Physical activity, aerobic capacity and selected markers of oxidative stress and the anti-oxidant defence system in healthy active elderly men

Contribution of Physical Activity to the Oxidative and Antioxidant Potential in 60-65-Year-Old Seniors

Both acute exercise and regular physical activity (PA) are directly related to the redox system. However, at present, there are data suggesting both positive and negative relationships between the PA and oxidation. In addition, there is a limited number of publications differentiating the relationships between PA and numerous markers of plasma and platelets targets for the oxidative stress. In this study, in a population of 300 participants from central Poland (covering the age range between 60 and 65 years), PA was assessed as regards energy expenditure (PA-EE) and health-related behaviors (PA-HRB). Total antioxidant potential (TAS), total oxidative stress (TOS) and several other markers of an oxidative stress, monitored in platelet and plasma lipids and proteins, were then determined. The association of PA with oxidative stress was determined taking into the account basic confounders, such as age, sex and the set of the relevant cardiometabolic factors. In simple correlations, platelet lipid peroxides, free thiol and amino groups of platelet proteins, as well as the generation of superoxide anion radical, were inversely related with PA-EE. In multivariate analyses, apart from other cardiometabolic factors, a significant positive impact of PA-HRB was revealed for TOS (inverse relationship), while in the case of PA-EE, the effect was found to be positive (inverse association) for lipid peroxides and superoxide anion but negative (lower concentration) for free thiol and free amino groups in platelets proteins. Therefore, the impact of PA may be different on oxidative stress markers in platelets as compared to plasma proteins and also dissimilar on platelet lipids and proteins. These associations are more visible for platelets than plasma markers. For lipid oxidation, PA seems to have protective effect. In the case of platelets proteins, PA tends to act as pro-oxidative factor.

The Influence of an Eight-Week Cycloergometer-Based Cardiac Rehabilitation on Serum Antioxidant Status in Men with Coronary Heart Disease: A Prospective Study

Background and objectives: A body of evidence confirms the benefits of cardiac rehabilitation (CR) in coronary heart disease (CHD) patients, but it remains unclear whether it enhances the antioxidant potential. The aim of the study was to assess the influence of an eight-week aerobic cycloergometer-based CR program on serum total antioxidant capacity (TAC) and other CHD risk factors. Materials and Methods: The study involved 36 men with CHD (55.2 ± 9.0 years). TAC was assessed with two methods: ferric reducing ability of serum (TAC-FRAS) and 2.2-diphenyl-1-picryl-hydrazyl (TAC-DPPH). Aerobic capacity was evaluated during a submaximal exercise test. TAC and other anthropometric, biochemical and physical activity/fitness measures were performed twice: before the beginning and after termination of CR. Results: Aerobic capacity was higher (7.0 ± 2.6 vs. 8.0 ± 2.5 MET—metabolic equivalents; p < 0.01), but values of resting diastolic blood pressure were lower (81.9 ± 7.6 vs. 77.4 ± 8.9 mmHg; p < 0.01) after termination of CR. Other classic cardiometabolic, anthropometric, and biochemical measures did not change with CR. No difference in TAC-FRAS was found after CR, whereas TAC-DPPH was significantly lower (16.4 ± 4.0 vs. 13.2 ± 3.7% reduction; p < 0.01). Conclusions: Antioxidant potential measured as TAC-DPPH, but not as TAC-FRAS, decreased with the CR program. The recognized health benefits of CR are not related to augmented serum antioxidant status.

The Effects of a Community-Based Exercise Program on Function and Health in Older Adults: The EnhanceFitness Program

This study examined the effectiveness of participation in EnhanceFitness (EF) (formerly the Lifetime Fitness Program), an established community-based group exercise program for older adults. EF incorporated performance and health status measure testing in year 2000. Initial performance was compared to age and gender-based norms to classify participants as within or at or above normal limits (WNL) or below (BNL). In 2,889 participants who participated in outcomes testing, improvements were observed at 4 and 8 months on performance tests for both subgroups. Participants’ self-rating of health improved at 8 months. All participants improved on performance tests. Implementation of performance-based measures in community studies is possible. Challenges included selecting measures, staff training, collecting performance measures, and deciding on time points for data collection. Older adults can maintain and/or improve physical function through participation in EnhanceFitness.

