Impact of short-term bilberry supplementation on glycemic control, cardiovascular disease risk factors, and antioxidant status in Chinese patients with type 2 diabetes.

Bilberry (Vaccinium myrtillus L.) is one of the richest natural sources of anthocyanins which are powerful antioxidants and reported to have antiinflammatory, antidyslipidemic, antihypertensive, and hypoglycemic effects. The objective of this study was to assess the effect of bilberry supplementation on biomarkers of glycemic control, lipid profile, antioxidant, and inflammatory status in patients with type 2 diabetes in a randomized, double-blind, placebo-controlled cross-over study. Twenty patients were randomized to receive either bilberry supplementation (1.4 g/day of extract) daily for 4 weeks followed by 6 weeks of washout and then an additional 4 weeks of matching placebo or vice versa. Blood pressure, metabolic parameters, antioxidant status, and oxidative stress were measured before and after each period. Results showed no effect on body weight, blood pressure, or lipid profile. HbA1c was reduced by 0.31 ± 0.58% during bilberry supplementation, but this change was not significantly different from that with placebo. Antioxidant status, oxidative stress, and inflammatory status showed no significant differences across treatments. This short-term study of bilberry supplementation did not show significant effects on cardiovascular risk factors or antioxidant status, but the tendency for improved glycemic control may suggest a longer treatment period may be effective in diabetic patients.

Vitamin D deficiency, oxidative stress and antioxidant status: only weak association seen in the absence of advanced age, obesity or pre-existing disease.

Vitamin D deficiency (plasma 25-hydroxycholecalciferol (25(OH)D)70 % of participants were vitamin D deficient. No significant correlations and no biomarker differences across 25(OH)D quartiles or groups were seen except for total antioxidant status. A weak direct association (r 0·252, P<0·05) was observed between 25(OH)D and FRAP, and those in the lowest 25(OH)D quartile and group had significantly lower FRAP values. Results did not reveal a clear link between vitamin D status and oxidative stress biomarkers in the absence of advanced age, obesity and disease, though some evidence of depleted antioxidant status in those with vitamin D deficiency was seen. Poor antioxidant status may pre-date increased oxidative stress. Study of effects of correction of deficiency on antioxidant status and oxidative stress in vitamin D-deficient but otherwise healthy subjects is needed.

Vitamin D and oxidation-induced DNA damage: is there a connection?

Oxidation-induced damage to DNA can cause mutations, phenotypic changes and apoptosis. Agents that oppose such damage offer potential therapies for disease prevention. Vitamin D administration reportedly lowered DNA damage in type 2 diabetic mice, and higher DNA damage was reported in mononuclear cells of severely asthmatic patients who were vitamin D deficient. We hypothesised that lower vitamin D status associates with higher oxidation-induced DNA damage. Vitamin D deficiency (plasma 25(OH)D < 50 nmol/l) is highly prevalent worldwide, and association with DNA damage has high potential importance and impact in regard to the future health of vitamin D deficient young adults. In this study, oxidation-induced DNA damage in peripheral lymphocytes of 121 young (18-26 years) adults was measured using the formamidopyrimidine DNA glycosylase (FPG)-assisted comet assay. Plasma 25(OH)D was measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Correlational analysis was performed between 25(OH)D and DNA damage. Differences in DNA damage across tertiles of 25(OH)D were explored using analysis of variance. DNA damage in those with 25(OH)D <50 nmol and ≥50 nmol/l was compared using the unpaired t-test. Mean (SD) DNA damage (as %DNA in comet tail) and plasma 25(OH)D were, respectively, 18.58 (3.39)% and 44.7 (13.03) nmol/l. Most (82/121; 68%) of the subjects were deficient in vitamin D (25(OH)D <50nmol/l). No significant correlation was seen between 25(OH)D and DNA damage (r = -0.0824; P > 0.05). No significant difference was seen across 25(OH)D tertiles: mean (SD) %DNA in comet tail/25(OH)D nmol/l values in lowest, middle and highest tertiles were, respectively, 18.64 (3.30)/31.6 (4.4), 18.90 (3.98)/42.9 (3.5), 18.19 (2.84)/59.9 (8.5), nor across the binary divide: 18.73 (3.63)% in <50nmol/l group vs. 18.27 (2.84)% in the ≥50 nmol/l group. No association between vitamin D and oxidation-induced DNA damage was observed, but vitamin D deficiency was highly prevalent in the young adults studied, and we cannot rule out an ameliorative effect of correction of vitamin D deficiency on DNA damage.

