Selenium content of commercial formula diets

Enteral nutrition in Crohn's disease: an underused therapy

This paper reviews the literature on the history, efficacy, and putative mechanism of action of enteral nutrition for inflammatory bowel disease in both paediatric and adult patients. It also analyses the reasoning behind the low popularity of exclusive enteral nutrition in clinical practice despite the benefits and safety profile.

Serum concentrations of trace elements in patients with Crohn's disease receiving enteral nutrition

We investigated the trace element status in Crohn's disease (CD) patients receiving enteral nutrition, and evaluated the effects of trace element-rich supplementation. Thirty-one patients with CD were enrolled in this study. All patients were placed on an enteral nutrition regimen with Elental(R) (Ajinomoto pharmaceutical. Ltd., Tokyo, Japan). Serum selenium, zinc and copper concentrations were determined by atomic absorption spectroscopy. Serum selenoprotein P levels were determined by an ELISA system. Average serum levels of albumin, selenium, zinc and copper were 4.1 +/- 0.4 g/dl, 11.2 +/- 2.8 microg/dl, 71.0 +/- 14.8 microg/dl, and 112.0 +/- 25.6 microg/dl, respectively. In 9 patients of 31 CD patients, serum albumin levels were lower than the lower limit of the normal range. Serum selenium, zinc and copper levels were lower than lower limits in 12 patients, 9 patients and 1 patient, respectively. Serum selenium levels significantly correlated with both serum selenoprotein P levels and glutathione peroxidase activity. Supplementation of selenium (100 microg/day) and zinc (10 mg/day) for 2 months significantly improved the trace element status in CD patients. In conclusion, serum selenium and zinc levels are lower in many CD patients on long-term enteral nutrition. In these patients, supplementation of selenium and zinc was effective in improving the trace element status.

Selenium content of Spanish infant formulae and human milk: influence of protein matrix, interactions with other trace elements and estimation of dietary intake by infants

The selenium content of infant formulae varies as a result of differences in the amount of intrinsic selenium compounds. Manufacturers have been gradually changing the protein profile of infant formulae to reflect human milk contents more closely. Because of these variations in infant formula composition and their potential impact on selenium content, this trace element was analysed with regard to the different protein sources. The aims of this study were to determine the selenium content in infant formulae sold commercially in Spain, to estimate a daily dietary intake for infants fed on formulae and to compare with the selenium provided by Spanish breast milk samples used as a reference. We have also identified certain trace elements added to formulae which interact with selenium according to the type and protein matrix of the infant formulae. Selenium concentration was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) with a hydride generator. The selenium concentrations in human milk and infant formulae determined in this study are similar to those found by other researchers in different countries. The daily selenium intake from the formulae studied was estimated according to the recommended doses from the manufacturers. The theoretical selenium intake of nursed infants has been studied in relation to the Recommended Dietary Allowance (RDA: 10 microg Se/day) and the specific recommendations for infant formula nutrient contents (10-35 microg Se/L) set by the Expert Panel of life Sciences Research Office (LSRO) of the American Society for Nutritional Sciences. According to our results, on an overall view, infants fed on the studied infant formulae have an intake between basal and normative requirements. This might be considered as providing an adequate selenium supply. However, the intake of setenium provided by several formulae included in this research did not reach the RDA for the first month of neonate life.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

Selenium content of breast milk

Selenium levels in human milk in the winter period ranged from 5.3 micrograms/l to 23.8 micrograms/l, the mean value being 11.0 micrograms/l. The nursing women were divided into several groups according to the results of a questionnaire, i.e. according to their social status (refugees or otherwise), number of deliveries, post partum days, the weight they had gained during pregnancy, their age and smoking habits. The mean levels of selenium for each group are presented. Selenium was determined by hydride generation atomic absorption spectrometry.

