Plasma Copper Concentrations Research Articles

Effect of gestational age on cord blood plasma copper, zinc, magnesium and albumin.

The transport of essential trace elements from mother to fetus varies throughout gestation, and the role of transport proteins in the neonate and the mother may change during pregnancy. Magnesium, often used as tocolytic agent, may reach the fetus and appear in cord blood at higher than normal concentrations. To determine cord blood plasma zinc, copper and magnesium concentrations, as well as plasma albumin in premature and full-term newborns, and correlate these values with those of maternal blood plasma at birth. Also, to examine whether cord blood plasma concentration of these elements varies with gestational age. The 35 mother-infant pairs included: 11 in the 38-42-week gestational age (GA), 9 in the 34-37-week GA, 11 in the 29-33-week GA group and 4 in the 24-28-week GA. Magnesium for tocolysis was given to five of the mothers in the 29-33-week GA cohort and two of the women giving birth at 24-28-week GA. Trend analysis showed that while cord plasma zinc decreased with GA at birth, the reverse was observed for copper. There were no differences with GA either in maternal plasma zinc or copper. However, maternal ceruloplasmin tended to decrease with GA (P=0.0174). Maternal and cord blood plasma magnesium exhibited a strong correlation (r=0.942, P<0.001), as well as between cord plasma magnesium and zinc (r=0.448, P<0.01). While the vigorous mother-to-fetus uphill zinc transfer is clear throughout the last trimester, copper remains in cord blood plasma at much lower concentrations than in the mother, suggesting that prematurity may place the newborn infant at a greater risk than the term infant to copper deficiency. This situation, together with a reduced synthesis in the fetus of the transport protein ceruloplasmin, creates another potential challenge in the nutritional support of the premature infant.

Hypertension: does impaired endothelium-dependent relaxation affect superoxide scavenging?

The purpose of this study was to investigate the effects of acute nitric oxide synthase inhibition on mean arterial blood pressure, oxidative stress markers such as plasma malondialdehyde (MDA) concentration, intracellular antioxidant enzyme activities such as copper-zinc superoxide dismutase (Cu/Zn SOD) and catalase and on trace elements important for activity and stability of Cu/Zn-SOD. Wistar-Kyoto rats (approx 150 g) (n=11) were treated with Nomega-nitro-L-arginine methyl esther (L-NAME) (0.5 mg/mL) for 2 d. Age- and bodyweight-matched rats (n=10) were used for control group. Their systolic blood pressures and heart rates were recorded daily during the experimental period and also before their blood samples were drawn. Plasma MDA, plasma and red cell zinc and copper concentrations, and red cell Cu/Zn-SOD and catalase activities were determined. A progressive rise in systolic arterial blood pressure was observed compared to the control group (p<0.001). The heart rate of the experimental group was reduced on the third day (p<0.05). Plasma MDA concentration and red cell catalase activity were increased in the experimental group (p<0.001 and p<0.001, respectively). Plasma copper and red cell zinc concentrations were also increased significantly in the experimental group (p<0.001 and p<0.01, respectively). In conclusion, impairment in endothelium-derived relaxation altered mean arterial blood pressure, oxidant status, and trace element concentrations.

Associations among plasma selenium, zinc, copper, and iron concentrations and immunoregulatory cytokine levels in patients with cutaneous leishmaniasis.

Plasma essential trace elements, selenium, copper, zinc, and iron concentrations and the levels of immunoregulatory cytokines, interleukin-1beta (IL-1beta), interleukin-2 receptor (IL-2r), IL-6, IL-8, and tumor necrosis factor-alpha (TNF-alpha) were evaluated in patients with cutaneous leishmaniasis (CL) to investigate a possible role of these cytokines on selenium, zinc, copper, and iron homeostasis in CL patients. Plasma albumin levels were measured as an index of nutritional status. Plasma selenium, zinc, and iron concentrations, and IL-2r levels were significantly lower, and copper concentrations and IL-1beta, IL-8, IL-6 and TNF-alpha levels were significantly higher in patients with CL than those of healthy controls. There was no significant difference in plasma albumin levels between two groups. There were positive important correlations between plasma selenium and IL-2r, copper and IL-6, and copper and IL-1beta, and negative correlations between selenium and IL-8, iron and TNF-alpha, and zinc and IL-1beta contents in patients with CL. Our results showed that plasma trace element contents change in patients with CL. These changes may not be a result of a specific deficiency from dietary inadequacies or imbalances, but, probably, a result of a part of the defense strategies of an organism that is regulated by immunoregulatory cytokines.

