Effect of zinc supplements on the intestinal absorption of calcium

Pharmacologic doses of zinc are widely used as zinc supplements. As calcium and zinc may compete for common absorption sites, a study was carried out on the effect of a pharmacologic dose of zinc on the intestinal absorption of calcium in adult males. The analyzed dietary zinc intake in the control studies was normal, averaging 14.6 mg/day. During the high zinc study, 140 mg zinc as the sulfate was added daily for time periods ranging from 17 to 71 days. The studies were carried out during both a low calcium intake averaging 230 mg/day and during a normal calcium intake of 800 mg/day. Calcium absorption studies were carried out during the normal and high zinc intake by using an oral tracer dose of Ca47 and determining plasma levels and urinary and fecal excretions of Ca47. The study has shown that, during zinc supplementation, the intestinal absorption of calcium was significantly lower during a low calcium intake than in the control study, 39.3% vs 61% respectively, p less than 0.001. However, during a normal calcium intake of 800 mg/day, the high zinc intake had no significant effect on the intestinal absorption of calcium. These studies have shown that the high zinc intake decreased the intestinal absorption of calcium during a low calcium intake but not during a normal calcium intake.     

Effect of zinc supplements on the intestinal absorption of calcium.

Pharmacologic doses of zinc are widely used as zinc supplements. As calcium and zinc may compete for common absorption sites, a study was carried out on the effect of a pharmacologic dose of zinc on the intestinal absorption of calcium in adult males. The analyzed dietary zinc intake in the control studies was normal, averaging 14.6 mg/day. During the high zinc study, 140 mg zinc as the sulfate was added daily for time periods ranging from 17 to 71 days. The studies were carried out during both a low calcium intake averaging 230 mg/day and during a normal calcium intake of 800 mg/day. Calcium absorption studies were carried out during the normal and high zinc intake by using an oral tracer dose of Ca47 and determining plasma levels and urinary and fecal excretions of Ca47. The study has shown that, during zinc supplementation, the intestinal absorption of calcium was significantly lower during a low calcium intake than in the control study, 39.3% vs 61% respectively, p less than 0.001. However, during a normal calcium intake of 800 mg/day, the high zinc intake had no significant effect on the intestinal absorption of calcium. These studies have shown that the high zinc intake decreased the intestinal absorption of calcium during a low calcium intake but not during a normal calcium intake.     

Are iron-folate supplements harmful?

Zinc absorption during pregnancy was measured before and 24 h after 2 wk of daily, oral, iron-folate supplements. Absorption was reduced 24 h after iron-folate, which suggests a mucosal rather than a luminal effect. Also, zinc absorption in 10 healthy volunteers was reduced by folate supplements alone. Therefore, routine iron and folate supplementation may both have deleterious effects on zinc metabolism, especially during pregnancy when iron-folate supplements are often prescribed despite adequate dietary intakes of iron and folate but not of zinc.     

Effects of habitual chitosan intake on bone mass,bone-related metabolic markers and duodenum CaBP D9K mRNA in ovariectomized SHRSP rats

We have demonstrated that the habitual intake of chitosan can decrease bone mass in ovariectomized (OVX) SHRSP rats fed a low-Ca diet (0.1%). In the present study, we examined both the etiology of bone loss induced by dietary chitosan and the preventive effect of vitamin C supplementation. Rats were OVX and maintained on one of the following diets for 6 wk: 10% cellulose (CE). 10% chitosan (CH) or 10% chitosan with sodium ascorbate (CHVC). CH caused a significant reduction in bone mineral density (BMD) and stiffness in femurs and the fourth lumbar vertebrae (L4). There was no significant difference in intestinal Ca absorption between CH and CE, whereas CH intake significantly reduced intestinal P absorption. The bone loss in CH rats was accompanied with an increase in urinary Ca excretion and a decrease in serum Ca as well as a significant increment In serum PTH and 1,25(OH)2D3. The vitamin D receptor and calcium binding protein D9K mRNAs were also significantly increased in the duodenum of CH rats. Vitamin C supplementation to CH caused an increase in the Ca and P contents of femurs as well as BMD of the L4, with a decrease in urinary Ca excretion. These results indicate that dietary chitosan with low Ca intake possibly induces the loss of bone mass by enhancing urinary Ca excretion rather than by inhibiting Ca absorption, and that vitamin C supplementation could prevent bone loss caused by chitosan through the increment of retained Ca followed by suppression of urinary Ca excretion.     

