Nutrient reference value: non-communicable disease endpoints--a conference report.

Nutrition is complex-and seemingly getting more complicated. Most consumers are familiar with "essential nutrients," e.g., vitamins and minerals, and more recently protein and important amino acids. These essential nutrients have nutrient reference values, referred to as dietary reference intakes (DRIs) developed by consensus committees of scientific experts convened by the Institute of Medicine of the National Academy of Sciences, Engineering, and Medicine and carried out by the Food and Nutrition Board. The DRIs comprise a set of four nutrient-based reverence values, the estimated average requirements, the recommended dietary allowances (RDAs), the adequate intakes and the tolerable upper intake levels for micronutrient intakes and an acceptable macronutrient distribution range for macronutrient intakes. From the RDA, the US Food and Drug Administration (FDA) derives a labeling value called the daily value (DV), which appears on the nutrition label of all foods for sale in the US. The DRI reports do not make recommendations about whether the DV labeling values can be set only for what have been defined to date as "essential nutrients." For example, the FDA set a labeling value for "dietary fiber" without having the DV. Nutrient reference values-requirements are set by Codex Alimentarius for essential nutrients, and regulatory bodies in many countries use these Codex values in setting national policy for recommended dietary intakes. However, the focus of this conference is not on essential nutrients, but on the "nonessential nutrients," also termed dietary bioactive components. They can be defined as "Constituents in foods or dietary supplements, other than those needed to meet basic human nutritional needs, which are responsible for changes in health status (Office of Disease Prevention and Health Promotion, Office of Public Health and Science, Department of Health and Human Services in Fed Regist 69:55821-55822, 2004)." Substantial and often persuasive scientific evidence does exist to confirm a relationship between the intake of a specific bioactive constituent and enhanced health conditions or reduced risk of a chronic disease. Further, research on the putative mechanisms of action of various classes of bioactives is supported by national and pan-national government agencies, and academic institutions, as well as functional food and dietary supplement manufacturers. Consumers are becoming educated and are seeking to purchase products containing bioactives, yet there is no evaluative process in place to let the public know how strong the science is behind the benefits or the quantitative amounts needed to achieve these beneficial health effects or to avoid exceeding the upper level (UL). When one lacks an essential nutrient, overt deficiency with concomitant physiological determents and eventually death are expected. The absence of bioactive substances from the diet results in suboptimal health, e.g., poor cellular and/or physiological function, which is relative and not absolute. Regrettably at this time, there is no DRI process to evaluate bioactives, although a recent workshop convened by the National Institutes of Health (Options for Consideration of Chronic Disease Endpoints for Dietary Reference Intakes (DRIs); March 10-11, 2015; http://health.gov/dietaryguidelines/dri/ ) did explore the process to develop DVs for nutrients, the lack of which result in increased risk of chronic disease (non-communicable disease) endpoints. A final report is expected soon. This conference (CRN-International Scientific Symposium; "Nutrient Reference Value-Non-Communicable Disease (NRV-NCD) Endpoints," 20 November in Kronberg, Germany; http://www.crn-i.ch/2015symposium/ ) explores concepts related to the Codex NRV process, the public health opportunities in setting NRVs for bioactive constituents, and further research and details on the specific class of bioactives, n-3 long-chain polyunsaturated fatty acids (also termed omega-3 fatty acids) and their constituents, specifically docosahexaenoic acid and eicosapentaenoic acid.

Antioxidant status and biomarkers of oxidative stress in dogs with lymphoma.

BACKGROUND: Oxidative stress might play a role in carcinogenesis, as well as impacting morbidity and mortality of veterinary cancer patients. The purpose of this study was to evaluate antioxidant concentrations and biomarkers of oxidative stress in dogs with newly diagnosed lymphoma before treatment and once in remission, with comparison with healthy controls. HYPOTHESIS: Dogs with lymphoma have increased oxidant and reduced antioxidant concentrations compared with healthy controls, and that these abnormalities normalize once remission is achieved. ANIMALS: Seventeen dogs with lymphoma and 10 healthy controls. METHODS: Prospective, observational study. Measures of oxidative stress [malondialdehyde and total isoprostanes (isoP)] and antioxidants [alpha-tocopherol, gamma-tocopherol, oxygen radical absorbance capacity (ORAC), and glutathione peroxidase (GSHPx)] were assessed in dogs with newly diagnosed lymphoma before treatment compared with healthy control dogs. The same parameters were measured in the dogs with lymphoma on week 7 of the chemotherapy protocol when all dogs were in remission. RESULTS: At baseline, dogs with lymphoma had significantly lower alpha-tocopherol (P <.001) and gamma-tocopherol (P= .003) but higher GSHPx (P= .05), ORAC (P= .001), and isoP (P < .001) compared with healthy controls. In the dogs with lymphoma, alpha-tocopherol concentrations were higher (P= .005) and ascorbic acid were lower (P= .04) after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Results suggest that dogs with lymphoma have alterations in oxidant and antioxidant concentrations and that the status of some of these biomarkers normalize after remission. Further studies are warranted to determine whether antioxidant interventions to correct these are beneficial in the treatment of canine lymphoma.

Effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure.

OBJECTIVE: To assess the effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate homeostasis and biomarkers of oxidative stress. DESIGN: A randomized, double-blind, controlled clinical trial. SETTING: The trial was conducted at two clinics. SUBJECTS AND INTERVENTIONS: Ninety-seven men and women with resting systolic blood pressure 130-179 mm Hg and/or diastolic blood pressure 85-109 mm Hg were randomly assigned to consume foods containing oat beta-glucan or control foods for 12 weeks. Resting blood pressures, insulin and glucose values before and after standard breakfast meals, and four biomarkers of oxidative stress were measured before and at the end of the treatment period. RESULTS: Changes from baseline to week 12 in mean peak insulin and incremental area under the insulin curve differed significantly between groups (P=0.037 and 0.034, respectively), with the beta-glucan group showing declines and the control group remaining essentially unchanged. Blood pressure responses were not significantly different between groups overall. However, in subjects with body mass index above the median (31.5 kg/m(2)), both systolic (8.3 mm Hg, P=0.008) and diastolic (3.9 mm Hg, P=0.018) blood pressures were lowered in the beta-glucan group compared to controls. No significant differences in biomarkers of oxidative stress were observed between treatments. CONCLUSIONS: The results of the present trial suggest beneficial effects of foods containing beta-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects.

Regulation of GATA-4 and AP-1 in transgenic mice overexpressing cardiac calsequestrin.

Transgenic mouse hearts overexpressing the Ca(2+)-binding protein calsequestrin (CSQ) have an accompanying 10-fold increase in the sarcoplasmic reticulum (SR) Ca2+ load, however, exhibits slow and small Ca(2+)-induced Ca2+ release. Such slow kinetics of Ca2+ release may have activated excitation-transcription coupling as CSQ overexpressing hearts have induced levels of NFAT and GATA-4 activities and higher levels of c-fos mRNA and cFos protein compared to those of non-transgenic littermates. Adaptive responses, however, appear to downregulate transcriptional regulators controlling c-fos gene including serum response factor and Ca2+/cAMP response element-binding protein. CSQ-overexpressing hearts also had decreased levels of cJun protein, resulting in downregulated AP-1 activity. The mRNA levels of angiotensin II type1a receptor which requires AP-1 and GATA-4 for gene transcription was suppressed in CSQ overexpressing hearts. These results demonstrate that CSQ can regulate GATA-4- and AP-1-dependent transcriptional events, indicating the existence of SR-nuclear circuits of signal transduction in adult cardiac muscle.

Effect of vitamin E on hydrogen peroxide production by human vascular endothelial cells after hypoxia/reoxygenation.

