Systematic review: primary and secondary prevention of gastrointestinal cancers with antioxidant supplements

Causal association between dietary factors and esophageal diseases: A Mendelian randomization study

BACKGROUND

Using Mendelian randomization (MR) approach, our objective was to determine whether there was a causal association between dietary factors and gastroesophageal reflux disease (GERD), Barrett's esophagus (BE), or esophageal cancer (EC).

METHODS

Genome-wide association study (GWAS) data for eighteen types of dietary intake were obtained from the UK Biobank. GWAS data for GERD, BE, and EC were sourced from the FinnGen consortium. We performed univariable and multivariable MR analysis to assess the cause effect between dietary factors and esophageal diseases. MR results were expressed as odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

Raw vegetable intake was associated with a lower risk of GERD (OR = 0.478; P = 0.011). On the contrary, cooked vegetable intake increased the risk of GERD (OR = 1.911; P = 0.024). Bread intake was associated with increased odds of BE (OR = 6.754; P = 0.007), while processed meat intake was associated with reduced risk of BE (OR = 0.210; P = 0.035). We also observed evidence that increased consumption of dried fruit (OR = 0.087; P = 0.022) and salt added to food (OR = 0.346; P = 0.045) could prevent EC. The results of multivariable MR showed that the protective effect of consumption of salt added to food on EC was no longer significant after adjusting for the consumption of dried fruit.

CONCLUSION

Vegetable consumption was associated with GERD, whereas consumption of bread and processed meat was associated with BE. Dried fruit intake was associated with a lower risk of EC, and the protective effect of consumption of salt added food on EC may also be mediated by consumption of dried fruit. Future research should be performed to investigate the mechanisms behind these cause-and-effect relationships to reduce the burden of disease caused by dietary habits.

Diet and Risk of Gastric Cancer: An Umbrella Review

Several dietary exposures have been associated with gastric cancer (GC), but the associations are often heterogenous and may be afflicted by inherent biases. In the context of an Umbrella Review (UR), we provide an overview and a critical evaluation of the strength and quality, and evidence classification of the associations of diet-related exposures in relation to the risk of GC. We searched PubMed and Scopus for eligible meta-analyses of observational studies published in English from inception to 12 December 2021, and for any identified association, we applied robust epidemiological validity evaluation criteria and individual study quality assessment using AMSTAR. We screened 3846 titles/abstracts and assessed 501 full articles for eligibility, of which 49 were included in the analysis, investigating 147 unique exposures in relation to GC, cardia (GCC) or non-cardia (GNCC) cancer. Supported by suggestive evidence, positive associations were found comparing the highest vs. lowest categories for: heavy (>42 g/day) alcohol consumption (Relative Risk (RR) = 1.42, 95% Confidence Interval (CI): 1.20−1.67), salted fish consumption (RR = 1.56, 95% CI:1.30−1.87) and waist circumference (RR = 1.48, 95% CI:1.24−1.78) and an inverse association for the healthy lifestyle index (RR = 0.60, 95% CI:0.48−0.74) in relation to GC. Additionally, a positive association was found comparing obese individuals (Body Mass Index (BMI) ≥ 30) to normal-weight individuals (BMI: 18.5−25) (RR = 1.82, 95% CI:1.32−2.49) in relation to GCC. Most of the meta-analyses were of medium-to-high quality (median items: 7.0, interquartile range: 6−9). Maintaining a normal body weight and adopting healthy dietary choices, in particular, limiting the consumption of salt-preserved foods and alcohol, can reduce the risk of gastric cancer.

A Narrative Review of the Safety of Anti-COVID-19 Nutraceuticals for Patients with Cancer

Simple Summary

Dietary supplement use has increased more than 35% globally since the COVID-19 outbreak. While some nutraceuticals are potentially efficacious against severe disease from COVID-19, their indiscriminate use by patients with cancer without medical supervision is concerning. The aim of this narrative review was to evaluate the data on safety of “anti-COVID-19” nutraceuticals for patients with cancer. We found that the use of vitamin C, vitamin D, and selenium supplements is likely safe and even potentially beneficial at typically recommended doses. However, caution is advised regarding the use of omega-3 fatty acids and zinc, as risks from their use may outweigh the benefits.

Abstract

Interest in dietary supplements and their efficacy in treating and preventing disease has increased greatly since the outbreak of the COVID-19 pandemic. Due to the risk of severe COVID-19 in patients with cancer, we conducted a narrative review aiming to better understand the data on the safety of the most efficacious “anti-COVID-19” nutraceuticals for patients with cancer. We conducted a PubMed database search aimed at identifying the most effective nutrients for use against COVID-19. For the identified nutraceuticals, we searched PubMed again regarding their safety for patients with cancer. Fifty-four total records (52 independent studies) were retrieved, pertaining to vitamin D, vitamin C, selenium, omega-3 fatty acids, and zinc. Vitamin D results from 23 articles indicated safe use, but two articles indicated potential harm. All 14 articles for vitamin C and five out of six articles for selenium indicated the safety of use (one study for selenium suggested harm with high-dose supplementation). Results for omega-3 fatty acids (seven articles) and zinc (one article), however, were rather mixed regarding safety. We conclude that vitamin D, vitamin C, and selenium supplements are likely safe or even beneficial at typically recommended doses; however, caution is urged with omega-3 fatty acid supplements, and zinc supplements should likely be avoided. More experimental research is needed, and nutraceutical use by patients with cancer should always be under the supervision of a healthcare team.

Antixoxidant Supplements versus Health Benefits of Brief/Intermittent Exposure to Potentially Toxic Physical or Chemical Agents

Although antioxidants can act locally to react with an oxidant, oral administration of "antioxidants" is quite useless in treating oxidative stress in tissues. Furthermore, it does not make sense to consider a vitamin as an antioxidant, but vitamin B3 leads to the in vivo formation of compounds that are essential for reducing this stress. A rigorous treatment of the subject indicates that to deal with oxidative stress, the most direct approach is to enhance the innate antioxidant mechanisms. The question is whether this is possible through daily activities. Diets can contain the necessary components for these mechanisms or may induce the expression of the genes involved in them. Another possibility is that pro-oxidant molecules in food increase the sensitivity and power of the detoxification pathways. This option is based on well-known DNA repair mechanisms after exposure to radiation (even from the Sun), or strong evidence of induction of antioxidant capacity after exposure to powerful pro-oxidants such as H₂O₂. More experimental work is required to test whether some molecules in food can increase the expression of antioxidant enzymes and/or improve antioxidant mechanisms. Identifying effective molecules to achieve such antioxidant power is critical to the food and nutraceutical industries. The potential of diet-based interventions to combat oxidative stress must be viewed from a new perspective.

