Maternal calcium metabolism and bone mineral status

Assessing breast arterial calcification in mammograms and its implications for atherosclerotic cardiovascular disease risk

PURPOSE

Breast arterial calcifications (BAC) are incidentally observed on mammograms, yet their implications remain unclear. We investigated lifestyle, reproductive, and cardiovascular determinants of BAC in women undergoing mammography screening. Further, we investigated the relationship between BAC, coronary arterial calcifications (CAC) and estimated 10-year atherosclerotic cardiovascular (ASCVD) risk.

METHODS

In this cross-sectional study, we obtained reproductive history and CVD risk factors from 215 women aged 18 or older who underwent mammography and cardiac computed tomographic angiography (CCTA) within a 2-year period between 2007 and 2017 at hospital. BAC was categorized as binary (present/absent) and semi-quantitatively (mild, moderate, severe). CAC was determined using the Agatston method and recorded as binary (present/absent). Adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated, accounting for age as a confounding factor. ASCVD risk over a 10-year period was calculated using the Pooled Cohort Risk Equations.

RESULTS

Older age, systolic and diastolic blood pressures, higher parity, and younger age at first birth (≤28 years) were significantly associated with greater odds of BAC. Women with both BAC and CAC had the highest estimated 10-year risk of ASCVD (13.30 %). Those with only BAC (8.80 %), only CAC (5.80 %), and no BAC or CAC (4.40 %) had lower estimated 10-year risks of ASCVD. No association was detected between presence of BAC and CAC.

CONCLUSIONS

These findings support the hypothesis that BAC on a screening mammogram may help to identify women at potentially increased risk of future cardiovascular disease without additional cost and radiation exposure.

The association between breast arterial calcification and atherosclerotic cardiovascular disease in an Australian population-based breast cancer case-control study

PURPOSE

Atherosclerotic cardiovascular disease (ASCVD) is a major cause of morbidity and mortality. Breast arterial calcification (BAC) on mammograms is not associated with breast cancer risk. However, there is increasing evidence supporting its association with cardiovascular disease (CVD). This study examines the association between BAC and ASCVD and their risk factors within an Australian population-based breast cancer study.

MATERIALS AND METHODS

Data from the controls who participated in the breast cancer environment and employment study (BCEES) were linked with the Western Australian Department of Health Hospital Morbidity database and Mortality Registry to obtain ASCVD outcomes and related risk factor data. Mammograms from participants with no prior history of ASCVD were assessed for BAC by a radiologist. Cox proportional hazards regression was used to examine the association between BAC and later occurrence of an ASCVD event. Logistic regression was used to investigate the factors associated with BAC.

RESULTS

A total of 1020 women with a mean age of 60 (sd = 7.0 years) were included and BAC found in 184 (18.0%). Eighty (7.8%) of the 1020 participants developed ASCVD, with an average time to event of 6.2 years (sd = 4.6) from baseline. In univariate analysis, participants with BAC were more likely to have an ASCVD event (HR = 1.96 95% CI 1.29-2.99). However, after adjusting for other risk factors, this association attenuated (HR = 1.37 95% CI 0.88-2.14). Increasing age (OR = 1.15, 95% CI 1.12-1.19) and parity (p_LRT < 0.001) were associated with BAC.

CONCLUSION

BAC is associated with increased ASCVD risk, but this is not independent of cardiovascular risk factors.

Reproductive factors and breast arterial calcification: a systematic review and meta-analysis

BACKGROUND

Breast arterial calcification (BAC) is a common incidental finding on screening mammography. Recent evidence suggests that BAC is associated with cardiovascular disease (CVD). We systematically reviewed the associations between BAC and reproductive factors (menopausal status, hormone replacement therapy [HRT] use, oral contraceptive [OC] use and parity).

METHODS

MEDLINE and EMBASE databases, references of relevant papers and Web of Science were searched up to February 2020 for English-language studies that evaluated these associations. Study quality were determined and a random effects model was used to assess these associations.

RESULTS

Nineteen observational studies (n = 47,249; three cohort studies, seven case-control studies, nine cross-sectional studies) were included. BAC was associated with menopause (nine studies; n = 15,870; odds ratio [OR] 2.67; 95% confidence interval [CI] 1.50-4.77) and parity (seven studies; n = 27,728; OR 2.50; 95% CI 1.68-3.71) and inversely with HRT use (10 studies; n = 33,156; OR 0.57; 95% CI 0.40-0.80). No association was found with OC use. Eleven studies were considered good in quality. Marked heterogeneity existed across all analyses.

CONCLUSIONS

BAC is associated with HRT use, menopause and parity. However, careful interpretation is required as marked heterogeneity existed across all analyses. Traditional cardiovascular risk factors may need to be taken into account in future investigations of associations between BAC and reproductive factors.

PROSPERO

CRD42020141644.

Dietary Choices of New Zealand Women during Pregnancy and Lactation

Dietary recommendations during pregnancy and lactation have become increasingly complex, and sources of information more numerous but not always reliable, potentially causing confusion and unsafe choices. Women were recruited during pregnancy or within six months postpartum and completed questionnaires on dietary choices, food safety, and sources of nutrition information. Women (n = 458) from around New Zealand participated in the study. They consumed a wide range of foods and beverages and reported various dietary changes. In pregnancy, women commonly avoided alcohol (92%), raw milk products (86%), and raw, smoked, or pre-cooked seafood and fish (84%), and made changes due to food safety concerns. Influential advice was acquired from a range of sources including midwives (37%) and the New Zealand pregnancy and breastfeeding guidelines (25%) during pregnancy. Food avoidance was less common in lactation. However, fewer women consumed milk products during lactation (64%) than pregnancy (93%). Potentially unreliable sources were used more frequently in lactation including alternative health practitioners (26%) and family or friends (12%), and dietary changes were often made in response to infant symptoms without supporting evidence. This study highlighted a need for good communication of evidence-based recommendations to women, especially during lactation.

Prevalence and correlates of low serum calcium in late pregnancy: A cross sectional study in the Nkongsamba Regional Hospital; Littoral Region of Cameroon

INTRODUCTION

Women from low and middle income countries are generally more likely to have sub-optimal calcium intake. The objective of this study was to assess serum calcium disorders and correlates in late pregnancy.

METHODS

We conducted from December 2018 to April 2019, a cross-sectional hospital-based study targeting pregnant women in late pregnancy in the Nkongsamba Regional Hospital. Data were collected by measurement of parameters (weight, height, blood pressure and foetal birthweight), administration of a semi-structured questionnaire and analysis of blood samples collected from each participant. Absorption spectrophotometry was used to measure serum calcium and albumin concentrations and corrected serum calcium calculated from the Payne's equation. With a statistical significant threshold set at p-value = 0.05, the odds ratio was used as a measure of the strength of association between hypocalcaemia and maternofoetal variables.

RESULTS

We enrolled a total of 354 consenting participants with a mean age of 27.41±5.84 years. The prevalence of hypocalcaemia in late pregnancy was 58.76 [53.42-63.90]%. The rate of calcium supplementation in pregnancy was 57.63[52.28-62.80]% with a mean duration of supplementation of 3.69±1.47 months. When controlled for marital status, age, level of education, and gestational age at delivery, pregnant women with systolic blood pressures below 130 mmHg were significantly less likely to have hypocalcaemia than their counterparts with higher systolic blood pressures (Adjusted Odds Ratio = 0.41[0.18-0.89], p-value = 0.020). No statistically significant associations were found between diastolic blood pressure, body mass index, foetal birth weight and hypocalcaemia.

