Dietary Ca Research Articles

Dietary calcium requirement of bullfrog (Lithobates catesbeiana)

This study was conducted to determine dietary calcium (Ca) requirement of bullfrog (Lithobates catesbeiana). Six diets were formulated to contain 0.55% (control), 0.96%, 1.30%, 1.72%, 2.02% and 2.53% Ca. Each diet was fed to triplicate tanks of bullfrogs (24.96 ± 0.03 g), and each tanks was stocked with 13 bullfrogs. Bullfrogs were fed twice daily (8:30 and 17:30) to apparent satiation for 8 weeks. Weight gain rate of bullfrogs fed the 1.72% Ca diet was significantly higher than the control group (P < 0.05). The content of Ca was significantly increased in the whole body and vertebrae of bullfrogs fed the 1.72%, 2.02% and 2.53% diets compared to those fed the 0.55%, 0.96% and 1.30% Ca diets (P < 0.05). Furthermore, bullfrogs fed the 1.30%, 1.72% and 2.02% diets had higher activity of trypsin than those fed the 0.55% and 2.53% Ca diets (P < 0.05). Apparent digestibility coefficient of dry matter was higher in bullfrogs fed the 1.72% Ca diet than those fed the 0.55% and 2.53% diets (P < 0.05). Bullfrogs fed the 1.72% Ca diet had higher activity of superoxide dismutase in the serum than those fed the 0.55% and 2.53% diets (P < 0.05). Compared to the control group, contents of 1,25 dihydroxyvitamin D3 and parathyroid hormone in the serum as well as vitamin D receptor and sodium-calcium exchanger genes expression in the kidney were significantly decreased in bullfrogs fed the 1.72%, 2.02% and 2.53% Ca diets (P < 0.05). Compared to the control group, intestinal sodium-calcium exchanger gene expression was significantly decreased in bullfrogs fed the 1.72% and 2.02% Ca diets (P < 0.05). Based on second order polynomial analysis of weight gain rate, dietary Ca requirement of bullfrog was 1.89%.

Total Calcium Intake Is Associated With Trabecular Bone Density in Adolescent Girls With Type 1 Diabetes.

Type 1 diabetes (T1D) confers an increased risk of fracture and is associated with lower bone mineral density (BMD) and altered microarchitecture compared with controls. Adequate calcium (Ca) intake promotes bone mineralization, thereby increasing BMD. The objective of this analysis was to evaluate the associations of total daily Ca intake with bone outcomes among youth with T1D. This was a cross-sectional analysis of girls ages 10-16 years with (n = 62) and without (n = 60) T1D. We measured Ca intake with a validated food-frequency questionnaire and BMD, microarchitecture, and strength estimates with dual-energy X-ray absorptiometry and high-resolution peripheral quantitative computed tomography. Total daily Ca intake did not differ between groups (950 ± 488 in T1D versus 862 ± 461 mg/d in controls, p = 0.306). Serum 25OHD was lower in T1D (26.3 ± 7.6 versus 32.6 ± 9.0 ng/mL, p = <0.001), and parathyroid hormone (PTH) was higher in T1D (38.9 ± 11 versus 33.4 ± 9.7 pg/mL, p = 0.004). Trabecular volumetric BMD and thickness at the tibia were lower in T1D (p = 0.013, p = 0.030). Ca intake correlated with trabecular BMD at the radius and tibia among T1D participants (β = 0.27, p = 0.047, and β = 0.28, p = 0.027, β = 0.28, respectively) but not among controls (pinteraction = 0.009 at the radius, pinteraction = 0.010 at the tibia). Similarly, Ca intake was associated with estimated failure load at the tibia in T1D but not control participants (p = 0.038, β = 0.18; pinteraction = 0.051). We observed the expected negative association of Ca intake with parathyroid hormone in controls (p = 0.022, β = -0.29) but not in T1D participants (pinteraction = 0.022). Average glycemia as measured by hemoglobin A1c did not influence the relationship of Ca and PTH among participants with T1D (pinteraction = 0.138). These data suggest that youth with T1D may be particularly vulnerable to dietary Ca insufficiency. Increasing Ca intake may be an effective strategy to optimize bone health in this population. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Rabbits (Oryctolagus cuniculus) increase caecal calcium absorption at increasing dietary calcium levels.

