Association between dietary antioxidants intake and the risk of type 2 diabetes mellitus in a prospective cohort study: Tehran Lipid and Glucose Study

The present prospective cohort study aimed to determine whether dietary antioxidants were associated with incident type 2 diabetes mellitus (T2DM). Another objective was to find out whether such associations could be modified by the BMI status. A total of 2188 Tehranian adults aged 21-84 years, free of T2DM with the validated FFQ, was entered in the study. Multivariable Cox proportional hazards models adjusting for confounders were used to assess the association between dietary antioxidants and incident T2DM in total population, as well as in subjects with various BMI statuses. During 8·9 (8·1-9·6) years of follow-up, dietary vitamin E significantly decreased the incident T2DM, after adjustment for confounders. However, other dietary antioxidants were not shown to be significantly associated with incident T2DM. The interaction between dietary vitamin E, Mg and BMI status was found to influence the risk of T2DM (Pfor interaction < 0·05). After stratification of subjects based on BMI status, it was found that vitamin E and Mg decreased the risk of T2DM only among normal-weight individual. Also, an inverse association was found among dietary vitamin C, dietary Zn and the risk of T2DM in individuals with normal weight but not in overweight and obese individuals; however, the interaction test tended to be significant for these dietary variables. Dietary antioxidants including vitamin E, vitamin C, Zn and Mg when accompanied by healthy weight, may bring benefits to the prevention of T2DM.

The power of the QUENCHER method in measuring total antioxidant capacity of foods: Importance of interactions between different forms of antioxidants

Antioxidants play a crucial role in maintaining human health by counteracting oxidative stress and regulating redox balance within the body. The mixture of various antioxidant compounds in different forms (i.e., free, bound, insoluble) in food creates a redox active environment both in the human body and in the food system. Acting as both electron donors and acceptors while interacting with each other can either result in antagonism through pro-oxidative effects, or synergism through regeneration of one antioxidant by another. During the antioxidant capacity measurement, besides the individual antioxidant effects of the antioxidant components, these effects that occur because of their interaction with each other should be also considered. Classical antioxidant capacity measurement methods mostly concentrate on the fractions of foods that can be extracted with either water, alcohol, lipid, or acid/alkaline solutions. Antioxidants that cannot be extracted with any solvent are mostly ignored in these methods. On the other hand, the QUENCHER method, which allows direct measurement of antioxidant capacity foods without extraction, offers a rational solution to the limitations of traditional extraction-based methods. This approach considers the antioxidant capacity and interactions of all antioxidant forms that can be found in a food matrix, at the same time. This review provides detailed insights into the advantages of QUENCHER as a holistic approach for the accurate measurement of the antioxidant capacity of foods.

Dietary inflammatory index, dietary total antioxidant capacity, and frailty among older Chinese adults

OBJECTIVES

Frailty is an age-related syndrome associated with poor health outcomes. Studies in developed countries indicate that the dietary inflammatory index (DII) and dietary total antioxidant capacity (DTAC) are important dietary factors influencing the risk of frailty in older adults. However, few studies have explored the association between DII, DTAC, and frailty among older Chinese adults. The objective of the current study was to examine whether DII and DTAC were associated with pre-frailty or frailty among older Chinese adults.

DESIGN

A cross-sectional study.

SETTING

Community-based.

PARTICIPANTS

We included 6414 participants aged ≥60 years.

MEASUREMENTS

Dietary intake was assessed using a validated food frequency questionnaire (FFQ). The DII and energy-adjusted DII (E-DII) were calculated using food parameters. DTAC was estimated using two widely adopted antioxidant scores: DTAC based on ferric reducing antioxidant power and dietary antioxidant quality score (DAQS) obtained from vitamins (vitamins A, C, and E) and minerals (zinc and selenium) with antioxidant functions. Frailty was assessed using the frailty index (FI) calculated from 28 health-related deficits. Individuals were classified as robust (FI ≤ 0.10), pre-frailty (FI > 0.10 to <0.25), or frailty (FI ≥ 0.25). Multiple logistic regression models were used to evaluate the associations of DII and DTAC with pre-frailty and frailty.

RESULTS

After adjusting for confounding factors, individuals in the highest DII quintile (Q5) were more likely to have pre-frailty (odds ratio [OR] = 1.56; 95% confidence interval [CI]: 1.25-1.93; P for trend <0.001) than those in the lowest Q1. A similar positive association was detected for E-DII and pre-frailty. A significant association was found between DII and frailty. Compared with the lowest Q1, the highest Q5 of DTAC was negatively correlated with pre-frailty (OR = 0.66; 95% CI: 0.52-0.84; P for trend <0.001) and frailty (OR = 0.71; 95% CI: 0.50-0.1.03; P for trend <0.001). The DAQS yielded results similar to pre-frailty results (OR = 0.72; 95% CI: 0.58-0.89; P < 0.001). There was no evidence suggesting an association between DAQS and frailty.

CONCLUSIONS

More proinflammatory diets were linked to higher pre-frailty risk, whereas higher levels of dietary antioxidants were associated with lower pre-frailty and frailty risk among older Chinese adults.

Association between dietary antioxidants intake and childhood eczema: results from the NHANES database

BACKGROUND

High dietary intake of antioxidants reduces the risk of allergic sensitization in children. However, there was no sufficient evidence for the effect of dietary antioxidants intake on childhood eczema. Herein, this study aimed to explore the roles of different dietary antioxidants in childhood eczema.

