Effect of calcium, copper, and zinc levels in a rapeseed meal diet on mineral and trace element utilization in the rat

Interactive Effects of Selenium, Zinc, and Iron on the Uptake of Selenium in Mycelia of the Culinary-Medicinal Winter Mushroom Flammulina velutipes (Agaricomycetes)

The present study for the first time addressed whether the simultaneous presence of selenium, zinc and iron may have effects on the selenium uptake in the mycelia of the winter mushroom (also known as enoki), Flammulina velutipes. Response surface methodology was used to optimize concentrations of selenium, zinc and iron in the range of 0 to 120 mg L-1. The findings showed that application of selenium, zinc and iron (singly, in pairs, or triads) significantly enhanced the selenium accumulation in the mycelia. The highest amount of the selenium accumulation was observed when selenium (60 mg L-1) and zinc (120 mg L-1) were applied into submerged culture media, concurrently, leading to an 85-fold and 88-fold increase in the selenium content of the mycelia compared to that of the mycelia treated with selenium only and untreated mycelia, respectively. In addition, accumulation of selenium into the mycelia had no deteriorative effects on the mycelial biomass. The findings presented in this study may have implications for daily nutrition and industrial bioproduction of mushroom mycelia enriched with selenium.

Zinc Fractional Absorption from a Representative Diet in Young Chinese Men and Women of the Shandong Rural Region

The objective of this study was to investigate the zinc fractional absorption of young Chinese men and women from the Shandong rural region under the routine dietary pattern by stable isotope technique. Ten men and 10 women, aged 20 to 35 years, and with a representative diet during the experiment were recruited from the Shandong rural region. Stable 67Zn was used as a tracer to label ZnCl2, and Yb was used to monitor the excretion of 67Zn in urine and feces. All volunteers were given rice containing 4.0 mg 67Zn and 1.0 mg Yb on the fourth day. Then the food and fecal samples of all subjects were collected for 12 consecutive days. The total zinc and the stable zinc isotope ratio of all samples were determined by atomic absorption spectrophotometer and thermal ionization mass spectrometer, respectively. The determination of the other nutrients was performed based on the Chinese National Standard Methods. Among volunteers, the daily intake of zinc was 15.50 mg, 103.33 % of recommended nutrient intake (RNI, set by the Chinese Nutrition Society) in men and 15.43 mg, 134.17 % in women. The fractional absorption of Zn was 23.42 ± 2.23 % in men, and 22.49 ± 2.19 % in women. The protein candidates got from the typical diets was 93.96 % of RNI in women. Calcium and ascorbic acid intakes were 76.23 % of RNI and 27.91 % of RNI in men, respectively and 51.17 % of RNI and 34.23 % of RNI in women, respectively. Our results showed that a typical meal for someone in the Shandong rural region presented an adequate intake of zinc and a moderate Zn bioavailability. The shortage of protein and the inappropriate protein pattern may play important roles in reducing zinc bioavailability.

Effects of different sources and levels of copper on growth performance, nutrient digestibility, and elemental balance in young female mink (Mustela vison)

An experiment was conducted in a 3 × 3 + 1 factorial experiment based on a completely randomized design to evaluate the effects of different sources of copper on growth performance, nutrient digestibility and elemental balance in young female mink on a corn-fishmeal-based diet. Animals in the control group were fed a basal diet (containing 8.05 mg Cu/kg DM; control), which mainly consisted of corn, fish meal, meat bone meal, and soybean oil, with no copper supplementation. Minks in other nine treatments were fed basal diets supplemented with Cu from reagent-grade copper sulfate, tribasic copper chloride (TBCC) and copper methionate. Cu concentrations of experiment diets were 10, 25, and 40 mg/kg copper. A metabolism trial of 4 days was conducted during the last week of experimental feeding. Final body weight and average daily gain increased (linear and quadratic, P < 0.05) as Cu increased in the diet; maximal growth was seen in the Cu25 group. Cu supplementation slightly improved the feed conversion rate (P = 0.095). Apparent fat digestibility was increased by copper level (P = 0.020). Retention nitrogen was increased by copper level (linear, P = 0.003). Copper source had a significant effect on copper retention with Cu-Met and copper sulfate treatments retention more than TBCC treatments (P < 0.05). Our results indicate that mink can efficiently utilize added dietary fat and that Cu plays an important role in the digestion of dietary fat in mink, and mink can efficiently utilize Cu-Met and CuSO4.