Selenium and cancer or adenoma related to the large bowel

The protective effect of selenium against colorectal cancer or adenoma is still a controversial issue. Although there are well-described (pato)physiological protective mechanisms of selenium against colorectal cancer, the results of the studies from 1998-2018 are inconclusive and need to be considered in the future. Neither observational nor experimental studies present consistent results. Although the Cochrane review showed that well-designed randomized clinical trials (RCTs) presented no beneficial effect of selenium supplementation on cancer incidence, well-designed RCTs confirming the protective effect of selenium supplementation against colorectal adenoma or colorectal polyp recurrence have been found in subject-related literature. In the reviewed studies, selenium concentration was measured in the blood serum/toenail or in diet. It is of great importance to highlight that blood selenium concentration depends on the concentration of this micronutrient in food, which in turn depends on selenium content in soil, bioavailability of selenium, which is different in various geographical regions, and forms of selenium. Selenium circulating in blood as a component of selenoproteins participates in oxidoreduction, thus reducing the risk of developing colorectal cancer. Despite this well-known protective mechanism against colorectal cancer occurrence, half of the reviewed studies did not confirm the protective properties of selenium. To sum up, the current state of knowledge on the association between selenium and colorectal cancer or adenoma has revealed not only inconclusive results of the studies, but has also shown that there is a need to conduct more prospective studies focused on selenium supplementation and colorectal cancer as this research is limited.

Selenium Status in Elderly People: Longevity and Age-Related Diseases

BACKGROUND

Selenium (Se) is a trace element active in selenoproteins, which can regulate oxidative stress. It is generally perceived as an import factor for maintaining health in the elderly.

METHODS

The goal of this review is to discuss selenium concentration in biological samples, primarily serum or plasma, as a function of age and its relation with longevity. The elemental level in various age-related diseases is reviewed.

CONCLUSION

Highest selenium values were observed in healthy adults, while in an elderly population significantly lower concentrations were reported. Variables responsible for contradictory findings are mentioned. Risk and benefits of Se-supplementation still remain under debate.

Sulforaphane: Its "Coming of Age" as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease

A growing awareness of the mechanisms by which phytochemicals can influence upstream endogenous cellular defence processes has led to intensified research into their potential relevance in the prevention and treatment of disease. Pharmaceutical medicine has historically looked to plants as sources of the starting materials for drug development; however, the focus of nutraceutical medicine is to retain the plant bioactive in as close to its native state as possible. As a consequence, the potency of a nutraceutical concentrate or an extract may be lower than required for significant gene expression. The molecular structure of bioactive phytochemicals to a large extent determines the molecule's bioavailability. Polyphenols are abundant in dietary phytochemicals, and extensive in vitro research has established many of the signalling mechanisms involved in favourably modulating human biochemical pathways. Such pathways are associated with core processes such as redox modulation and immune modulation for infection control and for downregulating the synthesis of inflammatory cytokines. Although the relationship between oxidative stress and chronic disease continues to be affirmed, direct-acting antioxidants such as vitamins A, C, and E, beta-carotene, and others have not yielded the expected preventive or therapeutic responses, even though several large meta-analyses have sought to evaluate the potential benefit of such supplements. Because polyphenols exhibit poor bioavailability, few of their impressive in vitro findings have been replicated in vivo. SFN, an aliphatic isothiocyanate, emerges as a phytochemical with comparatively high bioavailability. A number of clinical trials have demonstrated its ability to produce favourable outcomes in conditions for which there are few satisfactory pharmaceutical solutions, foreshadowing the potential for SFN as a clinically relevant nutraceutical. Although myrosinase-inert broccoli sprout extracts are widely available, there now exist myrosinase-active broccoli sprout supplements that yield sufficient SFN to match the doses used in clinical trials.

Serum selenium and pancreatic cancer: a prospective study in the Prostate, Lung, Colorectal and Ovarian Cancer Trial cohort

PURPOSE

Pancreatic cancer(PCa) is one of the most lethal cancers with few known consistent nutrition-related risk factors. Epidemiologic associations between the trace element selenium and PCa are inconsistent. This study examined the association of pre-diagnostic serum selenium with incident PCa.

METHODS

We conducted a nested case-control study within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Study (PLCO) cohort of men and women 55-70 years old at baseline (1993-2001). In total, 303 PCa cases developed during the 17-year follow-up period (1993-2009). We selected two controls (n = 606) for each case who were alive at the time the case was diagnosed who were matched on age, sex, race, and date of blood draw. We used conditional logistic regression analysis to calculate the odds ratio (OR) and 95% confidence intervals (CI) adjusting for smoking status and diabetes mellitus.

RESULTS

Mean serum selenium concentrations were slightly lower in cases (mean, 95% CI: 139.0 ng/ml, 135.6-138.9) compared to controls (142.5 ng/ml, 140.4-142.4, p = 0.08). Overall, serum selenium was not associated with PCa risk (continuous OR: 0.66; 0.32-1.37). There was no significant interaction by sex, smoking, diabetes, or follow-up time (p > 0.05).

CONCLUSION

Our results do not support the hypothesis that serum selenium is associated with PCa risk.

Vitamin E consumption and the risk of bladder cancer

Background: Vitamin E has anti-cancer properties, which was demonstrated mainly due to its antioxidant effect. Several epidemiological studies have investigated the association between vitamin E consumption and the risk of bladder cancer. However, the results were inconsistent. The meta-analysis study aimed to evaluate the association of vitamin E consumption and the risk of bladder cancer.

METHODS

We conducted a systematic literature search in the electronic databases, which included MEDLINE, EMBASE and the Cochrane Library till 1 January 2016. The pooled relative risk ratios (RRs) with 95% confidence intervals (CIs) were calculated depending on the heterogeneity among studies. Subgroup analysis and sensitivity analysis were also performed. Publication bias was assessed using Begg's test and Egger's test.

RESULTS

A total of 11 prospective studies (3 randomized clinical trials and 8 cohort studies) including 575601 participants were identified to be eligible for our present meta-analysis. The pooled RRs with 95% CI for highest versus lowest vitamin E consumption was 0.89 (0.78-1.00). An inverse linear association between vitamin E consumption and bladder cancer risk was detected in the dose response analysis. The results were also stable in the subgroup analysis and sensitivity analysis. Meanwhile, no obvious publication bias was observed.

CONCLUSIONS

Our study indicates that vitamin E consumption was inversely associated with the risk of bladder cancer.