METHODS

Data of 2305 children and adolescents aged < 18 years old were extracted from the National Health and Nutrition Examination Survey database in 2005-2006 in this cross-sectional study. The associations between dietary antioxidants intake and childhood eczema were explored using univariate and multivariate logistic regression analyses, with odds ratios (ORs) and confidence intervals (CIs). Subgroup analyses based on age and gender were also performed.

RESULTS

A total of 268 (11.6%) children had eczema. After adjusting for covariates, we found no significant associations between dietary intake of β-carotene, vitamin C, selenium (Se), and retinol and childhood eczema. However, compared with children and adolescents whose dietary zinc (Zn) intake < 7.47 mg, those who had dietary Zn intake level ≥ 11.83 mg seemed to have lower odds of eczema [OR 0.45, 95% CI 0.28-0.73]. In addition, subgroup analysis showed that especially in children and adolescents aged 1-11 years old, whatever the gender, a higher dietary intake level of Zn may benefit childhood eczema (all P < 0.05).

CONCLUSION

We concluded dietary Zn intake was negatively associated with childhood eczema. Further studies are needed to explore the roles of dietary antioxidants intake in childhood eczema.

Bone mineral density is associated with composite dietary antioxidant index among US adults: results from NHANES

This cross-sectional study investigated the relationship between composite dietary antioxidant index (CDAI) and individual dietary antioxidant intakes, including vitamins A, C, and E, zinc, selenium, and carotenoids, and bone mineral density (BMD) in the US population aged 20 years older. We found a positive correlation between CDAI and femoral BMD. Moreover, higher intakes of vitamin C, vitamin E, selenium, zinc, and carotenoids were associated with higher femoral BMD.

INTRODUCTION

While individual dietary antioxidants have shown beneficial effects on bone metabolism, the diverse and potentially interacting nature of dietary components may limit the accuracy of evaluating their impact on bone health. Thus, this study aims to investigate the association between CDAI and BMD. Additionally, we explore the relationship between the intake of individual components of the CDAI and BMD.

METHODS

The CDAI is a novel index evaluating total dietary antioxidant intake, considering vitamins A, C, and E, zinc, selenium, and carotenoids. A cross-sectional analysis was conducted using data from participants aged ≥ 20 in the National Health and Nutrition Examination Survey (2005-2010, 2013-2014, and 2017-2018). We utilized multivariate linear regression models to examine the relationship between CDAI, individual dietary antioxidants, including vitamins A, C, and E, zinc, selenium, carotenoids, and femoral BMD.

RESULTS

The final analysis included 10,584 participants with a mean age of 50.73 ± 16.65 years. After multivariate adjustment, the second to fourth quartiles of CDAI (- 2.00-0.04, 0.04-2.54, and 2.54-70.78) exhibited higher femoral BMD compared to the first quartile of CADI (- 7.34 to - 2.00). Multiple regression analysis revealed that higher intakes of vitamin C, vitamin E, selenium, zinc, and carotenoids were associated with higher femoral BMD.

CONCLUSIONS

CDAI serves as a comprehensive tool for evaluating the overall antioxidant capacity of antioxidants in diets. Additionally, our study shows a positive correlation between CDAI and BMD, which indicates that the combined intake of dietary antioxidants may help reduce the risk of osteoporosis in adults.

Dietary antioxidants and vascular calcification: From pharmacological mechanisms to challenges

Vascular calcification (VC), an actively regulated process, has been recognized as an independent and strong predictor of cardiovascular disease (CVD) and mortality worldwide. Diet has been shown to have a major role in the progression of VC. Oxidative stress (OS), a common pro-calcification factor, is closely related to VC, and evidence strongly suggests that dietary antioxidants directly prevent VC. Herein, we provided an overview of OS and its key role in VC and underlined the mechanisms of harmful effects of OS on VC. Furthermore, we introduced dietary antioxidants, and discussed about surrounding the challenges of dietary antioxidants in VC management. This review will benefit future research about the effects of dietary antioxidants on cardiovascular health.

Integument colouration and circulating carotenoids in relation to urbanisation in Eurasian kestrels (Falco tinnunculus)

Urbanisation is one of the biggest environmental challenges of our time, yet we still lack an integrative understanding of how cities affect behaviour, physiology and parasite susceptibility of free-living organisms. In this study, we focus on carotenoids, strictly dietary micronutrients that can either be used as yellow-red pigments, for integument colouration (signalling function), or as antioxidants, to strengthen the immune system (physiological function) in an urban predator, the Eurasian kestrel (Falco tinnunculus). Kestrels are specialised vole hunters but shift to avian prey in cities where diurnal rodents are not sufficiently available. This different foraging strategy might determine the quantity of carotenoids available. We measured integument colouration, circulating carotenoids in the blood and ectoparasite burden in kestrels along an urban gradient. Our results showed that nestlings that were raised in more urbanised areas displayed, unrelated to their ectoparasite burden, a paler integument colouration. Paler colours were furthermore associated with a lower concentration of circulating carotenoids. These findings support the hypothesis that the entire urban food web is carotenoid deprived and only prey of low quality with low carotenoid content is available (e.g. fewer carotenoids in urban trees, insects, small birds and finally kestrels). The alternative hypothesis that nestlings allocate carotenoids to reduce physiological stress and/or to cope with parasites rather than invest into colouration could not be supported. Our study adds to existing evidence that urban stressors negatively affect carotenoid production in urban areas, a deficiency that dissipate into higher trophic levels.

Association between an oxidative balance score and mortality: a prospective analysis in the SUN cohort

PURPOSE

We aimed to prospectively investigate the association of an overall oxidative balance score (OBS) with all-cause death and cause-specific mortality among participants in the Seguimiento Universidad de Navarra (SUN) Study, a Mediterranean cohort of Spanish graduates.

