Influence Of Dietary Calcium Research Articles

Involvement of epigenetic mechanisms in regulating expression of the calcium sensing receptor in colorectal cancer

Involvement of epigenetic mechanisms in regulating expression of the calcium sensing receptor in colorectal cancer

The Influence of Dietary Calcium and Phosphorus Imbalance on Intestinal NaPi-IIb and Calbindin mRNA Expression and Tibia Parameters of Broilers.

A 2×2 factorial experiment was conducted to study the effect of dietary calcium and non-phytate phosphorus (nPP) imbalance on calbindin and NaPi-IIb mRNA levels in the small intestine and tibia parameters of broiler chicks. One hundred and forty four 1-d-old Arbor Acres male broiler chicks were divided into four treatments consisted of six replicates with six chicks each. The two dietary calcium levels were 1.10% and 0.60%, and two dietary nPP levels were 0.50% and 0.27%. Results showed that a high Ca/nPP ratio diet (4.07:1) significantly depressed feed intake and weight gain of broilers (p<0.05), but a lower Ca:nPP ratio (1.2:1) had no influence (p>0.05). Low-Ca with low-P diet resulted in low tibia minerals and tibia breaking strength of broilers, and all the tibia parameters were further decreased when the dietary ratio of Ca to P was relative higher. Low dietary Ca or P up-regulated the calbindin and NaPi-IIb mRNA expression levels. Low Ca with normal P diet up-regulated duodenal calbindin mRNA expression level to the greatest extent. Low P with a normal Ca diet significantly enhanced NaPi-IIb mRNA expression level to the highest extent. These results suggest that the calbindin and NaPi-IIb mRNA expression were enhanced by the imbalance between dietary Ca and nPP, and their expression were not only influenced by Ca or nPP level, but also the ratio of Ca:nPP.

Effect of high phosphorus diet on tooth microstructure of rodent incisors

Enamel hypoplasia and disruption of dentinogenesis are the most common abnormalities of development and mineralization of human teeth. Several reports are available in the literature on the influence of dietary calcium on the formation of human and rodent tooth; however, the information about the influence of dietary phosphorus on the tooth formation is scarce. The aim of the present investigation was to examine the chronic effect of high phosphorus diet and improper dietary calcium to phosphorus ratio on the mandibular incisor microstructure in a hystricomorph rodent--Octodon degu--using macroscopic observation, histopathological examination, transmission and scanning electron microscopy. The present study shows that enamel and dentin development is disturbed under high phosphorus diet and improper calcium to phosphorus ratio. Disturbed mineral metabolism resulted in enamel depigmentation, enamel hypoplasia, enamel pitting and altered dentin morphology. The results suggest that more attention should be focused on dietary phosphorus content when facing altered tooth structure in young patients with deciduous or permanent dentition. Furthermore, we showed that degus can be used as an experimental animal model for the study of the developmental teeth disturbances.

Meta-analysis of phosphorus utilisation by broilers receiving corn-soyabean meal diets: influence of dietary calcium and microbial phytase

Pollution relative to phosphorus excretion in poultry manure as well as the soaring prices of phosphate, a non-renewable resource, remain of major importance. Thus, a good understanding of bird response regarding dietary phosphorus (P) is a prerequisite to optimise the utilisation of this essential element in broiler diets. A database built from 15 experiments with 203 treatments was used to predict the response of 21-day-old broilers to dietary non-phytate P (NPP), taking into account the main factors of variation, calcium (Ca) and microbial phytase derived from Aspergillus niger, in terms of average daily feed intake (ADFI), average daily gain (ADG), gain to feed (G:F) and tibia ash concentration. All criteria evolve linearly (P < 0.001) and quadratically (P < 0.001) with dietary NPP concentration. Dietary Ca affected the intercept and linear component for ADG (P < 0.01), G:F (P < 0.05) and tibia ash concentration (P < 0.001), whereas for ADFI, it affected only the intercept (P < 0.01). Microbial phytase addition impacted on the intercept, the linear and the quadratic coefficient for ADFI (P < 0.01), ADG (P < 0.001) and G:F (P < 0.05), and on the intercept and the linear component (P < 0.001) for tibia ash concentration. An evaluation of these models was then performed on a database built from 28 experiments and 255 treatments that were not used to perform the models. Results showed that ADFI, ADG and Tibia ash concentration were predicted fairly well (slope and intercept did not deviate from 0 to 1, respectively), whereas this was not the case for G:F. The increase in dietary Ca concentration aggravated P deficiency for all criteria while phytase addition had a positive effect. The more P deficiency was marked, the more the bird response to ADFI, ADG, G:F and tibia ash concentration was exacerbated. It must also be considered that even if the decrease in dietary Ca may improve P utilisation, it could in turn become limiting for bone mineralisation. In conclusion, this meta-analysis provides ways to reduce dietary P in broiler diets without impairing performance, taking into account dietary Ca and microbial phytase.

