Antioxidant intake from diet and supplements and risk of digestive cancers in middle-aged adults: results from the prospective NutriNet-Santé cohort

Evaluating agreement between individual nutrition randomised controlled trials and cohort studies - a meta-epidemiological study

BACKGROUND

In nutrition research, randomised controlled trials (RCTs) and cohort studies provide complementary evidence. This meta-epidemiological study aims to evaluate the agreement of effect estimates from individual nutrition RCTs and cohort studies investigating a highly similar research question and to investigate determinants of disagreement.

METHODS

MEDLINE, Epistemonikos, and the Cochrane Database of Systematic Reviews were searched from January 2010 to September 2021. We matched individual RCTs to cohort studies based on population, intervention/exposure, comparator, and outcome (PI/ECO) characteristics. Two reviewers independently extracted study characteristics and effect estimates and rated the risk of bias using RoB2 and ROBINS-E. Agreement of matched RCTs/cohort studies was analysed by pooling ratio of risk ratios (RRR) and difference of (standardised) mean differences (DSMD).

RESULTS

We included 64 RCT/cohort study pairs with 4,136,837 participants. Regarding PI/ECO similarity, 20.3% pairs were "more or less identical", 71.9% "similar but not identical" and 7.8% "broadly similar". Most RCTs were classified as "low risk of bias" (26.6%) or with "some concerns" (65.6%); cohort studies were mostly rated with "some concerns" (46.6%) or "high risk of bias" (47.9%), driven by inadequate control of important confounding factors. Effect estimates across RCTs and cohort studies were in high agreement (RRR 1.00 (95% CI 0.91-1.10, n = 54); and DSMD - 0.26 (95% CI - 0.87-0.35, n = 7)). In meta-regression analyses exploring determinants of disagreements, risk-of-bias judgements tend to have had more influence on the effect estimate than "PI/ECO similarity" degree.

CONCLUSIONS

Effect estimates of nutrition RCTs and cohort studies were generally similar. Careful consideration and evaluation of PI/ECO characteristics and risk of bias is crucial for a trustworthy utilisation of evidence from RCTs and cohort studies.

Preeminent Terminator of Oxygen Free Radicals─Mineralized Reduced Water

Drinking water is an essential daily intake to hydrate the body. It is conceivable that water, when endowed with antioxidant properties, will be the most natural radical terminator surpassing conventional pill-based or food-derived antioxidants. However, current end-of-pipe purification of municipal water generally depletes minerals pivotal for antioxidant potency. To surmount this dilemma, we assemble a multistage and multifunctional water treatment system using various filter materials that dislodge contaminants, mineralize water and impart reductive attributes. The mineralized reduced water (MRW) generated by this system possesses an ideal antioxidant water quality with weak alkalinity, negative oxidation-reduction potential and rich minerals including calcium, magnesium, zinc and silicon. This water decreases oxidative products in vivo via counteracting reactive oxygen species and activating the endogenous antioxidant system governed by nuclear factor erythroid 2-related factor 2. Moreover, long-term intake of MRW effectively retards xenografted tumor growth without any discernible hematologic and organic toxicity. These findings portend enormous promise for MRW in the prevention and treatment of oxidative stress-related maladies and even antiaging.

Association between dietary vitamin C intake/blood level and risk of digestive system cancer: a systematic review and meta-analysis of prospective studies