Trace mineral status in post menopausal women: impact of hormonal replacement therapy

The risks of disturbances in trace mineral nutrition and metabolism are high following menopause. The aim of the study was to investigate the trace mineral status in postmenopausal women and the influence of hormonal replacement therapy on this status. Forty-four healthy postmenopausal women, aged 50–60 years old participated in the study. Eighteen were treated by combined hormonal replacement therapy (HRT) per os for at least two years, and 26 were untreated. Plasma trace mineral levels (Zn, Se, Cr, Mn, Cu), red blood cell antioxidant enzymes (Cu-Zn SOD, Se-GPX, Cu), urinary Zn, Cr, Mg, and Ca excretion were measured. Zinc, selenium and manganese plasma levels, activities of Cu-Zn-SOD and GSH-Px in erythrocytes were not statistically different between the two groups. The percentage of zinc plasma levels below the cut off of 10.7 μmol/L was higher in HRT treated group than in untreated one, whereas zinc excretion was reduced. Plasma copper concentrations were higher in women treated by HRT, whereas erythrocyte copper levels were not modified. Plasma chromium concentrations were significantly higher in women receiving HRT and urinary Cr excretion was decreased. The HRT group also exhibited lower losses of urinary zinc and magnesium than untreated women. These data suggest that hormonal replacement therapy provides beneficial effects on trace mineral status related to menopause.

Idiopathic scoliosis and concentrations of zinc, copper, and selenium in blood plasma.

The concentration of zinc, copper, selenium, albumin, and ceruloplasmin in blood plasma and the activity of superoxide dismutase and glutathione peroxidase in erythrocytes were determined in a set of patients with idiopathic scoliosis (n=51). A significant decrease of selenium concentration (0.50 +/- 0.16 micromol/L) was found when compared with a control group (0.69 +/- 0.07 micromol/L) (p<0.01). The same levels of significance were found out for selenium levels corrected for albumin content. In a group of patients with a curvature over 45 degrees indicated for a surgical correction, the average plasma concentrations of selenium were significantly lower (p < 0.05) in comparison with a group of patients with a curvature below 45 degrees treated conservatively. The GSH-Px activity in erythrocytes was the same in both sets. In comparison with the controls, no significant differences were revealed in all of the other parameters. The detection of the decreased blood plasma concentration of selenium has suggested possible disturbance of well-proportioned distribution and of general optimal availability of selenium in the organism of patients with idiopathic scoliosis with likely effects on the process of synthesis and maturation of collagen affecting the axial skeleton stability.

Excessive hepatic copper accumulation in jaundiced rats fed a high-copper diet.

The response of copper metabolism to dietary copper challenge was investigated in jaundiced rats with elevated plasma concentrations of conjugated bilirubin as a result of impaired canicular transport of bilirubin glucuronides. Control and jaundiced rats were fed purified diets with either normal (64 micromol Cu/kg) or high (640 micromol Cu/kg) concentration of added copper. Copper loading produced a greater increase in hepatic copper concentrations in the jaundiced than in control rats. The greater dietary-copper-induced increase in hepatic copper in the jaundiced rats can be explained by the observed smaller rise in biliary copper excretion and a greater efficiency of dietary copper absorption. In individual rats, there was a positive relationship between hepatic copper concentrations and biliary copper concentrations. It is suggested that not the transport of copper from liver cells to bile but that from plasma to bile is diminished in the jaundiced rats. The elevated plasma copper concentrations in the jaundiced rats may support this suggestion.

