effects of dietary strawberry supplementation on ... · clinical study effects of dietary...

Effects of Dietary Strawberry Supplementation on AntioxidantBiomarkers in Obese Adults with Above Optimal Serum Lipids

Basu A Morris S Nguyen A Betts N M Fu D amp Lyons T J (2016) Effects of Dietary StrawberrySupplementation on Antioxidant Biomarkers in Obese Adults with Above Optimal Serum Lipids Journal ofnutrition and metabolism 2016 [3910630] httpsdoiorg10115520163910630

Published inJournal of nutrition and metabolism

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Download date26 Dec 2019

Clinical StudyEffects of Dietary Strawberry Supplementation on AntioxidantBiomarkers in Obese Adults with Above Optimal Serum Lipids

Arpita Basu1 Stacy Morris1 Angel Nguyen1 Nancy M Betts1

Dongxu Fu2 and Timothy J Lyons23

1Department of Nutritional Sciences College of Human Sciences Oklahoma State University Stillwater OK 74078 USA2Centre for Experimental Medicine Queenrsquos University of Belfast Belfast BT7 1NN UK3Section of Diabetes amp Endocrinology University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA

Correspondence should be addressed to Arpita Basu arpitabasuokstateedu

Received 2 March 2016 Accepted 19 May 2016

Academic Editor Stan Kubow

Copyright copy 2016 Arpita Basu et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Berries have shown several cardiovascular health benefits and have been associated with antioxidant functions in experimentalmodels Clinical studies are limited We examined the antioxidant effects of freeze-dried strawberries (FDS) in adults [119899 = 60 age49 plusmn 10 years BMI 36 plusmn 5 kgm2 (mean plusmn SD)] with abdominal adiposity and elevated serum lipids Participants were randomizedto one of the following arms low dose strawberry (25 gday FDS) low dose control beverage (LD-C) high dose strawberry (50 gdFDS) and high dose control beverage (HD-C) for 12 weeks Control beverages were matched for calories and total fiber Plasmaantioxidant capacity trace elements (copper iron selenium and zinc) whole blood glutathione (GSH) and enzyme activity(catalase glutathione peroxidase and glutathione reductase) were examined at screening (0 week) and after 12 weeksrsquo interventionAt 12 weeks plasma antioxidant capacity and glutathione levels were higher in the strawberry versus control groups (low and highdose FDS 45 and 42 for plasma antioxidant capacity and 28 and 36 for glutathione resp) glutathione was higher in thehigh versus low dose strawberry group (all 119901 lt 005) Serum catalase activity was higher in the low dose strawberry (43) versuscontrol group (119901 lt 001) No differences were noted in plasma trace elements and glutathione enzyme activity Dietary strawberriesmay selectively increase plasma antioxidant biomarkers in obese adults with elevated lipids

1 Introduction

Dietary berries a rich source of bioactive compounds espe-cially the polyphenols have been associated with protectiveeffects against chronic diseases especially lowering risk fac-tors of cardiovascular disease (CVD) [1ndash3] Oxidative stress isone of themajor contributors to the pathophysiology of CVDand is triggered by many factors such as obesity elevatedserum lipids and low dietary and cellular antioxidant status[4 5] The antioxidant system is a complex network ofvarious biomolecules that individually and synergisticallycounteract free radicals and protect against oxidative damageThe antioxidant enzymes such as catalase and the superoxidedismutase (SOD) serve as first line defenses against hydrogenperoxide and superoxide anions respectively while the glu-tathione enzyme system counteracts the peroxide moleculesgenerated as by-products of dismutase activity and from the

oxidation of biomolecules that results in lipid peroxides [4]In addition to these antioxidant enzymes dietary micronu-trients such as vitamins C and E and trace elements suchas copper iron selenium and zinc also play an importantrole in antioxidant and pro-oxidant activities [6] Manypolyphenol-containing foods and beverages such as berriescocoa and green tea as well as their extracts have beenreported to enhance the activities of antioxidant enzymes andto chelate metal ions thereby improving oxidative stress [7ndash9] However few clinical studies have examined their effectsin adults with cardiovascular risk factors such as those withobesity dyslipidemia and the metabolic syndrome

Among the popular sources of dietary berries straw-berries have been shown to alleviate CVD risk factors inclinical studies as well as in animal models of atheroscle-rosis [10] However only a few studies have reported theireffects on antioxidant biomarkers especially on antioxidant

Hindawi Publishing CorporationJournal of Nutrition and MetabolismVolume 2016 Article ID 3910630 9 pageshttpdxdoiorg10115520163910630

2 Journal of Nutrition and Metabolism

enzyme functions such as catalase and the glutathioneenzyme system Using an animal model of oxidative stresspretreatment with strawberries was shown to attenuate theethanol-induced decreases in catalase and SOD activities inthe gastric mucosa of rats [11] Similar findings have beenreported from other studies using green tea and fruit extracts[12 13] Clinical trials mostly in studies of short durationin healthy volunteers have shown the effects of differentforms of dietary berries in increasing plasma antioxidantcapacity and thiol groups but no effects on glutathioneenzymes [14] In a previously reported eight-week studyof green tea supplementation in adults with the metabolicsyndrome we reported a significant increase in whole bloodglutathione and a decrease in plasma iron as a result ofgreen tea intervention [15] Emerging research supports therole of berries such as raspberries and raspberry seed oiland native fruit extracts such as the Grewia asiatica fruit inincreasing the intracellular concentrations of glutathione andin modulating antioxidant enzyme activities in experimentalmodels of oxidative stress and dyslipidemia [16ndash18] Whilethese study findings are interesting the practical relevance islimited based on the dosing as well as the use of test agentsthat are part of complementary or folk medicine and notcommonly consumed in the daily human diet

