Biomedical subjects

M B Andon

Publications and source records attributed to M B Andon.

At least 19 recordsLinked to original sources

PubMed1998

Iron status, menarche, and calcium supplementation in adolescent girls.

The effects of growth, menstrual status, and calcium supplementation on iron status were studied over 4 y in 354 girls in pubertal stage 2 who were premenarcheal at baseline (x+/-SD age: 10.8+/-0.8 y). Girls were randomly assigned to placebo or treatment with 1000 mg Ca/d as calcium citrate malate. Anthropometric characteristics, bone mass, and nutritional status were measured biannually; ferritin was measured annually; and red blood cell indexes were determined at 4 y. The simultaneous effects of iron intake and menstrual status on serum ferritin, after change in lean body mass (LBM) was controlled for, were evaluated in subjects in the upper and lower quartiles of cumulative iron intake. The average maximal accumulation of LBM (386 g/mo; 95% CI: 372, 399) occurred 0.5 y before the onset of menarche. Change in LBM was a significant predictor of serum ferritin (P < 0.0001), with a negative influence on iron status (t ratio=-4.12). The 2 fitted mathematical models representing ferritin concentrations of subjects in the upper and lower quartiles of cumulative iron intake were significantly different (P < 0.018). The regression line of the ferritin concentration in menstruating girls with high iron intakes had a less negative slope than the line fit to serum ferritin concentrations in girls with low iron intakes (NS). Serum ferritin concentrations at 0, 1, 2, 3, and 4 y were not significantly different between groups. In addition, there was no significant difference between groups in any of the red blood cell indexes. In summary, growth spurt and menstrual status had adverse effects on iron stores in adolescent girls with low iron intakes (<9 mg/d), whereas long-term supplementation with calcium (total intake: approximately 1500 mg/d) did not affect iron status.

Adolescent↗

PubMed1997

Zinc balance in adolescent females consuming a low- or high-calcium diet.

There is increasing evidence that calcium intake up to the threshold amount (1480 mg/d) increases bone mass during growth. However, there is concern that such a high calcium intake may interfere with the utilization of other nutrients such as zinc, which is also important for skeletal development. The purpose of our study was to investigate the effect of long-term calcium supplementation on zinc utilization in 26 adolescent females (mean +/- SD age 11.3 +/- 0.5 y) during a 14-d period. Each day subjects consumed a metabolic diet containing 722 mg Ca and 6.3 mg Zn. Participants were randomly assigned to receive either a placebo or a calcium supplement containing 1000 mg supplemental Ca/d as calcium citrate malate. Supplementation began 15 wk before the balance period to allow for adaptation to the greater calcium intake. Mean (+/-SD) zinc balance (0.8 +/- 0.8 compared with 0.3 +/- 1.1 mg/d, P = 0.23), fecal zinc (4.3 +/- 0.6 compared with 4.7 +/- 1.4 mg/d, P = 0.27), urinary zinc (0.4 +/- 0.2 compared with 0.5 +/- 0.1 mg/d, P = 0.55), and net zinc absorption (21% compared with 15%, P = 0.33) were not significantly different between the high- and low-calcium groups. Our results suggest that increasing the recommended dietary allowance of calcium to 1500 mg/d as recommended by the National Institutes of Health consensus panel will not have adverse effects on zinc utilization in adolescent females.

Absorption↗

PubMed1996

The effect of calcium supplementation and Tanner stage on bone density, content and area in teenage women.