Physical Activity, Aerobic Capacity, and Total Antioxidant Capacity in Healthy Men and in Men with Coronary Heart Disease

OBJECTIVE

The purpose of the study was to assess total antioxidant capacity (TAC) of blood serum in relation with habitual leisure time physical activity (LTPA) and aerobic capacity in a group of 90 men with coronary heart disease (CHD) aged 34.8-77.0 years and in 90 age-matched peers without CHD.

METHODS

Two spectrophotometric methods were applied to assess TAC: Ferric Reducing Ability of Serum (TAC-FRAS) and 2.2-diphenyl-1-picryl-hydrazyl (TAC-DPPH) tests. Aerobic capacity was expressed as physical working capacity at 85% of the maximal heart rate (PWC(85%HRmax)).

RESULTS

CHD patients had higher values of TACFRAS (1.37 ± 0.28 versus 1.27 ± 0.23 mmol FeCl2·L(-1); P < 0.05) but there were no group differences for TAC-DPPH and for uric acid (UA). Negative correlation was found between LTPA (also when calculated per kg of body mass) and TAC-DPPH in CHD patients. In CHD patients, TAC-FRAS and UA were lower in subjects with higher aerobic capacity expressed as PWC(85%HRmax/kg). Those associations were not found in healthy men.

CONCLUSIONS

We conclude that TAC of blood serum is moderately adversely related to LTPA and aerobic capacity in patients with CHD. UA, as the main determinant of serum TAC, may be partially responsible for those associations.

Green tea extract supplementation does not hamper endurance-training adaptation but improves antioxidant capacity in sedentary men

The purpose of this study was to investigate the effect of green tea extract (GTE) supplementation combined with endurance training on endurance capacity and performance in sedentary men. Forty untrained men (age: 20 ± 1 years) participated in this study. Subjects were assigned to 1 of 4 treatments: (i) placebo-control (CTRL), (ii) GTE, (iii) endurance training (Ex), and (iv) endurance training with GTE (ExGTE). During the 4-week intervention, exercise training was prescribed as 75% oxygen uptake reserve for three 20-min sessions per week, and either GTE (250 mg/day) or placebo was provided. Endurance capacity, malondialdehyde (MDA), total antioxidant status (TAS), and creatine kinase (CK) were examined. Ex and ExGTE but not GTE improved exhaustive-run time (Ex: +8.2%, p = 0.031; ExGTE: +14.3%, p < 0.001); in addition, Ex and ExGTE significantly increased maximal oxygen uptake by ∼14% (p = 0.041) and ∼17% (p = 0.017) above the values of the CTRL group, respectively. Both Ex and ExGTE significantly decreased the increase of CK by ∼11%-32% below that of CTRL following an exhaustive run (Ex: p = 0.007; ExGTE: p = 0.001). Moreover, TAS levels increased by ∼11% in ExGTE after training (p = 0.040), and GTE, Ex, and ExGTE markedly attenuated exercise-induced MDA production (p = 0.01, p = 0.005, p = 0.011, respectively). In conclusion, this investigation demonstrated that daily ingestion of GTE during endurance training does not impair improvements in endurance capacity. Moreover, endurance training combined with GTE not only increases antioxidant capacity without attenuating endurance training adaptations, but also further attenuates acute exercise-induced CK release.