Hindgut fermenting herbivores from different vertebrate taxa, including tortoises, and among mammals some afrotheria, perissodactyla incl. equids, several rodents as well as lagomorphs absorb more calcium (Ca) from the digesta than they require, and excrete the surplus via urine. Both proximate and ultimate causes are elusive. It was suggested that this mechanism might ensure phosphorus availability for the hindgut microbiome by removing potentially complex-building Ca from the digesta. Here we use Ussing chamber experiments to show that rabbits (Oryctolagus cuniculus) maintained on four different diets (six animals/diet) increase active Ca absorption at increasing Ca levels. This contradicts the common assumption that at higher dietary levels, where passive uptake should be more prevalent, active transport can relaxand hence supports the deliberate removal hypothesis. In the rabbits, this absorption was distinctively higher in the caecum than in the duodenum, which is unexpected in mammals. Additional quantification of the presence of two proteins involved in active Ca absorption (calbindin-D9K CB; vitamin D receptor, VDR) showed higher presence with higher dietary Ca. However, their detailed distribution across the intestinal tract and the diet groups suggests that other factors not investigated in this study must play major roles in Ca absorption in rabbits. Investigating strategies of herbivores to mitigate potential negative effects of Ca in the digesta on microbial activity and growth might represent a promising area of future research.

Negative dietary cation-anion difference and amount of calcium in prepartum diets: Effects on urine and serum minerals

Negative dietary cation-anion difference (DCAD) diets fed prepartum induce a compensated metabolic acidosis, which stimulates metabolic Ca flux before calving and decreases clinical and subclinical hypocalcemia after calving. Effects of low or high dietary Ca in these diets are unclear. Our objective was to determine the effects of inducing a prepartum metabolic acidosis and the amount of dietary Ca on urinary mineral excretion and serum mineral concentrations during the transition period in multiparous Holstein cows (n = 81). Treatment diets fed during the last 28 d before calving were (1) positive DCAD, +6 mEq/100 g of dry matter (DM), target urine pH >7.5, low dietary Ca (0.40% DM; CON); (2) negative DCAD, −24 mEq/100 g of DM, target urine pH 5.5 to 6.0, low dietary Ca (0.40% DM; ND); or (3) negative DCAD, −24 mEq/100 g of DM, target urine pH 5.5 to 6.0, high dietary Ca (2.0% DM; NDCA). Urine was sampled on −21, −14, −7, +1, +2, and +7 d relative to calving. Blood samples were collected on d −30, −21, −14, −7, −4, −2, −1, 0, 1, 2, and 4 relative to parturition. Preplanned treatment contrasts were (1) CON versus ND and NDCA, and (2) ND versus NDCA. Cows fed ND or NDCA had increased urinary volume and excretion of Ca, Cl, and SO4−2, along with decreased excretion of K. Supplementation of Ca to the acidogenic diet increased urinary excretion of Ca at d −21, but this difference lessened as cows approached parturition. Additional Ca increased prepartum urinary excretion of K and Cl. Differences in excretion decreased quickly after parturition, although urinary excretion of Cl remained greater for cows previously fed negative DCAD diets. Acidogenic diets increased serum K and Cl concentrations prepartum. Supplemental Ca decreased serum P relative to ND. During d 0 to 4, serum P and K were greater for cows fed ND or NDCA than for cows fed CON; these differences disappeared by d 4. Acidogenic diets increased serum Ca by increasing Ca flux and excretion in urine. Supplemental Ca in the acidogenic diet modestly increased Ca excretion early in the close-up period.

Dietary calcium (Ca2+) impacts Ca2+ content and molecular expression of Ca2+-transporters in Malpighian tubules of the yellow fever mosquito, Aedes aegypti

The renal (Malpighian) tubules of insects play important roles in hemolymph Ca2+ regulation. Here we investigated how dietary Ca2+ loads from sucrose or blood meals affect the Ca2+ content and mRNA expression of Ca2+ transporters in Malpighian tubules of adult female mosquitoes. Using the yellow fever mosquito Aedes aegypti we found that feeding females 10% sucrose with elevated Ca2+ concentration ad libitum for 6 days led to increased Ca2+ content in Malpighian tubules. The increases of Ca2+ content correlated with up-regulations of mRNAs encoding intracellular Ca2+-ATPases (SERCA and SPCA), a plasma membrane Ca2+-ATPase (PMCA), and a K+-dependent Na+/Ca2+ exchanger (NCKX1). We also found that when adult females were fed blood, tubule Ca2+ content changed dynamically over the next 72 h in a manner consistent with redistribution of tubule Ca2+ stores to other tissues (e.g., ovaries). The changes in tubule Ca2+ were correlated with dynamic changes in mRNA abundances of SERCA, SPCA, PMCA, and NCKX1. Our results are the first to demonstrate that Malpighian tubules of adult female mosquitoes have a remarkable capacity to handle high dietary Ca2+ loads, most likely through the combination of storing excess Ca2+ within intracellular compartments and secreting it into the tubule lumen for excretion. Our results also suggest that the Malpighian tubules play key roles in supplying Ca2+ to other tissues during the processing of blood meals.

Effects of essential mineral elements deficiency and supplementation on serum mineral elements concentration and biochemical parameters in grazing Mongolian sheep.

