The American journal of clinical nutrition
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This report addresses the current controversy about possible health hazards of dietary trans fatty acid isomers, which are created during hydrogenation of unsaturated fats to change their textural properties and melting points. Estimates of intakes are approximations based on limited data and problematic analytic techniques. Major contributors in the diet are fried and baked foods and margarine, in which partially hydrogenated vegetable oils may replace fat sources richer in saturated fatty acids and cholesterol. ⋯ The nutrition labeling issue is unresolved. The options, recommendations, and research suggestions in this report should outline for nutrition scientists the database needed before any new dietary recommendations or changes in nutrition policy concerning trans fatty acids can be made. The debate about trans fatty acids should not detract from dietary recommendations to limit the intake of saturated fat and total fat.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intestinal calcium absorption of women during lactation and after weaning.
We investigated whether intestinal calcium absorption and serum 1,25-dihydroxycholecalciferol (calcitriol) concentrations are higher in women during lactation and after weaning to compensate for calcium lost in breast milk. Measurements were obtained at 4.6 mo postpartum in 24 lactating women and 24 nonlactating women, at 9.6 mo postpartum in 24 lactating women (2.6 mo after complete weaning) and 24 nonlactating women. One-half of the women in each group were randomly assigned to receive 1 g supplemental Ca/d as calcium carbonate. ⋯ Lactating women who had resumed menses had higher fractional absorption and serum calcitriol than did lactating women who had not. Serum calcium and phosphorus concentrations were greater in lactating compared with nonlactating women; there were no differences between groups after weaning. We conclude that lactation stimulates increases in fractional calcium absorption and serum calcitriol, but the responses are only apparent after weaning or the resumption of menses.
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Dienoic eicosanoids derived from phospholipid arachidonic acid (AA) in lung and liver macrophages promote leukosequestration, thrombosis, and tissue injury. Current enteral diets (diet A) are enriched with linoleic acid (LA), a precursor of AA. Novel diets low in LA and containing eicosapentaenoic acid (EPA) and gamma-linolenic acid (GLA) foster formation of less inflammatory eicosanoids. ⋯ Incorporation of dihomo-gamma-linolenic acid (DHGLA), the metabolite of GLA, into lung and KE phospholipids was significant in rats given diet C. Most of the changes in fatty acid composition occurred by day 3. The polyunsaturated fatty acid composition of AM phi, lung, and KE cell phospholipids can be rapidly modified by continuous short-term enteral feeding with EPA- and GLA-enriched diets irrespective of concurrent endotoxemia.
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We tested the hypothesis that an intramuscular relative dose response (IM-RDR) on day 1 of life would more accurately predict which premature infants would develop bronchopulmonary dysplasia (BPD) than single measurements of retinol, retinyl palmitate (RP), or retinol binding protein (RBP). Seventy-five premature infants < or = 32 wk gestation had the IM-RDR on day 1 of life. An RDR > or = 25% occurred in 6 of 37 infants who did not develop BPD compared with 15 of 38 infants who developed BPD (P = 0.025). ⋯ RP values at time 0 and 5 h on day 28 were higher than day 1 values in both infants without BPD and infants with BPD who did not receive dexamethasone. Retrospective analysis also revealed a significant correlation between a day-1 RDR > or = 25% and the incidence of intraventricular hemorrhage in these premature infants. Because the IM-RDR is more helpful in predicting the development of BPD than single serum retinol and RP analyses, this test could be useful in determining which premature infants might benefit from supplemental vitamin A for BPD.
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Plasma fluxes of arginine, citrulline, and leucine, and the rate of conversion of labeled citrulline to arginine (Qcit-->arg) were determined in nine severely burned patients (mean: 56% body surface burn area, mean 10 d postinjury) while they received total parenteral nutrition (TPN) including an L-amino acid mixture that supplied a generous amount of nitrogen (mean: 0.39 +/- 0.02 g.kg-1.d-1). Plasma fluxes were also studied in these patients during a basal state (low-dose intravenous glucose) by using a primed, 4-h constant intravenous tracer-infusion protocol. Stable-nuclide labeled tracers were L-[15N-15N-guanidino,5,5,2H2]arginine; L-[13C-ureido]citrulline; L-[1-13C]leucine; and NaH13CO3 (prime only), with blood and expired air samples drawn at intervals to determine isotopic abundance of arginine, citrulline, ornithine, and alpha-ketoisocaproate (KIC; for leucine) in plasma and 13CO2 in breath. ⋯ The plasma arginine fluxes were correspondingly higher in burn patients than in healthy control subjects. However, the citrulline flux and rate of conversion of citrulline to arginine were not higher than values obtained in our laboratories in healthy adult subjects. We hypothesize that the higher rates of arginine loss from the body after burn injury would need to be balanced by an appropriate exogenous intake of preformed arginine to maintain protein homeostasis and promote recovery from this catabolic condition.