Consumption of blueberry polyphenols reduces exercise-induced oxidative stress compared to vitamin C

The state of the science on the health benefits of blueberries: a perspective

Mounting evidence indicates that blueberry consumption is associated with a variety of health benefits. It has been suggested that regular consumption of blueberries can support and/or protect against cardiovascular disease and function, pre-diabetes and type 2 diabetes, and brain and cognitive function in individuals with health conditions and age-related decline. Further, mechanistic investigations highlight the role of blueberry anthocyanins in mediating these health benefits, in part through interactions with gut microbiota. Also, nutritional interventions with blueberries have demonstrated the ability to improve recovery following exercise-induced muscle damage, attributable to anti-inflammatory effects. Despite these advancements in blueberry health research, research gaps persist which affects the generalizability of findings from clinical trials. To evaluate the current state of knowledge and research gaps, a blueberry health roundtable with scientific experts convened in Washington, DC (December 6-7, 2022). Discussions centered around five research domains: cardiovascular health, pre-diabetes and diabetes, brain health and cognitive function, gut health, and exercise recovery. This article synthesizes the outcomes of a blueberry research roundtable discussion among researchers in these domains, offering insights into the health benefits of blueberries and delineating research gaps and future research directions.

Effects of Vaccinium berries (blueberries, cranberries and bilberries) on oxidative stress, inflammation, exercise performance, and recovery - a systematic review

Exercise-induced muscle damage is common in athletes and recreational exercisers and can lead to muscle soreness, weakness, and impaired muscle function. The precise mechanisms are unclear but oxidative stress and inflammation are thought to play a role. (Poly)phenols are substances abundant in Vaccinium berries that have been suggested to possess antioxidant and anti-inflammatory effects that could help improve exercise performance and/or recovery from exercise. The objective of this systematic review was to evaluate the benefits of Vaccinium berry supplementation on exercise performance and recovery, as well as on exercise-induced oxidative and inflammatory biomarkers in healthy individuals. A comprehensive search was conducted in PubMed, ProQuest Medline, Web of Science, Cochrane Library, and Scopus. Studies were included if the participants were healthy individuals who were supplemented with any Vaccinium berry or Vaccinium berry-based products in comparison to a control group. Of the 13 articles included in this review, no significant differences in the exercise performance were found and only one study reported benefits for markers of recovery. Interleukins and c-reactive protein were the most frequently reported biomarkers, but there was limited evidence that Vaccinium berry supplementation impacted them post-exercise. Most studies were of high quality and showed a low risk of bias. Vaccinium berry supplementation is not effective in modulating markers of exercise-induced inflammation and oxidative distress in healthy individuals; nevertheless, more studies are required to evaluate their effects on exercise performance and recovery in this population.

Exploring the Relationship between Micronutrients and Athletic Performance: A Comprehensive Scientific Systematic Review of the Literature in Sports Medicine

The aim of this systematic review is twofold: (i) to examine the effects of micronutrient intake on athletic performance and (ii) to determine the specific micronutrients, such as vitamins, minerals, and antioxidants, that offer the most significant enhancements in terms of athletic performance, with the goal of providing guidance to athletes and coaches in optimizing their nutritional strategies. The study conducted a systematic search of electronic databases (i.e., PubMed, Web of Science, Scopus) using keywords pertaining to micronutrients, athletic performance, and exercise. The search involved particular criteria of studies published in English between 1950 and 2023. The findings suggest that vitamins and minerals are crucial for an athlete's health and physical performance, and no single micronutrient is more important than others. Micronutrients are necessary for optimal metabolic body's functions such as energy production, muscle growth, and recovery, which are all important for sport performance. Meeting the daily intake requirement of micronutrients is essential for athletes, and while a balanced diet that includes healthy lean protein sources, whole grains, fruits, and vegetables is generally sufficient, athletes who are unable to meet their micronutrient needs due to malabsorption or specific deficiencies may benefit from taking multivitamin supplements. However, athletes should only take micronutrient supplements with the consultation of a specialized physician or nutritionist and avoid taking them without confirming a deficiency.

No effect of a dairy-based, high flavonoid pre-workout beverage on exercise-induced intestinal injury, permeability, and inflammation in recreational cyclists: A randomized controlled crossover trial

BACKGROUND

Submaximal endurance exercise has been shown to cause elevated gastrointestinal permeability, injury, and inflammation, which may negatively impact athletic performance and recovery. Preclinical and some clinical studies suggest that flavonoids, a class of plant secondary metabolites, may regulate intestinal permeability and reduce chronic low-grade inflammation. Consequently, the purpose of this study was to determine the effects of supplemental flavonoid intake on intestinal health and cycling performance.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled crossover trial was conducted with 12 cyclists (8 males and 4 females). Subjects consumed a dairy milk-based, high or low flavonoid (490 or 5 mg) pre-workout beverage daily for 15 days. At the end of each intervention, a submaximal cycling trial (45 min, 70% VO2max) was conducted in a controlled laboratory setting (23°C), followed by a 15-minute maximal effort time trial during which total work and distance were determined. Plasma samples were collected pre- and post-exercise (0h, 1h, and 4h post-exercise). The primary outcome was intestinal injury, assessed by within-subject comparison of plasma intestinal fatty acid-binding protein. Prior to study start, this trial was registered at ClinicalTrials.gov (NCT03427879).

