Effect of supplementation with antioxidants upon long-term risk of hypertension in the SU.VI.MAX study: association with plasma antioxidant levels

Reactive oxygen species in hypertension

Hypertension is a leading risk factor for stroke, heart disease and chronic kidney disease. Multiple interacting factors and organ systems increase blood pressure and cause target-organ damage. Among the many molecular elements involved in the development of hypertension are reactive oxygen species (ROS), which influence cellular processes in systems that contribute to blood pressure elevation (such as the cardiovascular, renal, immune and central nervous systems, or the renin-angiotensin-aldosterone system). Dysregulated ROS production (oxidative stress) is a hallmark of hypertension in humans and experimental models. Of the many ROS-generating enzymes, NADPH oxidases are the most important in the development of hypertension. At the cellular level, ROS influence signalling pathways that define cell fate and function. Oxidative stress promotes aberrant redox signalling and cell injury, causing endothelial dysfunction, vascular damage, cardiovascular remodelling, inflammation and renal injury, which are all important in both the causes and consequences of hypertension. ROS scavengers reduce blood pressure in almost all experimental models of hypertension; however, clinical trials of antioxidants have yielded mixed results. In this Review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in hypertension. We focus on cellular sources of ROS, molecular mechanisms of oxidative stress and alterations in redox signalling in organ systems, and their contributions to hypertension.

The Role of Oxidative Stress in Hypertension: The Insight into Antihypertensive Properties of Vitamins A, C and E

Hypertension stands as a pervasive global health challenge, contributing significantly to mortality rates worldwide. Various factors, including lifestyle choices and dietary habits, contribute to the development of hypertension. In recent years, oxidative stress has garnered significant attention as a factor influencing hypertension risk, prompting a shift in research focus towards exploring it as a potential target for prevention and treatment. Antioxidants found in our diet, such as vitamins C, E and carotenoids exhibit the ability to neutralize reactive oxygen species, thereby mitigating oxidative stress. In addition, Vitamin A has an antioxidant effect despite not being an antioxidant itself. Consequently, supplementation or increased intake of these antioxidants has been hypothesized to potentially lower blood pressure levels and aid in the management of hypertension, thereby potentially prolonging life expectancy. Research findings regarding this effect have been diverse. This paper examines the existing literature demonstrating favorable outcomes associated with antioxidant supplementation.

Dietary antioxidants and hypertension among menopausal women in Rafsanjan Cohort Study

Studies on the beneficial role of dietary antioxidants in preventing or managing hypertension in postmenopausal women are infrequent. The present cross-sectional study aimed to assess the association between dietary antioxidants and hypertension among menopausal women in Rafsanjan, a city located in the southeast of Iran. This study was based on data from the Rafsanjan Cohort Study (RCS), as part of the Prospective Epidemiological Research Studies in IrAN (PERSIAN). Among 2359 postmenopausal women, finally, 1936 women were included in this study. Participants were grouped as having normal blood pressure (BP), elevated BP, stage 1 hypertension, or stage 2 hypertension as defined by the 2017 American College of Cardiology (ACC)/American Heart Association (AHA) BP guideline. A food frequency questionnaire (FFQ), was utilized to ascertain the levels of various nutrients and dietary antioxidants in the diet. The association between dietary intakes of antioxidants and blood pressure groups was evaluated by crude and adjusted models in the multinominal logistics regression analysis. Normal BP, elevated BP, stage 1 hypertension, and stage 2 hypertension were observed in 35.69%, 3.62%, 10.59%, and 50.10% of postmenopausal women respectively. In the adjusted model, in subjects with higher consumption of β-carotene, the odds ratios of elevated BP in the 3rd quartile was about 2 times (OR: 2.04 (1.06-3.93) higher than 1st quartile. Also, in subjects with medium quality of DAQS, the odds ratios of elevated BP and stage 1 blood pressure were about 2 times (OR: 2.09 (1.05-4.17) and 1.69 times (OR: 1.69 (1.09-2.63) higher than subjects with low quality respectively. Furthermore, we did not find any statistically significant association between increased intake of dietary antioxidants and decreased odds of hypertension. After controlling the effects of confounding variables, increased dietary intake of selenium, carotenoids, vitamin A, vitamin C, and vitamin E did not decrease the odds of hypertension in postmenopausal women. Accordingly, it is suggested that this association be further investigated in the follow-up phase of this prospective study.

Dietary Total Antioxidant Capacity, a Diet Quality Index Predicting Mortality Risk in US Adults: Evidence from the NIH-AARP Diet and Health Study

Dietary total antioxidant capacity (TAC) is an index representing the total antioxidant power of antioxidants consumed via the diet. This study aimed to investigate the association between dietary TAC and mortality risk in the US adults using data from the NIH-AARP Diet and Health Study. A total of 468,733 adults aged 50-71 years were included. Dietary intake was assessed using a food frequency questionnaire. Dietary TAC from diet was calculated from antioxidants including vitamin C, vitamin E, carotenoids, and flavonoids, and TAC from dietary supplements was calculated from supplemental vitamin C, vitamin E, and beta-carotene. During a median follow-up of 23.1 years, 241,472 deaths were recorded. Dietary TAC was inversely associated with all-cause (hazard ratio (HR) for quintile 5 vs. quintile 1: 0.97, 95% confidence interval (CI): 0.96-0.99, p for trend < 0.0001) and cancer mortality (HR for quintile 5 vs. quintile 1: 0.93, 95% CI: 0.90-0.95, p for trend < 0.0001). However, dietary supplement TAC was inversely associated with cancer mortality risk only. These findings indicate that consuming a habitual diet high in antioxidants may reduce the risk of all-cause and cancer mortality and TAC from foods might confer greater health benefits than TAC from dietary supplements.

Oxidative Stress, Antioxidants and Hypertension

As a major cause of morbidity and mortality globally, hypertension remains a serious threat to global public health. Despite the availability of many antihypertensive medications, several hypertensive individuals are resistant to standard treatments, and are unable to control their blood pressure. Regulation of the renin-angiotensin-aldosterone system (RAAS) controlling blood pressure, activation of the immune system triggering inflammation and production of reactive oxygen species, leading to oxidative stress and redox-sensitive signaling, have been implicated in the pathogenesis of hypertension. Thus, besides standard antihypertensive medications, which lower arterial pressure, antioxidant medications were tested to improve antihypertensive treatment. We review and discuss the role of oxidative stress in the pathophysiology of hypertension and the potential use of antioxidants in the management of hypertension and its associated organ damage.

Association between oxidative balance score and new-onset hypertension in adults: A community-based prospective cohort study

Introduction

Oxidative stress plays a key role in the pathophysiology of hypertension development. The oxidative balance score (OBS) comprises dietary and lifestyle pro- and anti-oxidant components and reflects the overall oxidative stress burden. We aimed to evaluate the association between the OBS and new-onset hypertension (HTN) using large, community-based, prospective Korean cohort data.

Methods

Among 10,030 participants aged 40-69 years included in the Korean Genome and Epidemiology Study, the data of 5,181 participants were analyzed. The hazard ratio (HR) and 95% confidence interval (CI) for new-onset HTN according to sex-specific OBS quartile groups were calculated using univariable and multivariable Cox proportional hazard regression analyses.

Results

During the mean 13.6-year follow-up period, 1,157 men and 1,196 women developed new-onset HTN. Compared to the Q1 group, the adjusted HRs (95%CI) for new-onset HTN in the Q2, Q3, and Q4 groups were 0.96 (0.82-1.16), 0.85 (0.72-0.99), and 0.71 (0.59-0.86) in men and 0.81 (0.69-0.95), 0.81(0.68-0.95), and 0.70 (0.57-0.84) in women, respectively.