CONCLUSION

Hypocalcaemia in late pregnancy is highly prevalent (59%) among women accessing reproductive services at the Nkongsamba Regional Hospital. There is also a wide gap in calcium supplementation compared to World Health Organization recommendations. Hypocalcaemia is significantly associated to higher systolic blood pressure in pregnancy. Systematic calcium supplementation and consumption of high calcium containing locally available meals should be encouraged.

Correlation between Breast Arterial Calcification and the 10-year fatal cardiovascular risk by means of the SCORE Risk System

Objectives:

The aim of this study was to investigate the relationship between Breast Arterial Calcification (BAC) on mammography and the 10-year fatal Cardiovascular Disease (CVD) risk by using SCORE risk system.

Methods:

The study was conducted from September 2013 to July 2014. A total of 66 women with BAC and 66 age-matched controls without BAC were analyzed. The groups were compared with respect to demographics, clinical, reproductive, laboratory parameters, and 10-year fatal CVD risk.

Results:

The mean ages of the women in the study was 54.0 years (40-85 years). Hypertension, systolic blood pressure, levels of serum total cholesterol and the calculated SCORE risk were higher in the BAC (+) group than in the BAC (-) group (p=0.04, p=0.031, p=0.046, and p=0.038 respectively). Multivariate analysis showed that none of them was independent factor of BAC on mammograms, only the 10-year fatal CVD risk was close to being statistically significant (OR:1.17, CI:0.98-1.38, p=0.06).

Conclusion:

BAC on mammography was found to be related to the 10-year fatal CVD risk as calculated by the SCORE risk score system. Additional large-scale prospective studies are required to further assess whether BAC can be considered a useful screening tool for CVD risk prediction in women who screened for breast cancer by mammography.

Vitamin D in pregnancy: current perspectives and future directions

As neonatal vitamin D status is determined by circulating maternal 25-hydroxyvitamin D [25(OH)D] concentrations, prevention of maternal vitamin D deficiency during pregnancy is essential for the avoidance of neonatal deficiency. However, a high prevalence of vitamin D deficiency has been extensively reported among gravidae and neonates from ethnic minorities and white populations resident at high latitude. Currently, regulatory authorities recommend vitamin D intakes for pregnant women that are similar to non-pregnant adults of the same age, at 10-15 µg/day (400-600 IU), to meet 25(OH)D thresholds of 25-50 nmol/liter. The lack of pregnancy-specific dietary recommendations is due to inadequate data indicating whether nutritional requirements for vitamin D during pregnancy differ from the non-pregnant state. In addition, there are few dose-response studies to determine the maternal 25(OH)D response to vitamin D intake throughout pregnancy at high latitude. These data are also required to determine vitamin D requirements during pregnancy for prevention of neonatal deficiency, an outcome which is likely to require a higher maternal 25(OH)D concentration than prevention of maternal deficiency only. With regard to the impact of vitamin D on perinatal health outcomes, which could guide pregnancy-specific 25(OH)D thresholds, dietary intervention studies to date have been inconsistent and recent systematic reviews have highlighted issues of low quality and a high risk of bias as drawbacks in the trial evidence to date. Many observational studies have been hampered by a reliance on retrospective data, unclear reporting, suboptimal clinical phenotyping and incomplete subject characterization. Current investigations of vitamin D metabolism during pregnancy have potentially exciting implications for clinical research. This paper provides an update of current dietary recommendations for vitamin D in pregnant women and a synopsis of the evidence relating vitamin D status with maternal and infant health.

The relationship of maternal bone density with nutritional rickets in Nigerian children

Factors that affect maternal bone mineral density may be related to the risk of nutritional rickets in their offspring. Our aim was to determine the relationship between maternal areal bone mineral density (aBMD) and rickets in Nigerian children. Using a case-control design, we measured forearm aBMD in 56 and 135 mothers of children with and without nutritional rickets, respectively. Active rickets was confirmed or excluded in all children radiographically. Using logistic regression, we assessed the association of maternal aBMD, adjusted for parity, pregnancy and lactation status, duration of most recent completed lactation, age of menarche, height, body mass index, and maternal age with nutritional rickets. The median (range) age of all mothers was 30years (17-47years), and parity was 4 (1-12). A total of 36 (19%) were pregnant and 55 (29%) were currently breast feeding. Mean (±SD) metaphyseal forearm aBMDs were 0.321±0.057 and 0.316±0.053g/cm² in mothers of children with and without rickets, respectively (P=0.60). Diaphyseal forearm aBMDs were 0.719±0.071 and 0.715±0.072g/cm², respectively (P=0.69). In an adjusted analysis, maternal forearm aBMD, bone mineral content and bone area at metaphyseal and diaphyseal sites were not associated with rickets in the child. In the adjusted analysis, rickets was associated with shorter duration of most recently completed lactation (aOR 0.91 for each additional month; 95% CI 0.83-0.99), older maternal age (aOR 1.07 for each additional year; 1.00-1.14), and less frequent maternal use of lead-containing eye cosmetics (aOR 0.20; 95% CI 0.05-0.64), without any difference in maternal blood lead levels. Maternal age, parity, age of menarche, height, and body mass index were not associated with having had a child with rickets in multivariate analysis. Nutritional rickets in Nigerian children was not associated with maternal forearm aBMD. Other unidentified maternal characteristics and practices likely contribute to the risk of rickets in Nigerian children.

Determinants of microstructural, dimensional and bone mineral changes postpartum in Swedish women

During lactation, areal (a) and volumetric (v) bone mineral density (BMD) are known to temporarily decrease. Factors that affect skeletal changes postpartum are not fully elucidated. The aim was to study determinants of the previously observed changes in aBMD at lumbar spine, and cortical vBMD, microstructure and dimensions at ultra-distal tibia postpartum. Women (25-40 years) were studied longitudinally at 2 weeks (baseline) and 4 months (n 81), 12 months (n 79) and 18 months (n 58) postpartum. At each visit, blood samples were collected, body weight and height were measured and information about lactation habits, oestrogen contraceptives and physical activity was obtained. Ca intake was measured using 4-d food diaries at 4 months postpartum. Serum 25-hydroxyvitamin D (25OHD) was analysed by liquid chromatography-tandem MS. Skeletal changes were assessed with dual-energy X-ray absorptiometry and high-resolution peripheral quantitative computed tomography. Mean baseline BMI was 24·8 (sd 3·1) kg/m2. Median (quartiles 1-3) duration of total lactation was 8·1 (6·8-10·4) months. Longer duration of full lactation was associated with larger decreases of lumbar spine aBMD and tibia vBMD and microstructure. Higher baseline body weight was associated with smaller decreases in tibia vBMD and microstructure. Higher Ca intake was associated with smaller decreases in tibia cortical vBMD and thickness. Higher baseline 25OHD was only associated with larger decreases in lumbar spine aBMD. In conclusion, lactation and body weight were the main determinants of skeletal changes during the first 18 months postpartum. Ca intake and serum concentrations of 25OHD appear to have different associations with cortical and trabecular bone.

