Strawberry Supplementation Research Articles

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Comment on Krikorian et al. Early Intervention in Cognitive Aging with Strawberry Supplementation. Nutrients 2023, 15, 4431.

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Early Intervention in Cognitive Aging with Strawberry Supplementation.

Late-life dementia is a growing public health concern lacking effective treatment. Neurodegenerative disorders such as Alzheimer's disease (AD) develop over a preclinical period of many years beginning in midlife. The prevalence of insulin resistance, a prominent risk factor for late-life dementia, also accelerates in middle-age. Consumption of berry fruits, including strawberries, has been shown to influence metabolism as well as cognitive performance suggesting potential to mitigate risk for dementia. In this controlled trial, we enrolled overweight middle-aged men and women with insulin resistance and subjective cognitive decline and performed a 12-week intervention with daily administration of whole-fruit strawberry powder. Diet records showed that participants in both groups maintained the prescribed abstinence from berry product consumption outside the study. We observed diminished memory interference (p = 0.02; Cohen's f = 0.45) and a reduction of depressive symptoms (p = 0.04; Cohen's f = 0.39) for the strawberry-treated participants; benefits consistent with improved executive ability. However, there was no effect of the intervention on metabolic measures, possibly a consequence of the sample size, length of the intervention, or comparatively low anthocyanin dose. Anti-inflammatory actions of anthocyanins were considered as a primary mechanistic factor. The findings support the notion that strawberry supplementation has a role in dementia risk reduction when introduced in midlife. However, further investigation with longer intervention periods, larger samples, and differing dosing regimens will be required to assess the benefits of strawberry intake with respect to cognition and metabolic function in the context of aging.

Gut Microbes Are Associated with the Vascular Beneficial Effects of Dietary Strawberry on Metabolic Syndrome-Induced Vascular Inflammation.

Metabolic syndrome (MetS) alters the gut microbial ecology and increases the risk of cardiovascular disease. This study investigates whether strawberry consumption reduces vascular complications in an animal model of MetS and identifies whether this effect is associated with changes in the composition of gut microbes. Seven-week-old male mice consume diets with 10% (C) or 60% kcal from fat (high-fat diet fed mice; HF) for 12 weeks and subgroups are fed a 2.35% freeze-dried strawberry supplemented diet (C+SB or HF+SB). This nutritional dose is equivalent to ≈160 g of strawberry. After 12 weeks treatment, vascular inflammation is enhanced in HF versus C mice as shown by an increased monocyte binding to vasculature, elevated serum chemokines, and increased mRNA expression of inflammatory molecules. However, strawberry supplementation suppresses vascular inflammation in HF+SB versus HF mice. Metabolic variables, blood pressure, and indices of vascular function were similar among the groups. Further, the abundance of opportunistic microbe is decreased in HF+SB. Importantly, circulating chemokines are positively associated with opportunistic microbes and negatively associated with the commensal microbes (Bifidobacterium and Facalibaculum). Dietary strawberry decreases the abundance of opportunistic microbe and this is associated with a decrease in vascular inflammation resulting from MetS.

Dietary Strawberries Lower Branched Chain Amino Acids in Adults With the Metabolic Syndrome in Targeted Serum Metabolomics Analyses

ObjectivesDietary berries have been shown to lower cardio-metabolic risks in clinical trials. We examined the dose-response effects of two dietary achievable doses of strawberries on serum metabolomics related to energy metabolism in adults with metabolic syndrome. MethodsIn this 14-week randomized controlled crossover study adults with metabolic syndrome were assigned to one of the three arms for 4 weeks separated by a one-week washout period: control powder, one serving strawberries (13 g powder/day), and 2.5 servings strawberries (32 g powder/day). The freeze-dried powders were blended in water and participants consumed half the daily dose in the morning and half in the evening. Participants were instructed to follow their usual diet and lifestyle while refraining from consuming other berries and related products throughout the study. Metabolic profiling was performed using a high-throughput serum nuclear magnetic resonance (NMR) metabolomics platform (West Coast Metabolomics Center, UC Davis, USA). ResultsThirty-three participants completed all three phases of the trial (baseline profiles: weight: 90.8 ± 22.4 kg, BMI: 33.1 ± 4.2 kg/m2, waist circumference: 109 ± 12.5 cm, HbA1c:5.8 ± 0.2%). Outcome measures were analyzed using a multivariate analysis of variance with statistical significance set at p < 0.05. Among the targeted primary metabolites, strawberry supplementation at a dose of 2.5 servings per day for 4 weeks significantly decreased the circulating concentrations of branched chain amino acids (valine and leucine) as targeted primary metabolites in the study (P < 0.05). No effects were noted on isoleucine, alanine, and other metabolites of the citric acid cycle. ConclusionsThese branched chain amino acids are increased in individuals with obesity and are associated with insulin resistance or type 2 diabetes. These data suggest that consuming strawberries at two and half servings for four weeks significantly improves metabolomic profiles related to insulin resistance in adults with the metabolic syndrome. Funding SourcesCalifornia Strawberry Commission and NIH COBRE.