Discussion

Individuals with high OBS are at lower risk of developing HTN. This study suggests that a healthy lifestyle and antioxidant rich diet could be a preventive strategy for HTN.

Association between dietary total antioxidant capacity and hypertension in Iranian Kurdish women

Background

Antioxidants intake from diet has been identified as one of the effective factors in the development of hypertension (HTN). The present study aimed to investigate the association between total antioxidant capacity (TAC) and HTN in women.

Methods

This cross-sectional study was performed using the baseline phase data of the ravansar non-communicable disease cohort study. The TAC was calculated using food items of the food frequency questionnaire. TAC scores were classified into four groups (quartile). The first and fourth quartiles had the lowest and highest TAC scores, respectively. Logistic regression analysis was utilized to estimate the odds ratio.

Results

A total of 5067 women were included in the study. Women with the highest socioeconomic status (SES) had a significantly higher TAC intake compared to those with the lowest SES (P < 0.001). The participants in the third and fourth quartiles of the TAC had significantly lower odds of HTN, respectively by 21% (OR = 0.79; 95% CI: 0.64, 0.972) and 26% (OR = 0.74; 95% CI: 0.60, 0.91), compared to the first quartile. After adjusting for confounding variables was found to significantly reduce the odds of developing HTN in the fourth quartile of TAC by 22% compared to the first quartile (OR = 0.78; 95% CI: 0.62, 0.97).

Conclusion

A high dietary TAC was associated to a decreased odd of HTN in women. We could suggest a diet rich in natural antioxidants as it may help prevent development of HTN.

Antioxidant Properties of Alpha-Lipoic (Thioctic) Acid Treatment on Renal and Heart Parenchyma in a Rat Model of Hypertension

Renal and cardiac impairments are frequent events in the presence of hypertension. Organ damage is mainly linked to oxidative stress due to high blood pressure and may be reduced by antioxidant supplementation. Alpha-lipoic acid (ALA) is one of most effective antioxidants. It is widely used as a nutritional supplement in a racemic mixture (+/–), even though the (+)-enantiomer is biologically active. This study was designed to investigate the effect of treatment with (+/–)-ALA and its enantiomers on renal and heart parenchyma in spontaneously hypertensive rats (SHR), using immunochemical and immunohistochemical techniques. The results confirmed that the oxidative mechanisms of organ alterations, due to hypertension, and characterized by glomerular and tubular lesions, left ventricular hypertrophy, and fibrosis but not by apoptosis were accompanied by proteins’ and nucleic acids’ oxidation. We found greater effectiveness of (+)-ALA compared to (+/−)-ALA in reducing oxidative stress, cardiac and renal damages in SHR. To conclude, these data propose (+)-ALA as one of the more appropriate antioxidant molecules to prevent renal and cardiac alterations associated with hypertension.

Inverse association between dietary vitamin A intake and new-onset hypertension

BACKGROUND & AIMS

The prospective relation of dietary vitamin A intake with hypertension remains uncertain. We aimed to investigate the relationship of dietary vitamin A intake with new-onset hypertension and examine possible effect modifiers in general population.

METHODS

This prospective cohort study included 12,245 participants who were free of hypertension at baseline from China Health and Nutrition Survey (CHNS). Dietary intake was measured by 3 consecutive 24-h dietary recalls combined with a household food inventory. The study outcome was new-onset hypertension, defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg or diagnosed by physician or under antihypertensive treatment during the follow-up.

RESULTS

During a median follow-up duration of 6.1 years, a total of 4,304 (35.1%) participants developed new-onset hypertension. Overall, there was an L-shaped relation of total dietary vitamin A intake with new-onset hypertension (P for nonlinearity <0.001). Accordingly, compared with participants with lower vitamin A intake (quartile 1, <227.3 μg RE/day), those with higher vitamin A intake (quartile 2-4, ≥227.3 μg RE/day) had a significantly lower risk of new-onset hypertension (adjusted HR, 0.73; 95%CI: 0.63, 0.78). Similar results were found for plant-derived vitamin A intake (adjusted HR, 0.65; 95% CI, 0.61, 0.70) or animal-derived vitamin A intake (adjusted HR, 0.76; 95% CI, 0.70, 0.82).

CONCLUSIONS

There was a L-shaped relation of dietary vitamin A intake with new-onset hypertension in general Chinese adults. Our results emphasized the importance of maintaining relatively higher vitamin A intake levels for the prevention of hypertension.

Nitric oxide and oxidative stress pathways do not contribute to sex differences in renal injury and function in Dahl SS/Jr rats

The burden of hypertension in the United States is increasing and yields significant morbidity and mortality, and sex differences in hypertension are widely recognized. Reduced nitric oxide (NO) bioavailability and increased oxidative stress are known to contribute to the pathogenesis of hypertensive renal injury, and but their contributions to sex differences in injury progression of are undefined. Our purpose was to test the hypothesis that male hypertensive rats have accelerated renal injury compared to females and to determine the contributions of the nitric oxide pathway and oxidative stress in these differences. Male and female Dahl SS/Jr rats, a model that spontaneously develops hypertension with age, were allowed to age on a 0.3% NaCl diet until 3 or 6 months of age, at which points blood pressure was measured and plasma, tissue, and urine were collected. While no significant sex differences in blood pressure were present at either time point, renal injury measured by urine protein excretion was more severe (male = 44.9 ± 6; female = 15±3 mg/day/100 g bw, p = .0001), and renal function was reduced (male = 0.48 ± 0.02; female = 0.7 ± 0.03 ml min-1  g-1 kw, p = .001) in males compared to females with age. Both male and female rats exhibited reduced nitric oxide metabolites (3 months: male = 0.65 ± 0.1; female = 0.74 ± 0.3; 6 months: male = 0.16 ± 0.1; female = 0.41 ± 0.1 ml min-1  g-1 kw, p, age = 0.02, p, sex = 0.3). Levels of urinary TBARS were similar (3 months: male = 20±1.5; female = 23±1.8; 6 months: male = 26±4.8; female = 23±4.7µM day g-1 kw, p, age = 0.4, p, sex = 0.9), extracellular superoxide dismutase (EC SOD) mRNA was greater in females (3 months: male = 0.35 ± 0.03; female = 1.4 ± 0.2; 6 months: male = 0.4 ± 0.05; female = 1.3 ± 0.1 normalized counts, p, age = 0.7, p, sex < 0.0001), but EC SOD protein expression was not different (3 months: male = 0.01 ± 0.002; female = 0.01 ± 0.002; 6 months: male = 0.02 ± 0.004; female = 0.01 ± 0.002 relative density, p, age = 0.2, p, sex = 0.8). These data support the presence of significant sex differences in renal injury and function in the Dahl S rat and identify a need for further study into the mechanisms involved.

Genetic polymorphisms associated with reactive oxygen species and blood pressure regulation

Hypertension is the most prevalent cause of cardiovascular disease and kidney failure, but only about 50% of patients achieve adequate blood pressure control, in part, due to inter-individual genetic variations in the response to antihypertensive medication. Significant strides have been made toward the understanding of the role of reactive oxygen species (ROS) in the regulation of the cardiovascular system. However, the role of ROS in human hypertension is still unclear. Polymorphisms of some genes involved in the regulation of ROS production are associated with hypertension, suggesting their potential influence on blood pressure control and response to antihypertensive medication. This review provides an update on the genes associated with the regulation of ROS production in hypertension and discusses the controversies on the use of antioxidants in the treatment of hypertension, including the antioxidant effects of antihypertensive drugs.

High dietary total antioxidant capacity is associated with a reduced risk of hypertension in French women

Background

Although there is evidence for a reduced risk of hypertension associated with fruit and vegetable consumption, the relationship between the total antioxidant capacity of the diet (TAC) and the risk of hypertension has not been previously examined. We aimed to evaluate that association in the large E3N French prospective cohort of women.