Influence of dietary calcium and phosphorus supply on epithelial phosphate transport in preruminant goats

P homeostasis affected by high or low Ca and/or P supply in preruminant goats was characterized by balance studies in vivo. The main excretion pathway was the renal P(i) excretion whose extent was modulated by variations in dietary P and/or Ca supply. Faecal P excretion remained low irrespective of dietary regimen. The balance data were combined with respective in vitro data on P(i) transport properties and their adaptation in response to changes in dietary Ca and/or P intake. Therefore, P(i) transport capacities were determined by P(i) uptake into brush border membrane vesicles of jejunum and kidney. Epithelial P(i) transporters were determined semiquantitatively by northern and western blot analyses in jejunum, kidney and salivary gland. Renal P(i) transport was downregulated by doubling dietary P supply while doubling both, Ca and P as well as restrictive Ca at unchanged P led to slight, but not significant reductions in renal P(i) transport. Jejunal P(i) transport was reduced by P excess (doubling P and doubling both, Ca and P), but only NaPi IIb protein expression was significantly diminished. In conclusion, the significance of epithelial adaptation to dietary Ca and P supply for P homeostasis is discussed in preruminant goats.

Influence of dietary calcium and phytase on phytate phosphorus hydrolysis in broiler chickens

The effect of Ca and phytase on phytate phosphorus (PP) hydrolysis was studied in vitro and in vivo. In vitro, PP hydrolysis by a 3-phytase and a 6-phytase was studied at pH 2.5 and 6.5 with Ca added at levels equivalent to 0, 0.1, 0.2, 0.4, 0.7, or 0.9% of the diet. Irrespective of enzyme, Ca at a level as low as 0.1% reduced (P < 0.05) PP hydrolysis at pH 6.5. To test these effects in vivo, 22-d-old male broilers were fed 1 of 6 diets (10 replicate pens of 4 birds per diet) for 30 h. The experimental design was a 3 × 2 factorial arrangement of 3 phytase treatments (0, 500 U of phytase A/kg of diet, and 500 U of phytase B/kg of diet) and 2 added Ca levels (0 and 0.5% from CaCO3) to a corn-soy basal diet. Adding Ca to the diet resulted in a reduction (P < 0.05) in ileal PP disappearance from 69.2 to 25.4% when the 0 and 0.5% added Ca diets were fed, respectively, and in apparent ileal Ca and P absorption (46.3 to 33.6% and 67.9 to 29.4% when 0 and 0.5% Ca were added, respectively). Inclusion of a 3-phytase improved (P < 0.05) ileal PP disappearance from 25.4 to 58.9% in diets containing 0 and 0.5% added Ca, but the improvement was less pronounced with a 6-phytase. Apparent ileal Ca absorption was improved (P < 0.05) when Ca, phytase, or both were added to the diet.

Influence of dietary calcium and phosphorus content in a fixed ratio on growth and development in Great Danes.

To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor 1 and parathyroid hormone concentrations, radiography, and blood chemistry analysis results. 32 purebred Great Dane puppies from 4 litters. At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age. Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group. Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age.

Influence of Dietary Calcium on Subacute Lead Toxicity in the Rat

Influence of Dietary Calcium on Subacute Lead Toxicity in the Rat

Finding Consensus in the Dietary Calcium-Blood Pressure Debate

No single study or avenue of investigation can resolve the scientific controversies that entangle efforts to determine the effects of specific nutrients on medical conditions. To reach consensus in this area requires a substantial body of plausible, reproducible and consistent data from various investigative approaches—such as the data that now exist regarding the relationship between dietary calcium and blood pressure. In this paper we describe the plethora of epidemiological and clinical studies and analyses that have been published in the last two years and which cumulatively reveal the consistency of the available data regarding the influence of dietary calcium on blood pressure regulation. Nearly 20 years of investigation in this area has culminated in remarkable and compelling agreement in the data, confirming the need for and benefit of regular consumption of the recommended daily levels of dietary calcium.

Influence of dietary calcium and vitamin D on diet-induced epithelial cell hyperproliferation in mice.