Traditional sheep grazing is the pillar industry and the main source of income for local herders in the Inner Mongolia Autonomous Region of China. However, grazing sheep often suffer from mineral deficiency. In the present study, the feeding experiment was performed on 84 grazing Wu Ranke sheep. After being divided into calcium (Ca), zinc (Zn), copper (Cu), cobalt (Co), manganese (Mn), and selenium (Se) treatment groups, they were fed with a mineral deficient diet for 60 days and then a mineral supplement diet for 41 days. Serum samples were collected three times, 10 concentrations of essential mineral elements and 15 concentrations/activity of biochemical parameters were measured to assess the effects of mineral deficiency and supplementation on the physical health of sheep. The results revealed that the sheep showed mineral Ca, Cu, Co, Mn, and Se deficiencies after feeding their respective mineral deficient diet. Deficiency in dietary Ca, Zn, Cu, Co, Mn, and Se may adversely affect the liver, myocardium and pancreas of sheep. The prompt supplementation of dietary Zn, Cu, Co, Mn, and Se may alleviate the damage caused to the liver, myocardium and pancreas, while that of dietary Ca improved energy generation. In conclusion, the adequate supplementation of dietary Ca, Zn, Cu, Co, Mn, and Se is essential for avoiding the impairment caused to the liver, myocardium and pancreas function of sheep by the deficiency in essential dietary minerals.

A novel consensus bacterial 6-phytase variant improves the responses of laying hens fed an inorganic phosphorus-free diet with reduced energy and nutrients from 23 to 72 wk of age

The objective of this study was to evaluate the effect of a novel consensus bacterial 6-phytase variant (PhyG) on egg productivity, eggshell quality, and body composition of laying hens fed inorganic phosphate-free diets with reduced energy and nutrients from 23 to 72 wk of age. Five treatments were randomly assigned, performing 28 replicates per treatment with 4 hens each, totaling 560 Hy-Line W80 birds. A positive control (PC) feed was formulated to contain adequate levels of energy and nutrients. A negative control (NC) feed was formulated without added inorganic phosphate (0.12% nonphytic phosphorus [nPP]) and reduced in Ca, Na, dig AA, and metabolizable energy in comparison with PC feed. Phytase was supplemented in the NC feed at 0, 300, 600, and 900 FTU/kg of feed. The responses evaluated were performance, egg quality, economic analysis, body composition, and tibia composition. Data were analyzed by a 2-factor (diet and age) repeated measure analysis. Overall, the feed intake, hen-day egg production, egg mass, and egg revenue were reduced by the complete removal of dicalcium phosphate (DCP) (P < 0.05). Supplement phytase in the NC diet elicits a positive response on each one of those variables. Laying hens consuming the NC feed with 900 FTU/kg of phytase produced more eggs per hen-housed compared with the phytase dosages of 300 and 600 FTU/kg. Body composition was not affected by dietary nPP, Ca, Na, dig AA, and energy reductions (P > 0.05). At 72-wk-old, tibia ash was reduced in hens consuming the NC diet vs. PC (P < 0.05) and no difference was observed between hens supplemented with phytase and the PC feed. Margin over feeding cost increased in a dose-dependent manner with phytase supplementation. Supplementation with 900 FTU/kg of phytase is recommended to improve the number of eggs produced per hen-housed and the number of marketable eggs produced through 23 to 72 wk of age, under this dietary setting.

Association of bone mineralization markers with dietary nutrient intake in adolescents with and without biochemical osteomalacia.

Dietary intake is widely known to play a crucial role in achieving peak bone mass among children and adolescents. Unfortunately, this information is lacking among Arab adolescents, an understudied demographic that has recently been observed to have a high prevalence of abnormal mineralization markers [low serum 25(OH)D, high serum alkaline phosphatase (ALP), low calcium (Ca) and/or inorganic phosphate (Pi)] suggestive of biochemical osteomalacia (OM, defined as any 2 of the 4 parameters). In order to fill this gap, we aimed to evaluate the associations of serum markers of biochemical OM with dietary intake of macronutrients, vitamins and trace minerals. Saudi adolescents (N = 2,938, 57.8% girls), aged 12-17 years from 60 different schools in Riyadh, Saudi Arabia were included. Dietary intake of nutrients was calculated following a semi-quantitative 24 h dietary recall over 3 weekdays and 1 weekend-day using a validated food frequency questionnaire. Compliance to reference daily intake (RDI) of macronutrients, vitamins and trace minerals were calculated. Fasting blood samples were collected and circulating levels of 25(OH)D, ALP, Ca, and Pi were analyzed. A total of 1819 (1,083 girls and 736 boys) adolescents provided the dietary recall data. Biochemical OM was identified in 175 (9.6%) participants (13.5% in girls, 3.9% in boys, p < 0.01) while the rest served as controls (N = 1,644). All participants had serum 25(OH)D levels <50 nmoL/L. Most participants had very low dietary intakes of Ca (median ~ 290 mg) and vitamin D (median ~ 4 μg) which are far below the RDI of 1,300 mg/day and 20 μg/day, respectively. In contrast, excess dietary intakes of Pi, Na, K, and Fe were observed in all participants. In the biochemical OM group, thiamine and protein intake were significant predictors of serum 25(OH)D, explaining 4.3% of the variance perceived (r = 0.23, adjusted r2 = 4.3%, p = 0.01). Among controls, dietary vitamin C and vitamin D explained 0.6% of the total variation in serum 25(OH)D (r = 0.09, adjusted r2 = 0.6%, p = 0.004). Arab adolescents do not meet the RDI for dietary Ca and vitamin D, and none have sufficient vitamin D status (25(OH)D levels >50 nmol/L) but they exceed the RDI for dietary Pi. Interpreting these data in the light of the increased prevalence of rickets in Arab countries, food fortification to optimise vitamin D and Ca intake in Saudi adolescents should be considered.