Effects of tobacco smoking on plasma selenium, zinc, copper and iron concentrations and related antioxidative enzyme activities

Objectives: The aim of the study was to investigate whether alterations in antioxidative enzyme activities are dependent on their cofactor concentrations in tobacco smokers. Design and methods: Plasma selenium, copper, zinc and iron concentrations, and the activities of related erythrocyte antioxidative enzymes copper-zinc superoxide dismutase (Cu-Zn SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were measured in tobacco smokers and compared with those of nonsmokers. Plasma thiocyanate levels were measured as an index of smoking status. Results: While plasma copper concentration and erythrocyte Cu-Zn SOD activity were significantly higher, plasma selenium concentration and erythrocyte GSH-Px activities were significantly lower in tobacco smokers than in nonsmokers. There was no significant difference in plasma iron and zinc concentrations or erythrocyte CAT activity between the two groups. There were significant positive correlations between erythrocyte GSH-Px and plasma selenium levels, between Cu-Zn SOD and copper levels, and between CAT and iron levels, and a negative correlation between plasma thiocyanate and selenium content in tobacco smokers. Conclusions: These findings suggest that antioxidative enzyme activities change depending on their cofactor concentrations in tobacco smokers.

Quantification of Copper in Biological Materials by Use of Electron Spin Resonance

Plasma copper is reportedly increased in pregnancy, infections, and inflammation and decreased in corticosteroid and corticotropin treatment (1). The usual and convenient methods for measurement of metal ions are colorimetry and atomic absorption spectrophotometry (AAS). These methods, however, are not suitable for copper. For example, the molar absorptivity at 480 nm of copper complex with bathocuproine disulfonic acid, the most suitable reagent, is not strong (e = 1.3 × 104) (2)(3)(4), and the atomic absorption at 324.7 nm specific to copper is marginal. As a consequence, both methods require 2 mL of serum, although the copper concentration in plasma is fairly high, e.g., 15.7 μmol/L (1 μg/mL). A more sensitive but selective and convenient method is needed for quantification of small amounts of copper in blood as well as in polluted water, food, and tissues. Electron spin resonance (ESR) is a very sensitive method that requires only 109 spins for detection. We examined the use of ESR for measurement of copper because Cu2+ is paramagnetic, and thus can be measured by ESR, although Cu+ is diamagnetic. We confirmed the results of a previous report that diethyldithiocarbamate (DDC) reacts with Cu2+ at pH 0–10 (5). The Cu2+-DDC complex could be extracted with most organic solvents at these pHs (5)(6). We found that the addition of Na2SO4 facilitated the extraction of the complex with 1-butanol. As shown in Fig. 1A⇓ (spectrum a), Cu2+-DDC in 1-butanol shows a characteristic four-line ESR spectrum with hyperfine splitting of 80 gauss and a splitting factor (g) of 2.047. The height of the peak indicated by the arrow at the highest magnetic field of 3350 gauss was used for the quantification of copper. To liberate copper from bound protein …

The effect of a copper, cobalt and selenium bolus on fertility and trace element status of dairy cattle.

AbstractInfertility is one of the manifestations of clinical copper deficiency in dairy cattle that results from high dietary molybdenum intakes. This trial investigated the effects of slow release glass copper, cobalt and selenium boluses (Cosecure) on the number of inseminations required for confirmed pregnancy, calving interval and trace element status in dairy cattle. Sixty Holstein Friesian dairy cattle were allocated to one of two treatment groups, 30 cattle were treated with two soluble glass trace element boluses (Cosecure®,Telsol Ltd.) on day 0 and 169 while the remaining 30 cattle were left untreated (Controls). The cattle were grazed at pasture (day 0 to 165) which has been shown to contain high levels of molybdenum (range from 2.3 to 3.1 mg/kg DM). Blood samples were taken between days 0 and 280 to measure copper and selenium status and the number of inseminations and calving intervals were recorded. The control cattle required significantly more inseminations to confirmed pregnancy compared with the Cosecure treated cattle (2.5 v 1.7 SEmean 0.16, p&lt;0.01) and had a significantly longer calving interval (397 v 372 days, SEmean 9.2, p&lt;0.05). Plasma copper concentrations were significantly higher in the Cosecure treated cattle on days 30, 78 and 135 (p&lt;0.01) compared with the controls, although the controls were all in the normal range (&gt; 12 μmol/l). Cosecure treated cattle had significantly higher glutathione peroxidase (GSHPx) activities on day 246 (P.0.05). However, on all sample dates, the GSHPx activities were in the normal range for both treatment groups (&gt;40units/ml PCV). The dietary cobalt intakes of the cows were measured (1.5 to 2.1 mg/kg DM in grass and 2.1 to 2.7 mg/Kg DM in compound) and found to be well in excess of the requirement of 0.2 mg/Kg DM. It was concluded that treatment with slow release glass copper, cobalt and selenium boluses (Cosecure) reduced the number of inseminations required for conception in the dairy cows due to the slowly released copper.

