Magnesium Absorption Research Articles

Magnesium Retention in 12 to 48 Month-Old Children

Objectives: In adults, adaptation to changes in magnesium intake is largely due to changes in fractional magnesium absorption and urinary magnesium excretion. We sought to examine whether these homeostatic mechanism also occurred in young children.Methods: Children, 12–48m old were studied (n=30). They were adapted to a home diet representative of their usual magnesium intake for 7d then admitted for a stable isotope study. Children received 5mg Mg-25 intravenously, and 10mg Mg-26 orally (5mg with breakfast and 5mg with lunch). Magnesium absorption was calculated from the relative fractional excretion of the oral and intravenous isotopes in the urine samples. Endogenous fecal magnesium absorption was calculated in a subgroup from the fecal and urinary excretion of the intravenous tracer.Results: Magnesium intake (mean ± SD; 106 ± 25mg/d) was significantly greater than the Estimated Average Requirement (EAR) described by the Institute of Medicine in the US (65 mg/d, p < 0.0001). Across the range of intake studied, fractional magnesium absorption was significantly (P = 0.0383) but weakly (r2 = 0.144) related to magnesium intake. Absolute magnesium absorption (the product of fractional absorption and intake) significantly increased as intake increased (r2 = 0.566, P < 0.0001). Urinary magnesium excretion was unrelated to magnesium intake (r2 = 0.036, P = 0.31). Endogenous fecal magnesium excretion tended to increase as magnesium intake increased (r2 = 0.312, P = 0.12). Magnesium retention (absolute absorption minus urinary and fecal losses) was positive in 26 of the 30 subjects studied, and was linearly related to magnesium intake (r2 = 0.157, P = 0.0304). A magnesium intake of 52–78 mg/d would appear to be required to meet the needs for absorbed magnesium for half the children at this age range, suggesting that the current EAR is broadly appropriate.Conclusions: In young children, consuming magnesium intakes typical of the US population, fractional magnesium absorption is a major site of magnesium homeostasis, but magnesium retention increased linearly across the intake range studied. Our results support at EAR for magnesium of 55–80 mg/d and an RDA of 70–100 mg/d.

The monitoring, prevention, and treatment of milk fever and subclinical hypocalcemia in dairy cows

The periparturient cow undergoes a transition from non-lactating to lactating at calving. The animal is tremendously challenged to maintain calcium homeostasis. Those that fail can develop milk fever, a clinical disorder that is life threatening to the cow and predisposes the animal to a variety of other disorders. Guidelines for monitoring the incidence of hypocalcemia and methods for treating milk fever are reviewed. The physiological factors that cause milk fever and strategies for prevention of milk fever are discussed, focusing on the effects diet cation–anion difference can have on tissue sensitivity to parathyroid hormone. Another major risk factor for milk fever is hypomagnesemia, which is observed when animals are fed inadequate amounts of magnesium, or some factor is present in the diet that prevents adequate absorption of magnesium. Moderate hypomagnesemia impairs the ability of the cow to maintain calcium homeostasis and hypocalcemia occurs.

Recent developments in intestinal magnesium absorption

Recent identification and characterization of novel Mg transporters have clarified our understanding of intestinal magnesium absorption. The predominant Mg transporters include TRPM6 and TRPM7, members of the transient receptor potential melastatin family of cation channels. Mutations of TRPM6 result in a primary disorder termed hypomagnesemia with secondary hypocalcemia. Both TRPM6 and TRPM7 channels possess an atypical alpha-kinase domain. Recent studies have shown that TRPM7 channel activity is regulated by intracellular Mg and magnesium-nucleotides and modulated via this phosphotransferase kinase. TRPM6 channel function and intestinal magnesium absorption is altered by a variety of hormones and factors. Although it is apparent that TRPM6 and TRPM7 form heteromeric ion channels, controversy surrounds the nature of this interaction. Some studies show that TRPM6 may function on its own whereas other research concludes that TRPM7 is required for effective trafficking of TRPM6 to the plasma membrane. Finally, a number of other Mg transporters have been identified in intestinal epithelial cells but the role of these proteins is unclear. The recent developments in intestinal magnesium absorption and cellular magnesium homeostasis provide a basis for understanding magnesium deficiency disorders and provide a platform for future investigations.