Calcium and boron alone or in combination influence performances and mineral metabolism in broilers

An experiment was conducted to study the effect of dietary boron supplementation on performance and mineral metabolism in broilers fed a diet with optimal or sub-optimal levels of calcium. A total of 216 one-day old broiler chicks (Vencob) of mixed sex (mean BW 43.79±0.83 g) were distributed in completely randomized design into six treatments each with three replicates of 12 birds (6 of each sex). The six dietary treatment groups comprised of B0C0 (basal diet with normal calcium (10 g Ca/kg)), B0C1 (Basal diet of 20% calcium deficiency (8 g Ca/kg)), B0C2 (Basal diet of 40% calcium deficiency (6 g Ca/kg)), B1C0 (Basal diet with normal calcium + 25 mg/kg boron), B1C1 (Basal diet of 20% calcium deficiency + 25 mg/kg boron) and B1C2 (Basal diet of 40% calcium deficiency + 25 mg/kg boron). The performance indices like body weight (BW), weekly body weight gain, feed intake (FI) and feed conversion ratio (FCR) were recorded till 42 d of age. A metabolism trial was conducted at the end to determine the balance of minerals. Lower than the recommended level of calcium alone or with supplemental boron significantly increased the BW, feed intake, and FCR in commercial broilers at six weeks of age. Low dietary calcium significantly increased the retention of calcium, phosphorous, magnesium, iron and manganese. Dietary boron supplementation significantly increased the excreta concentration of iron and manganese. However, the absolute and relative retention of manganese and iron were unaffected when boron was supplemented into a low calcium diet; indicating the negative effect of boron on manganese, and iron metabolism can be compensated by low dietary Ca concentration.

A first model of the fate of dietary calcium and phosphorus in broiler chickens

To reduce P excretion and increase the sustainability of poultry farms, one needs to understand the mechanisms surrounding P metabolism and its close link with Ca metabolism to precisely predict the fate of dietary P and Ca and related requirements for birds. This study describes and evaluates a model developed to estimate the fate of Ca and P consumed by broilers. The Ca and P model relies on three modules: (1) digestion of Ca and P; (2) dynamics of Ca and P in soft tissue and feathers; and (3) dynamics of body ash. Exogenous phytase affects the availability of Ca and P; thus, to predict the absorption of those minerals, the model also accounts for the effect of phytase on Ca and P digestibility. We used a database to estimate the consequences of dietary Ca, P, and phytase over feed intake response. This study followed a four-step process: (1) Ca and P model development and its coupling with a growth broiler model; (2) model behavior assessment; (3) sensitivity analysis to identify the most influential parameters; and (4) external evaluation based on three databases. The proportion of P in body protein and the Ca to P ratio in bone are the most sensitive parameters of P deposition in soft tissue and bone, representing 91 and 99% of the total variation. The external evaluation results indicated that body water and protein had an overall mean square prediction error (rMSPE) of 7.22 and 12.3%, respectively. The prediction of body ash, Ca, and P had an rMSPE of 7.74, 11.0, and 6.56%, respectively, mostly errors of disturbances (72.5, 51.6, and 90.7%, respectively). The rMSPE for P balance was 13.3, 18.4, and 22.8%, respectively, for P retention, excretion, and retention coefficient, with respective errors due to disturbances of 69.1, 99.9, and 51.3%. We demonstrated a mechanistic model approach to predict the dietary effects of Ca and P on broiler chicken responses with low error, including detailed simulations to show the confidence level expected from the model outputs. Overall, this model predicts broilers’ response to dietary Ca and P. The model could aid calculations to minimize P excretion and reduce the impact of broiler production on the environment. A model inversion is ongoing that will enable the calculation of Ca and P dietary quantities for a specific objective. This will simplify the use of the model and the feed formulation process.

Dietary Calcium Intake and Osteoporosis Risk in Arab Adults.