Thus there is a need to investigate the effects of berrieson antioxidant biomarkers in clinical studies using achievabledietary doses In a dose-response study our group previouslyreported the effects of dietary freeze-dried strawberries inlowering total and LDL-cholesterol and lipid peroxidationin adults with abdominal obesity and elevated serum lipids[19] Using stored samples from our previous study [19]we measured selected biomarkers of antioxidant status fol-lowing low and high dose strawberry intervention In thecurrent report we hypothesize that dietary strawberries willimprove selected biomarkers of plasma antioxidant statusthus potentially benefitting cardiovascular health in adultsfollowing a 12-week supplementation of two doses of freeze-dried strawberry beverages compared to the calorie and fiber-matched controls Thus our specific study objectives wereto examine the effects of strawberries on circulating antiox-idant biomarkers using stored samples specifically plasmaantioxidant capacity plasma catalase glutathione peroxidaseand glutathione reductase enzyme activities whole bloodglutathione concentrations and plasma trace elements inobese adults with above normal serum lipids

2 Methods

The study design has been previously published [19] Brieflythis was a randomized controlled trial involving low and highdoses of freeze-dried strawberries and corresponding calorie-and fiber-matched controls The study was approved by theInstitutional Review Board at the University of OklahomaHealth Sciences Center and at Oklahoma State UniversityAll participants provided written informed consentThe trialis registered with ClinicalTrialsgov supported by the USNational Library of Medicine at the National Institutes ofHealth (httpsclinicaltrialsgovshowNCT01883401)

Table 1 Composition of strawberry and control beverages

Composition LD-FDS LD-C HD-FDS HD-CFDS g 25 mdash 50 mdashFiber g 40 40 80 80Calories kcal 75 80 150 144Protein g 18 mdash 35 mdashFat g 03 mdash 05 mdashCarbohydrates g 16 20 32 36Ash g 15 mdash 32 mdashVitamin C mg 55 mdash 109 mdashTotal phenolics1 mg 1001 mdash 2005 mdashTotal anthocyanins2 mg 78 mdash 155 mdashEllagic acid mg 106 mdash 220 mdashPhytosterols mg 23 mdash 50 mdashC control FDS freeze-dried strawberries HD high dose LD low dose1Expressed as mg gallic acid equivalents2Expressed as mg cyanidin-3-glucoside equivalents

21 Participants Inclusion and exclusion criteria have beendescribed previously [19] Men and women [aged 49 plusmn 10 y(meansplusmn SDs)] with abdominal adiposity and elevated serumlipids andwhowere free of any chronic diseases were enrolledin this randomized controlled study Recruitment and studyprocedures were conducted at the Clinical Research Center attheUniversity ofOklahomaHealth SciencesCenter and at theNutritional Sciences Clinical Assessment Unit at OklahomaState University Participants were recruited using flyers andcampus e-mail advertisements at both sites Each potentialrecruit received an initial telephone screening before thescreening visit

22 Interventions Table 1 describes the composition of thefreeze-dried strawberry beverages and the fiber and calorie-matched control beverages used in the study The freeze-dried strawberries were kindly donated by the CaliforniaStrawberry Commission (CSC) and the mixture of straw-berries used to generate the powder contained the Universityof California public cultivars as follows Camarosa (37)Ventana (13) Diamante (13) and 2 proprietary varieties(37) in production in 2010 Participants were randomlyassigned to consume one of the following four beveragesfor 12 wk (1) low dose FDS [LD-FDS 25 g reconstituted in2 cups (474mL) of water] (2) low dose calorie- and fiber-matched control [LD-C 4 g of fiber and 5 teaspoons (20 g)of cane sugar blended in 2 cups (474mL) of water] (3) highdose FDS [HD-FDS 50 g reconstituted in 2 cups (474mL) ofwater] or (4) high dose calorie- and fiber-matched control[HD-C 8 g of fiber and 9 teaspoons (36 g) of cane sugarblended in 2 cups (474mL) ofwater]Thefiber used in controlbeverages was composed of vegetable fibers and naturalgums and contained both insoluble and soluble fiber (1 2)per serving (Fiberstir) In addition the control beveragescontained added red food color (McCormick amp CompanyBaltimore MD) and artificial strawberry-flavored Kool-Aid(Kraft Foods Pittsburgh PA) to mimic the color and flavor ofthe FDS beverages Participants were asked to consume one

Journal of Nutrition and Metabolism 3

cup in the morning and the second in the evening at least 6ndash8 h apart Participants were instructed to add the strawberryor control beverages as a snack to their usual diet and notto use it to replace any meals Since the strawberry powder issticky in consistency especially when reconstituted in waterthe participants were provided specific instructions on thepreparation and storage of the test drinks and demonstrationon how to rinse the cups to ensure no wastage of the testpowder Compliancewas assessed by the return of unused testpowder and mandatory three days per week visit to the clinicfor monitored consumption of the beverages In additionplasma ellagic acidwas alsomeasured as described previously[19]

23 Anthropometrics and Clinical and Dietary AnalysesBody weight was recorded on an uncarpeted surface withthe SECA 644 Multifunctional Hand Rail Scale (SECA)and recorded to the nearest 01 kg Height was measuredwithout shoes using the Accustat Genentech Stadiometerand recorded to the nearest 01 cm Waist circumference wasmeasured at the superior iliac crest using the Gulick II TapeMeasure (Vital Signs) Fasting blood samples were collectedand serum was promptly transported to the Universityof Oklahoma Medical Center Laboratory for analyses ofglucose lipid profiles (total cholesterol TG LDL-cholesteroland HDL-cholesterol) and other blood variables includingsafety variables (hemoglobin platelets white blood cells liverenzymes creatinine and blood urea nitrogen) using auto-mated diagnostic equipment (Abbott Architect Instruments)following standard protocols at the University of OklahomaMedical Center Micronutrient intakes were estimated basedon three-day food records collected at screening and 12wkof the study Three-day averages (two weekdays and oneweekend day) of micronutrient and fruit and vegetableintakes were analyzed using Nutritionist Pro (version 322007 Axxya Systems)