Magnesium Absorption by Lactating Dairy Cows on a Grass Silage-Based Diet Supplied with Different Potassium and Magnesium Levels

The objective of the present study was to investigate the interactions of dietary K intake typical for forage-based diets on Mg balance in lactating dairy cows. Six lactating multiparous cows of the Swedish Red and White breed in midlactation were used. Two concentrations of Mg (1.9 and 4.3 g/kg of dry matter) and 3 concentrations of K (19, 28, and 37g of K/kg of dry matter) were obtained by adding appropriate amounts of MgO and KHCO3 to the diet. The experimental setup was a 6×6 Latin square design with a 2×3 factorial arrangement of treatments. Each experimental period lasted 14 d (9-d treatment adaptation period and 5-d data collection). There was no effect of Mg or K dietary supplementation on milk yield. Supplementing the ration with K did not significantly affect the Mg apparent absorption, urinary Mg excretion, or plasma Mg concentration. The Mg balance, estimated as the Mg losses in milk and urine, was positively related to Mg intake but not affected by K intake. The amount of apparently digested Mg was related to the Mg balance. The apparent digestibility ranged from 0.12 to 0.24 with no effect of mineral supplementation. There was a significant curvilinear relationship between plasma Mg and urinary Mg excretion, with a more marked increase in urinary Mg excretion at higher plasma levels of Mg.

Quantitative Prediction of Magnesium Absorption in Dairy Cows

The objective of the current study was to predict magnesium (Mg) absorption in dairy cows based on data from our own studies and those of other investigators. Balance data from 15 independent studies with 68 different rations and 323 dairy cows or cow-periods were used. In 12 studies, grass feeds were the main source of roughage and in about one-half of the studies, MgO-supplemented rations were used. Out of the 68 rations, 14 rations contained supplemental K in the form of bicarbonate, and in 2 rations additional K was incorporated mainly in form of KCl. The K content of the rations ranged from 6.9 to 75.6 g/kg of dry matter (DM; mean 29.4 g/kg of DM). In most studies (10/15), dry, nonpregnant cows were used. For lactating animals, milk yield ranged from 4 to 22 kg/d (mean yield, 15 kg/d). All studies provided quantitative information with respect to feed intake (DM intake, Mg, and K) and total Mg excretion in feces. The mean dietary Mg content was 4.5 g/kg of DM and ranged from 0.45 to 17.3 g/kg of DM. On average, Mg absorption (% of intake) was 26.2% and ranged from 9.9 to 73.7%. The variation in Mg absorption was at least partly explained by the variation in dietary K concentrations. Magnesium absorption (% of intake) was significantly decreased by 0.31 percentage units/g of K in the DM. To counteract the depressant effect of dietary K on Mg absorption, Mg intake must be increased by 4 g/d when the dietary K concentration increases by 10 g/kg of DM so that the amount of absorbed Mg is maintained.

Magnesium Metabolism

Magnesium is the second most common intracellular divalent cation. Magnesium balance in the body is controlled by a dynamic interplay among intestinal absorption, exchange with bone, and renal excretion. Intestinal magnesium absorption proceeds in both a passive paracellular and an active transcellular manner. Regulation of serum magnesium concentrations is achieved mainly by control of renal magnesium reabsorption. Only 20% of filtered magnesium is reabsorbed in the proximal tubule, whereas 60% is reclaimed in the cortical thick ascending limb (TAL) and another 5-10% in the distal convoluted tubule (DCT). The passive paracellular transport of magnesium in the TAL is closely related with the mutations in claudin-16/paracellin-1 and is responsible for familial hypomagnesemia with hypercalciuria and nephrocalcinosis. The active transcellular transport of magnesium in the DCT was similarly enhanced by the realization that defects in transient receptor potential melastatin 6 (TRPM6) cause hypomagnesemia with secondary hypocalcemia. This channel regulates the apical entry of magnesium into epithelia and alters whole-body magnesium homeostasis by controlling urinary excretion. TRPM6 is regulated at the transcriptional level by acid-base status, 17β-estradiol, and both FK506 and cyclosporine. The molecular identity of the protein responsible for the basolateral exit of magnesium from the epithelial cell remains unidentified.

