Beta-carotene and lung cancer in smokers: review of hypotheses and status of research

Antioxidants and neurodegenerative eye disease

Neurodegenerative ocular disorders mostly develop with aging and present great complications in the quality of life. Glaucoma and age-related macular degeneration (ARMD) rank as the third and fourth leading causes of blindness and low vision. Oxidative stress is one factor in the pathogenesis of neurodegenerative eye disease. In addition, ocular ischemia and neuroinflammation play an important role. It can be hypothesized that the influence of antioxidants through diet or oral supplementation can counteract the harmful effects of reactive oxygen species accumulated secondary to oxidative stress, ischemia, and inflammation. A range of studies has been published over the past decades focusing on the possible adjuvant effect of antioxidants in ARMD, while there were fewer reports on the potential role of antioxidants in glaucoma. Although certain reports demonstrated positive results, others were discouraging. As there is a controversy between the studies favoring and disfavoring supplementation with different types of antioxidants, it is important to revise the existing evidence on the role of antioxidants in neurodegenerative ocular disorders with a special focus on glaucoma and ARMD.

Discovering the direct relations between nutrients and epigenetic ageing

BACKGROUND

Along with the ageing of society, the absolute prevalence of age-related diseases is expected to rise, leading to a substantial burden on healthcare systems and society. Thus, there is an urgent need to promote healthy ageing. As opposed to chronological age, biological age was introduced to accurately represent the ageing process, as it considers physiological deterioration that is linked to morbidity and mortality risk. Furthermore, biological age responds to various factors, including nutritional factors, which have the potential to mitigate the risk of age-related diseases. As a result, a promising biomarker of biological age known as the epigenetic clock has emerged as a suitable measure to investigate the direct relations between nutritional factors and ageing, thereby identifying potential intervention targets to improve healthy ageing.

METHODS

In this study, we analysed data from 3,969 postmenopausal women from the Women's Health Initiative to identify nutrients that are associated with the rate of ageing by using an accurate measure of biological age called the PhenoAge epigenetic clock. We used Copula Graphical Models, a data-driven exploratory analysis tool, to identify direct relationships between nutrient intake and age-acceleration, while correcting for every variable in the dataset.

RESULTS

We revealed that increased dietary intakes of coumestrol, beta-carotene and arachidic acid were associated with decelerated epigenetic ageing. In contrast, increased intakes of added sugar, gondoic acid, behenic acid, arachidonic acid, vitamin A and ash were associated with accelerated epigenetic ageing in postmenopausal women.

CONCLUSION

Our study discovered direct relations between nutrients and epigenetic ageing, revealing promising areas for follow-up studies to determine the magnitude and causality of our estimated diet-epigenetic relationships.

The Role of Reactive Oxygen Species in Age-Related Macular Degeneration: A Comprehensive Review of Antioxidant Therapies

This review article delves into the intricate roles of reactive oxygen species (ROS) in the pathogenesis of age-related macular degeneration (AMD). It presents a detailed analysis of the oxidative stress mechanisms that contribute to the development and progression of these diseases. The review systematically explores the dual nature of ROS in ocular physiology and pathology, underscoring their essential roles in cellular signaling and detrimental effects when in excess. In the context of AMD, the focus is on the oxidative impairment in the retinal pigment epithelium and Bruch's membrane, culminating in the deterioration of macular health. Central to this review is the evaluation of various antioxidant strategies in the prevention and management of AMD. It encompasses a wide spectrum of antioxidants, ranging from dietary nutrients like vitamins C and E, lutein, and zeaxanthin to pharmacological agents with antioxidative properties. The review also addresses novel therapeutic approaches, including gene therapy and nanotechnology-based delivery systems, aiming to enhance antioxidant defense mechanisms in ocular tissues. The article concludes by synthesizing current research findings, clinical trial data, and meta-analyses to provide evidence-based recommendations. It underscores the need for further research to optimize antioxidant therapies, considering individual patient factors and disease stages. This comprehensive review thus serves as a valuable resource for clinicians, researchers, and healthcare professionals in ophthalmology, offering insights into the potential of antioxidants in mitigating the burden of AMD.

Screening and evaluation of antioxidants for retinal pigment epithelial cell protection: L-ergothioneine as a novel therapeutic candidate through NRF2 activation

The continual exposure of retinal tissues to oxidative stress leads to discernible anatomical and physiological alterations. Specifically, the onslaught of oxidative damage escalates the irreversible death of retinal pigmented epithelium (RPE) cells, pinpointed as the fundamental pathological event in dry age-related macular degeneration (AMD). There is a conspicuous lack of effective therapeutic strategies to counteract this degenerative process. This study screened a library of antioxidants for their ability to protect RPE cells against oxidative stress and identified L-ergothioneine (EGT) as a potent cytoprotective agent. L-ergothioneine provided efficient protection against oxidative stress-damaged RPE and maintained cell redox homeostasis and normal physiological functions. It maintained the normal structure of the retina in mice under oxidative stress conditions. Transcriptomic analysis revealed that EGT counteracted major gene expression changes induced by oxidative stress. It upregulated antioxidant gene expression and inhibited NRF2 translocation. The inhibition of NRF2 abolished EGT's protective effects, suggesting that NRF2 activation contributes to its mechanism of action. In conclusion, we identified EGT as a safe and effective small-molecule compound that is expected to be a novel antioxidative agent for treating AMD.

[Prevention and Treatment of Cancer with Vitamin A and Its Derivatives: Cell Differentiation and Proliferation]

Normal differentiation and proliferation of cells are essential for maintaining homeostasis. Following the successful completion of whole genome sequencing, protein modification has been attracted increasing attention in order to understand the roles of protein diversification in protein function and to elucidate molecular targets in mechanisms of signal transduction. Vitamin A is an essential nutrient for health maintenance. It is present as β-carotene in green and yellow vegetables and retinyl ester in animal products and absorbed into the body from the intestines. After ingestion, it is converted to retinol and oxidized in target cells to retinal, which plays critical roles in vision. It is then further oxidized to retinoic acid (RA), which exhibits a number of effects prior to being metabolized by cytochrome P450 and excreted from the body. Since RA exhibits cell differentiation-inducing actions, it is used as a therapeutic agent for patients with acute promyelocytic leukemia. The current paper describes: (1) HL60 cell differentiation and cell differentiation induction therapy by RA; (2) roles played by RA and retinal and their mechanisms of action; (3) retinoylation, post-translational protein-modified by RA, a novel non-genomic RA mechanism of action without RA receptor; (4) new actions of β-carotene and retinol in vivo and (5) potent anticancer effects of p-dodecylaminophenol (p-DDAP), a novel vitamin A derivative created from the RA derivative fenretinide. We propose that nutritional management of vitamin A can be effective at preventing and treating diseases, and that p-DDAP is a promising anticancer drug.

