Repletion Diets Research Articles

Effects of short-term mild calorie restriction diet and renutrition with ruminant milks on leptin levels and other metabolic parameters in mice

Objective The adaptation of an organism to a calorie-restricted diet is characterized by metabolic, endocrine, and immunologic changes. The objective of this study was to determine, in a mouse model, the changes in serum leptin levels in response to short-term mild calorie-restricted and renutrition diets using different ruminant milks. Methods Weaned Swiss albino mice were fed with a mild calorie-restricted diet for 12 d, after which they were renourished with cow, goat, sheep, or buffalo milk for 7 d. Body, thymus, and spleen weights and biochemical, hematologic, and endocrine parameters were evaluated. Results The mild calorie restriction did not significantly modify insulin and leptin levels. The renutrition diets increased insulin levels, being significant ( P < 0.05) only when buffalo and sheep milks were used. Leptin concentrations increased in the control ad libitum (AD) group during the assayed period. After the administration of cow and goat milks, lower leptin levels were observed compared with the control AD group. All repletion diets significantly increased body, thymus, and spleen weights; however, spleen weight did not reach the values observed in the control AD group. Serum glucose and triacylglycerol levels increased after feeding with the renutrition diets. However, serum cholesterol did not increase after the renutrition period. We observed a significant decrease ( P < 0.05) in the leukocyte counts in calorie-restricted mice in comparison with AD mice; after the renutrition period, the leukocyte count did not reach the values for the AD mice. Conclusion This study suggests that a short-term change in diet with a relatively low body weight loss does not significantly affect leptin concentrations in our mouse model. However, the assayed milks could be effectively used as alternative milk sources for weight gain and for the improvement of other metabolic parameters.

Lactobacillus casei addition to a repletion diet-induced early normalisation of cytokine profils during a pneumococcal infection in malnourished mice

This work studied the influence of Lactobacillus casei on cytokine production during repletion of malnourished mice in the face of an infectious challenge. In addition, the number and function of cells involved in the immune response against a respiratory infection was evaluated. Weaned mice were malnourished after consuming a protein-free diet (PFD) for 21 days. Malnourished mice were fed a balanced conventional diet (BCD) for 7 days or BCD for 7 days with L. casei supplementation on day 6 and day 7 (BCD+Lc). The malnourished control group (MNC) received PFD while the well-nourished control (WNC) mice consumed BCD. Mice were challenged intranasally with Streptococcus pneumoniae at the end of each dietary treatment. Malnutrition impaired the levels of serum tumor necrosis factor (TNF)-α and interleukin (IL)-1β, IL-4, IL-6 and IL-10. In addition, neutrophil number and activity, lymphocyte maturation and bone marrow CD4+, CD8+ and CD19+ cells number, were also impaired in the MNC group. Repletion with BCD induced a slight improvement in some of the parameters studied. However, when L. casei was added to the BCD, a normalisation of TNF-α, IL-1β and IL-6 values after infection and an increase in the levels of IL-10 and IL-4 compared to the WNC group was observed. Moreover, BCD+Lc induced a significant improvement in blood and bone marrow cells. Consequently, the use of L. casei as a supplement in a repletion diet was associated with a pattern of inflammatory and anti-inflammatory cytokines that led to an increased number and functionality of the cells that participate in the immune response against a pneumococcal infection.

Effects of CLA at different dietary fat levels on the nutritional status of rats during protein repletion