Copper responsive infertility in British cattle: the use of a blood caeruloplasmin to copper ratio in determining a requirement for copper supplementation

AbstractSigns of clinical copper deficiency in ruminant animals include infertility. Blood copper concentrations alone are not an adequate indicator of copper status, as they take no account of the thiomolybdate challenge to the animal. The use of the ratio of caeruloplasmin activity to plasma copper concentration should provide a better indicator of molybdenum induced copper problems. The objectives of this study were to obtain veterinary feedback on the University of Leeds Trace Element Laboratory's (ULTEL) assessment of copper status and responses to any recommended supplementation. Blood samples from 713 female cattle from 114 herds were assessed for copper status, including plasma copper concentrations, serum caeruloplasmin activities and the ratio between the caeruloplasmin and plasma copper (CP/PlCu ratio). On the basis of only plasma copper analysis 95.0 % of the cattle were classified as being of normal copper status using Veterinary Laboratory Agency reference ranges. However, when the CP/PlCu ratio was also considered only 35.6 % of the cattle would be classed as having normal copper status. Appropriate copper supplementation would be required by 30.7 % of the cattle and a further 27.8 % could also benefit from additional copper. Veterinary responses to a questionnaire (80 % returned) indicated that infertility was a major problem in their clients’ herds. Where copper supplementation was recommended and administered an increase infertility was observed. In herds showing poor or lack ofoestrous behaviour/ later embryo loss (signs of clinical copper deficiency), 91.7 % reported that these signs were reduced by copper supplementation. The relevance of the CP/PlCu ratio as a diagnostic aid in the identification of copper responsive infertility has been supported by the responses of the veterinary surgeons.

The effect of a zinc, cobalt and selenium soluble glass bolus on the trace element status of extensively grazed sheep over winter

AbstractThe effects of trace element deficiencies in lambs, particularly zinc, copper, cobalt and selenium, include decreased growth rates and increased mortality. However, trace element supplementation of sheep reared under extensive conditions has several logistical problems.Two trials were designed to investigate the effect of a zinc, cobalt and selenium soluble glass bolus on the trace element status of out-wintered ewe lambs. In trial 1 600 8-month-old ewe lambs (500 Scottish Blackface and 100 North Country Cheviots) were allocated to two treatment groups; 300 were treated with a zinc, cobalt and selenium soluble glass bolus (zinc) and 300 were untreated (control). In trial 2, 315 8-month-old Scottish Blackface ewe lambs were allocated to three treatments: 105 were treated with the zinc, cobalt and selenium soluble glass bolus (zinc), 105 were treated with a copper, cobalt and selenium soluble glass bolus (copper) and the remaining 105 were untreated (control). Blood samples were collected immediately prior to giving boluses and again after approximately 4 months. These were assessed for zinc (plasma zinc concentration), cobalt (serum vitamin B12concentration), selenium (erythrocyte glutathione peroxidase activity) and copper status (plasma copper concentration, caeruloplasmin, amine oxidase and superoxide dismutase activity and calculation of the ratio between the caeruloplasmin and plasma copper).The zinc bolus in both trials significantly increased the plasma zinc concentrations (P&lt; 0·001 andP&lt; 0·01 respectively), erythrocyte glutathione peroxidase activities (P&lt; 0·001) and serum vitamin B12concentrations (P&lt; 0·001). The copper bolus also significantly increased the erythrocyte glutathione peroxidase activities (P&lt; 0·001) and serum vitamin B12concentrations (P&lt; 0·001) when compared with the controls but were not significantly different from the zinc group. The copper bolus significantly increased all of the copper status indicators (P&lt; 0·01) when compared with the control and zinc groups. However, in trial 1 when only the zinc and control groups were compared, the zinc bolus significantly increased the ratio (P&lt; 0·001) and serum caeruloplasmin (P&lt; 0·001) and erythrocyte superoxide dismutase (P&lt; 0·01) activities. These responses were not observed in trial 2 with the erythrocyte superoxide dismutase being significantly reduced in the zinc group when compared with the control group (P&lt; 0·001).The zinc, cobalt and selenium soluble glass bolus increased the status of all three trace elements consistently for a period of at least 100 days. The increases of cobalt and selenium status were similar to those achieved using the copper, cobalt and selenium bolus, which also increased the copper status of the sheep.