Potential application of the oxidative nucleic acid damage biomarkers in detection of diseases

Reactive oxygen species (ROS) are generated after exposure to harmful environmental factors and during normal cellular metabolic processes. The balance of the generating and scavenging of ROS plays a significant role in living cells. The accumulation of ROS will lead to oxidative damage to biomolecules including nucleic acid. Although many types of oxidative nucleic acid damage products have been identified, 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoG) has been commonly chosen as the biomarkers of oxidative damage to DNA and RNA, respectively. It has been demonstrated that oxidative damage to nucleic acid is an initiator in pathogenesis of numerous diseases. Thus, oxidative nucleic acid damage biomarkers have the potential to be utilized for detection of diseases. Herein, we reviewed the relationship of oxidative nucleic acid damage and development of various diseases including cancers (colorectal cancer, gastrointestinal cancer, breast cancer, lung cancer, epithelial ovarian carcinoma, esophageal squamous cell carcinoma), neurodegenerative disorders and chronic diseases (diabetes and its complications, cardiovascular diseases). The potential of oxidative nucleic acid damage biomarkers for detection of diseases and drug development were described. Moreover, the approaches for detection of these biomarkers were also summarized.

A synopsis on aging-Theories, mechanisms and future prospects

Answering the question as to why we age is tantamount to answering the question of what is life itself. There are countless theories as to why and how we age, but, until recently, the very definition of aging - senescence - was still uncertain. Here, we summarize the main views of the different models of senescence, with a special emphasis on the biochemical processes that accompany aging. Though inherently complex, aging is characterized by numerous changes that take place at different levels of the biological hierarchy. We therefore explore some of the most relevant changes that take place during aging and, finally, we overview the current status of emergent aging therapies and what the future holds for this field of research. From this multi-dimensional approach, it becomes clear that an integrative approach that couples aging research with systems biology, capable of providing novel insights into how and why we age, is necessary.

Paleolithic and Mediterranean Diet Pattern Scores Are Inversely Associated with Biomarkers of Inflammation and Oxidative Balance in Adults

BACKGROUND

Chronic inflammation and oxidative balance are associated with poor diet quality and risk of cancer and other chronic diseases. A diet-inflammation/oxidative balance association may relate to evolutionary discordance.

OBJECTIVE

We investigated associations between 2 diet pattern scores, the Paleolithic and the Mediterranean, and circulating concentrations of 2 related biomarkers, high-sensitivity C-reactive protein (hsCRP), an acute inflammatory protein, and F2-isoprostane, a reliable marker of in vivo lipid peroxidation.

METHODS

In a pooled cross-sectional study of 30- to 74-y-old men and women in an elective outpatient colonoscopy population (n = 646), we created diet scores from responses on Willett food-frequency questionnaires and measured plasma hsCRP and F2-isoprostane concentrations by ELISA and gas chromatography-mass spectrometry, respectively. Both diet scores were calculated and categorized into quintiles, and their associations with biomarker concentrations were estimated with the use of general linear models to calculate and compare adjusted geometric means, and via unconditional ordinal logistic regression.

RESULTS

There were statistically significant trends for decreasing geometric mean plasma hsCRP and F2-isoprostane concentrations with increasing quintiles of the Paleolithic and Mediterranean diet scores. The multivariable-adjusted ORs comparing those in the highest with those in the lowest quintiles of the Paleolithic and Mediterranean diet scores were 0.61 (95% CI: 0.36, 1.05; P-trend = 0.06) and 0.71 (95% CI: 0.42, 1.20; P-trend = 0.01), respectively, for a higher hsCRP concentration, and 0.51 (95% CI: 0.27, 0.95; P-trend 0.01) and 0.39 (95% CI: 0.21, 0.73; P-trend = 0.01), respectively, for a higher F2-isoprostane concentration.

CONCLUSION

These findings suggest that diets that are more Paleolithic- or Mediterranean-like may be associated with lower levels of systemic inflammation and oxidative stress in humans.

An update of the WCRF/AICR systematic literature review on esophageal and gastric cancers and citrus fruits intake

Purpose

The 2007 World Cancer Research Fund/American Institute for Cancer Research expert report concluded that foods containing vitamin C probably protect against esophageal cancer and fruits probably protect against gastric cancer. Most of the previous evidence was from case–control studies, which may be affected by recall and selection biases. More recently, several cohort studies have examined these associations. We conducted a systematic literature review of prospective studies on citrus fruits intake and risk of esophageal and gastric cancers.

Methods

PubMed was searched for studies published until 1 March 2016. We calculated summary relative risks and 95 % confidence intervals (95 % CI) using random-effects models.

Results

With each 100 g/day increase of citrus fruits intake, a marginally significant decreased risk of esophageal cancer was observed (summary RR 0.86, 95 % CI 0.74–1.00, 1,057 cases, six studies). The associations were similar for squamous cell carcinoma (RR 0.87, 95 % CI 0.69–1.08, three studies) and esophageal adenocarcinoma (RR 0.93, 95 % CI 0.78–1.11, three studies). For gastric cancer, the nonsignificant inverse association was observed for gastric cardia cancer (RR 0.75, 95 % CI 0.55–1.01, three studies), but not for gastric non-cardia cancer (RR 1.02, 95 % CI 0.90–1.16, four studies). Consistent summary inverse associations were observed when comparing the highest with lowest intake, with statistically significant associations for esophageal (RR 0.77, 95 % CI 0.64–0.91, seven studies) and gastric cardia cancers (RR 0.62, 95 % CI 0.39–0.99, three studies).

Conclusions

Citrus fruits may decrease the risk of esophageal and gastric cardia cancers, but further studies are needed.

Electronic supplementary material

The online version of this article (doi:10.1007/s10552-016-0755-0) contains supplementary material, which is available to authorized users.

Identification QTLs Controlling Genes for Se Uptake in Lentil Seeds

Lentil (Lens culinaris Medik.) is an excellent source of protein and carbohydrates and is also rich in essential trace elements for the human diet. Selenium (Se) is an essential micronutrient for human health and nutrition, providing protection against several diseases and regulating important biological systems. Dietary intake of 55 μg of Se per day is recommended for adults, with inadequate Se intake causing significant health problems. The objective of this study was to identify and map quantitative trait loci (QTL) of genes controlling Se accumulation in lentil seeds using a population of 96 recombinant inbred lines (RILs) developed from the cross “PI 320937” × “Eston” grown in three different environments for two years (2012 and 2013). Se concentration in seed varied between 119 and 883 μg/kg. A linkage map consisting of 1,784 markers (4 SSRs, and 1,780 SNPs) was developed. The map spanned a total length of 4,060.6 cM, consisting of 7 linkage groups (LGs) with an average distance of 2.3 cM between adjacent markers. Four QTL regions and 36 putative QTL markers, with LOD scores ranging from 3.00 to 4.97, distributed across two linkage groups (LG2 and LG5) were associated with seed Se concentration, explaining 6.3–16.9% of the phenotypic variation.