Markers of oxidative stress and erythrocyte antioxidant enzyme activity in older men and women with differing physical activity

The aim of the present study was to examine the relationship between markers of oxidative stress and erythrocyte antioxidant enzyme activity and physical activity in older men and women. The present study included 481 participants (233 men and 248 women) in the age group 65-69 years (127 men and 125 women) and in the age group 90 years and over (106 men and 123 women). The classification of respondents by physical activity was based on answers to the question if, in the past 12 months, they engaged in any pastimes which require physical activity. The systemic oxidative stress status was assessed by measuring plasma iso-PGF2α and protein carbonyl concentration as well as erythrocyte antioxidant enzymes activity, i.e., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). The concentration of plasma iso-PGF2α and protein carbonyls (CP) was lower in groups of younger men and women compared to the respective older groups. In all examined groups, physical activity resulted in decrease of these oxidative stress markers and simultaneously caused adaptive increase in the erythrocyte SOD activity. Additionally, in active younger men CAT, GPx, and GR activities were higher than in sedentary ones. In conclusion, oxidative stress increase is age-related, but physical activity can reduce oxidative stress markers and induce adaptive increase in the erythrocyte antioxidant enzyme activity, especially SOD, even in old and very old men and women.

Chrononutrition against oxidative stress in aging

Free radicals and oxidative stress have been recognized as important factors in the biology of aging and in many age-associated degenerative diseases. Antioxidant systems deteriorate during aging. It is, thus, considered that one way to reduce the rate of aging and the risk of chronic disease is to avoid the formation of free radicals and reduce oxidative stress by strengthening antioxidant defences. Phytochemicals present in fruits, vegetables, grains, and other foodstuffs have been linked to reducing the risk of major oxidative stress-induced diseases. Some dietary components of foods possess biological activities which influence circadian rhythms in humans. Chrononutrition studies have shown that not only the content of food, but also the time of ingestion contributes to the natural functioning of the circadian system. Dietary interventions with antioxidant-enriched foods taking into account the principles of chrononutrition are of particular interest for the elderly since they may help amplify the already powerful benefits of phytochemicals as natural instruments with which to prevent or delay the onset of common age-related diseases.

Physical activity and total antioxidant capacity across an adult lifespan of men

PURPOSE

The aim of the study was to determine the association between the long-term physical activity (PA) and the total antioxidant capacity (TAC) of blood serum and their association with coexisting risk factors of cardiometabolic diseases in a group of relatively healthy men.

METHODS

The research was conducted among 422 males age 19.2-89.8 yr, either sedentary or involved in recreational sports activities. Anthropometric measurements, lipid profile, and measurement of glucose and uric acid levels were performed in every man. Current PA, historical PA, and aerobic fitness (physical working capacity) were assessed. TAC was determined with two spectrophotometric methods: the ferric reducing ability of serum (TAC-FRAS) and 2,2-diphenyl-1-picryl-hydrazyl (TAC-DPPH) tests.

RESULTS

TAC was not related to the age of the subjects. Higher current and historical PA were associated with a more favorable cardiometabolic risk profile but not TAC. In fact, current PA level was connected with lower values of TAC-FRAS. Values of both TAC-FRAS and TAC-DPPH decreased with an increase of aerobic capacity. Individuals with coexisting anthropometric and biochemical risk factors of cardiovascular diseases and with elevated values of arterial pressure had higher TAC. Values of both TAC-FRAS (r = 0.66) and TAC-DPPH (r = 0.39) were strongly positively correlated with uric acid level.

CONCLUSIONS

Overweight, obesity, higher blood pressure, unfavorable blood lipid profile, and especially higher uric acid levels are connected with greater TAC of blood serum across an adult man's life. High PA and fitness are associated with a more favorable overall risk profile of cardiovascular and metabolic diseases but are related to lower TAC.