Inulin-Type Fructans: Functional Food Ingredients

A food (ingredient) is regarded as functional if it is satisfactorily demonstrated to affect beneficially 1 or more target functions in the body beyond adequate nutritional effects. The term inulin-type fructans covers all β(2←1) linear fructans including native inulin (DP 2–60, DPav = 12), oligofructose (DP 2–8, DPav = 4), and inulin HP (DP 10–60, DPav = 25) as well as Synergy 1, a specific combination of oligofructose and inulin HP. Inulin-type fructans resist digestion and function as dietary fiber improving bowel habits. But, unlike most dietary fibers, their colonic fermentation is selective, thus causing significant changes in the composition of the gut microflora with increased and reduced numbers of potentially health-promoting bacteria and potentially harmful species, respectively. Both oligofructose and inulin act in this way and thus are prebiotic: they also induce changes in the colonic epithelium and in miscellaneous colonic functions. In particular, the claim “inulin-type fructans enhance calcium and magnesium absorption” is scientifically substantiated, and the most active product is oligofructose-enriched inulin (Synergy 1). A series of studies furthermore demonstrate that inulin-type fructans modulate the secretion of gastrointestinal peptides involved in appetite regulation as well as lipid metabolism. Moreover, a large number of animal studies and preliminary human data show that inulin-type fructans reduce the risk of colon carcinogenesis and improve the management of inflammatory bowel diseases. Inulin-type fructans are thus functional food ingredients that are eligible for enhanced function claims, but, as more human data become available, risk reduction claims will become scientifically substantiated.

Digesta characteristics in relation to nutrient digestibility and mineral absorption in Nile tilapia (Oreochromis niloticus L.) fed cereal grains of increasing viscosity

Soluble non-starch polysaccharides (NSP) present in cereal grains may affect performance of Nile tilapia through changes in digesta characteristics. The objective of this study was to investigate whether dietary cereal grains of increasing viscosity induce changes in digesta viscosity, dry matter and volatile fatty acids (VFA) and if these changes explain differences in nutrient digestibility and mineral absorption. Four experimental diets were formulated by adding 40% grains to a basal diet to obtain a range of dietary viscosities, increasing in the order of maize, barley, wheat and rye. The diets were assigned to 16 tanks with 40 fish (mean weight 70 g) each. Digesta viscosity increased with increasing grain viscosity (P<0.001), whereas digesta dry matter decreased with increasing grain viscosity (P<0.05). No significant differences were found among diets in total concentration and type of VFA. Nutrient digestibility was not significantly correlated with digesta viscosity. Of all nutrients, only starch digestibility was significantly negatively correlated with digesta dry matter in the middle intestine (r=−0.57; P=0.03). Absorption of sodium was significantly negatively correlated with digesta viscosity in all intestinal segments (r=−0.76 to −0.82; P<0.001) and positively correlated with digesta dry matter in all intestinal segments (r=+0.60 to +0.67; P<0.05), except for the proximal intestine (P=0.18). Of the other minerals, potassium and magnesium absorption were positively correlated with digesta dry matter in the distal (r=+0.56; P=0.03) and proximal (r=+0.54; P=0.04) intestine, respectively. Phosphorus absorption was significantly negatively correlated with dry matter in the stomach (r=−0.55; P=0.03), middle (r=−0.58; P=0.02) and distal (r=−0.54; P=0.04) intestine. In conclusion, viscous cereal grains induce increases in digesta viscosity and decreases in digesta dry matter in Nile tilapia. These changes do not explain differences in nutrient digestibility among diets, but seem more related to differences in mineral absorption. The strong negative correlations between digesta viscosity and sodium absorption suggest negative effects of dietary viscous grains on intestinal water balance.

The relation of magnesium and calcium intakes and a genetic polymorphism in the magnesium transporter to colorectal neoplasia risk

Background: Mean magnesium intake in the US population does not differ from that in East Asian populations with traditionally low risks of colorectal cancer and other chronic diseases, but the ratio of calcium to magnesium (Ca:Mg) intake is much higher in the US population. Transient receptor potential melastatin 7 (TRPM7) is a newly found gene essential to magnesium absorption and homeostasis.Objective: We aimed to test whether the association of colorectal polyps with intake of calcium, magnesium, or both and Thr1482Ile polymorphism in the TRPM7 gene is modified by the Ca:Mg intake.Design: Included in the study were a total of 688 adenoma cases, 210 hyperplastic polyp cases, and 1306 polyp-free controls from the Tennessee Colorectal Polyp Study.Results: We found that total magnesium consumption was linked to a significantly lower risk of colorectal adenoma, particularly in those subjects with a low Ca:Mg intake. An inverse association trend was found for hyperplastic polyps. We also found that the common Thr1482Ile polymorphism was associated with an elevated risk of both adenomatous and hyperplastic polyps. Moreover, this polymorphism significantly interacted with the Ca:Mg intake in relation to both adenomatous and hyperplastic polyps. The subjects who carried ≥1 1482Ile allele and who consumed diets with a high Ca:Mg intake were at a higher risk of adenoma (odds ratio: 1.60; 95% CI: 1.12, 2.29) and hyperplastic polyps (odds ratio: 1.85; 95% CI: 1.09, 3.14) than were the subjects who did not carry the polymorphism.Conclusion: These findings, if confirmed, may provide a new avenue for the personalized prevention of magnesium deficiency and, thus, colorectal cancer.