RESULTS

A significant time effect was observed for intestinal fatty acid binding protein and circulating cytokines (IL-6, IL-10, TNF-α). No differences were observed between the low and high flavonoid treatment for intestinal permeability or injury. The flavonoid treatment tended to increase cycling work output (p = 0.051), though no differences were observed for cadence or total distance.

DISCUSSION

Sub-chronic supplementation with blueberry, cocoa, and green tea in a dairy-based pre-workout beverage did not alleviate exercise-induced intestinal injury during submaximal cycling, as compared to the control beverage (dairy-milk based with low flavonoid content).

Exertional heat stroke: nutritional considerations

NEW FINDINGS

What is the topic of this review? The potential role of nutrition in exertional heat stroke. What advances does it highlight? Certain nutritional and dietary strategies used by athletes and workers may exert a protective effect the pathophysiological processes of exertional heat stroke, whereas others may be detrimental. While current evidence suggests that some of these practices may be leveraged as a potential countermeasure to exertional heat stroke, further research on injury-related outcomes in humans is required.

ABSTRACT

Exertional heat stroke (EHS) is a life-threatening illness and an enduring problem among athletes, military servicemen and -women, and occupational labourers who regularly perform strenuous activity, often under hot and humid conditions or when wearing personal protective equipment. Risk factors for EHS and mitigation strategies have generally focused on the environment, health status, clothing, heat acclimatization and aerobic conditioning, but the potential role of nutrition is largely underexplored. Various nutritional and dietary strategies have shown beneficial effects on exercise performance and health and are widely used by athletes and other physically active populations. There is also evidence that some of these practices may dampen the pathophysiological features of EHS, suggesting possible protection or abatement of injury severity. Promising candidates include carbohydrate ingestion, appropriate fluid intake and glutamine supplementation. Conversely, some nutritional factors and low energy availability may facilitate the development of EHS, and individuals should be cognizant of these. Therefore, the aims of this review are to present an overview of EHS along with its mechanisms and pathophysiology, discuss how selected nutritional considerations may influence EHS risk focusing on their impact on the key pathophysiological processes of EHS, and provide recommendations for future research. With climate change expected to increase EHS risk and incidence in the coming years, further investigation on how diet and nutrition may be optimized to protect against EHS would be highly beneficial.

Promoting a pro-oxidant state in skeletal muscle: Potential dietary, environmental, and exercise interventions for enhancing endurance-training adaptations

Accumulating evidence now shows that supplemental antioxidants including vitamin C, vitamin E and N-Acetylcysteine consumption can suppress adaptations to endurance-type exercise by attenuating reactive oxygen and nitrogen species (RONS) formation within skeletal muscle. This emerging evidence points to the importance of pro-oxidation as an important stimulus for endurance-training adaptations, including mitochondrial biogenesis, endogenous antioxidant production, insulin signalling, angiogenesis and growth factor signaling. Although sustained oxidative distress is associated with many chronic diseases, athletes have, on average, elevated levels of certain endogenous antioxidants to maintain redox homeostasis. As a result, trained athletes may have a better capacity to buffer oxidants during and after exercise, resulting in a reduced oxidative eustress stimulus for adaptations. Thus, higher levels of RONS input and exercise-induced oxidative stress may benefit athletes in the pursuit of continuous endurance training redox adaptations. This review addresses why athletes should be looking to enhance exercise-induced oxidative stress and how it can be accomplished. Methods covered include high-intensity interval training, hyperthermia and heat stress, dietary antioxidant restriction and modified antioxidant timing, dietary antioxidants and polyphenols as adjuncts to exercise, and vitamin C as a pro-oxidant.

Different Food Sources of Fructose-Containing Sugars and Fasting Blood Uric Acid Levels: A Systematic Review and Meta-Analysis of Controlled Feeding Trials

BACKGROUND

Although fructose as a source of excess calories increases uric acid, the effect of the food matrix is unclear.

OBJECTIVES

To assess the effects of fructose-containing sugars by food source at different levels of energy control on uric acid, we conducted a systematic review and meta-analysis of controlled trials.

METHODS

MEDLINE, Embase, and the Cochrane Library were searched (through 11 January 2021) for trials ≥ 7 days. We prespecified 4 trial designs by energy control: substitution (energy-matched replacement of sugars in diets); addition (excess energy from sugars added to diets); subtraction (energy from sugars subtracted from diets); and ad libitum (energy from sugars freely replaced in diets) designs. Independent reviewers (≥2) extracted data and assessed the risk of bias. Grading of Recommendations, Assessment, Development, and Evaluation was used to assess the certainty of evidence.