Psoriasis and physical activity: a review

Psoriasis is a common, chronic inflammatory skin disease that can cause significant discomfort and impairment to quality of life. Recent research indicates that individuals with moderate-to-severe psoriasis are likely at greater risk for chronic cardiometabolic co-morbidities such as cardiovascular disease, type 2 diabetes, obesity and metabolic syndrome. Physical activity can be an effective primary and adjunctive treatment for these maladies in other populations. Unfortunately, only a limited number of studies have examined physical activity in psoriasis, which are limited by poor design and lack of validated physical activity assessment methodologies. A variety of data suggest shared physiologic pathways between physical activity, psoriasis, and psoriasis cardiometabolic co-morbidities. Increased adiposity, inflammation, oxidative stress, adhesion molecules and lipids are physiologically linked to psoriasis, the risk of psoriasis cardiometabolic co-morbidities, and low levels of physical activity. In addition, epigenetic pathways are involved in psoriasis and could be influenced by physical activity. The physical and psychosocial impairments common in psoriasis may make it difficult to participate in regular physical activity, and future studies should aim to determine if physical activity interventions improve functioning and reduce co-morbidities in psoriasis.

Age-Related Blood Antioxidant Capacity in Men and Women

The aim of the study was to assess the blood antioxidant capacity in men and women in relation to age. The subjects were 19 men (YM) and 19 women (YW) aged 25-32 years, and 11 men (OM) and 11 women (OW) aged 63-71 years, all sedentary. The following factors were determined: the activity of erythrocyte superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPX), catalase (CAT), total antioxidant status (TAS), as well as plasma retinol, α-tocopherol, uric acid and total protein concentrations. The sum of standardized activities of antioxidant enzymes was calculated to compare age-related changes in the total capacity of the erythrocyte antioxidant defense. No significant age-related changes in SOD activity were observed; mean CAT activity was higher in older women and men than in younger subjects. Mean activity of GPX was higher and that of GR lower in older subjects compared to the younger ones. The calculated total erythrocyte antioxidant enzyme capacity in younger and older subjects rendered similar values. No significant differences in plasma retinol and α-tocopherol concentrations in relation to sex or age were noted. The plasma total protein level was significantly lower in younger women and men compared to their older mates. It was concluded that the total erythrocyte enzymatic antioxidant capacity did not change with age. The results obtained clearly show that multiple factors may contribute to the ageing process.

Effect of an antioxidant functional food beverage on exercise-induced oxidative stress: a long-term and large-scale clinical intervention study

The efficacy of long-term intake of a novel functional food supplement Funciona™ containing vitamins and juiced fruits was evaluated in order to assess the net effect of physical activity and antioxidant potentials in healthy older adult population. The long-term (2 years) and large-scale (400 older adult subjects) interventional study was based on both moderate-intensity exercise practice and concurrent supplementation. Sustained exercise-induced oxidative stress as reflected in significantly increased blood thiobarbituric acid-reactive substances (TBARS) (+15%), protein carbonyl groups (PC) (+18%) and oxidized glutathione (GSSG) (+112%) concentrations, and leukocyte 8-OHdG contents (23%). Exercise decreased the reduced/oxidized glutathione (GSH/GSSG) molar ratio (-43%) and plasma vitamin C levels (-22%). Supplementation with Funciona™ was significant in preventing oxidative damage to lipid, protein and DNA, and normalizing blood GSSG, GSH/GSSG and vitamin C levels. Thus daily intake of the antioxidant functional beverage counteracts the exercise-induced oxidative stress in free-living older subjects, and might be necessary to restore impaired antioxidant balance due long-term regular exercise.

Age- and gender-related oxidative status determined in healthy subjects by means of OXY-SCORE, a potential new comprehensive index

Oxidative stress has been related to various diseases, gender and ageing, and has been measured by various markers. The authors developed a procedure to compute a global oxidative stress index (OXY-SCORE), reflecting both oxidative and antioxidant markers in healthy subjects. Its performance was tested in relation to age and gender and in coronary artery disease (CAD) patients. Eighty-two healthy subjects and 20 CAD patients were enrolled. Plasma free and total malondialdehyde (F- and T-MDA), glutathione disulphide/reduced form ratio (GSSG/GSH) and urine isoprostanes (iPF2alpha-III) levels were combined as oxidative damage markers (damage score). GSH, alpha- and gamma-tocopherol (TH) levels, and individual antioxidant capacity were combined as antioxidant defence indexes (protection score). The OXY-SCORE was computed by subtracting the protection score from the damage score. Among single parameters, T-MDA and iPF2alpha-III significantly correlated with age; only GSH and both tocopherols correlated with male gender in healthy subjects. The OXY-SCORE was positively associated with age (p=0.004) and male gender (p=0.03). As expected, the OXY-SCORE was higher in CAD with a very significant p-value (<0.0001), after adjusting for age, gender and smoking. Combining different markers can potentially provide a powerful index in the evaluation of oxidative stress related to age, gender and CAD status.