Dietary Total Antioxidant Capacity and Colorectal Cancer in the Italian EPIC Cohort

Background

Colorectal cancer is the third most common cancer worldwide. Diet has been hypothesized as involved in colorectal cancer etiology, but few studies on the influence of total dietary antioxidant intake on colorectal cancer risk have been performed.

Methods

We investigated the association between colorectal cancer risk and the total antioxidant capacity (TAC) of the diet, and also of intake of selected antioxidants, in 45,194 persons enrolled in 5 centers (Florence, Naples, Ragusa, Turin and Varese) of the European Prospective Investigation into Cancer and Nutrition (EPIC) Italy study. TAC was estimated by the Trolox equivalent antioxidant capacity (TEAC) assay. Hazard ratios (HRs) for developing colorectal cancer, and colon and rectal cancers separately, adjusted for confounders, were estimated for tertiles of TAC by Cox modeling, stratifying by center.

Results

Four hundred thirty-six colorectal cancers were diagnosed over a mean follow-up of 11.28 years. No significant association between dietary TAC and colorectal cancer incidence was found. However for the highest category of TAC compared to the lowest, risk of developing colon cancer was lower (HR: 0.63; 95% CI: 0.44–0.89, P trend: 0.008). By contrast, increasing TAC intake was associated with significantly increasing risks of rectal cancer (2nd tertile HR: 2.09; 95%CI: 1.19–3.66; 3rd tertile 2.48 95%CI: 1.32–4.66; P trend 0.007). Intakes of vitamin C, vitamin E, and ß-carotene were not significantly associated with colorectal cancer risk.

Conclusions

Further prospective studies are needed to confirm the contrasting effects of high total antioxidant intake on risk of colon and rectal cancers.

Efficacy of Vitamin C Supplements in Prevention of Cancer: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Previous randomized controlled trials (RCTs) have reported inconsistent findings regarding the association between vitamin C supplementation and the risk of cancer.

METHODS

We performed a meta-analysis of RCTs to investigate the efficacy of vitamin C supplements for prevention of cancer. We searched the PubMed, EMBASE, and Cochrane Library databases in November 2014 using common keywords related to vitamin C supplements and cancer.

RESULTS

Among 785 articles, a total of seven trials were identified, which included 62,619 participants; 31,326 and 31,293 were randomized to vitamin C supplementation and control or placebo groups, respectively, which were included in the final analysis. A fixed-effects meta-analysis of all seven RCTs revealed no significant association between vitamin C supplementation and cancer (relative risk, 1.00; 95% confidence intervals, 0.95-1.05). Similarly, subgroup meta-analysis by dose of vitamin C administered singly or in combination with other supplements, follow-up period, methodological quality, cancer mortality, gender, smoking status, country, and type of cancer also showed no efficacy of vitamin C supplementation for cancer prevention.

CONCLUSION

This meta-analysis shows that there is no evidence to support the use of vitamin C supplements for prevention of cancer.

Vitamin E supplementation and mortality in healthy people: a meta-analysis of randomised controlled trials

PURPOSE

To evaluate the effect of oral vitamin E supplementation on all-cause mortality in apparently healthy people.

METHODS

A systematic review and meta-analysis was conducted on randomised controlled trials (RCTs) with ≥ 6 months of follow up investigating the effect of vitamin E supplementation on healthy adults in developed countries. Electronic databases (MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials) and reference lists of trial reports were searched for RCTs published between 1966 and June 2012. Three investigators assessed eligibility of identified trials. Disagreements were resolved by consensus. Two investigators independently extracted data according to the criteria.

RESULTS

There were 18 RCTs identified with 142,219 apparently healthy participants (71,116 in vitamin E intervention groups and 71,103 in control groups) that were included in the final analysis. Fixed effect and random effects analysis of the 18 trials revealed that supplementation with vitamin E was not associated with all-cause mortality (relative risk 1.01, 95% confidence interval 0.97 - 1.05, p = 0.65). Subgroup analyses by type of vitamin E (natural or synthetic), dose or duration of exposure, study design or quality, and pre-specified mortality outcome showed no association with all-cause mortality.

CONCLUSIONS

The evidence from pooled analysis of 18 randomised controlled trials undertaken in apparently healthy people shows no effect of vitamin E supplementation at a dose of 23-800 IU/day on all-cause mortality.

Oxidative balance scores and risk of incident colorectal cancer in a US prospective cohort study

Although oxidative stress is implicated in colorectal carcinogenesis, human studies on associations of individual prooxidants and antioxidants with colorectal cancer (CRC) have been inconclusive. We incorporated individual environmental factors known to affect oxidative stress into 4 oxidative balance scores (OBS) and investigated their associations with CRC in the Cancer Prevention Study II Nutrition Cohort. During 1999-2009, a total of 1,109 incident CRC cases were identified among 80,063 participants in the Nutrition Cohort who had completed detailed questionnaires. Four OBS with different weighting methods (equal weights, literature review-based, a posteriori data-based, and weights based on Bayesian analysis) were created by combining 16 dietary and nondietary lifestyle factors. Higher values for all 4 OBS, representing more antioxidant exposures than prooxidant exposures, were associated with 41%-53% lower risks of CRC; for example, the relative risk for the highest OBS quartile versus the lowest in the Bayesian analysis was 0.50 (95% confidence interval: 0.41, 0.61). The associations were more modest when OBS was restricted to either dietary or nondietary components. These results, obtained using comprehensive summary measures of oxidative balance-especially considering the similarity of the findings derived using the different weighting methods-support the hypothesis that a predominance of antioxidant lifestyle exposures (both dietary and nondietary) over prooxidant lifestyle exposures reduces risk of CRC.

Tacrolimus and mycophenolate mofetil associations

Gastrointestinal risk factors after organ transplantation are prevalent, due to the chronic use of immunosuppressant. The immunosuppressive drugs such as tacrolimus/mycophenolate mofetil (TAC/MMF) association are the most commonly used therapy. TAC and MMF have been implicated in gastrotoxicity, but their direct effects, alone and combined, on intestinal cells are not completely elucidated. This study investigated the effect of TAC and MMF alone and combined on human colon carcinoma cells. Our results demonstrated that TAC and MMF individually inhibit clearly cells proliferation, enhanced free radicals, lipid peroxidation production, induced DNA lesions and reduced mitochondrial membrane potential. In this study, we also showed that the two molecules TAC and MMF combined at high concentrations amplified the cell damage. Furthermore, the TAC (5 µM) prevented cell death induced by MMF (half maximal inhibitory concentration (IC50)). Also, MMF (50 µM) induced cytoprotection in HCT116 cells against TAC (IC50) toxicity. Our findings provide additional evidence that oxidative damage is the major contribution of TAC and MMF combined toxicities. In fact, MMF and TAC exert a gastroprotective effect by modulating reactive oxygen species production. These data underscore the pleiotropic effect of TAC and MMF on HCT116 cells that play a preventive and critical role on intestinal function.