Association of Dietary and Supplement Intake of Antioxidants with Risk of Dementia: A Meta-Analysis of Cohort Studies

Background

Dementia is a neuropsychiatric disorder with cognitive decline due to multiple factors. With the arrival of the aging population, the incidence of dementia has gradually increased. There is still no effective treatment for dementia, and therefore, the prevention of dementia has become crucial. Oxidative stress is considered to be one of the pathogenesis of dementia; therefore, antioxidant therapy and prevention of dementia have been gradually proposed.

Objective

Our meta-analysis aimed to investigate the association of antioxidants with risk of dementia.

Methods

We searched PubMed, Embase, and Web of Science databases for articles on antioxidants associated with dementia risk, and those containing cohort studies with high-dose versus low-dose controls were included in our meta-analysis. The resulting risk ratios (RR) and hazard ratios (HR) and 95% confidence intervals were statistically analyzed using Stata12.0 free software.

Results

A total of 17 articles were included in this meta-analysis. Of 98,264 participants, 7,425 had dementia after 3-23 years of follow-up. The results of the meta-analysis showed a trend towards a lower incidence of dementia with high intake of antioxidants (RR = 0.84, 95% CI 0.77-1.19 I2 = 54.6%), but this was not statistically significant. High antioxidant intake significantly reduced the incidence of Alzheimer 's disease (RR = 0.85, 95% CI 0.79-0.92 I2 = 45.5%), and we additionally carried out subgroup analyses by nutrient type, diet or supplement, region, and study quality score.

Conclusion

Dietary intake of antioxidants or supplements reduces both the risk of dementia and the risk of Alzheimer's disease.

Associations of Dietary Intakes of Carotenoids and Vitamin A with Lung Cancer Risk in a Low-Income Population in the Southeastern United States

Observational studies found inverse associations of dietary carotenoids and vitamin A intakes with lung cancer risk. However, interventional trials among high-risk individuals showed that β-carotene supplements increased lung cancer risk. Most of the previous studies were conducted among European descendants or Asians. We prospectively examined the associations of lung cancer risk with dietary intakes of carotenoids and vitamin A in the Southern Community Cohort Study, including 65,550 participants with 1204 incident lung cancer cases. Multivariate Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Lung cancer cases had lower energy-adjusted dietary intakes of all carotenoids and vitamin A than non-cases. However, dietary intakes of carotenoids and vitamin A were not associated with overall lung cancer risk. A significant positive association of dietary vitamin A intake with lung cancer risk was observed among current smokers (HRQ4 vs. Q1 = 1.23; 95% CI: 1.02-1.49; Ptrend = 0.01). In addition, vitamin A intake was associated with an increased risk of adenocarcinoma among African Americans (HRQ4 vs. Q1 = 1.55; 95%CI: 1.08-2.21; Ptrend = 0.03). Dietary lycopene intake was associated with an increased risk of lung cancer among former smokers (HRQ4 vs. Q1 = 1.50; 95% CI: 1.04-2.17; Ptrend = 0.03). There are positive associations of dietary β-cryptoxanthin intake with squamous carcinoma risk (HRQ4 vs. Q1 = 1.49; 95% CI: 1.03-2.15; Ptrend = 0.03). Further studies are warranted to confirm our findings.

Carotenoid content and composition: A special focus on commercially important fish and shellfish

Carotenoids are natural pigments that provide many health benefits to living organisms. Although terrestrial plants are the major dietary source of carotenoids for humans, aquatic animals (especially fish and shellfish) are equally important because they are rich in certain important carotenoids lacking in fruits and vegetables. Although extensive research has focused on exploring the carotenoid content and composition in fish and shellfish, this information is poorly organized. This paper reviews the scientific evidence for the carotenoid content and composition in fish and shellfish. It makes serious attempts to summarize the relevant data published on specific research questions in order to improve the understanding of various evidence to clarify the research status of carotenoids in fish and shellfish and defining topics for future studies. From the analysis of published data, it is obvious that most fish and shellfish are rich in complex carotenoids (e.g. astaxanthin, fucoxanthin, fucoxanthinol, lutein). These carotenoids have stronger antioxidant effect, higher efficiency in removing the singlet oxygen and the peroxyl radicals, and have a variety of health benefits. Carotenoid levels in fish and shellfish depend on genotype, climatic conditions of the production area, storage and cooking methods. However, the information of the bioavailability of fish/shellfish carotenoids to human is very limited, which hinders the actual contributions to health. The findings of this study can be used as a guide to select appropriate fish and shellfish as dietary sources of carotenoids, and provide information about potential fish and shellfish species for aquaculture to produce carotenoids to meet part of the growing demand for natural carotenoids.

Effects of Oral Multi-Vitamin Multi-Mineral Supplement Formulations on Laboratory Outcomes and Quality of Life: A Quasi-Experimental Study

Background

Multi-vitamin multi-mineral (MVMM) products often come in several single-substance capsules from different manufacturers. However, attempts to mix several vitamins and minerals into one MVMM product have been complicated and often involve legal concerns. This study aimed to comparatively investigate the changes in laboratory parameters and the quality of life (QOL) among individuals who received different MVMM formulations.

Methods

This three-arm non-randomized controlled trial was conducted at VitalLife Scientific Wellness Center (VSWC), Bangkok, Thailand. A total of 72 healthy adult individuals with total serum 25-(OH)D level of 20–29 ng/ml were invited to choose from the three available options, namely, (1) Hydro-Cell-Key (HCK®, Hepart AG, Switzerland) contains vitamin D3 2,000 IU, vitamin C 1,000 mg, vitamin E 166 mg, vitamin A 1 mg, coenzyme Q10 30 mg, natural carotenoids 8 mg, and citrus flavonoids 200 mg in granule formulation; (2) VTL-7 (VWSC) contains similar vitamins and minerals but in capsule formulation; and (3) placebo capsule (no supplement). The 36-Item Short-Form Health Survey (SF-36) was used to measure QOL at baseline, month 3 and 6. A generalized estimating equation (GEE) was used to compare the repeated-measure outcomes across the three groups. This study was registered at the Thai Clinical Trial Registration (TCTR20190205002) and approved by the Bumrungrad International Institutional Review Board (BI-IRB No.258-10-18PhFub).

Results

Both VTL-7 and HCK saw a significantly higher increase in vitamin D than placebo at months 3 and 6, i.e., VTL-7 from 25.15 ± 2.13 to 35.53 ± 6.11 (p < 0.001) and 33.38 ± 6.89 (p < 0.001); HCK from 24.25 ± 3.08 to 28.43 ± 5.93 (p = 0.005) and 27.40 ± 5.24 (p = 0.012); and placebo from 24.00 ± 2.73 to 23.05 ± 4.39 (p = 0.273) and 22.30 ± 6.23 (p = 0.200), respectively. Similarly, β-carotenoids of VTL-7 vs. HCK groups significantly increased from 0.88 ± 0.68 vs. 0.94 ± 0.55 at baseline to 3.03 ± 1.79 (p < 0.001) vs. 1.09 ± 0.61 (p = 0.125) and 3.26 ± 1.74 (p < 0.001) vs. 1.15 ± 0.66 (p = 0.064), respectively. These findings were corroborated through the GEE analysis. Other micronutrients at months 3 and 6 did not increase significantly from baseline in any group. The overall QOL among the three groups in terms of physical (p = 0.560) and mental (p = 0.750) health increased but was not statistically significant.