Vitamin D expenditure is not altered in pregnancy and lactation despite changes in vitamin D metabolite concentrations

Pregnancy and lactation are associated with changes in vitamin D and calcium metabolism but the impact of these changes on vitamin D expenditure is unknown. We measured plasma 25(OH)D₃ half-life with a stable-isotope tracer and investigated relationships with vitamin D metabolites in pregnant, lactating and ‘non-pregnant, non-lactating’ (NPNL) women. Vitamin D metabolites, vitamin D binding protein (DBP), PTH and 25(OH)D₃ half-life were measured in third-trimester pregnant women (n22) and repeated during lactation 12 weeks post-partum (n14) and twice in NPNL women (n23 and n10, respectively) in rural Gambia where calcium intakes are low with little seasonality in UVB-exposure. 25(OH)D₃ half-life was not significantly different between groups (mean(SD): 20.6(6.8), 22.6(7.7), 18.0(4.7) and 17.7(9.5) days in pregnant, lactating and NPNL women, respectively). Plasma 25(OH)D₃, 1,25(OH)₂D, and DBP were higher in pregnancy, and calculated free-25(OH)D₃ and PTH were lower (P < 0.05). In lactation, 25(OH)D₃ and 24,25(OH)₂D₃ were lower compared to pregnant (P < 0.001, P = 0.02) and NPNL women (P = 0.04, P = 0.07). Significant associations were observed between half-life and 25(OH)D₃ (+ve) in pregnancy, and in all groups between 25(OH)D₃ and free-25(OH)D₃ (+ve) and PTH and 25(OH)D₃ (−ve) (P < 0.0001). These data suggest that adaptive changes in pregnancy and lactation occur that prevent pronounced changes in vitamin D expenditure.

Association Between Recurrence of Urinary Calculi and Childbirth: A Population-Based Case-Control Study

We examined the recurrence rate of urinary calculi (UC) in women after childbirth. The recurrence of UC is common, but no previous studies mentioned the risk of recurrence after childbirth. We performed a nationwide population-based cohort study to investigate whether childbirth could correlate with the recurrence of UC by using data from the National Health Insurance Research Database in Taiwan. Nulliparous women (age ≥20 years) receiving a diagnosis of first episode of UC between 2000 and 2002 were enrolled. We recorded the events of recurrence between parous patients (n = 737) and matched-control nulliparous patients (n = 737). The average ages for parous patients and controls were 27.41 and 27.54, respectively. The recurrence rate was 11.67% (86 of 737) in the childbirth cohort group and 21.57% (159 of 737) in the nonchildbirth cohort group. The childbirth cohort group was associated with a significantly decreased risk of secondary UC (adjusted hazard ratio, 0.45; 95% confidence interval, 0.35–0.59) compared with those who did not deliver a child. This relationship should be studied further.

Maternal Dietary Supplementation with Oligofructose-Enriched Inulin in Gestating/Lactating Rats Preserves Maternal Bone and Improves Bone Microarchitecture in Their Offspring

Nutrition during pregnancy and lactation could exert a key role not only on maternal bone, but also could influence the skeletal development of the offspring. This study was performed in rats to assess the relationship between maternal dietary intake of prebiotic oligofructose-enriched inulin and its role in bone turnover during gestation and lactation, as well as its effect on offspring peak bone mass/architecture during early adulthood. Rat dams were fed either with standard rodent diet (CC group), calcium-fortified diet (Ca group), or prebiotic oligofructose-enriched inulin supplemented diet (Pre group), during the second half of gestation and lactation. Bone mineral density (BMD) and content (BMC), as well as micro-structure of dams and offspring at different stages were analysed. Dams in the Pre group had significantly higher trabecular thickness (Tb.Th), trabecular bone volume fraction (BV/TV) and smaller specific bone surface (BS/BV) of the tibia in comparison with CC dams. The Pre group offspring during early adulthood had an increase of the lumbar vertebra BMD when compared with offspring of CC and Ca groups. The Pre group offspring also showed significant increase versus CC in cancellous and cortical structural parameters of the lumbar vertebra 4 such as Tb.Th, cortical BMD and decreased BS/BV. The results indicate that oligofructose-enriched inulin supplementation can be considered as a plausible nutritional option for protecting against maternal bone loss during gestation and lactation preventing bone fragility and for optimizing peak bone mass and architecture of the offspring in order to increase bone strength.

Association between prolonged breastfeeding and bone mineral density and osteoporosis in postmenopausal women: KNHANES 2010-2011

This study showed that a negative correlation between duration of breastfeeding and bone mineral density (BMD) in the lumbar spine and prolonged breastfeeding is an independent risk for osteoporosis in postmenopausal women. The present study suggests that postmenopausal women with a history of prolonged breastfeeding require more careful screening for osteoporosis.

INTRODUCTION

Several studies suggest that breastfeeding and childbirth lead to maternal calcium loss and a decline in BMD. While the association between breastfeeding and BMD immediately after weaning is well-established, the effects of breastfeeding on postmenopausal women have been controversial. The aim of this study was to examine the effects of breastfeeding on bone mineral density (BMD) and the prevalence of osteoporosis in postmenopausal women.

METHODS

The present study was a cross-sectional survey based on the Korea National Health and Nutrition Examination Survey (KNHANES) 2010 and 2011 data. The association between breastfeeding and BMD and osteoporosis was examined in 1222 postmenopausal women.

RESULTS

The duration of breastfeeding and BMD in the lumbar spine showed a negative correlation. The association between duration of breastfeeding and BMD remained significant after adjustment for reproductive factors and other confounding factors (P = 0.008). However, the number of deliveries and age at the time of delivery did not correlate with BMD at any site after adjustment. Moreover, the prevalence of osteoporosis in postmenopausal women with a history of prolonged breastfeeding was significantly higher than that in women with a short history of breastfeeding (≥37 months, OR = 3.292; 95 % CI 1.485-7.299). The prevalence of lumbar spine fracture showed a significant increasing trend with the increase in the duration of breastfeeding.

CONCLUSION

Prolonged breastfeeding was significantly associated with low BMD in the lumbar spine and higher prevalence of osteoporosis. However, the number of deliveries or age at the time of childbirth did not influence BMD.

Dietary and pharmacological compounds altering intestinal calcium absorption in humans and animals

The intestine is the only gate for the entry of Ca to the body in humans and mammals. The entrance of Ca occurs via paracellular and intracellular pathways. All steps of the latter pathway are regulated by calcitriol and by other hormones. Dietary and pharmacological compounds also modulate the intestinal Ca absorption process. Among them, dietary Ca and P are known to alter the lipid and protein composition of the brush-border and basolateral membranes and, consequently, Ca transport. Ca intakes are below the requirements recommended by health professionals in most countries, triggering important health problems. Chronic low Ca intake has been related to illness conditions such as osteoporosis, hypertension, renal lithiasis and incidences of human cancer. Carbohydrates, mainly lactose, and prebiotics have been described as positive modulators of intestinal Ca absorption. Apparently, high meat proteins increase intestinal Ca absorption while the effect of dietary lipids remains unclear. Pharmacological compounds such as menadione, dl-butionine-S,R-sulfoximine and ursodeoxycholic acid also modify intestinal Ca absorption as a consequence of altering the redox state of the epithelial cells. The paracellular pathway of intestinal Ca absorption is poorly known and is under present study in some laboratories. Another field that needs to be explored more intensively is the influence of the gene × diet interaction on intestinal Ca absorption. Health professionals should be aware of this knowledge in order to develop nutritional or medical strategies to stimulate the efficiency of intestinal Ca absorption and to prevent diseases.