Vitamin intake reduce the risk of gastric cancer: meta-analysis and systematic review of randomized and observational studies

AIM

The association between vitamin intake and gastric cancer (GC) has been widely debated due to the relatively weak evidence. In this study, a meta-analysis of prospective and well designed observational studies were performed to explore this association.

METHODS

MEDLINE, Cochrane Library, and Sciencedirect were searched for studies of vitamin consumption and gastric cancer. This produced 47 relevant studies covering 1,221,392 human subjects. Random effects models were used to estimate summary relative risk (RR). Dose-response, subgroup, sensitivity, meta-regression, and publication bias analyses were conducted.

RESULTS

The RR of gastric cancer in the group with the highest vitamin intake was compared to that of the lowest intake group. Total vitamin intake was 0.78 (95% CI, 0.71-0.83). In 9 studies that individuals were given doses at least 4 times above the tolerable upper intake (UL) vitamins, the RR was 1.20 (95% CI, 0.99-1.44). However, in 17 studies that individuals received doses below the UL, the RR was 0.76 (95% CI, 0.68-0.86). Dose-response analysis was conducted on different increments in different types of vitamins (vitamin A: 1.5 mg/day, vitamin C: 100 mg/day, vitamin E: 10 mg/day) intake with a significant reduction in the risk of gastric cancer, respectively, 29% in vitamin A, 26% in vitamin C, and 24% in vitamin E.

CONCLUSION

This meta-analysis clearly demonstrated that low doses of vitamins can significantly reduce the risk of GC, especially vitamin A, vitamin C, vitamin E.

Dietary factors and the risk of glaucoma: a review

Glaucoma is an optic neuropathy characterized by a progressive typical pattern of optic neurodegeneration and visual field loss. A relatively high proportion of glauctomatous individuals admit to interest in dietary modification in an attempt to manage their disease. Heavy caffeine consumption appears to have a transient effect on increasing intraocular pressure (IOP). This effect may be clinically insignificant for nonglaucomatous individuals, but the association warrants clinical consideration in those with the disease. Studies investigating the relationship between self-reported antioxidant intake and risk of glaucomatous disease have reported conflicting results. Preliminary studies investigating the relationship between self-reported glaucoma diagnosis and consumption of the oxidants calcium and iron suggest a possible relationship indicating increased risk of the disease with increased consumption of these dietary factors. Initial reports in the literature suggest a potential role for dietary modification in the treatment of glaucomatous optic neuropathy. Further study, with randomized controlled trials, may be necessary to further characterize these relationships.

Diet, Helicobacter pylori strain-specific infection, and gastric cancer risk among Chinese men

Evidence for the association of diet and gastric cancer is equivocal, and the majority of previous studies have not evaluated the interaction of diet and infection with Helicobacter pylori, the leading risk factor for gastric cancer. We examined these associations among 226 cases and 451 controls nested within a prospective cohort. Dietary intakes were calculated from validated food frequency questionnaires. Blood levels of 15 antibodies to Helicobacter pylori proteins were assessed using multiplex serology. Odds ratios (ORs) were calculated using logistic regression. Among individuals infected with high-risk Helicobacter pylori (sero-positivity to 5-6 virulent H. pylori proteins), increasing intake of red meat, heme iron, and sodium increased risk (comparing highest tertile to lowest: ORs [95% confidence interval {CI}]: 1.85 [1.01-3.40]; 1.95 [1.06-3.57]; and 1.76 [0.91-3.43], respectively) while increasing intake of fruit decreased gastric cancer risk (comparing highest tertile of intake to lowest: OR [95% CI]: 0.52 [0.28-0.94]). No associations of diet with risk were found among individuals infected with low-risk H. pylori (P for interaction for red meat and sodium: 0.02 and 0.01, respectively). In this population with over 90% prevalence of CagA-positive H. pylori infection, categorizing individuals using H. pylori multiplex serology may identify individuals for whom a diet intervention may be effective.

The antioxidant paradox: less paradoxical now?

The term 'antioxidant paradox' is often used to refer to the observation that oxygen radicals and other reactive oxygen species are involved in several human diseases, but giving large doses of dietary antioxidant supplements to human subjects has, in most studies, demonstrated little or no preventative or therapeutic effect. Why should this be? First, the role of reactive oxygen species in the origin and/or progression of most human diseases is unclear, although they are probably important in cancer, neurodegenerative diseases and perhaps some others. Second, the endogenous antioxidant defences in the human body are complex, interlocking and carefully regulated. The body's 'total antioxidant capacity' seems unresponsive to high doses of dietary antioxidants, so that the amount of oxidative damage to key biomolecules is rarely changed. Indeed, manipulation of endogenous antioxidant levels (e.g. by supplying weak pro-oxidants) may be a more useful approach to treatment and prevention of diseases in which reactive oxygen species are important than is consumption of large doses of dietary antioxidants.

Dietary lifestyle and colorectal cancer onset, recurrence, and survival: myth or reality?

BACKGROUND AND PURPOSE

Interest in the possibility that diet might help to reduce the risk of colorectal cancer dates back to 1970 based on both the large variation in rates of specific cancers in different countries and the impressive changes observed in the incidence of cancer in migrants from low- to high-risk areas. Here, we report the state of art of literature data about this topic.

METHODS

Three sections have been separately considered: chemoprevention of first tumor onset, chemoprevention of recurrence after surgery, and chemoprevention of polyp recurrence in the course of the follow-up of subjects with elevated risk. A particular attention has been pointed to dietary factors and survival, whose relevance is showing a growing interest.

RESULTS

The relationship between diet and colorectal cancer has been extensively studied about the onset, sometimes with controversial results. Its influence on recurrence and survival has been examined in only few studies.

CONCLUSIONS

Literature data are convincing for a protective role on the onset of preneoplastic and neoplastic lesions for some foods such as fibers, vitamin A and D, folic acid, calcium, antioxidants, and promising perspectives for some substances such as phyto-estrogens. Less evidence-based data are available on the possibility to avoid the recurrence of the disease or to affect its mortality with dietary habits. Future perspectives will be directed be not only to identify new dietary style able to prevent the onset of neoplastic lesion of the colon but also to realize an effective chemoprevention.

