Promoting physical activity and improving dietary quality of Singaporean adolescents: effectiveness of a school-based fitness and wellness program.

Limited data are available on the effectiveness of the school-based structured fitness and wellness program to influence dietary quality and physical activity levels in Singaporean adolescents. The study examined if a 20-h (over 10 weeks) school-based structured fitness and wellness module affects the diet quality indices, energy intakes, physical activity levels and the associated energy expenditures in a group of healthy, male adolescents with low diet quality and physical activity levels. Participant demography, anthropometry, dietary intake and daily physical activity were obtained at the beginning, mid-point and end of the 10-week program. Physical activity levels were assessed accelerometrically over a 1-weekday period. Dietary intake were taken using a structured 7-day food diary, and diet quality assessed using the Diet Quality Index-International (DQI-I). The 31 enrolled participants (age 19.8 ± 0.6 years) with body mass index (BMI) (19.8 ± 0.6 kg/m2) followed diets of low diet quality scores (48.3 ± 9.6 out of 100) and engaged in 3.87 ± 2.00 h of physical activity daily before the start of the intervention. Their dietary quality and physical activity levels did not change significantly throughout the intervention period. They scored poorly in the moderation and overall balance components of the diet quality assessment. The physical activity duration correlated inversely to the diet quality scores. Our results suggest that the prescribed school-based fitness and wellness module was ineffective in influencing the diet quality and physical activity levels of Singaporean male adolescents with low diet quality and physical activity levels.

Occurrence of azo food dyes and their effects on cellular inflammatory responses.

OBJECTIVES: The aim of this study was to examine the occurrence of five azo food dyes-tartrazine, sunset yellow, carmoisine, allura red, and ponceau 4 R-in the food supply chain of Singapore and their effects on the in vitro synthesis of leukotriene B4 (LTB4) and F2-isoprostanes. METHODS: Trained personnel recorded the names of foods and beverages sold in a local supermarket that contained at least one of the five azo dyes. The occurrence of the azo dyes in the local food supply was computed. The synthesis of LTB4 and F2-isoprostanes from freshly isolated blood neutrophils were measured using gas chromatography-mass spectrometry. RESULTS: Of the 1681 processed food items, 194 (11.54%) contained at least one of the five azo dyes. Tartrazine was most prevalent in food and beverage products sold in Singapore, followed by allura red, sunset yellow, ponceau 4 R, and carmoisine. The five azo dyes augmented the in vitro synthesis of LTB4 and F2-isoprostanes from blood neutrophils. Tartrazine was significantly more potent in increasing LTB4 synthesis than the other dyes, which exhibited similar potencies. The five food dyes increased the formation of F2-isoprostanes from blood neutrophils at all tested concentrations. CONCLUSION: The high prevalence of azo dyes in the food supply of Singapore and their ability to elicit proinflammatory responses in vitro suggest a potential health risk to the local population.

Common food antimicrobials: effects on cellular inflammation and oxidative damage and their estimated occurrence in Singapore.

BACKGROUND AND OBJECTIVES: The prevalence and potential health effects of common food antimicrobials in processed foods and beverages are relatively unknown in Singapore. The occurrence of chemical antimicrobials in processed foods and beverages and their effects on inflammation and oxidative stress in vitro were examined. METHODS AND STUDY DESIGN: The occurrence of antimicrobials in 1605 processed food and 359 beverage items were examined by surveying the ingredients on the product labels. Human neutrophils were exposed to physiologically relevant concentrations of common antimicrobials. Established markers of inflammation, l Leukotriene B4 and oxidative stress, F2-isoprostanes were measured using stable-isotope dilution gas chromatography-mass spectrometry. RESULTS: Antimicrobials were added to 23.2% of the processed foods and beverages. Sorbic, benzoic, lactic, propionic and acetic acids accounted for 84.8% of the added antimicrobials in the processed foods and beverages. 92.5% of the bread contained propionic acid. Lactic acid was the most common antimicrobial (44.4%) in cheeses. Sorbic acid was added to 63.2% of the margarines selected. Sauces (31.5%), energy drinks (50.0%), soft drinks (70.7%) and fruit cordials (66.6%) contained added benzoic acid. Benzoic and propionic acids at physiologically relevant concentrations augmented leukotriene B4formation (benzoicacid, EC50 = ~100 µg L-1and propionic acid, >200 µg L-1). Lactic and sorbic acids dose-dependently inhibited the F2-isoprostanes production (IC50 values ~100 µg L-1) and myeloperoxidase activity (IC50values ~100 µg L-1). CONCLUSIONS: Our results demonstrate that Singapore consumers are significantly exposed to food antimicrobials, and these molecules, in physiologically relevant concentrations, exert significant and differential effects in vitro.