Osteoporosis is a major public health concern in Saudi Arabia's aging population. There is particularly limited information on how diet affects bone loss in this ethnic group. The purpose of this study was to examine the association between dietary calcium (Ca) intake and osteoporosis risk in Saudi adults. A total of 1950 patients (416 males and 1534 females) with known risk factors for osteoporosis participated in this cross-sectional study. A short questionnaire (CaQ) was used to assess dietary Ca intakes in patients attending tertiary hospitals in Riyadh City. The prevalence of osteoporosis was 21.3% and was more common in females (93.5%). Patients with osteoporosis were older (p < 0.001) and had lower BMI (p < 0.001). Results showed that the overall mean Ca intake was only 445.1 mg/day (recommended dietary intake of 1300 mg/day). Tea intake (OR = 0.8 95%CI: 0.7-1.0; p = 0.02) and consumption of fish and eggs (OR = 0.9 95%CI: 0.8-1.0; p = 0.01) were significantly associated with a lower risk of osteoporosis. Furthermore, consumption of biscuits, cake and bread slices were significantly associated with higher incidence of osteoporosis (OR = 1.3 95%CI: 1.0-1.5; p = 0.02). In conclusion, extremely low dietary Ca intake was observed among Saudi adults already at risk of osteoporosis. A balanced diet including high amount of Ca, vitamin D and omega-3 fatty acids accompanied by limiting consumption of foods high in saturated fats and glycemic index may be helpful in reducing osteoporosis risk in the Saudi adult population.

Dietary calcium and nonphosphate phosphorus interaction influences tibiotarsus development and related gene expression of broilers from 1 to 21 days of age

The dietary needs of calcium (Ca) and phosphorus (P) are interdependent, thus accurate evaluation of Ca and P requirements of broilers to support skeleton health and optimal growth is critical. The present study was carried out to investigate the effects of dietary Ca and nonphytate P (NPP) levels and their interactions on growth performance, tibiotarsus characteristics, tibiotarsus metabolism-related enzyme and proteins, and their gene expression of broilers, so as to provide a rational recommendation for Ca and NPP levels in diet. A total of 540 one-day-old Arbor Acres male broilers were randomly allotted to 1 of 15 treatments with 6 replicate cages of 6 birds per cage for each treatment in a completely randomized design involving a 5×3 factorial arrangement of treatments (5 levels of Ca×3 levels of NPP). The birds were fed the corn-soybean meal diet containing 0.60%, 0.70%, 0.80%, 0.90%, or 1.00% Ca and 0.35%, 0.40%, or 0.45% NPP for 21 d. Dietary Ca level affected (P < 0.03) the bone mineral density, bone mineral content (BMC), breaking strength, ash percentage and ash Ca contents in tibia, which showed linear (P < 0.006) responses to dietary Ca levels. Dietary NPP level affected (P < 0.05) tibia BMC, ash percentage, and FGF23 mRNA level. Broilers that received 0.40% and 0.45% NPP had higher (P < 0.04) tibia BMC and ash percentage than those that received 0.35% NPP, but no differences (P > 0.05) were found between 0.40% and 0.45% NPP. Broilers that received 0.40% NPP had higher (P=0.02) tibia FGF23 mRNA level than those that received 0.35% NPP, but no differences (P > 0.05) were detected between 0.40% and 0.45% NPP or 0.45% and 0.35% NPP. The interactions between dietary Ca and NPP affected (P < 0.05) ADG, ALP activity, bone gal protein, FGF23 contents, and the mRNA expression levels ALP and bone gal protein in tibia of broilers. Results from the present study indicate that dietary Ca and NPP interaction influences growth, tibiotarsus development, and related gene expression of broiler chickens. Considering all the criteria, the dietary levels of 0.90% Ca and 0.45% NPP would be optimal for both growth and tibiotarsus development of broilers fed a conventional corn-soybean meal diet from 1 to 21 d of age.

Low Ca diet leads to increased Ca retention by changing the gut flora and ileal pH value in laying hens.