Selenium in uremia

The importance of selenium as an essential trace element for man has been increasingly recognized during the last several years. Selenium deficiency has been associated with cases of congestive cardiomyopathy, skeletal myopathy, anemia, enhanced cancer risk, elevated incidence of cardiovascular disease, immune system alterations, hair and nail changes, and abnormalities in thyroid hormone metabolism. These symptoms are frequently present in chronic uremic patients. Nevertheless, the prevalence and significance of selenium deficiency in the uremic syndrome is still not clearly defined. This article reviews the selenium status in chronic uremic patients, the supposed pathogenetic mechanisms of selenium disturbance in uremia, and the possible role of selenium deficiency on some uremic abnormalities.

The necessity of selenium substitution in total parenteral nutrition and artificial alimentation

For the trace element selenium, in contrast to zinc, iron, copper, chromium, manganese and iodine, there is still no clear official recommendation with regard to routine substitution in artificial nutrition. An overview of the manifestations of selenium deficiency in humans during the period 1979-1995 shows that nutritive deficiencies are exclusively TPN-induced or the result of severe malnutrition. The pathology of TPN-induced selenium deficiency and the analytic assessment of selenium status are described. Patients undergoing long-term parenteral nutrition or suffering from an increased loss of intestinal secretions have to be characterized as being especially at risk for clinical selenium deficiency. The relationship of the serum selenium kinetics in pediatric and adult patients to the depletion of body compartments during the course of short-term and prolonged TPN is discussed. Because of the importance of the selenoproteins, the regularly occurring depletion during selenium-free TPN and the borderline supply of selenium in Germany the routine substitution of selenium in TPN is strongly recommended. The pharmaceutical industry should be encouraged to develop a trace element solution that includes selenium, so that the nutritive requirement of patients on TPN can be satisfied. Adequate intravenous dosage recommendations are based on maintenance of glutathione peroxidase homeostasis. The routine supplementation dosage may not meet the selenium requirements of intensive care patients under conditions of increased metabolic demands on their anti-oxidative system.

GFAAS determination of selenium in infant formulas using a microwave digestion method

A method for determining the selenium content of infant formulas is proposed. It includes wet digestion with nitric acid and hydrogen peroxide in medium pressure teflon bombs in a microwave oven and determination by graphite furnace atomic absorption spectrometry (GFAAS). The absence of interferences is checked. Values obtained for the limit of detection (19.4 ng/g), precision (RSD = 2.2%) and accuracy by analysis of a reference material show that the method is reliable.

Selenium deficiency in long-term total parenteral nutrition

Although selenium is an essential trace element, it is often not routinely added to total parenteral nutrition (TPN) formulations. When selenium is not added, patients are at risk for selenium deficiency. This report describes such a patient. He had several operations for colon cancer, including a massive resection of the small bowel that resulted in a short bowel and a fistula. TPN was started after his last operation. After he was discharged, he had a normal, active lifestyle, except that he limited oral intake to water and an occasional soft drink. After 3 years of almost exclusive nourishment by TPN, he developed whitened nail beds. Investigation for possible trace element deficiency resulted in a finding that he had very low levels of selenium in his blood. He did not have any of the cardiac or skeletal muscle abnormalities that have been associated with selenium deficiency. After supplementation with selenium, his blood levels of selenium rose and the nail bed changes were reversed.

Minerals and trace elements in milk

The nutritional roles, requirements, and metabolism and the quantitative relationship between dietary intakes and health for a number of the minerals and trace elements have been more clearly defined in recent years, but there are still considerable deficiencies in our understanding of these issues, e.g., the significance of calcium in the etiology and treatment of osteoporosis and hypertension. Reliable information is now available on the content, and the principal factors affecting it, of most of the minerals and trace elements in human and cow's milks. However, for some of the trace elements, there is still a wide variation in reported values in the literature, which is due, at least in part, to analytical difficulties. The contribution of cow milk and milk products to the diet in Western countries is significant for sodium, potassium, chloride, calcium, phosphorus, zinc, and iodine. Iodine is the only trace element for which there has been any suggestion of excessive amounts in cow milk. However, there is evidence of a decline in milk iodine concentrations in the United States in recent years, although the situation in other countries less clear. Breast milk usually has adequate mineral and trace element contents for feeding full-term infants, with the exceptions of fluoride, for which supplementation of infants is recommended, and of selenium in some countries, such as Finland and New Zealand, where maternal intakes are low. However, breast milk selenium contents have increased in these countries in recent years due to increased maternal selenium intakes. The concentrations of minerals and trace elements in infant formulas for full-term infants are generally higher than in human milk, and all appear to be more than adequate, with the possible exception of selenium, which may need to be increased in some formulas. Considerable changes in the mineral and trace element contents of formulas have been instituted in recent years in the light of improved knowledge of infant requirements. While the chemical forms of the macrominerals and some of the trace elements (iron, zinc, copper, and manganese) in milks are fairly well defined, the forms of many of the trace elements are unknown. Sodium, potassium, chloride, and iodine are believed to be almost totally absorbed from milks and infant formulas.(ABSTRACT TRUNCATED AT 400 WORDS)

