Bioavailability of iron in cooked egg yolk for maintenance of hemoglobin levels in growing rats

The relative biological value (RBV) of iron in egg yolk was compared with that of iron in ferrous sulfate in prophylactic assays with weanling rats. Egg yolk cooked by one of three different methods was used in each experiment: (1) yolk of eggs boiled in the shell, lyophilized, and mixed with other dry diet ingredients; (2) pasteurized yolk and other diet components steamed with 8 liters of water per kilogram of diet; and (3) pasteurized yolk and other diet ingredients baked with 0.5 liters of water per kilogram of diet. Diets containing three levels of egg yolk and four levels of ferrous sulfate were fed to different groups of rats for 1, 2, and 3 weeks. Response of dietary iron was calculated as the regression of hemoglobin iron gain on iron intake and the nutritional quality of egg iron relative to that of ferrous sulfate iron was evaluated by slope-ratio analysis. RBV was 61, 64, and 90%, respectively, for iron of egg yolk cooked by the three methods. The presence of ascorbic acid during heat treatment of the diets significantly increased RBV of yolk iron from 64 to 92% in experiment 2, and increased it to a value equivalent to that of ferrous sulfate in experiment 3.     

Influence of dietary chloride on fluoride bioavailability in the rat

A factorial experiment was conducted with weanling rats fed a purified diet to determine the influence of dietary chloride (0.02, 0.10 and 0.50%) as sodium chloride on fluoride bioavailability (2 or 10 ppm as sodium fluoride). After 6 wk, rats fed the lowest chloride-containing diets had significant reductions of plasma chloride, urinary chloride excretion and growth rate compared to other chloride groups. Depressed growth occurred in rats fed chloride-deficient diets despite the fact that food intake was similar for all treatments. Fluoride retention was greatest in chloride-deficient rats, which was reflected in enhanced skeletal uptake of fluoride. Fluoride absorption was not inhibited by high chloride intake. We therefore conclude that emphasis on the effect of chloride on fluoride bioavailability should be directed towards an enhancement of fluoride retention by low salt (sodium chloride) diets rather than in terms of a possible negative effect of a high salt diet on fluoride absorption.     

Effects of dietary corn on hematological response of anemic rats to ferrous sulfate

Anemic rats were fed diets containing adequate quantities of all required nutrients, except iron, which was supplied by ferrous sulfate and/or corn grain. Diets were supplemented with the inorganic salt and corn in such a pattern that regression of hematological response on increments of ferrous sulfate intake could be calculated for 0, 25%, 50% and 75% dietary corn. Corn was added to the diets at the expense of starch which served only as a source of energy. Slopes of the regression lines for response (hemoglobin iron gain or final hemoglobin concentration) to ferrous sulfate intake were not altered significantly by inclusion of up to 75% corn in the diets. Results indicate that corn does not contain an inhibitor of iron absorption. Poor iron absorption from diets or meals in which corn provides a significant portion of the total food supply is probably due to a nutritional inadequacy of the corn, possibly its amino acid imbalance.     

Effects of dietary methionine, cystine and potassium sulfate on serum cholesterol and urinary ascorbic acid in rats fed PCB

Liver weight, liver and urinary ascorbic acid levels and serum cholesterol concentration were higher in rats fed polychlorinated biphenyls (PCB) than in controls. The influences of methionine, cystine and potassium sulfate on these metabolic responses were studied. Methionine or equivalent moles of cystine or potassium sulfate were added to a basal diet containing 10% soy protein isolate. The basal diet contained 0.3% of total sulfur-containing amino acids (S-AAs). When methionine was added to the basal diet, maximum gain in body weight was obtained with 0.5% of dietary S-AAs, while the highest values in serum cholesterol and urinary ascorbic acid were obtained with 0.8% of dietary S-AAs in rats fed PCB. Dietary addition of cystine had little effect on body weight gain. Nevertheless, in rat fed PCB, urinary ascorbic acid and serum cholesterol were significantly higher in rats fed the cystine-supplemented diet than in those fed the unsupplemented diet. Addition of potassium sulfate had no effect on body weight gain, urinary ascorbic acid or serum cholesterol. These results suggest that more S-AAs are required for the highest metabolic response to PCB than for maximum growth, and the higher requirement for S-AAs cannot be replaced by inorganic sulfate.     

