Dietary antioxidants and cardiovascular disease

Vegetarian and vegan diets in type 2 diabetes management

Vegetarian and vegan diets offer significant benefits for diabetes management. In observational studies, individuals following vegetarian diets are about half as likely to develop diabetes, compared with non-vegetarians. In clinical trials in individuals with type 2 diabetes, low-fat vegan diets improve glycemic control to a greater extent than conventional diabetes diets. Although this effect is primarily attributable to greater weight loss, evidence also suggests that reduced intake of saturated fats and high-glycemic-index foods, increased intake of dietary fiber and vegetable protein, reduced intramyocellular lipid concentrations, and decreased iron stores mediate the influence of plant-based diets on glycemia. Vegetarian and vegan diets also improve plasma lipid concentrations and have been shown to reverse atherosclerosis progression. In clinical studies, the reported acceptability of vegetarian and vegan diets is comparable to other therapeutic regimens. The presently available literature indicates that vegetarian and vegan diets present potential advantages for the management of type 2 diabetes.

Nuts and novel biomarkers of cardiovascular disease

Nuts are energy-dense foods, rich in total fat and unsaturated fatty acids. The favorable fatty acid profile probably contributes to the beneficial effects of nut consumption observed in epidemiologic studies (prevention of coronary heart disease and diabetes) and feeding trials (cholesterol lowering). Besides fat, the complex matrices of nuts contain many bioactive compounds: vegetable protein, fiber, minerals, tocopherols, and phenolic compounds. By virtue of their unique composition, nuts are likely to benefit newer cardiovascular risk biomarkers, such as LDL oxidizability, soluble inflammatory molecules, and endothelial dysfunction. Protection of LDL oxidation by nut intake has been documented in some, but not all, clinical studies. In one study, feeding one daily serving of mixed nuts was associated with lower oxidized LDL concentrations. Regarding inflammation, cross-sectional studies have shown that nut consumption is associated with lower concentrations of circulating inflammatory molecules and higher plasma adiponectin, a potent antiinflammatory adipokine. Clinical studies with nuts have documented reduced inflammatory cytokine concentrations but no consistent changes of C-reactive protein. Only walnuts have been formally tested for effects on endothelial function. After both walnut diets and single walnut meals, favorable vasoreactivity changes have been observed. Walnut consumption also reduced expression of endothelin 1, a potent endothelial activator, in an animal model of accelerated atherosclerosis. Beneficial effects on vascular reactivity may be ascribed to several constituents of walnuts: l-arginine, the precursor of nitric oxide, alpha-linolenic acid, and phenolic antioxidants. Although more studies are warranted, the emerging picture is that nut consumption beneficially influences cardiovascular risk beyond cholesterol lowering.

Total antioxidant capacity of some commercial fruit juices: electrochemical and spectrophotometrical approaches

The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple DPPH· (2,2-diphenyl-1-picrylhydrazyl)/DPPH (2,2-diphenyl-1-picrylhydrazine). Trolox^® was chosen as a standard antioxidant. In the case of the spectrophometric method, the absorbance decrease of the DPPH· solution was followed. For the biamperometric method, the influence of some parameters like the potential diference, ΔE, DPPH· concentration, and Trolox^® concentration was investigated. The calibration graph obtained for Trolox^® presents linearity between 5 and 30 µM, (y = 0.059 x + 0.0564, where y represents the value of current intensity, expressed as μA and x the value of Trolox^® concentration, expressed as μM; r² = 0.9944). The R.S.D. value for the biamperometric method was 1.29% (n = 10, c = 15 μM Trolox^®). In the case of the spectrophotometric method, the calibration graph obtained for Trolox^® presents linearity between 0.01 and 0.125 mM (y = -9.5789 x+1.4533, where y represents the value of absorbance and x, the value of Trolox^® concentration, expressed as mM; r² = 0.9963). The R.S.D. value for the spectrophotometric method was 2.05%. Both methods were applied to total antioxidant activity determination in real samples (natural juices and soft drinks) and the results were in good agreement.

Use of conventional and -omics based methods for health claims of dietary antioxidants: a critical overview

This article describes the principles and limitations of methods used to investigate reactive oxygen species (ROS) protective properties of dietary constituents and is aimed at providing a better understanding of the requirements for science based health claims of antioxidant (AO) effects of foods. A number of currently used biochemical measurements aimed of determining the total antioxidant capacity and oxidised lipids and proteins are carried out under unphysiological conditions and are prone to artefact formation. Probably the most reliable approaches are measurements of isoprostanes as a parameter of lipid peroxidation and determination of oxidative DNA damage. Also the design of the experimental models has a strong impact on the reliability of AO studies: the common strategy is the identification of AO by in vitro screening with cell lines. This approach is based on the assumption that protection towards ROS is due to scavenging, but recent findings indicate that activation of transcription factors which regulate genes involved in antioxidant defence plays a key role in the mode of action of AO. These processes are not adequately represented in cell lines. Another shortcoming of in vitro experiments is that AO are metabolised in vivo and that most cell lines are lacking enzymes which catalyse these reactions. Compounds with large molecular configurations (chlorophylls, anthocyans and polyphenolics) are potent AO in vitro, but weak or no effects were observed in animal/human studies with realistic doses as they are poorly absorbed. The development of -omics approaches will improve the scientific basis for health claims. The evaluation of results from microarray and proteomics studies shows that it is not possible to establish a general signature of alterations of transcription and protein patterns by AO. However, it was shown that alterations of gene expression and protein levels caused by experimentally induced oxidative stress and ROS related diseases can be normalised by dietary AO.