Platelet glutathione peroxidase activity in long-term total parenteral nutrition with and without selenium supplementation

Selenium (Se) is not routinely included in total parenteral nutrition (TPN) solution; thus, patients receiving long-term TPN may be at risk of Se deficiency, which may cause fatal cardiomyopathy. Platelet glutathione peroxidase (GSH-Px) activity, as well as Se levels and GSH-Px activity in plasma and erythrocytes during prolonged TPN, was measured in six patients with chronic gastrointestinal disease. During the time course of TPN, Se administration was discontinued for 12 weeks, and then resupplemented for another 12 weeks. Before the study period, all Se indices had been maintained within the normal range. After discontinuation of Se supplementation, a significant decrease in platelet GSH-Px activity was observed after 1 week (from 64 +/- 7 [mean +/- SD] to 39 +/- 5 U/g of protein). After resupplementation, it increased after 1 week (from 44 +/- 9 to 65 +/- 10 U/g of protein). Plasma Se indices significantly changed within 3 weeks after withdrawal and reintroduction of Se (Se: from 136 +/- 28 to 75 +/- 14 and from 61 +/- 22 to 125 +/- 33 micrograms/L; GSH-Px: from 236 +/- 50 to 140 +/- 36 and from 128 +/- 32 to 220 +/- 64 U/L). Erythrocyte Se indices showed no significant changes during the study period. The results demonstrate that platelet GSH-Px activity is the most sensitive index of Se status in TPN patients.

Chemical stability of selenious acid in total parenteral nutrition solutions containing ascorbic acid

Reduction of selenious acid (H2SeO3) to elemental Se by ascorbic acid was investigated in regard to the stability of selenite in total parenteral nutrition (TPN) solutions. [75Se] H2SeO3 (100 micrograms Se/liter) was incubated at 25 degrees C with pure ascorbic acid (100 or 500 mg/liter) or added to complete TPN solutions containing similar levels of ascorbate. The mixtures were subjected to thin layer electrophoresis at pH 5.3 to separate HSeO3- from Se degree. In complete TPN formulas, little or no reduction of HSeO3- to Se degree occurred over a 24-hr period, whereas complete reduction occurred with pure ascorbic acid. Further experiments showed that the amino acid component of the TPN formula was preventing the reduction of selenite, and that reduction of selenite by ascorbate did not occur in buffered solutions having a pH of 5 or greater. These results show that reduction of selenite is strongly influenced by pH. At the concentrations of H2SeO3 and ascorbic acid commonly used, reduction to elemental Se is unlikely to be a practical problem in TPN solutions in the near-neutral pH range.

Selenium: clinical significance and analytical concepts

Selenium is an essential trace element in humans and animals. Its only established function in humans is the antioxidant activity of glutathione peroxidase, a selenoenzyme. Severe prolonged deficiency may cause a fatal cardiomyopathy. Iatrogenic causes of selenium deficiency include parenteral and enteral nutrition. Low plasma selenium is also found in malabsorption, cystic fibrosis, rheumatoid arthritis, neoplasia, and other varied clinical disorders. Death has resulted from a single massive ingestion of selenium, while chronic excessive intake causes skin, nail, and hair pathology. Extreme geographical variation in population blood and urine selenium levels and a marked age-specific variation in population reference intervals are important factors in understanding selenium nutrition. Nutritional requirements, biological availability, and metabolism are discussed in relation to geographical, age, and method variability. Sampling, processing procedures, and methods for selenium quantitation are reviewed. Selenium content in different biological matrices and reference values for pediatric, adult, and obstetric populations are provided.

