TOP NUTRITION NEWSLETTER VOLUME 2, NO 11:NOVEMBER 1999 Editorial This is the eleventh issue of TOP
NUTRITION NEWSLETTER in 1999. In this issue the following topics are updated for
your interest.
Any comments or suggestions to
include the interesting topics are welcomed for future issues.
Dr Shwe Win Editor
DESIGN: Prospective, multicentered, double-blind, randomized controlled trial. SETTING: Intensive care units of five academic and teaching hospitals in the United States. PATIENTS: We
enrolled 146 patients with ARDS (as defined by the American-European Consensus
Conference) caused by sepsis/pneumonia, trauma, or aspiration injury in the study.
INTERVENTIONS: Patients meeting entry criteria were randomized and continuously
tube-fed either EPA+GLA or an isonitrogenous, isocaloric standard diet at a minimum
caloric delivery of 75% of basal energy expenditure x 1.3 for at least 4-7 days.
MEASUREMENTS AND MAIN RESULTS: Arterial blood gases were measured, and
ventilator settings were recorded at baseline and study days 4 and 7 to enable calculation
of PaO2/FIO2, a measure of gas exchange. Pulmonary neutrophil recruitment was
assessed by measuring the number of neutrophils and the total cell count in bronchoalveolar lavage fluid at the same time points. Clinical outcomes were recorded.Baseline characteristics of 98 evaluable patients revealed that key demographic,
physiologic, and ventilatory variables were similar at entry between both groups. Multiple
bronchoalveolar lavages revealed significant decreases (approximately 2.5-fold) in the
number of total cells and neutrophils per mL of recovered lavage fluid during the study with
EPA+GLA compared with patients fed the control diet. Significant improvements in
oxygenation (PaO2/FIO2) from baseline to study days 4 and 7 with lower ventilation
variables (FIO2, positive end-expiratory pressure, and minute ventilation) occurred in
patients fed EPA+GLA compared with controls. Patients fed EPA+GLA required
The influence of
low intake of n-3 fatty acids on platelets in elderly people
A total of ten healthy elderly subjects ingested one capsule of 600 mg (corresponding to 150 mg docosahexaenoic acid and 30 mg eicosapentaenoic acid) RO-PUFA triglycerides per day and ten others ingested one capsule of 600 mg sunflower oil as a placebo for 42 days. In the n-3 polyunsaturated fatty acids (PUFA) group, a significant decrease of systolic blood pressure was observed, as well as a trend towards a decrease in both platelet activation and basal formation of thromboxane B2. Also, a slight but significant increase of docosahexaenoic acid was observed in the phosphatidylethanolamine fraction as well as a significant increase of vitamin E level after the n-3 PUFA intake. Moreover, the basal production of malondialdehyde significantly decreased. No modification was observed for all these parameters in the placebo group. We conclude that a small intake of n-3 PUFA decreased the oxidative stress in platelets of elderly people and could be beneficial in subjects with atherothrombotic tendencies by lowering the cell peroxide tone. DiscussionThe choice of the low dosage used in this randomized, double blind study, was based on studies investigating n-3 PUFA and aging. Indeed, increased platelet activation and lipid peroxidation associated with a decreased platelet antioxidant status have been reported in elderly people. On the other hand, a supplementation of the western diet with n-3 PUFA exerts an effect that is generally considered as beneficial towards the risk of developing cardiovascular diseases. However, high doses of these fatty acids both increase the degree of unsaturation in membrane phospholipids and the susceptibility to lipid peroxidation , and thus potentially lead to an increased risk for atherosclerosis to the detriment of beneficial effects. Considering all these results, our approach was to give small amounts of n-3 PUFA to elderly people to see whether potential beneficial effects could be observed. In terms of blood pressure, the antihypertensive effect of n-3 PUFA both on diastolic and systolic pressures has been shown with high doses. Interestingly, we found in the present study that even at a low supplementation, n-3 PUFA was effective on systolic blood pressure, which agrees with previous results of decreased blood pressure after an intake of similar doses of EPA . However no modification appeared in diastolic blood pressure, in agreement with previous observations showing that systolic pressure decreased earlier than diastolic pressure after supplementation. Thus, the unchanged diastolic pressure may be due in part to the short span of the study period. In general, the tendency of platelets to aggregate in response to different agonists is significantly lowered after dietary intake of n-3 PUFA and might be explained by the enrichment of membrane phospholipids with EPA and DHA at the expense of AA. However, it has been shown that incorporation of n-3 PUFA in platelet phospholipids may not be required for inhibition of platelet aggregation to occur. In agreement with this finding, low supplementations