Regulation of cellular signals from nutritional molecules: a specific role for phytochemicals, beyond antioxidant activity

Phytochemicals (PhC) are a ubiquitous class of plant secondary metabolites. A "recommended" human diet should warrant a high proportion of energy from fruits and vegetables, therefore providing, among other factors, a huge intake of PhC, in general considered "health promoting" by virtue of their antioxidant activity and positive modulation, either directly or indirectly, of the cellular and tissue redox balance. Diet acts through multiple pathways and the association between the consumption of specific food items and the risk of degenerative diseases is extremely complex. Recent literature suggests that molecules having a chemical structure compatible with a putative antioxidant capacity can actually "perform" activities and roles independent of such capacity, interacting with cellular functions at different levels, such as affecting enzyme activities, binding to membrane or nuclear receptors as either an elective ligand or a ligand mimic. Inductive or signaling effects may occur at concentrations much lower than that required for effective antioxidant activity. Therefore, the "antioxidant hypothesis" is to be considered in some cases an intellectual "shortcut" possibly biasing the real understanding of the molecular mechanisms underlying the beneficial effects of various classes of food items. In the past few years, many exciting new indications elucidating the mechanisms of polyphenols have been published. Here, we summarize the current knowledge of the mechanisms by which specific molecules of nutritional interest, and in particular polyphenols, play a role in cellular response and in preventing pathologies. In particular, their direct interaction with nuclear receptors and their ability to modulate the activity of key enzymes involved in cell signaling and antioxidant responses are presented and discussed.

Antioxidant, cytotoxic and genotoxic evaluation of alcoholic extract of Polyalthia cerasoides (Roxb.) Bedd

Antioxidative potential of alcohol extract of Polyalthia cerasoides was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical, superoxide anion scavenging, and reducing power assays were performed. The extract showed significant reactive oxygen species (ROS) scavenging activity in all in vitro antioxidant assays and contained high level of total phenolic content. For in vivo genotoxic evaluation, Swiss albino mice were treated with alcohol extract at the concentration of 40mg/kg body weight. Frequency of aberration was compared with control. Both the sets did not showed genotoxic effect. Further the extract was subjected to cytotoxic study using 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphynyl tetrazolium bromide (MTT) assay, the extract confirmed to show moderate cytotoxicity against L929 cell line.

Platelet receptor redox regulation

Several recent findings point to an important role for redox regulation of platelet responses to collagen involving the receptor, glycoprotein (GP)VI. First, the antioxidant dietary compound, quercetin, was shown to inhibit GPVI-dependent platelet activation and signaling responses to collagen. Second, collagen increased platelet production of the oxygen radical, superoxide anion (O2-), mediated by the multi-subunit enzyme nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidase. In that case, O2- was implicated in regulating not initial aggregation, but collagen-induced thrombus stabilization involving release of ADP. Third, our laboratory showed that an unpaired thiol in the GPVI cytoplasmic tail undergoes rapid oxidation to form GPVI homodimers following ligand binding, preceding GPVI signaling and ectodomain metalloproteolysis, and indicating formation of an oxidative submembranous environment in activated platelets. This review examines receptor/redox regulation in other cells, and relevance to the pathophysiological function of GPVI and other platelet receptors initiating thrombus formation in haemostasis or thrombotic diseases such as heart attack and stroke.

Health effects of quercetin: from antioxidant to nutraceutical

Quercetin, a member of the flavonoids family, is one of the most prominent dietary antioxidants. It is ubiquitously present in foods including vegetables, fruit, tea and wine as well as countless food supplements and is claimed to exert beneficial health effects. This includes protection against various diseases such as osteoporosis, certain forms of cancer, pulmonary and cardiovascular diseases but also against aging. Especially the ability of quercetin to scavenge highly reactive species such as peroxynitrite and the hydroxyl radical is suggested to be involved in these possible beneficial health effects. Consequently, numerous studies have been performed to gather scientific evidence for these beneficial health claims as well as data regarding the exact mechanism of action and possible toxicological aspects of this flavonoid. The purpose of this review is to evaluate these studies in order to elucidate the possible health-beneficial effects of the antioxidant quercetin. Firstly, the definitions as well as the most important aspects regarding free radicals, antioxidants and oxidative stress will be discussed as background information. Subsequently, the mechanism by which quercetin may operate as an antioxidant (tested in vitro) as well as the potential use of this antioxidant as a nutraceutical (tested both ex vivo and in vivo) will be discussed.

Consumption of fruit and berries is inversely associated with carotid atherosclerosis in elderly men

Epidemiological data suggest that fruit and vegetable consumption is associated with a lowered risk of CVD. We assessed the association between the intima-media thickness (IMT) of the carotid artery and dietary intake of vegetables, fruit and berries in elderly men with a high risk of CVD. Subjects (age 70 ±  5 years) were survivors from a cohort of 1232 men that participated in the Oslo Diet and Antismoking Study in 1972–3.Measurements of the carotid IMT by high resolution B-mode ultrasound, risk factor assessment and dietary data based on an FFQ were collected in 1997–9.Complete dietary and ultrasound data were available for 547 subjects. The carotid IMT in the highest quartile of dietary intake of fruit and berries was 0·89 (se 0·18) mm compared with 0·96 (se 0·25) mm in the lowest quartile, giving a mean difference of 0·075 (se 0·027) mm (P = 0·033). In multivariate regression analysis increased intake of fruit and berries remained inversely associated with IMT after adjustment for age, cigarette smoking, dietary cholesterol and saturated fat, consumption of milk, cream and ice cream and energy intake (multivariate regression coefficient 0·257; R2 0·066; se 0·209; P < 0·001). The difference of 348 g of fruit and berries per d between the lowest and highest quartile of intake was associated with a 5·5 % adjusted difference in mean IMT. These findings suggest that consumption of fruit and berries may be protective against carotid atherosclerosis in elderly men at high risk of CVD.