Determination of selenium in biological matrices

The definitive IDMS method has the advantage of good detection limits and precision. The advent of the new, smaller, easy-to-use GC/MS system should make this method more popular. The fluorometric method remains the method of choice for the determination of selenium in many matrices if the limitations of the method are understood. The newer methods include gas chromatography, HG-AAS, and GFAAS. The gas chromatography methods show promise because of the relatively simple instrumentation needed and the fact that the analyte is separated from the matrix. HG-AAS offers good sensitivity provided care is taken to ensure complete sample digestion and conversion of selenium to selenite. The advent of Zeeman background correction systems for GFAAS has greatly facilitated selenium determinations, particularly in biological matrices where iron and phosphorus are also present. The reference materials now available, used as part of a quality assurance program, should help to ensure accurate determinations, permit method validation, and allow performance evaluation in interlaboratory trials.

Reduced plasma and white blood cell selenium levels in haemodialysis patients

Selenium concentrations have been measured in plasma and in blood leucocytes from 29 haemodialysis patients and from 25 healthy men. The selenium contents of the plasma and white blood cells of the dialysis patients were significantly reduced (p less than 0.001). Selenium deficiency in humans results in a congestive cardiomyopathy and is associated with increased risks of accelerated atherosclerosis and cancer. Each of these is found with abnormal frequency in haemodialysis patients.

Selenium content of enteral formulas

Selenium content of several complete enteral formulas and modular enteral components was determined by neutron activation analysis. Formulas based on egg albumin provided the highest content of selenium. Most of the remaining formulas had selenium contents that would provide an amount less than the proposed safe and adequate range of intake. Selenium supplementation should be considered for these latter formulas.

Dietary selenium intake in Belgium for different population groups at risk for deficiency

An estimation of the dietary selenium intake in different population groups in Belgium has been carried out. 24 h duplicate meals and food consumption statistics combined with concentration levels in different foods, as determined by hydride generation atomic absorption spectrometry, are used. Dietary intake of selenium is low to very low, especially for vegetarians (12.7 +/- 9.1 micrograms) and patients on long-term total parenteral nutrition (1.2 +/- 0.8 microgram). The different intakes are discussed and compared with intakes published for other countries, while the importance of bioavailability of the selenium in food in the risk of deficiency is stressed.

Prediction of whole blood selenium levels in patients on long-term parenteral nutrition

In an attempt to define clinical variables which might predict the whole blood selenium level prior to supplementation, whole blood selenium levels were determined in 21 home parenteral nutrition patients who were not receiving selenium supplementation. These levels were examined for possible correlations by single and multivariant analysis with the following clinical parameters: age at initiation of home parenteral nutrition, months of home parenteral nutrition received, hematocrit, albumin, estimated length of remaining small bowel, kilocalories per kilogram actual body weight infused per day, grams protein per kilogram actual body weight infused per day, and multiple of ideal body weight. Of all the combinations of variables examined, the best correlation obtained was between whole blood selenium levels and the total kilocalories per kilogram body weight per day delivered intravenously (r = -0.89, p less than 0.001). A statistically significant correlation (r = -0.67, p less than 0.01) was also observed between selenium levels and the grams protein per kilogram actual body weight infused per day. However, inclusion of this or additional variables did not increase the predictive value of the equation describing whole blood selenium levels as a function of the calories delivered. The implication of this study is that patients requiring more intensive nutritional support develop lower selenium levels during the course of treatment. Despite these correlations, no single clinical parameter or combination of parameters, however, was of sufficient predictive value to preclude laboratory determination of whole blood selenium values in deciding which patients might benefit from selenium supplementation.