RESULTS

We included 47 trials (85 comparisons; N = 2763) assessing 9 food sources [sugar-sweetened beverages (SSBs), sweetened dairy, fruit drinks, 100% fruit juice, fruit, dried fruit, sweets and desserts, added nutritive sweetener, and mixed sources] across 4 energy control levels in predominantly healthy, mixed-weight adults. Total fructose-containing sugars increased uric acid levels in substitution trials (mean difference, 0.16 mg/dL;  95% CI:  0.06-0.27 mg/dL;  P = 0.003), with no effect across the other energy control levels. There was evidence of an interaction by food source: SSBs and sweets and desserts increased uric acid levels in the substitution design, while SSBs increased and 100% fruit juice decreased uric acid levels in addition trials. The certainty of evidence was high for the increasing effect of SSBs in substitution and addition trials and the decreasing effect of 100% fruit juice in addition trials and was moderate to very low for all other comparisons.

CONCLUSIONS

Food source more than energy control appears to mediate the effects of fructose-containing sugars on uric acid. The available evidence provides reliable indications that SSBs increase and 100% fruit juice decreases uric acid levels. More high-quality trials of different food sources are needed. This trial was registered at clinicaltrials.gov as NCT02716870.

Effect of SunGold Kiwifruit and Vitamin C Consumption on Ameliorating Exercise-Induced Stress Response in Women

INTRODUCTION

Markers of oxidative and psychological stress are elevated during high-intensity exercise. Additionally, when energy intake does not match expenditure, women who actively participate in sports and exercise are at risk of developing menstrual dysfunction, infertility, and osteoporosis. Vitamin C is known to reduce exercise-induced stress. Here, this study investigates the efficacy of consuming vitamin C from SunGold kiwifruit compared to in isolation, in ameliorating exercise-induced stress in recreationally active women.

METHODS AND RESULTS

Ten eumenorrheic women are recruited in this crossover study and attended three exercise and one rest trial. In the exercise trials, participants consumed 300 mg vitamin C from kiwifruit or drink, or have a placebo drink, followed by 30-min exercise on a cycle ergometer at 60% power. During rest visit, participants sat quietly and consumed a placebo drink. Salivary uric acid (oxidative stress) and cortisol (psychological stress) are measured before and immediately after exercise for 2 h. Both vitamin C and kiwifruit reduced exercise-induced uric acid, immediately after exercise. Vitamin C drink continued to decrease uric acid for a further 30 min and slightly attenuated exercise-induced cortisol.

CONCLUSIONS

Consuming liquid vitamin C prior to high-intensity cycling appears more effective than eating kiwifruit, in ameliorating exercise-induced stress in recreationally active women of reproductive age.

Effects of Dietary Strategies on Exercise-Induced Oxidative Stress: A Narrative Review of Human Studies

Exhaustive exercise can induce excessive generation of reactive oxygen species (ROS), which may enhance oxidative stress levels. Although physiological levels are crucial for optimal cell signaling and exercise adaptations, higher concentrations have been demonstrated to damage macromolecules and thus facilitate detrimental effects. Besides single dosages of antioxidants, whole diets rich in antioxidants are gaining more attention due to their practicality and multicomponent ingredients. The purpose of this narrative review is to summarize the current state of research on this topic and present recent advances regarding the antioxidant effects of whole dietary strategies on exercise-induced oxidative stress in humans. The following electronic databases were searched from inception to February 2021: PubMed, Scope and Web of Science. Twenty-eight studies were included in this narrative review and demonstrated the scavenging effects of exercise-induced ROS generation, oxidative stress markers, inflammatory markers and antioxidant capacity, with only one study not confirming such positive effects. Although the literature is still scarce about the effects of whole dietary strategies on exercise-induced oxidative stress, the majority of the studies demonstrated favorable effects. Nevertheless, the protocols are still very heterogeneous and further systematically designed studies are needed to strengthen the evidence.

Efficacy of Popular Diets Applied by Endurance Athletes on Sports Performance: Beneficial or Detrimental? A Narrative Review

Endurance athletes need a regular and well-detailed nutrition program in order to fill their energy stores before training/racing, to provide nutritional support that will allow them to endure the harsh conditions during training/race, and to provide effective recovery after training/racing. Since exercise-related gastrointestinal symptoms can significantly affect performance, they also need to develop strategies to address these issues. All these factors force endurance athletes to constantly seek a better nutritional strategy. Therefore, several new dietary approaches have gained interest among endurance athletes in recent decades. This review provides a current perspective to five popular diet approaches: (a) vegetarian diets, (b) high-fat diets, (c) intermittent fasting diets, (d) gluten-free diet, and (e) low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diets. We reviewed scientific studies published from 1983 to January 2021 investigating the impact of these popular diets on the endurance performance and health aspects of endurance athletes. We also discuss all the beneficial and harmful aspects of these diets, and offer key suggestions for endurance athletes to consider when following these diets.