METHODS

Using baseline information on 12 a priori selected dietary and non-dietary lifestyle pro- and antioxidants exposures-vitamins C and E, β-carotenes, selenium, zinc, heme iron, polyphenols, total antioxidant capacity, body mass index, alcohol, smoking, and physical activity-we constructed an equally weighted OBS categorized into quartiles, with higher scores representing greater antioxidant balance. Cox proportional hazards models were fitted to evaluate the association between the OBS and mortality.

RESULTS

A total of 18,561 participants (mean [SD] age, 38.5 [12.4] years; 40.8% males) were included in the analysis. During a median follow-up of 12.2 years (interquartile range 8.3-14.9), 421 deaths were identified, including 80 deaths from cardiovascular disease (CVD), 215 from cancer, and 126 from other causes. After adjustment for potential confounders, the hazard ratios and 95% confidence interval (CIs) between the highest quartile (predominance of antioxidants) vs. the lowest quartile (reference category) were 0.35 (95% CI 0.22-0.54, P-trend < 0.001) for all-cause mortality, 0.18 (95% CI 0.06-0.51, P-trend = 0.001) for CVD mortality, 0.35 (95% CI 0.19-0.65, P-trend = 0.002) for cancer mortality, and 0.45 (95% CI 0.20-1.02, P-trend = 0.054) for other-cause mortality.

CONCLUSION

Our findings suggest a strong inverse association between the OBS and all-cause, CVD, and cancer mortality. Individuals exposed to both antioxidant dietary and lifestyle factors may potentially experience the lowest mortality risk.

STUDY REGISTRY NUMBER

Dynamic Mediterranean Prospective Cohort: the SUN Project; NCT02669602. https://clinicaltrials.gov/ct2/show/NCT02669602 . https://proyectosun.es.

Antioxidants in brain tumors: current therapeutic significance and future prospects

Brain cancer is regarded among the deadliest forms of cancer worldwide. The distinct tumor microenvironment and inherent characteristics of brain tumor cells virtually render them resistant to the majority of conventional and advanced therapies. Oxidative stress (OS) is a key disruptor of normal brain homeostasis and is involved in carcinogenesis of different forms of brain cancers. Thus, antioxidants may inhibit tumorigenesis by preventing OS induced by various oncogenic factors. Antioxidants are hypothesized to inhibit cancer initiation by endorsing DNA repair and suppressing cancer progression by creating an energy crisis for preneoplastic cells, resulting in antiproliferative effects. These effects are referred to as chemopreventive effects mediated by an antioxidant mechanism. In addition, antioxidants minimize chemotherapy-induced nonspecific organ toxicity and prolong survival. Antioxidants also support the prooxidant chemistry that demonstrate chemotherapeutic potential, particularly at high or pharmacological doses and trigger OS by promoting free radical production, which is essential for activating cell death pathways. A growing body of evidence also revealed the roles of exogenous antioxidants as adjuvants and their ability to reverse chemoresistance. In this review, we explain the influences of different exogenous and endogenous antioxidants on brain cancers with reference to their chemopreventive and chemotherapeutic roles. The role of antioxidants on metabolic reprogramming and their influence on downstream signaling events induced by tumor suppressor gene mutations are critically discussed. Finally, the review hypothesized that both pro- and antioxidant roles are involved in the anticancer mechanisms of the antioxidant molecules by killing neoplastic cells and inhibiting tumor recurrence followed by conventional cancer treatments. The requirements of pro- and antioxidant effects of exogenous antioxidants in brain tumor treatment under different conditions are critically discussed along with the reasons behind the conflicting outcomes in different reports. Finally, we also mention the influencing factors that regulate the pharmacology of the exogenous antioxidants in brain cancer treatment. In conclusion, to achieve consistent clinical outcomes with antioxidant treatments in brain cancers, rigorous mechanistic studies are required with respect to the types, forms, and stages of brain tumors. The concomitant treatment regimens also need adequate consideration.

Dietary antioxidant intake is inversely associated with 2,3-dinor oxylipin metabolites, the major excreted oxylipins in overweight and obese subjects

Cardiometabolic disease risk factors, including obesity, insulin resistance, high blood pressure, and dyslipidemia, are associated with elevated oxidative stress biomarkers like oxylipins. Increased adiposity by itself induces various isomers of this oxidized lipid family, while dietary polyphenols show benefits in its regulation. Previously, we showed that specific co-abundant microorganisms characterized the gut microbiota of Colombians and associated differentially with diet, lifestyle, obesity, and cardiometabolic health status, which led us to hypothesize that urinary oxylipins would reflect the intensity of oxidative metabolism linked to gut microbiota dysbiosis. Thus, we selected a convenience sample of 105 participants (age: 40.2 ± 11.9 years, 47.6% women), grouped according to microbiota, cardiometabolic health status, and body mass index (BMI); and evaluated 33 urinary oxylipins by HPLC-QqQ-MS/MS (e.g., isoprostanes, prostaglandins, and metabolites), paired with anthropometry and blood chemistry information and dietary antioxidants estimated from a 24-h food recall. In general, oxylipins did not show differences among individuals who differed in gut microbiota. While the unmetabolized oxylipin levels were not associated with BMI, the total content of oxylipin metabolites was highest in obese and cardiometabolically abnormal subjects (e.g., insulin resistant), mainly by prostaglandin-D (2,3-dinor-11β-PGF_2α) and 15-F_2t-IsoPs (2,3-dinor-15-F_2t-IsoP and 2,3-dinor-15-epi-15-F_2t-IsoP) metabolites. The total polyphenol intake in this cohort was 1070 ± 627 mg/day. After adjusting for body weight, the polyphenol intake was significantly higher in lean than overweight and showed an inverse association with dinor-oxylipin levels in principal component analysis. These results suggest that the 2,3-dinor-oxylipins could be more specific biomarkers associated with BMI than their parent oxylipins and that are sensitive to be regulated by dietary antioxidants.