MODELING MACRONUTRIENT ABSORPTION OF HYDROPONICALLY-GROWN CUT FLOWER ROSES

Regulations increasingly limit the water run-off allowed from agricultural facilities. A better understanding of appropriate irrigation and fertilization regimes are needed to comply with these regulations. The objectives of this project were to determine how macronutrient absorption by roses varies in relationship to growth of new flower stems and test whether an existing mathematical model is suitable for describing nitrogen and potassium uptake across a crop cycle. Absorption of ammonium (NH4 + ), nitrate (NO3 - ), potassium (K + ), calcium (Ca 2+ ), and magnesium (Mg 2+ ) by rose plants (Rosa × hybrida ‘Kardinal’) were measured during three crop cycles. Following a harvest, the rate of total nitrogen (N) uptake decreased to 0.15 mmol d -1 g -1 harvested dry weight (HDW) where it remained for the first five days, decreased during days 8-10, and then increased in synchrony with flower stem elongation. K + uptake rates gradually declined for the first 12 days following a harvest cycle, then increased in synchrony with stem elongation to maximum uptake rates of 0.05 to 0.09 mmol d -1 g -1 HDW as stems reached maturity. Prior to harvest, the rate of Ca 2+ uptake decreased and remained low until day 7 of the new cycle (appearance of new shoots), then increased until just prior to stem maturity. Mg 2+ uptake rate increased in synchrony with stem elongation and then decreased just prior to harvest. Simulations of the N/K + model accurately predicted the increase in N and K + uptake rates beginning around day 10-12 and proceeding until harvest as well as the drop in N and K + uptake occurring at harvest. The simulation does not predict the somewhat sustained uptake rates for the first 7-10 days following harvest and the decline in uptake during early stem elongation. The most likely reason for the discrepancy is that the model does not yet have mechanisms for handling redistribution of these nutrients from perennial tissues to new growing shoots or account for changes in root growth across a crop cycle.

The Michigan/MIKE Fiber System Survey of Stellar Radial Velocities in Dwarf Spheroidal Galaxies: Acquisition and Reduction of Data

We introduce a stellar velocity survey of dwarf spheroidal galaxies, undertaken using the Michigan/MIKE Fiber System (MMFS) at the Magellan/Clay 6.5 m telescope at Las Campanas Observatory. As of 2006 November we have used MMFS to collect 6415 high-resolution (R= 20000-25000) spectra from 5180 stars in four dwarf spheroidal galaxies: Carina, Fornax, Sculptor and Sextans. Spectra sample the range 5140-5180 Angstroms, which includes the prominent magnesium triplet absorption feature. We measure radial velocity (RV) to a median precision of 2.0 km/s for stars as faint as V ~ 20.5. From the spectra we also are able to measure the strength of iron and magnesium absorption features using spectral indices that correlate with effective temperature, surface gravity and chemical abundance. Measurement of line strength allows us to identify interloping foreground stars independently of velocity, and to examine the metallicity distribution among dSph members. Here we present detailed descriptions of MMFS, our target selection and spectroscopic observations, the data reduction procedure, and error analysis. We compare our RV results to previously published measurements for individual stars. In some cases we find evidence for a mild, velocity-dependent offset between the RVs we measure using the magnesium triplet and previously published RV measurements derived from the infrared calcium triplet. In companion papers we will present the complete data sets and kinematic analyses of these new observations.