Changes in oxidative stress status play an important role in tissue injury associated with ischemia -- reperfusion events such as those that occur during stroke and myocardial infarction. Endothelial cells (EC) from human saphenous vein and aorta were incubated for 22 h and found to take up vitamin E from media containing 0-60 mM vitamin E in a dose-dependent manner. EC supplemented with 23 or 28 mM vitamin E in the media for 22 h were maintained at normoxia (20% O2, 5% CO2, and balance N2) or exposed to hypoxic conditions (3% O2, 5% CO2, and balance N2) for 12 h, followed by reoxygenation (20% O2) for 30 min. Saphenous EC supplemented with 23 mM vitamin E produced less (p < 0.05) H2O2 than unsupplemented controls, both at normoxic condition (supplemented: 4.9 +/- 0.05 vs. control: 10.9 +/- 1.3 pmol/min/10(6) cells) and following hypoxia/reoxygenation (supplemented: 6.4 +/- 0.78 vs. control: 17.0 +/- 2.7 nmol/min/10(6) cells). In contrast, aortic EC, which were found to have higher superoxide dismutase and catalase activity than EC from saphenous vein, did not produce any detectable levels of H2O2. Following hypoxia/reoxygenation, the concentration of vitamin E in supplemented saphenous EC was 62% lower than cells maintained at normoxia (0.19 +/- 0.03 vs. 0.5 +/- 0.12 nmoles/10(6) cells, p < 0.001); in aortic EC vitamin E content was reduced by 18% following reoxygenation (0.86 +/- 0.16 vs. 0.70 +/- 0.09 nmoles/10(6) cells, p < 0.05). Therefore, enrichment of vitamin E in EC decreases H2O2 production and thus may reduce the injury associated with ischemia-reperfusion events.

Effect of vitamin E on human aortic endothelial cell responses to oxidative injury.

Reactive oxygen species produced by the cells present in the arterial wall may cause oxidative damage to cellular components altering endothelial cell (EC) function. Changes in the EC function appear to play a key role in the pathogenesis of atherosclerosis. Human aortic endothelial cells (HAEC) were employed to investigate the protective role of vitamin E upon exposure of endothelial cells to oxidative stress in vitro. HAEC assimilate d-alpha-tocopherol from the media in a dose-dependent manner. Exposure of HAEC to 16.5 mM of the free radical generator 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH) for 16 h decreased cell viability (assessed by trypan blue exclusion) from 90 to 28%. HAEC preincubated with vitamin E at 15, 30, and 60 microM prior to the AAPH exposure resulted in a dose-dependent increase in resistance to oxidative stress and increased cell viability by 37, 66, and 85%, respectively. An increase in prostacyclin (PGI2) production by HAEC in response to AAPH exposure was correlated positively with cell damage and negatively with vitamin E concentration. Interleukin (IL)-1 production also increased in parallel with cell damage induced by AAPH. Vitamin E treatment significantly reduced IL-1 production after AAPH exposure. This modulatory role of vitamin E on HAEC function following exposure to an oxidative stress may reflect its antioxidant protection against lipid peroxidation.

Homocysteine exerts cell type-specific inhibition of AP-1 transcription factor.

Homocysteine (Hcy) exerts either promoting or suppressive effects on mitogenesis in a cell type-specific manner. Hcy elicits proliferation of vascular smooth muscle cells, but is rather inhibitory to growth of endothelial cells and NIH/3T3 cells. In NIH/3T3 cells, we found that physiologically relevant concentrations (20-100 microM) of Hcy inhibit the activity of activating protein-1 (AP-1) transcription factor, although it is capable of eliciting immediate-early signaling events. Hcy induced p44/42 mitogen-activated protein kinase (MAPK) phosphorylation in control cells, but not in dominant negative p21ras transfected cells, indicating induction of the Ras-MAPK pathway. Hcy also induced the activity of serum response factor and expression of c-fos and c-jun genes. Despite the activation of these upstream events, Hcy potently inhibited AP-1 activity. Oxidized forms of Hcy (Hcy thiolactone, homocystine) were less effective in affecting AP-1. Hcy-mediated inhibition of AP-1 activity was not observed in A7r5 vascular smooth muscle cells. These results demonstrate that Hcy exerts cell type- and redox-specific inhibition of AP-1 dependent biological events.

Relative reactivity of lysine and other peptide-bound amino acids to oxidation by hypochlorite.