Redox-linked effects of green tea on DNA damage and repair, and influence of microsatellite polymorphism in HMOX-1: results of a human intervention trial.

Green tea has many reported health benefits, including genoprotective and antioxidant effects, but green tea has pro-oxidant activity in vitro. A tea-induced pro-oxidant shift that triggers cytoprotective adaptations has been postulated, but human data are lacking. We investigated effects on oxidation-induced DNA damage and redox-linked cytoprotective factors, including 8-oxoguanine glycosylase (hOGG1) and heme oxygenase 1 (HMOX-1) in lymphocytes in a randomised, placebo-controlled, cross-over supplementation trial. hOGG1 catalyses the first step in base excision repair; increased HMOX-1 is a sign of cytoprotective response to pro-oxidant change. The influence of microsatellite polymorphisms in the HMOX-1 promoter region was also explored. Higher numbers of GT repeats [GT(n)] in this region reportedly diminish response to pro-oxidant change. Green tea [2 × 150 ml of 1% w/v tea/day (or water as control)] was taken for 12 weeks by 43 Type 2 diabetes subjects {20 with short [S/S; GT(n) < 25] and 23 with long [L/L; GT(n) ≥ 25]}. Fasting venous blood was collected before and after each treatment. The formamidopyrimidine DNA glycosylase-assisted comet assay was used to measure DNA damage in lymphocytes. For measuring hOGG1 activity, we used photo-damaged HeLa cells incubated with lymphocyte extracts from test subjects, in combination with the comet assay. Lymphocyte HMOX-1 and hOGG1 protein concentrations and expression (mRNA) of redox-sensitive genes, including HMOX-1 and hOGG1, were also investigated. Results showed significantly (P < 0.01) lower (~15%) DNA damage, higher (~50%) hOGG1 activity and higher (~40%) HMOX-1 protein concentration after tea. No changes in mRNA expression were seen. Baseline HMOX-1 protein and hOGG1 activity were higher (P < 0.05) in the S/S group, but tea-associated responses were similar in both GT(n) groups. Green tea is clearly associated with lowered DNA damage, increased hOGG1 activity and higher HMOX-1 protein levels. Further study is needed to confirm a cause and effect relationship and to establish if these effects are mediated by post-translational changes in proteins or by increased gene expression.

Effects of single dose and regular intake of green tea (Camellia sinensis) on DNA damage, DNA repair, and heme oxygenase-1 expression in a randomized controlled human supplementation study.

Regular intake of green tea (Camellia sinensis) lowers DNA damage in humans, but molecular mechanisms of genoprotection are not clear. Protection could be via direct antioxidant effects of tea catechins, but, paradoxically, catechins have pro-oxidant activity in vitro, and it is hypothesized that mechanisms relate to redox-sensitive cytoprotective adaptations. We investigated this hypothesis, focusing particularly on effects on the DNA repair enzyme human oxoguanine glycosylase 1 (hOGG1), and heme oxygenase-1, a protein that has antioxidant and anti-inflammatory effects. A randomized, placebo-controlled, human supplementation study of crossover design was performed. Subjects (n = 16) took a single dose (200 mL of 1.5%, w/v) and 7-days of (2 × 200 mL 1%, w/v per day) green tea (with water as control treatment). Lymphocytic DNA damage was ∼30% (p < 0.001) lower at 60 and 120 min after the single dose and in fasting samples collected after 7-day tea supplementation. Lymphocytic hOGG1 activity was higher (p < 0.0001) at 60 and 120 min after tea ingestion. Significant increases (p < 0.0005) were seen in hOGG1 activity and heme oxygenase-1 after 7 days. Results indicate that molecular triggering of redox-sensitive cytoprotective adaptations and posttranslational changes affecting hOGG1 occur in vivo in response to both a single dose and regular intake of green tea, and contribute to the observed genoprotective effects of green tea.