of EPA in elderly people significantly decreased platelet aggregation without modification of phospholipid composition . In the present study, a modest change in platelet aggregation was observed but with a trend of less aggregation. This difference could be due to DHA, less potent than EPA in inhibiting in vitro platelet aggregation, at least with moderate intake . Nevertheless, dietary RO-PUFA induced a small but significant incorporation of DHA in a particular phospholipid, the phosphatidylethanolamine (PE) fraction, and this result is consistent with observations from Aukema and Holub and Croset et al. These authors demonstrated that DHA is preferentially incorporated in alkenylacyl PE in human platelets, which could decrease platelet reactivity. Moreover, plasmalogen phospholipids could act as scavengers of peroxyl radicals in the lipid environment. This contention is in accordance with our findings concerning lipid peroxidation. Indeed, a marked reduction in lipid peroxidation was observed as measured by MDA, a marker of the overall lipid peroxidation. These findings are of particular interest in elderly people who could be considered as an oxidatively stressed population . In such a population, a low intake of n-3 PUFA would not increase lipid peroxidation as observed with high doses , but would protect cells against oxidative damage. A reduction of MDA production has already been reported after fish oil supplementation in patients suffering from hyperlipidemia and in psoriatic patients. However in the two latter studies, stimulation of platelet GSH-Px has been shown to compensate for the increment of lipoperoxides. In the present study, this mechanism is unlikely to occur since neither the activity nor the quantity of GSH-Px was changed in platelets after RO-PUFA intake. Interestingly, alpha- and gamma-tocopherol levels were enhanced in platelets from the RO-PUFA group, the highest increase concerning gamma-tocopherol as already reported with a low intake of EPA Among vitamin E isomers, alpha-tocopherol is considered to be the most important antioxidant with the highest bioactivity, but gamma-tocopherol could have biological significance in some situations. Indeed, differences in certain chemical reactivities between alpha- and gamma-tocopherols have been described regarding their reaction with nitrogen dioxide, which could explain why gamma-tocopherol might be more potent than alpha-tocopherol against some peroxidative reactions. Although some epidemiologic studies clearly indicate that a low intake of fish may beneficially influence coronary heart diseases, few data are available from experimental studies on low intake of n-3 PUFA. The present study demonstrates that in a particular population such as elderly people, low intake of n-3 PUFA could induce beneficial effects in terms of blood pressure and platelet activation. Moreover, the cellular peroxide tone decreased and the antioxidant status increased. We conclude that a modest supplementation of n-3 PUFA could be beneficial, particularly in populations with atherothrombotic tendencies.
Reference: JPEN 1999;23:S59-S61. ABSTRACT: New strategies for immunonutritional support include administration of special nutrients such as glutamine. Glutamine is important in several
key metabolic processes of immune cells and enterocytes. Exogenous glutamine augments the functions of lymphocytes and macrophages.
Neutrophils also reportedly utilize glutamine at a significant rate. Our recent studies demonstrated that glutamine enhances neutrophil
function. This article focuses on the effects of glutamine on neutrophil function in surgical stress. Enteral glutamine administration enhanced
peritoneal and hepatic bacterial clearance in our rat peritonitis model. Furthermore, IV glutamine supplementation improved the outcome of
animals with severe surgical stress. Our in vitro study revealed that supplemental glutamine augmented the bacterial killing function of
neutrophils from postoperative patients. Glutamine increased phagocytosis of the neutrophils. In addition, glutamine dose-dependently
increased production of reactive oxygen intermediates (ROI) by neutrophils. Thus, our studies suggest that glutamine supplementation may
improve bactericidal function of neutrophils by increasing both phagocytosis and ROI production. In conclusion, glutamine plays an
important role in neutrophil function. Glutamine may be useful for the prevention, and treatment, of severe infection in critical illness and
trauma.
Postoperative nitrogen sparing refers to a therapy that decreases net nitrogen loss from the body following an operation. Protein sparing has
long been regarded as a surrogate marker for improved outcome, but a critical review of the evidence indicates that this relation is difficult to
establish, especially in the short term. Thus, specific endpoints that evaluate outcome are needed to determine the efficacy of a specific
therapy that spares protein. Cost effectiveness must also be considered. A variety of therapies were evaluated using protein-sparing, |
EPA
+ GLA + antioxidants in ARDS patients