抗贫血胶囊改善缺铁性贫血效果的初步观察

目的:观察抗贫血胶囊改善缺铁性贫血的效果。方法:选用150 g左右的雄性SD大鼠,用低铁饲料喂养法制备缺铁性贫血模型后,将大鼠随机分为5组,一组为对照组,一组为硫酸亚铁组(补充铁20.0 mg/kg),其余为高、中、低剂量血红素铁组,分别补充2.7、5.41、6.0 mg/kg的血红素铁。分别于补充前、补充35 d后,测定各组大鼠体重、血液学指标、血清铁、铁蛋白、红细胞游离原卟啉水平。结果:补铁前后,大鼠体重均有所增长,但各组之间均无显著差异。补充硫酸亚铁、抗贫血胶囊后,硫酸亚铁组和低、中、高剂量血红素铁组大鼠血红蛋白、红细胞计数、红细胞压积均明显高于对照组。硫酸亚铁组和低、中、高剂量血红素铁组大鼠红细胞游离原卟啉均明显低于对照组,硫酸亚铁组和中、高剂量血红素铁组大鼠的血清铁水平,中、高剂量血红素铁组大鼠血清铁蛋白明显高于对照组。结论:抗贫血胶囊有改善缺铁性贫血的作用。     

Calcium, magnesium and phosphorus utilization by rats fed sodium and potassium salts of various inorganic anions

We hypothesized that urinary excretion of calcium would be affected by both urinary excretion of acid and of total fixed anions. Calcium, magnesium and phosphorus utilization was examined in rats fed semipurified diets supplemented with approximately 0.4 mol sodium/kg diet or approximately 0.4 mol potassium/kg diet as chloride, sulfate, bisulfate, carbonate or bicarbonate salts in two studies. The ingestion of supplemental fixed anions (chloride, sulfate or bisulfate) increased urinary excretion of calcium, magnesium and phosphorus. It made no difference whether the anions were ingested as sodium or potassium salts. In Study 1, 80% of the variation in urinary calcium excretion could be explained on the basis of urinary excretion of sulfate, ammonia and total anions. In Study 2, 77% of the variation in urinary calcium excretion could be predicted on the basis of urinary excretion of total anions and sulfate. Although bone and plasma calcium concentrations were not responsive to these dietary changes, less magnesium was retained in bones of rats fed any of the supplemental salts.     

Chloride and phosphate as impediments to silica urinary calculi in rats fed tetraethylorthosilicate

Rats fed a dextrose-casein type of diet adequate for normal growth and containing 2% of tetraethylorthosilicate (TES) were used to study the effect of NaCl and Na2SO4 drinking waters, and dietary additions of chloride, sulfate and phosphate on formation of silica urinary calculi. In experiment 1, rats fed the basal-TES diet had a 53% incidence of silica urinary calculi. NaCl or Na2SO4 (0.07 N) drinking waters each increased (P less than 0.01) water intake and urine volume, whereas only NaCl reduced (P less than 0.05) the incidence of silica urinary calculi. The incidence of calculi in the rats treated with NaCl and Na2SO4 was 15 and 55%, respectively. The saline waters had similar effects on urine pH, silica, phosphorus, magnesium and calcium, as well as blood plasma magnesium and calcium. Plasma phosphorus tended to be higher (P = 0.08) in the NaCl-treated rats. In experiment 2, 50% of rats fed the basal-TES diet developed silica urinary calculi. Addition of 0.2 eq/kg diet of chloride, sulfate or phosphate as sodium salts (phosphate was an equal molar mixture of mono- and dibasic sodium phosphates) resulted in a reduction in silica urinary calculi (P less than 0.05) by dietary chloride (15% incidence) and phosphate (5% incidence) but not by sulfate (35% incidence). Water intake and urine volumes did not differ, urine calcium was increased (P less than 0.05) by sulfate, and urine phosphorus was increased (P less than 0.05) by phosphate. Blood plasma concentrations of calcium and magnesium did not differ, but plasma phosphorus was higher for animals fed the additional phosphate (P less than 0.1) or chloride (P less than 0.05) in the 2% TES diet.     