Objective Protein depletion is associated with decreased body weight gain, low nitrogen balance, intrahepatic lipid accumulation, and hypoalbuminemia. Because conjugated linoleic acid (CLA) can increase lean body mass, enhance feed efficiency, and modulate lipid metabolism, this study investigated the effects of CLA at two levels of dietary fat on energy efficiency, nitrogen retention, and plasmatic and hepatic lipid levels in rats during dietary protein repletion. Methods The animals were subjected to a moderate protein restriction for 14 d. After that, they were fed a protein repletion diet for 30 d, supplemented or not with CLA at recommended and high-fat levels. Energy efficiency, nitrogen balance, and nutritional parameters in serum and tissues were evaluated. Results Protein repletion improved most of the nutritional parameters evaluated independently of CLA supplementation at both fat levels. At recommended fat levels, CLA did not have any effect. At high-fat levels, energy efficiency increased more than 20% by fat accumulation in carcasses and epididymal pads, serum cholesterol increased (two-fold), and liver triacylglycerol accumulation remained elevated. However, at high-fat levels, CLA prevented lipid accumulation in liver and adipose tissue. Conclusion Protein repletion improved the nutritional status of protein-restricted rats with minor effects of CLA at both dietary fat levels. However, when high-fat diets were given, CLA-enriched oil showed preventive effects on liver and adipose tissue lipid accumulation and no deleterious effects were observed. Because there are no studies dealing with CLA effects on protein repletion, this experimental model could improve nutritional interventions to overcome the protein-deficit stage.

Effect of dietary phosphorus and its interaction with genetic background on global gene expression in porcine muscle

Environmental concerns and costs associated with dietary phosphorus (P) supplementation have lead to attempts to minimize the amount of P added to swine diets. In addition to its requirement for bone growth, dietary P is also necessary for muscular growth. To examine the effects of genetic background and dietary P on global gene expression in the muscle of young pigs, we utilized muscle tissue from 36 gilts sired from two different sire lines. These animals were fed either a P adequate, P deficient or P repletion diets for 14 days and showed differences in growth performance and bone integrity in response to the interaction of genetic background and dietary P. Total RNA from the loin muscle of these animals was obtained for microarray analysis. Significant differences (p<0.01) in gene expression were seen based on the effect of sire line (339 genes), dietary P (18 genes) and the interaction between sire line and dietary P (31 genes). The microarray data were validated by semi-quantitative real-time PCR. These results support our hypothesis that genetic background and dietary P treatment can affect the homeorhetic control of P metabolism in pigs. Genes identified as differentially expressed in this study may be excellent candidate genes for additional work to elucidate genotype specific P requirements as well as to identify a genetic background that can maintain superior growth in a more environmentally friendly manner.

Excretion of the Urinary 5C- and 7C-Aglycone Metabolites of Vitamin K by Young Adults Responds to Changes in Dietary Phylloquinone and Dihydrophylloquinone Intakes

The physiological function and putative health roles of vitamin K-dependent proteins now extend beyond their classical role in hemostasis and include bone mineralization, arterial calcification, apoptosis, phagocytosis, growth control, chemotaxis, and signal transduction. Current assessments of vitamin K status do not reflect the variety of molecular forms of vitamin K. We assessed whether urinary excretion of 2-methyl-3-(5´-carboxy-3´-methyl-2´-pentenyl)-1,4-naphthoquinone (7C-aglycone) and 2-methyl-3-(3´-3´-carboxymethylpropyl)-1,4-naphthoquinone (5C-aglycone), vitamin K metabolites common to both phylloquinone and the menaquinone series, reflect dietary vitamin K intake. In a randomized crossover study, 9 adults resided in a metabolic unit for two 30-d periods separated by a free-living period of ≥4 wk. During each residency, subjects consumed 3 sequential diets: a control diet (93 μg phylloquinone/d) for 5 d, a phylloquinone-restricted diet (11 μg/d) for 15 d, followed by a randomly assigned repletion diet for 10 d with either phylloquinone (206 μg/d) or dihydrophylloquinone (240 μg/d). During the second residency, the alternative repletion diet was assigned. Urinary excretion of the 5C- and 7C-aglycones was measured in sequential 24-h collections. The 5C-aglycone accounted for ∼75% of total excretion and declined in response to phylloquinone restriction (P = 0.001) to ∼30% of that during the control diet period. Repletion with phylloquinone and dihydrophylloquinone doubled the excretion rate of the major 5C-aglycone by 24 h (P < 0.001), and tripled excretion by 4 d. There was a linear relationship between the logarithm of total urinary excretion and dietary vitamin K intake (r = 0.699, P < 0.001). We conclude that the urinary excretion of vitamin K metabolites reflects dietary phylloquinone intake and offers the first candidate marker of global vitamin K status.