Risk factors for pregnancy-related mortality: a prospective study in rural Nepal

OBJECTIVES

This study examined the risk factors of mortality related to pregnancy for the first year post partum in a cohort of 25,580 pregnancies.

STUDY DESIGN

Longitudinal cohort follow-up.

METHODS

Details of socio-economic status, mid-upper arm circumference (MUAC), diet, illness, work, substance use and previous pregnancy history were collected during early to mid-gestation, and these women were followed for 1 year post partum. All-cause mortality rates per 100,000 pregnancies were calculated for deaths during pregnancy or up to 42 days post partum (early period) and 43-364 days post partum (late period). Odds ratios (OR) of mortality were estimated using five groups of risk factors: biological; morbidity; dietary; lifestyle; and socio-economic. Significant factors within each group were included in a single risk model for each time period.

RESULTS

Early and late pregnancy-related mortality rates were 469 [95% confidence interval (CI) 385-553] and 254 (95% CI 192-316), respectively. Maternal age > or = 35 years was associated with a three- to four-fold increase in mortality, whereas increasing parity conferred increasing protection. In the final model, a larger MUAC and consumption of dark green leaves were associated with decreased risk of death in the early period (OR 0.76, 95% CI 0.67-0.87 and 0.64, 95% CI 0.41-0.99, respectively). A larger MUAC was also associated with a lower risk of death in the late period. Diarrhoea/dysentery and pre-eclampsia were associated with increased risk of death in the early period (OR 2.78, 95% CI 1.40-5.51 and 2.95, 95% CI 1.48-5.90, respectively). Factors weakly associated (P<0.1) with mortality in both periods included night blindness, strenuous work activity and cigarette smoking. No socio-economic factors were significant in the models.

CONCLUSIONS

Maternal age, parity, MUAC, diet and illness in early to mid-gestation were associated with risk of death during pregnancy and the first year post partum in rural Nepal.

A randomized factorial trial of vitamins C and E and beta carotene in the secondary prevention of cardiovascular events in women: results from the Women's Antioxidant Cardiovascular Study

BACKGROUND

Randomized trials have largely failed to support an effect of antioxidant vitamins on the risk of cardiovascular disease (CVD). Few trials have examined interactions among antioxidants, and, to our knowledge, no previous trial has examined the individual effect of ascorbic acid (vitamin C) on CVD.

METHODS

The Women's Antioxidant Cardiovascular Study tested the effects of ascorbic acid (500 mg/d), vitamin E (600 IU every other day), and beta carotene (50 mg every other day) on the combined outcome of myocardial infarction, stroke, coronary revascularization, or CVD death among 8171 female health professionals at increased risk in a 2 x 2 x 2 factorial design. Participants were 40 years or older with a history of CVD or 3 or more CVD risk factors and were followed up for a mean duration of 9.4 years, from 1995-1996 to 2005.

RESULTS

A total of 1450 women experienced 1 or more CVD outcomes. There was no overall effect of ascorbic acid (relative risk [RR], 1.02; 95% CI, 0.92-1.13 [P = .71]), vitamin E (RR, 0.94; 95% CI, 0.85-1.04 [P = .23]), or beta carotene (RR, 1.02; 95% CI, 0.92-1.13 [P = .71]) on the primary combined end point or on the individual secondary outcomes of myocardial infarction, stroke, coronary revascularization, or CVD death. A marginally significant reduction in the primary outcome with active vitamin E was observed among the prespecified subgroup of women with prior CVD (RR, 0.89; 95% CI, 0.79-1.00 [P = .04]; P value for interaction, .07). There were no significant interactions between agents for the primary end point, but those randomized to both active ascorbic acid and vitamin E experienced fewer strokes (P value for interaction, .03).

CONCLUSION

There were no overall effects of ascorbic acid, vitamin E, or beta carotene on cardiovascular events among women at high risk for CVD.

Anthocyanins inhibit nuclear factor-kappaB activation in monocytes and reduce plasma concentrations of pro-inflammatory mediators in healthy adults

The transcription factor nuclear factor-kappaB (NF-kappaB) is activated by oxidative stress and pro-inflammatory stimuli and controls the expression of numerous genes involved in the inflammatory response. Dampening NF-kappaB activation and thereby limiting the inflammatory response have been suggested as a potential strategy to prevent chronic inflammatory diseases. In cultured monocytes, anthocyanins isolated from bilberries and black currants (Medox) efficiently suppressed LPS-induced activation of NF-kappaB. Furthermore, we studied the effect of anthocyanin supplementation (Medox, 300 mg/d for 3 wk) in a parallel-designed, placebo-controlled clinical trial (n = 120 men and women aged 40-74 y). Differences were observed in several NF-kappaB related inflammatory mediators in the Medox group compared to placebo. The changes in the NF-kappaB-controlled pro-inflammatory chemokines IL-8, "regulated upon activation, normal T cell expressed and secreted," (RANTES) and IFNalpha (an inducer of NF-kappaB activation) in the Medox group (45, 15, and 40% decreases from baseline, respectively) differed from those in the placebo group (20, 0, and 15% decreases from baseline, respectively) (P < 0.050). Similarly, changes in IL-4 and IL-13, 2 cytokines that mediate pro-inflammatory responses and induce NF-kappaB activation, in the Medox group (60 and 38% decreases from baseline, respectively) tended to differ from those in the placebo group (4 and 6% decreases) (P = 0.056 and, P = 0.089, respectively). These data suggest that anthocyanin supplementation may have a role in the prevention or treatment of chronic inflammatory diseases by inhibition of NF-kappaB transactivation and deceased plasma concentrations of pro-inflammatory chemokines, cytokines, and inflammatory mediators.