Conclusion

The supplements of MVMM in capsule formulation increased the serum levels of some micronutrients to a higher extent than that of granule formulation. Participant adherence remains a potential confounder and should be further explored.

Clinical Trial Registration

identifier: TCTR20190205002.

Therapeutic promise of carotenoids as antioxidants and anti-inflammatory agents in neurodegenerative disorders

Neurodegenerative disorders (NDs) including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis have various disease-specific causal factors and pathological features. A very common characteristic of NDs is oxidative stress (OS), which takes place due to the elevated generation of reactive oxygen species during the progression of NDs. Furthermore, the pathological condition of NDs including an increased level of protein aggregates can further lead to chronic inflammation because of the microglial activation. Carotenoids (CTs) are naturally occurring pigments that play a significant role in averting brain disorders. More than 750 CTs are present in nature, and they are widely available in plants, microorganisms, and animals. CTs are accountable for the red, yellow, and orange pigments in several animals and plants, and these colors usually indicate various types of CTs. CTs exert various bioactive properties because of its characteristic structure, including anti-inflammatory and antioxidant properties. Due to the protective properties of CTs, levels of CTs in the human body have been markedly linked with the prevention and treatment of multiple diseases including NDs. In this review, we have summarized the relationship between OS, neuroinflammation, and NDs. In addition, we have also particularly focused on the antioxidants and anti-inflammatory properties of CTs in the management of NDs.

Redox regulation by carotenoids: Evidence and conflicts for their application in cancer

Carotenoids have been constantly investigated since the early fifty for their chemical, biochemical and biological properties being presence in foods. Among the more than 1100 carotenoids synthesized by plants and microorganisms, approximately 50 are present in the human diet, and about 20 can be detected in human blood and tissues. Review articles that discuss the anticancer and cancer preventing activity of phytochemicals have often in common the difficulty to find a coherency between the results deriving from experimental studies and the controversial or weak clinical indications arising from epidemiological and interventional studies. In this scenario, the class of carotenoids does not represent an exception. In fact, according with World Cancer Research Fund, strong evidence exists that high-dose supplementation of β-carotene increases the risk of lung cancer, while for other types of cancer, the protective or harmful effects of food-containing carotenoids or carotenoid supplements have been considered limited, suggestive or unlikely. The analysis of the mechanistic evidence is complicated by the double nature of carotenoids being molecules acting either as antioxidant or pro-oxidant compounds. The present review analyzes the ambiguity and the unexpected results deriving from the epidemiological and interventional studies and discusses how the effects of carotenoids on cancer risk can be explained by understanding their capacity to modulate the cellular antioxidant response, depending on the concentration applied and the cellular metabolism. In the final part, a new global approach is proposed to study the contribution of carotenoids, but also of other phytochemicals, to disease prevention, including cancer.

α-Amylase inhibition, cytotoxicity and influence of the in vitro gastrointestinal digestion on the bioaccessibility of phenolic compounds in the peel and seed of Theobroma grandiflorum

The aim of this work was to evaluate the bioaccessibility, cytotoxicity, antioxidant and antidiabetic potential of peel and seeds of cupuassu (Theobroma grandiflorum). Thus, the extracts of cupuassu were evaluated for inhibition of α-amylase, cytotoxicity, and bioaccessibility after gastrointestinal digestion and probiotic fermentation (Lactobacillus delbrueckii, Lactobacillus jhonsoni, Lactobacillus rhamus and Bifidobacterium longum). Digestion increased concentrations of phenolics, showing bioaccessibility of up to 274.13% (total phenolics) and 1105.15% (ORAC). β-carotene, quinic, tartaric, malic, citric, epicatechin, ethyl gallate, epigallocatechin gallate, gallic acid, pyrocatechol, vanillin, ramnetine were the main compounds while the epicatechin, ethyl gallate, gallic acid and pyrocatechol were the major effective phenolic compounds. The extracts did not show toxic effects and the cupuassu seeds showed 97% inhibition of α-amylase and 47.91% bioaccessibility of pyrocatechol. This study suggests that cupuassu extracts are sources of natural antioxidants with promising antidiabetic potential, and probiotics are able to increase phenolic compounds, responsible for health benefits.

Management of Oral Potentially Malignant Disorders

Patients with oral potentially malignant disorders (OPMDs), including oral leukoplakia and erythroplakia, proliferative verrucous leukoplakia, oral submucous fibrosis, and oral lichen planus/lichenoid lesions can be challenging to manage. A small proportion will undergo cancer development and determining a patient's cancer risk is key to making management decisions. Yet, our understanding of the natural history of OPMDs has not been fully elucidated, and a precision approach based on the integration of numerous predictive markers has not been validated by prospective studies. Evidence-based health promotion by clinicians and healthcare systems is not embraced universally. Medical and surgical interventions evaluated by rigorous research measuring important endpoints, such as cancer development, mortality, or survival are difficult and expensive to run. Most of these studies employ non-ideal surrogate endpoints and have deep methodologic flaws. Diagnostic criteria for enrolling research subjects are not uniform, and patients with the highest risk for cancer development comprise small proportions of those enrolled. Few studies explore quality of life and patient preferences. It is time to rethink how we approach the management of these patients, across each OPMD, and considering the healthcare infrastructure and cost effectiveness. Global networks with well-characterized patient populations with OPMDs and well-designed interventional trials using validated outcome measures are needed.

New Insights into Molecular Mechanism behind Anti-Cancer Activities of Lycopene

Lycopene is a well-known compound found commonly in tomatoes which brings wide range of health benefits against cardiovascular diseases and cancers. From an anti-cancer perspective, lycopene is often associated with reduced risk of prostate cancer and people often look for it as a dietary supplement which may help to prevent cancer. Previous scientific evidence exhibited that the anti-cancer activity of lycopene relies on its ability to suppress oncogene expressions and induce proapoptotic pathways. To further explore the real potential of lycopene in cancer prevention, this review discusses the new insights and perspectives on the anti-cancer activities of lycopene which could help to drive new direction for research. The relationship between inflammation and cancer is being highlighted, whereby lycopene suppresses cancer via resolution of inflammation are also discussed herein. The immune system was found to be a part of the anti-cancer system of lycopene as it modulates immune cells to suppress tumor growth and progression. Lycopene, which is under the family of carotenoids, was found to play special role in suppressing lung cancer.