Osteoporosis is a common degenerative metabolic bone disease in caged laying hens. Intensive egg production mobilizing large amounts of Ca from bone for eggshell formation, consequently leading to Ca deficiency, has been recognized as a critical factor causing osteoporosis in commercial laying hens. The aim of this study was to examine the effect of Ca deficiency on the function of the gut microbiota-bone axis and related egg production traits and bone health in laying hens. Twenty-four 48-week-old laying hens were fed a control diet (Control, 3.72%) or a low Ca diet (LC, 2.04%) for 60d (n=12). Compared to the Control hens, the LC hens had higher levels of alkaline phosphatase and tartrate resistant acid phosphatase (P<0.05) with lower bone strength, eggshell thickness, and eggshell strength (P<0.05). In addition, the LC hens had higher plasma estradiol concentrations, while having lower concentrations of interleukin-1 (IL-1) and IL-6. The LC hens also had a lower pH value in the ileum with an increased Ca retention. The principal co-ordinates analysis showed significantly separate cecal microbiota populations between the Control and LC hens. The Prevotellaceae_UCG-001, Subdoligranulum, Peptococcus, and Eubacterium_hallii_group (P<0.05) were higher, while the CHKC1001 and Sutterella (P<0.05) were lower at the genus level in the LC hens. In addition, Prevotellaceae_UCG-001, Subdoligranulum and Eubacterium_hallii_group had a negative correlation, while Sutterella was positively correlated with ileal pH values. The transcriptome analysis revealed that the low Ca diet caused 20 and 31 genes to be significantly up- and down-regulated, respectively. The gene expressions of cystic fibrosis transmembrane conductance regulator, solute carrier family 26 member 3 of the anion exchangers, and mitogen-activated protein kinase 12 of pro-inflammatory factors were lower in the LC birds, which was correlated with the lower ileal pH values. These results suggest that the hens with low Ca diet-induced osteoporosis have an increased intestinal Ca retention with a decreased ileal pH value, correlated with the changes in Prevotellaceae_UCG-001, Subdoligranulum, and Eubacterium_hallii_group of beneficial genera. The results provide insights for further understanding and preventing osteoporosis in laying hens.

Reduced dietary Ca, Cu, Zn, Mn, and Mg bioavailability but increased Fe bioavailability with polyethylene microplastic ingestion in a mouse model: Changes in intestinal permeability and gut metabolites

Microplastics emerge as a new environmental and human health crisis. Minimal research exists on effects of microplastic ingestion on the oral bioavailability of minerals (Fe, Ca, Cu, Zn, Mn, and Mg) in the gastrointestinal tract via impacting intestinal permeability, mineral transcellular transporters, and gut metabolites. Here, mice were exposed to polyethylene spheres of 30 and 200 μm (PE-30 and PE-200) in diet (2, 20, and 200 μg PE g−1) for 35 d to determine the microplastic effects on mineral oral bioavailability. Results showed that for mice fed diet amended with PE-30 and PE-200 at 2–200 μg g−1, Ca, Cu, Zn, Mn, and Mg concentrations in the small intestine tissue were 43.3–68.8 %, 28.6–52.4 %, 19.3–27.1 %, 12.9–29.9 %, and 10.2–22.4 % lower compared to control mice, suggesting hampered bioavailability of these minerals. In addition, Ca and Mg concentrations in mouse femur were 10.6 % and 11.0 % lower with PE-200 at 200 μg g−1. In contrast, Fe bioavailability was elevated, as suggested by significantly (p < 0.05) higher Fe concentration in the intestine tissue of mice exposed to PE-200 than control mice (157–180 vs. 115 ± 7.58 μg Fe g−1) and significantly (p < 0.05) higher Fe concentrations in liver and kidney with PE-30 and PE-200 at 200 μg g−1. Following PE-200 exposure at 200 μg g−1, genes coding for duodenal expression of tight junction proteins (e.g., claudin 4, occludin, zona occludins 1, and cingulin) were significantly up-regulated, possibility weakening intestinal permeability to Ca, Cu, Zn, Mn, and Mg ions. The elevated Fe bioavailability was possibly related to microplastic-induced greater abundances of small peptides in the intestinal tract, which inhibited Fe precipitation and elevated Fe solubility. Results showed that microplastic ingestion may cause Ca, Cu, Zn, Mn, and Mg deficiency but Fe overload via altering intestinal permeability and gut metabolites, posing a threat to human nutrition health.

Determination of TMEn, standardized amino acid digestibility, phosphorus digestibility, and phosphorus bioavailability in conventional and reduced phosphorus distillers dried grains with solubles

The TMEn, amino acid (AA) digestibility, and P availability in 2 conventional corn distillers dried grains with solubles (C-DDGS1 and 2; 0.86 to 1.14% P, DM basis) and reduced phosphorus DDGS (RP-DDGS; 0.39% P) were evaluated. The TMEn of C-DDGS1 and 2 and RP-DDGS were determined in Experiment 1 using conventional adult Leghorn roosters, while standardized AA digestibility was determined in Experiment 2 using cecectomized roosters. Apparent ileal digestibility (AID) of P at different Ca levels was determined using precision-fed (crop intubation) broiler chickens in Experiments 3 and 4. The AID and total tract retention of P in C-DDGS2 were evaluated in Experiment 5 using ad libitum-fed broilers. Phosphorus bioavailability in C-DDGS2 relative to KH2PO4 based on bone ash was determined in Experiment 6. Experiments contained 4 to 5 replicates per treatment. In Experiment 1, the TMEn of C-DDGS1 and RP-DDGS was 3,428 and 2,840 kcal/kg, respectively (DM basis). In Experiment 2, there were no differences (P > 0.05) in rooster AA digestibility values between C-DDGS1 and RP-DDGS. In Experiment 3 with precision-fed chicks, AID of P in C-DDGS1 and RP-DDGS was 81 and 59%, respectively; there was no effect (P > 0.05) of increasing dietary Ca level from 0.04 to 1.0% for C-DDGS1 or reducing Ca from 1.5 to 1.0% for RP-DDGS. The AID of P in precision-fed chicks for C-DDGS2 in Experiment 4 was 48 and 80% at 1.3 and 0.3 Ca:total P ratios, respectively (P < 0.05). In Experiment 5, AID of P in C-DDGS2 at Ca:total P ratios of 1.3 and 2.5 was 63 and 42%, respectively, in precision-fed chicks. Regression of bone ash content (mg/tibia) on supplemental P intake in Experiment 6 yielded a P bioavailability of 61% relative to KH2PO4 for C-DDGS2. In conclusion, total and digestible P content in RP-DDGS was greatly reduced compared with C-DDGS, and the digestibility and bioavailability of the P in C-DDGS was affected by type of experimental assay and dietary Ca level.