beta-Carotene and canthaxanthin alter the pro-oxidation and antioxidation balance in rats fed a high-cholesterol and high-fat diet

This study investigated the effects of beta-carotene and canthaxanthin on lipid peroxidation and antioxidative enzyme activities in rats fed a high-cholesterol, high-fat diet. Wistar rats were divided into six groups. Negative control group (group NC) received a high-fat (150 g/kg) diet; cholesterol control group (group CC) received a high-cholesterol (10 g/kg), high-fat diet. The other four groups were fed a high-cholesterol, high-fat diet supplemented with crystal beta-carotene (group BC), beta-carotene beadlet (group BB), canthaxanthin beadlet (group CX) or alpha-tocopherol (group AT). Blood and livers were collected for analysis after 6 weeks of feeding. Group BB had significantly lower hepatic thiobarbituric acid reactive substance (TBARS) and conjugated diene concentrations, whereas group CX had a significantly lower plasma TBARS concentration than did group CC. In erythrocytes, glutathione peroxidase activities were significantly greater in groups BC, BB and CX than in group CC. Moreover, compared with group CC, catalase activities were significantly greater in groups BB and CX, and superoxide dismutase (SOD) activity was significantly greater in group BB. In livers, SOD activities were significantly greater in groups BC, BB and CX, and glutathione reductase activities were significantly greater in groups BB and CX than in group CC. Compared with group CC, hepatic retinol and alpha-tocopherol concentrations were significantly greater in groups BC, BB and CX, whereas plasma and hepatic cholesterol concentrations were significantly lower in group BC. These findings suggest that beta-carotene and canthaxanthin altered the pro-oxidation and antioxidation balance and suppressed cholesterol-induced oxidative stress via modulation of antioxidant system and cholesterol metabolism.

Oxidative stress markers and antioxidant status after oral iron supplementation to very low birth weight infants

OBJECTIVE

To evaluate whether our current practice of giving iron 18 mg daily to 6-week-old infants with very low birth weight (VLBW) was associated with increased oxidative stress markers or decreased antioxidant status.

STUDY DESIGN

The study was a prospective observational study of 21 healthy VLBW infants (born at gestational age <32 weeks, birth weight <1500 g). Blood and urine were sampled twice before starting iron supplementation at 6 weeks postnatal age and after 1 week of iron supplementation at age 7 weeks. Urine 8-isoprostane was analyzed by gas chromatography-mass spectrometry and plasma total hydroperoxides were measured. Antioxidant status was assessed by ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), ferric-reducing ability of plasma, and plasma glutathione.

RESULTS

After 1 week of iron supplementation, no significant changes in urine 8-isoprostane or plasma total hydroperoxides were seen, and plasma antioxidants were largely unchanged.

CONCLUSIONS

Markers of oxidative stress in urine and plasma antioxidant status in healthy VLBW infants fed human milk remained unchanged after high-dose oral iron supplementation.

Health benefits of nuts: potential role of antioxidants

A diet rich in fruits, vegetables and minimally refined cereals is associated with lower risk for chronic degenerative diseases. Since oxidative stress is common in chronic degenerative disease, it has been assumed that dietary antioxidants may explain this protective effect. Every dietary plant contains numerous types of antioxidants with different properties. Many of these antioxidants cooperate in oxidative stress reduction in plants, and we hypothesize that many different antioxidants may also be needed for the proper protection of animal cells. To test this hypothesis, it is useful to identify dietary plants with high total antioxidant content. Several nuts are among the dietary plants with the highest content of total antioxidants. Of the tree nuts, walnuts, pecans and chestnuts have the highest contents of antioxidants. Walnuts contain more than 20 mmol antioxidants per 100 g, mostly in the walnut pellicles. Peanuts (a legume) also contribute significantly to dietary intake of antioxidants. These data are in accordance with our present extended analysis of an earlier report on nut intake and death attributed to various diseases in the Iowa Women's Health Study. We observed that the hazard ratio for total death rates showed a U-shaped association with nut/peanut butter consumption. Hazard ratio was 0.89 (CI = 0.81-0.97) and 0.81 (CI = 0.75-0.88) for nut/peanut butter intake once per week and 1-4 times per week, respectively. Death attributed to cardiovascular and coronary heart diseases showed strong and consistent reductions with increasing nut/peanut butter consumption. Further studies are needed to clarify whether antioxidants contribute to this apparent beneficial health effect of nuts.

Whole-grain consumption is associated with a reduced risk of noncardiovascular, noncancer death attributed to inflammatory diseases in the Iowa Women's Health Study

BACKGROUND

It has recently been shown that oxidative stress, infection, and inflammation are predominant pathophysiologic factors for several major diseases.

OBJECTIVE

We investigated the association of whole-grain intake with death attributed to noncardiovascular, noncancer inflammatory diseases.