Determination of Normal Blood Concentrations of Lead, Zinc, Copper, and Iron in Hispaniolan Amazon Parrots (Amazona ventralis)

Lead, zinc, copper, and iron toxicities are major concerns affecting both wild and captive avian populations. Reference ranges of blood concentrations of these metals in large numbers of birds with no history of environmental exposure have not been reported. This study reports ranges for whole-blood (lead) or plasma (zinc, copper, and iron) concentrations for lead, zinc, copper, and iron in 45 Hispaniolan Amazon parrots that had minimal environmental exposure to any of these metals. Measurements of plasma zinc, copper, and iron concentrations followed a normal distribution, which resulted in reference ranges (mean ± 2 SD) of 1.25–2.29 ppm, 0.07–0.19 ppm, and 2.25–6.25 ppm, respectively. All whole-blood lead concentrations were below 0.02 ppm, and a reference range could not be determined.

The impact of calcium, magnesium, zinc, and copper in blood and seminal plasma on semen parameters in men

To investigate the impact of calcium, magnesium, zinc, and copper in blood and seminal plasma on semen parameters, 107 fertile and 103 subfertile males provided a standardized blood and semen specimen. Total calcium and magnesium concentrations were determined with colorimetric end point assay procedures. Zinc and copper were determined by flame atomic absorption spectrophotometer (AAS). Semen analysis was performed according to World Health Organization guidelines (1992). The concentrations of calcium, magnesium, zinc, and copper in blood and seminal plasma were not different between the subfertile and fertile group. Weak correlations were demonstrated between blood plasma zinc concentrations and sperm count (r s = 0.18), sperm motility (r s = 0.15), and abnormal sperm morphology (r s = 0.13). Zinc and magnesium concentrations in seminal plasma correlated weakly with sperm count (r s = 0.17 and r s = 0.16, respectively), and copper concentrations in blood plasma with motility (r s = 0.25). Strong correlations were found between calcium, magnesium, and zinc in seminal plasma. Although calcium, magnesium, zinc, and copper play an essential role in spermatogenesis and fertility, the determination of these elements in blood and seminal plasma does not discriminate on the basis of fertility in this group of men.

Effect of a copper, cobalt and selenium soluble glass bolus given to grazing sheep

Three field trials were carried out to evaluate the performance of a sintered soluble glass copper, cobalt and selenium bolus for maintaining adequate levels of the three trace elements. Trial 1 used 34 growing lambs, trial 2 used 36 growing lambs whilst trial 3 used 50 year-old non productive female sheep. In each trial half the sheep had a bolus administered (bolused) and half remained as controls. Blood samples were taken immediately prior to bolus administration and then at regular intervals throughout each trial. The samples were analysed for copper status (serum caeruloplasmin activity and plasma copper concentration), cobalt status (serum vitamin B 12 concentration) and selenium status (erythrocyte glutathione peroxidase activity). For trial 1 the bolused sheep at all post treatment samplings (days 20, 42 and 63) were significantly increased in both cobalt and selenium status ( P<0.001) compared to the controls, however, there were no significant differences in any other blood parameter. For trial 1 liver copper concentrations were analysed on slaughter samples and were significantly increased for the bolused lambs ( P<0.001). In trial 2 the bolused sheep had significantly increased selenium and cobalt status ( P<0.001) for all samples (days 28, 51, 69, 91). In trial 3 the selenium status of the bolused sheep was significantly increased at all three samplings (day 21, P<0.05 and days 51 and 105, P<0.001), whilst the cobalt status was also significantly increased on all sample days (day 21, P<0.05; day 51, P<0.01 and day 105 P<0.001). The sintered soluble glass copper, cobalt and selenium bolus was able to prevent or correct deficient and/or marginal cobalt and selenium status of sheep throughout these trials. The bolus had little measured effect on the already adequate blood parameters of copper status, although the liver copper concentrations of the bolused sheep were higher in the trial for which they were analysed.