Genetic Background Alters Gene Expression in Small Intestine, Liver and Bone Marrow in Response to Dietary Phosphorus in Young Pigs

Phosphorus (P) is essential to bone growth, however, little research focused on the genetic mechanisms controlling P utilization. Understanding the interactions between genetics and dietary P that optimize bone integrity could provide novel interventions for osteoporosis. We utilized 36 female pigs from 2 genetic lines known to differ in bone structure (lighter-boned or heavier-boned) to examine the interactions between genetic background and dietary P. Pigs were fed a P adequate, P deficient or P repletion diet for 2 wk. At the completion of the trial, RNA was isolated from liver, small intestine and bone marrow for quantification of gene expression by real-time PCR. Gene expression data was analyzed with sire line, diet and their interaction considered as fixed effects. Differential expression (P < .1) of parathyroid hormone receptor (PTHR), estrogen receptor alpha (ESR1), insulin-like growth factor 1 (IGF1), IGF binding proteins 3 and 5 (IGFBP3 and IGFBP5) message was seen in the small intestine. In liver tissue, the expression of ESR1, vitamin D receptor (VDR), PTHR, growth hormone receptor (GHR), IGFBP3, IGFBP5, calcitonin receptor and oxytocin receptor was affected (P < .1) by either dietary P or the interaction between dietary P and genetic background. Differential expression (P < .1) of peroxisome proliferator activated receptor gamma 2 (pPARG2) and ESR1 message was also seen in the bone marrow due to the interactions of diet and genetic background. Understanding these differences could lead to novel treatments for osteoporosis and aid in the development of tests for identifying those at risk for this disease. Acknowledgements This research was funded in part by Sygen International.

Lactobacillus casei Improves Resistance to Pneumococcal Respiratory Infection in Malnourished Mice

We studied the effect of Lactobacillus casei CRL 431 used as a supplement in a repletion diet on the resistance to Streptococcus pneumoniae respiratory infection in malnourished mice. Weaned mice were malnourished after they consumed a protein-free diet (PFD) for 21 d. Malnourished mice were fed a balanced conventional diet (BCD) with or without supplemental L. casei for 7, 14, or 21 consecutive days, or BCD for 7 d with L. casei supplementation on d 6 and 7 (7dBCD+2dLc). The malnourished control (MNC) group was fed only the PFD, whereas well-nourished control (WNC) mice consumed the BCD ad libitum. Mice were challenged with S. pneumoniae at the end of each dietary treatment. Lung colonization and bacteremia were significantly greater in MNC than in WNC. Normalization of the immune response occurred in malnourished mice fed the BCD for 21 d. L. casei supplementation reduced the time required for a normal response from 21 to 7 d. Mice administered the 7dBCD+2dLc repletion treatment had a more effective pathogen clearance from blood and significantly lower lung damage than MNC. This treatment improved both the number of leukocytes and neutrophils in blood and bronchoalveolar lavages (BAL) and the bactericidal function of phagocytic cells to levels that did not differ from those of WNC. In the 7dBCD+2dLc mice, antipneumococcal IgA in BAL was higher than in WNC, whereas antipneumococcal IgG in serum and BAL did not differ. This study suggests that the addition of L. casei to the repletion diet has a beneficial effect because it accelerates the recovery of the innate immune response and improves the specific immune mechanisms against an S. pneumoniae respiratory infection in malnourished mice.