DESIGN

Postmenopausal women (n = 41 836) aged 55-69 y at baseline in 1986 were followed for 17 y. After exclusions for cardiovascular disease, cancer, diabetes, colitis, and liver cirrhosis at baseline, 27 312 participants remained, of whom 5552 died during the 17 y. A proportional hazards regression model was adjusted for age, smoking, adiposity, education, physical activity, and other dietary factors.

RESULTS

Inflammation-related death was inversely associated with whole-grain intake. Compared with the hazard ratios in women who rarely or never ate whole-grain foods, the hazard ratio was 0.69 (95% CI: 0.57, 0.83) for those who consumed 4-7 servings/wk, 0.79 (0.66, 0.95) for 7.5-10.5 servings/wk, 0.64 (0.53, 0.79) for 11-18.5 servings/wk, and 0.66 (0.54, 0.81) for >or=19 servings/wk (P for trend = 0.01). Previously reported inverse associations of whole-grain intake with total and coronary heart disease mortality persisted after 17 y of follow-up.

CONCLUSIONS

The reduction in inflammatory mortality associated with habitual whole-grain intake was larger than that previously reported for coronary heart disease and diabetes. Because a variety of phytochemicals are found in whole grains that may directly or indirectly inhibit oxidative stress, and because oxidative stress is an inevitable consequence of inflammation, we suggest that oxidative stress reduction by constituents of whole grain is a likely mechanism for the protective effect.

Genetic and environmental contributions to serum ascorbic acid concentrations: the Stanislas Family Study

Although numerous environmental factors are documented to influence serum ascorbic concentrations, little is known about the genetic versus environmental contributions to variation of this trait. The aim of this study was to estimate family correlation and, additive genetic heritability and household effects in a variance component analysis for serum ascorbic acid concentrations. In a sample of ninety French families, information was obtained regarding serum ascorbic acid concentrations, usual dietary intake, lifestyle, and other related covariates. Spouse, parent–offspring and offspring–offspring significant correlation coefficients for serum ascorbic acid concentrations, adjusted for age, cigarette consumption and oral contraceptive use, were 0·432, 0·298 and 0·485, respectively, and for adjusted values for additional diet covariates (vitamin C intake and fruit and vegetable consumption), were 0·362, 0·154 and 0·348, respectively. Variance component analysis for serum ascorbic concentrations showed no significant genetic contribution to variability of this trait. Conversely, household common environment accounted for 27·7 and 42·6 % in parents and offspring, respectively, after adjustment for age, cigarette consumption and oral contraceptive use. After adjustment for the two additional diet covariates (vitamin C intake and fruit and vegetable consumption) household common variance decreased to 13·6 and 30·5 % in parents and offspring, respectively. These results show that serum ascorbic acid concentrations aggregate within healthy families partly due to diet intake but without a significant genetic component.

Effects of daily ingestion of chilli on serum lipoprotein oxidation in adult men and women

Laboratory studies have shown that the resistance of isolated LDL-cholesterol or linoleic acid to oxidation is increased in incubations with chilli extracts or capsaicin – the active ingredient of chilli. It is unknown if these in vitro antioxidative effects also occur in the serum of individuals eating chilli regularly. The present study investigated the effects of regular consumption of chilli on in vitro serum lipoprotein oxidation and total antioxidant status (TAS) in healthy adult men and women. In a randomised cross-over study, twenty-seven participants (thirteen men and fourteen women) ate ‘freshly chopped chilli’ blend (30g/d; 55% cayenne chilli) and no chilli (bland) diets, for 4 weeks each. Use of other spices, such as cinnamon, ginger, garlic and mustard, was restricted to minimum amounts. At the end of each dietary period serum samples were analysed for lipids, lipoproteins, TAS and Cu-induced lipoprotein oxidation. Lag time (before initiation of oxidation) and rate of oxidation (slope of propagation phase) were calculated. There was no difference in the serum lipid, lipoproteins and TAS at the end of the two dietary periods. In the whole group, the rate of oxidation was significantly lower (mean difference −0·23 absorbance ×10−3/min; P=0·04) after the chilli diet, compared with the bland diet. In women, lag time was higher (mean difference 9·61min; P<0·001) after the chilli diet, compared with the bland diet. In conclusion, regular consumption of chilli for 4 weeks increases the resistance of serum lipoproteins to oxidation.

Modulation of pregnane X receptor- and electrophile responsive element-mediated gene expression by dietary polyphenolic compounds

Based on animal models, dietary polyphenols are predicted to be promising chemopreventive agents in humans. Allspice, clove, and thyme extracts as well as defined dietary polyphenolic compounds were, therefore, tested for their ability to activate mechanisms related to phase 1 enzymes, i.e., the PXR-regulated CYP3A4 promoter, and phase 2 enzymes, i.e. the EpRE-regulated promoters of gastrointestinal glutathione peroxidase (GI-GPx) and heme oxygenase-1 (HO-1), examples of Nrf2-regulated genes. From the compounds tested, clove and thyme extracts as well as curcumin and resveratrol activated the PXR. PXR activation correlated with the activation of the CYP3A4 promoter in the case of thyme extract, curcumin, and resveratrol, but not in the case of clove extract. Allspice extract, EGCG, and quercetin did not activate PXR but enhanced CYP3A4 promoter activity. Thyme extract and quercetin activated the EpRE of HO-1. Both significantly activated the GI-GPx promoter, effects that depended on a functional EpRE. Resveratrol did not activate the isolated EpRE but enhanced the GI-GPx promoter activity, whereas clove extract even inhibited it. It is concluded that individual polyphenols as well as polyphenol-rich plant extracts may affect phase 1 and 2 enzyme expression by distinct mechanisms that must be elucidated, before potential health effects can reliably be predicted.