Selenium deficiency

Selenium is undoubtedly an essential trace element: its involvement in GPx structure, the presence of deleterious effects of selenium deficiency in animals, and the recognition of deficiency states in man attest to its importance. However, if the consequences of selenium deficiency in man are now widely recognized, the mechanisms underlying these conditions are poorly understood. The definition of the exact role of selenium in human homeostasis has been hampered by the lack of a sensitive parameter, usable in routine investigation, to assess selenium status. Measurements of plasma and urinary levels, although useful in clinical practice, are inadequate indicators. The only true evidence of selenium deficiency lies in a positive response to selenium therapy. Deficiency states have been demonstrated for inhabitants of regions where selenium supply is limited, in protein-energy malnutrition, and in patients maintained on total parenteral nutrition without selenium supplementation. The benefit of selenium supplementation, together with other antioxidant drugs, in non-deficient subjects is still a matter of debate; its protective effect in neoplastic, cardiovascular and neurological degenerative diseases is not yet proven.

Trace element metabolism in the fetus and neonate

The effects of trace metal nutrition on the fetus and neonate have been described. Since very little research has been done with the human fetus and neonate, much of our knowledge must be extrapolated from animal studies. In addition, most of the work centres around the effects of copper and zinc nutrition. Nutritional requirements (when known) for both enteral and total parenteral feeding of certain trace metals, as well as the bioavailability, have been discussed. Finally, methods of assessment of trace metal nutritional status have been discussed. These include direct measurement of metal concentrations and determination of biochemical indicators, such as metal-dependent enzyme activities--both of which are static indicators of nutritional status, and functional assessment of nutritional status which is a dynamic measure of trace metal nutrition and includes tests measuring the effects of metal nutrition on the function of cells, tissues, organs, and the host in general.

Selenium intake of infants and young children, healthy children and dietetically treated patients with phenylketonuria

In 20 healthy infants and children, 5-20 months old, the Se intake was estimated by analysing food samples by instrumental neutron activation analysis. The intake was calculated by weighing the portions offered and actually consumed. The median Se content of the food amounted to 27 ng/g wet weight (gww) and median daily Se intake to 33.5 micrograms. The Se intake was not equally distributed over the day. About 50% of the daily Se intake was derived from the supper. The main Se sources (41%) for young children were cereal paps. Commercially available meals (30 ng/g) contained less Se than home-made ones (50 ng/g). In nine dietetically treated patients with phenylketonuria the median Se intake amounted only to 6.9 micrograms/day corresponding to a mean Se content of the diet of 7.9 ng/g. The main Se source in the diet was vegetables (36.3%) and 20% derived from their protein supplements. The Se intake of young children, healthy or dietetically treated, cannot be calculated accurately from tables but must be estimated by measuring the Se content of the local food because cereals and vegetables--the main Se sources--exhibit great regional variations.

Selenium depletion in burn patients

Victims of major burns may be at risk for selenium (Se) depletion because increased postinjury nutrient needs are often met by total parental nutrition and tube feedings which contain little Se. This study compared Se status of 17 burn patients and 191 healthy control subjects. Se intake of burn patients was lower than the intake of control subjects when total parenteral nutrition or tube feedings were used as primary nutrient sources but was comparable to the control intake when burn patients consumed oral diets. Serial determinations each 10 days during recovery showed that burn patients had lower plasma Se, erythrocyte Se, and erythrocyte glutathione peroxidase levels, and lower 24-hr urine Se excretion. These results provide biochemical evidence of Se depletion despite exogenous Se intake within the range recommended for healthy adults. Further studies are indicated to determine if Se depletion in burn patients can be prevented by Se supplementation of total parenteral nutrition and tube feeding solutions.

Suboptimal selenium status in home parenteral nutrition patients with small bowel resections

The selenium status of 13 adult home parenteral nutrition (HPN) patients was evaluated using 12 healthy adult volunteers as controls. Patients had been maintained on HPN for a mean of 36 months and averaged 121 cm of residual small bowel. Prospective diet surveys in patients indicated a mean oral caloric intake of 902 kcal/day. The mean plasma selenium concentrations (microgram/g) were 0.044 in patients and 0.117 in controls (p less than 0.01). The erythrocyte glutathione peroxidase activities, as mumol of NADPH oxidized/g hemoglobin/min, averaged 11.01 in patients and 31.76 in controls (p less than 0.01). Four patients exhibited myalgic symptomatology suggestive of clinical selenium deficiency. No correlations could be ascertained between plasma selenium levels and glutathione peroxidase activities in either patients or controls. Additionally, in the patient group, no significant correlations could be ascertained between selenium status and oral caloric intake, residual small bowel length, symptomatology suggestive of deficiency or HPN duration. However, since sample size was not large, lack of correlations might best be considered suggestive not conclusive. The data indicate that HPN patients with small bowel resections exhibit suboptimal selenium status and may be at risk of developing clinically evident selenium deficiency. HPN patients should be prophylactically supplemented with selenium regardless of oral intake, duration of HPN, or residual length of resected small bowel.