Mitochondriotropic antioxidant based on caffeic acid AntiOxCIN4 activates Nrf2-dependent antioxidant defenses and quality control mechanisms to antagonize oxidative stress-induced cell damage

Mitochondria are key organelles involved in cellular survival, differentiation, and death induction. In this regard, mitochondrial morphology and/or function alterations are involved in stress-induced adaptive pathways, priming mitochondria for mitophagy or apoptosis induction. We have previously shown that the mitochondriotropic antioxidant AntiOxCIN₄ (100 μM; 48 h) presented significant cytoprotective effect without affecting the viability of human hepatoma-derived (HepG2) cells. Moreover, AntiOxCIN₄ (12.5 μM; 72 h) caused a mild increase of reactive oxygen species (ROS) levels without toxicity to primary human skin fibroblasts (PHSF). As Nrf2 is a master regulator of the oxidative stress response inducing antioxidant-encoding gene expression, we hypothesized that AntiOxCIN₄ could increase the resistance of human hepatoma-derived HepG2 to oxidative stress by Nrf2-dependent mechanisms, in a process mediated by mitochondrial ROS (mtROS). Here we showed that after an initial decrease in oxygen consumption paralleled by a moderate increase in superoxide anion levels, AntiOxCIN₄ led to a time-dependent Nrf2 translocation to the nucleus. This was followed later by a 1.5-fold increase in basal respiration and a 1.2-fold increase in extracellular acidification. AntiOxCIN₄ treatment enhanced mitochondrial quality by triggering the clearance of defective organelles by autophagy and/or mitophagy, coupled with increased mitochondrial biogenesis. AntiOxCIN₄ also up-regulated the cellular antioxidant defense system. AntiOxCIN₄ seems to have the ability to maintain hepatocyte redox homeostasis, regulating the electrophilic/nucleophilic tone, and preserve cellular physiological functions. The obtained data open a new avenue to explore the effects of AntiOxCIN₄ in the context of preserving hepatic mitochondrial function in disorders, such as NASH/NAFLD and type II diabetes.

Dietary supplements of vitamins E, C, and β-carotene to reduce oxidative stress in horses: An overview

Oxidative stress is the excess generation of free radicals and/or a decrease in the response of the antioxidant system. It is known to cause damage to the equine health by unbalancing the stable molecules. The supplements of vitamins E, C, and β-carotene in the diet cause beneficial effect on horses' health. These supplements could transform free radicals into the stable radicals, thereby showing importance in the prevention of diseases associated with oxidative stress. Adding vitamins E, C, and β-carotene to the horses' diets in stressful conditions could decrease the production of free radicals that cause inflammation and tissue damage, the typical characteristics that have been associated with oxidative stress. This review spotlights the available evidence of the benefits of dietary supplements of vitamins E, C, and β-carotene towards the reduction of oxidative stress in horses.

The association between dietary antioxidant index (DAI) and nonalcoholic fatty liver disease (NAFLD) onset; new findings from an incident case-control study

BACKGROUND

Evidence suggests an increasing global trend in non-alcoholic fatty liver disease (NAFLD) prevalence. Researchers have noted the importance of the role of dietary antioxidants in reducing the incidence of NAFLD. The dietary antioxidant index (DAI) is a valid indicator that considers the -diet's total antioxidant properties. The present study was designed and conducted to investigate the relationship between DAI and NAFLD. We hypothesized that there is a link between the DAI and the NAFLD.

METHODS

This case-control study included 295 patients with NAFLD and 704 controls. The patients' dietary intake was assessed through a valid and reliable semi-quantitative food frequency questionnaire. We standardized each of vitamin A, C, E, and selenium, manganese, and zinc by subtracting the global mean and dividing by the global SD to calculate the DAI.

RESULTS

Subjects with DAI score -0.46 < were at higher odds of having NAFLD compared to subjects with DAI -0.46 ≥ (OR_{DAI<-0.46/≥-0.46} = 0.55; 95% CI = 0.41-0.73). After adjustment for age, gender, and total energy intake (model B) a reverse and significant association was seen (OR_{DAI<-0.46/≥-0.46} = 0.57; 95% CI = 0.39-0.82).

CONCLUSION

The role of antioxidants in reducing the odds of NAFLD is fundamental. Taking antioxidants such as vitamins A, E, C, zinc, selenium, and manganese through food can effectively reduce NAFLD odds. On the other hand, studies should examine DAI's sensitivity and specificity in various settings and outcomes to use it in clinical work.

Dietary antioxidants and fibre intake and depressive symptoms in Iranian adolescent girls

OBJECTIVE

To investigate the cross-sectional association between dietary intakes of antioxidants and fibre and depressive symptoms among Iranian adolescent girls.

DESIGN

A cross-sectional population-based study.

SETTING

Primary schools in two different cities located in northeastern Iran (Mashhad and Sabzevar).

PARTICIPANTS

A total of 988 adolescent girls aged 12-18 years were included in the study.

