Calcium and magnesium balance in 9-14-y-old children

Few data are available regarding calcium and magnesium absorption and endogenous fecal excretion in children. We used a multitracer stable isotope technique to assess calcium and magnesium balance in 12 boys and 13 girls aged 9-14 y (mean weight: 42 kg) maintained on relatively high calcium intakes (mean: 1310 +/- 82 mg/d). There were no significant differences in absorption of calcium or magnesium from milk between boys and girls. Calcium retention (balance) correlated positively with calcidiol (25-hydroxyvitamin D) concentration (r = 0.48, P = 0.02) and serum alkaline phosphatase activity (r = 0.44, P = 0.03). There was no significant relation between magnesium balance and concentration. When data from this study were combined with our previously reported data, an increase in total calcium absorption was seen for pubertal (Tanner stages 2-4) but not prepubertal (Tanner stage 1) white children over the range of intakes from approximately 750 to 1350 mg/d. Despite intakes similar to the 1989 recommended dietary allowance for magnesium (mean intake: 6.4 +/- 1.2 mg.kg-1.d-1), 11 of the 25 subjects (6 girls and 5 boys) were in negative magnesium balance. We conclude that benefits from higher calcium intakes, < or = 1350 mg/d, were most apparent in pubertal children. In addiction, higher magnesium intakes should be considered for children.     

Zinc metabolism and requirement in Chinese preschool children consuming different diets

Zinc metabolism of children differs due to diet and this can affect zinc requirement. We used the balance method to study zinc metabolism in 11 Chinese preschool children (six males and five females, 5.5-6.5 y old with a mean age of 6 y) of normal zinc status as judged by comprehensive criteria before and after they were fed a balanced diet. Zinc intakes and excretions via feces, urine, whole body surface and hair were determined in each subject. After all subjects consumed a balanced diet for 3 wk, losses of zinc in feces and urine increased from 3.77 +/- 0.62 mg/d to 5.28 +/- 0.92 mg/d (P < 0.05) and 0.19 +/- 0.05 mg/d to 0.23 +/- 0.05 mg/d (P < 0.05), respectively, as dietary zinc intakes increased from 5.38 +/- 0.71 mg/d to 7.12 +/- 0.64 mg/d (P < 0.05). Whole body surface zinc loss did not change (0.25 +/- 0.07 mg/d vs 0.27 +/- 0.09 mg/d (P = 0.57). Hair zinc loss was 5.26 +/- 2.49 microgram/d. Post-treatment, zinc excretions via feces, urine and whole body surface positively correlated with dietary zinc intakes (0.68-0.88, P < 0.05). Zinc retention did not change (1.17 +/- 0.78 mg/d vs 1.35 +/- 0.52 mg/d, P = 0.53) with balanced diet treatment. After treatment zinc metabolism in these children was positive and stable. The absorbed zinc, 1.84 +/- 0.47 mg/d, was considered their absolute zinc requirement. Assuming that zinc availability is 20%, the zinc requirement in the daily diet of Chinese preschool children should be 9.23 +/- 2.35 mg/d (6.88-11.58 mg/d).     

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.     

Biochemical effects of calcium supplementation in postmenopausal women: influence of dietary calcium intake

We studied the biochemical effects of calcium supplementation during a 2-mo course in postmenopausal women (x +/- SD: 64 +/- 5 y of age and 14.5 +/- 6.7 y since menopause). The effects on calcium homeostasis and bone remodeling were assessed after 1 and 2 mo of daily administration of either calcium carbonate (1200 mg elemental Ca/d, n = 60) or a placebo (n = 56). The daily dietary calcium intake assessed before the beginning of calcium supplementation was 786 mg/d. We found a significant inverse relation between baseline intact parathyroid hormone (iPTH) and dietary calcium intake before supplementation (r = -0.48, P = 0.0002). A significant increase in urinary excretion of pyridinoline was observed when the dietary calcium intake was lower than the median value. Calcium supplementation resulted in a significant increase in 24-h urinary calcium (39%, P < 0.02) and a significant reduction of bone alkaline phosphatase at 2 mo and of all bone-resorption markers (hydroxyproline, pyridinoline, and deoxypyridinoline) at I and 2 mo without significant changes in 44-68 PTH fragments or iPTH concentrations. When the dietary calcium intake was low (mean +/- SD: 576 +/- 142 mg/d), calcium supplementation was responsible for a greater increase in urinary calcium excretion and a greater decrease in markers of bone turnover. The greatest variations were observed for deoxypyridinoline at 1 and 2 mo (-18.5%, P < 0.05) and for pyridinoline at 1 mo (-16.3%, P < 0.01). Two months of calcium supplementation in postmenopausal women was efficient in reducing markers of bone turnover, with a greater effect in women with a low dietary calcium intake.     