Effect of vitamin D and low dietary calcium on lead uptake and retention in rats

The effects of cholecalciferol (formerly vitamin D-3) supplementation and alterations in dietary calcium levels on intestinal 210Pb absorption and tissue uptake were studied in weanling female Sprague-Dawley rats. Rats were placed in one of three groups: 1) normal dietary calcium with normal cholecalciferol; 2) low dietary calcium with normal cholecalciferol; or 3) normal dietary calcium with cholecalciferol supplementation. Blood 210Pb levels were determined at 3, 6, 12 and 24 hours following the administration of either an oral or an IP dose of 210Pb. Femur and kidney 210Pb activities were subsequently determined for all animals 24 hours after the administration of 210Pb. Cholecalciferol supplementation resulted in increased net intestinal absorption of 210Pb with uptake into femurs and kidneys. The effect of cholecalciferol to increase tissue uptake of 210Pb was shown to be independent of the effect of cholecalciferol on the gastrointestinal absorption of lead. A lowering of dietary calcium was shown to increase lead absorption with uptake into femurs; however, this increased tissue uptake of lead was shown to be dependent upon increased intestinal lead absorption and was not a direct effect of the low calcium diet.     

Effect of magnesium on the intestinal absorption of calcium in man.

In view of the widespread use of magnesium (Mg) as a nutritional supplement, we investigated whether Mg would affect the absorption of calcium (Ca) as the intestinal absorption sites for Mg and Ca differ.

The intestinal absorption of Ca, using 47CaCl2 as the tracer, and metabolic balances of Ca, phosphorus (P) and Mg were determined in five adult males under strictly controlled dietary conditions in control studies and during Mg supplementation. Mg was given as magnesium oxide (MgO) in 10 studies during two Ca intakes: five studies during a low Ca intake of 241 mg/day and five studies during a normal Ca intake of 812 mg/day. Dietary Mg intake ranged from 241 to 264 mg/day in control studies. During Mg supplementation, the total Mg intake ranged from 789 to 826 mg/day.

There was no change of the intestinal Ca absorption during Mg supplementation during the two Ca intakes. The only change was the higher 1-hour 47Ca plasma level in the 47Ca absorption studies during the high Mg intake. Urinary Ca increased during Mg supplementation only during the low Ca intake, the Ca balance became more negative but this difference was not significant. There was also no change in Ca excretion or Ca balance during the high Mg intake at the normal Ca intake of 800 mg/day. P balance studies showed a slight decrease in urinary P and an increase in fecal P, but the P balances did not change. Mg balances were negative in control studies during the two Ca intakes. Supplemental Mg increased both urinary and fecal Mg excretion and the Mg balance became positive, but these differences were not significant.

The increased Mg intake of 826 mg did not affect intestinal Ca absorption determined with tracer doses of 47Ca during Ca intakes of 241 and 812 mg/day.     

Effects of two marine dietary supplements with high calcium content on calcium metabolism and biochemical marker of bone resorption

BACKGROUND/OBJECTIVE: Calcium is essential for the bone metabolism but daily calcium requirements are not met in a significant proportion of the population. Fortunately, oral calcium supplementation can help to meet these needs; however, the calcium bioavailability depends on the calcium sources. The calcium absorption and bioavailability of dietary supplements from marine sources are not known. The objectives of this study were to evaluate the effects of two marine dietary supplements with a high calcium content: a fishbone powder (Phoscalim) and a ray cartilage hydrolysate (Glycollagene), in comparison with milk, and a placebo (maltodextrin), on calcium metabolism and a biochemical marker of bone resorption, using the oral calcium tolerance test. SUBJECTS: Twenty male volunteers were randomized to eat 836 mg of calcium from different sources compared to maltodextrin during a Latin square study. Serum calcium concentrations and other parameters of the calcium metabolism, such as serum intact parathyroid hormone (iPTH) and serum C telopeptides (s-CTX), were measured after an acute oral calcium load based on the Pak protocol. RESULTS: An increase in serum-corrected calcium areas under the curve (AUC) occurred with Phoscalim and Glycollagene when compared to milk. Significantly lower iPTH concentrations were observed with Glycollagene than with milk at T0+1 h, T0+3 h, T0+6 h and with Phoscalim than with milk at T0+6 h. A significantly lower s-CTX concentration was observed with Glycollagene than with milk and Phoscalim at T0+6 h. Furthermore, the urinary calcium/creatinine ratio increased significantly more with Glycollagen than with milk in T0 h+3 h and T3 h+6 h. CONCLUSION: These two dietary supplements from marine sources constitute oral calcium sources when compared to milk on calcium absorption and bone resorption markers on short time.     