Antioxidants in food: content, measurement, significance, action, cautions, caveats, and research needs.

There are a multitude of antioxidants in foods, especially in foods of plant origin. Higher intake of antioxidant-rich foods is clearly associated with better health and functional longevity. The specific agents and mechanisms responsible are not yet clear, but there is convincing evidence that including more plant-based, antioxidant-rich foods, herbs, and beverages in the diet is effective in promoting health and lowering risk of various age-related diseases. The content of some individual antioxidants, such as vitamin C, in food can be measured, but it is not feasible to attempt to measure each antioxidant separately, and methods have been developed to assess the "total antioxidant content" of foods. One of the most widely used methods is the ferric reducing/antioxidant power (FRAP) assay, which is relatively simple, quick, sensitive, and inexpensive to perform. There are many published studies that have used the FRAP assay, and these have generated a very large database of total antioxidant content of foods that can help guide food choices for increased antioxidant intake. The FRAP assay has also been used to assess the bioavailability of antioxidants in foods and to investigate the effects of growing conditions, storage, processing, and cooking method on the total antioxidant content of food. The test can be employed as a quality control check device, and to detect adulteration of food. Furthermore, in a modified form (FRASC), the assay can measure ascorbic acid content almost simultaneously with the total antioxidant content of the sample. In this chapter, basic concepts of oxidation and the role of antioxidants, as well as the types and action of different antioxidants in foods will be reviewed briefly, and the underpinning concepts and evidence for health benefits of increased intake of dietary antioxidants will be discussed, with some focus on vitamin C, and also in the context of our evolutionary development. The basic concepts and limitations of measuring "total antioxidant content" of food will be presented. The FRAP assay and the modified version FRASC will be described, and the total antioxidant content (as the FRAP value) of a range of foods will be presented. Finally, issues of bioavailability and redox balance will be discussed in relation to the biological significance and molecular action of antioxidants in foods, some caution and caveats are presented about overcoming biological barriers to absorption of antioxidant phytochemicals, and research needs to further our understanding in the important area of food, antioxidants, and health will be highlighted.

Plasma allantoin measurement by isocratic liquid chromatography with tandem mass spectrometry: method evaluation and application in oxidative stress biomonitoring.

BACKGROUND: Allantoin in human plasma is a specific biomarker of oxidative stress. We describe a sensitive method to measure plasma allantoin using isocratic liquid chromatography and mass spectrometry (LC-MS/MS). METHODS: Direct injection of deproteinized plasma into the LC-MS/MS system was performed. The method was technically evaluated. Results on 200 healthy and 35 Type 2 diabetic Chinese subjects were compared. RESULTS: Dose-response of allantoin was linear to at least 21 pmol (20 µmol/l in plasma); LOD was 0.16 pmol; recovery 99.2-100.2% at 1-5 µmol/l; accuracy, 98.5-100.8%; within-day and between-day CVs (n=6), <4.0% (at 5.00-40 µmol/l) and <2.0% (at 1-5 µmol/l), respectively. Plasma allantoin in diabetic patients was ~8-fold higher than in healthy subjects; mean (SD): 8.82 (7.26) and 1.08 (0.86) µmol/l, respectively (p<0.0001). Allantoin was slightly higher in healthy men than in age- and BMI-matched women: 1.21 (0.99) µmol/l, n=88 compared to 0.97 (0.74) µmol/l, n=112; p<0.001. No association with age was seen. Gender difference was also seen in the diabetes patients: men, n=14, 11.57 (8.57) µmol/l; women, n=21, 6.99 (5.75) µmol/l, p<0.05. CONCLUSIONS: Based on 95th percentiles of the healthy subjects, plasma allantoin of >2.2 µmol/l in women and >3.1 µmol/l in men indicates increased oxidative stress. Allantoin in diabetes subjects is clearly and markedly increased. The method will facilitate future studies of oxidative stress in human biomonitoring studies.

Comparison of catechin profiles in human plasma and urine after single dosing and regular intake of green tea (Camellia sinensis).