Dietary Plant Sterols Supplementation Increases In Vivo Nitrite and Nitrate Production in Healthy Adults: A Randomized, Controlled Study.

A randomized, double-blinded, placebo-controlled and crossover study was conducted to simultaneously measure the effects, 3 h after consumption and after 4-wk daily exposure to plant sterols-enriched food product, on in vivo nitrite and nitrate production in healthy adults. Eighteen healthy participants (67% female, 35.3 [mean] ± 9.5 [SD] years, mean body mass index 22.8 kg/m2 ) received 2 soy milk (20 g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmityl esters (ß-sitosterol, 55%; campesterol, 29%; and stigmasterol, 23%). Nitrite and nitrate concentrations were measured in the blood plasma and urine, using stable isotope-labeled gas chromatography-mass spectrometry. L-arginine and asymmetric dimethylarginine concentrations in blood serum were measured using commercially available enzyme immunoassays. Nitrite and nitrate concentrations in blood plasma (nitrite 5.83 ± 0.50 vs. 4.52 ± 0.27; nitrate 15.78 ± 0.96 vs. 13.43 ± 0.81 µmol/L) and urine (nitrite 1.12 ± 0.22 vs. 0.92 ± 0.36, nitrate 12.23 ± 1.15 vs. 9.71 ± 2.04 µmol/L) were significantly elevated after 4-wk plant sterols supplementation Placebo and 3-h treatments did not affect the blood plasma and urinary concentrations of nitrite and nitrate. Circulating levels of L-arginine and asymmetric dimethylarginine were unchanged in the placebo and treatment arms. Total plant sterols, ß-Sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4-wk treatments compared to the placebo and 3-h treatments. Blood plasma nitrite and nitrate concentrations correlated significantly with the plasma total and specific plant sterol concentrations. Our results suggest that dietary plant sterols, in the combination used, can upregulate nitrite, and nitrate production in vivo.

Plant sterol-enriched soy milk consumption modulates 5-lipoxygenase, 12-lipoxygenase, and myeloperoxidase activities in healthy adults - a randomized-controlled trial.

A randomized, double blind, placebo-controlled and crossover study was conducted to simultaneously measure the effects, after 3-h and 4-week daily exposure to plant sterols-enriched food product, on inflammation, oxidative status, 5-lipoxygenase, 12-lipoxygenase, and myeloperoxidase activities in healthy adults. Eighteen healthy participants (67% female, 35.3 (mean) ± 9.5 (SD) years, mean body mass index 22.8 kg m-2) received two soy milk (20g) treatments daily: placebo and one containing 2.0 g free plant sterols equivalent of their palmitates (ß-sitosterol, 55%; campesterol, 29%; stigmasterol, 23%). F2-isoprostanes, leukotriene B4, sitosterol, campesterol, and stigmasterol concentrations were measured in the blood plasma and urine, using stable isotope-labeled gas chromatography-mass spectrometry. High-sensitivity c-reactive protein, tumor necrosis factor-α, and lipoxin A4 concentrations in blood serum were measured using commercially available enzyme immunoassays. Myeloperoxidase activity, serum lipid hydroperoxides, plasma and urinary F2-isoprostanes, plasma and urinary leukotriene B4, and plasma high-sensitivity c-reactive protein concentrations were significantly reduced, while circulating lipoxin A4 concentrations were significantly elevated after 4-week plant sterols treatment. Plant sterols treatment decreased plasma leukotriene B4 and increased plasma lipoxin A4 concentrations acutely. Total plant sterols, ß-sitosterol, campesterol, and stigmasterol concentrations were significantly elevated after 4-week treatments compared with the pre-treatment concentrations. Our results suggest that dietary plant sterols, in the combination used, can alleviate lipid peroxidation and inflammatory events in vivo. These effects are possibly exerted via the modulation of myeloperoxidase, 5-lipoxygenase, and 12-lipoxygenase activities.