Spray-dried porcine plasma reduces the effects of staphylococcal enterotoxin B on glucose transport in rat intestine

We investigated the intestinal transport of D-glucose (D-Glc) and 3 essential amino acids in a model of intestinal inflammation, and the effects of dietary supplementation with animal plasma proteins on this function. Wistar Lewis rats were fed a diet containing an isonitrogenous amount of milk protein (control group) or a diet supplemented with either spray-dried animal plasma (SDAP) or immunoglobulin concentrate (IC) from porcine plasma, from d 21 of life (weaning) until d 35. On d 30 and 33, rats were challenged intraperitoneally with Staphylococcus aureus enterotoxin B (SEB; groups SEB, SEB-SDAP, and SEB-IC) and on d 35, brush border membrane vesicles (BBMVs) were prepared and used for transport and binding studies. Administration of SEB reduced D-Glc transport across sodium glucose transporter 1 [SGLT1; 20% reduction in maximal transport rate (Vmax); P < 0.05], without affecting the Michaelis constant (Km). The results from specific phlorizin binding, Western blot, and immunohistochemistry supported the view that the effects of SEB are due to reduced expression of D-Glc transporters in the apical membrane. SEB increased the passive diffusion constant (Kd) for D-Glc 3-fold (P < 0.05). SEB did not affect mediated or passive amino acid fluxes of L-leucine, L-methionine, or L-lysine. Dietary SDAP increased the D-Glc Vmax in the SEB group without affecting the passive component. Changes in d-Glc Vmax due to SEB and to the dietary treatments were correlated with changes in the number of SGLT1 transporters present in the BBMVs (r = 0.9468; P < 0.05). Dietary IC had no observed effect. We estimate that, in rats challenged with SEB, SDAP supplementation can increase glucose absorption by 8-9% during the interdigestive periods.     

Calcium supplementation: effect on iron absorption

The influence of calcium supplements on the absorption of dietary nonheme iron and of iron supplements was evaluated in 61 normal volunteer subjects by use of a double-radioisotope technique. When taken without food, calcium carbonate did not inhibit the absorption of ferrous sulphate with doses of either 300 mg Ca and 37 mg Fe or 600 mg Ca and 18 mg Fe. However, at the latter levels, calcium citrate and calcium phosphate reduced iron absorption significantly by 49% and 62%, respectively. All calcium supplements inhibited absorption of the iron supplement when taken with food. The absorption of dietary nonheme iron was also inhibited by all three supplements. This inhibition was less pronounced from a meal of high iron availability and low calcium content (28%) than from a breakfast meal of low iron availability and high calcium content (55%). These results suggest that taking regular calcium supplements with meals makes it more difficult for women to meet their daily iron requirement.     

High phosphorus intake only slightly affects serum minerals, urinary pyridinium crosslinks and renal function in young women

OBJECTIVE: Assessment of the physiological effects of a diet rich in phosphorus in young women. DESIGN: Control period I--commercial basic diet containing 1700 mg P and 1500 mg Ca/day for 4 weeks. Supplementation period--a 6 week high-phosphorus period of 3008 mg P and 1995 mg Ca/day. Control period II--4 weeks washout with basic diet as in period I. SETTING: Institute of Nutritional Science, Friedrich Schiller University, Jena. SUBJECTS: Ten healthy women, aged 20-30y. INTERVENTIONS: Orange juice and tablets, containing supplements of Ca5(PO4)3OH and NaH2PO4, totalling 1436 mg elemental phosphorus per day. RESULTS: There was an increase of 10.7+/-13.7 pg/ml in serum PTH, a decrease of 0.6+/-0.6 ng/ml in serum osteocalcin, an increase of 73.6+/-136.6 nmol/mmol creatinine in urinary pyridinoline and of 19.3+/-36.0 nmol/ mmol creatinine in urinary deoxypyridinoline, and a decrease of 2.6+/-9.3 mg/l in urinary microalbumin. All changes were insignificant. There were no changes in serum levels of Ca, PO4 or Zn, in serum concentration of 1,25-(OH)2D3, and in urinary beta-2-microglobulin excretion. Phosphorus supplementation caused intestinal distress, soft stools or mild diarrhoea. CONCLUSIONS: In spite of a high phosphorus supplementation no significant changes in bone-related hormones, pyridinium crosslinks as markers of bone resorption and parameters of renal function in young women were found.     