Acute Effects of Oatmeal on Exercise-Induced Reactive Oxygen Species Production Following High-Intensity Interval Training in Women: A Randomized Controlled Trial

High-intensity interval training (HIIT) has been demonstrated to increase the generation of reactive oxygen species (ROS). Therefore, strategies to mitigate excessive ROS productions could be useful to reduce the negative consequences of oxidative damage for health, as well as for physical, performances. The aim of this study was to investigate the acute effects of pre-exercise oatmeal consumption on exercise-induced ROS generation in young, healthy women. Thirty-four participants were randomly allocated in one of two groups: oatmeal prior to HIIT (oatmeal; n = 17) or HIIT alone (control; n = 17). Blood samples were obtained at pre-meal, pre-HIIT, immediately post-HIIT, and 15 min after HIIT. Electron paramagnetic resonance (EPR) spectroscopy was used to analyze the concentrations of ROS in the capillary blood. In addition, the blood glucose and blood lactate levels were measured. Immediately post-HIIT, the ROS generation in the oatmeal group was significantly lower in contrast to the control group (p < 0.05). A significant interaction effect of time × meal (p < 0.05; η² = 0.234) was detected from the pre-meal to 15 post-HIIT for ROS production. Moreover, significant differences in the blood glucose levels were observed between the groups at pre-HIIT and immediately post-HIIT (p < 0.05). In conclusion, the consumption of oatmeal before HIIT may mitigate exercise-induced ROS production.

Blueberry Consumption and Exercise: Gap Analysis Using Evidence Mapping

Objective: Strenuous muscular workouts can increase markers of inflammation that can potentially damage components of skeletal muscles. Blueberries contain a variety of nutrients and phytochemicals that have individually been related to reduction in oxidative stress and inflammation. The objective was to conduct a systematic overview using evidence mapping to identify research-dense and evidence gap areas that examine the impact of blueberry consumption on exercise performance and inflammatory markers in adults. Design: The authors searched Medline, Cochrane Central, and Commonwealth Agricultural Bureau for literature published between 1946 and September 2019. Abstracts and full-text publications were screened in duplicate for studies that evaluated outcomes related to metabolism, lipoprotein, muscle damage, markers of oxidative stress, inflammatory markers, or gait after participants consumed blueberries and were subjected to some form of exercise. Results: The authors found nine randomized controlled trials, one single-arm study, and one observational study that met the eligibility criteria. Inflammatory markers, F2-isoprostanes, and gait speed were the most frequently reported outcomes, with each one reported by at least three studies. Outcomes related to metabolism, lipoproteins, muscle damage, and most markers of oxidative stress and most gait-related outcomes were each reported by one study. Intervention trials were generally conducted with a small number of participants and the majority included mostly younger individuals. Using multivariate analysis, the sole observational study examined physical ability among participants who consumed higher doses of blueberries compared with participants who consumed a half cup of blueberries less than once a month. Conclusions: Evidence mapping found that further research in both randomized controlled trials and cohort studies examining the impact of blueberry consumption on exercise performance and inflammatory markers is needed to establish an association.

Nutritional interventions for reducing the signs and symptoms of exercise-induced muscle damage and accelerate recovery in athletes: current knowledge, practical application and future perspectives

PURPOSE

This review provides an overview of the current knowledge of the nutritional strategies to treat the signs and symptoms related to EIMD. These strategies have been organized into the following sections based upon the quality and quantity of the scientific support available: (1) interventions with a good level of evidence; (2) interventions with some evidence and require more research; and (3) potential nutritional interventions with little to-no-evidence to support efficacy.

METHOD

Pubmed, EMBASE, Scopus and Web of Science were used. The search terms 'EIMD' and 'exercise-induced muscle damage' were individually concatenated with 'supplementation', 'athletes', 'recovery', 'adaptation', 'nutritional strategies', hormesis'.

RESULT

Supplementation with tart cherries, beetroot, pomegranate, creatine monohydrate and vitamin D appear to provide a prophylactic effect in reducing EIMD. β-hydroxy β-methylbutyrate, and the ingestion of protein, BCAA and milk could represent promising strategies to manage EIMD. Other nutritional interventions were identified but offered limited effect in the treatment of EIMD; however, inconsistencies in the dose and frequency of interventions might account for the lack of consensus regarding their efficacy.

CONCLUSION

There are clearly varying levels of evidence and practitioners should be mindful to refer to this evidence-base when prescribing to clients and athletes. One concern is the potential for these interventions to interfere with the exercise-recovery-adaptation continuum. Whilst there is no evidence that these interventions will blunt adaptation, it seems pragmatic to use a periodised approach to administering these strategies until data are in place to provide and evidence base on any interference effect on adaptation.