Bioavailability of Elemental Iron Powders to Rats Is Less than Bakery-Grade Ferrous Sulfate and Predicted by Iron Solubility and Particle Surface Area

Foods are fortified with elemental forms of iron to reduce iron deficiency. However, the nutritional efficacy of current, commercially produced elemental iron powders has not been verified. We determined the bioavailability of six commercial elemental iron powders and examined how physicochemistry influences bioavailability. Relative biological value (RBV) of the iron powders was determined using a hemoglobin repletion/slope ratio method, treating iron-deficient rats with repletion diets fortified with graded quantities of iron powders, bakery-grade ferrous sulfate or no added iron. Iron powders were assessed physicochemically by measuring iron solubility in hydrochloric acid at pH 1.0 and 1.7, surface area by nitrogen gas adsorption and surface microstructure by electron microscopy. Bioavailability from the iron powders, based on absolute iron intake, was significantly less than from FeSO4 (100%; P < 0.05) with the following rank order: Carbonyl (64%; Ferronyl, U.S.) > Electrolytic (54%; A-131, U.S.) > Electrolytic (46%; Electrolytic Iron, India) > H-Reduced (42%; AC-325, U.S.) > Reduced (24%; ATOMET 95SP, Canada) > CO-Reduced (21%; RSI-325, Sweden). Solubility testing of the iron powders resulted in different relative rankings and better RBV predictability with increasing time at pH 1.7 (R2 = 0.65 at 150 min). The prediction was improved with less time and lower pH (R2 = 0.82, pH 1.0 at 30 min). Surface area, ranging from 90 to 370 m2/kg, was also highly predictive of RBV (R2 = 0.80). Bioavailability of iron powders is less than bakery-grade ferrous sulfate and varies up to three times among different commercial forms. Solubility at pH 1.0 and surface area were predictive of iron bioavailability in rats.

Folate Derived from Cecal Bacterial Fermentation Does Not Increase Liver Folate Stores in 28-d Folate-Depleted Male Sprague-Dawley Rats

This study assessed the ability of rats to absorb and store the folate synthesized by cecal bacteria. Male weanling Sprague-Dawley rats were folate depleted by feeding a low folacin AIN93G formulated basal diet for 28 d; they were then fed repletion diets containing folate (0.25-1.0 mg/kg diet), dietary fiber (DF; wheat bran, oat bran, ground corn, wheat germ) or undigested and fermented dietary material (UFDM; polydextrose, inulin) in the presence and absence of an antibiotic (succinylsulfathiazole). Fermentation was stimulated by DF and UFDM and reduced by the antibiotic. In the absence of succinylsulfathiazole, the increase in liver folate (during the repletion phase) was proportional only to the folate content of the diet and did not vary with added DF or UFDM. Adding succinylsulfathiazole lowered total folate excretion from 13.8 +/- 8.2 to 4.8 +/- 2.9 nmol/d (pooled diets, P < 0.00001) in agreement with its role in inhibiting bacterial folate synthesis. In addition, succinylsulfathiazole lowered liver folate in rats fed control and test diets approximately equally with a mean decrease from 11.6 +/- 2.5 to 7.5 +/- 2.5 nmol/g wet liver (pooled diets, P < 0.00001), suggesting that the antibiotic also affected rat folate absorption and/or metabolism. Increased bacterial fermentation and excretion as well as increased bacterial folate production in the presence of added DF and UFDM were demonstrated by increased volatile fatty acid content in cecal and fecal samples (P < 0.000001) and increased diaminopimelic acid, muramic acid and folate in feces (P < 0.00001). The magnitude of these changes depended on the type of DF and UFDM. These results show that bacterially synthesized folate is not substantially absorbed and stored in the liver of Sprague-Dawley male rats.

The effects of protein repletion at varied levels on the growth and nutritional status of protein restricted rats

Effects of protein restriction and subsequent repletion were studied for 34 days using 43 male weanling Sprague-Dawley rats. Thirty-three rats were fed a protein restricted diet (4% casein) for 27 days. Six of these rats were then killed. Groups of 9 rats were fed protein repletion diets consisting of 10%, 20%, or 40% casein for the next 7 days. A control group of 10 rats was fed a diet containing 20% casein for the entire study. Body weight change, food efficiency ratio, liver, kidney, and heart weights, and serum total protein concentration were assessed. Protein depletion depressed weight gain and serum protein concentration, both of which were equally improved among all refeeding groups after 1 week of repletion. Liver and kidney weights were greatest in the groups repleted with 20% and 40% casein. This study indicated that aggressive refeeding of protein provided no benefit with regard to growth or serum protein status, while causing renal and hepatic hypertrophy.

