Diet and prostate cancer: a case-control study

The association between zinc and prostate cancer development: A systematic review and meta-analysis

BACKGROUND

Prostate cancer is affecting males globally, with several complications. Zinc can play roles in cancers. We aimed to clarify the association between zinc levels or intake with prostate cancer development.

METHODS

We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science until May 1, 2023. We included case-controls and cross-sectionals that measured zinc level and/or intake in patients with prostate cancer or cohorts that evaluated the association between zinc and prostate cancer development. Studies that did not have a healthy control group were excluded. Joanna Briggs Institute was used for quality assessment. Publication bias was evaluated using Egger's and Begg's tests and funnel plot.

RESULTS

Overall, 52 studies (n = 44 case controls, n = 4 cohorts, and n = 4 cross sectionals) with a total number of 163909 participants were included. Serum (standardized mean difference (SMD): -1.11; 95% confidence interval (CI): -1.67, -0.56), hair (SMD: -1.31; 95% CI: -2.19, -0.44), and prostatic fluid or tissue zinc levels (SMD: -3.70; 95% CI: -4.90, -2.49) were significantly lower in prostate cancer patients. There were no significant differences in nail zinc level and zinc intake between those with prostate cancer and healthy controls. There was no publication bias except for serum and hair zinc levels based on Begg's and Egger's tests, respectively. The mean risk of bias scores were 4.61 in case-controls, eight in cohorts, and seven in cross-sectionals.

CONCLUSIONS

Overall, high zinc levels might have a protective role in prostate cancer, which can be used as a therapeutic or preventive intervention. Future large-scale studies are needed to confirm the association.

Association of saturated fatty acids with cancer risk: a systematic review and meta-analysis

OBJECTIVE

Extensive research has explored the link between saturated fatty acids (SFAs) and cardiovascular diseases, alongside other biological dysfunctions. Yet, their association with cancer risk remains a topic of debate among scholars. The present study aimed to elucidate this association through a robust meta-analysis.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were searched systematically to identify relevant studies published until December 2023. The Newcastle-Ottawa Scale was used as the primary metric for evaluating the quality of the included studies. Further, fixed- or random-effects models were adopted to determine the ORs and the associated confidence intervals using the Stata15.1 software. The subsequent subgroup analysis revealed the source of detection and the cancer types, accompanied by sensitivity analyses and publication bias evaluations.

RESULTS

The meta-analysis incorporated 55 studies, comprising 38 case-control studies and 17 cohort studies. It revealed a significant positive correlation between elevated levels of total SFAs and the cancer risk (OR of 1.294; 95% CI: 1.182-1.416; P-value less than 0.001). Moreover, elevated levels of C14:0, C16:0, and C18:0 were implicated in the augmentation of the risk of cancer. However, no statistically significant correlation of the risk of cancer was observed with the elevated levels of C4:0, C6:0, C8:0, C10:0, C12:0, C15:0, C17:0, C20:0, C22:0, and C24:0. Subgroup analysis showed a significant relationship between excessive dietary SFA intake, elevated blood SFA levels, and heightened cancer risk. Increased total SFA levels correlated with higher risks of breast, prostate, and colorectal cancers, but not with lung, pancreatic, ovarian, or stomach cancers.

CONCLUSION

High total SFA levels were correlated with an increased cancer risk, particularly affecting breast, prostate, and colorectal cancers. Higher levels of specific SFA subtypes (C14:0, C16:0, and C18:0) are also linked to an increased cancer risk. The findings of the present study would assist in providing dietary recommendations for cancer prevention, thereby contributing to the development of potential strategies for clinical trials in which diet-related interventions would be used in combination with immunotherapy to alter the levels of SFAs in patients and thereby improve the outcomes in cancer patients. Nonetheless, further high-quality studies are warranted to confirm these associations.

Effect of dietary antioxidants on the risk of prostate cancer. Systematic review and network meta-analysis

OBJECTIVE

the purpose of this study was to assess the impact of 14 treatments including a total of 10 dietary antioxidants on the risk of prostate cancer.

MATERIAL AND METHODS

we searched PubMed, Embase, the Cochrane Library, and the Web of Science for only randomized controlled trials (RCTs) to investigate the effect of these 10 antioxidants on the risk of getting prostate cancer. Using the Cochrane Risk of Bias Assessment Tool, the methodological quality of the included studies was evaluated.

DATA EXTRACTION

studies were appraised by two investigators and data were extracted. Using a surface under cumulative ranking (SUCRA) probability, a Bayesian network meta-analysis was undertaken to evaluate the relative ranking of agents.

RESULTS

from the earliest accessible date through August 2022, RCTs were gathered. A total of 14 randomized controlled trials were included with a total sample size of 73,365 males. The results of the network meta-analysis showed that green tea catechins (GTCs) significantly reduced the risk of prostate cancer (SUCRA, 88.6 %) followed by vitamin D (SUCRA, 55.1 %), vitamin B6 (54.1 %), and folic acid was the lowest (22.0 %).

CONCLUSION

based on the Ranking Plot of the Network, we can state that GTCs might have an impact on the prevention of prostate cancer compared to other dietary antioxidants, but we still need quality literature to further prove it.