Does strawberry supplementation ameliorate markers of cardiovascular and metabolic health? A systematic review and meta-analysis

PurposeThis study aims to identify the effect of strawberry supplementation on some metabolic, inflammatory and oxidative parameters in adults with cardiovascular (CV) risk factors.Design/methodology/approachA systematic literature search was performed up to November 2020 using PubMed, Embase, Cochrane, Web of Sciences and Scopus databases. The pooled mean difference (MD) with 95% confidence interval (CI) was used to analyze the data by random-effects model. I2 statistics and Cochrane risk of bias tool were used for investigating heterogeneity and quality of included studies, respectively.FindingsIn total, 13 randomized controlled trials with 488 participants were included. Strawberry supplementation significantly reduced diastolic blood pressure (MD = −2.1, 95% CI [−3.7, −0.42], P = 0.01), low-density lipoprotein cholesterol (−0.16, −0.30, −0.02, P = 0.03), high-sensitivity C-reactive protein (CRP) (−0.76, −1.4, −0.05, P < 0.001) and CRP (−0.31, −0.43, −0.18, P = 0.04). Leptin levels were raised in control group compared with participants who had received strawberry (0.65, 0.09 and 1.2, P = 0.02). The results of subgroup analysis based on the follow-up duration and supplementation dose showed that consumption of strawberry for more than eight weeks and 50 g day−1 can significantly decrease some other CV risk factors compared to control group. Further, both higher follow-up duration and supplementation dose were more effective in increasing leptin levels of control group compared to intervention group.Originality/valueThe use of some useful plant foods such as strawberries by the pharmaceutical industry and the community health sector can greatly help improve people’s CV and metabolic health.

Randomized Double-Blind Controlled Trial of Freeze-Dried Strawberry Powder Supplementation in Adults with Overweight or Obesity and Elevated Cholesterol

Objective Recommended dietary patterns improve cardiovascular disease (CVD) risk factors such as blood pressure and LDL-C, as well as emerging markers that confer residual risk. Strawberry consumption has been shown to improve CVD risk factors, but further research is needed to better understand these effects using a dose-response model that evaluates a standard serving and a higher (but still achievable) dose. Methods A randomized, placebo-controlled, double-blinded crossover trial was conducted in middle-aged adults with overweight or obesity (n = 40; mean BMI = 29.4 ± 0.2 kg/m2; mean age = 50 ± 1.0 years) and moderately elevated LDL-C (mean LDL-C: 140 ± 3 mg/dL) to investigate the effect of two doses of strawberry supplementation on LDL-C and other CVD risk factors. Study interventions were: 0 g/d (control), 13 g/d (low-dose), and 40 g/d (high-dose) of freeze-dried strawberry powder (4-week supplementation periods separated by a 2-week compliance break). Results There was a significant main effect of treatment for the primary outcome of LDL-C, with a 4.9% reduction following the low-dose strawberry supplement compared to the high-dose (P = 0.01), but not compared to the control. There was also a significant effect on total cholesterol (TC), with a 2.8% and 2.4% reduction following the low-dose compared to the control and high-dose, respectively (P ≤ 0.05 in post-hoc analyses). There was a near significant effect for direct LDL-C (P = 0.07). There were no significant treatment effects for other atherogenic lipoprotein characteristics, indices of vascular function, measures of inflammation, or HDL efflux. Conclusion Low-dose supplementation with freeze-dried strawberry powder, equivalent to ∼1 serving/day of fresh strawberries, improved cholesterol in adults with overweight or obesity, compared to both the high-dose (∼3 servings/day of fresh strawberries) and control, but did not alter other markers of CVD. Supplemental data for this article is available online at