Dietary selenium intake in Belgium

The estimation of the dietary selenium intake in Belgium has been carried out. Average concentration levels in different food classes, as determined by hydride generation atomic absorption spectrometry are used combined with dietary consumption records or production, importation and exportation statistics. Analysis of duplicate meals has been used as an alternative evaluation method. Dietary intake of selenium in Belgium is discussed and compared with intakes published for other different countries.

Selenium and glutathione peroxidase levels in patients with epidermoid carcinoma of the oral cavity and oropharynx

Selenium ingestion may inhibit carcinogenesis. Epidemiologic studies have shown that age-adjusted death rates for cancer at most head and neck sites are lower in states where the soil and forage crops contain higher levels of selenium. The mode of action is incompletely understood, but may be mediated through an increase in the activity of the selenium dependent, antioxidant enzyme glutathione peroxidase (GSH-Px). The authors studied blood selenium levels and blood and tissue GSH-Px activities in 50 patients with untreated cancer of the oral cavity and oropharynx. Mean erythrocyte selenium and glutathione peroxidase were significantly depressed when compared to age-matched controls. Mean plasma selenium, on the other hand, was significantly elevated in the cancer patient group. Data from subsets within the cancer patient group were also discussed. GSH-Px activity did not differ in tumor and adjacent normal tissue. The concept of chemoprevention of carcinogenesis with inhibitory chemical compounds is particularly apropos to head and neck cancer control. Further work is indicated to determine if ingestion of supplemental selenium corrects the abnormalities identified here, and what affect, if any, this would have on the development and behavior of squamous cell cancers in the upper aerodigestive tract.

Clinical consequences of low selenium intake and its relationship to vitamin E

Great differences in dietary selenium intake have resulted in naturally occurring human selenium deficiencies and toxicities in certain parts of the world. Most North American diets, however, provide levels of selenium that fall within the estimated safe and adequate range of intake (50 to 200 microgram/day for adults) as established by the U.S. National Research Council. Low selenium status may develop in individuals fed certain therapeutic diets or given total parenteral nutrition. Attempts have been made to link low selenium intake with cancer and heart disease, but additional research is needed in this area. Selenium, as a constituent of glutathione peroxidase, plays a role in the antioxidant defense systems of the body, but other metabolic roles for selenium may yet be discovered.

Hematologic and selenium status of low-birth-weight infants fed formulas with and without iron

Preterm infants with birth weights between 1,001 and 1,600 gm were randomly assigned at one week of age to three groups and fed a standard milk-based formula, the same formula with iron, or a soy-based formula with iron. Hematologic values and selenium status were then studied prospectively for five weeks. Rates of decline in hematocrit and hemoglobin did not differ significantly among the three groups and did not correlate with red cell selenium values or glutathione peroxidase activity. Attainment of vitamin E sufficiency was variable among the infants, with no significant intergroup differences. Plasma selenium concentrations did not change significantly, but plasma glutathione peroxidase activity declined consistently in all three groups. Under the conditions of this study, iron at a concentration of 12 mg/L of infant formula did not accelerate hemolysis; nor was there evidence of a direct association between selenium values and early anemia of prematurity.

Selenium supplementation in total parenteral nutrition

Four adult patients with very low plasma selenium (Se) levels ( less than or equal to 1.5 microgram/100 ml) were given Se supplements while receiving total parenteral nutrition. A comparison was made using the compounds selenomethionine and sodium selenite given either intravenously or by mouth. Urinary excretion and Se plasma responses differed, and indicated that selenomethionine retention was greater. However, the incorporation of Se into the erythrocyte and its enzyme glutathione peroxidase was unpredictable and delayed and was not a good indicator of supplement response. No deleterious effects of supplements were observed. Se supplements are indicated especially in patients with a high risk of developing low Se levels and are best monitored by plasma Se levels.