High arsenic intake raises kidney copper and lowers plasma copper concentrations in rats.

The effect of high arsenic intake on copper metabolism was investigated. Male rats aged 6 wk had free access to purified diets containing either 0 or 100 mg As/kg diet and demineralized water for a period of 2 wk. Arsenic was added to the diet in the form of NaAsO2. The high-arsenic diet decreased feed and water intake and body weight gain, but significantly increased liver weight. Kidney weight was not affected. Arsenic feeding drastically elevated kidney copper concentration, but significantly reduced copper concentration in plasma. Both true absorption and biliary excretion of copper were decreased significantly in rats fed the high-arsenic diet. True copper absorption was lowered essentially through the lower copper intake in the rats fed arsenic. It is speculated that arsenic feeding primarily leads to copper accumulation in the kidney, followed by a decrease in feed intake and thus in true, absolute copper absorption, a decrease in plasma copper concentration, and a decrease in biliary copper excretion.

Analysis of serum copper and zinc concentrations in cancer patients.

Several studies have shown that plasma copper concentrations are increased in various carcinomas. Zinc acts as a cellular growth protector, including growth of neoplastic cells, and its deficiency was demonstrated to be involved in several stages of malignant transformation. However, the usefulness of the serum zinc and copper determinations in cancer prevention, detection, monitoring treatment, and prognosis requires further investigations. The aim of the present study was to compare the serum copper and zinc levels in patients with cancer of the lung (PC), breast (BC), gastrointestinal tract (GIC), and gynecological (GYNC) malignancy with progress of the disease. The results of the study have shown a significant increase in the mean total serum Cu levels and the serum Cu/Zn ratio in all patient groups with cancer compared to a control group. Increased mean serum concentrations and Cu/Zn ratios were found in the whole group (ALLC), and for the GIC and GYNC groups with local as well as metastasized (Meta) disease in comparison with the control group. The mean serum concentrations of Zn were decreased only in metastasized ALLC and GYNC groups.

Evaluation of superoxide dismutase and glutathione peroxidase enzymes and their cofactors in Egyptian children with Down's syndrome.

The present work investigated the activity of Cu/Zn superoxide dismutase enzyme (SOD) in red blood cells and glutathione peroxidase enzyme (GPx) in whole blood by spectrophotometric methods. Plasma levels of the cofactors copper and zinc and whole-blood selenium were evaluated using atomic absorption spectrophotometer. The study included a population of 18 Down's syndrome (DS) patients with complete trisomy 21 (group 1), translocations (group 2), and mosaicism (group 3), and their 15 matched controls. The purpose of this work was to study the gene dosage effect of SOD and its consequence on GPx enzyme and the various cofactors, and to find out correlations with developmental fields. Our results showed that in the population with complete trisomy 21 and translocations, SOD and GPx activities were increased, whereas in cases with mosaicism, the enzymes activities were within normal limits. Plasma copper concentrations were increased, whereas whole-blood selenium concentrations were significantly decreased in the three DS groups. Plasma zinc levels were within normal in all patients. We concluded that changes in trace elements and enzyme activities were not related to age or sex. Also, there was no correlation between the enzyme levels and the developmental activities. Our results are useful tools for identifying nutritional status and guiding antioxidant intervention.