Experimental studies have shown that vitamin C has anti-cancer effects, but previous meta-analyses have indicated that the role of vitamin C in digestive system cancers (DSCs) is controversial. In this study, a systematic review and meta-analysis of the relationship between dietary intake/plasma concentration of vitamin C and the risk of DSC was conducted, evaluating 32 prospective studies with 1 664 498 participants. Dose-response and subgroup analyses were also performed. Systematic literature searches were performed in PubMed, EMBASE and Web of Science databases until 9th September 2023. Vitamin C intake significantly reduced DSCs risk (RR = 0.88, 95% confidence interval (CI) 0.83 to 0.93). The subgroup analyses showed the risks of oral, pharyngeal, and esophageal (OPE) cancers (0.81, 0.72 to 0.93), gastric cancer (0.81, 0.68 to 0.95), and colorectal cancer (0.89, 0.82 to 0.98) were negatively correlated with vitamin C intake, and the effect of vitamin C was different between colon cancer (0.87, 0.77 to 0.97) and rectal cancer (1.00, 0.84 to 1.19). However, plasma vitamin C concentration was only inversely associated with gastric cancer risk (0.74, 0.59 to 0.92). Dose-response analysis revealed that 250 and 65 mg day-1 vitamin C intakes had the strongest protective effect against OPE and gastric cancers respectively. These estimates suggest that vitamin C intake could significantly reduce gastrointestinal cancer incidence, including OPE, gastric, and colon cancers. Plasma vitamin C has a significant reduction effect on the incidence of gastric cancer only, but additional large-scale clinical studies are needed to determine its impact on the incidence of DSCs.

Not all carotenoids can reduce the risk of gastric cancer: a systematic review with meta-analysis

BACKGROUND

Gastric cancer is characterized by high invasiveness, heterogeneity, and late diagnosis, leading to high incidence and mortality rates. It is a significant public health concern globally. Early prevention is crucial in reducing the occurrence of gastric cancer, and dietary prevention, particularly focusing on carotenoids, has been considered a convenient and effective approach. However, the association between carotenoid intake and gastric cancer incidence remains controversial.

METHODS

A systematic search was conducted in PubMed, Ovid Embase, Web of Science, and Cochrane databases from inception to January 5, 2023. Two reviewers independently screened search results, extracted relevant data, and evaluated study quality. Statistical analysis was performed using the "metan" command in STATA 16 software. Random-effects or fixed-effects models were chosen based on the magnitude of heterogeneity among studies.

RESULTS

This study included a total of 35 publications, consisting of 23 case-control studies and 12 cohort studies. Meta-analysis of case-control studies showed that alpha-carotene (OR = 0.71, 95% CI: 0.55-0.92), beta-carotene (OR = 0.62, 95% CI: 0.53-0.72), and lutein (OR = 0.82, 95% CI: 0.69-0.97) significantly reduced the risk of gastric cancer, while beta-cryptoxanthin (OR = 0.88, 95% CI: 0.75-1.04) and lycopene (OR = 0.86, 95% CI: 0.73-1.00) showed no significant correlation. Meta-analysis of cohort studies indicated no significant associations between any of the five carotenoids and gastric cancer incidence (alpha-carotene: RR = 0.81, 95% CI: 0.54-1.23; beta-carotene: RR = 0.86, 95% CI: 0.64-1.16; beta-cryptoxanthin: RR = 0.86, 95% CI: 0.64-1.16; lutein: RR = 0.94, 95% CI: 0.69-1.29; lycopene: RR = 0.89, 95% CI: 0.69-1.14).

CONCLUSIONS

The relationship between carotenoids and gastric cancer incidence may vary depending on the type of study conducted. Considering that evidence from cohort studies is generally considered stronger than evidence from case-control studies, and high-quality randomized controlled trials show no significant association between carotenoids and gastric cancer incidence, current evidence does not support the supplementation of carotenoids for gastric cancer prevention. Further targeted research is needed to explore the association between the two.

Interaction between vitamin E intake and a COMT gene variant on colorectal cancer risk among Korean adults: a case-control study

OBJECTIVES

Previous human trials have not supported the anticarcinogenic effect of vitamin E despite biological plausibility and considerable epidemiological evidence. A possible explanation for this inconsistency is the interactive effect of the catechol-O-methyltransferase (COMT) gene and supplemental vitamin E on cancer. We examined whether a COMT gene variant modulates the effect of dietary vitamin E intake on colorectal cancer (CRC) risk.