Egg Yolk Protein and Egg Yolk Phosvitin Inhibit Calcium, Magnesium, and Iron Absorptions in Rats

Egg yolk decreases the absorption of iron. The effects of egg yolk protein and egg yolk phosvitin on the absorption of calcium, magnesium, and iron were investigated by in vivo studies. Male Wistar rats were fed purified diets containing casein, soy protein, or egg yolk protein for 14 d. The apparent absorptions of calcium, magnesium, and iron in the rats fed the yolk protein-based diet were lower than those in rats fed the casein- and soy protein-based diets. The apparent phosphorus absorption and the apparent protein digestibility in the yolk protein group were lower than those in the casein and soy protein groups. In the feces of the yolk protein group, serine comprised more than 30% of the amino acids. The addition of egg yolk phosvitin to the casein diets at levels of 1% and 2% (w/w) produced effects on calcium and magnesium absorptions similar to those produced by the diet containing yolk protein. The tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern suggested that phosphopeptide fragments having molecular masses of 28, 22, and 15 kDa were evident in the contents of the small intestine of the rats fed phosvitin diets. These results indicate that yolk protein, when compared with casein and soy protein, decreases calcium and magnesium absorption via the resistance of phosvitin to proteolytic action.

Effects of Local Nitrogen Supply on Water Uptake of Bean Plants in a Split Root System

AbstractTo study the effects of local nitrogen supply on water and nutrient absorption, French bean (Phaseolus vulgaris L.) plants were grown in a split root system. Five treatments supplied with different nitrogen forms were compared: homogeneous nitrate (NN) and homogenous ammonium (AA) supply, spatially separated supply of nitrate and ammonium (NA), half of the root system supplied with N‐free nutrient solution, the other half with either nitrate (N0) or ammonium (A0). The results showed that 10 d after onset of treatments, root dry matter (DM) in the nitrate‐supplied vessels treated with NA was more than two times higher than that in the ammonium‐supplied vessels. Water uptake from the nitrate‐supplied vessels treated with NA was 281% higher than under ammonium supply. In treatments N0 and A0, the local supply of N resulted in clearly higher root DM, and water uptake from the nitrate‐supplied vessels was 82% higher than in the ‐N vessels. However, in A0 plants, water uptake from the ‐N nutrient solution was 129% higher than from the ammonium‐supplied vessels. This indicates a compensatory effect, which resulted in almost identical rates of total water uptake of treatments AA and A0, which had comparable shoot DM and leaf area. Ammonium supply reduced potassium and magnesium absorption. Water uptake was positively correlated with N, Mg and K uptake.

Effects of probiotic, prebiotic and synbiotic follow‐up infant formulas on large intestine morphology and bone mineralisation in rats

AbstractThe effects of powder functional follow‐up infant formulas on the morphology of the large intestine and the bone mineral content in rats were investigated. Infant formulas were supplemented with probiotics (Bifidobacterium bifidum and Bifidobacterium longum), prebiotics (galacto‐oligosaccharides (4′‐GOS) at 12, 50 and 100 g kg−1) or synbiotics (bifidobacteria and 4′‐GOS) and administered to seven groups of weanling rats over 30 days. After sacrificing the animals, the caecum and colon were removed and the luminal content pH and the crypt depth and cell density within the epithelial layer were measured. Results showed that groups fed synbiotic diets had significantly (P &lt; 0.05) lower caecal and colonic content pH values compared with the control group. However, no test diet significantly modified the crypt depth or cell density in the caecum. In contrast, all seven test diets significantly increased (P &lt; 0.05) the crypt depth in both the proximal and distal portions of the colon. There was a high correlation (Pearson correlation coefficient 0.870) between caecal and colonic content pH values. On the other hand, colonic content pH was negatively correlated with crypt depth in both the proximal and distal colon and with cell density in the distal colon. The authors previously reported increases in calcium, magnesium and phosphorus absorption using the same infant formulas. In the present study it was concluded that the increase in calcium absorption took place in the distal colon whereas magnesium absorption increased in both the proximal and distal colon, and their contents (especially that of calcium) increased in both the femur and tibia. Copyright © 2007 Society of Chemical Industry

Effects of oligofructose-enriched inulin on intestinal absorption of calcium and magnesium and bone turnover markers in postmenopausal women.