Vitamin A in health care: Suppression of growth and induction of differentiation in cancer cells by vitamin A and its derivatives and their mechanisms of action

Vitamin A is an important micro-essential nutrient, whose primary dietary source is retinyl esters. In addition, β-carotene (pro-vitamin A) is a precursor of vitamin A contained in green and yellow vegetables that is converted to retinol in the body after ingestion. Retinol is oxidized to produce visual retinal, which is further oxidized to retinoic acid (RA), which is used as a therapeutic agent for patients with promyelocytic leukemia. Thus, the effects of retinal and RA are well known. In this paper, we will introduce (1) vitamin A circulation in the body, (2) the actions and mechanisms of retinal and RA, (3) retinoylation: another RA mechanism not depending on RA receptors, (4) the relationship between cancer and actions of retinol or β-carotene, whose roles in vivo are still unknown, and (5) anti-cancer actions of vitamin A derivatives derived from fenretinide (4-HPR). We propose that vitamin A nutritional management is effective in the prevention of cancer.

Antioxidant Activity and Healthy Benefits of Natural Pigments in Fruits: A Review

Natural pigments, including carotenoids, flavonoids and anthocyanidins, determine the attractive color of fruits. These natural pigments are essential secondary metabolites, which play multiple roles in the whole life cycle of plants and are characterized by powerful antioxidant activity. After decades of research and development, multiple benefits of these natural pigments to human health have been explored and recognized and have shown bright application prospects in food, medicine, cosmetics and other industries. In this paper, the research progress of natural fruit pigments in recent years was reviewed, including the structural characteristics and classification, distribution in fruits and analysis methods, biosynthetic process, antioxidant capacity and mechanism, bioaccessibility and bioavailability, and health benefits. Overall, this paper summarizes the recent advances in antioxidant activity and other biological functions of natural fruit pigments, which aims to provide guidance for future research.

From carotenoid intake to carotenoid blood and tissue concentrations - implications for dietary intake recommendations

There is uncertainty regarding carotenoid intake recommendations, because positive and negative health effects have been found or are correlated with carotenoid intake and tissue levels (including blood, adipose tissue, and the macula), depending on the type of study (epidemiological vs intervention), the dose (physiological vs supraphysiological) and the matrix (foods vs supplements, isolated or used in combination). All these factors, combined with interindividual response variations (eg, depending on age, sex, disease state, genetic makeup), make the relationship between carotenoid intake and their blood/tissue concentrations often unclear and highly variable. Although blood total carotenoid concentrations <1000 nmol/L have been related to increased chronic disease risk, no dietary reference intakes (DRIs) exist. Although high total plasma/serum carotenoid concentrations of up to 7500 nmol/L are achievable after supplementation, a plateauing effect for higher doses and prolonged intake is apparent. In this review and position paper, the current knowledge on carotenoids in serum/plasma and tissues and their relationship to dietary intake and health status is summarized with the aim of proposing suggestions for a "normal," safe, and desirable range of concentrations that presumably are beneficial for health. Existing recommendations are likewise evaluated and practical dietary suggestions are included.

Method for beta-carotene extraction from processed baby foods as a model for plant-based fatty food products

Reliable quantitative determination of carotenoids in complex food matrices such as processed baby food products is challenging because of their incorporation in rigid cellular structures, their sensitivity to oxidation and their lipophilic character. A one-pot liquid-liquid β-carotene extraction procedure is described for solid baby foods, in the presence of enzymes (Clara-Diastase and Rapidase) facilitating matrix disintegration. The combined extraction and enzymatic dissolution not only protected β-carotene from oxidation compared to the sequential approach, but also reduced the use of solvents and amount of filtrations steps, favouring a higher recovery. The addition of phenolic antioxidants (BHT, TBHQ and BHA) to calibration solutions and during the procedure at 25 mg/mL resulted in an up to 2.5-fold higher absorbance of β-carotene solutions which was not observed for trans-β-apo-8'-carotenal (used as internal standard) solutions. When applying the full procedure on β-carotene spiked sunflower oil, an apparent recovery of 80% for β-carotene was obtained. Finally, this protocol was applied to 50 vegetable-based and 22 fruit-based processed baby foods (range 0 to 1179 and 504 µg/100 g, respectively), and it was concluded that this extraction procedure may be used for similar processed foods products. The procedure proved to be sensitive (LOD = 0.12 µg/mL) and reproducible (CV for baby foods: 4-10%).

Carotenoids: Importance in Daily Life-Insight Gained from EPR and ENDOR

Carotenoids are indispensable molecules for life. They are present everywhere in plants, algae, bacteria whom they protect against free radicals and oxidative stress. Through the consumption of fruits and vegetables and some carotenoid-containing fish, they are introduced into the human body and, similarly, protect it. There are numerous health benefits associated with the consumption of carotenoids. Carotenoids are antioxidants but at the same time they are prone to oxidation themselves. Electron loss from the carotenoid forms a radical cation. Furthermore, proton loss from a radical cation forms a neutral radical. In this mini-review, we discuss carotenoid radicals studied in our groups by various physicochemical methods, namely the radical cations formed by electron transfer and neutral radicals formed by proton loss from the radical cations. They contain many similar hyperfine couplings due to interactions between the electron spin and numerous protons in the carotenoid. Different EPR and ENDOR methods in combination with DFT calculations have been used to distinguish the two independent carotenoid radical species. DFT predicted larger coupling constants for the neutral radical compared to the radical cation. Previously, INDO calculations miss assigned the large couplings to the radical cation. EPR and ENDOR have aided in elucidating the physisorb, electron and proton transfer processes that occur when carotenoids are adsorbed on solid artificial matrices, and predicted similar reactions in aqueous solution or in plants. After years of study of the physicochemical properties of carotenoid radicals, the different published results start to merge together for a better understanding of carotenoid radical species and their implication in biological systems. Up until 2008, the radical chemistry in artificial systems was elucidated but the correlation between quenching ability and neutral radical formation was an inspiration to look for these radical species in vivo. In addition, the EPR spin-trapping technique has been applied to study inclusion complexes of carotenoids with different delivery systems.

The colorful world of carotenoids: a profound insight on therapeutics and recent trends in nano delivery systems

The therapeutic effects of carotenoids as dietary supplements to control or even treat some specific diseases including diabetic retinopathy, cardiovascular diseases, bacterial infections, as well as breast, prostate, and skin cancer are discussed in this review and also thoughts on future research for their widespread use are emphasized. From the stability standpoint, carotenoids have low bioavailability and bioaccessibility owing to their poor water solubility, deterioration in the presence of environmental stresses such as oxygen, light, and high heat as well as rapid degradation during digestion. Nanoencapsulation technologies as wall or encapsulation materials have been increasingly used for improving food product functionality. Nanoencapsulation is a versatile process employed for the protection, entrapment, and the delivery of food bioactive products including carotenoids from diverse environmental conditions for extended shelf lives and for providing controlled release. Therefore, we present here, recent (mostly during the last five years) nanoencapsulation methods of carotenoids with various nanocarriers. To us, this review can be considered as the first highlighting not only the potential therapeutic effects of carotenoids on various diseases but also their most effective nanodelivery systems.HighlightsBioactive compounds are of deep interest to improve food properties.Carotenoids (such as β-carotene and xanthophylls) play indispensable roles in maintaining human health and well-being.A substantial research effort has been carried out on developing beneficial nanodelivery systems for various carotenoids.Nanoencapsulation of carotenoids can enhance their functional properties.Stable nanoencapsulated carotenoids could be utilized in food products.