Methods

Dietary TAC was estimated using total radical-trapping ability parameter (TRAP) assay food values; self-reported incident hypertension cases were validated. Cox regression models were adjusted for conventional risk factors, body mass index, physical activity, energy, sodium, magnesium, omega-3 fatty acids, and alcohol.

Results

After an average 12.7 years of follow up, there were 9350 incident cases of hypertension among 40,576 women. Dietary TAC was inversely associated with the risk of hypertension with a 15% lower risk of hypertension in those in the fifth vs. first quintile (HR_Q5 0.85 [CI 95% 0.74; 0.95] p-trend 0.03) An inverse dose-effect relationship was observed for dietary TAC excluding coffee (HR_Q5 0.85 [CI 95% 0.74; 0.95], p-trend 0.0008), while for dietary TAC from coffee, only the highest quintile was inversely associated with risk (HR_Q5 0.86 [0.75, 0.97], p-trend 0.20). In a fully partitioned model with major dietary TAC contributors, TAC from fruit/vegetables, wine, and miscellaneous sources was inversely associated with risk, while associations with TAC from coffee, tea, and chocolate were not statistically significant.

Conclusions

In a large prospective cohort, the risk of incident hypertension in women was inversely associated with the antioxidant capacity of the diet, suggesting that promoting a diet naturally rich in antioxidants might help prevent the development of hypertension.

Electronic supplementary material

The online version of this article (10.1186/s12937-019-0456-0) contains supplementary material, which is available to authorized users.

Role of Zinc and Selenium in Oxidative Stress and Immunosenescence: Implications for Healthy Aging and Longevity

Aging is a complex process that includes gradual and spontaneous biochemical and physiological changes which contributes to a decline in performance and increased susceptibility to diseases. Zn and Se are essential trace elements that play a pivotal role in immune functions and antioxidant defense and, consequently, are claimed to play also a role in successful aging trajectories. Consistently with their nature of essential trace elements, a plethora of data obtained “in vitro” and “in vivo” (in humans and animal models) support the relevance of Zn and Se for both the innate and adoptive immune response. Moreover, Zn and Se are strictly involved in the synthesis and regulation of activity of proteins and enzymes, e.g., metallothioneins (MT) and glutathione peroxidase (GPX), that are necessary for our endogenous antioxidant response. This is clearly important to protect our cells from oxidative damage and to slow the decline of our immune system with aging. Age-related changes affecting tissue levels of Zn and Se may indicate that the risk of Zn and Se deficiency increases with aging. However, it is still unclear which of these changes can be the consequence of a “real deficiency” and which can be part of our physiological compensatory response to the accumulating damage occurring in aging. Furthermore, the upregulation of antioxidant proteins (Zn and Se dependent) may be a manifestation of self-induced oxidative stress. By the way, Zn and Se dependent proteins are modulated not only by nutritional status, but also by well-known hallmarks of aging that play antagonistic functions, such as the deregulated nutrient sensing pathways and cellular senescence. Thus, it is not an easy task to conduct Zn or Se supplementation in elderly and it is emerging consistent that these kind of supplementation requires an individualized approach. Anyway, there is consistent support that supplementation with Zn using doses around 10 mg/day is generally safe in elderly and may even improve part of immune performances in those subjects with a baseline deficiency. Regarding Se supplementation, it may induce both beneficial and detrimental effects on cellular immunity depending on the form of Se, supplemental dose, and delivery matrix. The nutritional association of supplements based on “Zn plus Se” is hypothesized to provide additional benefits, but this will likely need a more complex individualized approach. The improvement of our knowledge around screening and detection of Zn and Se deficiency in aging could lead to substantial benefits in terms of efficacy of nutritional supplements aimed at ameliorate performance and health in aging.

Effects of Multivitamin and Multimineral Supplementation on Blood Pressure: A Meta-Analysis of 12 Randomized Controlled Trials

Previous studies have not drawn a consistent conclusion about effect of multivitamin and multimineral supplementation (MVMS) on blood pressure. A comprehensive search of PubMed, Embase and Cochrane Library (up to May 2018) and references of relevant articles was undertaken. The present meta-analysis included 12 randomized controlled trials (RCTs), of which eight RCTs in 2011 subjects evaluated the effect of MVMS on blood pressure and four RCTs in 21,196 subjects evaluated the effect of MVMS on the risk of hypertension. MVMS had a lowering effect on systolic blood pressure (SBP) and diastolic blood pressure (DBP): the weighted mean difference (WMD) was -1.31 mmHg (95% CI, -2.48 to -0.14 mmHg) and -0.71 mmHg (95% CI, -1.43 to 0.00 mmHg), respectively. Subgroup analysis indicated that the lowering effect of MVMS on blood pressure was only significant in 134 subjects with chronic disease but not in 1580 healthy subjects, and the WMD for systolic blood pressure (SBP) and DBP in subjects with chronic disease was -6.29 mmHg (95% CI, -11.09 to -1.50 mmHg) and -2.32 mmHg (95% CI, -4.50 to -0.13 mmHg), respectively. The effect size of MVMS on SBP in 58 hypertensive subjects (WMD, -7.98 mmHg; 95% CI, -14.95 to -1.02 mmHg) was more than six times of that in 1656 normotensive subjects (WMD, -1.25 mmHg; 95% CI, -2.48 to -0.02 mmHg). However, no significant effect on DBP was observed in both hypertensive and normotensive subgroups. There was no significant effect of MVMS on risk of hypertension in 22,852 subjects with a normal blood pressure at baseline. In conclusion, although MVMS had a significant lowering effect on blood pressure in normotensive subjects, the lowering effect was too small to effectively prevent future hypertension. MVMS may be an effective method for blood pressure control in subjects with chronic disease including hypertension, but the sample size of subjects with hypertension or other chronic disease was too small, and more well-designed RCTs are needed to confirm this result.

Evaluation of the level of dynamic thiol/disulphide homeostasis in adolescent patients with newly diagnosed primary hypertension

BACKGROUND

Thiol/disulphide homeostasis plays a critical role in numerous intracellular enzymatic pathways including antioxidant defense and detoxification. This study was designed to investigate the impact of thiol/disulfide homeostasis in adolescent patients with recently diagnosed primary hypertension (HT) using a novel and automated method.

METHODS

Native thiol/disulphide levels were measured by a novel spectrophotometric method (Cobasc 501, Roche Diagnostics, Mannheim, Germany) in 30 patients with primary HT together with 30 healthy controls.

RESULTS

The levels of native thiol, total thiol, and native thiol/total thiol ratios were significantly lower, while the disulphide level, disulphide/native thiol, and disulphide/total thiol ratios were significantly higher in patients with primary HT compared with the control group. There were significant positive correlations between 24-h mean systolic and diastolic blood pressure and disulphide levels, disulphide/native thiol, and disulphide/total thiol ratios. A multiple linear regression model showed that a disulphide/native thiol ratio above 5 and family history of HT are independent predictors of HT.

CONCLUSIONS

Our study showed that dynamic thiol/disulphide homeostasis shifted towards disulphide formation in adolescent patients with primary HT. Understanding the role of thiol/disulfide homeostasis in primary HT might provide new therapeutic intervention strategies for patients.