Total Dietary Antioxidant Intake Including Polyphenol Content: Is it Capable to Fight against Increased Oxidants within the Body of Ultra-Endurance Athletes?

The role of dietary antioxidants on exhaustive exercise-induced oxidative stress has been well investigated. However, the contribution of total dietary antioxidant capacity on exogenous antioxidant defense and exercise performance has commonly been disregarded. The aims of the present investigation were to examine (i) the effects of dietary total antioxidant intake on body antioxidant mechanisms, and (ii) an exhaustive exercise-induced oxidative damage in ultra-endurance athletes. The study included 24 ultra-marathon runners and long-distance triathletes (12 male and 12 female) who underwent an acute exhaustive exercise test (a cycle ergometer (45 min at 65% VO₂max) immediately followed by a treadmill test (75% VO₂max to exhaustion). Oxidative stress-related biomarkers (8-isoprostaglandin F2alpha (8-iso PGF2a), total oxidant status (TOS, total antioxidant status (TAS)) in plasma were collected before and after exercise. Oxidative stress index was calculated to assess the aspect of redox balance. Blood lactate concentrations and heart rate were measured at the 3rd and 6th min after exercise. Dietary antioxidant intake was calculated using the ferric reducing ability of plasma (FRAP) assay. Dietary total antioxidant intake of the subjects was negatively correlated with pre-exercise TOS concentrations (rs = -0.641 in male, and rs = -0.741 in females) and post- vs. pre- (∆) 8-iso PGF2a levels (rs = -0.702 in male; p = 0.016, and rs = -0.682 in females; p = 0.024), and positively correlated with ∆ TAS concentrations (rs = 0.893 in males; p = 0.001, and rs = 0.769 in females; p = 0.002) and post- exercise lactate concentrations (rs = 0.795 for males; p = 0.006, and rs = 0.642 for females; p = 0.024). A positive meaningful (p = 0.013) interaction was observed between time at exhaustion and dietary antioxidant intake (rs = 0.692) in males, but not in females. In conclusion, the determination of total dietary antioxidant intake in ultra-endurance athletes may be crucial for gaining a better perspective on body antioxidant defense against exhaustive exercise-induced oxidative stress. However, the effects of dietary antioxidant on exercise performance and recovery rate needs further investigation.

Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis

Previous research on animals indicates flavonoid compounds have immunomodulatory properties; however, human research remains inconclusive. The aim of this systematic review was to assess the efficacy of dietary flavonoids on upper respiratory tract infections (URTIs) and immune function in healthy adults. A created search strategy was run against Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and EMBASE classic, CINAHL, and AMED. The returned studies were initially screened, and 2 reviewers independently assessed the remaining studies for eligibility against prespecified criteria. Fourteen studies, of 387 initially identified, were included in this review, and the primary outcome measure was the effect of flavonoids on URTI incidence, duration, and severity. Of the included studies, flavonoid supplementation ranged from 0.2 to 1.2 g/d. Overall, flavonoid supplementation decreased URTI incidence by 33% (95% CI: 31%, 36%) compared with control, with no apparent adverse effects. Sick-day count was decreased by 40% with flavonoid supplementation, although unclear. Differences in bio-immune markers (e.g., interleukin-6, tumor necrosis factor-α, interferon-γ, neutrophils) were trivial between the intervention and control groups during the intervention and after exercise when a postintervention exercise bout was included. These findings suggest that flavonoids are a viable supplement to decrease URTI incidence in an otherwise healthy population.

Effects of Laminaria japonica polysaccharides on exercise endurance and oxidative stress in forced swimming mouse model

Background

Polysaccharides are the major active ingredients responsible for the bioactivities of Laminaria japonica. However, the effects of L. japonica polysaccharides (LJP) on exercise endurance and oxidative stress have never been investigated. Therefore, this study was conducted to investigate the effects of LJP on exercise endurance and oxidative stress in a forced swimming mouse model. The animals were divided into four groups, namely the control (C), LJP-75, LJP-150, and LJP-300 groups, which received physiological saline and 75, 150, and 300 mg kg⁻¹ LJP, respectively, by gavage once a day for 28 days. This was followed by a forced swimming test and measurements of various biochemical parameters.

Results

LJP increased swimming time to exhaustion, the liver and muscle glycogen content, and levels of superoxide dismutase, glutathione peroxidase, and catalase in the serum, liver, and muscle, which were accompanied by corresponding decreases in the malondialdehyde (MDA) content of the same tissues. Furthermore, decreases in blood lactic acid and serum myeloperoxidase (MPO) levels were observed.

Conclusion

LJP enhanced exercise endurance and protected mice against exhaustive exercise-induced oxidative stress.

Exercise-induced oxidative stress and dietary antioxidants

Context:

Overproduction of reactive oxygen and nitrogen species during physical exercise, exercise induced oxidative stress and antioxidant supplementation is interesting and controversial concepts that have been considered during the past decades.