Atherogenic inflammatory and oxidative stress markers in relation to overweight values in male former athletes

OBJECTIVE

To evaluate inflammation- and oxidative stress-related (OxS) background in former athletes in relation to overweight and abdominal obesity status.

DESIGN

Cross-sectional data from ongoing follow-up study.

SUBJECTS

A total of 60 middle-aged former athletes (46.6+/-7.5 years; 181.1+/-7.2 cm; 88.1 +/- 12.9 kg) and 54 age-matched controls (48.1+/-7.3 years; 181.4 +/- 6.2 cm; 89.7 +/- 14.4 kg).

MEASUREMENTS

Anthropometric characteristics, serum lipoproteins (CHOL, HDL-C, LDL-C, TG), oxidized LDL (oxLDL), diene conjugates (DC) and high-sensitive C-reactive protein (hsCRP). Information about the physical activity and other lifestyle variables were collected by the questionnaire.

RESULTS

Ex-athletes were characterized by significantly higher physical activity characteristics and lower CHOL and oxLDL in comparison with controls. Correlation analysis among ex-athletes revealed negative associations between all measured overweight data (body mass index, fat percentage, waist to hip circumferences and waist circumference (WC)), and current physical activity. Current physical activity was significantly related to OxS and inflammatory characteristics (oxLDL, DC and hsCRP) among the ex-athletes, but not among the control group. The most expressed positive correlations were found between WC, hsCRP, triglycerides (TG), DC and oxLDL in both study groups.

CONCLUSION

Our study results suggest that there exists an independent (adjusted for potential confounders) association between overweight, abdominal obesity, and atherogenic inflammatory and oxidative stress markers in ex-athletes as well as in age-matched controls. Major findings of our study show that WC is the best correlate of hsCRP, oxLDL, DC and TG levels.

High-sensitive C-reactive protein level and oxidative stress-related status in former athletes in relation to traditional cardiovascular risk factors

OBJECTIVE

To analyze systemic and cellular oxidative stress-related indices as well as C-reactive protein level in former top-level athletes in relation to traditional cardiovascular risk factors.

METHODS

A cross-sectional study was performed in 53 former male athletes and 25 sedentary controls (age range: 39-59 years). We measured anthropometric factors (BMI, fat percentage, WHR), resting blood pressure (SBP, DBP), serum cholesterol (CHOL), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglycerides (TG), total antioxidant status (TAS), oxidized LDL-C (oxLDL), diene conjugates (DC), glutathione redox status, high-sensitive C-reactive protein (hsCRP), and leisure-time physical activity.

RESULTS

Physically active former athletes had significantly lower mean overweight (BMI, fat percentage, WHR), better spectrum of atherogenesis indicators (CHOL, HDL-C, TG, TG:HDL-C ratio) and lower oxidative stress (oxLDL, oxLDL:LDL-C ratio, DC) values than sedentary ex-athletes. No significant differences in these variables were found between the sedentary ex-athletes and control group. Significant associations were found between physical activity (METs), SBP, DBP, hypertension, CHOL, HDL-C, TG, TG:HDL-C ratio, oxLDL, oxLDL:LDL-C ratio, DC and hsCRP.

CONCLUSIONS

A physically active lifestyle is related to a lower cardiovascular disease (CVD) risk profile including a substantially lower systemic and cellular oxidative stress status as well as C-reactive protein level in middle-aged men.