The Future Challenge of Reactive Oxygen Species (ROS) in Hypertension: From Bench to Bed Side

Reactive oxygen species (ROS) act as signaling molecules that control physiological processes, including cell adaptation to stress. Redox signaling via ROS has quite recently become the focus of much attention in numerous pathological contexts, including neurodegenerative diseases, kidney and cardiovascular disease. Imbalance in ROS formation and degradation has also been implicated in essential hypertension. Essential hypertension is characterized by multiple genetic and environmental factors which do not completely explain its associated risk factors. Thereby, even if advances in therapy have led to a significant reduction in hypertension-associated complications, to interfere with the unbalance of redox signals might represent an additional therapeutic challenge. The decrease of nitric oxide (NO) levels, the antioxidant activity commonly found in preclinical models of hypertension and the ability of antioxidant approaches to reduce ROS levels have spurred clinicians to investigate the contribution of ROS in humans. Indeed, particular effort has recently been devoted to understanding how redox signaling may contribute to vascular pathobiology in human hypertension. However, although biomarkers of oxidative stress have been found to positively correlate with blood pressure in preclinical model of hypertension, human data are less convincing. We herein provide an overview of the most relevant mechanisms via which oxidative stress might contribute to the pathophysiology of essential hypertension. Moreover, alternative approaches, which are directed towards improving antioxidant machinery and/or interfering with ROS production, are also discussed.

Oxidative Stress and Hypertensive Diseases

It has become clear that reactive oxygen species (ROS) contribute to the development of hypertension via myriad effects. ROS are essential for normal cell function; however, they mediate pathologic changes in the brain, the kidney, and blood vessels that contribute to the genesis of chronic hypertension. There is also emerging evidence that ROS contribute to immune activation in hypertension. This article discusses these events and how they coordinate to contribute to hypertension and its consequent end-organ damage.

Mitohormesis in exercise training

Hormesis is a process whereby exposure to a low dose of a potentially harmful stressor promotes adaptive changes to the cell that enables it to better tolerate subsequent stress. In recent years this concept has been applied specifically to the mitochondria (mitohormesis), suggesting that in response to a perturbation the mitochondria can initiate and transduce a signal to the nucleus that coordinates a transcriptional response resulting in both mitochondrial and non-mitochondrial adaptations that return and maintain cellular homeostasis. In this review we summarize the evidence that mitohormesis is a significant adaptive-response signaling pathway, and suggest that it plays a role in mediating exercise-induced adaptations. We discuss potential mitochondrial emitters of retrograde signals that may activate known exercise-sensitive transcription factors to modulate transcription responses to exercise, and draw on evidence from mitochondrial dysfunction animal models to support a role for mitohormesis in mitochondrial biogenesis. Studies directly linking mitohormesis to the exercise training response are lacking, however mounting evidence suggests numerous signals are emitted from the mitochondria during exercise and have the potential to induce a nuclear transcription response, with reactive oxygen species (ROS) being the primary candidate.

Multivitamin use and the risk of hypertension in a prospective cohort study of women

OBJECTIVE

Despite the widespread use of multivitamin supplements, little is known regarding their effects on blood pressure (BP) and the development of hypertension. We, therefore, sought to prospectively investigate how multivitamin use was associated with incident hypertension among middle-aged and older women.

METHODS

We studied 28 157 women from the Women's Health Study aged at least 45 years and free of cardiovascular disease, cancer, and hypertension at baseline. Women reported information on a wide range of lifestyle, clinical, and dietary factors, including multivitamin and other supplement use at baseline. Hypertension was identified on baseline and annual follow-up questionnaires. Incident hypertension was defined as either a new diagnosis of hypertension by a physician, initiation of antihypertensive medication, newly reported SBP at least 140 mmHg, or DBP at least 90 mmHg during follow-up.

RESULTS

During a mean follow-up of 11.5 years, we identified 16 316 cases of incident hypertension. We found that neither baseline (hazard ratio = 1.03, 95% confidence interval: 1.00, 1.07) nor time-varying multivitamin use (hazard ratio = 0.97, 95% confidence interval: 0.94-1.00) were associated with the risk of incident hypertension in multivariable-adjusted models. When we investigated the duration of multivitamin use reported at baseline, we also observed no association with the risk of hypertension.

CONCLUSION

The results from this prospective study of middle-aged and older women suggest that neither baseline multivitamin use nor time-varying multivitamin use is associated with the risk of developing hypertension.

Immune activation caused by vascular oxidation promotes fibrosis and hypertension

Vascular oxidative injury accompanies many common conditions associated with hypertension. In the present study, we employed mouse models with excessive vascular production of ROS (tg(sm/p22phox) mice, which overexpress the NADPH oxidase subunit p22(phox) in smooth muscle, and mice with vascular-specific deletion of extracellular SOD) and have shown that these animals develop vascular collagen deposition, aortic stiffening, renal dysfunction, and hypertension with age. T cells from tg(sm/p22phox) mice produced high levels of IL-17A and IFN-γ. Crossing tg(sm/p22phox) mice with lymphocyte-deficient Rag1(-/-) mice eliminated vascular inflammation, aortic stiffening, renal dysfunction, and hypertension; however, adoptive transfer of T cells restored these processes. Isoketal-protein adducts, which are immunogenic, were increased in aortas, DCs, and macrophages of tg(sm/p22phox) mice. Autologous pulsing with tg(sm/p22phox) aortic homogenates promoted DCs of tg(sm/p22phox) mice to stimulate T cell proliferation and production of IFN-γ, IL-17A, and TNF-α. Treatment with the superoxide scavenger tempol or the isoketal scavenger 2-hydroxybenzylamine (2-HOBA) normalized blood pressure; prevented vascular inflammation, aortic stiffening, and hypertension; and prevented DC and T cell activation. Moreover, in human aortas, the aortic content of isoketal adducts correlated with fibrosis and inflammation severity. Together, these results define a pathway linking vascular oxidant stress to immune activation and aortic stiffening and provide insight into the systemic inflammation encountered in common vascular diseases.

High serum carotenoids associated with lower risk for the metabolic syndrome and its components among Japanese subjects: Mikkabi cohort study

Recent epidemiological studies show the association of carotenoids with the metabolic syndrome (MetS), but thorough longitudinal cohort studies regarding this association have not been well conducted. The objective of this study was to investigate longitudinally whether serum carotenoids are associated with the risk of developing the MetS and its components in Japanese subjects. We conducted a follow-up study on 1073 men and women aged 30-79 years at the baseline from the Mikkabi prospective cohort study. Those who participated in the baseline and completed follow-up surveys were examined longitudinally. Over the 10-year period, 910 subjects (295 men and 615 women) took part in the follow-up survey at least once. Over a mean follow-up period of 7·8 (sd 2·9) years, thirty-six men and thirty-one women developed new MetS. After adjustments for confounders, the hazard ratio (HR) for the MetS in the highest tertile of serum β-carotene against the lowest tertile was 0·47 (95 % CI 0·23, 0·95). On the other hand, significantly lower risks for dyslipidaemia were observed in the highest tertiles of serum α- and β-carotene and β-cryptoxanthin (HR 0·66; 95 % CI 0·46, 0·96; HR, 0·54; 95 % CI 0·37, 0·79; and HR 0·66; 95 % CI 0·44, 0·99, respectively). Other significant associations between the risks for obesity, high blood pressure and hyperglycaemia with serum carotenoids were not observed. Our results further support the hypothesis that eating a diet rich in carotenoids might help prevent the development of the MetS and its complications in Japanese subjects.

Mitohormesis: Promoting Health and Lifespan by Increased Levels of Reactive Oxygen Species (ROS)

Increasing evidence indicates that reactive oxygen species (ROS), consisting of superoxide, hydrogen peroxide, and multiple others, do not only cause oxidative stress, but rather may function as signaling molecules that promote health by preventing or delaying a number of chronic diseases, and ultimately extend lifespan. While high levels of ROS are generally accepted to cause cellular damage and to promote aging, low levels of these may rather improve systemic defense mechanisms by inducing an adaptive response. This concept has been named mitochondrial hormesis or mitohormesis. We here evaluate and summarize more than 500 publications from current literature regarding such ROS-mediated low-dose signaling events, including calorie restriction, hypoxia, temperature stress, and physical activity, as well as signaling events downstream of insulin/IGF-1 receptors, AMP-dependent kinase (AMPK), target-of-rapamycin (TOR), and lastly sirtuins to culminate in control of proteostasis, unfolded protein response (UPR), stem cell maintenance and stress resistance. Additionally, consequences of interfering with such ROS signals by pharmacological or natural compounds are being discussed, concluding that particularly antioxidants are useless or even harmful.