Dietary magnesium and calcium intake is associated with lower risk of hearing loss in older adults: A cross-sectional study of NHANES.

Dietary intake as a modifiable factor has been reported to be associated with hearing loss (HL). The relationship between magnesium (Mg) and calcium (Ca) as common dietary nutrients and HL in the elderly has rarely been reported. This study aimed to assess the association between Mg and Ca intake and HL in older adults. This cross-sectional study included participants aged ≥70 years from the National Health and Nutrition Examination Survey (NHANES) 2005-2006, 2009-2010, and 2017-2018. Outcomes were low-frequency [pure-tone averages (PTAs) at 500, 1000, and 2000 Hz >25 dB] and speech-frequency (PTAs at 500, 1000, 2000, and 4,000 Hz >25 dB) HL. Multivariate logistic analysis was utilized to explore the association between dietary Mg and Ca intake and their combined intake (Ca/Mg, Ca*Mg) and HL, and was described as odds ratio (OR) and 95% confidence interval (CI). A total of 1,858 participants were included, of which 1,052 (55.95%) had low-frequency HL and 1,349 (72.62%) had speech-frequency HL. Dietary Ca intakes [OR = 0.86, 95%CI: (0.74-0.99)] and Mg intakes [OR = 0.81, 95%CI: (0.68-0.95)] and Ca * Mg [OR = 0.12, 95%CI: (0.02-0.87)] were associated with lower odds of low-frequency HL after adjusting for confounders. Similar, dietary Ca intakes [OR = 0.85, 95%CI: (0.77-0.95)] and Mg intakes [OR = 0.78, 95%CI: (0.68-0.90)] and Ca * Mg [OR = 0.23, 95%CI: (0.05-0.78)] were related to lower odds of speech-frequency HL. For different levels of Mg and Ca intake, the combined intake of Ca (≥1,044 mg) and Mg (≥330 mg) was related to lower odds of low-frequency HL [OR = 0.02, 95%CI: (0.00-0.27)] and speech-frequency HL [OR = 0.44, 95%CI: (0.21-0.89)]. Dietary intakes of Mg and Ca were associated with lower odds of HL and are a promising intervention to be further explored in older adults with HL.

Intestinal Vitamin D Receptor Is Dispensable for Maintaining Adult Bone Mass in Mice With Adequate Calcium Intake.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3)-mediated intestinal calcium (Ca) absorption supplies Ca for proper bone mineralization during growth. We tested whether vitamin D receptor (VDR)-mediated 1,25(OH)2D3 signaling is critical for adult Ca absorption and bone by using mice with inducible Vdr gene knockout in the whole intestine (villin-CreERT2+/- × Vdrf/f, WIK) or in the large intestine (Cdx2-CreERT2+/- ×Vdrf/f, LIK). At 4-month-old, Vdr alleles were recombined (0.05 mg tamoxifen/g BW, intraperitoneally [i.p.], 5 days) and mice were fed diets with either 0.5% (adequate) or 0.2% (low) Ca. Ca absorption was examined after 2 weeks while serum 1,25(OH)2D3, bone mass, and bone microarchitecture were examined after 16 weeks. Intestinal and renal gene expression was measured at both time points (n = 12/genotype/diet/time point). On the 0.5% Ca diet, all phenotypes in WIK and LIK mice were similar to the controls. Control mice adapted to the 0.2% low-Ca diet by increasing renal Cyp27b1 mRNA (3-fold), serum 1,25(OH)2D3 level (1.9-fold), and Ca absorption in the duodenum (Dd, + 131%) and proximal colon (PCo, + 28.9%), which prevented bone loss. In WIK mice, low-Ca diet increased serum 1,25(OH)2D3 (4.4-fold) but Ca absorption remained unaltered in the Dd and PCo. Consequently, significant bone loss occurred in WIK mice (e.g., cortical thickness, Ct.Th, -33.7%). LIK mice adapted to the low-Ca diet in the Dd but not the PCo, and the effect on bone phenotypes was milder (e.g., Ct.Th, -13.1%). Our data suggest intestinal VDR in adult mice prevents bone loss under low Ca intake but is dispensable under adequate calcium intake.