Decline and recovery of olfactory receptor expression following unilateral bulbectomy

Zinc absorption, mineral balance, and blood lipid concentrations were measured in 21 women aged 33 +/- 7 y (range: 20-42 y) consuming controlled lactoovovegetarian and nonvegetarian diets for 8 wk each in a crossover design. The lactoovovegetarian and nonvegetarian diets, respectively, provided (by analysis) 973 and 995 mg Ca, 1.8 and 1.3 mg Cu, 367 and 260 mg Mg, 5.9 and 2.5 mg Mn, 1457 and 1667 mg P, 9.1 and 11.1 mg Zn, and (by calculation) 40 and 16 g dietary fiber, 2.5 and 0.8 mmol phytic acid, molar ratios of phytate to Zn of 14 and 5, and millimolar ratios of (phytate x Ca) to Zn of 344 and 111. Dietary zinc absorption was measured by extrinsic isotopic labeling and whole-body counting. Plasma cholesterol, cholesterol fractions, and lipoproteins were reduced 7-12% with the lactoovovegetarian diet, consistent with predictions based on dietary cholesterol and fat. Blood pressure was unaffected. Calcium, copper, magnesium, and phosphorus balances were not different between diets; manganese balance tended to be greater with the lactoovovegetarian diet (P < 0.07). The lactoovovegetarian diet was associated with a 21% reduction in absorptive efficiency that, together with a 14% reduction in dietary zinc, reduced the amount of zinc absorbed by 35% (2.4 compared with 3.7 mg/d) and reduced plasma zinc by 5% within the normal range. Zinc balance was maintained with both diets. Although there is a greater risk of zinc deficiency in persons consuming lactoovovegetarian compared with omnivorous diets, with inclusion of whole grains and legumes zinc requirements can be met and zinc balance maintained.     

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.     

Serum zinc in highly trained adolescent gymnasts

Serum zinc was measured in 20 adolescent gymnasts (9 boys, 11 girls, age 12-15 yr) explored for detecting possible adverse effects of intense training on pubertal maturation and growth. They had low serum zinc (0.599 +/- 0.026 mg/L) when compared to matched control sedentary children (n = 118 mean 0.81 +/- 0.014 p < 0.001). Girls had lower zinc than boys (0.557 +/- 0.023 vs 0.651 +/- 0.044 p < 0.001). Zinc was correlated to isometric adductor strength (r = 0.468 p < 0.05). Children with serum zinc < 0.6 mg/L had lower insulin-like growth factor binding protein 3 than others (2.326 +/- 0.264 vs 2.699 +/- 0.12 p < 0.01). Thus, zinc is lowered in trained adolescent gymnasts and even lower in females. This reduction could play some role in abnormalities of puberty, growth, or muscular performance.     

Bepridil reducing levothyroxine-induced enhancement of mitochondria Ca2+ Mg(2+)-ATPase activity in rat cerebrum

AIM: To study if bepridil (Bep) could affect the enhancement of activity of cerebral mitochondria Ca2+ Mg(2+)-ATPase caused by levothyroxine (Lev) in relation to ischemic overload calcium cerebrum injury. METHODS: The experimental hyperthyroidism model with ischemic cerebrum was developed in rats by ig Lev 1 mg.kg-1.d-1 for 7 d. Ca2+ Mg(2+)-ATPase activity and its kinetic parameters were assayed. RESULTS: The activity, Vmax and Km of cerebral mitochondria Ca2+ Mg(2+)-ATPase in control rats were 3.1 +/- 0.8, 5.1 +/- 2.3 mmol.P(i).h-1/g protein and 0.81 +/- 0.08 mmol.L-1 (ATP) respectively, whereas those of hyperthyroid rats were significantly altered to 4.6 +/- 0.5, 8.5 +/- 1.9 mmol.P(i).h-1/g protein and 0.49 +/- 0.11 mmol.L-1 (ATP) respectively. After treated with Bep 10 or 20 mg.kg-1.d-1 ig for 3 d, allabove 3 parameters of the enzyme were very significantly reduced vs those of either control or hyperthyroid. CONCLUSION: Bep, via decreasing Ca2+ Mg(2+)-ATPase activity and increasing the affinity of Ca2+ Mg(2+)-ATPase to ATP, could prevent rat cerebrum from ATP depletion and ischemic overload calcium injury.     