Antioxidant supplements in age-related macular degeneration: are they actually beneficial?

Age-related macular degeneration (ARMD) is one of the prominent causes of central visual loss in the older age group in the urbanized, industrialized world. In recent years, many epidemiological studies and clinical trials have evaluated the role of antioxidants and micronutrients to prevent the progression of ARMD. In this article, we review some of these major studies. In addition, we review the absorption and bioavailability and possible undesirable effects of these nutrients after ingestion. The role of genotypes and inappropriate use of these supplements are also discussed. From all the above evidence, we conclude that it may not be prudent to prescribe these formulations without a proper assessment of the individual's health and dietary status. The effectiveness of all the components in antioxidant formulations is controversial. Thus, these supplements should not be prescribed just for the purpose of providing patients some kind of therapy, which may give a false sense of mental satisfaction.

Anti- and pro-oxidative mechanisms comparing the macular carotenoids zeaxanthin and lutein with other dietary carotenoids - a singlet oxygen, free-radical in vitro and ex vivo study

The interactions of dietary carotenoids, and particularly the xanthophylls in the macula, with singlet oxygen and three different oxy-radicals, (hydroxyl radical, nitrogen dioxide and the superoxide radical anion) are compared using pulsed laser and γ-techniques. The results give possible molecular mechanisms for the switch from anti-oxidant (protection) by carotenoids to pro-oxidant (damage) by carotenoids. The participation of oxygen in radical mechanisms in the presence of different carotenoids is compared for the different radicals. It is shown that the mechanistic role of oxygen differs very significantly for anti-/pro-oxidation by hydroxyl radicals when compared to nitrogen dioxide. Lutein was found to be an extremely good cell protector against hydroxyl radicals at all oxygen concentrations, including under physiological conditions.

Analysis of the Status of the Cutaneous Endogenous and Exogenous Antioxidative System of Smokers and the Short-Term Effect of Defined Smoking Thereon

The daily consumption of tobacco products leads to a boost in free radical production in tissues, promoting the risk for malignancies, metabolic alterations and chronic-inflammatory diseases. This study aimed to broaden the knowledge of the status of the antioxidative (AO) system in the skin, compared to the blood, of healthy appearing smokers. Both, the basic status compared to non-smokers and the short-term impact of controlled cigarette consumption in smokers were analyzed. Our study showed that the basic level of the AO system of smokers significantly differed from that of non-smokers. As determined by resonant Raman spectroscopy (RRS), the levels of exogenous AOs were decreased in both, the skin, in vivo (β-carotene and lycopene), and blood plasma (β-carotene only). In contrast, the levels of glutathione (GSH), the prototypical endogenous AO, which were analyzed by fluorimetric assays in cutaneous tape strips and blood plasma, were increased in the skin, although unchanged in the blood of smokers. Elevated cutaneous GSH levels were reflected by an elevated overall radical scavenging activity in the skin, as quantified by non-invasive electron paramagnetic resonance (EPR) spectroscopy. Analysis of the expression of selected stress-associated genes in blood immune cells by quantitative RT-PCR in subgroups of non-smokers and smokers additionally demonstrated the downregulation of AKR1C2 in smokers, and its negative correlation with blood plasma levels of the protective immune mediator interleukin-22, assessed by the ELISA technique. Controlled cigarette consumption did not alter exogenous or endogenous AOs in the skin of smokers, but decreased lycopene levels in blood plasma. Moreover, there was a decline in blood IL-22 levels, while no relevant response of blood cell gene expressions was found after the considered short time. Our data therefore demonstrate a strengthened endogenous AO status in the skin of smokers, which may indicate a long-term adaptation to chronic oxidative stress in this specific organ. While this effect was not clearly visible in the blood, this compartment seems to be useful as an immediate indicator of the body's AO consumption. Moreover, decreased levels of AKR1C2, which we show for the first time to be expressed in immune cells, may be a candidate marker for long-term smoking. In addition, this study demonstrates that the rate constant of a spin probe decline determined by EPR spectroscopy mainly represents the endogenous AO status of a tissue.

Serum Retinol and Risk of Overall and Site-Specific Cancer in the ATBC Study

Retinol, the most biologically active form of vitamin A, might influence cancer-related biological pathways. However, results from observational studies of serum retinol and cancer risk have been mixed. We prospectively examined serum retinol and risk of overall and site-specific cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (n = 29,104 men), conducted in 1985-1993, with follow-up through 2012. Serum retinol concentration was measured using reverse-phase high-performance liquid chromatography. Cox proportional hazards models estimated the association between baseline serum retinol quintile and overall and site-specific cancer risk in 10,789 cases. After multivariable adjustment, higher serum retinol was not associated with overall cancer risk (highest vs. lowest quintile: hazard ratio (HR) = 0.97, 95% confidence interval (CI): 0.91, 1.03; P for trend = 0.43). Higher retinol concentrations were, however, associated with increased risk of prostate cancer (highest vs. lowest quintile: HR = 1.28, 95% CI: 1.13, 1.45; P for trend < 0.0001) and lower risk of both liver and lung cancers (highest vs. lowest quintile: for liver, HR = 0.62, 95% CI: 0.42, 0.91; P for trend = 0.004; and for lung, HR = 0.80, 95% CI: 0.72, 0.88; P for trend < 0.0001). No associations with other cancers were observed. Understanding the mechanisms that underlie these associations might provide insight into the role of vitamin A in cancer etiology.

β-Carotene Supplementation and Lung Cancer Incidence in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study: The Role of Tar and Nicotine

INTRODUCTION

The Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study demonstrated that β-carotene supplementation increases lung cancer incidence in smokers. Further, cigarettes with higher tar and nicotine content are associated with a higher risk of lung cancer. However, no studies have examined whether the increased risk associated with β-carotene supplementation in smokers varies by the tar or nicotine content of cigarettes.

METHODS

The ATBC Study was a randomized, double-blind intervention trial conducted in southwest Finland. A total of 29 133 male smokers, aged 50-69 years, were enrolled and randomly assigned to one of four groups (α-tocopherol, β-carotene, both, or placebo). Cox proportional hazards models were used to estimate the hazard ratio (HR) and 95% confidence intervals (CI) of lung cancer risk by β-carotene trial assignment stratified by a priori categories of cigarette tar and nicotine content.