Calcium supplements and milk: effects on acid-base balance and on retention of calcium, magnesium, and phosphorus

The effect of supplementing a basal diet containing 697 mg calcium daily (17.4 mmol/d) with an additional 900 mg Ca daily from milk, Ca chloride, or a Ca carbonate preparation was examined in eight adult males during a 56-d metabolic balance study. The ingestion of the milk or Ca supplements had no overall effect on Ca retention by these subjects because the milk and supplements depressed apparent absorption of Ca in the gut and fractional tubular reabsorption of Ca in the kidneys. Supplementation of the diet with CaCl and to a lesser extent with milk significantly increased renal acid excretion whereas supplementation with CaCO3 depressed renal acid excretion. The three Ca supplements significantly altered magnesium and phosphorus absorption and urinary excretion in different manners but had no overall effect on retention of P or Mg. The responses of our subjects to these treatments may be different than those of subjects who are chronically in negative balance in regard to Ca.     

Enhancement of calcium absorption in rats by coadministration of glucose polymer

Glucose polymer derived from corn starch is widely used in infant formula and nutritional supplements as a readily digestible, low osmolarity source of calories. We have previously observed that glucose polymer causes a marked increase in intestinal calcium absorption in patients with intestinal malabsorption and in normal subjects. The present study investigates the effect of concurrently administered glucose polymer on intestinal 45calcium absorption in rats. The effect of glucose polymer on calcium absorption was compared to that of equivalent doses of dextrose or lactose. Femur radioactivity was determined as an index of calcium absorption. Carbohydrates were prepared at doses of 0.5, 2.0 and 4.0 mg/g body weight and administered with 45Ca by stomach gavage. Control rats received 45Ca in water alone. Coadministration of glucose polymer resulted in a dose-dependent increase in calcium absorption. At the highest dose of polymer studied calcium absorption was 75% greater than in control animals. Administration of lactose and dextrose also resulted in a dose-dependent increase in calcium absorption. Calcium absorption was 122 and 67% greater than controls when 4 mg/g BW lactose and dextrose were given with the 45Ca. We conclude that glucose polymer stimulates calcium absorption in rats similar to lactose and glucose. These results suggest that glucose polymer may be a useful therapeutic adjunct in patient groups in which there is a desire to increase intestinal calcium absorption.     

Higher calcium urinary loss induced by a calcium sulphate-rich mineral water intake than by milk in young women

It is well known that the intestinal availability of Ca from Ca-rich mineral waters is equivalent to that of milk Ca. However, the effect of associated anions on Ca urinary loss needs to be addressed. The aim of the current study was to compare, under ordinary conditions of consumption, milk and a SO4-rich mineral water as the Ca provider in a large number of subjects consuming the same quantity of Ca from the two sources in a crossover study lasting for an extended period. Thirty-seven healthy women completed a 12-week protocol, divided into four periods of 3 weeks (W). In the first (W1-3) and third (W6-9) periods, dietary Ca intake was restricted to 600 mg/d. In the second (W4-6) and final (W10-12) periods, either 400 ml/d medium-fat milk or 1 litre of a Ca- and SO4-rich mineral water, each providing about 480 mg Ca/d, was added to the diet in a random manner. Dietary evaluation, blood and urinary measures were performed during the last week (W6 and W12) of each Ca supplementation period. The urinary excretion of Ca was higher (0.5 mmol/d more) with water than with milk (P<0.001). An examination of all the dietary factors known to influence calciuria suggested that the acidogenic action of SO4 was responsible for this increased calciuria. Thus, despite an equal Ca intake and assuming an unchanged intestinal absorption, these results suggest that Ca balance is better with milk consumption than with CaSO4-rich water.     