Trace-element status in milk and plasma of Kuwaiti and non-Kuwaiti lactating mothers

There is a wide variation in the reported data on the concentrations of trace elements in human milk from different countries, but such data are not available for Kuwait. The objective of this study was to analyze the concentration of zinc, copper, manganese, and iron in milk and plasma of Kuwaiti and non-Kuwaiti mothers during prolonged lactation. Milk samples (from 34 donors) were collected early in the morning before feeding the infant. Trace elements were analyzed using atomic absorption spectrophotometry. Protein content and activity of superoxide dismutase were assayed spectrophotometrically. Concentration of zinc, copper, iron, and total protein and activity of superoxide dismutase in milk and of only zinc in plasma of Kuwaiti mothers were significantly higher than those of non-Kuwaitis. Concentration of zinc, copper, manganese, and total protein in milk of both groups decreased as lactation continued but that of milk iron and plasma trace elements remained unchanged. The data of Kuwaiti mothers are consistent with those of previous reports on hyperurecemia, and the prevalence of obesity was found to be higher in the Kuwaiti population than in other countries. High protein content in association with high concentration of trace elements in milk of Kuwaiti versus non-Kuwaiti mothers may indicate that protein content in milk is an important determining factor for the concentration and bioavailability of these elements.

Milk Fat Composition of Holstein and Jersey Cows with Control or Depleted Copper Status and Fed Whole Soybeans or Tallow

We studied effects of breed, dietary fat source, and dietary copper intake as factors known to influence unsaturation of milk fat and its potential for development of spontaneous oxidized flavor in milk. Twelve Holstein and 12 Jersey cows were allotted to three blocks with four cows of each breed. Cows within breed were allotted randomly within blocks and fed control or copperdepleting diets for 2 mo to achieve stable or depleted liver copper stores. Cows then were fed tallow or roasted whole soybeans in a two-period switchback (5 wk per period); during the last week of each period additional vitamin E (2000 IU/d) was added. Copper depletion for 2 mo decreased concentrations of copper in liver. Feed intake and milk yield were influenced only by breed. The proportions of C4:0 to C14:0 and C18:0 in milk fat were higher, whereas C16:1 and cis-C18:1 were lower in Jersey cows. Feeding soybeans increased C4:0 to C14:0, C18:0, C18:2, and C18:3 in milk, and decreased C14:1, C16:0, C16:1, trans-C18:1, and cis-C18:1. Depleted copper status increased conjugated linoleic acid in milk. Several breed x fat source interactions for individual milk fatty acids occurred. Feeding soybeans decreased plasma concentrations of copper and zinc, and increased concentrations of α-tocopherol in plasma and milk. The concentration of zinc was higher in milk of Jersey cows. Depleted copper status tended to increase copper concentration in plasma and decreased copper in milk. Fat source did not influence plasma copper concentration when status was adequate, but plasma copper concentration was higher when tallow was fed to cows with depleted copper status. Supplementing vitamin E increased concentration of α-tocopherol in plasma and milk and decreased concentration of zinc in milk. Factors influencing the potential for oxidized flavor development in milk can be manipulated by changing the diet of the cow.

Plasma Copper Concentration as Marker of Copper Intake from Food

Copper concentration in blood plasma is used mainly as an indicator for alimentary copper supply. This has some limitations because copper concentration in plasma fluctuates with age, exercise and health status and does not increase after a meal nor decrease during short-term fasting. The Austrian Study on Nutritional Status (ASNS) provides data on nutrient intake and corresponding plasma concentrations, permitting to evaluate the suitability of copper plasma concentration as a marker of copper intake. Copper intake and intake of relevant nutrients and food groups were evaluated from 7-day weighed food records from 2,400 preschool and schoolchildren between 4 and 19 years of age. Blood samples were collected from a subgroup of 1,400 of these children. The copper concentration in plasma was measured by graphite furnace atomic absorption spectrometry. Correlations between plasma concentrations and intake of nutrients and food groups were calculated using a stepwise linear regression model. The results showed that the determination of copper plasma concentrations are inadequate to predict copper intake from dietary records. A better indicator for copper supply may be the evaluation of those food items, which are the predominant sources of copper intake at the population level. The highest influence on copper plasma concentration was found for the intake of meat, representing not only the most important food group for copper supply but also the most important food group for fat and protein supply. The individual copper status can only be estimated accurately when information on characteristic enzyme activities under control of additional factors of influence or even body stores of copper are available.