RESULTS

The β-carotene supplementation group had significantly higher risk of developing lung cancer in all categories of tar content (yes vs. no β-carotene supplementation-ultralight cigarettes [≤7 mg tar]: HR = 1.31, 95% CI = 0.91 to 1.89; nonfiltered cigarettes [≥21 mg tar]: HR = 1.22, 95% CI = 0.91 to 1.64; p for interaction = .91). Similarly, there was no interaction with nicotine content (yes vs. no β-carotene supplementation-ventilated cigarettes [≤0.8 µg nicotine]: HR = 1.23, 95% CI = 0.98 to 1.54; nonfiltered cigarettes [≥1.3 µg nicotine]: HR = 1.22, 95% CI = 0.91 to 1.64; p for interaction = .83).

CONCLUSION

These findings support the conclusion that supplementation with β-carotene increases the risk of lung cancer in smokers regardless of the tar or nicotine content of cigarettes smoked. Our data suggest that all smokers should continue to avoid β-carotene supplementation.

IMPLICATIONS

Previous studies demonstrated that β-carotene supplementation increases risk of lung cancer in smokers. This study moves the field forward by examining the potential for modification of risk of lung cancer with different levels of tar and nicotine in cigarettes smoked, as interaction with carcinogens in these components of cigarette smoke is hypothesized to be the mechanism by which β-carotene increases risk. Our study provides evidence that the increased risk of lung cancer in smokers who take β-carotene supplements is not dependent upon the tar or nicotine level of cigarettes smoked and suggests that all smokers should continue to avoid β-carotene supplementation.

The Benefits and Risks of Certain Dietary Carotenoids that Exhibit both Anti- and Pro-Oxidative Mechanisms-A Comprehensive Review

Carotenoid pigments, particularly β-carotene and lycopene, are consumed in human foodstuffs and play a vital role in maintaining health. β-carotene is known to quench singlet oxygen and can have strong antioxidant activity. As such, it was proposed that β-carotene might reduce the risk of cancer. Epidemiological studies found inverse relationships between cancer risk and β-carotene intake or blood levels. However, clinical trials failed to support those findings and β-carotene supplementation actually increased lung cancer incidence in male smokers. Early experimental animal studies found dietary β-carotene inhibited UV-induced skin cancers. Later studies found that β-carotene supplementation exacerbated UV-carcinogenic expression. The discrepancies of these results were related to the type of diet the animals consumed. Lycopene has been associated with reduced risk of lethal stage prostate cancer. Other carotenoids, e.g., lutein and zeaxanthin, play a vital role in visual health. Numerous studies of molecular mechanisms to explain the carotenoids' mode of action have centered on singlet oxygen, as well as radical reactions. In cellular systems, singlet oxygen quenching by carotenoids has been reported but is more complex than in organic solvents. In dietary β-carotene supplement studies, damaging pro-oxidant reactivity can also arise. Reasons for this switch are likely due to the properties of the carotenoid radicals themselves. Understanding singlet oxygen reactions and the anti-/pro-oxidant roles of carotenoids are of importance to photosynthesis, vision and cancer.

An Overview of Carotenoids, Apocarotenoids, and Vitamin A in Agro-Food, Nutrition, Health, and Disease

Carotenoids are fascinating compounds that can be converted into many others, including retinoids that also play key roles in many processes. Although carotenoids are largely known in the context of food science, nutrition, and health as natural colorants and precursors of vitamin A (VA), evidence has accumulated that even those that cannot be converted to VA may be involved in health-promoting biological actions. It is not surprising that carotenoids (most notably lutein) are among the bioactives for which the need to establish recommended dietary intakes have been recently discussed. In this review, the importance of carotenoids (including apocarotenoids) and key derivatives (retinoids with VA activity) in agro-food with relevance to health is summarized. Furthermore, the European Network to Advance Carotenoid Research and Applications in Agro-Food and Health (EUROCAROTEN) is introduced. EUROCAROTEN originated from the Ibero-American Network for the Study of Carotenoids as Functional Food Ingredients (IBERCAROT).

Bioinformatics Analysis of Stromal Molecular Signatures Associated with Breast and Prostate Cancer

This study aimed to identify stromal molecular signatures associated with breast and prostate cancer. The microarray data GSE26910 was downloaded from Gene Expression Omnibus database, including six invasive breast tumor stroma, six matched normal controls, six invasive prostate tumor stroma, and six matched controls. The differentially expressed genes (DEGs) in invasive breast and prostate tumors stroma were, respectively, identified. Then common stromal genes (B_P.DEGs) were further screened. Protein-protein interaction (PPI) network was constructed and Gene Ontology analysis was performed. Besides, gene-chemical interactions were mapped in Comparative Toxicogenomics Database to screen the chemicals related to feature genes. The results showed that, in total, 16 B_P.DEGs were identified. Thereinto, only seven B_P.DEGs were mapped into PPI, and only four functional modules (adenylate cyclase activating polypeptide 1 (pituitary) receptor type I (ADCYAP1R1) module, aspartoacylase (ASPA) module, glutathione S-transferase mu 5 (GSTM5) module, and periplakin (PPL) module) were involved in important biological processes associated with cancer progression. In addition, the chemicals, such as dihydrotestosterone, apocarotenal, testosterone, and progesterone, were screened for the roles of feature genes in the progression of breast and prostate cancer. In conclusion, ADCYAP1R1, GSTM5, and PPL were stromal molecular signatures and might play a key role in the progression of breast and prostate cancer.

Cruciferous Vegetables, Isothiocyanates, and Bladder Cancer Prevention

Bladder cancer is a significant health burden due to its high prevalence, risk of mortality, morbidity, and high cost of medical care. Epidemiologic evidence suggests that diets rich in cruciferous vegetables, particularly broccoli, are associated with lower bladder cancer risk. Phytochemicals in cruciferous vegetables, such as glucosinolates, which are enzymatically hydrolyzed to bioactive isothiocyanates, are possible mediators of an anticancer effect. In vitro studies have shown inhibition of bladder cancer cell lines, cell cycle arrest, and induction of apoptosis by these isothiocyanates, in particular sulforaphane and erucin. Although not yet completely understood, many mechanisms of anticancer activity at the steps of cancer initiation, promotion, and progression have been attributed to these isothiocyanates. They target multiple pathways including the adaptive stress response, phase I/II enzyme modulation, pro-growth, pro-survival, pro-inflammatory signaling, angiogenesis, and even epigenetic modulation. Multiple in vivo studies have shown the bioavailability of isothiocyanates and their antitumoral effects. Although human studies are limited, they support oral bioavailability with reasonable plasma and urine concentrations achieved. Overall, both cell and animal studies support a potential role for isothiocyanates in bladder cancer prevention and treatment. Future studies are necessary to examine clinically relevant outcomes and define guidelines on ameliorating the bladder cancer burden.