RESULTS

Subjects with no or minimal depression symptoms had significantly higher dietary intakes of α-carotene (P = 0·01), β-carotene (P = 0·006), lutein (P = 0·03) and vitamin C (P = 0·04) when compared with subjects with mild-to-severe depression symptoms. Soluble dietary fibre and insoluble dietary fibre intakes were also significantly higher in healthy adolescents compared with those with depression symptoms (P < 0·001). In multivariate-adjusted model 2, the OR (95 % CI) of depressive symptoms were 0·61 (95 % CI 0·37, 1·01), 0·42 (95 % CI 0·26, 0·69), 0·50 (95 % CI 0·31, 0·79), 0·71 (95 % CI 0·44, 1·15), 0·51 (95 % CI 0·32, 0·82) and 0·42 (95 % CI 0·25, 0·68) for the highest v. lowest quartile of vitamin C, β-carotene, α-carotene, lutein, soluble dietary fibre and insoluble dietary fibre cereal intakes, respectively.

CONCLUSIONS

Dietary intake of some antioxidants and dietary fibre intake was inversely associated with depression symptoms among Iranian adolescent girls.

Association between serum β-carotene-to-retinol ratio and severity of hepatic steatosis in non-alcoholic fatty liver disease in Japan: A cross-sectional study

OBJECTIVES

Retinol and β-carotene have been reported to be involved in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, clinical studies are limited. The aim of this study was to investigate the relationship between serum the ratio of β-carotene to retinol (SC/SR) and hepatic steatosis in NAFLD diagnosed by ultrasonography.

METHODS

The participants were 606 Japanese adults who were enrolled in a health survey. Clinical profile, dietary nutrition intake, blood biochemistry, serum retinol, and carotenoids were analyzed. NAFLD was defined as fatty liver on ultrasonography in the absence of other causes of steatosis.

RESULTS

Women had higher daily intake of α- and β-carotene, although there were no differences in daily retinol and carotenoid intake between participants with or without NAFLD in both men and women. Women had a higher SC/SR ratio than men regardless of the presence or absence of NAFLD, and the SC/SR ratio in women decreased with exacerbation of hepatic steatosis, whereas the SC/SR ratio in men did not change despite exacerbation of hepatic steatosis. After adjusting for confounding factors, the likelihood of NAFLD among participants in the highest quartile of SC/SR ratio decreased by two-thirds compared with participants in the lowest quartile (adjusted odds ratio, 0.64; 95% confidence interval, 0.21-1.92; P = 0.041). The SC/SR ratio was positively correlated with serum high-density lipoprotein cholesterol level, and negatively correlated with serum triacylglycerol level.

CONCLUSIONS

The SC/SR ratio was lower in NAFLD with sex differences, and was associated with the severity of hepatic steatosis and lipid profile. Future studies are needed to expand on these findings.

Physiological relevance of food antioxidants

Dietary antioxidants are associated with prevention of oxidative stress related chronic diseases including certain types of cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases. In recent years, there has been a growing interest in extending the knowledge on their physiological effects in human body. There are numbers of epidemiological, clinical, meta-analysis, and in vitro studies to explain formation mechanisms of each chronic diseases as well as the potential effects of dietary antioxidants on these diseases and gut health. Comprehensive studies for food antioxidants' journey from dietary intake to target tissues/organs deserve a serious consideration to have a clear understanding on the physiological effects of dietary antioxidants. Therefore, absorption and metabolism of dietary antioxidants, and the factors affecting their absorption, such as solubility of antioxidants, food matrix, and interaction between antioxidants have been evaluated in several research articles. This chapter provides an overview about potential health effects of dietary antioxidants considering with their absorption and metabolism in human body.

Hydrophobic organic compounds in drinking water reservoirs: Toxic effects of chlorination and protective effects of dietary antioxidants against disinfection by-products

This study investigated formation and genotoxicities of disinfection by-products (DBPs) during chlorination of hydrophobic organic compounds (HOCs) extracted from six drinking water reservoirs around the Pearl River Delta region, China. Chemical analyses firstly showed that after chlorination aromatic HOCs (including polycyclic aromatic hydrocarbons, PAHs) decreased but DBPs (including chlorinated PAHs) increased, while genotoxicity assays revealed that the chlorination increased DNA damage in human Caco-2 cells. Although the link between DBPs and the genotoxicity was weak (insignificant correlations, p ≥ 0.05), we observed that chlorination of HOCs from more contaminated reservoirs in general resulted in higher genotoxicity. Secondly, remedial effects of catalase and dietary antioxidants (i.e. vitamin C and epigallocatechin gallate) in protecting cells against DBPs genotoxicity were detected. After 1 h treatment by the antioxidants, the DNA damage in Caco-2 cells (due to previous exposure to DBPs) significantly decreased (p < 0.05) in 7 out of a total of 18 treatments (38.9%). This is the first study demonstrating that catalase, vitamin C and epigallocatechin gallate protected human cells in vitro against DNA damage upon exposure to chlorinated genotoxic DBPs.

Flavonoids Ability to Disrupt Inflammation Mediated by Lipid and Cholesterol Oxidation