Plasma glutathione peroxidase in healthy young adults: influence of gender and physical activity

OBJECTIVES

Oxidative stress is implicated in the pathophysiology of many cardiovascular diseases. Plasma glutathione peroxidase (pl x GPx, GPx3) is an antioxidant enzyme found in the extracellular fluid. This study aimed to determine reference values for serum GPx3 concentration and GPx activity in young healthy males and females of similar aerobic fitness and to determine the impact of acute physical activity on serum GPx.

DESIGN AND METHODS

52 young, healthy but not physically trained subjects (24 male, 28 female; age = 20.4 +/- 0.7 yr, cycling VO(2 max) = 39.2 +/- 1.6 mL/kg/min; mean +/- SE) participated in this study. An independent group of 18 subjects participated in an acute, 90 min bout of 50% VO(2 max) cycling exercise. Serum GPx activity and GPx3 protein levels, as well as estradiol and 8-iso- prostaglandin F(2alpha) (8-iso-PGF(2alpha;) an index of lipid peroxidation) were determined.

RESULTS

Females had significantly higher serum GPx3 concentration (29.1 +/- 1.6 vs. 24.2 +/- 1.3 mg/L, p < 0.01) and serum GPx activity (256.4 +/- 10.4 vs. 222.8 +/- 15.6 U/L, p < 0.05) than males; specific activity (U/mg) was not different between genders. There was no significant gender difference in 8-iso-PGF(2alpha). No significant correlation was found between either GPx activity or GPx3 concentration and serum estradiol or VO(2)(max). The acute, prolonged, mild intensity exercise did not affect serum GPx activity or 8-iso-PGF(2a) levels in males or females.

CONCLUSIONS

The results of this study suggest that in a young, healthy but not physically well-trained population females are endowed with slightly higher serum GPx3 concentrations and GPx activities than males, but the functional significance of this has not been established. Furthermore, the results indicate that serum GPx levels are not associated with aerobic fitness level, or serum estradiol concentration and that acute, prolonged, mild exercise does not affect the activity of serum GPx in this population.

Influence of ageing, heat shock treatment and in vivo total antioxidant status on gene-expression profile and protein synthesis in human peripheral lymphocytes

Ageing results in a progressive, intrinsic and generalised imbalance of the control of regulatory systems. A key manifestation of this complex biological process includes the attenuation of the universal stress response. Here we provide the first global assessment of the ageing process as it affects the heat shock response, utilising human peripheral lymphocytes and cDNA microarray analysis. The genomic approach employed in our preliminary study was supplemented with a proteomic approach. In addition, the current study correlates the in vivo total antioxidant status with the age-related differential gene expression as well as the translational kinetics of heat shock proteins (hsps). Most of the genes encoding stress response proteins on the 4224 element microarray used in this study were significantly elevated after heat shock treatment of lymphocytes obtained from both young and old individuals albeit to a greater extent in the young. Cell signaling and signal transduction genes as well as some oxidoreductases showed varied response. Results from translational kinetics of induction of major hsps, from 0 to 24 h recovery period were broadly consistent with the differential expression of HSC 70 and HSP 40 genes. Total antioxidant levels in plasma from old individuals were found to be significantly lower by comparison with young, in agreement with the widely acknowledged role of oxidant homeostasis in the ageing process.

Exercise-induced oxidative stress in older adults as a function of habitual activity level

OBJECTIVES

It has been suggested that regular physical activity might maintain and promote the antioxidant defense capacity against oxidative stress. Therefore, we assessed exercise-induced oxidative stress in relation to habitual physical activity level (PAL) in older adults.

DESIGN

The study included a 2-week observation period for the measurement of average daily metabolic rate (ADMR) and PAL. Exercise-induced oxidative stress was measured during a 45-minute cycling test at submaximal intensity.

SETTING

A university medical research center.

PARTICIPANTS

Twenty-six subjects volunteered for the study (n = 26; mean age +/- standard deviation 60 +/- 1; body mass index 27 +/- 1 kg/m2).

