Melanie D. Austin

Quercetin's Influence On Exercise Performance And Muscle Mitochondrial Biogenesis

PURPOSE To determine the influence of 2 wk of quercetin (Q; 1000 mg x d(-1)) compared with placebo (P) supplementation on exercise performance and skeletal muscle mitochondrial biogenesis in untrained, young adult males (N = 26, age = 20.2 +/- 0.4 yr, VO2max = 46.3 +/- 1.2 mL x kg(-1) x min(-1)). METHODS Using a randomized, crossover design with a 2-wk washout period, subjects provided blood and muscle biopsy samples presupplementation and postsupplementation periods and were given 12-min time trials on 15% graded treadmills after 60 min of moderate exercise preloads at 60% VO2max. RESULTS Plasma Q levels rose significantly in Q versus P during the 2-wk supplementation period (interaction P value <0.001). During the 12-min trial, the net change in distance achieved was significantly greater during Q (2.9%) compared with P (-1.2%; 29.5 +/- 11.5 vs -11.9 +/- 16.0 m, respectively, P = 0.038). Skeletal muscle messenger RNA expression tended to increase (range = 16-25%) during Q versus P for sirtuin 1 (interaction effect, P = 0.152), peroxisome proliferator-activated receptor gamma coactivator-1alpha (P = 0.192), cytochrome c oxidase (P = 0.081), and citrate synthase (P = 0.166). Muscle mitochondrial DNA (relative copy number per diploid nuclear genome) increased 140 +/- 154 (4.1%) with Q compared with -225 +/- 157 (6.0% decrease) with P (P = 0.098). CONCLUSIONS In summary, 1000 mg x d(-1) Q versus P for 2 wk by untrained males was associated with a small but significant improvement in 12-min treadmill time trial performance and modest but insignificant increases in the relative copy number of mitochondrial DNA and messenger RNA levels of four genes related to mitochondrial biogenesis.

Validation of Cosmed’s FitMate™ in Measuring Oxygen Consumption and Estimating Resting Metabolic Rate

The purpose of this study was to assess the validity and reliability of the FitMate™ metabolic system (Cosmed, Rome, Italy) in measuring oxygen consumption and estimating resting metabolic rate (RMR). The FitMate™ is a new, small (20 × 24 cm) metabolic analyzer designed for measurement of oxygen consumption and energy expenditure during rest and exercise. Subjects included 60 healthy adults (N = 30 males, N = 30 females) ranging in age from 19 to 65 years (mean ± SD age, 36.9 ± 13.4 years) and body mass index (BMI) from 19.2 to 44.8 kg/m2 (27.7 ± 6.2 kg/m2). Subjects were given two 10 min RMR tests in one test session during which RMR was measured simultaneously with the Douglas bag and FitMate™ systems. No significant differences were found between Douglas bag and FitMate™ systems for oxygen consumption (242 ± 49 and 240 ± 49 ml/min, respectively, P = 0.066, r = 0.97, mean ± SD absolute difference 2.83 ± 11.68 ml/min) or RMR (1,662 ± 340 and 1,668 ± 344 kcal/day, P = 0.579, r = 0.97, mean ± SD absolute difference 5.81 ± 80.70 kcal/day). These data indicate that the FitMate™ is a reliable and valid system for measuring oxygen consumption and RMR in adults.