One hundred and twelve Caucasian girls, 11.9 +/- 0.5 years of age at entry, were randomized into a 24-month, double-masked, placebo-controlled trial to determine the effect of calcium supplementation on bone mineral content, bone area and bone density. Supplementation was 500 mg calcium as calcium citrate malate (CCM) per day. Controls received placebo pills, and compliance of both groups averaged 72%. Bone mineral content, bone mineral area and bone mineral density of the lumbar spine and total body were measured by dual energy X-ray absorptiometry (DXA). Calcium intake from dietary sources averaged 983 mg/day for the entire study group. The supplemented group received, on average, an additional 360 mg calcium/day from CCM. At baseline and after 24 months, the two groups did not differ with respect to anthropometric measurements, urinary reproductive hormone levels or any measurement of pubertal progression. The supplemented group had greater increases of total body bone measures: content 39.9% versus 35.7% (p = 0.01), area 24.2% versus 22.5% (p = 0.15) and density 12.2% versus 10.1% (p = 0.005). Region-of-interest analyses showed that the supplemented group had greater gains compared with the control group for bone mineral density, content and area. In particular, in the lumbar spine and pelvis, the gains made by the supplemented group were 12%-24% greater than the increases made by the control group. Bone acquisition rates in the two study groups were further compared by subdividing the groups into those with below- or above-median values for Tanner score and dietary calcium intake. In subjects with below-median Tanner scores, bone acquisition was not affected by calcium supplementation or dietary calcium level. However, the calcium supplemented subjects with above-median Tanner had higher bone acquisition rates than the placebo group with above-median Tanner scores. Relative to the placebo group, the supplemented group had increased yearly gains of bone content, area and density which represented about 1.5% of adult female values. Such increases, if held to adult skeletal maturity, could provide protection against future risk of osteoporotic fractures.

Absorptiometry, Photon↗

PubMed1996

Calcium absorption from apple and orange juice fortified with calcium citrate malate (CCM).

OBJECTIVE: Determine calcium (Ca) absorption from Ca fortified orange and apple juice. METHODS: Absorbability was assessed by measuring 45Ca absorption in healthy women (mean age 57 years, n = 57/group) and whole body 47Ca retention in adult female beagle dogs (n = 6/group) and young adult male rats (n = 6/group). Women received 6.24 mmol (250 mg) Ca as calcium citrate malate fortified orange juice (CCM-OJ) or apple juice (CCM-AJ). Dogs received 3.12 mmol (125 mg) Ca as CCM-OJ or CCM-AJ. Rats were administered 0.15 mmol (6 mg) Ca as either milk, CCM-OJ, or CCM-AJ. Additional 47Ca whole body retention experiments in rats measured the effects of differences in the carbohydrate and organic acid contents of the juices on Ca absorption. RESULTS: Mean +/- SEM percent Ca fractional absorption was greater (p < 0.003) in women who consumed CCM-AJ (42 +/- 2%) than those who consumed CCM-OJ (36 +/- 1%). Ca retention in dogs was 15 +/- 1% for CCM-OJ and 29 +/- 2% for CCM-AJ (p < 0.001). Ca retention was significantly different (p < 0.05) in rats administered milk (42 +/- 2%), CCM-OJ (52 +/- 2%), or CCM-AJ (61 +/- 2%). By manipulating the carbohydrate and organic acid concentrations of test solutions to mimic the composition of Ca fortified juices, we found that the greater fructose and lower organic acid content of apple juice accounted for its greater Ca absorbability. CONCLUSIONS: CCM fortified versions of orange and apple juice have high Ca absorbability and are potentially important vehicles for increasing dietary Ca intake. The greater Ca absorption from CCM-AJ compared with CCM-OJ is accounted for by differences in the carbohydrate and organic acid content of the juices. These data suggest that by modifying common beverage ingredients, products with even greater Ca absorbability could be formulated.

Absorption↗

PubMed1996

Magnesium balance in adolescent females consuming a low- or high-calcium diet.

Increasing emphasis is being placed on optimizing calcium intake during growth as a way to enhance peak bone mass. Although some studies in adults have shown that high calcium intake may negatively affect magnesium utilization, few data are available regarding the interaction of calcium and magnesium in healthy children. The purpose of our study was to measure the effect of calcium intake on magnesium balance in 26 adolescent girls (mean age 11.3 y) during a 14-d period. Subjects ate a controlled basal diet containing 667 mg Ca and 176 mg Mg. In addition to the basal diet, subjects were randomly assigned in a double-blind fashion to consume 1000 mg elemental Ca/d as calcium citrate malate or a placebo. Magnesium use did not differ between the low-calcium and high-calcium groups as measured by absorption (50% compared with 55%), urinary excretion (70 compared with 74 mg/d), and fecal excretion (88 compared with 79 mg/d). Accordingly, magnesium balance was not different in subjects consuming 667 or 1667 mg Ca/d and averaged 21 mg Mg/d for the whole study group. Magnesium balance was significantly correlated with magnesium intake (r = 0.511, P = 0.008) and magnesium absorption (r = 0.723, P < 0.001). Prediction intervals from the regression of magnesium balance on intake indicated that the current recommended dietary allowance of magnesium would result in magnesium balance > or = 8.5 mg/d in 95% of the girls. This value appears consistent with long-term accretion rates needed to account for the expansion of the total-body magnesium pool during growth. In summary, our observations support the adequacy of the current recommended dietary allowance for magnesium and indicate that alterations in magnesium utilization should not be anticipated in adolescent females consuming a high-calcium diet.