Evidence Acquisition:

In this review, we aimed to summarize current evidence in relation to antioxidant supplementation outcomes during exercise and physical activity. For this aim, we obtained relevant articles through searches of the Medline and PubMed databases between 1980 to 2013. Although major studies have indicated that antioxidants could attenuate biomarkers of exercise-induced oxidative stress and the use of antioxidant supplement is a common phenomenon among athletes and physically active people, there are some doubts regarding the benefits of these.

Results:

It seems that the best recommendations regarding antioxidants and exercise are having a balanced diet rich in natural antioxidants and phytochemicals.

Conclusions:

Regular consumption of various fresh fruits and vegetables, whole grains, legumes and beans, sprouts and seeds is an effective and safe way to meet all antioxidant requirements in physically active persons and athletes.

Protective effect of a hydroethanolic extract from Bowdichia virgilioides on muscular damage and oxidative stress caused by strenuous resistance training in rats

Background

Natural antioxidants can reduce oxidative damage caused by high-intensity resistance training (RT). We investigated the in vitro antioxidant potential of hydroethanolic extract (HEE) from Bowdichia virgilioides on muscular damage and oxidative stress in rats subjected to high-intensity RT.

Methods

Thirty-two male Wistar rats were divided into four experimental groups: 1) control group (CG), oral administration (P.O.) of vehicle; 2) trained group (TG), vehicle-treated with RT; 3) B. virgilioides untrained group (BVG), treated with B. virgilioides HEE (200 mg/kg P.O.); and 4) trained B. virgilioides group (TBVG), treated with B. virgiliodes HEE (200 mg/kg P.O.). All animals were habituated to the training apparatus for 1 week. CT and TBVG animals were subjected to the training protocol, which consisted of three sets of 10 repetitions with 75% of the load established using the one-repetition maximum, for four weeks. CG and BVG animals were manipulated and fixed to the apparatus three times a week with no load. Treatment with B. virgilioides HEE or vehicle treatment was initiated after 25 days of RT (5 days; one dose per day). At the end of the experiments, plasmatic and gastrocnemius samples from all groups were obtained for the assessment of lipid peroxidation and creatine kinase activity.

Results

Compared to TG rats, TBVG rats showed decreases in plasma and gastrocnemius tissue lipid peroxidation by 55.68% (p <0.0001) and 66.61% (p <0.0012), respectively. Further, compared to TG rats TBVG rats showed decreases in plasma and gastrocnemius tissue oxidative stress by 62.83% (p <0.0005) and 54.97% (p <0.0197), respectively.

Conclusions

B. virgilioides HEE treatment reduced markers of oxidative stress caused by high-intensity RT. Further, HEE treatment during training significantly reduced the markers of tissue damage.

Serum ferritin is an important inflammatory disease marker, as it is mainly a leakage product from damaged cells

"Serum ferritin" presents a paradox, as the iron storage protein ferritin is not synthesised in serum yet is to be found there. Serum ferritin is also a well known inflammatory marker, but it is unclear whether serum ferritin reflects or causes inflammation, or whether it is involved in an inflammatory cycle. We argue here that serum ferritin arises from damaged cells, and is thus a marker of cellular damage. The protein in serum ferritin is considered benign, but it has lost (i.e. dumped) most of its normal complement of iron which when unliganded is highly toxic. The facts that serum ferritin levels can correlate with both disease and with body iron stores are thus expected on simple chemical kinetic grounds. Serum ferritin levels also correlate with other phenotypic readouts such as erythrocyte morphology. Overall, this systems approach serves to explain a number of apparent paradoxes of serum ferritin, including (i) why it correlates with biomarkers of cell damage, (ii) why it correlates with biomarkers of hydroxyl radical formation (and oxidative stress) and (iii) therefore why it correlates with the presence and/or severity of numerous diseases. This leads to suggestions for how one might exploit the corollaries of the recognition that serum ferritin levels mainly represent a consequence of cell stress and damage.

Dietary advice for muscularity, leanness and weight control in Men's Health magazine: a content analysis

BACKGROUND

The dietary content of advice in men's lifestyle magazines has not been closely scrutinised.

METHODS

We carried out an analysis of such content in all 2009 issues (n = 11) of Men's Health (MH) focusing on muscularity, leanness and weight control.