24 Plasma Antioxidant Capacity and Whole Blood Glu-tathione Plasma antioxidant capacity was measured usingthe assay developed by Miller et al [20] The average intra-assay CV was 46 Reduced glutathione content in hep-arinizedwhole blood sample wasmeasured using themethoddescribed by Beutler et al [21] Briefly 100 120583L of hemolyzedblood sample and 200 120583L of 25mmolL 551015840-dithiobis-2-nitrobenzoic acid (Sigma St Louis Missouri) were mixedin tubes containing 19mL Tris-HCl buffer (pH 80) Theabsorbance of the yellow thiolate anion was measured at412 nm Reduced glutathione (Sigma) was used as a standardCalibration curve was used to calculate concentration andwas expressed as micrograms per gram hemoglobin Theaverage interassay CV was 52

25 Serum Catalase Glutathione Peroxidase and GlutathioneReductase Activity Serum catalase activity and glutathionereductase activity were measured using Catalase Assay Kitand the Glutathione Reductase Assay Kit (Cayman ChemicalCompany Ann Arbor Michigan USA) using the spec-trophotometric assays based on the manufacturerrsquos protocol

The average interassay CV was 46 and 52 respectivelyGlutathione peroxidase was measured by using GPx-340(OxisResearch) based on the manufacturerrsquos protocol Theaverage interassay CV was 66

26 Trace Element Analysis Plasma levels of copper ironselenium and zinc were measured using inductively coupledplasma quadrupole mass spectroscopy (Elan 9000 PerkinElmer Norwalk CT) as described [22] All plasma sampleswere diluted 20-fold (200120583L diluted to 4mL) with 01nitric oxide (GFS Chemicals Powell OH) in ultrapure waterStandard solutions of selected trace elements were preparedby dilution of certified standard solutions (Perkin ElmerNorwalk CT) The calibration standards were prepared in01 nitric acid solution at 0 50 and 100 120583gL All samplesand standards were spiked with 10120583gL gallium as an internalstandard (Perkin Elmer Norwalk CT) Polypropylene plas-ticware (Sarstedt Inc Newton NC) was used for reagent andsample preparation to avoid metal contamination Qualitycontrol samples (Utak Laboratories Inc Valencia CA) wereused to verify method performance and confirm obtainedvalues were within recommended ranges Quantitative anal-yses were performed using the scanning mode of dataacquisition For each element peak area (signal) was divided(normalized) by the signal from the internal standard Basedon triplicate analyses the estimated average interassay CV forcopper iron selenium and zinc was in the range of 2ndash7

27 Data Analysis For all measures descriptive statisticswere calculated and graphs drawn to identify outliers nodata points were determined to be outliers Target sample sizewas calculated to include 15 participants per group to detecta minimum difference of 12 in whole blood glutathionewith 80 power based on our previous study [15] Ourprimary groups of comparisons were as follows low doseFDS versus high dose FDS and low and high dose FDSversus calorie- and fiber-matched control groups For eachvariable mean differences between strawberry and controlgroups at baseline and at 12 weeks were assessed using themultivariate analysis of variance (MANOVA) followed byBonferroni post hoc analyses All statistical tests were 2-tailedwith significance level set at 005 SPSS forWindows (version150 SPSS 2006) was used for the statistical calculations

3 Results

The baseline characteristics of our study participants arepresented in Table 2 No significant differences in baselinecharacteristics were observed among the strawberry groupsand the corresponding control groups As shown in Figure 1a total of 85 participants were screened for the study and66 were enrolled upon satisfying the inclusion and exclu-sion criteria Among those enrolled six participants with-drew because of time constraints and thus 60 participantscompleted the 12-wk study in the strawberry and controlarms Among these participants compliance was 100 forthe strawberry groups and 97 for the control groups asassessed by mandatory weekly visits (3 dwk) and return of


Table 2 Baseline characteristics and dietary trace element intake of the study participants1

Variable LD-FDS LD-C HD-FDS HD-C(119899 = 15) (119899 = 15) (119899 = 15) (119899 = 15)

Age (years) 50 plusmn 10 48 plusmn 10 49 plusmn 11 48 plusmn 10MF (119899119899) 114 114 213 114Waist (cm) 104 plusmn 76 109 plusmn 81 114 plusmn 127 107 plusmn 66Height (cm) 165 plusmn 58 165 plusmn 67 164 plusmn 65 169 plusmn 76Weight (kg) 95 plusmn 14 100 plusmn 12 101 plusmn 18 99 plusmn 15BMI (kgm2) 345 plusmn 44 370 plusmn 44 380 plusmn 71 350 plusmn 52Fasting glucose (mmolL) 55 plusmn 014 57 plusmn 018 52 plusmn 019 53 plusmn 025Triglycerides (mmolL) 17 plusmn 023 14 plusmn 017 19 plusmn 020 20 plusmn 021Total cholesterol (mmolL) 52 plusmn 028 52 plusmn 013 55 plusmn 018 53 plusmn 023LDL-cholesterol (mmolL) 31 plusmn 023 31 plusmn 015 34 plusmn 018 32 plusmn 021HDL-cholesterol (mmolL) 12 plusmn 010 13 plusmn 008 13 plusmn 010 12 plusmn 008BUN (mgdL) 14 plusmn 23 16 plusmn 45 16 plusmn 42 17 plusmn 50Creatinine (mgdL) 08 plusmn 02 08 plusmn 02 08 plusmn 02 09 plusmn 03AST (UL) 29 plusmn 10 26 plusmn 7 25 plusmn 4 25 plusmn 7ALT (UL) 34 plusmn 12 34 plusmn 12 30 plusmn 11 31 plusmn 12WBC (119899 times 10minus3) 66 plusmn 12 67 plusmn 14 67 plusmn 17 71 plusmn 15RBC (119899 times 10minus6) 46 plusmn 05 45 plusmn 03 46 plusmn 06 48 plusmn 04Hb (gdL) 14 plusmn 14 14 plusmn 13 14 plusmn 14 14 plusmn 16Multivitamin users () 200 200 200 100Fruit servings (119899wk) 12 10 12 10Vegetable servings (119899wk) 10 11 11 121Values are mean plusmn SDAST aspartate aminotransferase ALT alanine aminotransferase BMI bodymass index BUN blood urea nitrogen C control FDS freeze-dried strawberriesHb hemoglobin HD high dose LD low dose RBC red blood cell WBC white blood cellNo significant differences were noted among any groups using the multivariate analysis of variance (MANOVA) at baseline for each variable

any unconsumed beverages on the days the participants didnot come to the clinic Ellagic acid was detectable in thestrawberry group at 12 weeks but not at baseline as well asin the control groups as reported previously [19] No adverseevents were reported in the study

