The British journal of nutrition
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Current trials of immune-enhancing diets suggest several beneficial clinical effects. These products are associated with a reduction in infectious risk, ventilator days, ICU and hospital stay. However, methodological weaknesses limit the inferences we can make from these studies. ⋯ In these conditions we hypothesize that systemic inflammation might be undesirably intensified by immune-enhancing nutrients like arginine in critically ill patients. In this paper, we review the purported effects of arginine on the immune system and organ function to understand the scientific rationale for its inclusion into enteral feeding products. We conclude that patients with the most severe appearances of the systemic inflammatory response syndrome should not receive immune-enhancing substrates which may aggravate systemic inflammation and worsen clinical outcomes.
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Critically ill patients on intensive care units are at an increased risk of sepsis, which is a major cause of mortality in these patients. Recent evidence suggests that impairment of the functioning of the immune system contributes to the development of sepsis in such patients. In particular, monocytes show reduced expression of HLA-DR antigen, associated with impaired antigen presenting capability and decreased phagocytic activity; lymphocytes show decreased proliferation in response to mitogens and T-helper cells show a shift in the Th1/Th2 ratio consistent with impaired immunity. ⋯ In vivo studies have demonstrated that glutamine is essential for optimal immune cell functioning for monocytes, lymphocytes and neutrophils. A number of trials of patients fed by the enteral or parenteral route have shown improved infectious morbidity when supplemented with glutamine. However, the exact mechanism of glutamine action in these patients remains to be determined.
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The UK Department of Health recently recommended that flour be fortified with folic acid, at 2400 microg/kg. The objectives of the present paper were: to determine the consequence of this on folic acid intake of adolescents; to determine the level of fortification necessary to achieve an intake of 400 microg/d in adolescent girls (the amount recommended periconceptionally); to estimate the consequence of fortification on folic acid intake of high flour consumers; and to report on folate intake of adolescents. Dietary intake of folate and flour were determined by analysis of an existing database of the diets of 379 English adolescents. ⋯ Without flour fortification, 6.9 % of girls failed to reach the UK lower reference nutrient intake for total folate. Fortification of white flour with folic acid at 2400 microg/kg would result in an additional folic acid intake of 191(sem 6) microg/d in girls. To ensure 97 % of girls received 400 microg/d from white flour, white flour would need to be fortified at a level of 10 430 microg/kg, resulting in intakes of 1260 microg/d from flour in the highest (97.5 centile) female white flour consumers and 1422 microg/d from flour in the highest (97.5 centile) male white flour consumers.
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Comparative Study
Short- and long-term effects of calcium and exercise on bone mineral density in ovariectomized rats.
At the level of prevention of bone mineral loss produced by ovariectomy, the aim of the present study was to determine the effect produced by supplementation of Ca in the diet and a moderate exercise programme (treadmill), simultaneously or separately, in ovariectomized rats, an experimental model of postmenopausal bone loss. Female Wistar rats (n 110, 15 weeks old) were divided into five groups: (1) OVX, rats ovariectomized at 15 weeks of age, fed a standard diet; (2) SHAM, rats sham operated at 15 weeks of age, fed a standard diet; (3) OVX-EX, ovariectomized rats, fed a standard diet and performing the established exercise programme; (4) OVX-Ca, ovariectomized rats fed a diet supplemented with Ca; (5) OVX-EXCa, ovariectomized rats with the exercise programme and diet supplemented with Ca. The different treatments were initiated 1 week after ovariectomy and were continued for 13 weeks for subgroup 1 and 28 weeks for subgroup 2, to look at the interaction of age and time passed from ovariectomy on the treatments. ⋯ The exercise treatment alone was able to produce an increase in BMD with regard to OVX group only in subgroup 1 of rats (younger animals and less time from ovariectomy), but not in subgroup 2. In agreement with this, there was an increase of AP in both subgroups, lower than that observed in animals submitted to exercise plus Ca supplement, and a decrease of TRAP in subgroup 1, without significant changes in this marker in the older rats. Ca treatment did not produce any significant effect on BMD in OVX rats in both subgroups of animals, showing a decrease of AP and TRAP levels in the younger animals with no significant variations in markers of bone remodelling in the older female rats compared with their respective OVX group.
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Comparative Study
Dietary assessment in Whitehall II: comparison of 7 d diet diary and food-frequency questionnaire and validity against biomarkers.
The aim of the present cross-sectional study was to examine the agreement and disagreement between a 7 d diet diary (7DD) and a self-administered machine-readable food-frequency questionnaire (FFQ) asking about diet in the previous year, and to validate both methods with biomarkers of nutrient intake. The subjects were an age- and employment-grade-stratified random subsample of London-based civil servants (457 men and 403 women), aged 39-61 years, who completed both a 7DD and a FFQ at phase 3 follow-up (1991-1993) of the Whitehall II study. Mean daily intakes of dietary energy, total fat, saturated, monounsaturated and polyunsaturated fatty acids, linoleic acid, total carbohydrate excluding fibre, sugars, starch, dietary fibre, protein, vitamin C, vitamin E (as alpha-tocopherol equivalents), folate, carotenes (as total beta-carotene activity), Fe, Ca, Mg, K and alcohol were measured. ⋯ The two methods show satisfactory agreement, together with an expected level of systematic differences, in their estimates of nutrient intake. Against the available biomarkers, the machine-readable FFQ performed well in comparison with the manually coded 7DD in this study population. For both methods, regression-based adjustment of nutrient intake to mean dietary energy intake by gender appears on balance to be the optimal approach to data presentation and analysis, in view of the complex problem of low energy reporting.