Inverse correlation between serum calcium and copper levels in male urban Colombian preschool children: relationships with anthropometry and age

Copper and calcium are essential for human growth and development. The present study was conducted to evaluate the relationship between calcium and copper levels, as well as their relationship to age and anthropometry in 180 preschool children ages 2-5 years old. Serum copper levels were inversely correlated with age (r = -0.184, P = 0.032) and height (r = -0.175, P = 0.043) in the whole group and with height for age Z score only in male children (r = -0.291, P = 0.016). The correlation with age is not maintained when it is analyzed for gender. Serum calcium values in the total group were inversely correlated with weight (r = -0.153, P = 0.044) and weight for height Z score (r = -0.246, P = 0.001). No differences were found for gender in the levels of both metals. A negative relationship between serum calcium and copper was found only in male children (r = -0.339, P = 0.005). Studies are required in other populations and experimental designs that can explain an inverse relationship between serum calcium and copper levels.

Whole small fish as a rich calcium source

The present rat balance study investigated Ca availability from the whole indigenous small fish species, mola (Amblypharyngodon mola) from Bangladesh and from skimmed milk. Four groups of six young male rats each were fedad libitumwith diets containing either small fish or milk, at 100 or 160 g crude protein/kg diet dry matter. The study was conducted for 28 d and faeces and urine samples were collected in two balance periods: days 8–14 and 22–28. The Ca and N contents of the diets, faeces and urine were analysed. Ca intake, fractional Ca absorption and Ca retention in relation to N retention were measured. Digestibility and protein utilization of the experimental diets, weight gain of the rats, femur bone weight and mineral composition as well as bone alkaline phosphatase activity were also determined. It was concluded from the values of these variables that Ca from small fish with bones was available and appeared to be a useful Ca source in rats, though perhaps not as available as Ca from milk. This study suggests that small fish with bones may be an important source of Ca in human diets. Promotion of the production and consumption of small fish in population groups with low intakes of milk and milk products should therefore be encouraged.

Assessment of zinc and copper status in weaned piglets in relation to dietary zinc and copper supply

The aim of the study was to determine the effect of weaning and the effect of increasing dietary zinc concentrations on the zinc and copper status of weaned piglets (study 1) and to study the effect of high concentrations of dietary zinc and/or copper on zinc and copper status of weaned piglets (study 2). Study 1 included 54 piglets (six litters of nine piglets). One piglet from every litter was killed 1 day before weaning. The remaining 48 piglets were allocated at weaning (28 days) to four dietary zinc treatments (100, 250, 1000 or 2500 ppm) and subsequently killed 1-2, 5-6 or 14-15 days after weaning. Study 2 included 48 piglets (six litters of eight piglets) allocated to four dietary treatments, consisting of low or high dietary zinc (100 or 2500 ppm) in combination with low or high dietary copper (20 or 175 ppm). All piglets in study 2 were killed 5-7 days after weaning. In both studies, the trace mineral status was assessed by zinc and copper concentrations and alkaline phosphatase (AP) activity in plasma and mucosal tissue. In study 2, lymphocyte metallothionein (MT) mRNA and intestinal mucosa MT mRNA concentrations were included as zinc status markers. The results showed that the zinc status, measured as zinc in plasma and mucosa, was not affected by weaning of the piglets. Plasma copper concentrations decreased during the first 2 weeks after weaning. High dietary copper concentrations did not affect the concentration of copper in plasma, but increased the concentration of copper in mucosa and the concentration of zinc in plasma. The dietary zinc treatments increased the zinc concentration in plasma as well as the zinc and MT mRNA concentration in mucosa. Lymphocyte MT mRNA concentrations did not reflect the differences in dietary zinc supplementation.