31 Plasma Antioxidant Capacity and Enzyme ActivityPlasma antioxidant capacity and whole blood glutathionewere not statistically different at baseline but were signifi-cantly higher in the low and high dose strawberry groupscompared to their calorie- and fiber-matched controls (all119901 lt 001 Table 3) While plasma antioxidant capacity didnot differ between the low and high dose strawberry groupsblood glutathione was significantly higher in the high doseversus low dose strawberry group at 12 weeks of the study(119901 lt 005 Table 3) Serum catalase activity tended to belower in the high dose strawberry when compared to thecalorie- and fiber-matched controls (119901 = 006) while catalaseactivity was significantly higher in the low dose strawberryversus low dose calorie- and fiber-matched controls at 12weeks (119901 lt 001 Table 3) No differences were noted inglutathione peroxidase and glutathione reductase enzymeactivities among any groups at baseline or at 12 weeks of thestudy (Table 3)

32 Plasma Trace Elements and Micronutrient Intakes Wedid not observe any differences in plasma copper iron

selenium and zinc among any groups at baseline and at12 weeks of the study (Table 3) Dietary intakes of selectedmicronutrients including trace elements did not signifi-cantly vary among groups at any time point (Table 4)

4 Discussion

In this 12-week clinical study we examined the dose-responseeffects of dietary strawberries on selected biomarkers ofantioxidant status in obese adults with elevated serumlipids Overall our findings reveal strawberry interventionto increase plasma antioxidant capacity and whole bloodglutathione when compared to the matched controls thehigher dose was associated with a greater increase in glu-tathione when compared to the lower dose of strawberriesSerum catalase activity was increased only in the low dosestrawberry group compared to the controls while no effectsof either dose were noted on glutathione peroxidase andglutathione reductase enzyme activities Plasma copper ironselenium and zinc were also not affected by the strawberryintervention To our knowledge this is the first clinicalstudy to report the effects of two achievable dietary doses ofstrawberries on circulating antioxidant biomarkers in adultswith CVD risk factors These findings may further explainthe protective associations of berry fruit intake against CVDrisk factors especially obesity and diabetes as observed inprospective cohort studies [2 23]


Time constraints(iv) HD-C (n = 1)(iii) HD-FDS (n = 2)(ii) LD-C (n = 2)(i) LD-FDS (n = 1)

Excluded (n = 6)

15group)Analyzed (n = 60

Randomized (n = 66)

Not meeting criteriaExcluded (n = 19)

LD-C (n = 17) HD-C (n = 16)(n = 17)

HD-FDS (50gday)(n = 16)

LD-FDS (25 gday)

Eligibility confirmation enrollmentand randomization in the study (n = 66)

Phone screened (n = 85)

Figure 1 Flow of participants through the trial C control FDS freeze-dried strawberries HD high dose LD low dose

Plasma antioxidant capacity a biomarker of enzymaticas well as nonenzymatic antioxidants has been shown tobe increased by many studies using strawberries and otherberry polyphenols [1] In healthy volunteers strawberryintervention at doses comparable to those used in our studyshowed a significant increase in plasma antioxidant capacityindicating a direct absorption of strawberry antioxidants suchas polyphenols and vitamins andor an enhanced productionof endogenous antioxidants [24ndash26] Among the endogenousantioxidant defensemechanisms catalase and the glutathioneenzyme system play key roles in neutralizing oxidative dam-age induced by hydrogen peroxide and its subsequent abilityto generate the hydroxyl radical [4] Using animal modelsof oxidative stress berry polyphenols have been shownto upregulate the synthesis of intracellular glutathione andglutathione peroxidase activity and attenuate mitochondrialoxidative stress [27] These mechanistic findings have beensupported by a few clinical studies reporting the effects ofberries on antioxidant enzymes A six-week dietary inter-vention study in junior athletes who were administeredan acai berry-based juice blend showed a trend towardsincreased catalase and glutathione reductase activities but noeffects on glutathione peroxidase at one-hour after exercisephase However no effects were noted in enzyme activitiesin the resting state in these young athletes [28] Another

three-week intervention of an antioxidant rich berry juiceblend in hemodialysis patients revealed a significant increasein blood glutathione levels thus improving oxidative stressin people with chronic kidney disease [29] In a two-week intervention study in healthy volunteers a polyphenol-rich juice was also shown to upregulate leucocyte proteinexpression of the phase II anticarcinogenic and antioxidantenzyme glutathione-S-transferase [30] In our study weobserved a dose-dependent increase in blood glutathione inour participants with CVD risk factors and a higher activityof catalase enzyme only in the low dose strawberry groupInterestingly we also observed a trend towards decreasedcatalase activity following high dose strawberry interventionsimilar to a decrease in erythrocyte catalase activity observedafter an intervention with high polyphenol orange juice [31]These effects have been explained by the ability of polyphe-nols to ldquosparerdquo endogenous antioxidants andor regenerateother antioxidants to improve their synergistic action invivo [31] In general whole strawberries contain vitaminsand carotenoids as antioxidants in addition to polyphenols[32] and these may modulate endogenous enzyme activitiesdepending on the ldquobaseline antioxidant statusrdquo in our par-ticipants While we did not measure plasma vitamins in ourstudywe report lowdietary intakes of vitaminCandE aswellas of fruits and vegetables in our participants when compared


Table 3 Antioxidant enzyme activities and trace element status following a 12-week strawberry or placebo beverage supplementation