Dose-Response Effects of Strawberries on Atherogenic Lipoproteins: A Randomized Controlled Crossover Trial

Abstract Objectives Previous research indicates that consumption of strawberries may provide benefits for reduction of atherogenic lipoproteins but has not identified an optimal dose. Our objective was to evaluate effects of 2 doses of strawberry powder, approximately equivalent to 1 and 3 servings of strawberries per day, on serum lipoprotein concentrations. Methods Middle-aged adults (n = 40, age 49 ± 1 year) with elevated LDL-C (140 ± 4 mg/dL) and elevated BMI (29.4 ± 0.4 kg/m2) consumed 0 g/d (control), 13 g/d (low-dose), and 40 g/d (high-dose) of freeze-dried strawberry powder in a randomized crossover design (4-week supplementation periods separated by a 2 week compliance break). Fasting blood samples were obtained on two separate days (and averaged) at study-entry baseline and following each supplementation period. Results There were significant main effects of treatment (P ≤ 0.05) for calculated LDL-C, nonHDL-C, and total cholesterol (TC). In post hoc tests, the low-dose resulted in 5% lower LDL-C vs. the high-dose (P = 0.01), 4% lower nonHDL-C vs. control (P = 0.04), and 3% lower TC for the low-dose vs. control and high-dose (P ≤ 0.04). Compared to baseline, low-dose strawberry supplementation also significantly reduced direct LDL-C (−6.8 mg/dL, P = 0.02), but there was not a main effect of treatment. Conclusions Our results suggest that low-dose supplementation with freeze dried strawberry powder, roughly equivalent to one serving of strawberries per day, was superior to high-dose supplementation for improving atherogenic lipoproteins in overweight adults. Funding Sources California Strawberry Commission.

Effect of Endurance Exercise Along with Strawberry Supplementation on Lipid Profile and Inflammatory Markers in Overweight and Inactive Young Women

Background: Herbal supplementation with moderate- and high-intensity aerobic exercise affects obesity-related factors, especially the lipid profile and inflammatory markers. Objectives: The present study was conducted to determine the effect of endurance training with strawberry extract supplementation on inflammatory markers and the lipid profile in healthy inactive women. Methods: The subjects included inactive women aged 20 - 30 years, who were randomly divided into two groups: (a) The endurance exercise + supplementation group (n = 12) and (b) The endurance exercise + placebo group (n = 12). The supplementation group received 100-mg strawberry extract supplement twice per day for two weeks. After the supplementation, the exercise protocol was carried out, which included a session of endurance exercise within 75% - 80% of the maximum heart rate on the treadmill for 30 minutes. Blood samples were taken before and after the intervention to determine the lipid profile and plasma fibrinogen concentration. Data were analyzed using the repeated-measures ANOVA. Results: The results showed a significant reduction in TC, TG and LDL-C and a significant increase in HDL-C after the supplementation, but no significant changes were observed in the placebo group. Fibrinogen concentrations decreased significantly following the supplementation. Meanwhile, no significant increase was observed in the groups after the endurance exercise (P ≤ 0.05). Conclusions: According to the results obtained and the benefits of dried strawberry powder on cardiovascular risk factor control, supplementation following exercise training are recommended for improving the physiological function of inactive people who are prone to dyslipidemia and inflammation.

Polyphenol Consumption on Human Bile Acids Metabolism: Preliminary Data of Bile Acid Profiles in Human Biological Samples (P06-131-19)