Micronutrient-gene interactions related to inflammatory/immune response and antioxidant activity in ageing and inflammation. A systematic review

Recent longitudinal studies in dietary daily intake in human centenarians have shown that a satisfactory content of some micronutrients within the cells maintain several immune functions, a low grade of inflammation and preserve antioxidant activity. Micronutrients (zinc, copper, selenium) play a pivotal role in maintaining and reinforcing the performances of the immune and antioxidant systems as well as in affecting the complex network of the genes (nutrigenomic) with anti- and pro-inflammatory tasks. Genes of pro- and anti-inflammatory cytokines and some key regulators of trace elements homeostasis, such as Metallothioneins (MT), are involved in the susceptibility to major geriatric disease/disorders. Moreover, the genetic inter-individual variability may affect the nutrients' absorption (nutrigenetic) with altered effects on inflammatory/immune response and antioxidant activity. The interaction between genetic factors and micronutrients (nutrigenomic and nutrigenetic approaches) may influence ageing and longevity because the micronutrients may become also toxic. This review reports the micronutrient-gene interactions in ageing and their impact on the healthy state with a focus on the method of protein-metal speciation analysis. The association between micronutrient-gene interactions and the protein-metal speciation analysis can give a complete picture for a personalized nutrient supplementation or chelation in order to reach healthy ageing and longevity.

Role of mitochondrial oxidative stress in hypertension

Based on mosaic theory, hypertension is a multifactorial disorder that develops because of genetic, environmental, anatomical, adaptive neural, endocrine, humoral, and hemodynamic factors. It has been recently proposed that oxidative stress may contribute to all of these factors and production of reactive oxygen species (ROS) play an important role in the development of hypertension. Previous studies focusing on the role of vascular NADPH oxidases provided strong support of this concept. Although mitochondria represent one of the most significant sources of cellular ROS generation, the regulation of mitochondrial ROS generation in the cardiovascular system and its pathophysiological role in hypertension are much less understood. In this review, the role of mitochondrial oxidative stress in the pathophysiology of hypertension and cross talk between angiotensin II signaling, pathways involved in mechanotransduction, NADPH oxidases, and mitochondria-derived ROS are considered. The possible benefits of therapeutic strategies that have the potential to attenuate mitochondrial oxidative stress for the prevention/treatment of hypertension are also discussed.

Oxidative stress and hypertension

Mammalian cells are capable of generating metabolites of oxygen, referred to as reactive oxygen species (ROS) via the action of several enzymes. In vascular cells, ROS are predominantly produced by the NADPH oxidases, uncoupled nitric oxide synthase, xanthine oxidase and by mitochondrial sources. In hypertension, ROS production by these sources is increased, and this not only contributes to hypertension, but also causes vascular disease and dysfunction. ROS production in other organs, particularly the kidney and the centers within the brain, likely participate in blood pressure regulation. Despite the wealth of data supporting a role of ROS in hypertension and other cardiovascular diseases, treatment with commonly employed antioxidants have failed, and in some cases have proven harmful, prompting a reconsideration of the concept of oxidative stress. Within the cell, ROS are produced locally and have important signaling roles, such that scavenging of these species by exogenous antioxidants is difficult and could produce untoward effects. In this article, we consider these tissues and discuss potential new approaches to treatment of "oxidative stress".

Extending life span by increasing oxidative stress

Various nutritional, behavioral, and pharmacological interventions have been previously shown to extend life span in diverse model organisms, including Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, mice, and rats, as well as possibly monkeys and humans. This review aims to summarize published evidence that several longevity-promoting interventions may converge by causing an activation of mitochondrial oxygen consumption to promote increased formation of reactive oxygen species (ROS). These serve as molecular signals to exert downstream effects to ultimately induce endogenous defense mechanisms culminating in increased stress resistance and longevity, an adaptive response more specifically named mitochondrial hormesis or mitohormesis. Consistently, we here summarize findings that antioxidant supplements that prevent these ROS signals interfere with the health-promoting and life-span-extending capabilities of calorie restriction and physical exercise. Taken together and consistent with ample published evidence, the findings summarized here question Harman's Free Radical Theory of Aging and rather suggest that ROS act as essential signaling molecules to promote metabolic health and longevity.

Angiotensin-II-induced reactive oxygen species along the SFO-PVN-RVLM pathway: implications in neurogenic hypertension

Neurogenic hypertension has been the subject of extensive research worldwide. This review is based on the premise that some forms of neurogenic hypertension are caused in part by the formation of angiotensin-II (Ang-II)-induced reactive oxygen species along the subfornical organ-paraventricular nucleus of the hypothalamus-rostral ventrolateral medulla pathway (SFO-PVN-RVLM pathway). We will discuss the recent contribution of our laboratory and others regarding the mechanisms by which neurons in the SFO (an important circumventricular organ) are activated by Ang-II, how the SFO communicates with two other important areas involved in sympathetic activity regulation (PVN and RVLM) and how Ang-II-induced reactive oxygen species participate along the SFO-PVN-RVLM pathway in the pathogenesis of neurogenic hypertension.

Dietary patterns and blood pressure among middle-aged and elderly Chinese men in Shanghai

The prevalence of hypertension has increased over the past decade in many developed and developing countries, including China. This increase may be associated with changes in lifestyle, including dietary patterns. We evaluated the association of dietary patterns with blood pressure (BP) by using data from a large, population-based cohort study of middle-aged and elderly Chinese men, the Shanghai Men's Health Study. The present cross-sectional analysis includes 39 252 men who reported no prior history of hypertension, diabetes, CHD, or stroke nor use of antihypertensive drugs at study enrolment. Three dietary patterns, 'vegetable', 'fruit and milk' and 'meat', were derived using factor analysis. The fruit and milk diet was inversely associated with both systolic and diastolic BP (Ptrend < 0.001). The adjusted mean systolic BP was 2.9 mmHg lower (95 % CI - 3.4, - 2.4), and diastolic BP was 1.7 mmHg lower (95 % CI - 2.0, - 1.4) for men in the highest quintile of the 'fruit and milk' pattern compared with men in the lowest quintile. This inverse association was more evident among heavy drinkers; the highest quintile of the 'fruit and milk' pattern was associated with a 4.1 mmHg reduction in systolic BP v. a 2.0 mmHg reduction among non-drinkers (Pinteraction = 0.003) compared to the lowest quintile. The corresponding reductions in diastolic BP were 2.0 v. 1.3 mmHg (Pinteraction = 0.011). The 'fruit and milk' pattern was associated with a lower prevalence of both pre-hypertension and hypertension, and the associations appeared to be stronger among drinkers. Results of the present study suggest an important role for diet in the prevention of hypertension.

How increased oxidative stress promotes longevity and metabolic health: The concept of mitochondrial hormesis (mitohormesis)

Recent evidence suggests that calorie restriction and specifically reduced glucose metabolism induces mitochondrial metabolism to extend life span in various model organisms, including Saccharomyces cerevisiae, Drosophila melanogaster, Caenorhabditis elegans and possibly mice. In conflict with Harman's free radical theory of aging (FRTA), these effects may be due to increased formation of reactive oxygen species (ROS) within the mitochondria causing an adaptive response that culminates in subsequently increased stress resistance assumed to ultimately cause a long-term reduction of oxidative stress. This type of retrograde response has been named mitochondrial hormesis or mitohormesis, and may in addition be applicable to the health-promoting effects of physical exercise in humans and, hypothetically, impaired insulin/IGF-1-signaling in model organisms. Consistently, abrogation of this mitochondrial ROS signal by antioxidants impairs the lifespan-extending and health-promoting capabilities of glucose restriction and physical exercise, respectively. In summary, the findings discussed in this review indicate that ROS are essential signaling molecules which are required to promote health and longevity. Hence, the concept of mitohormesis provides a common mechanistic denominator for the physiological effects of physical exercise, reduced calorie uptake, glucose restriction, and possibly beyond.