Plasma antioxidant capacity (120583molL)0wk 16 plusmn 02 17 plusmn 03 18 plusmn 03 15 plusmn 0312 wk 29 plusmn 03lowast 16 plusmn 03 31 plusmn 03lowast 12 plusmn 02

Serum catalase (UmL)0wk 38 plusmn 12 47 plusmn 11 52 plusmn 15 45 plusmn 2012wk 67 plusmn 23lowast 32 plusmn 9 40 plusmn 13 54 plusmn 18

Serum glutathione peroxidase (mUmL)0wk 139 plusmn 40 137 plusmn 38 147 plusmn 45 124 plusmn 2812 wk 132 plusmn 39 140 plusmn 47 146 plusmn 33 115 plusmn 20

Serum glutathione reductase (UL)0wk 357 plusmn 17 305 plusmn 12 361 plusmn 9 404 plusmn 1812 wk 451 plusmn 21 285 plusmn 17 326 plusmn 12 372 plusmn 21

Whole blood glutathione (120583ggHb)0wk 1657 plusmn 57 1898 plusmn 52 1824 plusmn 38 1789 plusmn 6312wk 2295 plusmn 158lowastpara 1775 plusmn 48 2860 plusmn 121lowast 1862 plusmn 62

Plasma iron (mgdL)0wk 09 plusmn 01 18 plusmn 06 10 plusmn 01 09 plusmn 0112 wk 12 plusmn 01 10 plusmn 01 11 plusmn 02 13 plusmn 03

Plasma copper (mgdL)0wk 13 plusmn 01 14 plusmn 02 18 plusmn 04 13 plusmn 0112 wk 15 plusmn 01 16 plusmn 01 14 plusmn 01 15 plusmn 01

Plasma selenium (mgdL)0wk 010 plusmn 002 014 plusmn 003 015 plusmn 002 013 plusmn 00212wk 009 plusmn 002 011 plusmn 003 014 plusmn 002 011 plusmn 003

Plasma zinc (mgdL)0wk 11 plusmn 02 13 plusmn 03 12 plusmn 01 10 plusmn 0212 wk 06 plusmn 01 09 plusmn 02 09 plusmn 02 10 plusmn 02

Values are mean plusmn SEC control FDS freeze-dried strawberries Hb hemoglobin HD high dose LD low dose RBC red blood cell WBC white blood cell119901 values are derived from the multivariate analysis of variance (MANOVA) assessing differences between strawberry and control groups at 0 and 12 wk of thestudy for each variablelowast119901 lt 001 versus respective controls para119901 lt 001 versus HD-FDS 119901 = 006 versus HD-C

to the dietary recommendations [33 34] Nevertheless inview of the fact that more than 80 of the US population donot meet the national recommendations of intakes for fruitsand vegetables [34] our study reveals supplementation of lowas well as high dose strawberries confer some antioxidantprotection in obese adults

Some trace elements such as copper and iron havebeen shown to increase oxidative stress while others suchas zinc and selenium are essential constituents of the antiox-idant enzymes especially superoxide dismutase and theglutathione enzyme system [4 6 35] Polyphenols have beenshown to chelatemetal ions including iron andhave beenpro-posed as treatment agents in iron overload conditions such asthalassemia [36] Grape seed polyphenol supplementation inhealthy piglets were shown to cause a slight decrease in liverconcentrations of copper and zinc though both elementswere within the normal physiological limits when compared

to control animals [37] Clinical studies are limited and showsomewhat conflicting results Cereal grain polyphenols havebeen shown to decrease postprandial zinc absorption inyoung adults [38] while a three-month supplementation ofgreen tea polyphenols was reported to increase serum zincand lower serum iron in obese adults [39]Wehave previouslyreported the effects of green tea polyphenols in loweringplasma iron in obese adults with the metabolic syndrome[15] In our current study dietary strawberries at low andhigh doses had no effects on plasma trace elements in obeseadults with elevated serum lipids Thus further studies areneeded on the role of polyphenols derived from differentdietary sources in modulating trace element status in adultswith CVD risk factors

Our study has some limitations including a small samplesize and the selection of otherwise healthy obese adults withabove optimal serum lipids and these may explain some


Table 4 Dietary micronutrient intake at baseline and 12 weeks of the study


Copper intake (mgd)0wk 07 plusmn 03 06 plusmn 03 07 plusmn 02 065 plusmn 0312 wk 08 plusmn 03 06 plusmn 03 06 plusmn 02 08 plusmn 03

Iron intake (mgd)0wk 10 plusmn 8 12 plusmn 10 15 plusmn 7 9 plusmn 712wk 12 plusmn 8 13 plusmn 9 13 plusmn 10 11 plusmn 9

Selenium intake (120583gd)0wk 37 plusmn 15 45 plusmn 22 30 plusmn 12 38 plusmn 1512 wk 41 plusmn 13 47 plusmn 20 35 plusmn 10 40 plusmn 10

Zinc intake (mgd)0wk 68 plusmn 43 73 plusmn 55 71 plusmn 33 85 plusmn 4012wk 72 plusmn 35 81 plusmn 45 78 plusmn 27 93 plusmn 35

Vitamin C intake (mgd)0wk 40 plusmn 50 39 plusmn 76 35 plusmn 37 35 plusmn 3812 wk 37 plusmn 89 34 plusmn 46 38 plusmn 55 31 plusmn 28

Vitamin E intake (mgd)0wk 13 plusmn 02 12 plusmn 02 12 plusmn 02 14 plusmn 0212 wk 15 plusmn 03 10 plusmn 01 17 plusmn 03 12 plusmn 01

Beta-carotene intake (mgd)0wk 25 plusmn 08 21 plusmn 05 18 plusmn 06 20 plusmn 0712 wk 18 plusmn 09 24 plusmn 08 21 plusmn 08 17 plusmn 05