Vitamin and Mineral Supplement Use among Korean Adults: Baseline Data from the Trace Element Study of Korean Adults in Yeungnam Area

Although dietary supplement use is believed to improve health status, the efficacy and safety of its use remains controversial. This study aimed to investigate the contribution of consumption of vitamin and mineral supplements (VMS) to the total micronutrient intake. Study participants (n = 586) were selected from the ongoing prospective cohort study of the Korean population, and baseline information on current use of dietary supplements, types of supplements, frequency of use, dosage, duration, and brand name was collected. Dietary information was assessed using a 146-item semi-quantitative food frequency questionnaire. Approximately one-fourth of the participants were categorized as VMS users. The proportion of VMS use was significantly higher in women (p = 0.02), older participants (p = 0.002), and those with a higher income level (p = 0.03) than in non-users. All vitamin and mineral intakes of both groups met the recommended nutrient intake levels by food consumption alone, except for riboflavin, calcium, and magnesium. Approximately 0.7-3.4% of the VMS users had nutrient intake levels that exceeded the tolerable upper intake levels for vitamin A, E, C, iron, and iodine. Excessive use of VMS can lead to an increased risk for adverse health effects. The results of this study provide useful baseline data for establishing guidelines for the appropriate consumption and adequate intake levels of VMS.

Carotenoids from Marine Organisms: Biological Functions and Industrial Applications

As is the case for terrestrial organisms, carotenoids represent the most common group of pigments in marine environments. They are generally biosynthesized by all autotrophic marine organisms, such as bacteria and archaea, algae and fungi. Some heterotrophic organisms also contain carotenoids probably accumulated from food or partly modified through metabolic reactions. These natural pigments are divided into two chemical classes: carotenes (such as lycopene and α- and β-carotene) that are composed of hydrogen and carbon; xanthophylls (such as astaxanthin, fucoxanthin and lutein), which are constituted by hydrogen, carbon and oxygen. Carotenoids, as antioxidant compounds, assume a key role in the protection of cells. In fact, quenching of singlet oxygen, light capture and photosynthesis protection are the most relevant biological functions of carotenoids. The present review aims at describing (i) the biological functions of carotenoids and their benefits for human health, (ii) the most common carotenoids from marine organisms and (iii) carotenoids having large success in pharmaceutical, nutraceutical and cosmeceutical industries, highlighting the scientific progress in marine species cultivation for natural pigments production.

Fat-soluble micronutrients and metabolic syndrome

PURPOSE OF REVIEW

Metabolic syndrome (MetS) is associated with increased risk of obesity, type 2 diabetes mellitus and cardiovascular diseases. MetS prevalence has been associated with diet inadequacy. Conversely, the cumulative incidence of MetS has been inversely associated with a Mediterranean-style diet that includes many different health-beneficial nutrients. Adherence to a Mediterranean-style diet could reduce or at least stabilize metabolic risk factors.

RECENT FINDINGS

Low serum level of fat-soluble micronutrients, such as carotenoids, vitamin (vit) A, D and E, has been linked to MetS. Fat-soluble micronutrients could contribute to prevent MetS thanks to their antioxidant and anti-inflammatory properties (vit E, carotenoids) or to their central role as hormone regulators (vit D) and/or lipid metabolism and glucose homeostasis sensors (vit D and E).

SUMMARY

This review summarizes recent epidemiological studies linking fat-soluble micronutrients to MetS and highlights new evidence on their mechanisms of actions.

Evaluation and Management of Oral Potentially Malignant Disorders

Oral potentially malignant disorders (OPMDs) refer to epithelial lesions and conditions with an increased risk for malignant transformation; oral leukoplakia is the most commonly encountered. Overall, OPMDs have a low risk for malignant transformation, yet the challenge is the difficulty to reliably identify and predict which patients with OPMDs are at the highest risk for malignant transformation. Future research is needed to elucidate the molecular aspects of OPMDs, to improve current diagnostic strategies, leading to personalized management.

Identification and biological activities of carotenoids from the freshwater alga Oedogonium intermedium

The chemical and biological properties of carotenoids in the freshwater alga Oedogonium intermedium were investigated in this study. Carotenoids were extracted from the alga by dichloromethane and purified by saponification. The carotenoid content was determined both spectrometrically and by HPLC, the carotenoids identified by HPLC-PDA-APCI-IT-TOF-MS and the extracts analysed for several health-related bioactivities. The crude and saponified extracts contained 3,411.2±20.7 and 2,929.6±5.9µg carotenoids/g dry algal biomass, respectively. Seven major carotenoids were identified, namely neoxanthin, 9'-cis-neoxanthin, loroxanthin, violaxanthin, lutein, α-carotene and β-carotene, which were present in similar amounts in the alga. Both the crude and saponified carotenoid extracts exhibited significant antioxidant activities as well as potent inhibitory effects against several metabolically important enzymes including α-amylase, α-glucosidase, pancreatic lipase and hyaluronidase, but they were poor inhibitors of angiotensin converting enzyme (ACE). Oedogonium could be an important new source of carotenoids, specifically loroxanthin, which is lacking in terrestrial plants.

Association between lutein intake and lung function in adults: the Rotterdam Study

Lutein, a fat-soluble carotenoid with antioxidant properties, may have an effect on respiratory health. However, the evidence is inconsistent. We aimed to cross-sectionally investigate the association between lutein intake and lung function by measuring forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC% in adults (aged 45-79 years). We included 4402 participants from the Rotterdam Study, a prospective cohort study in The Netherlands. Lutein intake was assessed using a validated FFQ. Lung function was assessed using spirometry around the same time point as the dietary assessment. No independent association was found between lutein intake and FEV1 (-12·17 (95 % CI -34·21, 9·87) ml per sd increase in lutein) after adjustment for age, sex, height, cohort effect, ethnicity, education, weight, total daily energy intake, smoking status, physical activity, and intakes of fatty acids, dietary fibre, alcohol, β-carotene, β-crypotoxanthin, lycopene and zeaxanthin. There was also no association between lutein and FVC or FEV1/FVC%. However, after stratification by smoking status, lutein intake was significantly associated with lower FEV1/FVC% in current smokers (-1·69 (95 % CI -2·93, -0·45) % per sd increase of lutein) independent of other carotenoids. The present study does not support an independent association between lutein intake and lung function in adults. However, future studies should focus on the potential inverse association between high lutein intake and lung function in specific risk groups such as smokers.

Dietary Antioxidants: Potential Anticancer Agents

There are several extrinsic and intrinsic factors involving reactive oxygen species that play critical roles in tumor development and progression by inducing DNA mutations, genomic instability, and aberrant pro-tumorigenic signaling. There are various essential micronutrients including minerals and vitamins in the diet, which play pivotal roles in maintaining and reinforcing antioxidant performance, affecting the complex network of genes (nutrigenomic approach) and encoding proteins for carcinogenesis. A lot of these antioxidant agents are available as dietary supplements and are predominant worldwide. However, the best antioxidant micronutrient (or a combination of micronutrients) for reducing cancer risks is unknown. The purpose of this review is to survey the literature on modern biological theories of cancer and the roles of dietary antioxidants in cancer. The roles and functions of antioxidant micronutrients, such as vitamin C (ascorbate), vitamin E (alpha-tocopherol), selenium, and vitamin A, provided through diet for the prevention of cancer are discussed in the present work.