Losartan improved respiratory function and coenzyme Q content in brain mitochondria of young spontaneously hypertensive rats

Increased production of free radicals and impairment of mitochondrial function are important factors in the pathogenesis of hypertension. This study examined the impact of hypertension on mitochondrial respiratory chain function, coenzyme Q(9) (CoQ(9)), coenzyme Q(10) (CoQ(10)), and alpha-tocopherol content in brain mitochondria, and the effect of blockade of angiotensin II type 1 receptors (AT1R) in the prehypertensive period on these parameters. In addition, blood pressure, heart and brain weight to body weight ratios, and the geometry of the basilar artery supplying the brain were evaluated. In the 9th week blood pressure and heart weight/body weight ratio were significantly increased and brain weight/body weight ratio was significantly decreased in spontaneously hypertensive rats (SHR) when compared to Wistar rats (WR). The cross-sectional area of the basilar artery was increased in SHR. Glutamate-supported respiration, the rate of ATP production, and concentrations of CoQ(9), CoQ(10), and alpha-tocopherol were decreased in SHR. The succinate-supported function and cytochrome oxidase activity were not changed. The treatment of SHR with losartan (20 mg/kg/day) from 4th to 9th week of age exerted preventive effect against hypertension, heart and arterial wall hypertrophy, and brain weight/body weight decline. After the therapy, the rate of ATP production and the concentration of CoQ increased in comparison to untreated SHR. The impairment of energy production and decreased level of lipid-soluble antioxidants in brain mitochondria as well as structural alterations in the basilar artery may contribute to increased vulnerability of brain tissue in hypertension. Long-term treatment with AT1R blockers may prevent brain dysfunction in hypertension.

Refractory blood pressure in female SHR to increased oxidative stress is not mediated by NO or by upregulation of renal antioxidant enzymes

There is a sex difference in the blood pressure (BP) responses to prooxidants and antioxidants in the spontaneously hypertensive rat (SHR). In contrast to males, BP in female SHR does not decrease in response to antioxidants, such as tempol or apocynin, or increase in response to the prooxidant, molsidomine. Molsidomine decreases BP and increases expression of antioxidants in male Wistar-Kyoto rats (WKY), but not male SHR. The present study tested the hypothesis that the mechanism responsible for the lack of a pressor response to molsidomine in females is due to higher endogenous nitric oxide (NO) or to compensatory upregulation of renal antioxidant enzymes. Female SHR were treated with molsidomine in the presence or absence of nitro-L-arginine methyl ester (L-NAME) for 2 wk. Molsidomine increased nitrate/nitrite (NO(x)) and F2-isoprostane (F2-IsoP) excretion, whereas L-NAME reduced NO(x) but increased F-Isop. Molsidomine and L-NAME together further reduced NO(x) and increased F2-IsoP. Molsidomine alone had no effect on BP; L-NAME alone increased BP. The combination of molsidomine and L-NAME did not increase BP above L-NAME alone levels. Whole body and renal oxidative stress increased, while renal cortical Cu,Zn-SOD expression was downregulated and catalase was upregulated by molsidomine; glutathione peroxidase expression was unaffected. These data support our previous studies suggesting that BP in female SHR is independent of either increases or decreases in oxidative stress. The mechanisms responsible for the sex difference in BP response to increase or decrease of oxidative stress are not due to increased NO in females or to compensatory upregulation of antioxidant enzymes in response to increases in oxidants.

Chronic antioxidant therapy fails to ameliorate hypertension: potential mechanisms behind

Hypertension in association with oxidative stress belongs to the most discussed topics within the literature on cardiovascular diseases. It is generally believed that elevated production of reactive oxygen species (ROS) plays an important role in hypertension, but clinical studies on chronic antioxidant therapy of hypertension fail to confirm this hypothesis. This discrepancy may be partly determined by the different effects of short and long-lasting treatment with antioxidants or scavengers. Elevated ROS production in hypertension need not be only harmful. It may also stimulate the activity of the antioxidant defence system and improve the nitric oxide (NO)/cyclic 3', 5'-guanosine monophosphate pathway, resulting in the establishment of a new equilibrium between enhanced oxidative load and the stimulated NO pathway, thus maintaining sufficient NO bioavailability. It has been suggested that antioxidant treatment might be beneficial for a short time, until increased NO generation predominates over ROS production. Further weakening of ROS formation by antioxidants may attenuate nuclear factor kappa B activation resulting in decreased endothelial NO synthase expression and activity. Prolonged antioxidant therapy may thus attenuate the beneficial regulatory effect of ROS, leading to decreased NO generation and the re-establishment of the undesirable disproportion between deleterious and protective forces. As a consequence prolonged antioxidant treatment in human hypertension may fail to provide the expected clinical profit.

Effects of long-term antioxidant supplementation and association of serum antioxidant concentrations with risk of metabolic syndrome in adults

BACKGROUND

Limited observational evidence suggests lower antioxidant concentrations in individuals with the metabolic syndrome (MetS); few randomized controlled trials have addressed the effect of multiple antioxidants on the risk of MetS.

OBJECTIVE

The objective was to examine the effect of antioxidant supplementation for 7.5 y on the incidence of MetS and the epidemiologic association between baseline serum antioxidant concentrations and the prospective risk of MetS.

DESIGN

Adults (n = 5220) participating in the SUpplementation en VItamines et Minéraux AntioXydants (SU.VI.MAX) primary prevention trial were randomly assigned to receive a supplement containing a combination of antioxidants (vitamins C and E, beta-carotene, zinc, and selenium) at nutritional doses or a placebo. Subjects were free of MetS at baseline and were followed for 7.5 y.

RESULTS

Antioxidant supplementation for 7.5 y did not affect the risk of MetS. Baseline serum antioxidant concentrations of beta-carotene and vitamin C, however, were negatively associated with the risk of MetS; the adjusted odds ratios (and 95% CIs) for the highest compared with the lowest tertile were 0.34 (0.21, 0.53; P for trend = 0.0002) and 0.53 (0.35, 0.80; P for trend = 0.01), respectively. Baseline serum zinc concentrations were positively associated with the risk of developing MetS; the adjusted odds ratio (and 95% CI) for the highest compared with the lowest tertile was 1.81 (1.20, 2.72; P for trend = 0.01).

CONCLUSIONS

The experimental finding of no beneficial effects of antioxidant supplementation in a generally well-nourished population is consistent with recent reports of a lack of efficacy of antioxidant supplements. However, the relations observed between the risk of MetS and baseline serum antioxidant concentrations, which probably reflect associations with overall dietary patterns, do support the current recommendations to consume antioxidant-rich foods. This trial was registered at clinicaltrials.gov as NCT00272428.

Molecular mechanisms of hypertension: role of Nox family NADPH oxidases

PURPOSE OF REVIEW

Molecular mechanisms contributing to the pathoetiology of hypertension are complex, involving many interacting systems such as signaling through G protein-coupled receptors, the renin-angiotensin system, vascular inflammation and remodeling, vascular senescence and aging and developmental programming, as highlighted in the current issue of the journal. Common to these systems is NADPH oxidase-derived reactive oxygen species (ROS). This editorial highlights current concepts relating to the production of ROS in hypertension and focuses on the Nox family NADPH oxidases, major sources of free radicals in the cardiovascular and renal systems.