Association of nucleoside diphosphate kinase nm23-H2 with human telomeres

In this study, the effect of dietary calcium and vitamin D on serum parathyroid hormone and vitamin D metabolites was measured in 376 free-living women aged 65-77 y. Mean calcium intake in both groups was close to the recommended dietary allowance of 800 mg/d. Mean vitamin D intake in the 245 women not taking vitamin D supplements was 3.53 microg/d (141 IU/d), which is below the recommended dietary allowance of 5 microg/d (200 IU/d). To test the hypothesis that vitamin D is more important than calcium in reducing serum parathyroid hormone, the source of dietary calcium intake was subdivided into milk, which is fortified with vitamin D, and nonmilk sources. The serum parathyroid hormone concentration was inversely correlated with calcium intake derived from milk (r = -0.20, P < 0.01) but not from nonmilk sources (r = -0.06). Furthermore, serum calcidiol correlated with milk calcium intake (r = 0.35, P < 0.001) but not with nonmilk calcium intake (r = 0.10). Multivariate analysis showed a significant effect of season on serum calcidiol but not on serum parathyroid hormone. Serum parathyroid hormone was inversely correlated with serum calcidiol (r = -0.33, P < 0.001) and the regression predicted that mean serum parathyroid hormone would be reduced in the elderly to concentrations considered normal in the young when serum calcidiol is 122 nmol/L (49 ng/mL); this would require a much higher recommended dietary allowance for vitamin D than 5 microg/d (200 IU/d).     

Biochemical markers of calcium and bone metabolism during 18 months of lactation in Gambian women accustomed to a low calcium intake and in those consuming a calcium supplement

The effect of 18 months of lactation on indexes of calcium and bone metabolism was studied in 60 Gambian women accustomed to a very low calcium intake. Half the women consumed a calcium supplement from 10 days postpartum for 52 weeks (supplement, 714 mg Ca/day; total Ca intake, 992 +/- 114 mg/day), and half consumed placebo (total Ca intake, 288 +/- 128 mg/day). Fasting blood and 24-h urine samples were collected at 1.5, 13, 52, and 78 weeks of lactation and analyzed for calciotropic hormones (intact PTH, 1,25-dihydroxyvitamin D, and calcitonin), bone turnover markers (osteocalcin, bone alkaline phosphatase, and urinary deoxypyridinoline), and plasma minerals (calcium and phosphate). The first months of lactation were associated with increased bone turnover and plasma phosphate, and decreased PTH and 1,25-dihydroxyvitamin D. These effects diminished by 52 weeks, although breast milk volumes remained high. The Gambians had higher PTH, 1,25-dihydroxyvitamin D, and bone formation than British women with a greater customary calcium intake. None of the biochemical indexes was affected by calcium supplementation, with the possible exception of bone alkaline phosphatase (-29% at 52 weeks; P = 0.015). These data demonstrate that lactation-associated changes in calcium and bone metabolism are physiological and are independent of dietary calcium supply in women with very low calcium intakes.     

Dietary calcium, calcium supplementation, and blood pressure in African American adolescents

BACKGROUND: Intake of calcium from the diet is inversely associated with blood pressure in observational studies and animal models but randomized trials in humans have found only small effects of calcium supplementation on blood pressure. A blood pressure-lowering effect of calcium supplementation may thus be restricted to persons with a low intake of calcium from the diet and specific genetic or other characteristics. OBJECTIVE: A randomized trial was conducted to assess the effect of calcium supplementation on blood pressure in African American adolescents. Rapid growth during adolescence may increase calcium requirements, and avoidance of milk and milk products by some African Americans can result in low intake of calcium. DESIGN: One hundred sixteen adolescents (65 girls, 51 boys; mean age: 15.8 y) were given calcium (1.5 g/d) or placebo for 8 wk in a randomized, double-blind, crossover design. Blood pressure was measured after 2, 4, and 8 wk. Dietary calcium was determined with a validated food-frequency questionnaire. RESULTS: The net effect (+/-SE) of calcium supplementation on diastolic blood pressure was a reduction of 1.9 +/- 1.1 mm Hg (P = 0.04, one-tailed t test). Blood pressure reduction was greater in adolescents with lower intake of calcium from the diet (P = 0.003, one-tailed t test for interaction): -4.9 +/- 1.6, -2.3 +/- 1.6, and 1.4 +/- 1.8 mm Hg for change in the lower (0.024-0.067 g Ca/MJ), middle (0.069-0.091 g Ca/MJ), and upper (0.093-0.217 g Ca/MJ) tertiles, respectively. No main effect on systolic blood pressure was detected. CONCLUSION: These findings suggest that calcium supplementation may lower diastolic blood pressure in African American adolescents with low dietary intakes of calcium.     