Green tea (Camellia sinensis) catechin profiles in plasma and urine following single dosing and regular ingestion of green tea are not clear. We performed a placebo-controlled intervention study with sixteen healthy volunteers to determine changes in total and free catechins after a single dose and following 1 week of twice-daily green tea. Blood and urine samples were collected before (fasting) and after (60 and 120 min for blood; 90 and 180 min for urine) drinking 200 ml of 1.5% (w/v) green tea or water (n 8 each), and fasting samples were again collected after 7 d of 150 ml of 1% (w/v) supplemental green tea or water twice daily. After a 4-week washout, subjects were crossed onto the other treatment and procedures repeated. Plasma results at 1 h post-ingestion showed elevated (P < 0.05) mean epigallocatechin gallate (EGCG; 310 (SD 117) nmol/l; all in free form), epigallocatechin (EGC; 192 (SD 67) nmol/l; 30% free) and epicatechin gallate (ECG; 134 (SD 51) nmol/l; 75% free). Fasting plasma after 7 d of regular intake showed increased (P < 0.05) EGCG (80 v. 15 nmol/l at baseline) and ECG (120 v. 40 nmol/l), with > or =90% of both in their conjugated forms. Total EGC was < 10 nmol/l. Post-ingestion conjugation and renal loss of EGC and epicatechin were rapid and high, but were negligible for EGCG and ECG. In the green tea consumed, the content was EGCG > EGC > ECG, and the acute plasma response mirrored this. However, after chronic consumption there was almost no EGC found in fasting plasma, some EGCG was present, but a rather high level of ECG was maintained.

Heme oxygenase microsatellite polymorphism, oxidative stress, glycemic control, and complication development in type 2 diabetes patients.

Heme oxygenase-1 (HMOX-1) is activated by oxidative stress, and gene responsiveness is reportedly determined by the number of dinucleotide (GT(n)) repeats in its highly polymorphic promoter region. "Short" (S; GT(n)<25) alleles reportedly associate with higher response, lower oxidative stress, lower risk of type 2 diabetes mellitus (type 2DM), and better glycemic control and outcome, but data are conflicting. We investigated GT(n) in type 2DM subjects (all ethnic Chinese) in relation to basal glycemic control, oxidative stress, and outcome during up to 9 years' follow-up. Fasting blood from 418 type 2 DM subjects was collected at entry for GT(n) genotyping, glycated hemoglobin, glucose, lipids, and biomarkers of oxidative stress and antioxidants. A subset (n=368) was followed for up to 9 years for incident complications or death. GT(n) genotype distribution was 128, 182, and 108 for, respectively, S/S, S/L, and L/L. No significant differences in glycemic control, lipids, or oxidative stress were seen across genotypes. During follow-up, 168/368 subjects developed complications. No association was seen with GT(n). No difference in plasma HO-1 was seen between genotypes in a small substudy (S/S n=21 vs L/L n=23). Glycated hemoglobin and lymphocytic DNA damage was higher (p<0.05) at entry in the incident complications group. No other significant differences were seen in oxidative stress or antioxidants. Data do not support the postulated link between HMOX-1 microsatellite polymorphism and type 2 DM or the putative beneficial effect of the S allele on glycemic control, oxidative stress, or outcome in type 2 DM patients, at least in this particular population.

Increasing the antioxidant content of food: a personal view on whether this is possible or desirable.

A commonly held belief is that higher intake of antioxidants will promote better health through enhanced antioxidant status and lowered oxidative stress. However, the benefits of antioxidant-rich foods have not been reproduced in supplementation trials with pure antioxidants. This has driven research and commercial interest in foods, including traditional foods and their components, with enhanced antioxidant content and improved antioxidant bioavailability, which in many cases is very low. In this paper, evidence for the health benefits of antioxidant-rich foods and methods to increase the antioxidant content and bioavailability of food antioxidants are reviewed briefly, and the concept that increased food antioxidant content/intake per se is beneficial is examined from a cautionary perspective, considering issues of low bioavailability, rapid catabolism, biotransformation and the paradoxical pro-oxidant effects of dietary antioxidants.

Study of potential cardioprotective effects of Ganoderma lucidum (Lingzhi): results of a controlled human intervention trial.