Flavonoids are plant secondary metabolites that act as protectants against harmful effects of UV-B radiation inasmuch as biotic stress, conferring at the same time pigmentation of fruits and leaves [67]. The term "flavonoid" refers to phenolics having a basic skeleton of diphenylpropane (C6-C3-C6), which consists of two aromatic rings linked through three carbons that usually form an oxygenated heterocycle [25, 52]. Flavonoids are broken down into several different sub-categories based on their chemical structure. The main subclasses commonly found in food items are: flavonols, flavones, flavanones, flavan-3-ols, proanthocyanidins, and anthocyanins [44, 67]. Figure 19.1 depicts the major classification of flavonoids according to their chemical structure. Their occurrence in food matrices has been extensively reviewed [39, 44], and has been subject of extensive research in the last decades. Table 19.1 contains a few examples of compounds from each of the subcategory, with the fruit (berry) in which they are commonly found. The monomeric unit of flavonoids can dimerize and polymerize to form other important high molecular weight molecules; this is the case of proanthocyanidins, that are polymers of flavan-3-ols or flavanols. Not only do these compounds act as plant protectants, but they can also be very beneficial to human health. Cohorts studies performed in the early '90 have shown that dietary consumption of flavonoids was inversely associated with morbidity and mortality from coronary heart disease [31, 32]. These findings have opened an intensive field of research on the effects of flavonoids and flavonoids-rich food extracts in cardiovascular diseases (CVD) progression, particularly in the modulating CVD-associated oxidative stress and inflammation. In this short review, we will summarize the current findings in flavonoids beneficial effects in preventing CVD through inhibition of initial stages of CVD progression. Given the magnitude of scientific literature in the field, we will focus on two strictly mechanistic aspects: inhibition of chemical-induced LDL oxidation, and the effect of flavonoids in the monocyte/macrophages activation pathways.

Association between dietary total antioxidant capacity and hepatocellular ballooning in nonalcoholic steatohepatitis: a cross-sectional study

PURPOSE

Nonalcoholic steatohepatitis (NASH) is characterized by steatosis, lobular inflammation, ballooning, and in some cases, fibrosis, which can progress to cirrhosis and carcinoma. The progression of NASH is closely related to oxidative stress. Dietary intake of antioxidants has been suggested in protection against oxidative damage and related clinical complications. Thus, we evaluated the potential association of dietary total antioxidant capacity (TAC) with disease severity in NASH patients, as well as with anthropometric and body composition markers and biochemical parameters.

METHODS

Thirty-three outpatients with a mean age of 48.4 ± 1.9 years were evaluated. Dietary TAC was estimated from a quantitative food frequency questionnaire. NASH severity, determined by liver biopsy, lifestyle characteristics, occurrence of comorbidities, anthropometry, body composition, and biochemical parameters were assessed.

RESULTS

NASH patients who had a higher dietary TAC had fewer ballooned hepatocytes compared to those with a lower TAC (p = 0.024). The patients with the highest dietary TAC had a reduction of approximately 20% in the risk of having many ballooned hepatocytes (OR 0.791; 95% CI 0.643-0.974; p = 0.027). There was no association of steatosis, lobular inflammation, and fibrosis with dietary TAC. The same occurred for lifestyle characteristics, occurrence of comorbidities, anthropometry, body composition, and biochemical parameters.

CONCLUSION

Dietary TAC is higher in patients with lower hepatic injury (ballooning), suggesting a possible role of food intake naturally high in its antioxidant capacity in reducing free radical production and, consequently, oxidative stress.

Environmental cues and dietary antioxidants affect breeding behavior and testosterone of male European starlings (Sturnus vulgaris)

Environmental cues, such as photoperiod, regulate the timing of major life-history events like breeding through direct neuroendocrine control. Less known is how supplementary environmental cues (e.g., nest sites, food availability) interact to influence key hormones and behaviors involved in reproduction, specifically in migratory species with gonadal recrudescence largely occurring at breeding sites. We investigated the behavioral and physiological responses of male European starlings to the sequential addition of nest boxes and nesting material, green herbs, and female conspecifics and how these responses depend on the availability of certain antioxidants (anthocyanins) in the diet. As expected, cloacal protuberance volume and plasma testosterone of males generally increased with photoperiod. More notably, testosterone levels peaked in males fed the high antioxidant diet when both nest box and herbal cues were present, while males fed the low antioxidant diet showed no or only a muted testosterone response to the sequential addition of these environmental cues; thus our results are in agreement with the oxidation handicap hypothesis. Males fed the high antioxidant diet maintained a constant frequency of breeding behaviors over time, whereas those fed the low antioxidant diet decreased breeding behaviors as environmental cues were sequentially added. Overall, sequential addition of the environmental cues modulated physiological and behavioral measures of reproductive condition, and dietary antioxidants were shown to be a key factor in affecting the degree of response to each of these cues. Our results highlight the importance of supplementary environmental cues and key resources such as dietary antioxidants in enhancing breeding condition of males, which conceivably aid in attraction of high quality females and reproductive success.

Effect of long-term dietary beta-carotene supplementation on sperm concentration and motility in an endangered amphibian

Dietary carotenoids have a high antioxidant capacity, so it has been hypothesised that carotenoid supplimentation will improve sperm production and quality by protecting sperm from oxidative damage. The effects of carotenoids on sperm have only been assessed in three vertebrate species, and evidence for improved sperm concentration and motility remains equivocal. One reason for this might be that in most studies there has not been an assessment of the effects of single carotenoid compounds over a range of doses. Applied research focused on developing ways to improve sperm quality could benefit the captive breeding and conservation of threatened species. The aim of the present study was to assess a dose-dependent effect of beta-carotene supplementation on sperm concentration and motility in the endangered booroolong frog (Litoria booroolongensis). Individuals were supplemented with one of four beta-carotene doses (0, 0.1, 1 and 10 mg/g) from hatching until sexual maturity (53 weeks). Sperm concentration was determined prior to activation, and percent sperm motility and sperm velocity were measured at 0, 3 and 6 h post-activation using computer-assisted sperm analysis. Unexpectedly, beta-carotene had no significant effect on sperm concentration, percent motility or velocity at any time point, providing no evidence for beneficial effects. Findings of the present study indicate there are likely to be species-specific differences in sperm production and motility that influence the risk of oxidative damage to sperm and dependence on dietary antioxidants to inhibit these detrimental effects.