RESULTS

Promotion of a mesomorphic body image underpinned advice to affect muscle building and control weight. Diet advice was underpinned by a strong pseudo-scientific discourse, with citation of expert sources widely used to legitimise the information. Frequently multiple dietary components were advocated within one article e.g. fat, omega-3 fatty acids, thiamine, zinc and high-glycaemic index foods. Furthermore advice would cover numerous nutritional effects, e.g. strengthening bones, reducing stress and boosting testosterone, with little contextualisation. The emphasis on attainment of a mesomorphic body image permitted promotion of slimming diets.Advice to increase calorie and protein intake to augment muscle mass was frequent (183 and 262 references, respectively). Such an anabolic diet was advised in various ways, including consumption of traditional protein foods (217 references) and sports foods (107 references), thereby replicating muscle magazines' support for nutritional supplements. Although advice to increase consumption of red meat was common (52 references), fish and non-flesh sources of protein (eggs, nuts & pulses, and soy products) together exceeded red meat in number of recommendations (206 references). Advice widely asserted micronutrients and phytochemicals from plant food (161 references) as being important in muscle building. This emphasis diverges from stereotypical gender-based food consumption patterns.Dietary advice for control of body weight largely replicated that of muscularity, with strong endorsement to consume fruits and vegetables (59 references), diets rich in nuts and pulses and fish (66 references), as well as specific micronutrients and phytochemicals (62 references). Notably there was emphasis on fat-burning, good fats and consumption of single foods, with relatively little mention of dietary restriction.

CONCLUSIONS

Despite the widespread use of scientific information to endorse dietary advice, the content, format and scientific basis of dietary content of MH leaves much to be desired. The dietary advice as provided may not be conducive to public health.

Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage

Background

Exercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise.

Methods

In a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA.

Results

A significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p = 0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery.

Conclusions

This study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise and blueberry consumption. These findings may benefit the sporting community who should consider dietary interventions that specifically target health and performance adaptation.

Effect of purple sweet potato leaves consumption on exercise-induced oxidative stress and IL-6 and HSP72 levels

The aim of this study was to evaluate the effects of purple sweet potato leaves (PSPL) consumption on oxidative stress markers in a healthy, nontrained, young male population after completing a running exercise protocol. A crossover design was applied, with 15 subjects participating in a two-step dietary intervention period. Each subject was given a high- (PSPL group) or low-polyphenol (control group) diet for 7 days with a 14-day washout period. After each dietary intervention period, all subjects performed 1 h of treadmill running at a speed corresponding to 70% of each subject's individual maximal oxygen uptake (V̇o2max). Blood samples were taken before exercise and at 0, 1, and 3 h after exercise. Compared with the control group, PSPL consumption significantly increased plasma total polyphenols concentration and total antioxidant power (i.e., the ferric-reducing ability of plasma) in the PSPL group. The markers of oxidative damage, plasma TBARS and protein carbonyl, significantly decreased. Plasma IL-6 concentration also decreased. However, no significant difference was found in HSP72 levels between the two groups. These findings indicate that consuming a high-polyphenol diet for 7 days can modulate antioxidative status and decrease exercise-induced oxidative damage and pro-inflammatory cytokine secretion.

Effect of daily fruit ingestion on angiotensin converting enzyme activity, blood pressure, and oxidative stress in chronic smokers

OBJECTIVE

This study examined whether, daily fruit (blueberries) consumption (250 g) for three weeks or acute fruit ingestion (250 g) would attenuate angiotensin converting enzyme (ACE) activity and reduce oxidative stress in chronic cigarette smokers.

METHODS

Twenty subjects were recruited and randomized into fruit or control groups. Blood samples and blood pressure were obtained at baseline and then pre and one hour post when subjects returned to the lab three weeks later. To examine acute effects, the fruit group immediately ingested 250 g of blueberries after returning and at least one hour prior to the post blood draw. Plasma samples were analyzed for ACE activity, F(2)- isoprostanes and lipid hydroperoxides (LH) as measures of oxidative stress, and ferric reducing ability of plasma (FRAP) as a measure of antioxidant potential. A 2 (treatment) x 3 (time) repeated measures ANOVA was used for statistical analysis. If interaction was significant, then Student's t-tests were used to further examine this relationship. For these comparisons, a Bonferroni adjustment was made with statistical significance set at P < 0.025.

RESULTS

The pattern of change between treatments was not significant for any variable except LH (P < 0.001).

CONCLUSION

This study indicates that LH are significantly reduced by daily fruit consumption, but not affected by acute ingestion. This finding could be one way in which fruit consumption contributes to prevention of cardiovascular disease.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Effect of pharmacological lowering of plasma urate on exercise-induced oxidative stress

Urate is a metabolic end product of purine metabolism that contributes about 66% of the antioxidant capacity of plasma. The objective of this study was to evaluate the importance of plasma urate as an antioxidant using pharmacological lowering and examining the impact on plasma antioxidant capacity and oxidative stress after intense exercise. Fifteen subjects ran for 45 min at approximately 80% VO2 max under the influence of probenecid (1 g/d) (PRO) or placebo (PLA) in a double-blind, crossover design. Blood samples obtained at baseline, pre-exercise, and immediately post-exercise were analyzed for F2-isoprostanes, lipid hydroperoxides (LHs), ferric-reducing ability of plasma (FRAP), urate, ascorbate (AA), and nitrite. A 2 (group)x2 (time) repeated-measures analysis of variance (ANOVA), one-way ANOVA, Tukey-Kramer multiple comparison tests, and Student's t tests were used for statistical analysis. PRO exhibited lowered urate and FRAP compared with baseline (p<or=0.05), and group effects existed for the exercise trials (p=0.023 and p<or=0.001, respectively) versus PLA. F2-isoprostanes, nitrite, and AA were increased after exercise (p=0.004, p=0.001, and p=0.003, respectively), but the pattern of change was not different between treatments. This study indicates that plasma markers of exercise-induced oxidative stress were not affected by below-normal physiological concentrations of urate and a diminished antioxidant capacity within the plasma compartment.