Use of micronutrient supplements among pregnant women in Alberta: results from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort

Maternal nutrient intake in the prenatal period is an important determinant of fetal growth and development and supports maternal health. Many women, however, fail to meet their prenatal nutrient requirements through diet alone and are therefore advised to consume nutrient supplements. The purpose of this study was to describe the use of natural health products (NHP) by pregnant women in each trimester of pregnancy. Women (n = 599) participating in the first cohort of the Alberta Pregnancy Outcomes and Nutrition (APrON) study completed an interviewer-administered supplement intake questionnaire during each trimester of pregnancy. NHP use was high, with >90% taking multivitamin/mineral supplements, and nearly half taking at least one additional single-nutrient supplement. Compliance with supplementation guidelines was high for folic acid (>90%), vitamin D (∼70%) and calcium (∼80%), but low for iron (<30%) and for all four nutrients together (≤11%). On average, women met or exceeded the recommended dietary allowance for folic acid, vitamin D and iron from NHPs alone, with median daily intakes of 1000 μg, 400 IU and 27 mg, respectively. The median calcium intake was 250 mg d(-1) . Up to 26% of women exceeded the tolerable upper intake level for folic acid and up to 19% did so for iron at some point of their pregnancy. Findings highlight the need to consider both dietary and supplemental sources of micronutrients when assessing the nutrient intakes of pregnant women.

The association of breast arterial calcification and metabolic syndrome

OBJECTIVES

We investigated the relationship between metabolic syndrome and breast arterial calcification detected via mammography in a cohort of postmenopausal subjects.

METHODS

Among 837 patients referred to our radiology department for mammographic screening, 310 postmenopausal females (105 patients with and 205 patients without breast arterial calcification) aged 40 to 73 (mean 55.9 ± 8.4) years were included in this study. The groups were compared with respect to clinical characteristics and metabolic syndrome criteria. Univariate and multivariate analyses identified the factors related to breast arterial calcification.

RESULTS

Age, postmenopausal duration and the frequencies of diabetes mellitus, hypertension and metabolic syndrome were significantly higher in the subjects with breast arterial calcification than in those without (p<0.05). Multivariate analysis indicated that age (OR=1.3, 95% CI=1.1-1.6, p=0.001) and metabolic syndrome (OR=4.0, 95% CI=1.5-10.4, p=0.005) were independent predictors of breast arterial calcification detected via mammography. The independent predictors among the features of metabolic syndrome were low levels of high-density lipoproteins (OR=8.1, 95% CI=1.0-64.0, p=0.047) and high blood pressure (OR=8.7, 95% CI=1.5-49.7, p=0.014).

CONCLUSIONS

The likelihood of mammographic detection of breast arterial calcification increases with age and in the presence of hypertension or metabolic syndrome. For patients undergoing screening mammography who present with breast arterial calcification, the possibility of metabolic syndrome should be considered. These patients should be informed of their cardiovascular risk factors and counseled on appropriate lifestyle changes.

New reference values for calcium

The nutrition societies of Germany, Austria and Switzerland are the joint editors of the 'reference values for nutrient intake'. They have revised the reference values for the intake of calcium and published them in June 2013. The reference values for the calcium intake for infants are derived from the calcium content of breast milk. For infants from 4 to <12 months of age, the calcium intake from solid foods is included in addition to the calcium intake from breast milk. Thus, the reference values for infants are estimated values; they are 220 mg/day for infants to <4 months and 330 mg/day for infants from 4 to <12 months of age. As a parameter for determining the calcium requirement in children and adolescents, calcium retention is taken into account. The average requirement is calculated by the factorial method. A balanced calcium metabolism is calculated based upon calcium balance studies and used as a parameter for the determination of the calcium requirement in adults. On the basis of the average requirement, recommended calcium intake levels for children, adolescents and adults are derived. Depending on age, the recommended calcium intake ranges between 600 mg/day for children aged 1 to <4 years and 1,200 mg/day for adolescents aged 13 to <19 years; for adults, it is 1,000 mg/day.

Calcium intake in health maintenance - a systematic review

Background

Calcium (Ca) is an essential nutrient for the human body. Despite lively research, there is uncertainty about Ca requirements in terms of desirable health outcomes including an upper intake level above which the potential for harm increases.

Objectives

The aim was to conduct a review to update requirements and desirable or harmful health effects of Ca on the current scientific evidence.

Methods

We searched Medline and Swemed from January 2000 to December 2011 and included all systematic reviews that reported Ca supplementation or usual Ca intake on health outcomes. Meta-analyses, randomized clinical trials and cohort studies were included in the second search between May 2009 and March 2011 and an additional search covering studies till the end of 2011. This review concentrated on studies reporting independent effects of Ca, although a few recent trials report sole effects of Ca on health outcomes, most trials use Ca in combination with vitamin D vs. placebo.

Results

In total, we reviewed 38 studies addressing the effects of Ca on bone, pregnancy-related outcomes, cancers, cardiovascular outcomes, obesity, and mortality. There was a lot of heterogeneity in the study protocols, which made it difficult to draw any strong conclusions. According to the literature, high Ca intake seems to have a small positive effect on bone mineral content (BMC) or bone mineral density (BMD) in children and postmenopausal women. We did not find any consistent evidence on the effects of Ca on bone health in premenopausal women or men. Also, the evidence that Ca supplementation reduces fracture incidence is scarce and inconsistent. Maternal diet may influence the peak bone mass of offspring but more studies are required. There was no overall effect of Ca intake on cancers. Ca was associated with a decreased risk of breast cancer and a slightly increased risk of prostate cancer in two of the three studies. No associations were found with other cancers. We found no consistent association between cardiovascular outcomes and Ca intake except for blood pressure. A small decrease of 2–4 mmHg in systolic blood pressure was found in pregnant and in hypertensive subjects with Ca supplementation. Reviewed studies did not show consistent evidence relating Ca intake to either mortality or obesity.

Conclusion

Based on this evidence, there is no need to change the Nordic recommendations for Ca intake. However, due to heterogeneity in the studies it is difficult to interpret the results and provide single summary statement.

Breast Arterial Calcification: a New Marker of Cardiovascular Risk?

Mammographically-detected breast arterial calcifications (BAC) are considered to be an incidental finding without clinical importance since they are not associated with increased risk of breast cancer. The goal of this article is to review existing evidence that the presence of BAC on mammography correlates with several (but not all) traditional cardiovascular disease (CVD) risk factors and with prevalent and incident CVD. Thus, BAC detected during routine mammography is a noteworthy finding that could be valuable in identifying asymptomatic women at increased future CVD risk that may be candidates for more aggressive management. In addition, there are notable differences in measures of subclinical atherosclerosis burden in women (ie, coronary artery calcification) by race/ethnic background, and the same appears to be true for BAC, although data are very limited. Another noteworthy limitation of prior research on BAC is the reliance on absence vs presence of BAC; no study to date has determined gradation of BAC. Further research is thus required to elucidate the role of BAC gradation in the prediction of CVD outcomes and to determine whether adding BAC gradation to prediction models based on traditional risk factors improves classification of CVD risk.