Oxidative stress in inflammatory cells of patient with rheumatoid arthritis: clinical efficacy of dietary antioxidants

Rheumatoid arthritis (RA) is an autoimmune disease responsible for significant human morbidity in modern life. However, oxidative stress is one of the key markers for determining pathophysiology of patients with RA. The interaction between cellular immune system and body's endogenous and/or exogenous antigens produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) in autoimmune disease like RA. ROS and RNS include highly toxic superoxide (O₂^-) and peroxynitrite (ONOO^-) radicals, which activate the signaling cascades of inflammatory cells to synthesize pro-inflammatory cytokines and chemokines. Previous studies reported that Th1 cytokines could promote the development of autoimmune disorders like RA, whereas the Th2 cytokines may attenuate the same diseases. An increased awareness of the relationship between food and health led to a tremendous increase of antioxidant research in the last decade. Evaluation of the efficacy of dietary antioxidants is also becoming highly acceptable in RA research. A number of dietary phytomolecules are already established as having antioxidant activity in isolated synovial cellular infiltrate or peripheral blood neutrophils and lymphocytes. This review aims to highlight the oxidative stress in inflammatory cells of patients with RA and to summarize the clinical relevance of dietary antioxidants as a first step in assessing beneficial effect, safety and dose safety ratio in patients with RA.

Serum antioxidant capacity, biochemical profile and body composition of breast cancer survivors in a randomized Mediterranean dietary intervention study

PURPOSE

Increasing evidence suggests that Mediterranean Diet (MD) is correlated with reduced risk of breast cancer (BC) and cancer mortality, since it modifies patients' serum antioxidant capacity, body composition and biochemical parameters. The aim of the study was to investigate whether a dietary intervention based on MD has a beneficial effect on these factors.

METHODS

In this intervention study, seventy female BC survivors were randomly assigned to (1) the intervention group (personalized dietary intervention based on MD) and (2) the control group (received the updated American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention and ad libitum diet). Both groups were assessed twice [beginning, end of study (after 6 months)] regarding their anthropometric and biochemical parameters, serum vitamin C, vitamin A, a-tocopherol and CoQ10 levels, dietary intake and adherence to MD. An additional intermediate analysis was conducted on participants' body composition and biochemical profile.

RESULTS

Concerning the intervention group, body weight, body fat mass, waist circumference, body mass index as well as HDL-cholesterol were significantly decreased (P < 0.2%). An increase was observed in the vitamin C levels in blood (P < 0.2%). In the control group, body weight, body fat mass and serum total cholesterol rose (P < 0.2%). At the end of the study the two groups were significantly different considering blood glucose, vitamin C, polyunsaturated fatty acids, vitamin A and a-tocopherol levels.

CONCLUSIONS

This randomized dietary intervention based on MD managed to ameliorate serum antioxidant capacity, body composition, adherence to MD and glycemic profile of postmenopausal BC survivors.

Non-enzymatic antioxidant capacity (NEAC) estimated by two different dietary assessment methods and its relationship with NEAC plasma levels

PURPOSE

We aimed to quantify and compare dietary non-enzymatic antioxidant capacity (NEAC), estimated using two dietary assessment methods, and to explore its relationship with plasma NEAC.

METHODS

Fifty healthy subjects volunteer to participate in this study. Two dietary assessment methods [a food frequency questionnaire (FFQ) and a 24-hour recall (24-HR)] were used to collect dietary information. Dietary NEAC, including oxygen radical absorbance capacity (ORAC), total polyphenols, ferric-reducing antioxidant power (FRAP) and trolox equivalent antioxidant capacity, was estimated using several data sources of NEAC content in food. NEAC status was measured in fasting blood samples using the same assays. We performed nonparametric Spearman's correlation analysis between pairs of dietary NEAC (FFQ and 24-HR) and diet-plasma NEAC, with and without the contribution of coffee's NEAC. Partial correlation analysis was used to estimate correlations regardless of variables potentially influencing these relationships.

RESULTS

FFQ-based NEAC and 24-HR-based NEAC were moderately correlated, with correlation coefficients ranging from 0.54 to 0.71, after controlling for energy intake, age and sex. Statistically significant positive correlations were found for dietary FRAP, either derived from the FFQ or the 24-HR, with plasma FRAP (r ~ 0.30). This weak, albeit statistically significant, correlation for FRAP was mostly present in the fruits and vegetables food groups. Plasma ORAC without proteins and 24-HR-based total ORAC were also positively correlated (r = 0.35).

CONCLUSION

The relationship between dietary NEAC and plasma FRAP and ORAC suggests the dietary NEAC may reflect antioxidant status despite its weak in vivo potential, supporting further its use in oxidative stress-related disease epidemiology.

Associations between dietary antioxidants intake and radiographic knee osteoarthritis

The aim of the study is to examine the cross-sectional associations between dietary antioxidants (carotenoid, vitamin C, E, and selenium) intake and radiographic knee osteoarthritis (OA). A total of 4685 participants were included in this study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Radiographic knee OA was defined as Kellgren-Lawrence (K-L) grade 2 in at least one leg. A multivariable logistic analysis model was established to test the relationship between dietary antioxidants (carotenoid, vitamin C, E, and selenium) intake and radiographic knee OA with adjustment of a number of potential confounding factors. A significant positive association between dietary vitamin C intake (P value for trend was 0.04 in multivariable adjusted analysis) and radiographic knee OA was observed. The relative odds of radiographic knee OA were increased by 0.39 times in the third quintile (OR 1.39, 95 % CI 1.11-1.73), 0.42 times in the fourth quintile (OR 1.42, 95 % CI 1.13-1.79), and 0.33 times in the fifth quintile (OR 1.33, 95 % CI 1.03-1.71). However, radiographic knee OA was not significantly associated with dietary carotenoid, vitamin E, and selenium. Among dietary antioxidants, dietary vitamin C intake was positively correlated with the prevalence of radiographic knee OA, while no significant association was found between dietary intake of carotenoid, vitamin E, and selenium and the prevalence of radiographic knee OA.