ObjectivesBile acids (BAs) play a critical role in regulating human health through the activation of BAs receptor farnesoid X receptor (FXR) and membrane G protein coupled bile acid receptor-1 (TGR5). We aimed to develop methods to characterize BAs and their metabolites in human biological samples and characterize changes in BAs profile after chronic polyphenol consumption to help guide investigations on the potential health effects of polyphenols via BAs metabolism. MethodsPlasma, fecal and urine samples from two human studies that included berry intake were used for developing qualitative analysis of BAs using ultra high-performance liquid chromatography (UHPLC) coupled with electrospray ionization quadrupole time of flight (QTOF). The compounds were identified based on the exact mass, fragmentation pattern, available reference standards and database search. To investigate the effect of chronic polyphenol consumption on BAs composition, pooled plasma samples (fasting and postprandial 2 h, n = 6) from a chronic (45 and 90 days) strawberry supplementation study (24 g freeze dried/day) with an older population were analyzed. ResultsAmong 106 BAs and their metabolites which were tentatively identified in the samples used for method development, 70, 55, and 47 BAs species were characterized in plasma, feces and urine samples, respectively. The qualitative analysis of BAs in plasma samples from subjects following the strawberry consumption protocol detected 8 primary and 31 secondary BAs. After 90-days strawberry supplementation, two secondary BAs–glycolithocholic acid and 9(11), (5β)-cholenic acid-3α, 12α-diol were decreased to undetectable levels in the pooled fasting sample and the FRX/TGR5 agonists, including chenodeoxycholic acid, deoxycholic acid, cholic acid, glycodeoxycholic acid and taurocholic acid, showed increasing peak areas at 2 h postprandial compared to fasting. ConclusionsThe changes in BAs profiles in fasting and postprandial plasma samples after chronic strawberry feeding suggest that strawberry polyphenols may alter BAs metabolism and the FXR/TGR5 signaling. Funding SourcesThis work was funded by the California Strawberry Commission, USDA Intramural Funds and various donor funds to the Center for Nutrition Research, IIT.

Dietary supplementation with strawberry induces marked changes in the composition and functional potential of the gut microbiome in diabetic mice

Gut microbiota contributes to the biological activities of berry anthocyanins by transforming them into bioactive metabolites, and anthocyanins support the growth of specific bacteria, indicating a two-way relationship between anthocyanins and microbiota. In the present study, we tested the hypothesis that strawberry supplementation alters gut microbial ecology in diabetic db/db mice. Control (db/+) and diabetic (db/db) mice (7 weeks old) consumed standard diet or diet supplemented with 2.35% freeze-dried strawberry (db/db + SB) for 10 weeks. Colon contents were used to isolate bacterial DNA. V4 variable region of 16S rRNA gene was amplified. Data analyses were performed using standardized pipelines (QIIME 1.9 and R packages). Differences in predictive metagenomics function were identified by PICRUSt. Principal coordinate analyses confirmed that the microbial composition was significantly influenced by both host genotype and strawberry consumption. Further, α-diversity indices and β-diversity were different at the phylum and genus levels, and genus and operational taxonomical units levels, respectively (P<.05). At the phylum level, strawberry supplementation decreased the abundance of Verrucomicrobia in db/db + SB vs. db/db mice (P<.05). At the genus level, db/db mice exhibited a decrease in the abundance of Bifidobacterium, and strawberry supplementation increased Bifidobacterium in db/db + SB vs. db/db mice (P<.05). PICRUSt revealed significant differences in 45 predicted metabolic functions among the 3 groups. Our study provides evidence for marked changes in the composition and functional potential of the gut microbiome with strawberry supplementation in diabetic mice. Importantly, strawberry supplementation increased the abundance of beneficial bacteria Bifidobacterium which play a pivotal role in the metabolism of anthocyanins.

Effects of strawberry supplementation on cardiovascular risk factors: a comprehensive systematic review and meta-analysis of randomized controlled trials.

Cardiovascular disease (CVD) is the greatest cause of premature death and disability globally. Consequently, numerous therapeutic strategies have been developed in order to prevent the onset of adverse cardiovascular events including nutritional approaches. This includes strawberries as they have a high oxidant and micronutrient content, so we examined the extent to which dietary supplementation impacts on CVD risk factors. A comprehensive literature search without any limitation on language was conducted using the following bibliographical databases: ISI Web of Science, Scopus, PubMed and Cochrane Library. Search was conducted between 1985 and February 2019. The mean difference (MD) of the reported effects was calculated using a random effect model. A total of 20 groups from 14 clinical trials were included for final analysis. The pooled effect size showed that strawberry supplementation decreased circulating oxidized LDL (MD = -5.8 ng ml-1, p = 0.012), malondialdehyde (0.309 μmol L-1, p = 0.002), C-reactive protein (MD = -0.472 mg L-1, p = 0.003), total cholesterol (MD = -6.49 mg dL-1, p = 0.019), and diastolic blood pressure (MD = -2.220 mmHg, p = 0.033). It also demonstrated raised fasting blood sugar (MD = 2.083 mg dl-1; p = 0.040), but had no effect on other CVD risk factors examined. Dietary supplementation with strawberries improved specific CVD risk factors, suggesting that larger well-designed, adequately powered, and longer-term follow up studies should now be undertaken.