Serum concentration and dietary intake of Mg and Ca in institutionalized elderly people

We determined the serum levels and the dietary intake of Mg and Ca in 93 institutionalized elderly people (24 men and 69 women) in Granada (Spain). The serum samples had mean concentrations of 21.39 +/- 2.08 mg/l magnesium and 93.39 +/- 9.24 mg/l calcium. No significant differences were found in the serum levels of the two minerals as regards the sex of the subjects. Application of linear regression analysis to the serum Mg and Ca levels showed a statistically significant positive correlation (P < 0.05). A low vitamin D intake of these subjects (51.8% of the recommended dietary allowance) was observed. The intakes of Ca and Mg correlated positively together, as well as with the intakes of energy, protein, fibre (in the case of Mg only), iron and phosphorus (P < 0.05). The Ca and energy intake were adequate to their current recommendations, as too was the Ca:P ratio, whereas the diet had a poor supply of fibre, vitamin D and Mg.

Relationships between iron and zinc metabolism: predictive value of digestive absorption on tissue storage

The responses of animals to intake of a trace element could vary if it is ingested with a single test meal or due to chronic intake. The metabolic relationships between zinc (Zn) and iron (Fe) were assessed in the young animal by comparing their digestive absorption studied at the beginning of the study with their tissue storage after two months of being fed on experimental diet. Diets supplied adequate intakes of Fe (45 and 300mg/kg diet) and Zn (14 and 45 mg/kg). A significant effect of Fe supply (p < 0.0001) but not of Zn was displayed on Fe absorption; both Fe and Zn diet concentrations influenced Zn absorption (p < 0.01, p < 0.0001). Fe and Zn organ contents significantly correlated with the amount absorbed during the metabolic balance (p < 0.0001). There was a positive correlation between liver, bone, and muscle Fe and Fe absorption (mg/d)(p < 0.0001), and Fe absorption and bone and muscle Zn (p < 0.04) and a negative one with liver Zn (p < 0.0001); a positive correlation was displayed between Zn absorption (mg/d) and Zn organ content (p < 0.0001). There was no correlation between Zn absorption and Fe tissue content (p > 0.05). This study suggests that interactions occur at every step of Fe and Zn metabolism; Fe is more efficient in altering Zn storage than the reverse. The organism seems to be unable to diminish the consequences of an unbalanced diet and digestive absorption. Care must be taken to give the young growing balanced diets.

Dephytinization of a rat diet. Consequences for mineral and trace element absorption

Soaking of a rat diet, high in both plant phytate and phytase, progressively degraded the phytate content with time of soaking. This dephytinization in turn enhanced the digestion of feed organic matter in the animals, and it significantly improved the absorption and retention of minerals and trace elements as observed in balance studies. Incorporation of elements into specific tissues was evaluated as a reflection of bioavailability. Some tissues did reflect the preceding absorption of certain elements; other tissues seemed less suitable as indicators of trace element absorption. Dietary calcium addition in many ways contrasted the soaking procedure: inorganic calcium addition to the feed reduced phosphorus, magnesium, and trace element bioavailability, and interfered with the internal deposition of the elements. The external dephytinization of the feed did not affect the phosphohydrolase activity of the intestinal mucosa as manifested by alkaline phosphatase activity or phytase activity. The mucosal phytase and alkaline phosphatase activities were, however, mutually correlated, supporting the view that "phytase" activity is a less substrate-specific action of alkaline phosphatase activity or a fraction of this activity.

Tissues and organs as indicators of intestinal absorption of minerals and trace elements, evaluated in rats

Tissue and organ deposition and blood parameters were evaluated as indices of mineral and trace element absorption in rats. The absorption of elements was quantified in relation to nitrogen retention, i.e., considering the weight gain and new tissue synthesis. A rapeseed meal diet was supplied with three levels of calcium, two levels of zinc, and two levels of copper in a factorial design. In general, an increase in dietary mineral content increased the relative absorption, which in turn, increased the tissue deposition progressively. Striated muscle, however, did not respond to either an increased calcium or zinc supply. Furthermore, an increased calcium absorption caused a depression of the fractional phosphorus and magnesium content of femur bones. The copper content of the kidneys and the heart muscle was directly proportional to the amount of absorbed zinc and iron, respectively. The iron content of tissue was, in general, inversely proportional to zinc absorption and showed a tendency to be directly proportional to copper absorption. The zinc level in tissues was, in a similar way, inversely correlated to measured calcium absorption. In conclusion, interactions between elements do not only affect the intestinal element absorption, but also the distribution of already absorbed elements in tissues and organs.