HYPERTENSION AND OXIDATIVE STRESS

1. Oxidative stress has been suggested to be involved in the pathogenesis of hypertension. This may be via a number of possible mechanisms, including quenching of the important vasodilator nitric oxide. 2. Animal studies have generally supported the hypothesis that increased blood pressure is associated with increased oxidative stress. However, human studies have been inconsistent and may differ owing to the populations studied and the various methods used. Treatment with anti-oxidants has been suggested to lower oxidative stress and, therefore, blood pressure. However, to date, studies investigating single or combination supplements have failed to show any consistent benefit. 3. Overall, the evidence supporting the link between hypertension and oxidative stress remains inconclusive, with methodological and population differences possibly confounding results. Further studies investigating this relationship are warranted.

Content of redox-active compounds (ie, antioxidants) in foods consumed in the United States

BACKGROUND

Supplements containing ascorbic acid, alpha-tocopherol, or beta-carotene do not protect against oxidative stress-related diseases in most randomized intervention trials. We suggest that other redox-active phytochemicals may be more effective and that a combination of different redox-active compounds (ie, antioxidants or reductants) may be needed for proper protection against oxidative damage.

OBJECTIVE

We aimed to generate a ranked food table with values for total content of redox-active compounds to test this alternative antioxidant hypothesis.

DESIGN

An assay that measures the total concentration of redox-active compounds above a certain cutoff reduction potential was used to analyze 1113 food samples obtained from the US Department of Agriculture National Food and Nutrient Analysis Program.

RESULTS

Large variations in the content of antioxidants were observed in different foods and food categories. The food groups spices and herbs, nuts and seeds, berries, and fruit and vegetables all contained foods with very high antioxidant contents. Most food categories also contained products almost devoid of antioxidants. Of the 50 food products highest in antioxidant concentrations, 13 were spices, 8 were in the fruit and vegetables category, 5 were berries, 5 were chocolate-based, 5 were breakfast cereals, and 4 were nuts or seeds. On the basis of typical serving sizes, blackberries, walnuts, strawberries, artichokes, cranberries, brewed coffee, raspberries, pecans, blueberries, ground cloves, grape juice, and unsweetened baking chocolate were at the top of the ranked list.

CONCLUSION

This ranked antioxidant food table provides a useful tool for investigations into the possible health benefit of dietary antioxidants.

Dose-dependent influence of commercial garlic (Allium sativum) on rats fed cholesterol-containing diet

The aim of this investigation was to evaluate the dose-dependent influence of commercial garlic on rats fed cholesterol-containing diets. It was found that commercial garlic contains high concentrations of dietary fibers, microelements, and total polyphenols, and its total antioxidant capacity as determined by two independent assays [1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS)] was similar to that of the original garlic samples. Wistar rats (35) were randomly divided into five diet groups, named control, Chol, Garlic500, Garlic750, and Garlic1000. Control rats were fed basal diet (BD), which included wheat starch, casein, soybean oil, and vitamin and mineral mixtures. To the BD of the Chol group was added 1% of cholesterol. To the BD of the other three groups (Garlic500, Garlic750, and Garlic1000) were added 1% of cholesterol and commercial garlic equal to 500, 750, and 1000 mg of raw garlic per kilogram of animal weight. After 4 weeks of the experiment only in rats from the Garlic500 group were a significant hindering in the rise in plasma lipids and also a significant hindering in a decrease of plasma antioxidant activity registered. A significant decrease in plasma circulating fibrinogen and an increase in the clotting time were found in the same group of rats (P < 0.05 in both cases). The fibrinogenolytic effect of garlic diets was visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the fibrinogen fraction of Garlic500 the 66, 24, and 14 kDa protein bands were detected with weaker protein intensity than in the corresponding ones in the Garlic750 and Garlic1000 diet groups. In conclusion, the positive influences of commercial garlic on plasma lipids, proteins, antioxidant activity, and some indices of blood coagulation are dose-dependent. Therefore, commercial garlic (Elena, Zelazków, Poland) could be a valuable component of atherosclerosis-preventing diets only in optimal doses.

Comparative study of natural antioxidants - curcumin, resveratrol and melatonin - in cadmium-induced oxidative damage in mice

The present study was designed to examine the antioxidative effect of curcumin, resveratrol and melatonin pre-treatment on cadmium-induced oxidative damage and cadmium distribution in an experimental model in mice. Male CD mice were treated once daily for 3 days with curcumin (50mg/kg b.w., p.o.), resveratrol (20mg/kg b.w., p.o.) or melatonin (12mg/kg, p.o.), dispersed in 0.5% methylcellulose. One hour after the last dose of antioxidants cadmium chloride was administered (7mg/kg b.w., s.c.) to pre-treated animals and control animals receiving methylcellulose. At 24th h after Cd administration the lipid peroxidation (LP - expressed as malondialdehyde production), reduced glutathione (GSH), catalase (CAT) and glutathione peroxidase (GPx) were estimated in liver homogenates. Cadmium concentration was measured in the liver, kidneys, testes and brain by AAS. Cadmium chloride administration to mice induced hepatic lipid peroxidation (to 133%, p<0.001), decreased GSH content (to 65%, p<0.001) and inhibited catalase (to 68%, p<0.001) and GPx activity (to 60%, p<0.001) in the liver. Curcumin, resveratrol and melatonin oral pre-treatment completely prevented the Cd-induced lipid peroxidation and Cd-induced inhibition of GPx hepatic activity. Resveratrol was effective against Cd-induced inhibition of catalase activity (p<0.001). The decrease in hepatic GSH level was not prevented by curcumin, resveratrol or melatonin pre-treatment. In mice treated with antioxidants alone the level of LP, GSH, GPx or CAT was not different from control levels. The pre-treatment with antioxidants did not affect cadmium distribution in the tissues of Cd-intoxicated mice. The results demonstrate that curcumin, resveratrol and melatonin pre-treatment effectively protect against cadmium-induced lipid peroxidation and ameliorate the adverse effect of cadmium on antioxidant status without any reduction in tissue Cd burden.