Effects of dietary magnesium and nickel on growth and bone characteristics in rats.

We examined the interaction of dietary magnesium (Mg) and nickel (Ni) on growth and, in particular, the size, composition and mechanical properties of bones in weanling rats. Male rats were fed a diet with 0.3, 1.0 or 2.0 times the recommended concentration of Mg and adequate amounts of other nutrients. After a week, groups fed the low- and high-Mg diets were subdivided and fed the same concentration of Mg plus 0 or 500 mg Ni/kg diet (from Ni chloride) for the remaining 7 weeks. Rats fed low Mg with added Ni grew slowly and had smaller femurs and vertebrae that contained less ash and withstood less force before breaking or compression than did bones of rats fed the low-Mg diet without Ni. However, the breaking stress calculated for femurs from Mg-depleted, Ni-supplemented animals was increased. Ni did not produce these effects when added to a diet high in Mg. Compared with high dietary concentrations, the low-Mg intake had little effect unless Ni was added.     

Enhancement of fluoride retention by low dietary chloride without manifestation of chloride deficiency in the rat

Weanling male albino rats were fed a purified diet containing 10 ppm fluoride as sodium fluoride and 0.02, 0.04, 0.06, 0.08, or 0.10% chloride as sodium chloride for 6 wk. Food intake was unaffected by the level of dietary chloride. Rats fed diets containing either 0.02 or 0.04% chloride had significantly higher fluoride retention and skeletal uptake of fluoride than did rats fed higher chloride levels. Diets, however, had to contain 0.04% chloride or more to support normal weight gain, femur ash weight and plasma chloride concentration. The ability to enhance fluoride content of bone on a low chloride diet without undesirable effects of chloride deficiency may have important implications, since fluoride is thought to play a role in strengthening the mineral apatite structure of bone.     

Effects of dietary magnesium and nickel on growth and bone characteristics in rats.

We examined the interaction of dietary magnesium (Mg) and nickel (Ni) on growth and, in particular, the size, composition and mechanical properties of bones in weanling rats. Male rats were fed a diet with 0.3, 1.0 or 2.0 times the recommended concentration of Mg and adequate amounts of other nutrients. After a week, groups fed the low- and high-Mg diets were subdivided and fed the same concentration of Mg plus 0 or 500 mg Ni/kg diet (from Ni chloride) for the remaining 7 weeks. Rats fed low Mg with added Ni grew slowly and had smaller femurs and vertebrae that contained less ash and withstood less force before breaking or compression than did bones of rats fed the low-Mg diet without Ni. However, the breaking stress calculated for femurs from Mg-depleted, Ni-supplemented animals was increased. Ni did not produce these effects when added to a diet high in Mg. Compared with high dietary concentrations, the low-Mg intake had little effect unless Ni was added.     

Utilization of zinc from picolinic or citric acid complexes in relation to dietary protein source in rats

Young male Sprague-Dawley rats were divided in 18 groups of eight animals each and were fed ad libitum for 24 d a purified diet with 20% casein, whey protein or serum albumin as protein source. Each diet was supplemented with zinc picolinate, zinc citrate or zinc sulfate to a level of dietary zinc equal to 5 or 10 ppm. The source of zinc had no significant effect on zinc utilization with any of the three dietary proteins or at either dietary zinc concentration. With the 5 ppm Zn diet zinc concentration in the serum, but not weight gain or the zinc concentration in femur, testis or whole body was lower in rats fed the casein diet than in those fed the whey diet. Zinc concentrations in serum, femur, testis and whole body, but not weight gain, were lower in rats fed the casein diet than in those fed the serum albumin diet. With the 10 ppm Zn diet, zinc concentrations in serum, femur and whole body, but not weight gain nor zinc concentration in testis, were lower in rats fed the casein diet than in those fed either of the other diets. These results suggest that the reason for the lower utilization of zinc from cow milk in comparison to human milk may be the higher casein concentration in cow milk.     