Circulating metabolites of strawberry mediate reductions in vascular inflammation and endothelial dysfunction in db/db mice

BackgroundCardiovascular disease is 2-4-fold more prevalent in patients with diabetes. Human studies support the cardiovascular benefits of strawberry consumption but the effects of strawberry on diabetic vasculature are unknown. We tested the hypothesis that dietary strawberry supplementation attenuates vascular inflammation and dysfunction in diabetic mice. MethodsSeven-week-old diabetic db/db mice that consumed standard diet (db/db) or diet supplemented with 2.35% freeze-dried strawberry (db/db + SB) for ten weeks were compared to non-diabetic control mice (db/+). Indices of vascular inflammation and dysfunction were measured. Endothelial cells (ECs) were isolated from the vasculature to determine the influence of strawberry on them. The effect of metabolites of strawberry on endothelial inflammation was determined by incubating mouse aortic ECs (MAECs) with ±5% serum, obtained from strawberry fed mice (metabolites serum) or standard diet fed mice (control serum) ± 25 mM glucose and 100 μM palmitate. Resultsdb/db mice exhibited an increased monocyte binding to vessel, elevated blood pressure, and reduced endothelial-dependent vasorelaxation compared with db/+ mice but each defect was attenuated in db/db + SB mice. The elevation of inflammatory molecules, NOX2 and inhibitor-κB kinase observed in ECs from db/db vs. db/+ mice was suppressed in db/db + SB mice. Glucose and palmitate increased endothelial inflammation in MAECs but were normalized by co-incubation with metabolites serum. ConclusionsDietary supplementation of strawberry attenuates indices of vascular inflammation and dysfunction in diabetic db/db mice. The effect of strawberry on vasculature is endothelial-dependent and possibly mediated through their circulating metabolites. Strawberry might complement conventional therapies to improve vascular complications in diabetics.

Strawberry consumption improves aging-associated impairments, mitochondrial biogenesis and functionality through the AMP-activated protein kinase signaling cascade

Dietary polyphenols have been recently proposed as activators of the AMP-activated protein kinase (AMPK) signaling pathway and this fact might explain the relationship between the consumption of polyphenol-rich foods and the slowdown of the progression of aging. In the present work, the effects of strawberry consumption were evaluated on biomarkers of oxidative damage and on aging-associated reductions in mitochondrial function and biogenesis for 8weeks in old rats. Strawberry supplementation increased antioxidant enzyme activities, mitochondrial biomass and functionality, and decreased intracellular ROS levels and biomarkers of protein, lipid and DNA damage (P<0.05). Furthermore, a significant (P<0.05) increase in the expression of the AMPK cascade genes, involved in mitochondrial biogenesis and antioxidant defences, was also detected after strawberry intake. These in vivo results were then verified in vitro on HepG2 cells, confirming the involvement of AMPK in the beneficial effects exerted by strawberry against aging progression.

Strawberry Supplementation Lessens Vascular Inflammation and Dysfunction Displayed by Diabetic db/db Mice