Absorption↗

PubMed1995

Effect of calcium supplementation on blood pressure in children.

OBJECTIVE: To evaluate the effect of calcium supplementation on blood pressure in children. DESIGN: Randomized, double-masked, placebo-controlled trial. SETTING AND PARTICIPANTS: One hundred one fifth-grade students in one inner-city school. INTERVENTION: Each child consumed 480 ml of juice beverages, containing either no calcium or 600 mg calcium (as calcium citrate malate) daily for 12 weeks. MEASUREMENTS: At baseline we obtained nutrient data from three sets of 2-day food records on each subject. We measured blood pressure four times on each of three weekly sittings at baseline and at follow-up. Using multiple linear regression analysis, we compared mean blood pressure change in the intervention group with that in the placebo group. RESULTS: There were 50 girls and 51 boys; 61 subjects were black. At baseline, mean age was 11.0 years, systolic and diastolic blood pressures were 101.7 and 57.7 mm Hg, daily total energy intake was 1966 kcal, and calcium intake was 827 mg. With control for age, height, hours of television watched, and baseline blood pressure, systolic blood pressure increased 1.0 mm Hg in the intervention group and 2.8 mm Hg in the placebo group (effect estimate = -1.8 mm Hg; 95% confidence interval -4.0, 0.3). In black subjects the intervention effect estimate was -2.0 mm Hg (95% confidence interval -4.4, 0.4). From lowest to highest quartile of baseline calcium intake (per 1000 kcal), the intervention effect estimates were -3.5, -2.8, -1.3, and 0.0 mm Hg (p for trend = 0.009). There was little effect on diastolic blood pressure. CONCLUSION: These data suggest a blood pressure-lowering effect of calcium supplementation in children, especially in subjects with low baseline calcium intake.

Beverages↗

PubMed1995

Urinary calcium, sodium, and bone mass of young females.

Calcium is an important determinant of peak bone mass in young adults because of its influence on skeletal development during growth. Attainment of maximum peak bone mass requires optimal positive balance between calcium intake and obligatory losses of calcium, primarily in urine and feces. Urinary excretion is an important determinant of calcium retention in the body. Accordingly, the purpose of this study was to evaluate the influence of various nutrients on urinary calcium excretion, and to assess their impact on bone mass of young females, aged 8-13 y, during early puberty. The study was conducted in 381 healthy white females in pubertal stage 2. From each participant we collected basic anthropometric measurements, a 3-d food record, blood, a 24-h urine sample, and bone mass measurements of the total body and forearm by dual X-ray absorptiometry. Urinary sodium was found to be one of the most important determinants of urinary calcium excretion: [urinary calcium (mmol/d) = 0.01154 x urinary sodium (mmol/d) + 0.823], whereas calcium intake had relatively little impact: [urinary calcium (mmol/d) = 0.02252 x calcium intake (mmol/d) + 1.5261]. Urinary calcium was much higher at a calcium intake of approximately 37.5 mmol/d (1500 mg/d), supporting the notion that calcium is a threshold nutrient. Calcium intake had a significant positive influence on the bone mineral content and density of the whole body and radius shaft whereas urinary calcium had a negative influence, presumably by reducing calcium accretion into the skeleton.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

PubMed1994

Spinal bone loss in postmenopausal women supplemented with calcium and trace minerals.