Triiodothyronine (T3) and thyroxine (T4) levels in iron-deficient,hypertriglyceridemic rats

Two experiments were conducted to examine the role and status of thyroid hormone in iron-deficient hypertriglyceridemic rats. In Experiment I, male weanling rats were fed 6 diets containing 2 levels of dietary iron [6 ppm(?Fe) and 240 ppm(+Fe)] and 3 combinations of fats [14% beef tallow +1% safflower oil(B), 7.5% beef tallow +7.5% safflower oil(BS) and 15% safflower(S)]. After 3 weeks, rats receiving ?Fe diets had elevated triglyceride (TG) and depressed triiodothyronine(T3) and thyroxine (T4) levels in serum, regardless of the fat source. No difference in the post-heparin lipolytic activity could be detected after 6 weeks of dietary treatment between rats fed +Fe and ?Fe diets. Feeding the BS+Fe diet to the BS?Fe rats for 1 week brought their serum TG, T3, and T4 to levels similar to those of rats fed the BS+Fe diet for 7 weeks. In Experiment II, male weanling rats were fed B diets containing 6 levels of dietary iron (3, 6, 10, 15, 30, and 60 ppm) for 4 weeks. Weekly determinations of packed cell volume(PCV), serum T3, T4, and TG were made. PCV, serum T3 and T4 levels increased as dietary iron content increased. The relationship between serum TG level with dietary iron level or PCV was quadratic, curvilinear. Data also suggest that part of the iron effect on serum TG level is thyroid hormone related.     

Bioavailability to rats of iron and zinc in wheat bran: response to low-phytate bran and effect of the phytate/zinc molar ratio

Low-phytate wheat bran was produced by enzymatic hydrolysis and extraction. Rat bioassay methods were utilized to determine bioavailability of iron and zinc in the low-phytate brans and to study the effect of dietary phytate/zinc molar ratio on zinc bioavailability when the phytate source was bran. Endogenous phytase activity hydrolyzed 80-100% of the phytate when wheat bran was incubated in water overnight. The relative biological values of the iron in raw bran and phytate-free bran were 98 and 113, respectively, compared to 100 for ferrous ammonium sulfate in a hemoglobin repletion assay. Low-phytate brans with phytate/zinc molar ratios of 8 or less were equivalent to zinc sulfate as dietary sources of zinc for growth of rats. Rats fed diets that contained wheat bran with zinc sulfate added to reduce the dietary phytate/zinc molar ratio from 40 or 50 to 20 grew at the same rate as rats fed a phytate-free diet, but femur zinc values were lower than those in the reference group. Gel filtration chromatography of extracts of raw and low-phytate brans suggested that zinc might be associated with phytate in wheat bran.     

Calcium,sodium and choloride interactions in rats

In three studies the effects of changes in dietary sodium, chloride and calcium levels on urinary excretion and tissue levels of sodium, potassium, calcium, phosphorus and magnesium were evaluated. When rats were fed moderate (5000 μg Ca/g) levels of calcium, the addition of 4600–6300 μg Na/g to the basal diet as sodium chloride or sodium bicarbonate increased urinary volume. However, when rats were fed high (10,000 μg Ca/g) levels of calcium, only the addition of sodium chloride increased urinary volume. Rats fed excess sodium excreted more sodium in the urine. However, rats fed excess sodium as sodium chloride tended to excrete more sodium, potassium, calcium, phosphorus and magnesium in urine than rats fed equal amounts of sodium as sodium bicarbonate. Despite the many effects of the dietary treatments on urinary excretion, they had no effects on bone, muscle or kidney levels of sodium, potassium and phosphorus; on bone or muscle levels of calcium; or on muscle and kidney levels of magnesium. The effects of the treatments on bone magnesium levels were not consistent among studies.     