METHODS

In this case-control study of Korean adults (975 cases and 975 age- and sex-matched controls), dietary vitamin E density (mg/1,000 kcal) was measured using a semiquantitative food frequency questionnaire, COMT single nucleotide polymorphism (SNP) rs740603 (A>G) was genotyped, and CRC was verified histologically. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression models with adjustments for potential confounders.

RESULTS

Higher vitamin E density was associated with a lower risk of CRC (highest vs. lowest quartiles: OR, 0.72; 95% CI, 0.55 to 0.96; p-for-trend=0.002). When stratified by COMT SNP rs740603 genotype, the inverse association between vitamin E density and CRC risk was confined to those with at least 1 A allele (≥median vs.

CONCLUSIONS

Our findings support a role for a genetic polymorphism in COMT in modifying the association between dietary vitamin E intake and CRC.

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Key Words

• Case-control studies
• Catechol-O-methyltransferase
• Colorectal cancer
• Gene-environment interaction
• Single nucleotide polymorphism
• Vitamin E

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MESH Headings

• Adult
• Humans
• Catechol O-Methyltransferase/genetics
• Case-Control Studies
• Polymorphism, Single Nucleotide
• Vitamin E
• Logistic Models
• Colorectal Neoplasms/epidemiology
• Colorectal Neoplasms/genetics
• Republic of Korea/epidemiology
• Risk Factors

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Grants

• National Research Foundation of Korea
• 2021R1A6A3A01087058 Ministry of Education
• 2021R1A2C2008439 Ministry of Science and ICT

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Affiliation(s)

Shinyoung Jun Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea
Madhawa Gunathilake Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea
Jeonghee Lee Department of Cancer Biomedical Science, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea
Jae Hwan Oh Center for Colorectal Cancer, National Cancer Center, Goyang, Korea
Hee Jin Chang Center for Colorectal Cancer, National Cancer Center, Goyang, Korea
Dae Kyung Sohn Center for Colorectal Cancer, National Cancer Center, Goyang, Korea
Aesun Shin Department of Preventive Medicine, Seoul National University College of Medicine, Seoul, Korea Cancer Research Institute, Seoul National University, Seoul, Korea
Jeongseon Kim Department of Cancer, AI & Digital Health, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Korea

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Association between Dietary and Supplemental Antioxidants Intake and Lung Cancer Risk: Evidence from a Cancer Screening Trial

Previous studies provided inconsistent results on the effects of antioxidant nutrient intake on lung cancer prevention. We aimed to evaluate the association between antioxidant consumption from food and supplemental sources and lung cancer incidence. Data were obtained from the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial. A total of 98,451 participants were included in the data analysis. We used a multivariable Cox proportional hazards regression model to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between antioxidant intake and lung cancer risk. Dose-response assessments for individual nutrients were conducted. We also selected the model for the best combination of antioxidants for reducing lung cancer risk using machine learning methods. After the median follow-up of 12.2 years, 1642 new cases were identified. Intake of the calculated HRs indicated a trend for a higher quartile of food-based Composite Dietary Antioxidant Index (fCDAI) associated with a lower lung cancer risk after adjusting for covariates (HR_Q4vs.Q1 = 0.64, 95% CI: 0.52, 0.79; P for trend < 0.001). Protective effects of dietary antioxidant intake were observed across all individual antioxidant micronutrients except magnesium. Random forests model suggested the dietary intake group of α-carotene, magnesium, vitamin C, vitamin E, lycopene, selenium, lutein, and zeaxanthin, and β-carotene had the most favorable effects on lung cancer prevention. Higher consumption of antioxidants from food sources has a protective effect against lung cancer, while no effects were shown in the supplemental group. It is recommended to consume a combination of various antioxidants due to the potential benefits from the interaction, while more research should be performed to investigate the underlying mechanisms of antioxidant synergic effects on lung cancer risk reduction.