Behavioral and genoprotective effects of Vaccinium berries intake in mice

Studies have shown that supplementation with berries rich in anthocyanins are effective in reducing oxidative stress associated with aging, and are beneficial in reversing age-related neuronal and behavioral changes. However, there are few reports on other biological activities of these polyphenols, such as genoprotective effects. The present experiments were performed to study the possible effects of 30-day administration of a lyophilized extract of Vaccinium ashei berries on cognitive performance using step-down inhibitory avoidance, open-field habituation and elevated plus-maze tasks, as well as on DNA damage in the hippocampus and cerebral cortex. The present study showed that the extract significantly enhanced long-term memory in the inhibitory avoidance task, induced an increase in the number of crossings during open-field habituation and had an anxiolytic effect in the elevated plus-maze task. Moreover, the extract reduced oxidative DNA damage in brain tissue in vitro. These results suggest that supplementation with V. ashei berries to mice improves performance on memory tasks and has a protective effect on DNA damage, possibly due to the antioxidant activity of polyphenols, including anthocyanins.

Effect of resistance exercise and carbohydrate ingestion on oxidative stress

Some research studies have produced data indicating that resistance exercise induces oxidative stress, despite minimal increases in VO(2). These studies have primarily relied on oxidative stress markers with low sensitivity and debatable reliability. However, F(2)-isoprostanes as measured by gas chromatography mass spectrometry are considered to be a reliable and precise indicator of oxidative stress. Carbohydrate ingestion during exercise is associated with reduced levels of stress hormones, which may influence oxidative stress and plasma antioxidant potential. Therefore, the purpose of this study was to investigate the influence of carbohydrate ingestion during resistance training on F(2)-isoprostanes and plasma antioxidant potential. Thirty strength-trained subjects were randomized to carbohydrate (CHO) or placebo (PLA) groups that lifted weights for 2 h. Subjects received 10 ml kg(- 1) h(- 1) CHO (6%) or PLA beverages during the exercise. Blood and vastus lateralis muscle biopsy samples were collected before and after exercise and analyzed for cortisol as a marker of general stress, F(2)-isoprostanes as a measure of oxidative stress, and ferric reducing ability of plasma (FRAP) as a measure of antioxidant potential, and for muscle glycogen, respectively. Decreases in muscle glycogen content did not differ between CHO and PLA. Cortisol and FRAP increased significantly in CHO and PLA (P = 0.008 and 0.044, respectively), but the pattern of change was not different between groups. F(2)-isoprostanes were unaffected by exercise. These results indicate that exhaustive resistance exercise and carbohydrate ingestion have no effect on oxidative stress or plasma antioxidant potential in trained subjects.

Effect of alpha-tocopherol supplementation on plasma homocysteine and oxidative stress in highly trained athletes before and after exhaustive exercise

The interrelationship between physical exercise, antioxidant supplementation, oxidative stress and plasma levels of homocysteine (Hcy) has not been adequately examined. The purpose of this study was to examine the effect of 2 months of vitamin E supplementation (800 IU/day alpha-tocopherol) (E) or placebo (P) in 38 triathletes on plasma Hcy concentrations, antioxidant potential and oxidative stress. It was hypothesized that vitamin E supplementation would reduce plasma Hcy and oxidative stress markers compared to placebo. Blood samples were collected 1 day prior to the race, immediately postrace and 1.5 h postrace. Plasma alpha-tocopherol was 75% higher (P<.001) in E versus P prerace (24.1+/-1.1 and 13.8+/-1.1 micromol/L, respectively), and this group difference was maintained throughout the race. Cortisol was significantly increased in both E and P (P<.001), but there was no difference in the pattern of change. There were no significant time, group or interaction effects on plasma Hcy concentrations between E and P. Plasma F(2)-isoprostanes increased 181% versus 97% during the race in E versus P, and lipid hydroperoxides were significantly elevated (P=.009) 1.5 h postrace in E versus P. Plasma antioxidant potential was significantly higher 1.5 h postrace in E versus P (P=.039). This study indicates that prolonged large doses of alpha-tocopherol supplementation did not affect plasma Hcy concentrations and exhibited pro-oxidant characteristics in highly trained athletes during exhaustive exercise.