Bovine colostrum supplementation does not affect nutrient absorptive capacity in healthy young men

Bovine colostrum (BC) contains bioactive components that have been shown to enhance gastrointestinal development and increase nutrient absorptive capacity in neonatal animals. Recent studies in adult humans have shown that BC increases lean body mass and improves exercise performance and a number of authors have suggested that BC may elicit these effects by enhancing intestinal nutrient absorption. The purpose of this study was to determine the effects of BC supplementation on plasma nutrient and/or insulin responses to a standard feed as a marker of intestinal absorptive capacity. Twelve healthy adult males consumed 60 g · day⁻¹ of either concentrated BC protein powder (n = 6) or concentrated whey protein (WP; n = 6) for eight weeks in a randomised, double-blind, placebo controlled, parallel design. Plasma alanine, glucose and insulin concentrations were measured in response to oral L-alanine (OATT) and oral D-glucose (OGTT) tolerance tests prior to and after 8 weeks of supplementation. There were no significant differences in the plasma alanine, glucose or insulin responses to the OATT or OGTT between groups at Week 0 (P > 0.29), and the 8 weeks of supplementation had no significant effect on the responses in either group (P > 0.29). Supplementation with BC does not affect the plasma nutrient or insulin response to a standard feed. Therefore, we would conclude that BC does not affect intestinal nutrient absorption in healthy adult humans.     

Coenzyme Q10 in health and disease

The literature concerning the importance of coenzyme Q10 in health and disease has been reviewed. Usual dietary intake together with normal in vivo synthesis seems to fulfil the demands for Q10 in healthy individuals. The importance of Q10 supplementation for general health has not been investigated in controlled experiments. The literature allows no firm conclusions about the significance of Q10 in physical activity. In different cardiovascular diseases, including cardiomyopathy, relatively low levels of Q10 in myocardial tissue have been reported. Positive clinical and haemodynamic effects of oral Q10 supplementation have been observed in double-blind trials, especially in chronic heart failure. These effects should be further examined. No important adverse effects have been reported from experiments using daily supplements of up to 200 mg Q10 for 6-12 months and 100 mg daily for up to 6 y.     

大米膳食补充以不同组成的氨基酸后对钙平衡的影响

<正> Conner和Sherman二氏观察到低钙水平时增加蛋白质摄入量可加快大鼠生长速度,同时增加其钙化作用速度。McCance等人观察到正常成人,当增加蛋白质摄入量时,可升高钙在肠道吸收的量,但随即于尿中排出。Desikachar等人报告了蛋白摄入量与蛋白质的质量对鼠钙磷平衡的影响,认为高蛋白膳食可提高钙磷的利用率,对磷的影响更为显     

Urinary calcium and magnesium excretion by women in response to short-term calcium supplementation

Two hundred sixteen women (34–69 years) participated in a clinical trial to study the short-term (14 days) effects of calcium supplementation (1000 mg extra calcium given as oyster shell calcium) on urinary calcium and magnesium excretion. Before supplementation the women consumed an average of 879 mg Ca/day in self-selected diets; during supplementation they consumed approximately 1915 mg Ca/day (diet and supplement). The women excreted significantly more calcium in the urine during the supplementation period than initially (114 vs. 149 mg Ca/day) but this increase accounted for only 3.4% of the supplemental calcium. Approximately 24% of the women did not respond to the calcium supplements; they excreted less or equal amounts of urinary calcium in response to calcium supplementation. Hypercalciuria (>250 mg Ca/day) was observed in 3% of the women prior to supplementation and 7% of the women during calcium supplementation. Calcium supplementation had no effect on urinary magnesium excretion.     