Effects of preparation and cooking of folic acid-fortified foods on the availability of folic acid in a folate depletion/repletion rat model.

The practice of food fortification with folic acid offers the potential to increase the folate intake of the general population. To fully exploit the potential of fortification for raising folate nutriture, appropriate food vehicles need to be selected. Selection should involve determination of the availability of folic acid as affected by characteristics of the carrier food, food matrix, food preparation, and cooking. The present study investigated the effects of preparation and cooking of a range of folic acid-fortified foods on the folate status of folate-deficient rats. Fifty-six weanling male rats (Wistar strain) were fed a folate-deficient diet containing 1% succinyl sulfathiazole for 28 days. Following depletion, six rats were randomly assigned to each of eight repletion diets containing cooked or uncooked meringue mix, quick bread mix, brownie mix, or pizza base mix. The test foods were fortified with 1400 microg of folic acid/kg of food and incorporated as 19% of the repletion diets. Each of the first four groups was pair-fed a diet containing a cooked fortified food with another group fed the corresponding uncooked fortified food. After a further 28 days, plasma, liver, and kidney folate concentrations were determined by microbiological assay. Mean plasma and liver folate concentrations of rats fed diets containing cooked fortified foods were similar to those of rats fed uncooked fortified foods. Preparation and cooking did not affect the availability of folic acid from the selected cereal-based convenience foods in this rat model system, suggesting that these foods are appropriate vehicles for fortification with folic acid.

Influence of folic acid-fortified foods on folate status in a folate depletion-repletion rat model.

An increasing number of foods fortified with varying levels of folic acid are appearing in the market place, targeted either at the general population or at specific consumer groups. Although it is assumed that the folate in these products should be highly bioavailable, there is a need to carry out studies to ascertain that this is, in fact, the case. The present study investigated the ability of selected folic acid-fortified foods (targeted at different types of consumer) to increase the folate status of folate-deficient rats. Forty-two weanling male rats (Wistar strain) were fed a folate-deficient diet containing 1 % succinyl sulfathiazole (w/w) for 28 d. Following depletion, seven rats were randomly assigned to each of five repletion diets containing folic acid, Complan, Slim Fast, Opti-Fuel2 or Cola Coa calculated to provide 200 microg folate/kg of each diet. Calculations were based on folate information from the product labels. After a further 28 d, plasma, liver and kidney folate concentrations were determined by microbiological assay. Plasma homocysteine was measured by HPLC as a functional indicator of folate status. The folate content of the foods was measured by tri-enzyme extraction followed by microbiological assay. Our analyses suggest that there may be considerable inaccuracies on the part of the manufacturers in relation to the folate declarations on the product labels. Despite this, the four foods evaluated were highly effective in elevating plasma, liver and kidney folate and lowering plasma homocysteine concentrations in rats. These results lend support to the policy of food fortification with folic acid as a means of raising the folate status of the population, and in particular to the fortification of specific foods which may target areas of the population where increased folate status is most needed.

Reversal of docosahexaenoic acid deficiency in the rat brain, retina, liver, and serum