Daughter dearest: Sex-biased calcium in mother's milk among rhesus macaques

Mother's milk provides building blocks necessary for infant development and growth postnatally. Minerals in milk are particularly important for infant skeletal development and may reflect maternal characteristics that are associated with the capacity to synthesize milk and sex-specific developmental priorities of the infant. Using a large sample of mother-infant dyads assigned to the outdoor breeding colony at the California National Primate Research Center (N=104), we investigated the relationship of milk calcium (Ca) and phosphorus (P) concentrations and the ratio of Ca/P to maternal and infant characteristics and to other milk variables. Ca and P are largely associated with casein micelles, and as expected, both Ca and P were positively correlated with protein concentrations in milk. Neither Ca nor P concentrations were associated with maternal parity. Mothers rearing daughters tended to produce higher mean Ca concentration in milk, and consequently a higher Ca/P ratio, than did mothers rearing sons, even though protein concentration was not elevated. These results suggest that the Ca/P ratio in rhesus milk may have been under separate selective pressure from protein content to facilitate the accelerated rate of skeletal calcification that has been observed in female Macaca mulatta infants.

Relationship between maternal sodium intake and blood lead concentration during pregnancy

Pb is released from bone stores during pregnancy, which constitutes a period of increased bone resorption. A high Na intake has been found to be negatively associated with Ca and adversely associated with bone metabolism. It is possible that a high Na intake during pregnancy increases the blood Pb concentration; however, no previous study has reported on the relationship between Na intake and blood Pb concentration. We thus have investigated this relationship between Na intake and blood Pb concentrations, and examined whether this relationship differs with Ca intake in pregnant Korean women. Blood Pb concentrations were analysed in 1090 pregnant women at mid-pregnancy. Dietary intakes during mid-pregnancy were estimated by a 24 h recall method covering the use of dietary supplements. Blood Pb concentrations in whole-blood samples were analysed using graphite furnace atomic absorption spectrophotometry. Multiple regression analysis performed after adjustment for covariates revealed that maternal Na intake was positively associated with blood Pb concentration during pregnancy, but only when Ca intake was below the estimated average requirement for pregnant Korean women (P= 0·001). The findings of the present study suggest that blood Pb concentration during pregnancy could be minimised by dietary recommendations that include decreased Na and increased Ca intakes.

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.

Differences in bone metabolism between singleton pregnancy and twin pregnancy

OBJECTIVE

The objective of this study was to examine the influence of twin pregnancy on calcium metabolism, including bone turnover markers and calcium-regulating factors, by comparison between singleton pregnancy and twin pregnancy in women during pregnancy and puerperium in cross-sectional and longitudinal studies.

METHODS

Women with singleton and twin pregnancies were recruited from the outpatient clinic of Tokushima University Hospital. In both cross-sectional and longitudinal studies, bone formation and resorption markers, mineral metabolism and calcium-regulating factors were measured at 10, 25, 30 and 36 weeks of pregnancy and at 4 days and 1 month postpartum in women with singleton and twin pregnancies.

RESULTS

Urinary levels of cross-linked type I collagen N-telopeptides and C-terminal telopeptides of type I collagen in women with twin pregnancy were significantly higher than those in women with singleton pregnancy and those high levels were observed earlier than those in women with singleton pregnancy. In the cross-sectional study, serum levels of bone-specific alkaline phosphatase, calcium and phosphate in women with twin pregnancy were higher and the levels of 1,25-(OH)2 vitamin D and 25-(OH) vitamin D in women with twin pregnancy were lower than those in women with singleton pregnancy.

CONCLUSION

Changes in bone metabolism in women with twin pregnancy are different from those in women with singleton pregnancy. Early and large increases in bone turnover markers allow women with twin pregnancy to meet high fetal demand for calcium during pregnancy.

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/m(2); 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.

Lactation and bone turnover: a conundrum of marked bone loss in the setting of coupled bone turnover

CONTEXT

Mothers who exclusively breastfeed lose up to 10% of their bone mass. This is primarily mediated by PTHrP, in combination with low estrogen levels. The mechanisms underlying this marked bone loss are unknown. Uncoupling of bone turnover, which is seen in other prototypical states of bone loss, would seem the likely explanation. However, the most current markers of bone turnover have not been studied in human lactation.

OBJECTIVES

The purpose of this study was to assess bone formation in lactating humans using the most current bone turnover markers.

DESIGN AND PARTICIPANTS

We conducted a prospective cohort study with repeated measures of bone metabolism in a volunteer sample of 49 women, recruited into three study groups: lactating, bottle feeding, and healthy controls. The postpartum women were studied at 6-8 and 12-14 wk postpartum, whereas the controls were studied at the follicular phase of their menstrual cycles.

OUTCOME MEASURES

Biochemical markers of bone turnover were assessed.

RESULTS

Mean serum C-telopeptide of type I collagen, a sensitive marker of bone resorption, was approximately 2-fold higher in lactating women as compared with bottle-feeding and healthy controls (P = 0.037 and P < 0.001, respectively). Surprisingly, amino-terminal telopeptides of procollagen 1, the most current marker of bone formation, bone-specific alkaline phosphatase, and osteocalcin were all significantly higher in the lactating group as compared with controls (P < 0.001, P = 0.002, and P < 0.001, respectively).

CONCLUSIONS

In contrast to prototypical states of rapid bone loss (myeloma, cancer, and immobilization) in which markers of bone turnover display marked uncoupling, lactational bone loss, as assessed in this small exploratory study, is distinct, showing comparably rapid bone loss in the face of apparent osteoclast-osteoblast coupling.

The influence of late pregnancy and lactation on bone metabolism in mares

Pregnancy and lactation are periods of significant influence on bone metabolism that has not been investigated in equines. To examine the influence of late pregnancy and lactation on bone metabolism in mares, the changes in the blood serum/plasma total calcium (Ca), inorganic phosphates (Pi), pyridinoline (Pyd) and 17beta-estradiol (E2) concentration and the bone alkaline phosphatase (BAP) activity were investigated. The samples were taken from 11 mares on 60+/-10 and 20+/-10 days before foaling, and 20+/-10 and 60+/-10 days after foaling. The concentration/activity of Ca, Pi, Pyd and BAP increased significantly in early lactation, but the Pyd than decreased in the 4th period. A significant correlation was observed between the E2 and bone metabolism parameters. The results indicate low maintenance of normocalcaemia with reduced bone synthesis in late pregnancy and prove the role of estradiol in bone metabolism in mares during pregnancy and lactation.

Calcium and bone health: position statement for the Australian and New Zealand Bone and Mineral Society, Osteoporosis Australia and the Endocrine Society of Australia

This position statement was prepared by the Working Group of the Australian and New Zealand Bone and Mineral Society and Osteoporosis Australia. The final statement was endorsed by the Endocrine Society of Australia. Currently, the balance of evidence remains in favour of fracture prevention from combined calcium and vitamin D supplementation in elderly men and women. Adequate vitamin D status is essential for active calcium absorption in the gut and for bone development and remodelling. In adults with a baseline calcium intake of 500-900 mg/day, increasing or supplementing this intake by a further 500-1000 mg/day has a beneficial effect on bone mineral density. Calcium intake significantly above the recommended level is unlikely to achieve additional benefit for bone health.