Values are mean plusmn SEC control FDS freeze-dried strawberries HD high dose LD low doseNo significant differences were noted among any groups using the multivariate analysis of variance (MANOVA) at baseline and 12wk for each variable

of our null findings Also while we previously measuredlipid peroxidation which revealed a decrease with strawberrysupplementation [19] other biomarkers of oxidative stresssuch as protein carbonyls and biomarkers of DNA damagemust also be determined in future studies In addition we didnot measure other biomarkers of antioxidant status such ascirculating or tissue vitamin C which also play an importantrole in the cellular antioxidant defense mechanism Finallywe measured levels of these antioxidants in the fasting orldquoresting staterdquo following the strawberry intervention butas shown in previous studies stress-inducing conditionssuch as exercise or the postprandial phase may elicit amore pronounced difference in thesemeasures of antioxidantenzymes

5 Conclusions

Our study findings support the hypothesis that dietarystrawberries selectively increase antioxidant biomarkers inobese adults with elevated serum lipids especially plasmaantioxidant capacity glutathione and catalase enzyme activ-ity Obesity is an underlying risk factor for many chronicconditions including CVD and has been associated withincreased oxidative stress and antioxidant deficiencies Thusdietary strawberries in addition to providing a significantsource of antioxidant polyphenols and vitamin C can alsoincrease endogenous antioxidant capacity This may offer

additional protection against obesity-related conditions suchas CVD the metabolic syndrome and type 2 diabetes

Competing Interests

The authors have no conflict of interests

Authorsrsquo Contributions

Arpita Basu Nancy M Betts and Timothy J Lyons designedresearch analyzed data and wrote the paper Arpita BasuStacy Morris Angel Nguyen and Dongxu Fu conductedresearch and performed laboratory analyses Arpita Basu hadprimary responsibility for final content All authors read andapproved the final paper

Acknowledgments

This study was supported partly by a grant award fromThe California Strawberry Commission (Watsonville CA)to Arpita Basu Also support was received from the DeanrsquosResearch Incentive program in the College of Human Sci-ences at Oklahoma State University This publication wasmade possible byNIHGrant P20 RR 024215 from the Centersof Biomedical Research Excellence Program of the NationalCenter for Research Resources at University of OklahomaHealth Sciences Center (Timothy J Lyons)


References

[1] A Basu M Rhone and T J Lyons ldquoBerries emerging impacton cardiovascular healthrdquo Nutrition Reviews vol 68 no 3 pp168ndash177 2010

[2] N M Wedick A Pan A Cassidy et al ldquoDietary flavonoidintakes and risk of type 2 diabetes in US men and womenrdquoAmerican Journal of Clinical Nutrition vol 95 no 4 pp 925ndash933 2012

[3] A Cassidy E J OrsquoReilly C Kay et al ldquoHabitual intake offlavonoid subclasses and incident hypertension in adultsrdquoAmerican Journal of Clinical Nutrition vol 93 no 2 pp 338ndash347 2011

[4] M Valko D Leibfritz J Moncol M T D Cronin M Mazurand J Telser ldquoFree radicals and antioxidants in normal physi-ological functions and human diseaserdquo International Journal ofBiochemistry and Cell Biology vol 39 no 1 pp 44ndash84 2007

[5] J F Keaney Jr M G Larson R S Vasan et al ldquoObesity andsystemic oxidative stress clinical correlates of oxidative stressin the Framingham studyrdquo Arteriosclerosis Thrombosis andVascular Biology vol 23 no 3 pp 434ndash439 2003

[6] M Valko K Jomova C J Rhodes K Kuca and K MusılekldquoRedox- and non-redox-metal-induced formation of free radi-cals and their role in human diseaserdquoArchives of Toxicology vol90 no 1 pp 1ndash37 2016

[7] S Mandel O Weinreb L Reznichenko L Kalfon and TAmit ldquoGreen tea catechins as brain-permeable non toxic ironchelators to ldquoiron out ironrdquo from the brainrdquo Journal of NeuralTransmission Supplementa no 71 pp 249ndash257 2006

[8] D Rugina Z Diaconeasa C Coman A Bunea C Socaciu andA Pintea ldquoChokeberry anthocyanin extract as pancreatic120573-cellprotectors in twomodels of induced oxidative stressrdquoOxidativeMedicine and Cellular Longevity vol 2015 Article ID 429075 10pages 2015

[9] M A Martın E Fernandez-Millan S Ramos L Bravo andL Goya ldquoCocoa flavonoid epicatechin protects pancreatic betacell viability and function against oxidative stressrdquo MolecularNutrition and Food Research vol 58 no 3 pp 447ndash456 2014

[10] A Basu A Nguyen N M Betts and T J Lyons ldquoStrawberry asa functional food an evidence-based reviewrdquo Critical Reviewsin Food Science and Nutrition vol 54 no 6 pp 790ndash806 2014

[11] J M Alvarez-Suarez D Dekanski S Ristic et al ldquoStrawberrypolyphenols attenuate ethanol-induced gastric lesions in ratsby activation of antioxidant enzymes and attenuation of MDAincreaserdquo PLoS ONE vol 6 no 10 Article ID e25878 2011

[12] P V A Babu K E Sabitha and C S Shyamaladevi ldquoThera-peutic effect of green tea extract on oxidative stress in aortaand heart of streptozotocin diabetic ratsrdquo Chemico-BiologicalInteractions vol 162 no 2 pp 114ndash120 2006

[13] A K Kumar and K Vijayalakshmi ldquoProtective effect of punicagranatumpeel and vitis vinifera seeds on den-induced oxidativestress and hepatocellular damage in ratsrdquo Applied Biochemistryand Biotechnology vol 175 no 1 pp 410ndash420 2015

[14] C Del Bo D Martini M Porrini D Klimis-Zacas and P RisoldquoBerries and oxidative stress markers an overview of humanintervention studiesrdquo Food and Function vol 6 no 9 pp 2890ndash2917 2015

[15] A Basu N M Betts A Mulugeta C Tong E Newman andT J Lyons ldquoGreen tea supplementation increases glutathioneand plasma antioxidant capacity in adults with the metabolicsyndromerdquo Nutrition Research vol 33 no 3 pp 180ndash187 2013