The loss of docosahexaenoic acid (DHA) from the retina or brain has been associated with a loss in nervous-system function in experimental animals, as well as in human infants fed vegetable oil-based formulas. The reversibility of the loss of DHA and the compensation by an increase in the n-6 docosapentaenoic acid (DPAn-6) was studied in young adult rats. Long-Evans rats were subjected to a very low level of n-3 fatty acids through two generations. The F2 generation, n-3-deficient animals at 7 weeks of age were provided a repletion diet containing both α-linolenate and DHA. A separate group of F2 generation rats had been maintained on an n-3-adequate diet of the same composition. Tissues from the brain, retina, liver, and serum were collected on weeks 0, 1, 2, 4, and 8 from both groups of animals. The concentrations of DHA, DPAn-6, and other fatty acids were determined and the rate of recovery and length of time needed to complete DHA recovery were determined for each tissue. The DHA level in the brain at 1 and 2 weeks after diet reversal was only partially recovered, rising to approximately 20% and 35%, respectively, of the n-3-adequate group level. Full recovery was not obtained until 8 weeks after initiation of the repletion diet. Although the initial rate of retinal DHA accretion was greater than that of brain DHA, the half-time for DHA recovery was only marginally greater. On the other hand, the levels of DHA in the serum and liver were approximately 90% and 100% replaced, respectively, within 2 weeks of diet reversal. A consideration of the total amounts and time courses of DHA repleted in the nervous system compared with the liver and circulation suggests that transport-related processes may limit the rate of DHA repletion in the retina and brain. —Moriguchi, T., J. Loewke, M. Garrison, J. N. Catalan, N. Salem, Jr. Reversal of docosahexaenoic acid deficiency in the rat brain, retina, liver, and serum.

Meat enhances nonheme iron absorption in pigs

Human subjects absorb heme iron (Fe) more efficiently than nonheme Fe under most conditions. Meat enhances nonheme Fe absorption from most diets. It is not known whether these effects also occur in the pig, a promising model for human Fe absorption studies. The objective of this study was to compare Fe bioavailability from diets containing nonheme Fe (NHI), nonheme Fe with meat (NHI/M) and heme Fe (HI) in the weanling pig. Iron bioavailability was measured by hemoglobin (Hb) repletion assay. Diets were formulated to contain 150 mg Fe/kg diet. Nonheme Fe was supplied as ferric citrate and heme Fe as dried animal red blood cells. Pigs were made anemic by reducing the standard Fe injection at birth to 30 mg and feeding a low Fe transition diet post-weaning until age 41 days. At 41 days of age, pigs were assigned to 3 groups of 8 animals such that mean Hb concentration and body weight of each group were nearly equal. Groups were randomly assigned to 1 of 3 repletion diets. After 7 days feeding, Hb repletion efficiency (HRE) was 21.8% in pigs fed the NHI/M diet compared to 11.2% and 9.1% in pigs fed the NHI or HI diets, respectively. The results presented here demonstrate that, in Fe-deficient weanling pigs, meat increases nonheme Fe bioavailability from corn-based diets while heme Fe, supplied by dried animal red blood cells, is no more bioavailable than Fe from ferric citrate. The results of this study provide further evidence of the validity of the pig model for studying food Fe bioavailability.

Genomic DNA methylation decreases in response to moderate folate depletion in elderly women

Methylation of genomic DNA is dependent on an adequate supply of folate coenzymes. Previous data support the hypothesis that abnormal DNA methylation plays an integral role in carcinogenesis. To date, no studies assessing the effect of inadequate folate status on DNA methylation in older women (aged >63 y) have been reported. The effect of moderate folate depletion followed by folate repletion on leukocyte genomic DNA methylation was investigated in elderly women (aged 60-85 y) to evaluate whether DNA methylation could be used as a functional indicator of folate status. Healthy, postmenopausal women (n = 33) consumed a moderately folate-depleted diet (118 microg folate/d) for 7 wk, followed by 7 wk of folate repletion with 200 or 415 microg/d, each provided as 2 different dietary treatments for a total of 4 treatment groups (n = 30). Leukocyte DNA methylation was determined on the basis of the ability of DNA to incorporate [(3)H]methyl groups from labeled S:-adenosylmethionine in an in vitro assay. Incorporation of [(3)H]methyl groups increased significantly (P: = 0.0025) in response to folate depletion, suggesting undermethylation of DNA. No significant changes were detected in [(3)H]methyl incorporation in any group over the 7-wk repletion period compared with postdepletion values. DNA methylation status may be used as a functional indicator of moderately depleted folate status. The slow response to the repletion diets observed suggests that normalization of DNA methylation after moderate folate depletion may be delayed in older women.