An evidence-based systematic review of vitamin A by the natural standard research collaboration

An evidence-based systematic review of vitamin A by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated and reproducible grading rationale. This paper includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

A prescribed Chinese herbal medicine improves glucose profile and ameliorates oxidative stress in Goto-Kakisaki rats fed with high fat diet

Oxidative stress (OS) plays a role in hyperglycemia induced islet β cell dysfunction, however, studies on classic anti-oxidants didn’t show positive results in treating diabetes. We previously demonstrated that the prescribed Chinese herbal medicine preparation “Qing Huo Yi Hao” (QHYH) improved endothelial function in type 2 diabetic patients. QHYH protected endothelial cells from high glucose-induced damages by scavenging superoxide anion and reducing production of reactive oxygen species. Its active component protected C2C12 myotubes against palmitate-induced oxidative damage and mitochondrial dysfunction. In the present study, we investigated whether QHYH protected islet β cell function exacerbated by high fat diet (HFD) in hyperglycemic GK rats. 4-week-old male rats were randomly divided into high HFD feeding group (n = 20) and chow diet feeding group (n = 10). Each gram of HFD contained 4.8 kcal of energy, 52% of which from fat. Rats on HFD were further divided into 2 groups given either QHYH (3 ml/Kg/d) or saline through gastric tube. After intervention, serum glucose concentrations were monitored; IPGTTs were performed without anesthesia on 5 fasting rats randomly chosen from each group on week 4 and 16. Serum malondialdehyde (MDA) concentrations and activities of serum antioxidant enzymes were measured on week 4 and 16. Islet β cell mass and OS marker staining was done by immunohistochemistry on week 16. QHYH prevented the exacerbation of hyperglycemia in HFD feeding GK rats for 12 weeks. On week 16, it improved the exacerbated glucose tolerance and prevented the further loss of islet β cell mass induced by HFD. QHYH markedly decreased serum MDA concentration, increased serum catalase (CAT) and SOD activities on week 4. However, no differences of serum glucose concentration or OS were observed on week 16. We concluded that QHYH decreased hyperglycemia exacerbated by HFD in GK rats by improving β cell function partly via its antioxidant effect.

Diet and colorectal cancer risk and survival

SUMMARY Unhealthy dietary and other lifestyle factors account for 20–45% of all colorectal cancer cases. Being overweight or obese, having a high intake of red and processed meat and alcohol increase the risk of colorectal cancer, while a high intake of dairy products, fruits and vegetables, foods containing dietary fiber and being physically active lower the risk of colorectal cancer. There are only a limited number of studies available on diet and outcomes in colorectal cancer survivors. Most of these studies are retrospective in nature, and are small in size, which makes it difficult to draw conclusions. However, the available studies to date putatively suggest that lifestyle factors lowering the risk of colorectal cancer are also beneficial for cancer survivors.

Disease progression mediated by egr-1 associated signaling in response to oxidative stress

When cellular reducing enzymes fail to shield the cell from increased amounts of reactive oxygen species (ROS), oxidative stress arises. The redox state is misbalanced, DNA and proteins are damaged and cellular transcription networks are activated. This condition can lead to the initiation and/or to the progression of atherosclerosis, tumors or pulmonary hypertension; diseases that are decisively furthered by the presence of oxidizing agents. Redox sensitive genes, like the zinc finger transcription factor early growth response 1 (Egr-1), play a pivotal role in the pathophysiology of these diseases. Apart from inducing apoptosis, signaling partners like the MEK/ERK pathway or the protein kinase C (PKC) can activate salvage programs such as cell proliferation that do not ameliorate, but rather worsen their outcome. Here, we review the currently available data on Egr-1 related signal transduction cascades in response to oxidative stress in the progression of epidemiologically significant diseases. Knowing the molecular pathways behind the pathology will greatly enhance our ability to identify possible targets for the development of new therapeutic strategies.

Design and baseline characteristics of participants in a phase III randomized trial of celecoxib and selenium for colorectal adenoma prevention

COX inhibitors reduce colorectal adenoma recurrence by up to 45% and selenium supplementation may prevent colorectal cancer. Following colonoscopic adenoma resection, 1,600 men and women, ages 40 to 80 years, were randomized to celecoxib (400 mg daily), a selective COX-2 inhibitor, and/or selenium (200 μg daily as selenized yeast), or double placebo. The trial was initiated in November 2001. The primary trial endpoint is adenoma recurrence in each intervention group compared with placebo, as determined by surveillance colonoscopy conducted three to five years after baseline. Randomization was stratified by use of low-dose aspirin (81 mg) and clinic site. Following reports of cardiovascular toxicity associated with COX-2 inhibitors, the celecoxib arm was discontinued in December 2004 when 824 participants had been randomized. Accrual continued with randomization to selenium alone or placebo. Randomization of the originally planned cohort (n = 1,621) was completed in November 2008. A further 200 patients with one or more advanced adenomas (denoting increased risk for colorectal cancer) were accrued to enhance statistical power for determining intervention efficacy in this higher-risk subgroup. Accrual of the total cohort (n = 1,824) was completed in January 2011. Baseline cohort characteristics include: mean age 62.9 years; 65% male; body mass index (BMI) 29.1 ± 5.1; 47% taking low-dose aspirin while on trial; 20% with three or more adenomas; and 38% with advanced adenomas. Intervention effects on adenoma recurrence will be determined, and their modification by genetic background and baseline selenium level. The effect of selenium supplementation on risk for type II diabetes will also be reported.

Adverse effects of antioxidative vitamins

High doses of synthetic antioxidative vitamins: A, E, C and β-carotene are often used on long-term basis in numerous preventive and therapeutic medical applications. Instead of expected health effects, the use of those vitamins may however lead to cases of hypervitaminosis and even to intoxication. The article points out main principles of safety which are to be observed during supplementation with antioxidative vitamins. Toxic effects resulting from erroneous administration of high doses of those substances on organs and systems of the organism are also discussed. Attention is drawn to interactions of antioxidative vitamins with concomitantly used drugs, as well as intensification of adverse effects caused by various exogenous chemical factors. Moreover, the article presents the evaluation of supplementation with these vitamins, which was performed in large studies.