Regulation of wheat bran feruloyl oligosaccharides in the intestinal antioxidative capacity of rats associated with the p38/JNK-Nrf2 signaling pathway and gut microbiota

BACKGROUND

Feruloyl oligosaccharides (FOs), the ferulic acid ester of oligosaccharides, may possess the physiological functions of both ferulic acid and oligosaccharides, including antioxidative activity and gut microbiota modulation capacity. The present study aimed to investigate whether FOs could regulate the intestinal antioxidative capacity of rats by modulating the MAPKs/Nrf2 signaling pathway and gut microbiota. Thirty Wistar rats were randomly divided into five groups. Rats received a standard diet and were gavaged once daily with 0.85% normal saline, 100 mg kg^-1 body weight vitamin C or FOs solution at doses of 20, 40 and 80 mg kg^-1 body weight for 21 days.

RESULTS

FOs strengthened the antioxidative capacity of the jejunum, as indicated by increased in contents of catalase, superoxide dismutase and glutathione peroxidase, as well as glutathione. Moreover, FOs administration upregulated the mRNA expression level of antioxidant-related genes (glutamate-cysteine ligase catalytic subunit, glutamate-cysteine ligase modifier subunit and heme oxygenase-1) in the jejunum. Increases in phosphorylation levels of Nrf2, p38 and JNK were also observed. Administration with 40 mg kg^-1 FOs altered the structure and composition of the cecal microbiota, which was indicated by the increased the relative abundances of Actinobacteria, Proteobacteria and Acidobacteriota, and the decreased the relative abundances of Firmicutes, Lachnospiraceae_NK4A136_group and Blautia. Furthermore, Spearman correlation analysis revealed that the altered cecal microbiota closely correlated with jejunal antioxidative capacity of rats.

CONCLUSION

FOs could be used as an antioxidant for gut heath improvement through modulating the p38/JNK-Nrf2 signaling pathway and gut microbiota. © 2022 Society of Chemical Industry.

Circulating vitamin C and digestive system cancers: Mendelian randomization study

BACKGROUND & AIMS

Vitamin C is an antioxidant with a potential role in the prevention of digestive system cancers, but there is yet no consensus whether vitamin C has a causal role in these cancers. The aim of this study was to utilize Mendelian randomization to decipher the potential causal associations of vitamin C with risk of digestive system cancers.

METHODS

Ten genetic variants previously found to be significantly associated with circulating vitamin C were used as instrumental variables. Effect size estimates for the genetic associations of the vitamin C-associated genetic variants with six major malignancies of digestive system were obtained from the FinnGen (N = 309 154) and UK Biobank (N = 367 542) studies. Results from the two studies were combined using meta-analysis.

RESULTS

Genetically predicted higher circulating vitamin C showed a suggestive association with lower risk of small intestine and colorectal cancer after accounting for multiple testing. The odds ratio per 1 standard deviation increment in circulating vitamin C was 0.55 (95% confidence interval 0.32-0.94; P = 0.029) for small intestine cancer and 0.84 (95% confidence interval 0.73-0.96; P = 0.013) for colorectal cancer. There was a suggestive association between genetically predicted higher circulating vitamin C with lower risk of liver cancer in FinnGen but no association in the meta-analysis (odds ratio 0.69; 95% CI 0.36-1.32; P = 0.265). Genetically predicted circulating vitamin C was not associated with cancers of the esophagus, stomach, or pancreas.

CONCLUSION

This Mendelian randomization study indicates that vitamin C might play a role in the prevention of small intestine and colorectal cancer.

Association of Visit-to-Visit Variability in Fasting Plasma Glucose with Digestive Cancer Risk

BACKGROUND AND AIMS

The aim of this study is to investigate the association between visit-to-visit variability in fasting plasma glucose (FPG) and the risk of digestive cancers among individuals with and without diabetes.

