.6 ± 0.13°) compared with never-smokers (7 ± 0.06°; P = 0.038). The ratio of extracellular to intracellular water was higher in current (P = 0.003) and former male smokers (P = 0.006) compared with never-smokers. Body composition did not differ in male and female smoking categories. Male current smokers ingested more calories, protein, carbohydrates, and alcohol than never and former smokers (P < 0.05). Current female smokers had higher alcohol consumption compared with never smokers (P = 0.019). Male current smokers presented lower than never-smokers (unstandardized β coefficient = -0.202; 95% confidence interval, -0.359 to -0.046). Smoking status was associated with PhA decrease only in men. CONCLUSION The results from the present study suggest that being a current smoker results in lower PhA in men, even when controlling for other variables.