Previous epidemiologic and laboratory studies, including some from our own laboratory, have suggested that a high-fat diet increases risk of cancer development in the pancreas, prostate, colon, and breast and that carcinogenesis in some of these organs may be influenced by alterations in dietary calcium and vitamin D. In this study, we sought to investigate the effect of added dietary calcium or vitamin D on the development of epithelial cell hyperproliferation induced by a Western-style diet in the exocrine pancreas, prostate, and mammary gland of mice. Four-week-old C57BL/6J mice were given either a control diet (American Institute of Nutrition [AIN]-76A), a Western-style diet (containing reduced calcium and vitamin D and the fat level of the average human Western diet), or a putative chemopreventive diet (a Western-style diet with the addition of dietary calcium and vitamin D). Nine weeks after dietary intervention, osmotic pumps were implanted in the mice to provide 3 days of bromodeoxyuridine (BrdU) infusion. All P values are two-sided. Mice on the Western-style diet had statistically significant increases in BrdU-labeling indices of epithelial cells in the interlobular (P = .015) and intralobular (P = .012) ducts and centroacinar cells (P = .001) of the pancreatic duct system, the dorsal lobe of the prostate (P = .045), and the terminal ducts of the mammary gland (P = .032), compared with mice in the respective control diet groups. Adding dietary calcium and vitamin D markedly suppressed the Western-style diet-induced hyperproliferation of epithelial cells in those tissues (P = .001-.033). This study confirms previous findings that a Western-style diet produces hyperproliferation of epithelial cells in several organs and that the changes can be prevented by increasing dietary calcium and vitamin D alone.

The Influence of Dietary Calcium and Protein on Third Cycle Hens Under Heat Stress

An experiment was conducted to evaluate the response of heat-stressed hens to increases in dietary calcium at two protein levels. Criteria evaluated included feed consumption, energy consumption, egg weight, egg production, egg specific gravity, and calcium and phosphorus solubilization and excretion. There were no effects of different calcium levels on egg production or egg weight. Increasing dietary calcium from 3.5% (2.9 g/hen/day) to 3.9% (3.2 g/hen/day) significantly increased egg specific gravity. Further increases in calcium intake however, did not improve egg shell quality. Protein level had no influence on egg production or egg specific gravity.

Influence of Dietary Calcium on Chlordecone-Induced Biochemical Changes in Serum of Rat

Male, Sprague-Dawley rats were treated with different (1, 10, 50, and 100 ppm) concentrations of chlordecone (Cd) in calcium-sufficient (Ca-S) or calcium-deficient (Ca-D) diet for 15 days. No significant changes in serum total proteins were observed. However, serum nonprotein nitrogen compounds (urea, uric acid, and creatinine) and glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, creatine kinase, and alkaline phosphatase were significantly increased at 50 and 100 ppm of Cd. Chlordecone induced more increase in these serum components of rats fed with Ca-D as compared to Ca-S diet. Increased serum nonprotein nitrogen compounds and enzymes indicate Cd-altered glomerular and hepatic functions.

Influence of Dietary Calcium and Vitamin D on Colon Epithelial Cell Proliferation and 1,2-Dimethylhydrazine-Induced Colon Carcinogenesis in Rats Fed High Fat Diets

We investigated whether increased levels of dietary calcium and vitamin D could inhibit colon carcinogenesis in rats injected with a single dose of 1,2-dimethylhydrazine. Rats were given a single subcutaneous injection (200 mg/kg body wt) 2 wk before they were fed purified diets containing 20% fat for 32 wk. Diets contained one of three levels of calcium (5, 10 or 15 g/kg diet) as calcium gluconate and one of three levels of vitamin D (0.025, 0.05 or 0.1 mg/kg diet) as cholecalciferol in a 3 x 3 factorial design. Rats receiving the highest level of vitamin D had greater plasma concentrations of 25-hydroxy-vitamin D. Autoradiographic examination of [3H]thymidine-treated rats demonstrated that a higher dietary level of calcium as well as higher levels of vitamin D significantly affected cellular kinetic indices. The total tumor incidence and tumor incidence in the distal colon was 45% lower in rats fed the highest level of both calcium and vitamin D compared with the other eight groups, although this decrease was not statistically significant (P = 0.12). The possible importance of these observations is discussed.