Previous studies have suggested that Lingzhi (Ganoderma lucidum) has antioxidant effects and possibly beneficial effects on blood pressure, plasma lipids and glucose, but these have not been confirmed in subjects with mild hypertension or hyperlipidaemia. The objective of the present study was to assess the cardiovascular, metabolic, antioxidant and immunomodulatory responses to therapy with Lingzhi in patients with borderline elevations of blood pressure and/or cholesterol in a controlled cross-over trial. A total of twenty-six patients received 1·44 g Lingzhi daily or matching placebo for 12 weeks in a randomised, double-blind, cross-over study with placebo-controlled run-in and cross-over periods. Body weight, blood pressure, metabolic parameters, urine catecholamines and cortisol, antioxidant status and lymphocyte subsets were measured after each period. Lingzhi was well tolerated and data from twenty-three evaluable subjects showed no changes in BMI or blood pressure when treated with Lingzhi or placebo. Plasma insulin and homeostasis model assessment-insulin resistance were lower after treatment with Lingzhi than after placebo. TAG decreased and HDL-cholesterol increased with Lingzhi but not with placebo in the first treatment period, but significant carry-over effects prevented complete analysis of these parameters. Urine catecholamines and cortisol, plasma antioxidant status and blood lymphocyte subsets showed no significant differences across treatments. Results indicate that Lingzhi might have mild antidiabetic effects and potentially improve the dyslipidaemia of diabetes, as shown previously in some animal studies. Further studies are desirable in patients with hyperglycaemia.

DNA protective effect of ginseng and the antagonistic effect of Chinese turnip: a preliminary study.

The genoprotective effect of American and Asian ginseng on human lymphocytic DNA was studied. Using the comet assay, aqueous extracts of both types of ginseng were shown to diminish hydrogen peroxide-induced DNA damage. In contrast, and in accordance with traditional Chinese medicine beliefs, addition of the juice from Chinese turnip counteracted the beneficial effect of ginseng. Results showed that incubating ginseng along with turnip juice abolished the DNA protective effect of both American and Asian ginseng. Although the exact mechanism has not been elucidated, the counteracting effect of turnip on ginseng seems unlikely to be mediated by enzymatic action as the effect was seen with boiled as well as unboiled turnip extract.

Antioxidant content and ultraviolet absorption characteristics of human tears.

PURPOSE: Dry eye syndrome is a common age-related disorder, and decreased antioxidant/ultraviolet (UV) radiation protection in tears may be part of the cause. This study aimed to compare the tear antioxidant content and flow rate in young and older adults. The total antioxidant content and UV absorbing properties of various commercially available ophthalmic solutions used to alleviate dry eye symptoms were also examined. METHODS: Minimally stimulated tears were collected from 120 healthy Chinese adults with no ocular pathology. Two age groups were studied: 19 to 29 years (n = 58) and 50 to 75 years (n = 62). Tear samples from each subject and 13 ophthalmic solutions were analyzed for total antioxidant content (as the Ferric Reducing/Antioxidant Power value). Tear flow rates were estimated from time taken to collect a fixed volume of tear fluid. UV absorbance spectra of pooled fresh reflex tear fluid and the ophthalmic solutions were determined. RESULTS: Results showed that the antioxidant content of minimally stimulated tears from older subjects (398 ± 160 µmol/l) was not significantly lower than that of younger subjects (348 ± 159 µmol/l; p = 0.0915). However, there was a significant difference in the tear flow rates between the two groups (p < 0.0001), with the younger group having three to four fold higher flow rate. None of the commercial preparations tested had detectable antioxidant content, and none showed the UV absorption characteristics of natural reflex tears. CONCLUSIONS: The effect of low flow rate on the dynamic antioxidant supply to the corneal surface indicates that older subjects have poorer overall defense against photooxidative and other oxidative processes. This could predispose older persons to corneal stress and development of dry eye syndrome. The commercially available artificial tears tested lack both the antioxidant content and UV absorbing characteristics of natural tears. Artificial tears formulations that help restore natural antioxidant and UV absorbing properties to the tear film of the aging eye may help prevent or improve dry eye symptoms and promote ocular health.

Relationships among diabetic retinopathy, antioxidants, and glycemic control.