Antibacterial and inflammatory responses of neutrophils and macrophages produce hypochlorite as a major oxidant. Numerous side chains of amino acids found in extracellular proteins can be modified by hypochlorite, including His, Arg, Tyr, Lys, Trp, and Met. We studied the relative reactivity of each of these amino acid residues in short N-blocked peptides, where other residues in the peptide were highly resistant to hypochlorite attack. Hypochlorite treatment led to modified peptides in each case, which were detected by changes in retention on reversed-phase HPLC. A distinct single product, consuming two equivalents of hypochlorite per equivalent of peptide, was obtained from the Lys-containing peptides. UV spectroscopy, nuclear magnetic resonance (NMR), and electrospray/mass spectroscopy identified this product as the dichloramine at the epsilon-amino group of the Lys side chain. The dichloramine at Lys did not decompose to form a detectable amount of carbonyl reactive with dinitrophenylhydrazine. The dichloramine at Lys did however quantitatively revert back to Lys during HCl digestion of the tetrapeptide for amino acid analysis, with simultaneous modification of the adjacent Phe residue. The formation of the dichloramine at Lys was not blocked by peptides or acetylated amino acids that contained Tyr, His, or Arg. In contrast, the presence of equimolar Met-containing peptide, or N-Acetyl-Trp, both inhibited the formation of the dichloramine at Lys. Thus, Met and Trp side chains of proteins might be able to protect Lys from chloramine formation under some circumstances, but this interpretation must consider that Met and Trp are typically found in relatively inaccessible hydrophobic sites, whereas lysine is typically exposed on the protein surface. The hierarchy of amino acid reactivities examined here will aid in the prediction of residues in biological samples most likely to be modified by hypochlorite.

Modulation of angiotensin II signaling for GATA4 activation by homocysteine.

Homocysteine (Hcy) is a redox active thiol-containing compound with pro-oxidant and pathogenic properties in the cardiovascular system. Angiotensin II (Ang II) also plays important roles in age-associated cardiovascular disease. Recently, the GATA4 transcription factor was recognized as a mediator of heart failure. We investigated the interrelationship of these elements in NIH/3T3 fibroblasts and found that Ang II induces GATA4 activity and Hcy alters Ang II signaling. Electrophoretic mobility shift assays determined that treatment of cells with Ang II induced DNA binding activity to the GATA consensus sequence. This activation was transient with a peak occurring at 30 min. Supershift analysis revealed the GATA binding protein as GATA4. Ang II also induced NFAT activity with similar kinetics. Pretreatment of cells with Hcy (100 microM) delayed the peak of Ang II-induced NFAT and GATA activation to 60 min. Ang II-mediated activation of c-fos serum response factor (SRF) was similarly delayed by Hcy. These results suggest the pathogenic mechanism of Hcy action may be mediated in part via modulation of Ang II-signaling for gene transcription.

Homocysteine and alpha-lipoic acid regulate p44/42 MAP kinase phosphorylation in NIH/3T3 cells.

Biological thiols can regulate cell signal transduction. The effects of two biothiols, homocysteine (Hcy), a risk factor for cardiovascular disease, and alpha-lipoic acid (alphaLA), a therapeutic antioxidant, on p44/42 mitogen-activated protein kinases (MAPK) phosphorylation were examined in NIH/3T3 fibroblasts. Cells grown in serum-containing media had constitutive levels of MAPK phosphorylation as determined by Western blot analysis using the phospho-specific MAPK antibody. Treatment of cells with 20 microM Hcy for 0-60 min resulted in a transient enhancement of MAPK phosphorylation. In contrast, 20 microM alphaLA inhibited serum-mediated phosphorylation of MAPK. The differential effects of these two thiols are not due to their redox states as oxidized Hcy (Hcy thiolactone) enhanced MAPK phosphorylation. The effect of alphaLA appears to be serum-dependent because Hcy or alphaLA treatment of serum-deprived cells activated MAPK phosphorylation. Thus, alphaLA and Hcy can either induce common signal transduction pathways or differentially modulate MAPK phosphorylation, depending on the state of the cell. This relationship may be important to understand how some biothiols are associated with pathogenic events while others offer potential as therapeutic agents.

Effects of thiol antioxidants on hepatocyte growth factor signaling in cardiac myocytes.

We describe here novel antioxidant-sensitive events in which activation kinetics are delayed, leading to inhibition of cell signaling. Hepatocyte growth factor (HGF) transiently phosphorylated p44/42 mitogen-activated protein kinase (MAPK) with a peak at 3-5 min in HL-1 adult cardiac myocytes. Pretreatment of cells with thiol antioxidants, N-acetylcysteine or alpha-lipoic acid attenuated MAPK phosphorylation induced by a 3-min incubation with HGF. However, kinetic analysis revealed that the apparent inhibition of HGF signaling was due to a delay in the activation because HGF phosphorylated MAPK with a peak at 5-7 min in cells treated with thiol antioxidants. This 2-min delay in HGF activation of MAPK resulted in >5-min delay in phosphorylation of MAPK targets such as p90RSK and GATA-4. Hydrogen peroxide did not mimic HGF signaling, and HGF did not induce reactive oxygen species production. Thus, in cardiac myocytes, thiol antioxidants delay HGF-mediated MAPK activation and suppress subsequent signaling eventsvia reactive oxygen species-independent mechanism.