Deficiency of oestrogen at menopause decreases intestinal Ca absorption, contributing to a negative Ca balance and bone loss. Mg deficiency has also been associated with bone loss. The purpose of the present investigation was to test the hypothesis that treatment with a spray-dried mixture of chicory oligofructose and long-chain inulin (Synergy1; SYN1) would increase the absorption of both Ca and Mg and alter markers of bone turnover. Fifteen postmenopausal women (72.2 (SD 6.4) years) were treated with SYN1 or placebo for 6 weeks using a double-blind, placebo-controlled, cross-over design. Fractional Ca and Mg absorption were measured using dual-tracer stable isotopes before and after treatment. Bone turnover markers were measured at baseline, 3 and 6 weeks. Fractional absorption of Ca and Mg increased following SYN1 compared with placebo (P < 0.05). Bone resorption (by urinary deoxypyridinoline cross-links) was greater than baseline at 6 weeks of active treatment (P < 0.05). Bone formation (by serum osteocalcin) showed an upward trend at 3 weeks and an increase following 6 weeks of SYN1 (P < 0.05). Closer examination revealed a variation in response, with two-thirds of the subjects showing increased absorption with SYN1. Post hoc analyses demonstrated that positive responders had significantly lower lumbar spine bone mineral density than non-responders (dual X-ray absorptiometry 0.887 +/- 0.102 v. 1.104 +/- 0.121 g/cm2; P < 0.01), and changes in bone turnover markers occurred only in responders. These results suggest that 6 weeks of SYN1 can improve mineral absorption and impact markers of bone turnover in postmenopausal women. Further research is needed to determine why a greater response was found in women with lower initial spine bone mineral density.

Uremia-related vascular calcification: More than apatite deposition

In the present study, we characterized and compared the mineral phase deposited in the aortic wall of two different frequently used chronic renal failure rat models of vascular calcification. Vascular calcification was induced in rats by either a 4-week adenine treatment followed by a 10-week high-phosphate diet or 5/6 nephrectomy followed by 6 weeks of 0.25 microg/kg/day calcitriol treatment and a high-phosphate diet. Multi-element mapping for calcium and phosphate together with mineral identification was performed on several regions of aortic sections by means of synchrotron X-ray-mu-fluorescence and diffraction. Bulk calcium and magnesium content of the aorta was assessed using flame atomic absorption spectrometry. Based on the diffraction data the Von Kossa-positive precipitate in the aortic regions (N=38) could be classified into three groups: (1) amorphous precipitate (absence of any diffraction peak pattern, N=12); (2) apatite (N=16); (3) a combination of apatite and magnesium-containing whitlockite (N=10). The occurrence of these precipitates differed significantly between the two models. Furthermore, the combination of apatite and whitlockite was exclusively found in the calcitriol-treated animals. These data indicate that in adenine/phosphate-induced uremia-related vascular calcification, apatite is the main component of the mineral phase. The presence of magnesium-containing whitlockite found in addition to apatite in the vitamin D-treated rats, has to be seen in view of the well-known vitamin D-stimulated gastrointestinal absorption of magnesium.

Are Plasma Citrulline and Glutamine Biomarkers of Intestinal Absorptive Function in Patients With Short Bowel Syndrome?

Sensitive biomarkers for intestinal absorptive function would be clinically useful in short bowel syndrome (SBS). Citrulline (Cit) is a product of the metabolism of glutamine (Gln) and derived amino acids by enterocytes. Cit is produced almost exclusively by the gut, which is also a major site of Gln metabolism. The goals of this study were to examine whether plasma Cit and Gln concentrations are biomarkers of residual small intestinal length and nutrient absorptive functions in adult SBS patients followed prospectively. We studied 24 stable adults with severe SBS receiving chronic parenteral nutrition (PN) in a double-blind, randomized trial of individualized dietary modification +/- recombinant human growth hormone (GH). During a baseline week, intestinal absorption studies (% absorption of fluid, kcal, nitrogen, fat, carbohydrate, sodium, phosphorus, and magnesium) were performed and concomitant plasma Cit and Gln concentrations determined. Individualized dietary modification and treatment with subcutaneous injection of placebo (n = 9) or GH (0.1 mg/kg daily x 21 days, then 3 times/week; n = 15) were then begun. PN weaning was initiated after week 4 and continued as tolerated for 24 weeks. Repeat plasma amino acid determination and nutrient absorption studies were performed at weeks 4 and 12. Residual small bowel length at baseline was positively correlated with baseline plasma Cit (r = 0.467; p = .028). However, no significant correlations between absolute Cit or Gln concentrations and the percent absorption of nutrient substrates at any time point were observed. Similarly, no correlation between the change in Cit or GLN concentration and the change in % nutrient absorption was observed (baseline vs weeks 4 and 12, respectively). By weeks 12 and 24, 7 and 13 subjects were weaned completely from PN, respectively. However, baseline plasma Cit or Gln did not predict PN weaning at these time points. We concluded that plasma Cit (but not Gln) concentrations appeared to be an indicator of small intestinal length in adult SBS. However, neither plasma Cit nor Gln was a biomarker for intestinal absorptive function in this cohort of patients with SBS.