The effects of calcium supplementation (as calcium citrate malate, 1000 mg elemental Ca/d) with and without the addition of zinc (15.0 mg/d), manganese (5.0 mg/d) and copper (2.5 mg/d) on spinal bone loss (L2-L4 vertebrae) was evaluated in healthy older postmenopausal women (n = 59, mean age 66 y) in a 2-y, double-blind, placebo-controlled trial. Changes (mean +/- SEM) in bone density were -3.53 +/- 1.24% (placebo), -1.89 +/- 1.40% (trace minerals only), -1.25 +/- 1.46% (calcium only) and 1.48 +/- 1.40% (calcium plus trace minerals). Bone loss relative to base-line value was significant (P = 0.0061) in the placebo group but not in the groups receiving trace minerals alone, calcium alone, or calcium plus trace minerals. The only significant group difference occurred between the placebo group and the group receiving calcium plus trace minerals (P = 0.0099). These data suggest that bone loss in calcium-supplemented, older postmenopausal women can be further arrested by concomitant increases in trace mineral intake.

Aged↗

PubMed1994

Supplementation trials with calcium citrate malate: evidence in favor of increasing the calcium RDA during childhood and adolescence.

The vast majority of peak adult bone mass is accumulated by the time longitudinal growth is complete. As peak bone mass is an important determinant of future fracture risk, the goal of the current calcium recommended dietary allowance during youth is to provide a calcium intake that allows individuals to reach their full genetic potential for acquiring skeletal mass. The advent of controlled trials of calcium supplementation and total body bone mass measurements in children and adolescents provide the first direct way of determining the amount of calcium necessary to achieve optimal skeletal accretion. These studies indicate that the current RDAs are insufficient to support optimal bone mass gain during growth and development. Based on the recent intervention trials, recommendations are made for an RDA of 1250 mg during childhood and 1450 mg during adolescence. These values are consistent with established calcium balance intake thresholds for growth during pre-adolescence and adolescence.

Adolescent↗

PubMed1994

Timing of peak bone mass in Caucasian females and its implication for the prevention of osteoporosis. Inference from a cross-sectional model.

To determine the timing of peak bone mass and density, we conducted a cross-sectional study of bone mass measurements in 265 premenopausal Caucasian females, aged 8-50 yr. Bone mass and bone mineral density were measured using dual X-ray absorptiometry and single-photon absorptiometry at the spine (anteroposterior, lateral), proximal femur, radius shaft, distal forearm, and the whole body. Bone mass parameters were analyzed using a quadratic regression model and segmented regression models with quadratic-quadratic or quadratic-linear form. The results show that most of the bone mass at multiple skeletal locations will be accumulated by late adolescence. This is particularly notable for bone mineral density of the proximal femur and the vertebral body. Bone mass of the other regions of interest is either no different in women between the age of 18 yr and the menopause or it is maximal in 50-yr-old women, indicating slow but permanent bone accumulation continuing at some sites up to the time of menopause. This gain in bone mass in premenopausal adult women is probably the result of continuous periosteal expansion with age. Since rapid skeletal mineral acquisition at all sites occurs relatively early in life, the exogenous factors which might optimize peak bone mass need to be more precisely identified and characterized.

Adolescent↗

PubMed1993

Calcium supplementation and bone mineral density in adolescent girls.

OBJECTIVE: To evaluate the effect of calcium supplementation on bone acquisition in adolescent white girls. DESIGN: A randomized, double-blind, placebo-controlled trial of the effect of 18 months of calcium supplementation on bone density and bone mass. SUBJECTS: Ninety-four girls with a mean age of 11.9 + 0.5 years at study entry. SETTING: University hospital in a small town. INTERVENTIONS: Calcium supplementation, 500 mg/d calcium as calcium citrate malate; controls received placebo pills. MAIN OUTCOME MEASURES: Bone mineral density and bone mineral content of the lumbar spine and total body were measured by dual-energy x-ray absorptiometry and calcium excretion from 24-hour urine specimens. RESULTS: Calcium intake from dietary sources averaged 960 mg/d for the entire study group. The supplemented group received, on average, an additional 354 mg/d of calcium. The supplemented group compared with the placebo group had greater increases of lumbar spine bone density (18.7% vs 15.8%; P = .03), lumbar spine bone mineral content (39.4% vs 34.7%; P = .06), total body bone mineral density (9.6% vs 8.3%; P = .05), and 24-hour urinary calcium excretion (90.4 vs 72.9 mg/d; P = .02), respectively. CONCLUSIONS: Increasing daily calcium intake from 80% of the recommended daily allowance to 110% via supplementation with calcium citrate malate resulted in significant increases in total body and spinal bone density in adolescent girls. The increase of 24 g of bone gain per year among the supplemented group translates to an additional 1.3% skeletal mass per year during adolescent growth, which may provide protection against future osteoporotic fracture.