RECENT FINDINGS

ROS play a major role as intracellular signaling molecules to regulate normal biological cellular responses. In pathological conditions, loss of redox homeostasis contributes to vascular oxidative damage. Recent evidence indicates that specific enzymes, the Nox family of NADPH oxidases, have the sole function of generating ROS in a highly regulated fashion in physiological conditions, and that in disease states, hyperactivation of Noxes contributes to oxidative stress and consequent cardiovascular and renal injury. The Nox family comprises seven members, Nox1-Nox7. Nox1, Nox2 (gp91phox-containing NADPH oxidase), Nox4 and Nox5 have been identified in the cardiovascular-renal systems and have been implicated in the pathophysiology of cardiovascular and renal disease.

SUMMARY

Noxes, which are differentially regulated in hypertension, are major sources of cardiovascular and renal oxidative stress. This has evoked considerable interest because of the possibilities that therapies targeted against specific Nox isoforms to decrease ROS generation or to increase nitric oxide availability or both may be useful in minimizing vascular injury and renal dysfunction, and thereby prevent or regress target organ damage associated with hypertension.

Oxidative stress and hypertension

This review has summarized some of the data supporting a role of ROS and oxidant stress in the genesis of hypertension. There is evidence that hypertensive stimuli, such as high salt and angiotensin II, promote the production of ROS in the brain, the kidney, and the vasculature and that each of these sites contributes either to hypertension or to the untoward sequelae of this disease. Although the NADPH oxidase in these various organs is a predominant source, other enzymes likely contribute to ROS production and signaling in these tissues. A major clinical challenge is that the routinely used antioxidants are ineffective in preventing or treating cardiovascular disease and hypertension. This is likely because these drugs are either ineffective or act in a non-targeted fashion, such that they remove not only injurious ROS Fig. 5. Proposed role of T cells in the genesis of hypertension and the role of the NADPH oxidase in multiple cells/organs in modulating this effect. In this scenario, angiotensin II stimulates an NADPH oxidase in the CVOs of the brain, increasing sympathetic outflow. Sympathetic nerve terminals in lymph nodes activate T cells, and angiotensin II also directly activates T cells. These stimuli also activate expression of homing signals in the vessel and likely the kidney, which attract T cells to these organs. T cells release cytokines that stimulate the vessel and kidney NADPH oxidases, promoting vasoconstriction and sodium retention. SFO, subfornical organ. 630 Harrison & Gongora but also those involved in normal cell signaling. A potentially important and relatively new direction is the concept that inflammatory cells such as T cells contribute to hypertension. Future studies are needed to understand the interaction of T cells with the CNS, the kidney, and the vasculature and how this might be interrupted to provide therapeutic benefit.

Circulating carotenoid concentrations and incident hypertension: the Coronary Artery Risk Development in Young Adults (CARDIA) study

BACKGROUND

Several epidemiological studies have demonstrated that carotenoid concentrations relate inversely to cardiovascular disease incidence. Thus, we examined the association of circulating carotenoids with hypertension, a major macrovascular disease risk factor.

METHODS

Black and White men and women in the Coronary Artery Risk Development in Young Adults Study, aged 18-30 years at recruitment (1985-1986) from four US cities, were investigated over 20 years. At years 0, 7, and 15, we determined the relationships of the sum of four serum carotenoids (alpha-carotene, beta-carotene, lutein/zeaxanthin, cryptoxanthin) and of lycopene with incident hypertension using proportional hazards regression models.

RESULTS

In 4412 participants, year 0 sum of four carotenoids was significantly inversely associated with 20-year hypertension incidence after adjustment for baseline systolic blood pressure and other confounding factors (relative hazard per SD increase of sum of four carotenoids: 0.91; 95% confidence interval = 0.84-0.99). The inverse relationships persisted in time-dependent models updating year 0 sum of four carotenoids with year 7 and year 15 values (relative hazard per SD increase of sum of four carotenoids: 0.84; 95% confidence interval = 0.77-0.92). Lycopene was unrelated to hypertension in any model.

CONCLUSION

Those individuals with higher concentrations of sum of carotenoids, not including lycopene, generally had lower risk for future hypertension.

Is the anti-hypertensive effect of dietary supplements via aldehydes reduction evidence based? A systematic review

Growing evidence indicates that insulin resistance and oxidative stress are involved in the pathogenesis of essential hypertension. In insulin-resistant states, like obesity and type 2 diabetes, altered glucose metabolism may lead to increased formation of methylglyoxal and other ketoaldehydes. Animal studies have shown that increased levels of endogenous aldehydes may lead to hypertension and oxidative stress. In animal models, the administration of vitamin C, vitamin B6 or alpha-lipoic acid reduced tissue levels of aldehydes, prevented oxidative stress, and lowered blood pressure. The purpose of this review article is to critically evaluate the available evidence for the role of dietary supplements in hypertension treatment.

The effects of natural antioxidants from tomato extract in treated but uncontrolled hypertensive patients

PURPOSE

To evaluate the effect of adding tomato extract to the treatment regime of moderate hypertensives with uncontrolled blood pressure (BP) levels.

METHODS

Fifty four subjects with moderate HT treated with one or two antihypertensive drugs were recruited and 50 entered two double blind cross-over treatment periods of 6 weeks each, with standardized tomato extract or identical placebo. Plasma concentrations of lycopene, nitrite and nitrate were measured and correlated with BP changes.

RESULTS

There was a significant reduction of systolic BP after 6 weeks of tomato extract supplementation, from 145.8 +/- 8.7 to 132.2 +/- 8.6 mmHg (p < 0.001) and 140.4 +/- 13.3 to 128.7 +/- 10.4 mmHg (p < 0.001) in the two groups accordingly. Similarly, there was a decline in diastolic BP from 82.1 +/- 7.2 to 77.9 +/- 6.8 mmHg (p = 0.001) and from 80.1 +/- 7.9 to 74.2 +/- 8.5 mmHg (p = 0.001). There was no significant change in systolic and diastolic BP during the placebo period. Serum lycopene level increased from 0.11 +/- 0.09 at baseline, to 0.30 +/- 01.3 micromol/L after tomato extract therapy (p < 0.001). There was a significant correlation between systolic BP and lycopene levels (r = -0.49, p < 0.001).

CONCLUSIONS

Tomato extract when added to patients treated with low doses of ACE inhibition, calcium channel blockers or their combination with low dose diuretics, had a clinically significant effect-reduction of BP by more than 10 mmHg systolic and more than 5 mmHg diastolic pressure. No side-effects to treatment were recorded and the compliance with treatment was high. The significant correlation between systolic blood pressure values and level of lycopene suggest the possibility of cause-effect relationships.

Fruit and vegetable consumption and the risk of hypertension determined by self measurement of blood pressure at home: the Ohasama study

It is well recognized that high fruit and vegetable consumption is associated with a reduction of blood pressure (BP) measured by conventional BP measurement in Western countries; however, there is little evidence about these associations in other regions and there have been no reports on these associations using self-measured BP at home (home BP). The objective of this work was to investigate the associations of fruit and vegetable consumption and their related micronutrients with the reduction of hypertension risk by using home BP in Japanese residents. Data were obtained from 1,569 residents aged 35 and over who measured their home BP in a general population of Ohasama, Japan. Dietary intake was measured using a 141-item food-frequency questionnaire (FFQ) and then subjects were divided into tertiles according to fruit, vegetable, potassium, vitamin C, and beta-carotene consumption. Hypertension was defined as home systolic/ diastolic BP > or = 135/85 mmHg and/or the use of antihypertensive medication. The prevalence of home hypertension was 39.4% for men and 29.3% for women. After adjustment for all potential confounding factors, the highest-tertile consumptions of fruits, vegetables, potassium, and vitamin C were associated with a significantly lower risk of hypertension (45%, 38%, 46%, and 43% lower risk of home hypertension, respectively). In conclusion, this cross-sectional study based on home BP measurement suggests that high-level consumptions of fruits, vegetables, potassium, and vitamin C are associated with a significantly lower risk of hypertension.