Health care coverage and access for children in an urban state: the New York perspective

To clarify the role of the intestine, kidney, and bone in maintaining calcium homeostasis during pregnancy and lactation and after the resumption of menses, a longitudinal comparison was undertaken of 14 well-nourished women consuming approximately 1200 mg Ca/d. Measurements were made before conception (prepregnancy), once during each trimester of pregnancy (T1, T2, and T3), early in lactation at 2 mo postpartum (EL), and 5 mo after resumption of menses. Intestinal calcium absorption was determined from the enrichment of the first 24-h urine sample collected after administration of stable calcium isotopes. Bone mineral of the total body and lumbar spine was measured by dual-energy X-ray absorptiometry and quantitative computerized tomography, respectively. Twenty-four-hour urine and fasting serum samples were analyzed for calcium, calcitropic hormones, and biochemical markers of bone turnover. Despite an increase in calcium intake during pregnancy, true percentage absorption of calcium increased from 32.9+/-9.1% at prepregnancy to 49.9+/-10.2% at T2 and 53.8+/-11.3% at T3 (P < 0.001). Urinary calcium increased from 4.32+/-2.20 mmol/d at prepregnancy to 6.21+/-3.72 mmol/d at T3 (P < 0.001), but only minor changes in maternal bone mineral were detected. At EL, dietary calcium and calcium absorption were not significantly different from that at prepregnancy, but urinary calcium decreased to 1.87+/-1.22 mmol/d (P < 0.001) and trabecular bone mineral density of the spine decreased to 147.7+/-21.2 mg/cm3 from 162.9+/-25.0 mg/cm3 at prepregnancy (P < 0.001). Calcium absorption postmenses increased nonsignificantly to 36.0+/-8.1% whereas urinary calcium decreased to 2.72+/-1.52 mmol/d (P < 0.001). We concluded that fetal calcium demand was met by increased maternal intestinal absorption; early breast-milk calcium was provided by maternal renal calcium conservation and loss of spinal trabecular bone, a loss that was recovered postmenses.     

The human mast cell line HMC-1 binds and responds to C3a but not C3a(desArg)

OBJECTIVE: To evaluate the breakfast intake of calcium and milk products and to determine whether these correlate with total intake of both calcium and milk products. METHODS: Food taken at breakfast and throughout the day was recorded using a 7 consecutive day food record in 200 schoolchildren aged between 9 and 13 years. RESULTS: 65.3% of boys and 80.5% of girls showed intakes of calcium which were lower than recommended. Milk products were the foods most frequently included in breakfast (95.5% of subjects included them in this meal). A relationship was seen between energy provided by breakfast and the quantities of milk products (r = 0.5735) and calcium (r = 0.6908) taken at this meal. A relationship was also seen between energy provided by breakfast and daily intake of milk products (r = 0.4633) and calcium (r = 0.4954). The percentage of intakes of calcium lower than those recommended decreased when breakfast provided > or = 20% of total energy intake, and when the consumption of milk products at breakfast was greater than the 50th percentile (200 ml). Subjects with breakfast milk product intakes > or = 200 ml showed higher intakes of the same over the rest of the day (233.3 +/-140.4 g) than did those who took lesser quantities of these foods at breakfast (161.5 +/- 100.6 g). Further, those who took > or = 25% of the recommended intake of calcium at breakfast showed greater intakes of the same over the rest of the day (600.4 +/- 213.8 mg compared to 510.8 +/- 200.7 mg in subjects with lower calcium intakes). CONCLUSIONS: The intake of milk products (r = 0.7587) and calcium (r = 0.7223) at breakfast correlates with the consumption of these foods in the whole diet. However, the total daily intake of milk products and calcium does not depend solely on breakfast intake. Subjects with the greatest intakes at breakfast also showed greater intakes over the rest of the day (r = 0.3953 for milk products and r = 0.4122 for calcium).     