Nutrition during pregnancy

Nutritional concerns in pregnancy are gaining increasing importance as problems with obesity, poor nutrition, and improper weight gain during pregnancy have been shown to result in morbidity for mother and infant during the pregnancy. More recent studies show that the impact of poor nutrition in pregnancy extends for decades to follow for the mother and the offspring. Clearly, prevention of problems is the best approach. This article discusses aspects of, and controversies concerning, prenatal weight gain and specific nutrients, and special patient groups who may benefit from intervention by a registered dietitian.

Vitamin D: a growing perspective

Vitamin D deficiency has been widely reported in all age groups in recent years. Rickets has never been eradicated in developed countries, and it most commonly affects children from recent immigrant groups. There is much evidence that current vitamin D guidelines for the neonatal period, 5-10 microg (200-400 IU)/day, prevent rickets at the typical calcium intakes in developed countries. The annual incidence of vitamin D-deficiency rickets in developed countries ranges between 2.9 and 7.5 cases per 100,000 children. The prevalence of vitamin D deficiency in mothers and their neonates is remarkable, and the results of one study suggest that third-trimester 25-hydroxyvitamin D (25(OH)D) is associated with fetal bone mineral accrual that may affect prepubertal bone mass accumulation. Beyond infancy, the evidence indicates that 5 microg (200 IU)/day of vitamin D has little effect on vitamin D status as measured by the serum 25(OH)D concentration. Two randomized clinical trials show that higher vitamin D intake improves one-year gain in bone density in adolescent girls. The functions of vitamin D extend beyond bone to include immune system regulation and anti-proliferative effects on cells. Early life vitamin D inadequacy is implicated in the risk of bone disease, autoimmune disease, and certain cancers later in life; however, long-term interventional studies do not exist to validate the widespread implementation of greater vitamin D consumption. Here we review the available data concerning vitamin D status and health effects of vitamin D in pregnancy through to and including adolescence.

The association of pregnancy history with areal and volumetric bone mineral density in adolescence

INTRODUCTION

Studies demonstrate that pregnancy may interfere with bone mineral density. Adolescence is a crucial time of life for bone mass acquisition and there are some questions as to the influence of pregnancy on bone mass at this age.

OBJECTIVE

To evaluate the association between pregnancy history and areal (BMD) and volumetric (vBMD) bone mineral density in adolescence.

SUBJECTS AND METHODS

A cross-sectional study of 119 adolescents ranging from 12-20 years of age was conducted; 30 of these girls had a history of full-term pregnancy. The adolescents were selected during a routine visit to the Adolescent Gynecology Outpatient Facility, completed a questionnaire, and had a physical examination to evaluate weight, height and Tanner stage. Bone mineral densitometry of the lumbar spine (L(1)-L(4)) and total body (TB) was performed to measure bone mineral density and body composition.

RESULTS

The mean measurements of the area, bone mineral content (BMC), BMD and vBMD of L(1)-L(4) and the area, BMC and BMD of TB were not significantly different between adolescents with and without a pregnancy history, stratified by chronologic and gynecologic age. The percentage of adolescents with altered Z-scores was similar in both groups, and the prevalence ratio showed no association between pregnancy history and low bone mass (PR=0.52; CI 0.04-6.07). Upon multiple regression analysis, body mass index (BMI) and lean body mass (LBM) were the main factors associated with lumbar spine and total body measurements. Pregnancy history was inversely associated with areal BMD of L(1)-L(4) (R (2)=0.04) and vBMD of L(1)-L(4) (R (2)=0.04), accounting for only 4% variation in the lumbar spine.

CONCLUSION

These data suggest that adolescent pregnancy seems to exert no significant influence on the acquisition of bone mass and does not appear to represent a risk factor for osteoporosis in the future.

Biodisponibilidade do cálcio dietético

O cálcio (Ca) dietético é fundamental para a saúde óssea. Tanto o teor como a biodisponibilidade do elemento nos alimentos devem ser considerados. Este artigo objetiva sumarizar os fatores envolvidos na absorção e destacar os alimentos com melhor disponibilidade do Ca. Este é absorvido principalmente no jejuno e o pH baixo parece favorecer sua absorção, que é maior no crescimento, na gestação/lactação e na carência de Ca ou fósforo (P), e menor no envelhecimento. As maiores fontes, e com melhor absorção, são os laticínios bovinos. Outros alimentos apresentam concentrações elevadas de Ca, mas com biodisponibilidade variável: os ricos em ácidos oxálico e fítico apresentariam uma menor absorção, enquanto que os ricos em carboidratos teriam uma absorção maior. Por apresentarem uma biodisponibilidade do Ca mais próxima da do leite bovino, o leite de outros animais, o de soja enriquecido e alguns vegetais, em quantidades adequadas, poderiam ser usados como alternativas a este.

Effects of Dietary Calcium Intervention on Adolescent Mothers and Newborns

OBJECTIVE

To evaluate the effects of dietary calcium (Ca) intervention on adolescent pregnant mothers and their newborns.

METHODS

Seventy-two pregnant adolescent mothers were randomized into one of 3 groups: control, orange juice fortified with calcium, and dairy. The orange juice and dairy groups were required to take more than 1,200 mg Ca. Calcium tablets were added for those not able to meet required Ca. Maternal and infant weight, length, and blood pressure (BP) were recorded. Maternal dietary records were evaluated. Mother's blood was drawn for serum Ca, phosphate (P), magnesium (Mg), and vitamin 25-hydroxyvitamin D (D). Cord blood was collected for serum Ca and D. Newborn total body Ca was determined.

RESULTS

All mothers were similar in weight, height, and BP. Mothers in the orange juice plus calcium and dairy groups had higher intakes of Ca (1,472 mg and 1,771 mg) than controls (862 mg). One half of the mothers in the orange juice plus calcium group required Ca tablets. Mothers in the dairy group had higher intakes of P, D, and Mg, higher serum folate and D, and higher cord D levels. Mothers in the orange juice plus calcium group had higher serum P but lower serum folate and D. Infants (3,517+/-273 g) in the dairy group were heavier than infants in the control (3,277+/-177 g) and orange juice plus calcium (3,292+/-165 g) groups. Infants in the dairy group had higher total body calcium than control infants.

CONCLUSION

Calcium diet supplemented with dairy products during adolescent pregnancy resulted in higher maternal vitamin D and folate serum levels and higher newborn weight and bone mineralization compared with controls.

Arterial calcifications seen on mammograms: cardiovascular risk factors, pregnancy, and lactation

PURPOSE

To retrospectively assess if mammographic calcium deposits are related to coronary heart disease (CHD) risk factors and reproductive factors in a subset of women participating in the European Prospective Investigation into Cancer and Nutrition study.

MATERIALS AND METHODS

The study was approved by the institutional review board of the University Medical Center Utrecht; informed consent was obtained. Mammograms were evaluated by two radiologists for the presence of breast arterial calcifications (BAC) in the Prospect cohort, a breast cancer screening population of women aged 49-70 years (mean, 57 years) within the European Prospective Investigation into Cancer and Nutrition study. Cardiovascular risk factors and reproductive factors were examined for independent effects on the prevalence of BAC. Logistic regression analysis was performed.