Aged Garlic Supplement Protects Against Lipid Peroxidation in Hypercholesterolemic Individuals.

The health benefits of raw garlic intake has been extensively studied, but little is known about the biological effects of aged garlic consumption. A randomized, placebo-controlled, parallel-arm, double-blinded trial involving 41 hypercholesterolemic individuals was conducted to simultaneously examine and compare the blood lipid lowering and antioxidant effects after acute and extended exposures to aged and raw garlic supplements (1080 mg daily). Aged and raw garlic did not affect blood lipid concentrations in these hypercholesterolemic participants after acute and 13-week supplementation. The plasma and urinary F2-isoprostanes concentrations were significantly decreased after 13 weeks of aged garlic treatment. Aged garlic supplementation over 13 weeks also significantly decreased serum lipid hydroperoxide concentration and myeloperoxidase activity. Raw garlic treatments did not affect the F2-isoprostanes concentrations in blood plasma and urine, and lipid hydroperoxides in blood sera. Acute effects on the measured parameters were absent for both garlic treatments. In separate in vitro experiments, aqueous methanolic extract of aged garlic inhibited F2-isoprostanes formation and myeloperoxidase activity in freshly isolated human neutrophils to a greater extent than the raw garlic extract and S-allylcysteine at equivalent dosing concentrations. The aged garlic preparation was found to contain significantly higher total phenolic and S-allylcysteine contents than the raw garlic precursor. Our data showed that supplementation with aged garlic, not its raw garlic precursor, reduced oxidative stress and alleviated lipid peroxidation, possibly via the inhibition of myeloperoxidase. The differential antioxidant actions of the aged and raw garlic may be related to their different total phenolic contents and, to a lesser extent, their S-allylcysteine contents.

Relative Inhibitions of 5-Lipoxygenase and Myeloperoxidase and Free-Radical Scavenging Activities of Daidzein, Dihydrodaidzein, and Equol.

The effects of bioavailability and metabolic transformation on the biological activities of daidzein are relatively unknown. The effects of daidzein, dihydrodaidzein, and equol at physiologically relevant concentrations on the production of leukotriene B4 and F2-isoprostanes, and myeloperoxidase enzyme activity in freshly isolated human neutrophils were examined. Equol, at physiological concentrations, inhibited leukotriene B4 production (IC50-200 nmol/L) in human neutrophils significantly more than daidzein and dihydrodaidzein (IC50 values >1000 nmol/L). Daidzein, dihydrodaidzein, and equol did not affect the enzymatic hydrolysis of leukotriene A4 to leukotriene B4, suggesting that they exerted their inhibitory effects on the 5-lipoxygenase activity. Daidzein (IC50 = 600 nmol/L) protected against free radical peroxidation of arachidonic acid significantly more than did equol and dihydrodaidzein (IC50 values >1000 nmol/L). Equol also showed significantly greater inhibition of myeloperoxidase activity (IC50 = 450 nmol/L) when compared to daidzein and dihydrodaidzein. Equol accumulated within the human neutrophils at significantly higher concentrations than daidzein and dihydrodaidzein after incubation with the three compounds at physiologically relevant concentrations. Neutrophils were able to accumulate intracellular daidzein, dihydrodaidzein, and equol up to a concentration of ∼600 nmol/L. Our results provide in vitro evidence that the biological activities of daidzein are profoundly influenced by bioavailability and metabolic transformation.

Does influenza A infection increase oxidative damage?