Impact of sewage sludge and composts prepared from sewage sludge on the content and uptake of macronutrients by straw of miscanthus sacchariflorus

Impact of sewage sludge and composts prepared from sewage sludge on the content and uptake of macronutrients by straw of miscanthus sacchariflorus The pot experiment was set up under the conditions of the hall of vegetation in 2002. The municipal sewage sludge and composts produced with the GWDA method in 2001 based on municipal sewage sludge with the 30% addition of structuring materials, in conversion to the dry matter, were used in the experiment. The pot experiment was set up with the split-split-plot method in three repetitions. The objects of the first factor were the doses of sewage sludge and composts (1 dose = 13 g, 2 dose = 26 g, 3 dose = 39 g, 4 dose = 52 g of dry matter in relation to the soil weight in the pot), the objects of the second factor were the types of organic fertilization (sewage sludge, 0,5-year compost prepared from sewage sludge, 1,5-year compost prepared from sewage sludge), objects of the third factor were the variants with and without nitrogen and potassium fertilization in the rates of 0.27 g N and 0.26 g K per pot. The experiment was conducted in Kick-Brauckmann's pots of 9 dm3 capacity in which 8 kg of soil were placed. The test plant cultivated in the experiment was Miscanthus sachariflorus. Seedlings of Miscanthus were planted in the first year of the experiment. The obtained results show that the content of macronutrients: nitrogen, phosphorus, potassium in straw of Miscanthus sachariflorus was not dependent on the type of organic fertilizers used in the experiment. However, supplemental nitrogen-potassium fertilization significantly increases the content of potassium in the test plant in all three years of research and nitrogen in the second year. The conducted research shows that the uptake of macronutrients depended on the dry matter yield quantity and the content of a given element in the yield. Within three years the straw of Miscanthus sacchariflorus took up the most of potassium - 11.63 g from the pot and the least of magnesium 1.20 g from the pot. The amount of the absorption of nitrogen, phosphorus and magnesium by the biomass of Miscanthus sacchariflorus from the pot on the objects fertilized with organic fertilizers was the highest in the second year of the research, which was a result of mineralization of the applied fertilizers.

Effect of Lactulose on Calcium and Magnesium Absorption: A Study Using Stable Isotopes in Adult Men

To evaluate the effect of lactulose on calcium (Ca) and magnesium (Mg) absorption, we performed a clinical trial with a double-blind, randomized, crossover design in 24 healthy adult male volunteers. The absorptions of Ca and Mg were evaluated by a single-labeling method using stable isotopes. The test foods, containing lactulose at a dose of 0 g (placebo), 2 g (low-dose), or 4 g (high-dose) together with 300 mg of Ca containing 20 mg of 44Ca, and 150 mg of Mg containing 28 mg of 25Mg, were administered orally. Urine samples were collected for 8 h after the ingestion of the test food. The ratios of stable isotopes in urine (44Ca/40Ca and 25Mg/24Mg) were measured by ICP-MS (inductively coupled plasma-mass spectrometry). The urinary stable-isotopes ratios (44Ca/40Ca and 25Mg/24Mg) increased with lactulose dosage. Significant differences were observed in the Ca ratio between placebo and high-dose lactulose (p<0.01), and in the Mg ratio between placebo and low-dose lactulose and between placebo and high-dose lactulose (p<0.01). Lactulose ingestion did not change the levels of bone-resorption markers (type I collagen cross-linked N-telopeptide and deoxypyridinoline) in urine. The test foods did not cause any side effects. This study demonstrates that lactulose enhances the absorptions of Ca and Mg in adult men.

Prevention of osteoporosis by foods and dietary supplements. The effect of fructooligosaccharides (FOS) on the calcium absorption and bone

Fructooligosaccharides (FOS) are well known as prebiotics which improve intestinal microflaura. FOS also have increasing effect on the intestinal absorption of calcium (Ca), magnesium (Mg) and iron. These effects were inspected by many animal experiments and then by human studies. Especially, FOS clearly prevent the decrease of bone mineral density by gastrectomy in rats. In this report, we mainly explain the preventive effect of FOS on the bone of gastrectomized rats and introduce relationship between another food ingredient or exercise.