Folate Status of Elderly Women following Moderate Folate Depletion Responds Only to a Higher Folate Intake

Dietary Reference Intakes (DRI) for folate for elderly women have been based primarily on data extrapolated from studies in younger women. This study was conducted to provide the first age-specific data in elderly women (60-85 y) from a controlled metabolic study on which to base folate intake recommendations. Subjects (n = 33) consumed a moderately folate-deplete (118 microg/d) diet for 7 wk, followed by repletion diets providing either 200 or 415 microg folate/d as diet plus folic acid (FA) or a combination of FA and orange juice (OJ) for 7 wk (n = 30). Comparisons among and within groups were made for serum folate (SF), RBC folate and plasma total homocysteine (tHcy) concentrations. SF concentrations decreased significantly (P < 0.001) during depletion (65 +/- 15%). Postrepletion, the adjusted SF concentration for subjects consuming 415 microg folate/d was significantly greater (P = 0.003) than for subjects consuming 200 microg folate/d. RBC folate concentrations decreased (P < 0.001) during depletion (21 +/- 10%) and further (P < 0.001) during repletion (5 +/- 14%). During depletion, plasma tHcy concentrations increased significantly (P < 0.001) and an inverse relationship between SF and plasma tHcy concentrations was observed in 94% of subjects (P < 0.001). Reversal of this inverse relationship was significant only for subjects consuming 415 microg folate/d (P < 0.001). Postrepletion, subjects consuming 200 microg folate/d had a significantly higher (P = 0.009) adjusted plasma tHcy concentration than subjects consuming 415 microg folate/d. These data in elderly women indicate that 415 microg/d folate, provided as a combination of diet, FA and OJ, or diet and FA, normalizes folate status more effectively than does 200 microg/d, thus providing age-specific data for future folate intake recommendations.

Effect of soybean hull iron on growth, iron bioavailability, and behavioral function in anemic rats induced by iron deficiency during gestation or lactation

Bioavailability of iron in soybean hull was investigated by hemoglobin regeneration efficiency (HRE), body iron status and maze test in rat pups with iron-deficiency anemia (IDA) induced by iron deficiency of dams during gestation or lactation (GID or LID group, respectively) and normal pups (N group). The soybean hull repletion diet (SH) and purified control diet (PC) as the experimental diets contained the same amount of iron (35mg/kg diet) and the pups in each group were divided into two subgroups by diet sources. The normal (N-SH), gestation iron deficiency (GID-SH), lactation iron deficiency (LID-SH) groups fed SH were significantly higher in food intake and growth than each of their respective control groups (N-PC, GID-PC, LID-PC) fed PC. After the feeding, hemoglobin concentrations approached normal value in all groups, but HRE were significantly higher with SH irrespective of iron deficient period. IDA rats in either lactation or gestation, when compared to normal rats, resulted in lower serum iron and transferrin saturation. Iron concentrations in both liver and spleen were significantly lower in LID-PC group than LID-SH and N-PC groups. The maze test showed a learning defect in either LID group, but GID groups were not significantly different in comparison with N groups. These results suggest that IDA in lactation may influence more serious growth and development than those in gestation, soybean hull iron has the higher bioavailability in normal and IDA-induced rats, and thus soybean hull is effective as source of iron supplement.

Phosphorus repletion of cattle previously exposed to dietary nitrogen and phosphorus deficiencies