Effects of kimchi supplementation on blood pressure and cardiac hypertrophy with varying sodium content in spontaneously hypertensive rats

We tested the effects of dietary intake of freeze-dried Korean traditional fermented cabbage (generally known as kimchi) with varying amounts of sodium on blood pressure and cardiac hypertrophy in spontaneously hypertensive rats (SHRs). Wistar-Kyoto rats (WKY), as a control group, received a regular AIN-76 diet, and the SHRs were divided into four groups. The SHR group was fed a regular diet without kimchi supplementation, the SHR-L group was fed the regular diet supplemented with low sodium kimchi containing 1.4% salt by wet weight, which was provided in a freeze-dried form, the SHR-M group was supplemented with medium levels of sodium kimchi containing 2.4% salt, and the SHR-H group was supplemented with high sodium kimchi containing 3.0% salt. Blood pressure was measured over 6 weeks, and cardiac hypertrophy was examined by measuring heart and left ventricle weights and cardiac histology. SHRs showed higher blood pressure compared to that in WKY rats, which was further elevated by consuming high sodium containing kimchi but was not influenced by supplementing with low sodium kimchi. None of the SHR groups showed significant differences in cardiac and left ventricular mass or cardiomyocyte size. Levels of serum biochemical parameters, including blood urea nitrogen, creatinine, glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, sodium, and potassium were not different among the groups. Elevations in serum levels of aldosterone in SHR rats decreased in the low sodium kimchi group. These results suggest that consuming low sodium kimchi may not adversely affect blood pressure and cardiac function even under a hypertensive condition.     

Effect of increased dietary calcium on the development of reduced renal mass saline hypertension in rats

A diet fortified with calcium carbonate has been reported to reduce blood pressure in low-renin and salt-sensitive hypertensive patients. We have therefore examined the effect of increased dietary calcium on the development of reduced renal mass-saline hypertension in rats, a classical, low-renin, volume, and sodium-dependent model of hypertension. Rats with 70-75% reduction in renal mass were divided into experimental and control groups. The experimental rats were fed a sodium-free diet supplemented with calcium carbonate (2.0% calcium) and drank 1% saline for 5 weeks. Control rats consumed the salt-free diet and drank 1% saline for the same period. In control rats, as previously observed, blood pressure progressive increased from a control value of 120.0 +/- 1.2 to 174.2 +/- 1.2 mm Hg by the fifth week. In contrast, in the calcium-supplemented rats the development of hypertension was significantly attenuated; the blood pressure only increased from 117.0 +/- 1.2 to 134.0 +/- 3.8 mm Hg by the fifth week. This was associated with a 30% decrease in saline intake by the fifth week, with proportionate decreases in urine volume and sodium excretion but not potassium excretion. Urinary magnesium excretion increased. No such changes were seen in control rats. At the end of the treatment period, plasma levels of sodium, potassium, calcium, creatinine, BUN, and protein were not different, but plasma chloride and magnesium were lower in experimental rats; vascular smooth muscle cell membrane potentials were also not different. These data show that dietary calcium carbonate can attenuate the development of reduced renal mass-saline hypertension in the rat, possibly in part by altering sodium and water intake.     

Bioavailability of microencapsulated ferrous sulfate in powdered milk produced from fortified fluid milk: a prophylactic study in rats