MEASUREMENTS

PAL was determined as ADMR combined with a measurement of basal metabolic rate (BMR): PAL = ADMR/BMR. ADMR was measured over 2 weeks with the doubly labeled water method, preceded by a BMR measurement with a ventilated hood. Antipyrine oxidation was used as marker for oxidative stress in vivo. Reaction of antipyrine with hydroxyl radicals results in the formation of para-hydroxyantipyrine (p-APOH) and ortho-hydroxyantipyrine (o-APOH), where o-APOH is not formed through alternative oxygenetic pathways.

RESULTS

PAL was inversely related to the exercise-induced increase in the ratio of o-APOH to native antipyrine (r = 0.49, P = .010). The relationship between PAL and exercise-induced increase in the ratio of p-APOH (r = 0.30, P = .140) or thiobarbituric acid reactive species (r = 0.31, P = .130) did not reach the level of significance.

CONCLUSION

Physically active older adults have a reduced exercise-induced oxidative stress than older adults with a lower level of physical activity. It seems that regular physical activity improves the antioxidant defense capacity.

Oxidants and antioxidative defense

The role of oxygen free radicals and other oxidants in several diseases has been well established over the past decade. Whereas it was long known that high doses of oxidants may damage or kill cells, the effect of low doses or long-time exposure to small flux rates of oxidants have been the focus of the free radical research until now. Here one has to take into account that most physiological and pathophysiological actions of oxidants and free radicals are based on the permanent action of small doses and flux rates. This includes effects of oxidants on signal transduction pathways and gene expression patterns. Therefore, only a few answers can be given today on the relevance of the effects of low doses of oxidants.

Oxidative stress and cardiovascular disease in type 2 diabetes: the role of antioxidants and pro-oxidants

Oxidative stress occurs when there is an imbalance between free radical production and antioxidant capacity. This may be due to increased free radical formation in the body and/or loss of normal antioxidant defenses. Oxidative stress has been associated with the development of cardiovascular disease. The role of antioxidants in the primary and secondary prevention of coronary heart disease is currently under study. Although epidemiologic evidence indicates that antioxidants may decrease cardiovascular risk, clinical trial data are not conclusive. Information regarding the use and benefits of antioxidants in persons with diabetes is limited. Persons with diabetes may be more prone to oxidative stress because hyperglycemia depletes natural antioxidants and facilitates the production of free radicals. In addition, other factors such as homocysteine, insulin resistance, and aging may be contributory. This article highlights landmark clinical trials that have examined the cardioprotective effect of antioxidants. Because these trials have not been designed to study persons with diabetes, and clinical trial data for this group are not available, correlational studies are also presented. Finally, the concept of oxidative stress, the antioxidant and pro-oxidant factors that may contribute to oxidative stress, and the consequences of oxidative stress in persons with type 2 diabetes are presented. Key words: antioxidants, clinical trials,

Issues surrounding age: vascular disease in the elderly

One-fifth of all humans who have survived beyond the age of 65 are alive today, and in the industrialized world the elderly segment of the population is expanding most rapidly. In biological terms, these survivors are healthier than the elderly of previous generations. However 'there are no diseases peculiar to old age and very few from which it is exempt' (Alfred Worcester, 1855-1951), and so society will inevitably accumulate a significant share of degenerative diseases within the ranks of its senior citizens. In the last two decades, the prevalence of stroke, diabetes mellitus, arthritis and heart disease has increased significantly as a tangible index of ageing in the population, and these diseases have been accompanied by degenerating cognitive function and physical disability, both of which are adding increasing stress to community healthcare and social services. Policy-makers need to understand and monitor these trends in order to make informed and cogent decisions about the management of this growing problem. This review highlights some of the key health issues facing the elderly in regard to coronary artery disease, insulin resistance, redox status, and statin therapy, in the hope that enlightened debate will inform decision making on resource allocation for this important and growing segment of society.