Reduced expression of the renal calcium-sensing receptor in rats with experimental chronic renal insufficiency

Chronic renal insufficiency is associated with elevated serum parathyroid hormone (PTH) levels (2 degrees HPT), deficiency of 1,25-dihydroxyvitamin D (1,25(OH)2D), and hypocalciuria. In chronic renal insufficiency, the 2 degrees HPT may result from reduced expression of the parathyroid gland extracellular Ca(2+)-sensing receptor (CaSR). Since the CaSR was cloned from rat and human kidney, this study examined in rats whether expression of the renal CaSR is altered in experimental chronic renal insufficiency. Four weeks after chronic renal insufficiency was induced by 5/6 nephrectomy (Nx) in Sprague Dawley rats, the serum creatinine concentration was 0.96+/-0.06 mg/dl compared with 0.35+/-0.02 mg/dl in sham-operated animals (P < 0.05). The serum total Ca2+ and phosphorus concentrations were not different. In the Nx group, the serum concentration of amino-PTH was higher (65+/-8 pg/ml), and the concentration of 1,25(OH)2D was significantly lower (47+/-5 pg/ml) compared with 45+/-5 pg/ml and 61+/-4 pg/ml (P = 0.05) in the sham group, respectively. In a subset of rats studied, the Nx group was hypocalciuric (1.4+/-0.5 mg/kg per d) compared with the sham group (3.7+/-0.5 mg/kg per d) (P < 0.05). In the Nx rats, CaSR mRNA expression and CaSR protein levels were found to be reduced by 35 and 38%, respectively, than those observed in controls. These results suggest that reduced renal CaSR expression in chronic renal insufficiency may play a role in disordered mineral ion homeostasis, including hypocalciuria.     

Taxonomic review of Cotingacola (Phthiraptera: Philopteridae) from the cotingas (Passeriformes: Tyrannidae), with descriptions of two new species

PURPOSE: The purpose of this study was to discuss, in the light of the results of a survey, the calcium ration of a sample of French youth and to determine whether various sports activities can be related to dietary calcium intake. METHODS: Physical activity was evaluated using Baecke's questionnaire. Calcium intake was evaluated using a food frequency oriented questionnaire. The survey was performed on a population of 10,373 subjects (6,966 males and 3,407 females) including three different groups of subjects: school children and college students, military personnel, and athletes registered in sports federations. The mean age of this population was 19 +/- 9 yr, ages ranging between 7 and 50 yr. RESULTS: The mean amount of declared calcium intake (DCI) for the total population was 1242 +/- 843 mg per 24 hr (mg x d(-1)). Fifty percent of this population consumed less than 1000 mg x d(-1) and 13% less than 500 mg x d(-1). There was no significant relationship between the index of activity and declared calcium intake. Calcium intake decreased with age and was lower in females compared to males. CONCLUSIONS: The subjects trained in individual endurance sports such as triathlon, biking, and road running have a lower DCI than subjects trained in team sports such as volley ball, handball, or basketball. This survey, performed on a large population, does indicate that for half of them daily calcium intake is below the threshold of 1,000 mg x d(-1) considered the daily requirement covering the needs of a population without age or gender distinction and that calcium intake is not related to the level of physical activity.     

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)     

Pharmacological classification of adenosine receptors in the sinoatrial and atrioventricular nodes of the guinea-pig

Factors influencing the change in bone mineral after 3 mo of lactation were investigated in 47 breast-feeding mothers, 11 formula-feeding mothers, and 22 nonpregnant, nonlactating control subjects. At 6-8 wk postpartum, the breast-feeding group had a mean (+/-SD) calcium intake of 34.8+/-13.2 mmol/d and breast-milk volume, calcium concentration, and calcium output of 0.865+/-0.230 L/d, 7.41+/-1.25 mmol/L, and 6.41+/-2.00 mmol/d, respectively. There was no relation between calcium intake and any breast-milk variable. Dual-energy X-ray absorptiometry of the whole body, spine, hip, and forearm was performed at 0.5 and 3 mo. There were significant decreases in bone mineral content at the spine (3.96%; 95% CI: 4.86%, 3.06%), femoral neck (2.39%; 95% CI: 3.61%, 1.17%), total hip (1.51%; 95% CI: 2.45%, 0.60%), and whole body (0.86%; 95% CI: 1.29%, 0.43%) in breast-feeding mothers but not in formula-feeding mothers or nonpregnant, nonlactating women. These changes were not related to calcium intake, breast-milk calcium concentration, vitamin D-receptor genotype, postpartum weight change, or use of the progesterone-only contraceptive pill. After adjustment for bone area, breast-milk volume and height were identified as significant predictors at the spine, such that greater decreases were associated with taller mothers (P = 0.007) and those with greater breast-milk volume (P = 0.001). This finding suggests that the marked bone mineral changes observed in breast-feeding mothers represented a physiologic response to lactation that was independent of dietary calcium supply.     