Presence of impaired intestinal calcium absorption in chronic hypovitaminosis D and its change after cholecalciferol supplementation: assessment by the calcium load test

Background: Hypovitaminosis D is common in Asian Indians and its functional significance is currently under investigation. Previous studies have reported on the effect of low serum 25(OH)D levels (<50 nmol L^?1) on bone mineral density and serum parathyroid hormone values. The present study assessed the effect of chronic hypovitaminosis D in Asian Indians on intestinal calcium absorption and its change after cholecalciferol supplementation. Methods: Subjects included 29 healthy volunteers [mean (SD) age, 28.4 ± 6.4 years] with low serum 25(OH)D levels on screening. Intestinal calcium absorption was assessed by the ‘calcium load test’ with 1 g of oral elemental calcium. Subjects were put on a calcium restricted diet 1 week prior to the test. The calcium load test was repeated in 26 of them after 8 weeks of supplementation with oral cholecalciferol (60 000 IU week^?1). Results: The mean urinary calcium/creatinine ratio of the study subjects was 0.027 ± 0.023 mg mg^?1 under fasting conditions and increased to 0.035 ± 0.032 mg mg^?1 after calcium loading (delta change = 29.6%, P = 0.33). After 8 weeks of cholecalciferol supplementation, the mean serum 25(OH)D increased from 18.9 ± 11.9 to 84.4 ± 34.9 nmol L^?1 (P < 0.0001). Concomitantly, the mean urinary calcium/creatinine ratio of the study subjects increased from 0.030 ± 0.024 mg mg^?1 under fasting conditions to 0.059 ± 0.045 mg mg^?1 after calcium loading (delta change = 96.6%, P = 0.008). Conclusions: The results obtained in the present study show that chronic hypovitaminosis D in Asian Indians has functional relevance in terms of its effect on intestinal calcium absorption, which improves with cholecalciferol supplementation. These findings support the need for improving the vitamin D status of Asian Indians through dietary supplementation and exposure to sunshine.     

Optimization of calcium intake for the prevention of osteoporosis and osteoporotic fractures: a review of the evidence

One of the main focuses of lifestyle modification for the prevention of osteoporosis and osteoporotic fractures in Japan is improvement in dietary calcium intake. However, virtually no randomized controlled trial to assess the preventive effects of administration of calcium on the risk of fractures has been conducted in Japan. In this study, we reviewed all the scientific papers currently available from medical literature databases to propose evidence-based recommendations on the preventive procedures for osteoporosis. The result of the present systematic review gives the evidence showing that calcium supplementation or optimal dietary calcium intake increases bone density in childhood and adolescence and reduces the risk of fracture due to osteoporosis in the elderly people regardless of the gender. The evidence also supports the current health policy guiding the elderly to increase their dietary calcium intake in daily life.     

Plasma changes in micronutrients following a multivitamin and mineral supplement in healthy adults

OBJECTIVE: To estimate the micronutrient (riboflavin, folate, vitamin C, vitamin B(12), iron, zinc and copper) bioavailability in healthy adults from a multi-micronutrient dietary supplement to assess the possible influence on it by the tablet disintegration properties and by the relative intestinal permeability of subject. METHODS: The bioavailability of seven micronutrients from a single brand of multi-micronutrient dietary supplement was measured on two separate occasions in the presence of a standardized test meal in 15 healthy adult subjects. Each subject visited the Metabolic Research Unit on four separate randomized occasions for an absorption test. One test measured the intestinal permeability. The other three tests measured the postprandial changes in plasma or serum concentrations after consuming a test meal alone (control:placebo effect), or the test meal with either whole or crushed and powdered dietary supplements. 15 healthy Caucasian adult volunteers, aged 42 +/- 14 years. RESULTS: The 12 hour-post-dose AUC for riboflavin, folate and vitamin C (whole and crushed tablet), and that for vitamin B(12) (only for the crushed tablet treatment) and iron (only for the whole tablet treatment) were all significantly (p < 0.001) higher than after a test meal alone. In contrast there was no significant increase in the AUC after supplement intake for zinc and copper. Neither the form of the supplement for all micronutrients tested nor intestinal permeability of the subject for riboflavin, folate, vitamin C, iron, zinc and copper influenced the postdose nutrient AUC. In contrast, for vitamin B(12) the intestinal permeability of the subject influenced significantly the nutrient AUC (p = 0.003). CONCLUSION: Tablet disintegration characteristics of this dietary supplement did not limit absorption of these seven micronutrients. The intestinal permeability of subject was only positively correlated with the B(12) bioavailability. Results are suggestive of using multi-micronutrients dietary supplements as a vehicle to decrease the prevalence of multiple micronutrient deficiencies overall for vitamins in healthy adults.