The spatial distribution of LGR5+ cells correlates with gastric cancer progression

In this study we tested the prevalence, histoanatomical distribution and tumour biological significance of the Wnt target protein and cancer stem cell marker LGR5 in tumours of the human gastrointestinal tract. Differential expression of LGR5 was studied on transcriptional (real-time polymerase chain reaction) and translational level (immunohistochemistry) in malignant and corresponding non-malignant tissues of 127 patients comprising six different primary tumour sites, i.e. oesophagus, stomach, liver, pancreas, colon and rectum. The clinico-pathological significance of LGR5 expression was studied in 100 patients with gastric carcinoma (GC). Non-neoplastic tissue usually harboured only very few scattered LGR5⁺ cells. The corresponding carcinomas of the oesophagus, stomach, liver, pancreas, colon and rectum showed significantly more LGR5⁺ cells as well as significantly higher levels of LGR5-mRNA compared with the corresponding non-neoplastic tissue. Double staining experiments revealed a coexpression of LGR5 with the putative stem cell markers CD44, Musashi-1 and ADAM17. Next we tested the hypothesis that the sequential changes of gastric carcinogenesis, i.e. chronic atrophic gastritis, intestinal metaplasia and invasive carcinoma, are associated with a reallocation of the LGR5⁺ cells. Interestingly, the spatial distribution of LGR5 changed: in non-neoplastic stomach mucosa, LGR5⁺ cells were found predominantly in the mucous neck region; in intestinal metaplasia LGR5⁺ cells were localized at the crypt base, and in GC LGR5⁺ cells were present at the luminal surface, the tumour centre and the invasion front. The expression of LGR5 in the tumour centre and invasion front of GC correlated significantly with the local tumour growth (T-category) and the nodal spread (N-category). Furthermore, patients with LGR5⁺ GCs had a shorter median survival (28.0±8.6 months) than patients with LGR5⁻ GCs (54.5±6.3 months). Our results show that LGR5 is differentially expressed in gastrointestinal cancers and that the spatial histoanatomical distribution of LGR5⁺ cells has to be considered when their tumour biological significance is sought.

Fifteen-year effects of Helicobacter pylori, garlic, and vitamin treatments on gastric cancer incidence and mortality

In the Shandong Intervention Trial, 2 weeks of antibiotic treatment for Helicobacter pylori reduced the prevalence of precancerous gastric lesions, whereas 7.3 years of oral supplementation with garlic extract and oil (garlic treatment) or vitamin C, vitamin E, and selenium (vitamin treatment) did not. Here we report 14.7-year follow-up for gastric cancer incidence and cause-specific mortality among 3365 randomly assigned subjects in this masked factorial placebo-controlled trial. Conditional logistic regression was used to estimate the odds of gastric cancer incidence, and the Cox proportional hazards model was used to estimate the relative hazard of cause-specific mortality. All statistical tests were two-sided. Gastric cancer was diagnosed in 3.0% of subjects who received H pylori treatment and in 4.6% of those who received placebo (odds ratio = 0.61, 95% confidence interval = 0.38 to 0.96, P = .032). Gastric cancer deaths occurred among 1.5% of subjects assigned H pylori treatment and among 2.1% of those assigned placebo (hazard ratio [HR] of death = 0.67, 95% CI = 0.36 to 1.28). Garlic and vitamin treatments were associated with non-statistically significant reductions in gastric cancer incidence and mortality. Vitamin treatment was associated with statistically significantly fewer deaths from gastric or esophageal cancer, a secondary endpoint (HR = 0.51, 95% CI = 0.30 to 0.87; P = .014).

American Cancer Society Guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity

The American Cancer Society (ACS) publishes Nutrition and Physical Activity Guidelines to serve as a foundation for its communication, policy, and community strategies and, ultimately, to affect dietary and physical activity patterns among Americans. These Guidelines, published approximately every 5 years, are developed by a national panel of experts in cancer research, prevention, epidemiology, public health, and policy, and they reflect the most current scientific evidence related to dietary and activity patterns and cancer risk. The ACS Guidelines focus on recommendations for individual choices regarding diet and physical activity patterns, but those choices occur within a community context that either facilitates or creates barriers to healthy behaviors. Therefore, this committee presents recommendations for community action to accompany the 4 recommendations for individual choices to reduce cancer risk. These recommendations for community action recognize that a supportive social and physical environment is indispensable if individuals at all levels of society are to have genuine opportunities to choose healthy behaviors. The ACS Guidelines are consistent with guidelines from the American Heart Association and the American Diabetes Association for the prevention of coronary heart disease and diabetes, as well as for general health promotion, as defined by the 2010 Dietary Guidelines for Americans and the 2008 Physical Activity Guidelines for Americans.

Dietary micronutrients and gastric cancer: hospital based study

The association between micronutrients and gastric cancer is still unclear. The aim of this study is to determine the relationship between dietary intake of micronutrients and risk for gastric cancer. We used data from hospital-based case control study conducted at Clinical Centre Nis (Serbia) from 2005 and 2006. Patients (n=102) with first histologically confirmed gastric cancer and matched non-cancer patients (controls, n=204) were interviewed using structured questionnaire and FFQ (Food frequency questionnaire). Multivariate logistic regression analysis showed a significant positive association between gastric cancer and dietary intake of sodium (OR=6.22; 95%CI 1.99–7.86), but a significant negative association between potassium (OR 0.01; 95%CI 0.00–0.08), iron (OR 0.05; 95%CI 0.01–0.56), vitamin C (OR 0.05; 95%CI 0.01–0.38), vitamin E (OR 0.04; 95%CI 0.01–0.29) and niacin (OR 0.07; 95%CI 0.00–0.38) dietary intake. Intake of phosphorus, calcium, magnesium, zinc, retinol, β carotene, tiamin, vitamin B6, and folic acid was not significantly related to gastric cancer risk.

In conclusion, we found that a dietary pattern of high consumption of antioxidants (vitamin C, vitamin E, niacin), iron and potassium and low consumption of foods that are sources of sodium, decreased risk for gastric cancer. Our results require confirmation in future studies.

Clinical trials of antioxidants as cancer prevention agents: past, present, and future

The purpose of this review is to summarize the most important human clinical trials of antioxidants as cancer prevention agents conducted to date, provide an overview of currently ongoing studies, and discuss future steps needed to advance research in this field. To date there have been several large (at least 7000 participants) trials testing the efficacy of antioxidant supplements in preventing cancer. The specific agents (diet-derived direct antioxidants and essential components of antioxidant enzymes) tested in those trials included β-carotene, vitamin E, vitamin C, selenium, retinol, zinc, riboflavin, and molybdenum. None of the completed trials produced convincing evidence to justify the use of traditional antioxidant-related vitamins or minerals for cancer prevention. Our search of ongoing trials identified six projects at various stages of completion. Five of those six trials use selenium as the intervention of interest delivered either alone or in combination with other agents. The lack of success to date can be explained by a variety of factors that need to be considered in the next generation research. These factors include lack of good biological rationale for selecting specific agents of interest; limited number of agents tested to date; use of pharmacological, rather than dietary, doses; and insufficient duration of intervention and follow-up. The latter consideration underscores the need for alternative endpoints that are associated with increased risk of neoplasia (i.e., biomarkers of risk), but are detectable prior to tumor occurrence. Although dietary antioxidants are a large and diverse group of compounds, only a small proportion of candidate agents have been tested. In summary, the strategy of focusing on large high-budget studies using cancer incidence as the endpoint and testing a relatively limited number of antioxidant agents has been largely unsuccessful. This lack of success in previous trials should not preclude us from seeking novel ways of preventing cancer by modulating oxidative balance. On the contrary, the well demonstrated mechanistic link between excessive oxidative stress and carcinogenesis underscores the need for new studies. It appears that future large-scale projects should be preceded by smaller, shorter, less expensive biomarker-based studies that can serve as a link from mechanistic and observational research to human cancer prevention trials. These relatively inexpensive studies would provide human experimental evidence for the likely efficacy, optimum dose, and long-term safety of the intervention of interest that would then guide the design of safe, more definitive large-scale trials.