Calcium Metabolism in Great Dane Dogs Fed Diets with Various Calcium and Phosphorus Levels

The influence of dietary calcium on calcium metabolism was investigated in growing dogs that reach an adult body weight similar to that of humans. Seven groups of dogs (n greater than or equal to 5) were raised on a diet with a composition meeting the National Research Council (NRC) requirements (1974), but differing in calcium content, with or without a constant ratio to phosphorus. Control dogs fed 1.1% calcium and 0.9% phosphorus (all on a dry matter basis) were fed ad libitum (n = 10) or in restricted amounts (n = 6); dogs fed high calcium (3.3%) diets received either 0.9% phosphorus (n = 6) or 3.0% phosphorus (n = 6); dogs fed low calcium (0.55%) diets received either 0.9% phosphorus (n = 5 + 6) or 0.5% phosphorus (n = 8). Food intake, circulating total calcium and inorganic phosphorus concentrations and calcium metabolism, with 45Ca kinetics, were studied at 8, 14, 20 and 26 wk of age. Except for the difference in food intake in two groups at 14 wk (i.e., 0.55% calcium-0.9% phosphorus higher and 3.3% calcium-0.9% phosphorus lower, respectively, than the controls) no differences were noticed during the rest of the study. The mean plasma calcium concentrations did not differ between groups during the studies, whereas that of inorganic phosphorus revealed temporal aberrations in two groups. An absorption coefficient alpha of 45-66% was found for the control group. High and low calcium diets gave rise to values of 23-43% and 70-97%, respectively, for alpha irrespective of the phosphorus content of the diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of Dietary Calcium and Phosphorus on Urinary Calcium in Commercial Leghorn Hens

An experiment was conducted to determine the influence of dietary Ca (2, 4, and 6%) and P (.3 and .6% total) on urinary Ca and pH and on plasma Ca++ and inorganic P (Pi) in commercial Leghorn hens. Urine (six hens per treatment) or blood (eight hens per treatment) was collected from hens at 0, 7, 14, and 21 h postoviposition on Days 3 and 10 after its introduction to treatment diets.Low dietary P reduced (P≤.05) plasma Pi concentrations. The lowest concentration of dietary Ca reduced (P≤.05) plasma Ca++. Urinary pH and Ca were lowest at 14h after oviposition. Increasing dietary Ca from 4 to 6% had no influence on urinary Ca excretion when file diet contained .6% P. However, when the diet contained 4% Ca, lowering dietary P (from .6% to .3%) increased urinary Ca significantly. Increasing dietary Ca to 6% in the presence of low dietary P further elevated urinary Ca. Urine was acidic with all diets except with that containing 6% Ca and .3% P at 14h after oviposition. Results indicate that low dietary P has a greater influence on elevating urinary Ca in laying hens man excess dietary Ca.

Calcium Attenuates Cardiovascular Reactivity to Sodium and Stress in Blacks

The roles of dietary and behavioral factors in the etiology of hypertension are not well understood. Vulnerability to hypertension is thought to be affected by a complex interaction of nutritional, genetic, neurophysiological, and psychosocial influences. We studied cardiovascular reactivity to sodium and stress in a group of 29 normotensive young men who were vulnerable to hypertension by virtue of familial and/or racial factors. Subjects with positive and negative parental histories of hypertension were provided all meals for five days during which blood pressure was monitored before each meal. Two groups were given 300 mEq/day dietary sodium with either 1100 mg/day or 410 mg/day dietary calcium. A third group consumed a 10mEq sodium diet with low dietary calcium. On the fifth day of the diet all subjects were tested for cardiovascular reactivity using a modified Stroop test as a mentally challenging task. Adaptation of systolic blood pressure (SBP) from the first to the fifth breakfast was most pronounced in subjects consuming high calcium with high sodium. Perseveration of SBP reactivity to repeated mental challenge was found in subjects who consumed high sodium with low calcium and in subjects with positive parental histories of hypertension. The perseverative phenomenon was particularly well-defined in subjects who had the highest urinary excretion of calcium. Our findings suggest a prophylactic influence of dietary calcium and its retention on cardiovascular reactivity to sodium and stress. We also elucidate a theoretical proposition concerning the role of neurophysiological inhibitory capacity in the transition from normotension to the chronic dysregulatory state of essential hypertension.