Absorptiometry, Photon↗

PubMed1993

Breast milk chromium and its association with chromium intake, chromium excretion, and serum chromium.

Chromium metabolism of lactating women was evaluated by measuring diet, breast milk, urine, and serum chromium in 17 subjects 60 d postpartum. Breast milk chromium concentration was similar for the 3 d of collection with a mean +/- SE concentration of 3.54 +/- 0.40 nmol/L (0.18 ng/mL). Dietary intake and urinary chromium values were also similar for each of the 3 collection days. Total chromium intake of lactating mothers (0.79 +/- 0.08 mumol/d) was greater than that of reference female subjects (0.48 +/- 0.02). There was a significant correlation (r = 0.84) between serum chromium and urinary chromium excretion. If a breast milk volume of 715 mL is assumed, chromium intake of exclusively breast-fed infants is < 2% of the estimated safe and adequate daily intake of 10 micrograms. In summary, breast milk chromium content is independent of dietary chromium intake and serum or urinary chromium values. Chromium intake also did not correlate with serum or urine chromium but there was a significant relationship between serum and urinary chromium concentrations.

Adolescent↗

PubMed1993

Intraduodenal delivery of intrinsically and extrinsically labelled CaCO3 in the rat: effect of solubilization on calcium bioavailability.

The dissolution of CaCO3 before intraduodenal administration was found to be an important factor determining calcium (Ca) bioavailability. Extrinsically and intrinsically labelled 47CaCO3 preparations were sequentially dissolved by serial additions of HCl. Aliquots of these preparations were collected before (no HCl added) and during the solubilization process and administered intraduodenally to rats. Whole body 47Ca retention 72 h post-dose was used as a measure of Ca bioavailability. Although dissolution of CaCO3 significantly increased Ca bioavailability (P < 0.001), Ca from both intrinsically and extrinsically labelled CaCO3 was absorbed and retained to some extent without prior acid dissolution. Due to a disproportionately high concentration of 47Ca on the particle surface, extrinsically labelled 47CaCO3 overestimated bioavailability when unsolubilized or partially solubilized CaCO3 preparations were used (P < 0.05). These data indicate that dissolution is a determining factor for Ca bioavailability from CaCO3. Incomplete dissolution will significantly limit but not completely prevent Ca bioavailability. The disintegration and dissolution characteristics of commercial CaCO3 preparations, which vary widely, may produce important differences in Ca absorption.

Animals↗

PubMed1993

Effect of age, calcium source, and radiolabeling method on whole body 47Ca retention in the rat.

In a longitudinal study we determined the effect of animal age as well as Ca source and radiolabeling method on Ca bioavailability by measuring whole body 47Ca retention (WBR) in male Sprague-Dawley rats. The WBR assay was performed without surgery or anesthesia, and the same groups of animals were studied at 8, 16, 20, and 32 wk of age. Rats were administered a 6-mg radiolabeled oral dose of Ca as Ca citrate malate (CCM) or intrinsically or extrinsically labeled CaCO3 or hydroxyapatite (HAP). Fractional Ca retention was measured from the 72-h postdose WBR divided by WBR at time 0. WBR was significantly affected by Ca source with CCM > CaCO3 > HAP at all ages (P < 0.001). The rank order and relative bioavailabilities of these Ca salts in the rat model agreed well with literature values for Ca absorption in adult humans. Although percent WBR decreased significantly with advancing age (P < 0.001), the mean rate of decline (-3.4%/wk) was not affected by Ca source. Extrinsic radiolabeling overestimated (approximately 20%) Ca bioavailability when the rats were young. However, the magnitude of this effect diminished with advancing animal age and was not significant across all ages (repeated measures analysis of variance P = 0.10).