Upper respiratory tract infection is reduced in physically fit and active adults

Objective Limited data imply an inverse relationship between physical activity or fitness level and the rates of upper respiratory tract infection (URTI). The purpose of this study was to monitor URTI symptoms and severity in a heterogeneous group of community adults and contrast across tertiles of physical activity and fitness levels while adjusting for potential confounders. Design A group of 1002 adults (ages 18–85 years, 60% female, 40% male) were followed for 12 weeks during the winter and fall seasons while monitoring URTI symptoms and severity using the Wisconsin Upper Respiratory Symptom Survey. Subjects reported frequency of aerobic activity, and rated their physical fitness level using a 10-point Likert scale. A general linear model, with adjustment for seven confounders, was used to examine the effect of exercise frequency and fitness level on the number of days with URTI and severity of symptoms. Results The number of days with URTI during the 12-week period was significantly reduced, 43% in subjects reporting ≥5 days/week aerobic exercise compared to those who were largely sedentary (≤1 day/week) and 46% when comparing subjects in the high versus low fitness tertile. URTI severity and symptomatology were also reduced 32% to 41% between high and low aerobic activity and physical fitness tertiles. Conclusions Perceived physical fitness and frequency of aerobic exercise are important correlates of reduced days with URTI and severity of symptoms during the winter and fall common cold seasons.

Influence of carbohydrate on cytokine and phagocytic responses to 2 h of rowing

PURPOSE This study examined the influence of carbohydrate (C) versus placebo (P) beverage ingestion on the phagocytic and cytokine responses to normal rowing training by 15 elite female rowers. METHODS Athletes received C or P before, during and after, two, 2-h bouts of rowing performed on consecutive days. Blood was collected before and 5-10 min and 1.5 h after rowing. Metabolic measures indicated that training was performed at moderate intensities, with some high-intensity intervals interspersed throughout the sessions. RESULTS Concentrations of blood neutrophils and monocytes, phagocytic activity, and plasma IL-1ra were significantly lower postexercise after C versus P ingestion. No differences were observed for oxidative burst activity, IL-6, IL-8, or TNFalpha. Glucose was significantly higher after 2 h of rowing with C ingestion; however, cortisol, growth hormone, epinephrine, norepinephrine, and CRP were not affected by carbohydrate. CONCLUSIONS These data indicate that carbohydrate compared with placebo ingestion attenuated the moderate rise in blood neutrophils, monocytes, phagocytosis, and plasma IL-1ra concentrations that followed 2-h bouts of training in elite female rowers. No changes in blood hormone concentrations were found.

Chia seed does not promote weight loss or alter disease risk factors in overweight adults

The objective of this study was to assess the effectiveness of chia seed (Salvia hispanica L) in promoting weight loss and altering disease risk factors in overweight adults. The hypothesis was that the high dietary fiber and alpha-linolenic (ALA) contents of chia seed would induce a small but significant decrease in body weight and fat and improve disease risk factors. Subjects were randomized to chia seed (CS) and placebo (P) groups, and under single-blinded procedures, ingested 25 g CS or P supplements mixed in 0.25 L water twice daily before the first and last meal for 12 weeks. Ninety nondiseased, overweight/obese men and women between the ages of 20 and 70 years were recruited into the study, with 76 subjects (n = 39 CS, n = 37 P) completing all phases of the study. Pre- and poststudy measures included body mass and composition (dual energy x-ray absorptiometry), inflammation markers from fasting blood samples (C-reactive protein, interleukin 6, monocyte chemoattractant protein 1, and tumor necrosis factor alpha), oxidative stress markers (trolox equivalent antioxidant capacity and plasma nitrite), blood pressure, and a serum lipid profile. Plasma ALA increased 24.4% compared to a 2.8% decrease in CS and P, respectively (interaction effect, P = .012). No group differences were measured for changes in plasma eicosapentaenoic acid and docosahexaenoic acid (interaction effects, P = .420 and .980, respectively). Pre-to-post measures of body composition, inflammation, oxidative stress, blood pressure, and lipoproteins did not differ between CS and P for both sexes. In conclusion, ingestion of 50 g/d CS vs P for 12 weeks by overweight/obese men and women had no influence on body mass or composition, or various disease risk factor measures.