Selenium: childhood poisoning and cystic fibrosis

Two cases of selenium ingestion in children are described; one child with severe cystic fibrosis died. Both children had cystic fibrosis and both had low serum chloride in association with selenium usage. Neither child was exposed to excessive heat or cold weather, factors known to salt-deplete children were cystic fibrosis, although one child was dehydrated during a summer month on initial presentation. One child had protein-calorie malnutrition, a condition known to enhance selenium toxicity in animals. We conclude that selenium is a potential hazard in its use as a health food fad for children with cystic fibrosis and in overdose ingestions. Thus selenium supplementation may have contributed to the morbidity and mortality reported here.

Selenium binding and distribution in goat and cow milk

Raw milk from goats and cows (bovine) was combined with sodium selenite (.5 muCi/10 ml milk) and incubated at 39 C to allow selenium binding to milk components. After incubation intervals between .5 and 24 h, samples were separated into cream, whey, and casein fractions by centrifugation and acid precipitation. When samples were incubated up to 6 h, the aqueous whey fraction contained the highest amounts of radioactivity, the casein substantially less, and the cream contained little senenium-75. Twenty-four hours of incubation at 39 C caused the samples to curdle, resulting in a major shift of radioactivity from the aqueous phase to the acid precipitable (casein) fraction. This shift occurred in all curdled samples irrespective of time or temperature of incubation. Acidifying milk samples with lactic acid in the presence of a bacterial inhibitor also increased selenium binding by the casein fraction. Samples of whey fractions were applied to a Sephadex gel filtration column for further separation. Most of the selenium-75 was recovered in low molecular weight fractions. Radioaactive selenium appeared to remain largely in the unbound ionic form when added to noncurdled goats' or cows' milk. Most of the selenite added to milk does not combine with proteins at normal pH but increasingly does so as pH falls below 6.0.

Selenium nutriture in total parenteral nutrition: intake levels

More attention is being given to the essential trace elements in human nutrition, although there is much to be learned concerning requirements, function, and interactions. The extensive use of total parenteral nutrition (TPN) provides an opportunity for further study. To date, little attention has been paid to selenium (Se), an element for which both a deficiency and toxic state can exist. In a program to evaluate the effects of long-term TPN on Se nutriture, a avriety of solutions used in TPN have been analyzed. Se was not present in detectable levels in the following solutions: sodium acetate, Freamine II, NaCl, potassium phosphate, KCl, Folvite, Liquaemin Na, CaCl2, MgSO4, and NaHCO3. The solutions containing significant amounts of Se were: 50% dextrose 0.27 +/- 0.04 microgram/ml and 20% dextrose 0.27 +/- 0.08 microgram/ml (Travenol Laboratories); 50% dextrose 0.47 +/- 0.10 microgram/ml and 20% dextrose 0.35 +/- 0.07 microgram/ml (Abbott Laboratories); and 70% dextrose 0.33 +/- 0.08 microgram/ml (McGaw Laboratories). These data suggest that 200 to 400 microgram Se would be provided in the usual amounts of solution administered to an adult patient.

Selenium and total parenteral nutrition

Despite the increasing recognition of selenium (Se) as an essential trace element in man, little is known about its metabolism during total parenteral nutrition (TPN) and the possible development of Se deficiency in high risk patients. From a general population known by its geographical location to have low Se blood levels, we studied a group of 23 surgical patients receiving TPN for at least one week. Whole blood Se levels were less than in the normal general population and, being some of the lowest observed in adult man, approached levels observed in animals with Se-responsive syndromes. Se continued to be lost predominantly in the urine although the Se content of the TPN fluids was very low (less than 0.6 micrograms/24 hr). Patients with excessive volumes of gastrointestinal excretion lost more Se. Se supplementation may be required in some patients receiving TPN.