Considerations of the scientific substantiation for antioxidant vitamins and beta-carotene in disease prevention.

Advances in our knowledge about the role vitamin C, vitamin E, and beta-carotene may play in reducing the risk of chronic diseases have been derived concomitantly from several different research approaches, each with its own advantages and limitations. Evaluation of the evidence for potential health benefits of antioxidant nutrients should include the entire spectrum of available scientific evidence--from cell biology, animal studies, clinical trials, and epidemiologic surveys--and consider the quality, strength, consistency, and biological plausibility of this evidence. However, difficult questions arise when considering how strong the correlation should be between the totality of evidence and the conclusions drawn for making individual and public health recommendations. Many of these questions address the need for additional research not only directed to the efficacy and safety of these nutrients but to their bioavailability, interactions with one another and other dietary factors, mechanisms of action, and methods to assess their functional status.

Photon activation analysis as a new technique for body composition studies.

A study was undertaken to demonstrate the usefulness of the recently developed photon activation analysis (PAA) technique for in vivo body composition studies. PAA can be used for direct measurement of total-body oxygen, nitrogen, and carbon. Sequential measurements were made on rats fed diets of 0%, 4.2%, or 20% protein for 6 1/2 wk, and significant changes in body composition were noted. In addition, rats of different ages, strains, nutritional states, and degrees of obesity were included in a comparison of PAA results in vivo with results from chemical analysis after sacrifice of the animals. High positive correlations were found between PAA measurements of carbon and chemical analysis measurements of fat and between PAA measurements of oxygen and chemical analysis measurements of total-body water. A low positive correlation was found between PAA measurements of nitrogen and chemical analysis measurements of protein.

Influence of combined antioxidant nutrient intakes on their plasma concentrations in an elderly population.

Data from a cross-sectional survey of 746 non-institutionalized, Boston-area elderly individuals (aged > or = 60 y) were analyzed to assess the relation between antioxidant nutrient intake and plasma antioxidant status. Intakes of vitamin C and carotenoids and supplemental vitamin E were estimated by using 3-d diet records. Mean plasma concentrations of these nutrients were calculated within categories of intake, and polynomial contrasts were used to test for linear trends of the plasma nutrient concentrations across these categories. Adjustments for the corresponding intake of the plasma nutrient under consideration, as well as age, sex, and smoking status were made to minimize potential confounding. Plasma alpha-tocopherol concentrations were 18% greater in individuals consuming > or = 220 mg vitamin C/d compared with those with intakes < 120 mg/d (P for trend < 0.001). Plasma carotenoid concentrations were 13% higher across increasing categories of vitamin C intake (P for trend = 0.002). An increasing intake of carotenoids was moderately associated with higher plasma alpha-tocopherol (P for trend = 0.008) and unrelated to ascorbic acid status. An increasing intake of supplemental vitamin E was weakly correlated with plasma ascorbic acid (P for trend = 0.05) and unrelated to carotenoid status. These results provide epidemiologic evidence that increasing intake of either vitamin C, vitamin E, or carotenoids is associated with greater plasma concentrations of one or both of the other antioxidant vitamins and not associated with any impairment in antioxidant status.

Assessment of the safety of high-dose, short-term supplementation with vitamin E in healthy older adults.

The effect of daily supplementation of 800 mg dl alpha-tocopheryl acetate for 30 d on general health, nutrient status, hepatic and renal function, intermediary metabolism, hematological status, plasma nutrients and antioxidant status, thyroid hormones, and urinary creatinine concentrations was studied in 32 healthy elderly (> 60 y) people who participated in a double-blind, placebo-controlled, residential trial. The subjects reported no side effects due to the supplements. Supplementation had no effect on body weight, plasma total protein, albumin, glucose, total cholesterol and triglycerides, conjugated and unconjugated bilirubin, alkaline phosphatase, indicators of hepatic and renal function, hematologic status, thyroid hormones, or serum and urinary creatinine concentrations and creatinine clearance. Supplementation did cause a significant increase in serum vitamin E, and a small (5%) but significant (P < 0.05) increase in plasma zinc in the vitamin E-supplemented group. Thus, short-term supplementation with 800 mg vitamin E/d has no adverse effect on healthy older adults.