[16] B Fotschki A Jurgonski J Juskiewicz and Z ZdunczykldquoDietary supplementation with raspberry seed oil modulatesliver functions inflammatory state and lipid metabolism inratsrdquo Journal of Nutrition vol 145 no 8 pp 1793ndash1799 2015

[17] H A H Khattab N A El-Shitany I Z A Abdallah F MYousef and H M Alkreathy ldquoAntihyperglycemic potential ofGrewia asiatica fruit extract against streptozotocin-inducedhyperglycemia in rats anti-inflammatory and antioxidantmechanismsrdquo Oxidative Medicine and Cellular Longevity vol2015 Article ID 549743 7 pages 2015

[18] F Jimenez-Aspee C Theoduloz F Avila et al ldquoThe Chileanwild raspberry (Rubus geoides Sm) increases intracellular GSHcontent and protects against H

2O2and methylglyoxal-induced

damage in AGS cellsrdquo Food Chemistry vol 194 pp 908ndash9192016

[19] A Basu N M Betts A Nguyen E D Newman D Fu andT J Lyons ldquoFreeze-dried strawberries lower serum cholesteroland lipid peroxidation in adults with abdominal adiposity andelevated serum lipidsrdquo Journal of Nutrition vol 144 no 6 pp830ndash837 2014

[20] N J Miller C Rice-Evans M J Davies V Gopinathan andA Milner ldquoA novel method for measuring antioxidant capacityand its application to monitoring the antioxidant status inpremature neonatesrdquoClinical Science vol 84 no 4 pp 407ndash4121993

[21] E Beutler O Duron and BM Kelly ldquoImprovedmethod for thedetermination of blood glutathionerdquoThe Journal of Laboratoryand Clinical Medicine vol 61 pp 882ndash888 1963

[22] L Hubbs-Tait A Mulugeta A Bogale T S Kennedy E RBaker and B J Stoecker ldquoMain and interaction effects of ironzinc lead and parenting on childrenrsquos cognitive outcomesrdquoDevelopmental Neuropsychology vol 34 no 2 pp 175ndash1952009

[23] M L Bertoia K J Mukamal L E Cahill et al ldquoChanges inintake of fruits and vegetables and weight change in UnitedStatesmen andwomen followed for up to 24 years analysis fromthree prospective cohort studiesrdquo PLoS Medicine vol 12 no 9Article ID e1001878 2015

[24] G Cao R M Russell N Lischner and R L Prior ldquoSerumantioxidant capacity is increased by consumption of strawber-ries spinach red wine or vitamin C in elderly womenrdquo Journalof Nutrition vol 128 no 12 pp 2383ndash2390 1998

[25] S M Henning N P Seeram Y Zhang et al ldquoStrawberryconsumption is associated with increased antioxidant capacityin serumrdquo Journal of Medicinal Food vol 13 no 1 pp 116ndash1222010

[26] J M Alvarez-Suarez F Giampieri S Tulipani et al ldquoOne-month strawberry-rich anthocyanin supplementation amelio-rates cardiovascular risk oxidative stress markers and plateletactivation in humansrdquo Journal of Nutritional Biochemistry vol25 no 3 pp 289ndash294 2014

[27] J O Moskaug H Carlsen M C Myhrstad and R BlomhoffldquoPolyphenols and glutathione synthesis regulationrdquoThe Ameri-can journal of clinical nutrition vol 81 supplement 1 pp 277Sndash283S 2005

[28] E Sadowska-Krępa B Kłapcinska T Podgorski B SzadeK Tyl and A Hadzik ldquoEffects of supplementation with acai(Euterpe oleracea Mart) berry-based juice blend on the bloodantioxidant defence capacity and lipid profile in junior hurdlersA pilot studyrdquo Biology of Sport vol 32 no 2 pp 161ndash168 2015

[29] TM Spormann FW Albert T Rath et al ldquoAnthocyaninpoly-phenolic-rich fruit juice reduces oxidative cell damage in an


intervention study with patients on hemodialysisrdquo CancerEpidemiology Biomarkers and Prevention vol 17 no 12 pp3372ndash3380 2008

[30] T Hofmann U Liegibel P Winterhalter A Bub G Rechkem-mer and B L Pool-Zobel ldquoIntervention with polyphenol-richfruit juices results in an elevation of glutathione S-transferaseP1 (hGSTP1) protein expression in human leucocytes of healthyvolunteersrdquoMolecular Nutrition and Food Research vol 50 no12 pp 1191ndash1200 2006

[31] O D Rangel-Huerta C M Aguilera M V Martin et alldquoNormal or high polyphenol concentration in orange juiceaffects antioxidant activity blood pressure and body weight inobese or overweight adultsrdquo The Journal of Nutrition vol 145no 8 pp 1808ndash1816 2015

[32] US Department of Agriculture Agricultural Research Ser-vice and Nutrient Data Laboratory USDA National Nutri-ent Database for Standard Reference Release 28 VersionCurrent September 2015 Internet httpwwwarsusdagovbabhnrcndl

[33] Dietary Reference Intakes for Vitamin C Vitamin E Seleniumand Carotenoids National Academy of Sciences WashingtonDC USA 2000

[34] L V Moore K W Dodd F E Thompson K A Grimm S AKim and K S Scanlon ldquoUsing behavioral risk factor surveil-lance system data to estimate the percentage of the populationmeeting US department of agriculture food patterns fruitand vegetable intake recommendationsrdquo American Journal ofEpidemiology vol 181 no 12 pp 979ndash988 2015

[35] M P Rayman ldquoThe importance of selenium to human healthrdquoThe Lancet vol 356 no 9225 pp 233ndash241 2000

[36] E Fibach and E A Rachmilewitz ldquoThe role of antioxidantsand iron chelators in the treatment of oxidative stress inthalassemiardquo Annals of the New York Academy of Sciences vol1202 pp 10ndash16 2010

[37] A Fiesel M Ehrmann D K Gessner E Most and K EderldquoEffects of polyphenol-rich plant products from grape or hopas feed supplements on iron zinc and copper status in pigletsrdquoArchives of Animal Nutrition vol 69 no 4 pp 276ndash284 2015