PURPOSE: Type 2 Diabetes Mellitus (DM) is increasing worldwide and affects ∼11% of the Hong Kong population. Diabetic retinopathy (DR) is a common cause of vision loss in type 2 DM. Risk of DR is increased by poor glycemic control, elevated lipids, and blood pressure, but it is not possible to predict the development or progression of DR at an individual level. Increased oxidative stress is thought to play a role. The use of a wider biomarker profile incorporating biomarkers of antioxidant status and oxidative stress may aid identification of individuals at higher risk or at very early stages of developing DR. METHODS: Four hundred twenty type 2 DM subjects without diabetic complications were investigated. Eyes were examined for DR and anterior and posterior ocular segment pathology. DR was graded according to Early Treatment Diabetic Retinopathy Study criteria. Demographic data were collected. Traditional risk factors plus biomarkers of antioxidant status and oxidative stress in fasting blood and urine were determined. RESULTS: Overall DR prevalence was 89%. No significant differences in any demographic measures or biomarkers were found among those subjects with different DR grades, or in those without DR. Significant correlations (p < 0.0001) between HbA1c and DNA damage, (ρ = 0.32) and fasting plasma glucose and DNA damage (ρ = 0.52) were seen. DNA damage was also significantly and inversely correlated (p < 0.0001) with both plasma ascorbic acid (ρ = -0.41) and plasma total antioxidant level (ρ = -0.21). CONCLUSIONS: DR prevalence was very high in this group, but no biomarker differences were seen in those with DR compared to those free of DR, or in those with different degrees of severity of DR. This group of 420 subjects is being followed up to investigate whether the extended biomarker profile at baseline is related to progression of and/or incident DR.

Genoprotective effects of green tea (Camellia sinensis) in human subjects: results of a controlled supplementation trial.

Green tea is rich in polyphenolic antioxidants and has widely reported but largely unsubstantiated health benefits. In the present study, genoprotective effects of two types of green tea were studied both in an in vitro and in a human supplementation trial. For the in vitro study, human lymphocytes were pre-incubated in tea (0·005-0·1 %, w/v), washed and subjected to oxidant challenge induced by H2O2. In a placebo-controlled, cross-over supplementation study, eighteen healthy volunteers took 2 x 150 ml/d of 1% (w/v) green tea ('Longjing' green tea or 'screw-shaped' green tea) or water (control) for 4 weeks (n 6). Subjects took all the three treatments in a random order, with 6 weeks' washout between each treatment. Fasting blood and urine were collected before and after each treatment. The comet assay was used to measure the resistance of lymphocytic DNA to H2O2-induced challenge. Basal oxidation-induced DNA damage was measured using the formamidopyrimidine glycosylase (Fpg) enzyme-assisted comet assay. Urine 7,8-dihydro-2-deoxyguanosine (8-oxodG, mol/mmol creatinine), a biomarker of whole-body oxidative stress, was measured by liquid chromatography with tandem MS. In vitro testing results of tea-treated cells showed increased (P < 0·05) resistance of DNA to the challenge. In the supplementation trial, a significant (P < 0·05) increase in resistance was also observed. Furthermore, the FPg comet data showed .20% decrease in DNA damage with tea supplementation: mean and standard deviation changes in %DNA in comet tail in the Fpg-assisted comet assay were: -5·96 (SD 3·83) % after Longjing tea; -6·22 (SD 3·34) % after screw-shaped tea; +0·91 (SD 5·79) % after water (P < 0·05). No significant changes in urine 8-oxodG were seen. The results indicate that green tea has significant genoprotective effects and provide evidence for green tea as a 'functional food'.

Cryopreservation and storage effects on cell numbers and DNA damage in human lymphocytes.