METHODS

Using data from Kailuan cohort, a prospective population-based study, individuals who had at least two measurements of FPG between 2006 and 2012 without prior cancer were included in this study. Four indexes of variability were used, including standard deviation (SD), coefficient of variation (CV), variability independent of the mean (VIM), and average successive variability (ARV). Cox regression was used to evaluate the relationship between the quartiles of FPG variability and digestive cancers.

RESULTS

A total of 98,161 individuals were studied. Over a mean follow-up of 9.32 ± 0.81 years, 1103 individuals developed incident digestive cancer (1.21 per 1000 person-years). Compared to the individuals in the lowest quartile, those in the highest quartile of FPG variability by SD had 38.7% higher risk of developing overall digestive cancers after adjusting for the significant confounders (hazard ratio, 1.387; 95% confidence interval, 1.160-1.659; P = 0.0003). Higher FPG variability was associated with significantly higher risks of colorectal cancer (fully adjusted HR 1.432, 95% CI [1.073-1.912], P = 0.015) and pancreatic cancer (fully adjusted HR 2.105, 95% CI [1.024-4.329], P = 0.043), but not liver cancer (fully adjusted HR 1.427, 95% CI [0.973-2.092], P = 0.069) or esophageal and gastric cancer (fully adjusted HR 1.139, 95% CI [0.776-1.670], P = 0.506). Subgroup analyses showed that individuals who were younger (<65 years), male, and those without diabetes experienced a predominantly higher risk of developing digestive cancers. Similar results were observed when using CV, VIM, and ARV.

CONCLUSIONS

FPG variability was significantly associated with increasing risk of digestive cancers, especially for pancreatic and colorectal cancer. Our study suggested a potential role of FPG variability in risk stratification of digestive cancers. Approaches that reduce FPG variability may lower the risks of incident digestive cancers among the general population. This trial is registered with ChiCTR-TNRC-11001489.

Effects of Coenzyme Q10 Supplementation on Biomarkers of Oxidative Stress in Adults: A GRADE-Assessed Systematic Review and Updated Meta-Analysis of Randomized Controlled Trials

Evidence shows that exogenous CoQ10 supplementation may potentially attenuate oxidative stress status. However, its effective dose and evidence certainty require further evaluation in the general population via more updated randomized controlled trials (RCTs). Databases (PubMed, Embase and Cochrane Library) were searched up to 30 March 2022. Evidence certainty was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Thirty-four RCTs containing 2012 participants were included in this review. Pooled effects of significant increase in total antioxidant capacity (TAC) (standardized mean difference: 1.83, 95%CI: [1.07, 2.59], p < 0.001) and significant reduction in malondialdehyde (MDA) concentrations (−0.77, [−1.06, −0.47], p < 0.001) were shown after CoQ10 supplementation compared to placebo. However, we could not determine that there was a significant increase in circulating superoxide dismutase (SOD) levels yet (0.47, [0.00, 0.94], p = 0.05). Subgroup analyses implied that CoQ10 supplementation was more beneficial to people with coronary artery disease or type 2 diabetes. Additionally, taking 100−150 mg/day CoQ10 supplement had better benefits for the levels of TAC, MDA and SOD (all p < 0.01). These results to a statistically significant extent lent support to the efficacy and optimal dose of CoQ10 supplementation on attenuating oxidative stress status in adults.

Circulating vitamin C concentration and risk of cancers: a Mendelian randomization study

BACKGROUND

Circulating vitamin C concentrations have been associated with several cancers in observational studies, but little is known about the causal direction of the associations. This study aims to explore the potential causal relationship between circulating vitamin C and risk of five most common cancers in Europe.

METHODS

We used summary-level data for genetic variants associated with plasma vitamin C in a large vitamin C genome-wide association study (GWAS) meta-analysis on 52,018 Europeans, and the corresponding associations with lung, breast, prostate, colon, and rectal cancer from GWAS consortia including up to 870,984 participants of European ancestry. We performed two-sample, bi-directional Mendelian randomization (MR) analyses using inverse-variance-weighted method as the primary approach, while using 6 additional methods (e.g., MR-Egger, weighted median-based, and mode-based methods) as sensitivity analysis to detect and adjust for pleiotropy. We also conducted a meta-analysis of prospective cohort studies and randomized controlled trials to examine the association of vitamin C intakes with cancer outcomes.