OBJECTIVE: We investigated the iron bioavailability of microencapsulated ferrous sulfate (SFE-171) in a diet based on powdered milk by using the prophylactic method in rats. METHODS: The SFE-171 was added into fluid milk and industrially processed into powdered milk, which was then mixed in our laboratory with a normalized diet (17.2 +/- 2.1 mg Fe/kg). A reference standard diet using ferrous sulfate as iron-fortifying source (19.8 p+/- 2.9 mg Fe/kg) and a control diet without added iron (4.6 +/- 0.8 mg Fe/kg) were prepared in the laboratory in a similar way. These diets were administered to different groups of weaning rats for 28 d as the only solid nourishment. The iron bioavailability of the different sources was calculated as the relation between the mass of iron incorporated into hemoglobin during the treatment and the total iron intake per animal. RESULTS: The iron bioavailability values of SFE-171 and ferrous sulfate in the fortified diets were 41.6 +/- 6.6% and 42.6 +/- 4.2%, respectively; these results were significantly higher (P < 0.01) than the iron bioavailability of the control diet (28.8 +/- 8.1%). CONCLUSION: These results showed that iron-fortified powdered milk can be produced from fluid milk fortified with SFE-171. The bioavailability of SFE-171 in this rat model was not altered by the manufacturing process.     

Optimal protein level is required for normalization of taste sensitivity in rats

The influence of levels of dietary protein on taste sensitivity for sodium chloride and zinc status was studied in rats. Animals were given free access to one of seven graded levels of purified egg protein (PEP) diets for 28 days. Preference tests for the solution of sodium chloride (0.86 and 8.56 mmol/L) versus deionized water were conducted on days 19 and 21. Feces, urine and blood were collected for assay of zinc concentrations. Only the rats fed the 8% PEP diet discriminated low concentration of 0.86 mmol/L sodium chloride solution. The rats fed another diets discriminated only high concentration of 8.56 mmol/L sodium chloride solution. Twenty percent PEP diet-fed group did not discriminate both concentrations of sodium chloride. Zinc in serum concentration (r=0.89, p<0.001) and balance (r=0.78, p<0.001) was correlated with dietary protein intake. Serum zinc concentrations of the rats fed the 8 and 10% PEP diets were within the normal range. Retained zinc levels remained constant within the range of 4–8% PEP diets. The present study indicates that 8% PEP is optimal dietary protein level to normalize taste sensitivity for sodium chloride.     

Lack of Dietary Calcium Effect on Chlordecone Increased White Blood Cell Count, Total Iron, and Iron-Binding Capacity in Serum of Rat

Male Sprague–Dawley rats were treated with 0, 1, 10, 50, and 100 ppm of chlordecone (Cd) mixed in calcium-sufficient (Ca-S) or calcium-deficient (Ca-D) diet for 15 days. The control rats fed with Ca-D diet exhibited a significant increase in white blood cell (WBC) counts compared to the rats fed with Ca-S diet. Dietary calcium (Ca), however, did not elicit any significant effect on total iron content and iron-binding capacity (transferrin) of control rats, whereas Cd at higher concentrations significantly increased WBC counts, total iron, and iron-binding capacity in serum of both Ca-S and Ca-D rats. The data suggest that dietary Ca did not alter Cd-increased WBC count, total iron, and iron-binding capacity in serum of rat.     

Bioavailability of Petit-Suisse cheese as food vehicle for iron fortification estimated by the prophylactic method

Microencapsulated ferrous sulfate (SFE-171) and ferric orthophosphate in Petit-Suisse cheese were examined for iron bioavailability by the prophylactic method. The iron sources were industrially added to different samples of Petit-Suisse cheese, which were mixed with other food components in our laboratory before use. A reference standard diet inclusive of nonmicroencapsulated ferrous sulfate and a control diet low in iron content were prepared in the laboratory. The final iron content in the fortified diets was approximately 15 mg Fe/kg diet. These diets were administered to weaning rats for 23 days. The iron bioavailability was evaluated as the ratio of iron incorporated into hemoglobin to oral iron intake, thereby being estimated as 62.6 +/- 8.8% for ferrous sulfate and 59.2 +/- 10.6% for SFE-171, which were significantly effective at p < 0.01 compared to 43.4 +/- 10.5% for ferric orthophosphate. It thus turned out that SFE-171 was stable through industrial processing with Petit-Suisse cheese as the food vehicle and served as an iron fortifier equal to ferrous sulfate in bioavailability.