Long-term effects of dietary calcium and phosphorus level, and feed form during rearing on egg production, eggshell quality, and bone traits in brown laying hens from 30 to 89 wk of age

The effects of feeding strategies during rearing (0-16 wk) of brown laying hens on mid and end laying performance (30-89 wk) were studied. The rearing feeding strategies followed a 3×2 factorial arrangement with feed form; mash with inclusion of 3% finely ground wheat straw (MWS), crumbles with inclusion of 3% finely ground wheat straw (CWS), and crumbles with inclusion of 3% unground oat hulls as fiber sources (COH) at 2 dietary Ca and P levels (high or low Ca-P). Feed conversion ratio improved with COH and MWS compared with CWS from 30 to 59 wk. Rate of lay and egg mass production showed a feed form×Ca-P interaction from 60 to 89 wk. Low Ca-P led to a higher egg production, but only when COH and MWS were fed. BW at 89 wk was higher with CWS compared to COH and MWS. BW uniformity was better with COH compared to MWS at 51 wk and both CWS and MWS at 67 wk. Tibia characteristics were not clearly affected by treatment, although there was a feed form×Ca-P interaction on compression at 89 wk, where compression was lower with MWS and low vs. high Ca-P. Low Ca-P during rearing led to higher eggshell thickness, compared to high Ca-P at 45 wk of age, but breaking strength was lower with low vs. high Ca-P at 75 wk. Although eggshell quality was affected by Ca-P and there were some interactions with feed form at some ages, the effect was not consistent. There was no clear relationship between eggshell quality and tibia characteristics. It was concluded that feeding low Ca-P in combination with COH and MWS during the rearing period positively affects egg production during late lay. Also, dietary Ca-P levels, compared to commercial practice, can be lowered during rearing, as this will not affect eggshell quality and bone mineralization at later ages.

Short-Term Dietary Calcium Fortification Increases Fecal Saturated Fat Content and Reduces Serum Lipids in Men

The effect of dietary calcium on fecal fatty acid excretion and serum lipids was tested in a randomized, single-blind metabolic study in 13 healthy men with moderate hypercholesterolemia. A low calcium base diet containing 34% of energy from fat, 13% from saturated fatty acids, 240 mg cholesterol/d and 410 mg Ca/d was compared with a fortified version in which calcium citrate malate was added to orange juice, (550 mg) muffins (750 mg), and two tablets (500 mg) for a total calcium intake of 2200 mg/d. Fecal collections (72 h, d 8, 9, 10) and blood from fasting subjects for lipids and lipoproteins (d 9, 10, 11) were obtained. The percentage of dietary saturated fat excreted per day increased from 6 to 13% with calcium fortification. There was no change in fecal bile acid excretion. The high Ca diet significantly reduced total cholesterol 6% (5.99 to 5.66 mmol/L), LDL cholesterol 11% (4.13 to 3.67 mmol/L), and apolipoprotein B concentrations 7% when compared with the low Ca diet (P < 0.05). There was no change in HDL cholesterol or apolipoprotein A1 concentrations. Urinary calcium excretion increased from 146 to 230 mg/d when the high Ca diet was consumed. Calcium fortification was effective in lowering total and LDL cholesterol concentrations and may be an effective adjunct to cholesterol-lowering diet therapy.

Intestinal Calcium Absorption in Rats Is Stimulated by Dietary Lactulose and Other Resistant Sugars

Lactulose is a disaccharide analogue of lactose that is resistant to metabolism in the small intestine but not in the large intestine. The effects of lactulose and other sugars on intestinal Ca absorption were determined from the decrease in the 47Ca:47 Sc ratio between diet and feces after feeding male rats diets containing these sugars during a single night. Dietary lactulose was more potent than lactose in stimulating Ca absorption and was effective between 5 and 38 wk of age. The component sugars of lactulose, galactose and fructose, did not influence Ca absorption when provided together at concentrations equimolar to that of lactulose. The stimulation of Ca absorption by dietary lactulose increased as dietary Ca concentration was raised and was not influenced by prior injections of calcitriol. Lactulose must be present in the same meal as Ca to stimulate Ca absorption, but this stimulation was lost if the rats were fed lactulose continuously for 2 or 7 d prior to the test diet. Other sugars thought to be poorly absorbed in the small intestine (xylitol, lactobionate, arabinose, raffinose, pyroglutamate, sorbitol, gluconate and raftilose) stimulated Ca absorption to an identical extent as lactulose. Cecectomy did not influence the enhancement of Ca absorption by lactulose. These results indicate that sugars resistant to metabolism and absorption in the small intestine but not the large intestine stimulate Ca absorption in the small intestine.