Validation of Cosmed's FitMate™ in Measuring Exercise Metabolism∗

The purpose of this study was to assess the validity of the FitMate™ metabolic system (Cosmed, Rome, Italy) in measuring oxygen consumption during graded exercise. The FitMate™ is a new, small (20 × 24 cm) metabolic analyzer designed for measurement of oxygen consumption during rest and exercise. Subjects included 40 healthy adults (N = 20 males, N = 20 females) ranging in age from 18 to 37 kg/m2 (mean ± SD age, 22.5 ± 3.6 years) and body mass index (BMI) from 18.3 to 32.5 kg/m2 (23.2 ± 3.3 years). One-minute FitMate™ and Douglas bag measurements were made during steady state conditions at the end of each 3-minute stage of the Bruce treadmill graded exercise test, and subjects continued until they could not attain steady state exercise during a stage. Oxygen consumption difference scores (Douglas bag minus FitMate™ measurements) did not differ between males and females, so data were combined and analyzed for the entire group. During the first three stages, mean oxygen consumption did not differ significantly between the Douglas bag and FitMate™ systems (26.5 ± 1.1 and 26.7 ± 1.3 ml·kg−1·min−1, respectively, P = 0.140) with a mean absolute difference of 0.23 ± 0.91 ml·kg−1·min−1 or 14.2 ± 67.5 ml·min−1. In conclusion, the FitMate™ metabolic system accurately measures oxygen consumption during graded treadmill exercise when compared with the Douglas bag system in male and female adults.

Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial

Abstract Quercetin in culture with target cells and pathogens exerts anti-pathogenic activities against a wide variety of viruses and bacteria. A few small-scale human quercetin supplementation studies have produced conflicting results regarding quercetins effects on upper respiratory tract infection rates, and little is known regarding the appropriate human dose. The purpose of this randomized, double-blinded, placebo-controlled trial was to measure the influence of two quercetin doses (500 and 1000mg/day) compared to placebo on upper respiratory tract infection (URTI) rates in a large community group (N =1002) of subjects varying widely in age (18–85 years). Subjects ingested supplements for 12 weeks and logged URTI symptoms on a daily basis using the Wisconsin Upper Respiratory Symptom Survey (WURSS). No significant group differences were measured for URTI outcomes for all subjects combined, or when analyzing separately by gender, body mass index, and age categories. Regression analysis revealed that the strongest interaction effect with group status was self-reported fitness level. A separate analysis of subjects 40 years of age and older rating themselves in the top half of the entire group for fitness level (N =325) showed lower URTI severity (36% reduction, P =0.020) and URTI total sick days (31% reduction, P =0.048) for the Q-1000 group compared to placebo. In summary, for all subjects combined, quercetin supplementation over 12 weeks had no significant influence on URTI rates or symptomatology compared to placebo. A reduction in URTI total sick days and severity was noted in middle aged and older subjects ingesting 1000mgquercetin/day for 12 weeks who rated themselves as physically fit.

A 12-week supplementation with quercetin does not affect natural killer cell activity, granulocyte oxidative burst activity or granulocyte phagocytosis in female human subjects

Quercetin, a flavonoid found in fruits and vegetables, is a strong antioxidant with anti-inflammatory, antimicrobial and immune-modulating properties. The purpose of the present study was to investigate the effects of long-term quercetin supplementation on innate immune function and inflammation in human subjects. Female subjects (n 120; aged 30-79 years) were recruited from the community and randomised to one of three groups, with supplements administered using double-blinded procedures: 500 mg quercetin/d (n 38), 1000 mg quercetin/d (n 40) or placebo (n 42). Subjects ingested two soft chew supplements twice daily during the 12-week study period. Fasting blood samples were obtained pre- and post-study and were analysed for plasma quercetin, IL-6, TNF-alpha and leucocyte subset cell counts. Natural killer cell activity (NKCA) and lymphocyte subsets were assessed in a subset of seventy-four subjects. Granulocyte oxidative burst activity (GOBA) and phagocytosis were assessed in sixty-four subjects. Eighteen subjects had overlapping data. Quercetin supplementation at two doses compared with placebo increased plasma quercetin (interaction effect; P < 0.001) but had no significant influence on blood leucocyte subsets, plasma IL-6 or TNF-alpha concentration, NKCA, GOBA or phagocytosis. NKCA was inversely correlated with BMI (r - 0.25; P = 0.035) and body fat percentage (r - 0.38; P = 0.001), and positively correlated with self-reported physical fitness level (r 0.24; P = 0.032). In summary, results from the present double-blinded, placebo-controlled, randomised trial indicated that quercetin supplementation at 500 and 1000 mg/d for 12 weeks significantly increased plasma quercetin levels but had no influence on measures of innate immune function or inflammation in community-dwelling adult females.