The comet assay measures DNA damage in individual cells (usually lymphocytes) and is widely used in biomonitoring studies. Lymphocytes are harvested and are usually cryopreserved for batch testing. We investigated cell loss during harvesting, cryopreservation, thawing, and washing of human peripheral lymphocytes and compared DNA damage, using the Fpg-assisted comet assay for oxidation-induced DNA lesions, in freshly harvested cells and cells that were thawed and tested after cryopreservation of 2-3 days and 4 weeks. Lymphocyte numbers were measured in fresh venous blood and after the steps of harvesting, cryopreservation, and washing. Results showed that >50% of lymphocytes in whole blood were harvested, but ∼60% were lost during washing. Loss during washing was not different (P>0.05) between fresh cells and cells thawed and washed after 2-3 days or 4 weeks cryopreservation. No change in DNA damage was seen after cryopreservation and thawing: mean (SD) % DNA in comet tail was 11.2 (1.53) in freshly harvested cells, 12.9 (1.39) in 2-3 days cryopreserved cells, and 12.9 (2.0) in cells tested after 4 weeks cryopreservation (P>0.05). Results indicate that there is no predominant loss of more highly damaged cells during cryopreservation and thawing and there is no induction of oxidation-induced DNA lesions in cryopreserved cells stored for up to 4 weeks.

Vegetarian diets and public health: biomarker and redox connections.

Vegetarian diets are rich in antioxidant phytochemicals. However, they may not act as antioxidants in vivo, and yet still have important signaling and regulatory functions. Some may act as pro-oxidants, modulating cellular redox tone and oxidizing redox sensitive sites. In this review, evidence for health benefits of vegetarian diets is presented from different perspectives: epidemiological, biomarker, evolutionary, and public health, as well as antioxidant. From the perspective of molecular connections between diet and health, evidence of a role for plasma ascorbic acid as a biomarker for future disease risk is presented. Basic concepts of redox-based cell signaling are presented, and effects of antioxidant phytochemicals on signaling, especially via redox tone, sulfur switches and the Antioxidant Response Element (ARE), are explored. Sufficient scientific evidence exists for public health policy to promote a plant-rich diet for health promotion. This does not need to wait for science to provide all the answers as to why and how. However, action and interplay of dietary antioxidants in the nonequilibrium systems that control redox balance, cell signaling, and cell function provide rich ground for research to advance understanding of orthomolecular nutrition and provide science-based evidence to advance public health in our aging population.

Colour additives in snack foods consumed by primary school children in Hong Kong.

The objective of the present study was to assess synthetic colours in common snack foods consumed by children and the accuracy of labelling. Dietary exposure to synthetic colours was estimated using food frequency questionnaire data obtained from primary school children in Hong Kong. The concentration of synthetic colours in food items consumed was determined by HPLC with photodiode array detection. Dietary exposure to synthetic colours for an average primary school student was considerably lower than the acceptable daily intake for their age. Estimates fell below the maximum acceptable daily intake established by the Food and Agriculture Organization/World Health Organization (FAO/WHO) and European Food Safety Authority (ESFA). However, data from HPLC analyses showed that several synthetic colours, which were labelled as being present in the food, were not detected and vice versa.

Urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a specific marker of oxidative stress, using direct, isocratic LC-MS/MS: Method evaluation and application in study of biological variation in healthy adults.

BACKGROUND: Urine 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a specific biomarker of oxidative stress. We evaluated a modified LC-MS/MS assay for urine 8-oxodG and determined biological variation in healthy adults. METHOD: Untreated urine was injected into an isocratic LC-MS/MS system (positive-ion MRM mode). Urine 8-oxodG in 51 healthy volunteers was measured; within- and between-day variations in 23 healthy volunteers were investigated. RESULTS: Dose-response was linear to 452 nmol/l; limit of detection=2.3 nmol/l; within-run and between-run CVs were <3.0% and <4.7%, respectively; recovery=97%-101%; accuracy=97.7-103.5%. Urine 8-oxodG (median, mean [SD]): 1.70, 1.70[0.60]nmol/mmol creatinine (n=51). Men had higher (p=0.027) concentrations than women matched for age and body mass index: mean [SD]: 1.90[1.60]; n=26 vs. 1.50[0.55]; n=25. Within- and between-day variations were wide but random. No significant differences were seen overall across time-points within 1 day or at the same time-point across 5 consecutive days. CONCLUSIONS: The method has advantages of speed and relative simplicity as it does not require sample pre-treatment for 8-oxodG extraction, the use of internal standard or gradient LC elution and has high linearity, specificity, precision and recovery. Biological variation in urine 8-oxodG is wide, but no within- or between-day differences at the group concentration were seen in healthy adults.