The role of selenium in chronic disease

Selenium functions as a part of proteins known as selenoproteins. Through these selenoproteins, selenium functions as a defensive mechanism for oxidative stress, for the regulation of thyroid hormone activity, and for the redox status of vitamin C and other molecules. In several of its roles, selenium functions as a dietary antioxidant and thus has been studied for its possible role in chronic diseases. This article reviews recent studies regarding selenium status or supplementation in hypertension, cardiovascular disease, cancer, and diabetes mellitus. A few studies regarding aging and mortality are also included. What can be ascertained from this current review is that the maintenance of adequate selenium nutriture and, at minimum, the prevention of a deficiency in selenium would be advisable for all individuals. In addition, the indiscriminant use of selenium supplements should be approached with caution until further randomized, controlled trials monitor the effects of such supplementation, especially on a long-term basis.

Role of Zinc and Selenium in Oxidative Stress and Immunosenescence: Implications for Healthy Ageing and Longevity

Ageing is an inevitable biological process with gradual and spontaneous biochemical and physiological changes and increased susceptibility to diseases. Some nutritional factors (zinc and selenium) may remodel these changes leading to a possible escaping of diseases with subsequent healthy ageing, because they are especially involved in improving immune functions as well as antioxidant defense. Experiments performed “in vitro” (human lymphocytes exposed to endotoxins) and “in vivo” (old mice or young mice fed with low zinc dietary intake) show that zinc is important for immune response both innate and adoptive. Selenium provokes zinc release by Metallothioneins (MT), via reduction of glutathione peroxidase. This fact is crucial in ageing because high MT may be unable to release zinc with subsequent low intracellular free zinc ion availability for immune response. Taking into account the existence of zinc transporters (ZnT and ZIP family) for cellular zinc efflux and influx, respectively, the association between ZnT and MT is important in maintaining satisfactory intracellular zinc homeostasis in ageing. Improved immune performance occur in elderly after physiological zinc supplementation, which also induces prolonged survival in old, nude and neonatal thymectomized mice. The association “zinc plus selenium” improves humoral immunity in old subjects after influenza vaccination. Therefore, zinc and selenium are relevant for immunosenescence in order to achieve healthy ageing and longevity.

Sex differences in control of blood pressure: role of oxidative stress in hypertension in females

In general, blood pressure is higher in normotensive men than in age-matched women, and the prevalence of hypertension in men is also higher until after menopause, when the prevalence of hypertension increases for women. It is likely then that the mechanisms by which blood pressure increases in men and women with aging may be different. Although clinical trials to reduce blood pressure with antioxidants have typically not been successful in human cohorts, studies in male rats suggest that oxidative stress plays an important role in mediating hypertension. The exact mechanisms by which oxidative stress increases blood pressure have not been completely elucidated. There may be several reasons for the discrepancies between clinical and animal studies. In this review, the data obtained in selected clinical and animal studies are discussed, and the hypothesis is put forward that oxidative stress may not be as important in mediating hypertension in females as has been shown previously in male rats. Furthermore, it is likely that differences in genetics, age, length of time with hypertension, endothelial dysfunction, and sex are all factored in to modulate the responses to antioxidants in humans. As such, future clinical trials should be designed and powered to evaluate the effects of oxidative stress on blood pressure separately in men and women.

Targeting reactive oxygen species in hypertension

Oxidative stress plays an important role in the pathogenesis of hypertension. A number of sources of reactive oxygen species have been identified including NADPH oxidase, endothelial NO synthase, and xanthine oxidase. Inhibitors of these systems reduce blood pressure in experimental models. Targeted overexpression of antioxidant systems and interference with expression of oxidant systems has also been successfully used in animal models of hypertension. It is expected that these strategies will eventually be translated to human disease, but currently, the specificity and toxicity of such measures are not yet fulfilling quality criteria for treatment of humans. In the meantime, presumably nontoxic measures, such as administration of antioxidant vitamins, are the only available treatments for oxidative stress in humans. In this review, we discuss strategies to target oxidative stress both in experimental models and in humans. We also discuss how patients could be selected who particularly benefit from antioxidant treatment. In clinical practice, diagnostic procedures beyond measurement of blood pressure will be necessary to predict the response to antioxidants; these procedures will include measurement of antioxidant status and detailed assessment of vascular structure and function.

One is okay, more is better? Pharmacological aspects and safe limits of nutritional supplements

The use of vitamins, minerals and other supplements has increased considerably during recent years. In the National Diet and Nutrition Survey of British adults aged 19-64 years 40% of those surveyed were taking supplements. In 2005 sales of dietary supplements in the UK were approximately pound sterling 325.7 x 106 in 'bricks and mortar' shops (excluding health food shops). The physiological effects of vitamins and minerals in amounts approximating to the UK reference nutrient intake or the EU RDA are well understood in terms of reducing the risk of micronutrient deficiency. However, the effects of vitamins, minerals and other supplements in larger amounts have attracted much attention in recent decades, and these effects, some of which may be pharmacological, are not as well categorised. Some of these effects are beneficial, some are not. Although vitamins and minerals and other supplements are generally safe at higher doses, there are some safety issues that are relevant in the context of the wide availability of supplements without a doctor's prescription. Thus, several authorities throughout the world have established upper limits (UL) for the intake of vitamins and minerals, and the EU is in the process of setting maximum permitted levels (MPL) for vitamins and minerals in food supplements. The present paper discusses the potential benefits and safety issues relating to the use of supplements at doses higher than the RDA. The rationale for the establishment of UL is also discussed, explaining the differences between the values set by different authorities and the expected guidance and legislation from the European Commission on MPL for vitamins and minerals in food supplements.

NADPH oxidases, reactive oxygen species, and hypertension: clinical implications and therapeutic possibilities

Reactive oxygen species (ROS) influence many physiological processes including host defense, hormone biosynthesis, fertilization, and cellular signaling. Increased ROS production (termed "oxidative stress") has been implicated in various pathologies, including hypertension, atherosclerosis, diabetes, and chronic kidney disease. A major source for vascular and renal ROS is a family of nonphagocytic NAD(P)H oxidases, including the prototypic Nox2 homolog-based NAD(P)H oxidase, as well as other NAD(P)H oxidases, such as Nox1 and Nox4. Other possible sources include mitochondrial electron transport enzymes, xanthine oxidase, cyclooxygenase, lipoxygenase, and uncoupled nitric oxide synthase. NAD(P)H oxidase-derived ROS plays a physiological role in the regulation of endothelial function and vascular tone and a pathophysiological role in endothelial dysfunction, inflammation, hypertrophy, apoptosis, migration, fibrosis, angiogenesis, and rarefaction, important processes underlying cardiovascular and renal remodeling in hypertension and diabetes. These findings have evoked considerable interest because of the possibilities that therapies against nonphagocytic NAD(P)H oxidase to decrease ROS generation and/or strategies to increase nitric oxide (NO) availability and antioxidants may be useful in minimizing vascular injury and renal dysfunction and thereby prevent or regress target organ damage associated with hypertension and diabetes. Here we highlight current developments in the field of reactive oxygen species and cardiovascular disease, focusing specifically on the recently identified novel Nox family of NAD(P)H oxidases in hypertension. We also discuss the potential role of targeting ROS as a therapeutic possibility in the management of hypertension and cardiovascular disease.