Lutein and zeaxanthin concentrations in plasma after dietary supplementation with egg yolk.

BACKGROUND: The food matrix in which carotenoids are found affects their bioavailability. Lutein and zeaxanthin are abundant in egg yolks and accumulate in the macular region of the retina, where they may affect visual function. OBJECTIVE: We sought to determine whether plasma lutein and zeaxanthin concentrations are elevated after dietary supplementation with egg yolk. DESIGN: Eleven moderately hypercholesterolemic men and women consumed 2 separate baseline diets, which contained 29-33% of energy as total fat, with 20% of energy as either beef tallow or corn oil. These diets were supplemented with cooked chicken egg yolks (1.3 egg yolks/d for an intake of 10.4 MJ). Each subject consumed all 4 diets. Each diet was consumed for 4.5 wk, with a washout period of >/=2 wk between diet phases. At the end of each diet phase, fasting morning plasma samples were collected and stored for carotenoid analysis by HPLC. Commercial chicken egg yolks were analyzed for carotenoids and cholesterol. RESULTS: Egg yolk supplementation of the beef tallow diet increased plasma lutein by 28% (P < 0.05) and zeaxanthin by 142% (P < 0.001); supplementation of the corn oil diet increased plasma lutein by 50% (P < 0.05) and zeaxanthin by 114% (P < 0.001). Changes in plasma lycopene and beta-carotene were variable, with no consistent trend. Egg yolk supplementation increased plasma LDL-cholesterol concentrations by 8-11% (P < 0.05). CONCLUSIONS: Egg yolk is a highly bioavailable source of lutein and zeaxanthin. The benefit of introducing these carotenoids into the diet with egg yolk is counterbalanced by potential LDL-cholesterol elevation from the added dietary cholesterol.

Effect of dietary supplementation with black currant seed oil on the immune response of healthy elderly subjects.

BACKGROUND: We have shown that the age-associated increase in prostaglandin E(2) production contributes to the decline in T cell-mediated function with age. Black currant seed oil (BCSO), rich in both gamma-linolenic (18:3n-6) and alpha-linolenic (18:3n-3) acids, has been shown to modulate membrane lipid composition and eicosanoid production. OBJECTIVE: Our objectives were to 1) test whether dietary supplementation with BCSO can improve the immune response of healthy elderly subjects, and 2) determine whether the altered immune response is mediated by a change in the factors closely associated with T cell activation. DESIGN: A randomized, double-blind, placebo-controlled (soybean oil) study was conducted to examine the effect of 2 mo of BCSO supplementation on the immune response of 40 healthy subjects aged >/=65 y. In vivo immune function was determined by delayed-type hypersensitivity skin response. Peripheral blood mononuclear cells (PBMCs) were tested for in vitro immune response. RESULTS: In subjects supplemented with BCSO, the total diameter of induration at 24 h and individual responses to tetanus toxoid and Trichophyton mentagrophytes were significantly higher than their baseline values. The change in response to tetanus toxoid was significantly different from that of the placebo group. The BCSO group showed a significant increase in proliferative response of PBMCs to the T cell mitogen phytohemagglutinin that was not significantly different from that observed in the placebo group. BCSO had no effect on concanavalin A-induced mitogenic response, interleukin 2 and -1beta production, and PBMC membrane fluidity. Prostaglandin E(2) production was significantly reduced in the BCSO-supplemented group, and this change was significantly different from that of the placebo group. CONCLUSION: BCSO has a moderate immune-enhancing effect attributable to its ability to reduce prostaglandin E(2) production.

Assessment of the safety of supplementation with different amounts of vitamin E in healthy older adults.