Efficiency of energy and nitrogen loss and gain in mature cows

Our objective was to quantify the energy and nitrogen balances of mature cows fed a fixed amount of forage. Six cows were assigned to each of two treatments. At time 0, control cows received 83.55+/-.52 g of chopped brome hay x (BWkg)(-.75) x d(-1). Feed intake remained fixed (9,103+/-277 g/d) over the entire 224 d of the study. At time 0 treated cows received 82.10+/-1.26 g of chopped brome hay x (BWkg)(-.75) x d(-1) (9,083+/-113 g/d). After time 0, treated cows were offered 65% of the time-0 feed intake for the first 112 d (Phase 1) and 135% of the time-0 feed intake for the last 112 d (Phase 2). Treatments were designed so that the total amount of feed received during the 224 d was the same for each treatment. Additional balance measurements were made on d 28, 56, 84, 112, 140, 168, 189, and 224. Although treatment groups differed within phases for cumulative heat production, control cows did not differ from treated cows in total heat produced during the 224-d study (P = .60). Net retained energy over the entire 224-d period did not differ between treatments (P = .43). Treated animals retained more nitrogen than did control animals (P = .008). The increased efficiency of nutrient utilization during refeeding in cows allowed to fluctuate in weight offers the potential to develop feeding strategies that improve grazed forage utilization and reduce supplemental feed.     

Analysis of mRNA for class I HLA on human gametogenic cells

The iron fortificant NaFeEDTA could have a potential negative effect on the metabolism of other minerals. We have used stable isotopes to monitor zinc and calcium metabolism in 10 women consuming a single meal of high-extraction wheat rolls (100 g flour) fortified with 5 mg Fe as either FeSO4 or NaFeEDTA. Six-day chemical balances were made simultaneously to study apparent zinc and calcium retention from the complete diet containing the differently iron-fortified breads (200 g flour; 10 mg added Fe/d). Mean 70Zn absorption from the bread meal increased from 20.9% with FeSO4 to 33.5% with NaFeEDTA (P < 0.05) whereas mean 44Ca absorption was 53.3% from both breads. When NaFeEDTA-fortified bread was consumed, there was a small but significant increase in urinary excretion of 70Zn and 44Ca. There was a similar small increase in urinary zinc excretion during the 6-d balance, although the apparent retention of zinc and calcium was not different. Thus, we found no negative overall effect of NaFeEDTA consumption on the metabolism of zinc and calcium. In contrast, the results suggest that NaFeEDTA added to low-bioavailability diets might increase zinc absorption as well as provide iron with high bioavailability.     

Evaluation of diet in a sample of Czech mothers six months after delivery

BACKGROUND: Health care of nursing mothers and their infants is an important priority of primary preventive care. The mother's diet plays an important role in this respect. The objective of the presented investigation was to assess the adequacy of the dietary intake of lactating mothers during the sixth month after delivery. METHODS AND RESULTS: Data on the education, body weight, height of the mother, dietary intake, evaluated from a three-day dietary record, were collected from 131 nursing mothers and compared with the Czech recommended dietary allowances for nursing mothers as well as with data from 265 controls, i.e. women who did no longer breastfeed their babies. From the results ensues a significantly higher calcium intake (937 mg; SD = 415, p < 0.001), vitamin B1 (1.1 mg, SD = 0.5, p < 0.001), total energy (8.7 MJ, SD = 2.6, p < 0.01), protein 75.4 g, SD = 18, p < 0.01), carbohydrates (281 g, SD = 112, p < 0.01) and riboflavin (1.3 mg, SD = 0.5, p < 0.01) in nursing women as compared with those not nursing. The nursing mothers, however, do not meet the Czech recommended dietary allowances as regards total energy, calcium, vitamin C, linoleic acid, vegetable proteins and iron. Other problematic nutrients-magnesium, zinc, folates, pyridoxine, selenium and iodine could not be assessed as they are not listed in the Czech food composition tables. In women with university education the energy and nutrient intake was in the majority more favourable than in women with elementary education. On the other hand no statistical differences were found in weight increments during the period from the beginning of gestation to the sixth month after delivery between nursing and not nursing mothers. CONCLUSIONS: The results of analysis of the dietary intake of nursing mothers indicate that the Czech recommended allowances are not met as regards energy, calcium, linoleic acid, protein and iron. Whether the intake is really inadequate or whether the recommended allowances are excessive remains an open question.