Selenium and other antioxidants for chemoprevention of gastrointestinal cancers

Antioxidants such as selenium, vitamin E and C and carotenoids have been hypothesized as chemopreventive agents for several cancers. In the current review, we evaluate the results of epidemiological and interventional studies and summarize current knowledge of the prevention potential of the antioxidants, specific to gastrointestinal cancers. While early studies based on animal models and cell lines showed promise for antioxidants as chemopreventive agents for several gastrointestinal cancers, results from epidemiological studies and randomized trials do not support this promise. One large randomized trial, conducted in a region with widespread nutritional deficiency, showed that antioxidant use may confer protection against gastrointestinal cancers. However, this result has not been replicated in other epidemiological studies or the 10 other randomized trials conducted in developed Western countries. Overall, currently there is no evidence that antioxidants are protective against gastrointestinal cancers in populations whose members are replete in antioxidant intake.

Hepato-biliary clinical trials and their inclusion in the Cochrane Hepato-Biliary Group register and reviews

BACKGROUND AND AIMS

The Cochrane Hepato-Biliary Group (CHBG) is one of the 52 collaborative review groups within The Cochrane Collaboration. The activities of the CHBG focus on collecting hepato-biliary randomized clinical trials (RCT) and controlled clinical trials (CCT), and including them in systematic reviews with meta-analyses of the trials. In this overview, we present the growth of The CHBG Controlled Trials Register, as well as the systematic reviews that have been produced since March 1996.

RESULTS

The CHBG register includes almost 11,000 RCT and 700 CCT publications. The earliest RCT in the register were published in 1955, and the earliest CCT in 1945. From 1945 to 1980, there were less than 100 publications each year. From 1981 to 1997, their number increased from over 100 to 600 a year. After 1997, the number of publications seems to have been decreasing. The CHBG has published 199 protocols for systematic reviews and 107 systematic reviews through to August 2009 in which 21% of the RCT and CCT were included. The CHBG reviews have been cited approximately 1200 times.

CONCLUSIONS

A large amount of work has been carried out since 1996. However, there is still much to do, as the CHBG register contains a great number of RCT and CCT on topics that have not yet been systematically reviewed.

Antioxidant supplements for liver diseases

BACKGROUND

Several liver diseases have been associated with oxidative stress. Accordingly, antioxidants have been suggested as potential therapeutics for various liver diseases. The evidence supporting these suggestions is equivocal.

OBJECTIVES

To assess the benefits and harms of antioxidant supplements for patients with liver diseases.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to January 2011. We scanned bibliographies of relevant publications and asked experts and pharmaceutical companies for additional trials.

SELECTION CRITERIA

We considered for inclusion randomised trials that compared antioxidant supplements (beta-carotene, vitamin A, C, E, and selenium) versus placebo or no intervention for autoimmune liver diseases, viral hepatitis, alcoholic liver disease, and cirrhosis (any aetiology).

DATA COLLECTION AND ANALYSIS

Four authors independently selected trials for inclusion and extracted data. Outcome measures were all-cause mortality, liver-related mortality, liver-related morbidity, biochemical indices at maximum follow-up in the individual trials as well as adverse events, quality-of-life measures, and cost-effectiveness. For patients with hepatitis B or C we also considered end of treatment and sustained virological response. We conducted random-effects and fixed-effect meta-analyses. Results were presented as relative risks (RR) or mean differences (MD), both with 95% confidence intervals (CI).

MAIN RESULTS

Twenty randomised trials with 1225 participants were included. The trials assessed beta-carotene (3 trials), vitamin A (2 trials), vitamin C (9 trials), vitamin E (15 trials), and selenium (8 trials). The majority of the trials had high risk of bias and showed heterogeneity. Overall, the assessed antioxidant supplements had no significant effect on all-cause mortality (relative risk [RR] 0.84, 95% confidence interval [CI] 0.60 to 1.19, I(2) = 0%), or liver-related mortality (RR 0.89, 95% CI 0.39 to 2.05, I(2) = 37%). Stratification according to the type of liver disease did not affect noticeably the results. Antioxidant supplements significantly increased activity of gamma glutamyl transpeptidase (MD 24.21 IU/l, 95% CI 6.67 to 41.75, I(2) = 0%).

AUTHORS' CONCLUSIONS

We found no evidence to support or refute antioxidant supplements in patients with liver disease. Antioxidant supplements may increase liver enzyme activity.

Use of chemoprotectants in chemotherapy and radiation therapy: the challenges of selecting an appropriate agent

Chemoprotection refers to the protection from the toxicity of one chemical by the intervention of another. Conflicting preclinical and clinical reports make it difficult to either ignore or accept the use of chemoprotectants during cancer chemotherapy or radiotherapy. The selection of anticancer drugs depends on the type and stage of cancer development. However, very little attention has been paid to the selection of chemoprotectants. The answer to the use of chemoprotectants during cancer therapy lies in their appropriate selection in a case-specific and/or issue-specific manner. The need of the hour is to find better answers on the rationality of chemoprotectants selection during cancer therapy using cutting-edge science. In this commentary, we have presented few examples to justify our view-points.

Barrett's esophagus, esophageal and esophagogastric junction adenocarcinomas: the role of diet

Identification of modifiable risk factors is an attractive approach to primary prevention of esophageal adenocarcinoma (EAC) and esophagogastric junction adenocarcinoma (EGJAC). We conducted a review of the literature to investigate the association between specific dietary components and the risk of Barrett’s esophagus (BE), EAC and EGJAC, supposing diet might be a risk factor for these tumors. Consumption of meat and high-fat meals has been found positively associated with EAC and EGJAC. An inverse association with increased intake of fruit, vegetables and antioxidants has been reported but this association was not consistent across all studies reviewed. Few studies have examined the association between diet and BE. Additional research is needed to confirm the aforementioned association and clarify the mechanisms by which dietary components affect the risk of developing EAC and EGJAC. Future studies could advance our knowledge by emphasizing prospective designs to reduce recall bias, by using validated dietary intake questionnaires and biological measures and by considering important confounders such as gastro-esophageal reflux disease (GERD) symptoms, tobacco and alcohol use, biometrics, physical activity, and socioeconomic factors.