RESULTS

The MR analysis showed no evidence of a causal association of circulating vitamin C concentration with any examined cancer. Although the odds ratio (OR) per one standard deviation increase in genetically predicted circulating vitamin C concentration was 1.34 (95% confidence interval 1.14 to 1.57) for breast cancer in the UK Biobank, this association could not be replicated in the Breast Cancer Association Consortium with an OR of 1.05 (0.94 to 1.17). Smoking initiation, as a positive control for our reverse MR analysis, showed a negative association with circulating vitamin C concentration. However, there was no strong evidence of a causal association of any examined cancer with circulating vitamin C. Sensitivity analysis using 6 different analytical approaches yielded similar results. Moreover, our MR results were consistent with the null findings from the meta-analysis exploring prospective associations of dietary or supplemental vitamin C intakes with cancer risk, except that higher dietary vitamin C intake, but not vitamin C supplement, was associated with a lower risk of lung cancer (risk ratio: 0.84, 95% confidence interval 0.71 to 0.99).

CONCLUSIONS

These findings provide no evidence to support that physiological-level circulating vitamin C has a large effect on risk of the five most common cancers in European populations, but we cannot rule out very small effect sizes.

Risk of Colorectal Cancer in a Brazilian Population is Differentially Associated with the Intake of Processed Meat and Vitamin E

The incidence and mortality rates of colorectal cancer (CRC) in Northeast Brazil are increasing. To study the association between CRC and diet, data were obtained from 64 patients with CRC and 123 sex- and age-matched controls. The dietary details were recorded using a validated food frequency questionnaire. Nutrient intake was calculated using Dietsys software (National Cancer Institute, Maryland, USA). In a binary logistic regression model of dietary components (model 1), the chance of CRC increased by 0.2% (odds ratio [OR] = 1.002; 95% confidence interval [CI]: 1.000-1.004) for each gram of processed meat intake per week (p < 0.010). Consumption of eggs decreased the chance by 0.1% per gram (OR = 0.999; 95% CI: 0.998-1.000; p < 0.050). The use of oil (including olive oil) for served food decreased the chance by 1.8% (OR = 0.982; 95% CI: 0.970-0.992) for each time consumed (p < 0.010). In a model of nutritional factors (model 2), intake of vitamin E decreased the chance by 16.8% (OR = 0.832; 95% CI: 0.725-0.940) for each milligram intake per week (p < 0.010). In model 1 and 2 smoking increased the chance of CRC by 10.294 (95%CI: 4.240-27.670) and 2.496 (95% CI: 1.425-3.566) times (p < 0.010; p < 0.010), respectively.

Feed Composition Differences Resulting from Organic and Conventional Farming Practices Affect Physiological Parameters in Wistar Rats-Results from a Factorial, Two-Generation Dietary Intervention Trial