Consumption of coffee is associated with reduced risk of death attributed to inflammatory and cardiovascular diseases in the Iowa Women's Health Study

BACKGROUND

Coffee is the major source of dietary antioxidants. The association between coffee consumption and risk of death from diseases associated with inflammatory or oxidative stress has not been studied.

OBJECTIVE

We studied the relation of coffee drinking with total mortality and mortality attributed to cardiovascular disease, cancer, and other diseases with a major inflammatory component.

DESIGN

A total of 41,836 postmenopausal women aged 55-69 y at baseline were followed for 15 y. After exclusions for cardiovascular disease, cancer, diabetes, colitis, and liver cirrhosis at baseline, 27,312 participants remained, resulting in 410,235 person-years of follow-up and 4265 deaths. The major outcome measure was disease-specific mortality.

RESULTS

In the fully adjusted model, similar to the relation of coffee intake to total mortality, the hazard ratio of death attributed to cardiovascular disease was 0.76 (95% CI: 0.64, 0.91) for consumption of 1-3 cups/d, 0.81 (95% CI: 0.66, 0.99) for 4-5 cups/d, and 0.87 (95% CI: 0.69, 1.09) for > or =6 cups/d. The hazard ratio for death from other inflammatory diseases was 0.72 (95% CI: 0.55, 0.93) for consumption of 1-3 cups/d, 0.67 (95% CI: 0.50, 0.90) for 4-5 cups/d, and 0.68 (95% CI: 0.49, 0.94) for > or =6 cups/d.

CONCLUSIONS

Consumption of coffee, a major source of dietary antioxidants, may inhibit inflammation and thereby reduce the risk of cardiovascular and other inflammatory diseases in postmenopausal women.

Effects of pistachio nuts consumption on plasma lipid profile and oxidative status in healthy volunteers

BACKGROUND AND AIM

Effects of pistachio nuts consumption on plasma lipid profile and oxidative status were investigated in healthy volunteers with normal lipid levels.

METHODS AND RESULTS

The study was conducted in 24 healthy men and 20 healthy women. All subjects consumed their regular diets during a 1-week period. After this period, half of the subjects (12 men and 10 women, mean age 32.8 +/- 6.7 years) were randomized to a regular diet group and the other half (12 men and 10 women, mean age 33.4 +/- 7.2 years) were randomized to a pistachio group which involved substituting pistachio nuts for 20% of their daily caloric intake for 3 weeks. Plasma total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride, malondialdehyde (MDA) and antioxidant potential (AOP) were measured before and after the dietary modification from all the subjects. After 3 weeks, with the pistachio diet, the mean plasma total cholesterol, MDA levels and, total cholesterol/HDL and LDL/HDL ratios were found to be significantly decreased (P < 0.05, P < 0.05, P < 0.001 and P < 0.01, respectively); on the contrary, HDL and AOP levels, and AOP/MDA ratios were significantly increased (P < 0.001, P < 0.05 and P < 0.01, respectively). Triglyceride and LDL levels also decreased but this was not statistically significant (P > 0.05).

CONCLUSION

These results indicated that consumption of pistachio nuts decreased oxidative stress, and improved total cholesterol and HDL levels in healthy volunteers.

The antioxidative power AP--A new quantitative time dependent (2D) parameter for the determination of the antioxidant capacity and reactivity of different plants

In the last decade, naturally occurring antioxidants continue to play an important role in the food-supplement industry. The content of antioxidants in a plant depends on the species, temperature, humidity, period of growth, harvest month, part of the plant used and many other variables. Herein, we present a new method able to determine the all over antioxidative power (AP) of plant extracts or lyophilised plant parts based on the reducing activity against a stable test radical. The method is performed by ESR spectroscopy and is based on the well-known 1,1-diphenyl-2-picryl-hydrazil (DPPH) method with the major difference that both the antioxidative capacity and the antioxidative activity are used to characterise an antioxidant. The resulting antioxidative power is expressed in antioxidative units (AU), where 1AU corresponds to the activity of a 1 ppm solution of Vitamin C as a benchmark. This method allows a rapid, unexpensive and general applicable technique for the measurement of the antioxidative power of very different kinds of substances. The inclusion of the kinetic behaviour of the reducing process of the antioxidant for the determination of the AP allows the identification of the main antioxidant present in a sample. Herein, we present the application example of seeds, sprouts and adult parts of dandelion, amaranth, quinoa, fenugreek, broccoli, red clover and mugwort, where the AP method permits to characterise the plants with the highest antioxidant capacity and reaction velocity. The method permits to select active plant extracts for the food and nutrition industry.