BackgroundCardiovascular disease is 2–4 fold more prevalent in patients with diabetes. In diabetes high glucose induced vascular inflammation and the subsequent endothelial dysfunction leads to the development of atherosclerosis. Human studies have shown that the consumption of strawberries (SB) improves cardiovascular risk but the effects of SB on diabetic vasculature are unknown. We sought to determine whether dietary strawberry supplementation attenuates vascular inflammation and dysfunction in diabetic db/db mice.MethodsSeven‐week old male diabetic db/db mice that consumed standard chow (db/db) or chow supplemented with 2.35% freeze‐dried strawberries (db/db+SB) for 10 weeks were compared to non‐diabetic control mice (db/+). Based on normalization to body surface area, the SB dose is equivalent to two human servings of SB (~160 g) per day. In vivo assessments at ~17 weeks included body weight and food intake, glucose (GTT), and insulin (ITT) tolerance, and systemic arterial blood pressure (tail cuff). Ex vivo analyses included arterial inflammation (monocyte binding to aortic endothelium), endothelial cell (EC) inflammation (mRNA expression of inflammatory cytokines in carotid artery ECs), and mesenteric arterial reactivity (isometric tension procedures).ResultsCompared to db/+ animals, both diabetic groups displayed similar increases (p&lt;0.05) in weight gain and impairments (p&lt;0.05) in glucose and insulin tolerance. Arterial pressure (systolic, diastolic, and mean) was higher (p&lt;0.05) in db/db vs. db/+ mice, but the severity of hypertension was attenuated (p&lt;0.05) in db/db+SB mice. Relaxation to acetylcholine (ACh; 10−8‐10−6 M) in arteries precontracted with ~ 10−6 M phenylephrine was impaired (p&lt;0.05) in db/db mice vs. db/+ animals, but no differences existed between db/db+SB vs. db/+ mice. Vasorelaxation to sodium nitroprusside (10−9‐10−4 M) was complete and similar among groups. Mouse monocyte WEHI 78/24 cells exhibited higher (p&lt;0.05) binding to the aortic endothelium of db/db vs. db/+ mice, but this response was attenuated (p&lt;0.05) in aortic endothelium from db/db+SB mice. Consistent with these findings, relative to results obtained from db/+ animals, elevations of MCP‐1/JE and KC expression were greater (p&lt;0.05) in carotid artery ECs from db/db but were suppressed in db/db+SB mice.ConclusionDietary supplementation of strawberries attenuates indices of diabetes‐induced vascular dysfunction without altering glucose and insulin tolerance. This study provides proof of concept for further considering strawberries as an adjunct therapy to improving vascular complications associated with diabetes.Support or Funding InformationSupported by University of Utah Seed Grant and the College of Health Research Pilot Grant.

The Protective Properties of the Strawberry (Fragaria ananassa) against Carbon Tetrachloride-Induced Hepatotoxicity in Rats Mediated by Anti-Apoptotic and Upregulation of Antioxidant Genes Expression Effects.

The strawberry (Fragaria ananassa) has been extensively used to treat a wide range of ailments in many cultures. The present study was aimed at evaluating the hepatoprotective effect of strawberry juice on experimentally induced liver injury in rats. To this end, rats were introperitoneally injected with carbon tetrachloride (CCl4) with or without strawberry juice supplementation for 12 weeks and the hepatoprotective effect of strawberry was assessed by measuring serum liver enzyme markers, hepatic tissue redox status and apoptotic markers with various techniques including biochemistry, ELISA, quantitative PCR assays and histochemistry. The hepatoprotective effect of the strawberry was evident by preventing CCl4-induced increase in liver enzymes levels. Determination of oxidative balance showed that strawberry treatment significantly blunted CCl4-induced increase in oxidative stress markers and decrease in enzymatic and non-enzymatic molecules in hepatic tissue. Furthermore, strawberry supplementation enhanced the anti-apoptotic protein, Bcl-2, and restrained the pro-apoptotic proteins Bax and caspase-3 with a marked reduction in collagen areas in hepatic tissue. These findings demonstrated that strawberry (F. ananassa) juice possessed antioxidant, anti-apoptotic and anti-fibrotic properties, probably mediated by the presence of polyphenols and flavonoids compounds.