[38] M Brnic R Wegmuller C Zeder G Senti and R F HurrellldquoInfluence of phytase EDTA and polyphenols on zinc absorp-tion in adults from porridges fortified with zinc sulfate or zincoxiderdquo Journal of Nutrition vol 144 no 9 pp 1467ndash1473 2014

[39] J Suliburska P Bogdanski M Szulinska M Stepien D Pupek-Musialik andA Jablecka ldquoEffects of green tea supplementationon elements total antioxidants lipids and glucose values in theserum of obese patientsrdquo Biological Trace Element Research vol149 no 3 pp 315ndash322 2012

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

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Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



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OphthalmologyJournal of


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Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom

Clinical StudyEffects of Dietary Strawberry Supplementation on AntioxidantBiomarkers in Obese Adults with Above Optimal Serum Lipids

Arpita Basu1 Stacy Morris1 Angel Nguyen1 Nancy M Betts1

Dongxu Fu2 and Timothy J Lyons23

1Department of Nutritional Sciences College of Human Sciences Oklahoma State University Stillwater OK 74078 USA2Centre for Experimental Medicine Queenrsquos University of Belfast Belfast BT7 1NN UK3Section of Diabetes amp Endocrinology University of Oklahoma Health Sciences Center Oklahoma City OK 73104 USA

Correspondence should be addressed to Arpita Basu arpitabasuokstateedu

Received 2 March 2016 Accepted 19 May 2016

Academic Editor Stan Kubow

Copyright copy 2016 Arpita Basu et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Berries have shown several cardiovascular health benefits and have been associated with antioxidant functions in experimentalmodels Clinical studies are limited We examined the antioxidant effects of freeze-dried strawberries (FDS) in adults [119899 = 60 age49 plusmn 10 years BMI 36 plusmn 5 kgm2 (mean plusmn SD)] with abdominal adiposity and elevated serum lipids Participants were randomizedto one of the following arms low dose strawberry (25 gday FDS) low dose control beverage (LD-C) high dose strawberry (50 gdFDS) and high dose control beverage (HD-C) for 12 weeks Control beverages were matched for calories and total fiber Plasmaantioxidant capacity trace elements (copper iron selenium and zinc) whole blood glutathione (GSH) and enzyme activity(catalase glutathione peroxidase and glutathione reductase) were examined at screening (0 week) and after 12 weeksrsquo interventionAt 12 weeks plasma antioxidant capacity and glutathione levels were higher in the strawberry versus control groups (low and highdose FDS 45 and 42 for plasma antioxidant capacity and 28 and 36 for glutathione resp) glutathione was higher in thehigh versus low dose strawberry group (all 119901 lt 005) Serum catalase activity was higher in the low dose strawberry (43) versuscontrol group (119901 lt 001) No differences were noted in plasma trace elements and glutathione enzyme activity Dietary strawberriesmay selectively increase plasma antioxidant biomarkers in obese adults with elevated lipids

1 Introduction

Dietary berries a rich source of bioactive compounds espe-cially the polyphenols have been associated with protectiveeffects against chronic diseases especially lowering risk fac-tors of cardiovascular disease (CVD) [1ndash3] Oxidative stress isone of themajor contributors to the pathophysiology of CVDand is triggered by many factors such as obesity elevatedserum lipids and low dietary and cellular antioxidant status[4 5] The antioxidant system is a complex network ofvarious biomolecules that individually and synergisticallycounteract free radicals and protect against oxidative damageThe antioxidant enzymes such as catalase and the superoxidedismutase (SOD) serve as first line defenses against hydrogenperoxide and superoxide anions respectively while the glu-tathione enzyme system counteracts the peroxide moleculesgenerated as by-products of dismutase activity and from the

oxidation of biomolecules that results in lipid peroxides [4]In addition to these antioxidant enzymes dietary micronu-trients such as vitamins C and E and trace elements suchas copper iron selenium and zinc also play an importantrole in antioxidant and pro-oxidant activities [6] Manypolyphenol-containing foods and beverages such as berriescocoa and green tea as well as their extracts have beenreported to enhance the activities of antioxidant enzymes andto chelate metal ions thereby improving oxidative stress [7ndash9] However few clinical studies have examined their effectsin adults with cardiovascular risk factors such as those withobesity dyslipidemia and the metabolic syndrome

Among the popular sources of dietary berries straw-berries have been shown to alleviate CVD risk factors inclinical studies as well as in animal models of atheroscle-rosis [10] However only a few studies have reported theireffects on antioxidant biomarkers especially on antioxidant

Hindawi Publishing CorporationJournal of Nutrition and MetabolismVolume 2016 Article ID 3910630 9 pageshttpdxdoiorg10115520163910630




2 Methods














3 Results










4 Discussion




Excluded (n = 6)


Randomized (n = 66)


LD-C (n = 17) HD-C (n = 16)(n = 17)


LD-FDS (25 gday)



































5 Conclusions



Competing Interests




Acknowledgments



References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of



















2 Methods














3 Results










4 Discussion




Excluded (n = 6)


Randomized (n = 66)


LD-C (n = 17) HD-C (n = 16)(n = 17)


LD-FDS (25 gday)



































5 Conclusions



Competing Interests




Acknowledgments



References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
























3 Results










4 Discussion




Excluded (n = 6)


Randomized (n = 66)


LD-C (n = 17) HD-C (n = 16)(n = 17)


LD-FDS (25 gday)



































5 Conclusions



Competing Interests




Acknowledgments



References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
























4 Discussion




Excluded (n = 6)


Randomized (n = 66)


LD-C (n = 17) HD-C (n = 16)(n = 17)


LD-FDS (25 gday)



































5 Conclusions



Competing Interests




Acknowledgments



References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















Excluded (n = 6)


Randomized (n = 66)


LD-C (n = 17) HD-C (n = 16)(n = 17)


LD-FDS (25 gday)



































5 Conclusions



Competing Interests




Acknowledgments



References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of













































5 Conclusions



Competing Interests




Acknowledgments



References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















References

















































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















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