Contribution of Macromolecular Antioxidants to Dietary Antioxidant Capacity: A Study in the Spanish Mediterranean Diet

Epidemiological and clinical studies show that diets with a high antioxidant capacity, such us those rich in plant food and beverages, are associated with significant decreases in the overall risk of cardiovascular disease or colorectal cancer. Current studies on dietary antioxidants and dietary antioxidant capacity focus exclusively on low molecular weight or soluble antioxidants (vitamins C and E, phenolic compounds and carotenoids), ignoring macromolecular antioxidants. These are polymeric phenolic compounds or polyphenols and carotenoids linked to plant food macromolecules that yield bioavailable metabolites by the action of the microbiota with significant effects either local and/or systemic after absorption. This study determined the antioxidant capacity of the Spanish Mediterranean diet including for the first time both soluble and macromolecular antioxidants. Antioxidant capacity and consumption data of the 54 most consumed plant foods and beverages were used. Results showed that macromolecular antioxidants are the major dietary antioxidants, contributing a 61% to the diet antioxidant capacity (8000 μmol Trolox, determined by ABTS method). The antioxidant capacity data for foods and beverages provided here may be used to estimate the dietary antioxidant capacity in different populations, where similar contributions of macromolecular antioxidants may be expected, and also to design antioxidant-rich diets. Including macromolecular antioxidants in mechanistic, intervention and observational studies on dietary antioxidants may contribute to a better understanding of the role of antioxidants in nutrition and health.

The proper time for antioxidant consumption

Consuming food rich in antioxidants may help organisms to increase their antioxidant defences and avoid oxidative damage. Under the hypothesis that organisms actively consume food for its antioxidant properties, they would need to do so in view of other physiological requirements, such as energy requirements. Here, we observed that Gouldian finches (Erythrura gouldiae) consumed most seeds rich in antioxidants in the middle of the day, while their consumption of staple seeds more profitable in energy intake (and poor in antioxidants) was maximal in the morning and the evening. This consumption of seeds rich in antioxidants in the middle of the day may be explicable (1) because birds took advantage of a time window associated with relaxed energy requirements to ingest antioxidant resources, or (2) because birds consumed antioxidant resources as a response to the highest antioxidant requirements in the middle of the day. If the latter hypothesis holds true, having the possibility to ingest antioxidants should be most beneficial in terms of oxidative balance in the middle of the day. Even though feeding on seeds rich in antioxidants improved Gouldian finches' overall antioxidant capacity, we did not detect any diurnal effect of antioxidant intake on plasma oxidative markers (as measured by the d-ROM and the OXY-adsorbent tests). This indicates that the diurnal pattern of antioxidant intake that we observed was most likely constrained by the high consumption of staple food to replenish or build up body reserves in the morning and in the evening, and not primarily determined by elevated antioxidant requirements in the middle of the day. Consequently, animals appear to have the possibility to increase antioxidant defences by selecting food rich in antioxidants, only when energetic constraints are relaxed.

Antioxidant therapy: still in search of the 'magic bullet'

The therapeutic potential of natural phenolic antioxidants in human diseases associated with oxidative damage has received great attention to date. Appraisal of literature evidences that, in general, antioxidant therapy has enjoyed relative successes in preclinical studies but little benefits in human intervention studies or clinical trials. In fact, despite the huge, largely untapped potential therapeutic benefit of natural phenolic antioxidants, such as vitamins, non-flavonoid and flavonoid compounds, they appear not to be suitable drug candidates. The problem may be related, among others, to their non-drug-likeness properties. Though controversial the results obtained so far confirm the importance of exploring phenolic natural systems as safe templates for the design of new antioxidants. To support the assumption an outlook of the lead structural optimization process to improve ADME properties was given by means of natural hydroxycinnamic acids as a case study. The optimization of drug physicochemical properties and the development of appropriate delivery antioxidant systems can provide in the next future a way out to attain effective therapeutic antioxidant agents.

Dietary antioxidents and oxidative stress in predialysis chronic kidney disease patients

CONTEXT

Dietary antioxidants are important in protecting against human diseases. Oxidative stress, a non- traditional risk factors of cardio-vascular disease is far more prevalent in chronic kidney disease (CKD) patients than in normal subjects.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Oxidative stress could be a consequence of an increase in reactive oxygen species as well as a decrease in antioxidant defenses. Among the important factors that can be involved in triggering oxidative stress is insufficient dietary intake of antioxidants. Malnourished CKD patients are reported to have more oxidative stress than well nourished ones.

CONCLUSIONS

Moving beyond the importance of assessment of dietary protein and energy in pre dialysis CKD patients to the assessment of dietary antioxidants is of utmost importance to help combat enhanced oxidative stress levels in such patients.

Diet in dermatology: present perspectives

Many nutrients are essential for life, and an adequate amount of nutrients in the diet is necessary for providing energy, building and maintaining body organs, and for various metabolic processes. The role of food in the induction of various skin disorders and skin diseases leading to nutritional deficiencies is well known. The photo-protective potential of antioxidants, the effects of micronutrient supplementation on the skin immune system, and the modulating effects of fatty acids on skin disorders are well documented. Skin diseases due to nutritional deficiencies, the dietary role in skin immunity and various skin diseases, and the role of antioxidants and other supplements in skin health have been reviewed.