RESULTS

BAC was present in 194 of 1699 (11%) women and increased with age to 20% in the highest quartile of age (mean, 66 years). The odds ratio was 4.7 in the highest versus the lowest quartile of age (95% confidence interval [CI], 2.9, 7.6). After adjustment for age, no significant association was found between BAC and traditional cardiovascular risk factors. Current smoking was inversely related to BAC (odds ratio, 0.6; 95% CI: 0.4, 0.9). BAC was prevalent in 2.5% of nulliparous women, in 9% of women with one or two children, and in 17% of women with three or more children (odds ratio, 7.2; 95% CI: 2.9, 18.0). Breast feeding after pregnancy was significantly associated with BAC in women who ever were pregnant (odds ratio, 2.2; 95% CI: 1.4, 3.6).

CONCLUSION

Calcifications in arteries on mammograms are associated with increasing age, pregnancy, and lactation but not with various cardiovascular risk factors.

Calcium supplementation during pregnancy and lactation: effects on the mother and the fetus

Calcium consumption is essential for bone development and maintenance throughout life, yet more than one half of the female population in the United States does not consume the recommended amount of calcium. Calcium intake is especially crucial during pregnancy and lactation because of the potential adverse effect on maternal bone health if maternal calcium stores are depleted. There is often a transient lowered bone mineral density and increased rate of bone resorption, with the greatest consequence during the third trimester and throughout lactation. Studies indicate that calcium consumption should be encouraged, especially during pregnancy and lactation, to replace maternal skeletal calcium stores that are depleted during these periods. Because the fetus in utero and the neonate through breast-feeding are dependent on maternal sources for the total calcium load, adequate maternal calcium intake also can affect fetal bone health positively. Proper calcium consumption can be attained through the diet by the consumption of dairy products or leafy greens (such as kale), the consumption of fortified foods, or by supplementation with widely available calcium-containing supplement products. Because many women experience heartburn during pregnancy, calcium-based antacids are ideal for providing heartburn relief, and they offer a calcium supplement to ensure maternal and fetal bone health, without the danger of adverse effects on the neonate.

Isotopic evidence for breastfeeding and possible adult dietary differences from Late/Sub-Roman Britain

Historical documents indicate that breastfeeding and weaning practices have fluctuated in England through history. In order to obtain evidence for general breastfeeding patterns in Late/Sub-Roman Britain, stable carbon and nitrogen isotope values were measured in juvenile and adult skeletons (n = 87) from the cemetery of Queenford Farm, Dorchester-on-Thames, Oxfordshire. As the site contained few individuals between 0-1.5 years of age, it was not possible to determine the initial timing for the introduction of weaning foods. Between ages 2-4 years, the mean +/- SD delta(13)C results (-20.2 +/- 0.3 per thousand) are significantly more negative (t = -4.03, P < 0.001) compared to adult females (-19.7 +/- 0.3 per thousand). This is interpreted as evidence of a different diet being fed to children during weaning. After age 2, the delta(15)N values gradually decline, indicating complete cessation of breastfeeding by 3-4 years. Among adults, stature (males = 1.68 +/- 0.06 m; females = 1.58 +/- 0.07 m) and sexual dimorphism (106) were low, suggesting that the population was possibly under environmental stress. The delta(13)C results for adults are similar, but females show a small but statistically significantly (t = -2.86, P < 0.01) lower mean delta(15)N value (9.9 +/- 0.9 per thousand) compared to males (10.6 +/- 0.5 per thousand). These lower female delta(15)N values possibly reflect the different physiology of the sexes (pregnancy and/or lactation) or the reduced consumption of animal/fish protein by women, and this may have been influenced by individual preference, family needs, or societal values of the era.

Influence of maternal bone lead burden and calcium intake on levels of lead in breast milk over the course of lactation

The authors studied 367 women who were breastfeeding their infants in Mexico City, Mexico, between 1994 and 1995 to evaluate the effect of cumulative lead exposure, breastfeeding practices, and calcium intake on breast milk lead levels over the course of lactation. Maternal blood and breast milk lead levels were measured at 1, 4, and 7 months postpartum. Bone lead measurements were obtained at 1 month postpartum. At 1, 4, and 7 months postpartum, respectively, the mean breast milk lead levels were 1.4 (standard deviation (SD), 1.1), 1.2 (SD, 1.0), and 0.9 (SD, 0.8) microg/liter and showed a significant decreasing trend over the course of lactation (p < 0.00001). The relations of bone lead and blood lead to breast milk lead were modified by breastfeeding practice, with the highest breast milk lead levels among women with a high level of patella lead who were exclusively breastfeeding. Dietary calcium supplementation increased the rate of decline in breast milk lead by 5-10%, in comparison with a placebo, over the course of lactation, suggesting that calcium supplementation may constitute an important intervention strategy, albeit with a modest effect, for reducing lead in breast milk and thus the potential for exposure by infants.

A comparison of the dietary and total intake of micronutrients in a group of pregnant Greek women with the Dietary Reference Intakes

OBJECTIVE

We compared the dietary and total (diet and supplement) intake of micronutrients with the Dietary Reference Intakes (DRIs) from the USA in a population of pregnant Greek women.

METHODS

Two hundred pregnant women participated in a nutritional survey, 98 in the second trimester and 102 in the third trimester in a random sampling. To examine dietary intake we used two questionnaires, the nutritional questionnaire for pregnant women from the California Department of Health Services, and a semi-quantitative questionnaire (Walter Willet) with modifications for use in Greece. Dietary intake analysis was performed using the Diet Analysis Plus software, Version 3, ESHA Research. Statistical analysis was performed with Minitab for Windows, Release 12. A simple complementary questionnaire concerning demographic and socio-economic features was also completed.

RESULTS

The average total intake of vitamins A, B(1), B(2), B(3), B(6), B(12) and C, calcium and phosphorus was higher than the respective DRIs. Folic acid and iron intake exceed the highest values specified for pregnancy. Vitamin E and zinc was lower than the DRIs, while vitamin D, magnesium and thiamin did not differ.

CONCLUSIONS

The results of our study suggest that in a Greek population, sufficient micronutrients appear to be received in adequate amount from diet, except for folic acid and iron, which also had to be taken in the form of nutritional supplements.

Maternity and bone mineral density

During pregnancy and lactation, changes occur in a variety of factors which have great potential to influence bone mineral density (BMD). Smoking habits, the level of alcohol consumption, the level of physical activity, body weight, soft tissue composition and hormone levels are all factors that change during the course of these conditions. Some of these factors are capable of increasing BMD, and some can reduce it. Due to these various changes, it is virtually impossible to predict the development in BMD that will occur during a pregnancy and lactation. However, longitudinal studies have suggested that both pregnancy and lactation are associated with a BMD loss of up to 5%, albeit that the BMD recovers after weaning. Cross-sectional studies have indicated that women with many children and a long total period of lactation have similar or higher BMD and similar or lower fracture risk than their peers who have not given birth. As the studies showing this trend have been observational and cross sectional case-control studies, the conclusions can only be regarded as being suggestive, and no causality can be proven.