The role of micronutrients in the response to ambient air pollutants: Potential mechanisms and suggestions for research design

People living in regions of low socioeconomic status are thought to be prone to higher exposures to environmental pollutants, poor nutrition, and numerous preventable diseases and infections. Poverty correlates with pollution and malnutrition; however, limited studies examined their interrelationship. The well-studied, deleterious health effects attributed to environmental pollutants and poor nutrition may act in combination with produce more severe adverse health outcomes than any one factor alone. Deficiencies in specific nutrients render the body more susceptible to injury which may influence the pathways that serve as the mechanistic responses to ambient air pollutants. This review (1) explores specific micronutrients that are of global concern, (2) explains how these nutrients may impact the body's response to ambient air pollution, and (3) provides guidance on designing animal models of nutritional deficiency. It is likely that those individuals who reside in regions of high ambient air pollution are similarly malnourished. Therefore, it is important that research identifies specific nutrients of concern and their impact in identified regions of high ambient air pollution.

Exogenous antioxidants--Double-edged swords in cellular redox state: Health beneficial effects at physiologic doses versus deleterious effects at high doses

The balance between oxidation and antioxidation is believed to be critical in maintaining healthy biological systems. Under physiological conditions, the human antioxidative defense system including e.g., superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and others, allows the elimination of excess reactive oxygen species (ROS) including, among others superoxide anions (O₂^.-), hydroxyl radicals (OH.), alkoxyl radicals (RO.) and peroxyradicals (ROO.). However, our endogenous antioxidant defense systems are incomplete without exogenous originating reducing compounds such as vitamin C, vitamin E, carotenoids and polyphenols, playing an essential role in many antioxidant mechanisms in living organisms. Therefore, there is continuous demand for exogenous antioxidants in order to prevent oxidative stress, representing a disequilibrium redox state in favor of oxidation. However, high doses of isolated compounds may be toxic, owing to prooxidative effects at high concentrations or their potential to react with beneficial concentrations of ROS normally present at physiological conditions that are required for optimal cellular functioning. This review aims to examine the double-edged effects of dietary originating antioxidants with a focus on the most abundant compounds, especially polyphenols, vitamin C, vitamin E and carotenoids. Different approaches to enrich our body with exogenous antioxidants such as via synthetic antioxidants, diets rich in fruits and vegetables and taking supplements will be reviewed and experimental and epidemiological evidences discussed, highlighting that antioxidants at physiological doses are generally safe, exhibiting interesting health beneficial effects.

Perspective: Randomized Controlled Trials Are Not a Panacea for Diet-Related Research

Research into the role of diet in health faces a number of methodologic challenges in the choice of study design, measurement methods, and analytic options. Heavier reliance on randomized controlled trial (RCT) designs is suggested as a way to solve these challenges. We present and discuss 7 inherent and practical considerations with special relevance to RCTs designed to study diet: 1) the need for narrow focus; 2) the choice of subjects and exposures; 3) blinding of the intervention; 4) perceived asymmetry of treatment in relation to need; 5) temporal relations between dietary exposures and putative outcomes; 6) strict adherence to the intervention protocol, despite potential clinical counter-indications; and 7) the need to maintain methodologic rigor, including measuring diet carefully and frequently. Alternatives, including observational studies and adaptive intervention designs, are presented and discussed. Given high noise-to-signal ratios interjected by using inaccurate assessment methods in studies with weak or inappropriate study designs (including RCTs), it is conceivable and indeed likely that effects of diet are underestimated. No matter which designs are used, studies will require continued improvement in the assessment of dietary intake. As technology continues to improve, there is potential for enhanced accuracy and reduced user burden of dietary assessments that are applicable to a wide variety of study designs, including RCTs.

Prognostic Significance of VEGF after Twenty-Year Follow-up in a Randomized Trial of Fenretinide in Non-Muscle-Invasive Bladder Cancer

Non-muscle-invasive bladder cancer (NMIBC) may progress to muscle-invasive disease, but no effective preventive treatments are available. In addition, no reliable prognostic biomarkers have been identified. We assessed the long-term effect of the oral retinoid fenretinide and the prognostic value of circulating VEGF levels. We updated through the Tumor Registry the vital status of 99 patients with resected Ta/T1 bladder tumors who were recruited in a randomized trial of 2 years of fenretinide or no treatment in 1993-1994. Serum VEGF levels measured at baseline and 12 months were available in a subgroup of 62 patients. After a median of 20.5 years, 54 subjects died, 35 of any cancer and 14 of bladder cancer. Neither overall survival (OS), nor cancer survival (CS) or bladder cancer survival (BCS) was affected by fenretinide (log-rank P ≥ 0.2). DNA aneuploidy in bladder washing was associated with shorter OS (P = 0.02), CS (P = 0.05), and BCS (P = 0.09). Subjects with baseline VEGF levels in the top quintile (≥350 pg/mL) had a significantly shorter OS (P = 0.01), CS (P = 0.02), and BCS (P = 0.008). The trend across quintiles of VEGF was significant for BCS (P = 0.007). Multivariate analyses showed that, in addition to smoking status, VEGF level in the top quintile was an independent prognostic factor for OS (HR = 2.7; 95% CI, 1.1-6.5), CS (HR = 3.3; 95% CI, 1.1-9.4) and BCS (HR = 8.9; 95% CI,1.3-61). Fenretinide did not affect the long-term outcome of patients with NMIBC. High serum VEGF level was a significant predictor of overall and cancer death and may help to identify high-risk subjects who may benefit from a preventive therapy. Cancer Prev Res; 9(6); 437-44. ©2016 AACR.

Mitochondrion-Permeable Antioxidants to Treat ROS-Burst-Mediated Acute Diseases

Reactive oxygen species (ROS) play a crucial role in the inflammatory response and cytokine outbreak, such as during virus infections, diabetes, cancer, cardiovascular diseases, and neurodegenerative diseases. Therefore, antioxidant is an important medicine to ROS-related diseases. For example, ascorbic acid (vitamin C, VC) was suggested as the candidate antioxidant to treat multiple diseases. However, long-term use of high-dose VC causes many side effects. In this review, we compare and analyze all kinds of mitochondrion-permeable antioxidants, including edaravone, idebenone, α-Lipoic acid, carotenoids, vitamin E, and coenzyme Q10, and mitochondria-targeted antioxidants MitoQ and SkQ and propose astaxanthin (a special carotenoid) to be the best antioxidant for ROS-burst-mediated acute diseases, like avian influenza infection and ischemia-reperfusion. Nevertheless, astaxanthins are so unstable that most of them are inactivated after oral administration. Therefore, astaxanthin injection is suggested hypothetically. The drawbacks of the antioxidants are also reviewed, which limit the use of antioxidants as coadjuvants in the treatment of ROS-associated disorders.