We showed previously that supplementation for 30 d with 800 IU (727 mg) vitamin E/d did not adversely affect healthy elderly persons. We have now assessed the effects of 4 mo of supplementation with 60, 200, or 800 IU (55, 182, or 727 mg) all-rac-alpha-tocopherol/d on general health, nutrient status, liver enzyme function, thyroid hormone concentrations, creatinine concentrations, serum autoantibodies, killing of Candida albicans by neutrophils, and bleeding time in 88 healthy subjects aged >65 y participating in a double-blind, placebo-controlled trial. No side effects were reported by the subjects. Vitamin E supplementation had no effect on body weight, plasma total proteins, albumin, glucose, plasma lipids or the lipoprotein profile, total bilirubin, alkaline phosphatase, serum aspartate aminotransferase, serum alanine aminotransferase, lactate dehydrogenase, serum urea nitrogen, total red blood cells, white blood cells or white blood cell differential counts, platelet number, bleeding time, hemoglobin, hematocrit, thyroid hormones, or urinary or serum creatinine concentrations. Values from all supplemented groups were within normal ranges for older adults and were not significantly different from values in the placebo group. Vitamin E supplementation had no significant effects on plasma concentrations of other antioxidant vitamins and minerals, glutathione peroxidase, superoxide dismutase, or total homocysteine. There was no significant effect of vitamin E on serum nonspecific immunoglobulin concentrations or anti-DNA and anti-thyroglobulin antibodies. The cytotoxic ability of neutrophils against Candida albicans was not compromised. Thus, 4 mo of supplementation with 60-800 IU vitamin E/d had no adverse effects. These results are relevant for determining risk-to-benefit ratios for vitamin E supplementation.

Vitamin E supplementation enhances cell-mediated immunity in healthy elderly subjects.

The effect of vitamin E supplementation on the immune response of healthy older adults was studied in a double-blind, placebo-controlled trial. Subjects (n = 32) resided in a metabolic research unit and received placebo or vitamin E (800 mg dl-alpha-tocopheryl acetate) for 30 d. Alpha-tocopherol content of plasma and peripheral blood mononuclear cells (PBMCs), delayed-type hypersensitivity skin test (DTH), mitogen-stimulated lymphocyte proliferation, as well as interleukin (IL)-1, IL-2, prostaglandin (PG) E2, and serum lipid peroxides were evaluated before and after treatment. In the vitamin E-supplemented group 1) alpha-tocopherol content was significantly higher (p less than 0.0001) in plasma and PBMCs, 2) cumulative diameter and number of positive antigen responses in DTH response were elevated (p less than 0.05), 3) IL-2 production and mitogenic response to optimal doses of concanavalin A were increased (p less than 0.05), and 4) PGE2 synthesis by PBMCs (p less than 0.005) and plasma lipid peroxides (p less than 0.001) were reduced. Short-term vitamin E supplementation improves immune responsiveness in healthy elderly individuals; this effect appears to be mediated by a decrease in PGE2 and/or other lipid-peroxidation products.

Plasma antioxidant status after high-dose chemotherapy: a randomized trial of parenteral nutrition in bone marrow transplantation patients.

BACKGROUND: Chemotherapy and radiation therapy result in increased free radical formation and depletion of tissue antioxidants. It is not known whether parenteral nutrition (PN) administered during bone marrow transplantation (BMT) supports systemic antioxidant status. OBJECTIVE: The aims of the study were to determine 1) whether high-dose chemotherapy decreases concentrations of major circulating antioxidants in patients undergoing BMT and 2) whether administration of standard PN maintains systemic antioxidant concentrations compared with PN containing micronutrients and minimal lipids alone. DESIGN: Twenty-four BMT patients were randomly assigned to receive either standard PN containing conventional amounts of dextrose, amino acids, micronutrients, and lipid (120 kJ/d) or a solution containing only micronutrients (identical to those in standard PN) and a small amount of lipid (12 kJ/d). Plasma antioxidant status was measured before conditioning therapy and serially at days 1, 3, 7, 10, and 14 after BMT. RESULTS: Plasma glutathione (GSH) and alpha- and gamma-tocopherol concentrations decreased and the GSH redox state became more oxidized after conditioning chemotherapy. Plasma cysteine concentrations were unchanged, whereas cystine concentrations increased. Plasma vitamin C and zinc concentrations and GSH peroxidase activity increased over time. Plasma alpha-tocopherol concentrations were lower in patients given standard PN. There were no differences in other plasma antioxidants between groups. CONCLUSIONS: A significant decline in GSH-glutathione disulfide, cysteine-cystine, and vitamin E status occurs after chemotherapy and BMT. Standard PN does not improve antioxidant status compared with administration of micronutrients alone. Further evaluation of PN formulations to support patients undergoing high-dose chemotherapy and BMT are needed.