Influence of Dietary Calcium and Cholecalciferol on Composition of Plasma Lipids in Young Pigs

Young growing pigs were fed diets containing either 1 or 3 times the daily requirement of calcium and 1, 5 or 25 times the daily requirement of vitamin D (as cholecalciferol) in a completely randomized design with treatments in a 2 X 3 factorial arrangement. Excess dietary calcium increased the phospholipid concentration in the plasma, but not its partitioning among plasma lipoproteins. The level of dietary calcium had no effect on cholesterol, triacylglycerol or protein concentrations in plasma or their partitioning among plasma lipoproteins. Excess dietary calcium decreased body weight gains of pigs. The level of dietary cholecalciferol had no effect on body weight gain or on the concentrations of cholesterol, phospholipid, triacylglycerol or protein in plasma, or on their partitioning among plasma lipoproteins. Increased vitamin D intake resulted in increased plasma 25-hydroxycholecalciferol, whereas high dietary calcium decreased concentrations of 1,25-dihydroxy-vitamin D. Increased dietary calcium also increased plasma calcium concentrations of only plasma phospholipids and decreased growth rate, whereas excess dietary vitamin D had no effect on growth or lipid composition of plasma in growing pigs.

Blood pressure and hypothalamic norepinephrine and dopamine in calcium-deficient rats.

The influence of dietary calcium (Ca) on systolic blood pressure (BP) and hypothalamic norepinephrine (NE), dopamine (DA) and DA metabolites dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) concentrations was investigated in male Sprague-Dawley rats raised on diets containing 0.005, 0.17, 1.4, and 2.8% Ca for eight weeks starting at four weeks of age. Blood pressure was significantly higher in the 0.005% Ca and lower in the 2.8% Ca group respectively, compared with the control (1.4% Ca) group. Hypothalamic NE and DA were lower only in the 0.005% Ca group. DOPAC concentration was higher in both Ca-deficient and -excess groups. No change in HVA was observed in any group. Plasma Ca was reduced and parathyroid hormone (PTH) was increased in Ca-deficient groups, but plasma Ca and PTH were increased and decreased, respectively, (nondetectable) in the Ca-excess group. These results suggest that changes in BP due to altered dietary Ca metabolism may be due in part to altered adrenergic system, as well as to dietary-induced changes in calcium metabolism.

Report on placental and fetal physiology, a designated session of physiological society, Manchester, UK, April 1988

Compensatory renal growth: modulation by calcium and 1,25-(OH)2D3. To further elucidate the mechanisms by which compensatory renal growth (CRG) can be influenced by calcium and calcium regulating hormones, the influence of dietary calcium and phosphorus, parathyroid hormone (PTH) or 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was evaluated in unilaterally nephrectomized (UNI-NX) rats. These animals were sacrificed three days after UNI-NX and CRG of the remaining kidney was assessed by kidney wt, RNA and DNA gains, and by 3H-thymidine incorporation. The degree of CRG was enhanced in animals given a low dietary calcium and, conversely, was decreased in those receiving a phosphorus–poor diet. In thyroparathyroidectomized (TPTX) rats, PTH administration resulted in a dose proportional stimulation of CRG. When 1,25-(OH)2D3 was given to vitamin D deficient animals, the degree of CRG was enhanced in a dose proportional manner. In another experiment, TPTX-vitamin D deficient rats were given the same amount of 1,25-(OH)2D3 by miniosmotic pump infusion. In these animals, dietary calcium restriction, instead of stimulating, inhibited CRG. From these observations we conclude that calcium and calcium regulating hormones modulate CRG, and hypothesize that the effects observed are mediated through changes in cell calcium.

Influence of Dietary Calcium:Phosphorus Ratio on Mineral Excretion and Nephrocalcinosis in Female Rats

The effects of dietary calcium (Ca) concentration and calcium: phosphorus (Ca:P) ratio on mineral balance and nephrocalcinosis were studied in female rats. In the first experiment there were two dietary Ca concentrations (0.25 and 0.50%, wt/wt) at two different Ca:P ratios (0.6 and 1.3). In the second experiment the diets were formulated to contain 0.40% P and either 0.13, 0.25, 0.50 or 0.75% Ca. The diets contained 0.03% magnesium (Mg). The fecal outputs of Ca, P and Mg were lower (P less than 0.01) after feeding low Ca diets than after feeding high Ca diets. Urinary excretion of P decreased with increasing dietary Ca and increased with increasing P intake. In rats fed the 0.25% Ca diets whole-body retentions of Ca and P were lower than in the rats fed 0.50% Ca. Both increases in dietary Ca from 0.13 to 0.50% and P from 0.20 to 0.40% elevated Ca and P content of kidneys as well as the degree of nephrocalcinosis. However, after feeding the highest Ca concentration (0.75%) nephrocalcinosis was essentially absent while kidney concentrations of Ca and P were relatively low. When compared with 0.50% Ca in the diet, 0.75% Ca increased group mean whole-body retention of Ca but lowered that of P. In individual rats the degree of nephrocalcinosis and the concentrations of minerals in kidney were positively correlated.