Considerable data implicate oxidative damage in influenza pathogenesis. We examined temporal changes in oxidative damage using accurate biomarkers in an adult cohort with acute influenza infection and their relationships with clinical parameters. Clinical information and blood samples were collected during their acute illness and 3 months later. A fatigue questionnaire was administered 3 months following influenza infection. Thirty-five patients (mean age, 34 years) with polymerase chain reaction-confirmed influenza A infection were included; all patients returned for follow-up assessments. Adjusted levels of plasma F2-isoprostanes, total hydroxyeicosatetraenoic products (HETEs), 7ß-hydroxycholesterol and 7-ketocholesterol, serum gamma-glutamyltransferase, and high-sensitivity C-reactive protein (hsCRP) were increased during the acute illness compared with age-matched controls. Despite clinical recovery, levels of these biomarkers remained higher at month 3 compared with controls. A proportion of patients had persistent symptoms such as fatigue (23%), myalgia (14%), and arthralgia (11%) at month 3. Patients with significant fatigue had higher baseline levels of plasma F2-isoprostanes, F4-neuroprostanes, and total HETEs compared to those without fatigue. By contrast, patients with persistent arthralgia and myalgia had higher baseline levels of serum hsCRP compared to those without these symptoms. Our observations lead to the hypothesis that oxidative damage participates in the pathogenesis of influenza infection and postinfectious fatigue.

Cyclooxygenase-1 mediated platelet reactivity in young male smokers.

BACKGROUND: The purpose of this study is to investigate the acute and chronic effects of cigarette smoking on cyclooxygenase- 1(COX-1)-mediated platelet reactivity among cigarette smokers. METHODS: The levels of collagen-induced platelet aggregation, platelet COX-1 activity, and expressions were compared between smokers and age-matched nonsmokers. In smokers, the acute effects of cigarette smoking were assessed by repeating these measurements an hour after smoking. RESULTS: Twenty-five smokers and age-matched nonsmokers (all men; mean age, 29 years) were studied. Collagen-induced platelet aggregation and plasma/urinary thromboxane B2 (TXB2) and 11-dehydroxythromboxane B2 levels were higher in cigarette smokers compared to nonsmokers. Greater expression of platelet COX-1 was observed in smokers than in nonsmokers. Among smokers, collagen-induced platelet aggregation correlated positively with platelet volume and circulating nicotine and cotinine concentrations. The levels of plasma/urinary TXB2 were significantly increased an hour after cigarette smoking. CONCLUSION: Cigarette smoking aggravates COX-1-mediated platelet reactivity in young, otherwise healthy, smoking men.

Augmentation of 5-lipoxygenase activity and expression during dengue serotype-2 infection.

BACKGROUND: Leukotriene B4, a 5-lipoxygenase product of arachidonic acid with potent chemotactic effects on neutrophils, has not been assessed in dengue patients. In this study, plasma leukotriene B4 and serum high-sensitivity C-reactive protein levels were determined in adult patients during the febrile, convalescent and defervescent stages of dengue serotype-2 (DENV-2) infection, and compared with those of age-matched healthy and non-dengue febrile subjects. In vitro studies were performed to examine the effects of live and heat-inactivated DENV-2 on the activities and expression of 5-lipoxygenase in human neutrophils. RESULTS: Plasma leukotriene B4 was elevated during the febrile stages of dengue infection compared to levels during convalescence and in study controls. Plasma leukotriene B4 also correlated with serum high-sensitivity C-reactive protein in dengue patients (febrile, r = 0.91, p < 0.001; defervescence, r = 0.87, p < 0.001; convalescence, r = 0.87, p < 0.001). Exposure of human neutrophils to DENV-2 resulted in a significant rise in leukotriene B4; the extent of increase, however, did not differ between exposure to live and heat-inactivated DENV-2. Pre-incubation of either live or heat-inactivated DENV-2 resulted in reduced leukotriene B4 release by neutrophils, indicating that contact with dengue antigens (and not replication) triggers the neutrophil response. Production of leukotriene B4 was associated with an increase in 5-lipoxygenase expression in human neutrophils; addition of MK886 (a 5-lipoxygenase activating protein inhibitor) attenuated further increase in leukotriene B4 production. CONCLUSION: These findings provide important clinical and mechanistic data on the involvement of 5-lipoxygenase and its metabolites in dengue infection. Further studies are needed to elucidate the therapeutic implications of these findings.