Effects of pregnancy and lactation on the microhardness of rat incisor dentine and enamel

Pregnancy and lactation affect the rate of maternal dentine apposition and mineralization in the rat. In this study we have measured the effects of pregnancy and lactation on the degree of mineralization of dentine and enamel by using the microhardness method in rat incisors. At incisal sections, pregnant and lactation group enamel values were increased compared to that of a control group; the pregnancy and post-lactation period dentine values decreased slightly compared to the control group. At neck sections, pregnant and lactation group enamel values were decreased compared to that of the control group; the pregnancy and post-lactation period dentine values were also decreased slightly compared to the control group. At the post-lactation period neck section dentine mineralization was decreased compared with the incisal section. As a result, enamel and dentine layers of rat incisors are affected to varying degrees by these changes in mineralization levels during the maternal period.

Lifestyle influences on 9-year changes in BMD in young women

The effects of dietary calcium intake and physical activity on longitudinal changes in BMD over a mean of 9.4 years were examined in 62 healthy young women. Proximal femur BMD declined, lumbar spine BMD increased, and physical activity was associated with BMD change at intertrochanter and total hip sites.

INTRODUCTION

Maximizing premenopausal BMD is an important strategy for the prevention of osteoporosis and resultant fractures later in life.

MATERIALS AND METHODS

Young women who previously participated in a placebo-controlled 2-year calcium intervention study at a mean age of 18.5 +/- 0.3 years were remeasured at 27.8 +/- 1.0 years of age. DXA (Hologic QDR 1000W) was used to measure changes in BMD, and lifestyle factors were ascertained by questionnaire.

RESULTS AND CONCLUSIONS

Early decline in BMD at the neck of femur (-3.3%/decade) and the converse gain in BMD at the lumbar spine (+4.3%/decade) and intertrochanter (+1.9%/decade) suggest site-specific changes in BMD in young premenopausal women. No effect of previous calcium supplementation was seen on current BMD or changes in BMD (p > 0.10). Lifestyle predictors of change in BMD were determined using hierarchical regression analysis after forced correction for the covariates baseline BMD and previous calcium supplementation. Physical activity was positively associated with change in BMD at total hip and intertrochanter sites (beta-coefficients, beta = 0.26 and 0.26 respectively; p < 0.05). Calcium intake was negatively associated with change in BMD at the lumbar spine (beta = -0.27, p < 0.05). Parity was negatively associated with change in BMD at all sites (beta = -0.40 to -0.26, p < 0.05). These data show that BMD is already declining at the proximal femur in these healthy young women. Physical activity assists in maintenance of BMD at some sites and thus may contribute to lifelong fracture prevention. There was no positive association between calcium intake and change in BMD.

Nitrogen balance and delta15N: why you're not what you eat during pregnancy

Carbon (13C/12C) and nitrogen (15N/14N) stable isotope ratios were longitudinally measured in human hair that reflected the period from pre-conception to delivery in 10 pregnant women. There was no significant change in the delta13C results, but all subjects showed a decrease in delta15N values (-0.3 to -1.1 per thousand) during gestation. The mechanisms causing this decrease in hair delta15N have not been fully elucidated. However, since the delta15N values of dietary nitrogen and urea nitrogen are significantly lower compared to maternal tissues, it is hypothesized that the increased utilization of dietary and urea nitrogen for tissue synthesis during pregnancy resulted in a reduction of the steady state diet to a body trophic level effect by approximately 0.5-1 per thousand. An inverse correlation (R2 = 0.67) between hair delta15N and weight gain was also found, suggesting that positive nitrogen balance results in a reduction of delta15N values independent of diet. These results indicate that delta15N measurements have the ability to monitor not only dietary inputs, but also the nitrogen balance of an organism. A potential application of this technique is the detection of fertility patterns in modern and ancient species that have tissues that linearly record stable isotope ratios through time.

Composition of gestational weight gain impacts maternal fat retention and infant birth weight

OBJECTIVE

The purpose of this study was to evaluate how changes in gestational weight and body composition affect infant birth weight and maternal fat retention after delivery in underweight, normal-weight and overweight women.

STUDY DESIGN

We assessed the body composition of 63 women (low body mass index, 17 women; normal body mass index, 34 women; and high body mass index, 12 women) on the basis of measurements of total body nitrogen by prompt-gamma activation analysis, total body potassium by whole body counting, and a multicomponent model based on total body water by deuterium dilution, body volume by densitometry, and bone mineral content by dual energy x-ray absorptiometry (DXA) before pregnancy, at 9, 22, and 36 weeks of gestation, and at 2, 6, and 27 weeks after delivery. Infant weight and length were recorded at birth; infant anthropometry and body composition by DXA were assessed at 2 and 27 weeks of age.

RESULTS

Gestational weight gain was correlated significantly with gains in total body water, total body potassium, protein, fat-free mass, and fat mass (P=.001-.003). Gains in total body water, total body potassium, protein and fat-free mass did not differ among body mass index groups; however, fat mass gain was higher in the high body mass index group (P=.03). Birth weight was correlated positively with gain in total body water, total body potassium, and fat-free mass (P<.01), but not fat mass. Postpartum weight and fat retention were correlated positively with gestational weight gain (P=.001) and fat mass gain (P=.001) but not with total body water, total body potassium, or fat-free mass gain.

CONCLUSION

Appropriate, but not excessive, gestational weight gain is needed to optimize infant birth weight and minimize maternal postpartum fat retention.

Interrelationship between bone turnover markers and dietary calcium intake in pregnant women: a longitudinal study

This longitudinal study evaluated bone turnover and the interrelationship between changes in bone biomarkers and habitual dietary calcium intake during pregnancy in a group of women ranging widely with regard to dietary calcium intake. Thirty-nine healthy pregnant and 30 nonpregnant women were studied. Calcium, phosphorus, 1alpha,25-dihydroxyvitamin D (1,25diHOD), bone alkaline phosphatase (bALP), carboxyterminal propeptides of type I procollagen (PICP) and carboxyterminal telopeptides of type I collagen (betaCTX and ICTP) were measured in serum and calcium, and creatinine and aminoterminal telopeptide (NTX) were determined in urine. Serum calcium and phosphorus did not change but the urinary Ca/Creat ratio and 1,25diHOD increased throughout pregnancy (P < 0.001 and P < 0.0001, respectively). Serum b-ALP and PICP increased during the last two trimesters (P < 0.0001 and P < 0.001, respectively). All studied bone resorption markers increased compared to nonpregnant values throughout pregnancy. The highest increment was observed in the third trimester. The level of significance decreased as follows: betaCTX > NTX >ICTP. Serum 1,25 diHOD versus calcium intake showed a positive and significant correlation (r = 0.51, P < 0.02). A negative correlation between the absolute change in betaCTX, NTX, and b-ALP between the third and second trimester and calcium intake at the end of pregnancy was observed in pregnant women who did not cover adequately calcium intake requirements (r = -0.47, P < 0.03; r = -0.41, P < 0.05; and r = -0.43, P < 0.05, respectively). These results suggest that skeletal response to pregnancy may not be entirely independent of maternal calcium intake, especially in women with usually low calcium intake. In summary, not only hormonal changes in calcium metabolism that occur during pregnancy but also other considerations, such as low dietary calcium intake, may lead to an increment in the biological activity of the skeleton. Additional studies must be conducted to confirm our findings and to gain a better understanding of skeletal response to a low calcium intake during pregnancy.