Administration, Oral↗

PubMed1992

Determinants of bone density in young women. I. Relationships among pubertal development, total body bone mass, and total body bone density in premenarchal females.

Bone mass accretion during puberty appears to be critical in the development of peak bone mass, which, in turn, is believed to be a major determinant of osteoporosis risk. Although genetics may be the primary determinant of peak bone mass, modifiable secondary factors, such as nutrition and hormone exposure, may significantly affect bone mass accretion during the second decade of life. As part of a longitudinal study of major determinants of bone development during puberty, we obtained cross-sectional measurements from 112 premenarchal caucasian females (mean +/- SD age, 11.9 +/- 0.49 yr at study entry). Total body bone mineral density (TBBMD) and total body bone mineral content (TBBMC) were measured by dual energy x-ray absorptiometry and compared to anthropometric, pubertal development, urinary steroid and gonadotropin levels, and nutrient intake. An integrated estrogen exposure index was developed and used to evaluate the cumulative effect of circulating estrogen levels on both development. Compared to normative reference data for adults, our subjects possessed 90% of adult height, 68% of adult weight, 83% of adult TBBMD, and 53% of TBBMC. The strongest combined predictors of prepubertal TBBMD and TBBMC were body weight, followed by height and pubertal development. Urinary estradiol levels were positively correlated with dietary intake of iron and vitamin B6.

Adolescent↗

PubMed1991

Vitamin B-6 metabolism in premature infants.

The response of premature infants to intravenous pyridoxine or pyridoxal was studied by measuring serum and erythrocyte pyridoxal 5'-phosphate (PLP). In the first study serum PLP was measured in 28 infants periodically through day 28. Infants less than 30 wk gestational age (GA) had no serum PLP response to the administration of pyridoxine. Infants greater than or equal to 30 wk GA had significantly greater concentrations of PLP by day 3. In the second study there was a negligible response of serum PLP in nine infants less than or equal to 28 wk GA to supplementation of pyridoxine or pyridoxal. However, erythrocyte PLP and whole-blood total vitamin B-6 concentrations increased in both groups, indicating the presence of a substantial amount of the vitamin in the circulation of the infants. Whereas the functional significance of these observations is not known, it appears that in premature infants, serum PLP may not be an appropriate indicator of vitamin B-6 status.

Erythrocytes↗

PubMed1991

Spinal bone density and calcium intake in healthy postmenopausal women.

Dietary calcium intake and bone mineral density (BMD) of the lumbar spine (L2-L4) were determined in 131 healthy free-living postmenopausal women (aged 64.7 +/- 7.6 y, means +/- SD). The calcium consumption for the total population was 606 +/- 302 mg/d. Subjects consuming less than the population mean of dietary calcium had significantly lower BMDs than did subjects with intakes above the mean (P less than 0.009); these two groups did not differ in basic demographic characteristics. Additional analyses using a stepwise univariate regression model demonstrated that BMD was significantly associated with body weight (P less than 0.001) and dietary calcium intake (P less than 0.02). These data support the hypothesis that dietary calcium intake is a determinant of skeletal health in postmenopausal women.

Aged↗

PubMed1991

Nutrient intake variability in a pediatric population: implications for study design.

Estimates of an individual's intake of specific nutrients is important in epidemiologic investigations of disease-diet relationships. The object of the present investigation was to determine the minimum number of daily food records required to estimate intake of specific nutrients in children. Both members of 70 pairs of twins (n = 140 children) completed a minimum of 3 and a maximum of 23 food records throughout a 2-y period. All subjects were white and range in age from 5 to 14 y. Assuming an attenuation of the correlation coefficient of 80%, the minimum number of daily food records required to estimate energy intake was seven for boys and eight for girls. As a group, the vitamin intakes were the most variable for both boys and girls, often requiring more than 20 records for either sex. Requirements for other nutrients generally fell between these two extremes. The results of the present investigation are particularly relevant to the interpretation and design of studies of associations with nutrient intake.

Adolescent↗