This work reports the effects on growth and metabolic performance of steers fed 2 levels of phosphorus (P) during their repletion from a 15-week depletion period when they were fed diets containing various levels of nitrogen (N) and P. The repletion diets containing either 5·6 g P/day (marginal) or 8·3 g P/day (high) were fed to steers for a period of 12 weeks and were based on barley straw, molasses, sorghum grain, urea, and formaldehyde-treated gluten [mean dry matter (DM) digestibility of 0·62 and 14·6 g N/kg DM]. These repletion diets were formulated to simulate the dietary regimens of cattle grazing wet-season pastures in northern Australia and other tropical and subtropical regions. Food intake, liveweight gain, plasma metabolites, and P kinetics were measured. There was no significant difference between the repletion marginal- and high-P treatments in the mean liveweight (LW) gains and DM intakes (g/kg LW) of the steers. However, for both P treatments, the steers that had been fed a suboptimal level of N during depletion had marked increases (&gt;60%) in feed intake throughout the repletion period. Within the marginal-P treatment, the growth rates of steers that had been fed a suboptimal level of N during depletion were higher than for those that had been fed higher N levels, and were similar to those of the high-P groups. Plasma inorganic P, bone thickness, and bone P concentration remained lower for the marginal-P treatment at the end of the repletion period. Furthermore, within the marginal-P treatment, steers that had been fed the high-N diet during depletion were unable to increase bone thickness and had lower growth rates than anticipated for the quality of the diet. Although N balance was positive and similar for both P treatments, the apparent P balance for the marginal-P treatment of 7·6 mg/kg LW was only about half that of the high-P treatment. It was concluded that the requirement for dietary P in steers that had been exposed to a dietary P deficiency, particularly when in association with high N, was higher than the 5·6 g/day provided.

Adding ascorbic acid to iron-fortified cow's milk does not enhance iron bioavailability to piglets

Objectives of this research were to assess the effect of ascorbic acid on iron bioavailability from iron-fortified cow's milk and to evaluate the infant pig as a model for iron bioavailability studies. Iron bioavailability was measured by hemoglobin repletion assay. Piglets were made anemic by withholding the iron injections normally given at birth. Piglets from a single litter were weaned at age 14 days and divided into 2 groups of 4 on the basis of sex and hemoglobin concentration. The groups were randomly assigned to dietary treatments. The diets were based on pasteurized homogenized whole milk and were formulated to meet swine nutrient requirements. Both diets contained 0.25 mM FeCl 3 (14 mg/L diet) and were identical except that one was fortified with L-ascorbic acid to a concentration of 2.5 mM (0.44 g/L diet). Piglets were fed repletion diets for 10 days. The experiment was replicated with an additional 8 piglets from another litter. Means of the initial/final hemoglobin concentrations were 5.89 10.21 and 6.25 9.69 g/dL for the ascorbic acid fortified and unfortified diets, respectively. No significant difference in hemoglobin regeneration efficiencies of the treatment groups was observed (p=0.632).

Choline deficiency and methotrexate treatment induces marked but reversible changes in hepatic folate concentrations, serum homocysteine and DNA methylation rates in rats.

The study compared the effects of feeding rats a choline deficient (CD) diet or injecting low doses of methotrexate (MTX) on hepatic folate concentration and distribution, homocysteine (Hcy) concentration and DNA methylation. Thirty rats were divided into three groups and were fed either a choline sufficient (CS) or deficient diet (CD), or injected with low doses of MTX (0.1 mg/kg/day) for 2 weeks. Half the animals of each group were sacrificed and the remaining CD and MTX animals were fed repletion diets without methotrexate administration for two additional weeks. CD or MTX resulted in a significantly lower folate concentrations (25-50%) compared to the control group. Folate distribution in the treated animals was associated with elongation of the glutamate chains: higher proportion of hexa (from 14%, control, to 35%, choline, p < 0.05), hepta (from 5% to 16%, p < 0.05), and appearance of octaglutamyl folates. MTX administration resulted in a similar pattern of hepatic folate distribution. Two weeks following the MTX administration and the restoration of an adequate choline diet for 2 weeks restored the hepatic folate levels to the control animals. Results are discussed based on the possibility that CD and MTX treatment appear to impair the capacity of tissues to incorporate folate in only 2 weeks and affect other biomarkers of one-carbon metabolism such as Hcy concentration and DNA methylation. This adverse picture was partially reversed in a relative short time by simply feeding an adequate CS diet and discontinuing MTX injections.