Recent human cohort studies reported positive associations between organic food consumption and a lower incidence of obesity, cancer, and several other diseases. However, there are very few animal and human dietary intervention studies that provide supporting evidence or a mechanistic understanding of these associations. Here we report results from a two-generation, dietary intervention study with male Wistar rats to identify the effects of feeds made from organic and conventional crops on growth, hormonal, and immune system parameters that are known to affect the risk of a number of chronic, non-communicable diseases in animals and humans. A 2 × 2 factorial design was used to separate the effects of contrasting crop protection methods (use or non-use of synthetic chemical pesticides) and fertilizers (mineral nitrogen, phosphorus and potassium (NPK) fertilizers vs. manure use) applied in conventional and organic crop production. Conventional, pesticide-based crop protection resulted in significantly lower fiber, polyphenol, flavonoid, and lutein, but higher lipid, aldicarb, and diquat concentrations in animal feeds. Conventional, mineral NPK-based fertilization resulted in significantly lower polyphenol, but higher cadmium and protein concentrations in feeds. Feed composition differences resulting from the use of pesticides and/or mineral NPK-fertilizer had a significant effect on feed intake, weight gain, plasma hormone, and immunoglobulin concentrations, and lymphocyte proliferation in both generations of rats and in the second generation also on the body weight at weaning. Results suggest that relatively small changes in dietary intakes of (a) protein, lipids, and fiber, (b) toxic and/or endocrine-disrupting pesticides and metals, and (c) polyphenols and other antioxidants (resulting from pesticide and/or mineral NPK-fertilizer use) had complex and often interactive effects on endocrine, immune systems and growth parameters in rats. However, the physiological responses to contrasting feed composition/intake profiles differed substantially between the first and second generations of rats. This may indicate epigenetic programming and/or the generation of "adaptive" phenotypes and should be investigated further.

Lonicera caerulea L. Polyphenols Alleviate Oxidative Stress-Induced Intestinal Environment Imbalance and Lipopolysaccharide-Induced Liver Injury in HFD-Fed Rats by Regulating the Nrf2/HO-1/NQO1 and MAPK Pathways

SCOPE

This study investigates the modulatory effects of Lonicera caerulea L. polyphenols (LCPs) on the intestinal environment and lipopolysaccharide (LPS)-induced liver injury via the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (HO-1)/NQO1 and mitogen-activated protein kinase (MAPK) pathways in a rat model of oxidative stress damage (OSD).

METHODS AND RESULTS

To examine the prebiotic properties of LCP, a model of high-fat-diet-induced OSD is established using Sprague Dawley rats. In the colon, treatment with LCP for 8 weeks ameliorates enhanced intestinal permeability (glucagon-like peptide-2 content and occludin protein increase, whereas claudin-2 protein decreases), intestinal inflammation (levels of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nuclear factor kappa-B p65 (NF-κB p65), decrease), and intestinal OSD (through regulation of the Nrf2/HO-1/NQO1 pathway). Moreover, LCP alleviates LPS-induced liver injury by suppressing the nuclear translocation of NF-κB p65 and activation of the MAPK signaling pathway. Additionally, Bacilli, Lactobacillales, Lactobacillaceae, Lactobacillus, Akkermansia, Actinobacteria, Proteobacteria, Rothia, and Blautia are found to be the key intestinal microbial taxa related to intestinal OSD and LPS-induced liver injury in rats.

CONCLUSION

LCP treatment potentially modulates the intestinal environment and alleviates liver injury by suppressing oxidative-stress-related pathways and altering the composition of the intestinal microbiota.

Vitamin E and cancer prevention: Studies with different forms of tocopherols and tocotrienols

α-Tocopherol (α-T) is the major form of vitamin E (VE) in animals and has the highest activity in carrying out the essential antioxidant functions of VE. Because of the involvement of oxidative stress in carcinogenesis, the cancer prevention activity of α-T has been studied extensively. Lower VE intake or nutritional status has been shown to be associated with increased cancer risk, and supplementation of α-T to populations with VE insufficiency has shown beneficial effects in lowering the cancer risk in some intervention studies. However, several large intervention studies with α-T conducted in North America have not demonstrated a cancer prevention effect. More recent studies have centered on the γ- and δ-forms of tocopherols and tocotrienols (T3). In comparison with α-T, these forms have much lower systemic bioavailability but have shown stronger cancer-preventive activities in many studies in animal models and cell lines. γ-T3 and δ-T3 generally have even higher activities than γ-T and δ-T. In this article, we review recent results from human and laboratory studies on the cancer-preventive activities of different forms of tocopherols and tocotrienols, at nutritional and pharmacological levels. We aim to elucidate the possible mechanisms of the preventive actions and discuss the possible application of the available information for human cancer prevention by different VE forms.

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.