Astaxanthin, a carotenoid with potential in human health and nutrition

Astaxanthin (1), a red-orange carotenoid pigment, is a powerful biological antioxidant that occurs naturally in a wide variety of living organisms. The potent antioxidant property of 1 has been implicated in its various biological activities demonstrated in both experimental animals and clinical studies. Compound 1 has considerable potential and promising applications in human health and nutrition. In this review, the recent scientific literature (from 2002 to 2005) is covered on the most significant activities of 1, including its antioxidative and anti-inflammatory properties, its effects on cancer, diabetes, the immune system, and ocular health, and other related aspects. We also discuss the green microalga Haematococcus pluvialis, the richest source of natural 1, and its utilization in the promotion of human health, including the antihypertensive and neuroprotective potentials of 1, emphasizing our experimental data on the effects of dietary astaxanthin on blood pressure, stroke, and vascular dementia in animal models, is described.

Dietary approaches that delay age-related diseases

Reducing food intake in lower animals such as the rat decreases body weight, retards many aging processes, delays the onset of most diseases of old age, and prolongs life. A number of clinical trials of food restriction in healthy adult human subjects running over 2-15 years show significant reductions in body weight, blood cholesterol, blood glucose, and blood pressure, which are risk factors for the development of cardiovascular disease and diabetes. Lifestyle interventions that lower energy balance by reducing body weight such as physical exercise can also delay the development of diabetes and cardiovascular disease. In general, clinical trials are suggesting that diets high in calories or fat along with overweight are associated with increased risk for cardiovascular disease, type 2 diabetes, some cancers, and dementia. There is a growing literature indicating that specific dietary constituents are able to influence the development of age-related diseases, including certain fats (trans fatty acids, saturated, and polyunsaturated fats) and cholesterol for cardiovascular disease, glycemic index and fiber for diabetes, fruits and vegetables for cardiovascular disease, and calcium and vitamin D for osteoporosis and bone fracture. In addition, there are dietary compounds from different functional foods, herbs, and neutraceuticals such as ginseng, nuts, grains, and polyphenols that may affect the development of age-related diseases. Long-term prospective clinical trials will be needed to confirm these diet-disease relationships. On the basis of current research, the best diet to delay age-related disease onset is one low in calories and saturated fat and high in wholegrain cereals, legumes, fruits and vegetables, and which maintains a lean body weight. Such a diet should become a key component of healthy aging, delaying age-related diseases and perhaps intervening in the aging process itself. Furthermore, there are studies suggesting that nutrition in childhood and even in the fetus may influence the later development of aging diseases and lifespan.

Adherence to the Mediterranean diet is associated with total antioxidant capacity in healthy adults: the ATTICA study

BACKGROUND

Greater adherence to the Mediterranean diet has been associated with a lower incidence of cardiovascular disease and cancer.

OBJECTIVE

We studied the effect of the Mediterranean diet on total antioxidant capacity (TAC) in 3042 participants who had no clinical evidence of cardiovascular disease.

DESIGN

During 2001-2002, a random sample of 1514 men and 1528 women aged 18-89 y from the Attica area of Greece was selected. TAC was measured with an immune-diagnostic assay. Food consumption was evaluated with a validated food-frequency questionnaire, and adherence to the Mediterranean diet was assessed on the basis of a diet score that incorporated the inherent characteristics of this diet.

RESULTS

TAC was positively correlated with diet score. The participants in the highest tertile of the diet score had, on average, 11% higher TAC levels than did the participants in the lowest tertile, even after adjustment for relevant confounders (P < 0.01). On the other hand, the participants in the highest tertile of the diet score had, on average, 19% lower oxidized LDL-cholesterol concentrations than did the participants in the lowest tertile (P < 0.01). An additional analysis showed that TAC was positively correlated with the consumption of olive oil (rho = 0.54, P = 0.002) and of fruit and vegetables (rho = 0.34 and rho = 0.31, respectively; P < 0.001 for both), whereas it was inversely associated with the consumption of red meat (rho = -0.35, P = 0.02).

CONCLUSION

Greater adherence to the Mediterranean diet is associated with elevated TAC levels and low oxidized LDL-cholesterol concentrations, which may explain the beneficial role of this diet on the cardiovascular system.

Iron-ascorbic acid-induced oxidant stress and its quenching by paraoxonase 1 in HDL and the liver: Comparison between humans and rats

Paraoxonase 1 (PON1) is a serum enzyme closely associated with high-density lipoprotein (HDL), which may protect against atherosclerosis by hydrolyzing lipid peroxides and several organophosphorus compounds. The purpose of the present study was to test the hypothesis that lipid peroxidation modifies the activity and protein mass of PON1 in humans and rats. Our findings revealed that the bulk of the activity monitored by the hydrolysis of paraoxon and phenyl acetate was confined to liver intracellular endoplasmic reticulum-derived microsomes and was mostly recovered in circulating HDL3. Confirmation was obtained by the determination of PON1 expression by Western blot. It is noteworthy that PON1 levels were consistently decreased in human sera, HDL, and liver microsomes compared with rat counterparts. Concomitant with iron-ascorbate-mediated lipid peroxidation, there was a decline in PON1 activity and protein in both HDL3 and microsomes, which was attenuated by butylated hydroxytoluene antioxidant treatment. The current data indicate that PON1 localization in microsomes and HDL3 could represent a selective cellular and lipoprotein response to oxidative stress. This was tested by the iron-ascorbate oxygen-radical generating system. It is also proposed that the increased PON1 level may have a function related to the well-known atherosclerosis resistance of rats.