The variable plasma quercetin response to 12-week quercetin supplementation in humans

Background/Objectives:Quercetin supplementation results in a variable plasma quercetin response in humans. The purpose of this study was to determine whether this variance is related to gender, age, body mass index (BMI), and other demographic and lifestyle factors.Subjects/Methods:Subjects (N=1002, ages 18–85 years, 60% female and 40% male) were recruited from the community and randomized to one of three groups, with supplements administered using double-blinded procedures: Q-500 (500 mg/day), Q-1000 (1000 mg/day), or placebo. Subjects ingested two soft chew supplements twice daily during the 12-week study. Fasting blood samples were obtained pre- and post-study, analyzed for plasma quercetin, and then compared between and within groups by gender, age group (<40, 40–59, and ⩾60 years), BMI (<25, 25–29.9, and ⩾30 kg/m2), self-reported physical fitness level, and diet intake (food group servings).Results:Quercetin supplementation over 12 weeks caused a significant increase in overnight-fasted plasma quercetin, with a net increase of 332±21.0 and 516±30.8 μg/l for Q-500 and Q-1000 compared with 53.6±6.4 μg/l for placebo (interaction effect, P<0.001). The increase in plasma quercetin was highly variable within each quercetin supplementation group, but was unrelated to age, gender, BMI, fitness levels, or diet intake.Conclusions:In summary, quercetin supplementation in doses of 500 and 1000 mg/day caused large but highly variable increases in plasma quercetin that were unrelated to demographic or lifestyle factors.

Influence of Quercetin Supplementation on Disease Risk Factors in Community-Dwelling Adults

BACKGROUND In vitro data indicate quercetin has antioxidative and anti-inflammatory functions with the potential to lower disease risk factors, but data in human beings are limited. OBJECTIVE The objective of this study was to investigate the effect of quercetin, vitamin C, and niacin supplements (500 mg quercetin, 125 mg vitamin C, and 5 mg niacin [Q-500]; 1,000 mg quercetin, 250 mg vitamin C, and 10 mg niacin [Q-1,000]), on disease risk factors in a large group of community adults (n=1,002, 60% women) varying widely in age and body mass index. DESIGN Subjects were randomized into one of three groups (placebo, Q-500, or Q-1,000) and ingested supplements for 12 weeks. Blood samples were taken pre- and postsupplementation, and plasma quercetin, inflammatory markers (ie, C-reactive protein and five cytokines), diagnostic blood chemistries, blood pressure, and blood lipid profiles were measured. RESULTS Plasma quercetin increased in the Q-500 and Q-1,000 groups. No differences in blood chemistries were found except for a small decrease in serum creatinine and increase in glomerular filtration rate in Q-500 and Q-1,000 groups. A small decrease in mean arterial blood pressure was measured for Q-500 and Q-1,000 groups compared to placebo. A difference in serum total cholesterol was measured between Q-500 and placebo groups, and there was small decrease in high-density lipoprotein cholesterol levels in the Q-1,000 group. Change in inflammatory measures did not differ between groups except for a slight decrease in interleukin-6 for the Q-1,000 group. CONCLUSIONS Q-500 or Q-1,000 supplementation for 12 weeks had a negligible influence on disease risk factors.