Dietary Strawberry Improves Cognition in Older adults: A Randomized, Double‐Blind, Placebo‐Controlled Trial

Older adults experience a variety of functional changes that decrease their quality of life with age‐related cognitive decline and reduced mobility being of particular concern. Pre‐clinical research indicates that berry fruit offer a promising dietary approach to preserving nervous system function, in part due to the antioxidant and anti‐inflammatory properties of their polyphenolic compounds. Based on the improvements in mobility and cognition observed among strawberry‐supplemented aged rats, we hypothesized that dietary supplementation with strawberry would also benefit older adults. The present study investigated the effects of strawberry supplementation (24g/day, ≈2 cups/day fresh strawberry) or placebo powder on healthy older men and women (60–75 years old). Motor and cognitive ability were assessed at days 0, 45, and 90 of supplementation. Improvements in hippocampally‐mediated word recognition and spatial memory were observed among participants that consumed strawberry, relative to placebo; however, no effects on mobility were observed. These findings suggest that the inclusion of strawberry in the diet may aid in preserving aspects of cognitive function during aging.Support or Funding InformationUSDA Intramural, California Strawberry Commission

Effects of Dietary Strawberry Supplementation on Antioxidant Biomarkers in Obese Adults with Above Optimal Serum Lipids.

Berries have shown several cardiovascular health benefits and have been associated with antioxidant functions in experimental models. Clinical studies are limited. We examined the antioxidant effects of freeze-dried strawberries (FDS) in adults [n = 60; age: 49 ± 10 years; BMI: 36 ± 5 kg/m2 (mean ± SD)] with abdominal adiposity and elevated serum lipids. Participants were randomized to one of the following arms: low dose strawberry (25 g/day FDS), low dose control beverage (LD-C), high dose strawberry (50 g/d FDS), and high dose control beverage (HD-C) for 12 weeks. Control beverages were matched for calories and total fiber. Plasma antioxidant 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 weeks' intervention. At 12 weeks, plasma antioxidant capacity and glutathione levels were higher in the strawberry versus control groups (low and high dose FDS: 45% and 42% for plasma antioxidant capacity and 28% and 36% for glutathione, resp.); glutathione was higher in the high versus low dose strawberry group (all p < 0.05). Serum catalase activity was higher in the low dose strawberry (43%) versus control group (p < 0.01). No differences were noted in plasma trace elements and glutathione enzyme activity. Dietary strawberries may selectively increase plasma antioxidant biomarkers in obese adults with elevated lipids.

Chilean Strawberry Consumption Protects against LPS-Induced Liver Injury by Anti-Inflammatory and Antioxidant Capability in Sprague-Dawley Rats.

The Chilean strawberry fruit has high content of antioxidants and polyphenols. Previous studies evidenced antioxidant properties by in vitro methods. However, the antioxidant effect and its impact as functional food on animal health have not been evaluated. In this study, rats were fed with a Chilean strawberry aqueous extract (4 g/kg of animal per day) and then subjected to LPS-induced liver injury (5 mg/kg). Transaminases and histological studies revealed a reduction in liver injury in rats fed with strawberry aqueous extract compared with the control group. Additionally, white strawberry supplementation significantly reduced the serum levels and gene expression of TNF-α, IL-6, and IL-1β cytokines compared with nonsupplemented rats. The level of F2-isoprostanes and GSH/GSSG indicated a reduction in liver oxidative stress by the consumption of strawberry aqueous extract. Altogether, the evidence suggests that dietary supplementation of rats with a Chilean white strawberry aqueous extract favours the normalization of oxidative and inflammatory responses after a liver injury induced by LPS.

Doxorubicin-Induced Oxidative Stress in Rats Is Efficiently Counteracted by Dietary Anthocyanin Differently Enriched Strawberry (Fragaria × ananassa Duch.)

This study investigated the effects of two different strawberry cultivars, Adria and Sveva, against doxorubicin (DOX)-induced toxicity in rats. A controlled dietary intervention was conducted over 16 weeks with four groups: (i) normal diet; (ii) normal diet + DOX injection; (iii) Adria supplementation + DOX injection; and (iv) Sveva supplementation + DOX injection. Sveva presented higher total antioxidant capacity value and phenol and and vitamin C levels than Adria, which in turn presented higher anthocyanin contents. DOX drastically increased lymphocyte DNA damage, liver biomarkers of protein and lipid oxidation, and mitochondrial ROS content and markedly decreased plasma retinol level, liver antioxidant enzymes, and mitochondrial functionality. After 2 months of strawberry supplementation, rats presented a significant reduction of DNA damage and ROS concentration and a significant improvement of oxidative stress biomarkers, antioxidant enzyme activities, and mitochondrial performance. These results suggest that strawberry supplementation can counteract DOX toxicity, confirming the potential health benefit of strawberry in vivo against oxidative stress.