Interactions of SNPs in Folate Metabolism Related Genes on Prostate Cancer Aggressiveness in European Americans and African Americans

Background: Studies showed that folate and related single nucleotide polymorphisms (SNPs) could predict prostate cancer (PCa) risk. However, little is known about the interactions of folate-related SNPs associated with PCa aggressiveness. The study’s objective is to evaluate SNP–SNP interactions among the DHFR 19-bp polymorphism and 10 SNPs in folate metabolism and the one-carbon metabolism pathway associated with PCa aggressiveness. Methods: We evaluated 1294 PCa patients, including 690 European Americans (EAs) and 604 African Americans (AAs). Both individual SNP effects and pairwise SNP–SNP interactions were analyzed. Results: None of the 11 individual polymorphisms were significant for EAs and AAs. Three SNP–SNP interaction pairs can predict PCa aggressiveness with a medium to large effect size. For the EA PCa patients, the interaction between rs1801133 (MTHFR) and rs2236225 (MTHFD1), and rs1801131 (MTHFR) and rs7587117 (SLC4A5) were significantly associated with aggressive PCa. For the AA PCa patients, the interaction of DHFR-19bp polymorphism and rs4652 (LGALS3) was significantly associated with aggressive PCa. Conclusions: These SNP–SNP interactions in the folate metabolism-related genes have a larger impact than SNP individual effects on tumor aggressiveness for EA and AA PCa patients. These findings can provide valuable information for potential biological mechanisms of PCa aggressiveness.

Vitamin E Intake and Risk of Prostate Cancer: A Meta-Analysis

Vitamin E is a group of antioxidative tocopherols and tocotrienols that play a potential role in chemoprevention. Studies investigating the association between vitamin E and prostate cancer risk have been conflicting. We identified observational and interventional studies examining the association between vitamin E intake and prostate cancer risk from PubMed, EMBASE and the Cochrane Library. A random-effects model was used to perform a meta-analysis and estimate relative risks (RRs) and the corresponding 95% confidence intervals (CIs) of prostate cancer risk according to vitamin E intake. Subgroup analyses were conducted by study design, sample size, study population characteristics, geographical region, and dose of vitamin E intake. The association between dietary (RR = 0.97; 95% CI = 0.92-1.02) and supplemental (RR = 0.99; 95% CI = 0.94-1.04) vitamin E intake on prostate cancer risk was non-significant. In subgroup analyses, supplemental vitamin E was significantly associated with reduced prostate cancer risk in studies in Europe (RR = 0.81, 95% CI = 0.69-0.97). Overall, this meta-analysis demonstrates little evidence for a beneficial effect of vitamin E intake on prostate cancer risk but suggests that there may be some conditions in which supplements could confer a protective effect on prostate cancer risk.

Circulating phosphorus concentration and risk of prostate cancer: a Mendelian randomization study

BACKGROUND

Recent observational studies have suggested that circulating phosphorus concentrations are positively associated with the risk of prostate cancer. However, little is known about the causal direction of the association.

OBJECTIVES

To explore the potential causal relation between circulating phosphorus and risk of prostate cancer, we conducted a Mendelian randomization (MR) study.

METHODS

Summary statistics of prostate cancer were obtained from a meta-analysis of genome-wide association studies (GWASs) consisting of 79,148 cases and 61,106 controls. Single-nucleotide polymorphisms (SNPs) associated with serum phosphorus concentration were selected from a GWAS of 291,408 individuals from the UK Biobank. MR analysis was performed using the inverse variance weighted (IVW) method, supplemented with simple median method, weighted median method, maximum likelihood-based method, MR-Egger regression, and the MR pleiotropy residual sum and outlier test. We also performed a meta-analysis of observational studies to assess the associations of dietary phosphorus intake and serum phosphorus concentration with risk of prostate cancer.

RESULTS

In the MR analysis, a total of 125 independent SNPs associated with serum phosphorus concentrations were used as instrumental variables. Genetically predicted serum phosphorus concentrations were associated with a 19% increased risk of prostate cancer (95% CI: 9%, 31%) per 1-SD increment of serum phosphorus by IVW (P = 1.82 × 10-4). Sensitivity analyses using alternative MR methods produced similar positive associations, and no evidence of pleiotropy was detected by MR-Egger regression (P = 0.422). For meta-analysis, 8 studies for dietary phosphorus intake and 4 for serum phosphorus concentrations were included involving a total of 669,080 participants. Consistently, high dietary phosphorus intake and serum phosphorus concentrations were associated with an 8% (95% CI: 4%, 12%) and 7% (95% CI: 1%, 14%) increase in prostate cancer risk, respectively.

CONCLUSIONS

Our study suggested a potential causal relation between circulating phosphorus and risk of prostate cancer. Further studies are warranted to elucidate the underlying mechanism of phosphorus in the development of prostate cancer.

Rise in serum folate after androgen deprivation associated with worse prostate cancer-specific survival

INTRODUCTION

High folate has an association with advanced prostate cancer and levels of testosterone. Herein, we perform a translational study to investigate the inverse response of serum folate in prostate cancer patients initiating androgen deprivation therapy (ADT) and a mirrored animal model.

METHODS

A retrospective study was performed using the South Texas Veterans Healthcare System to identify patients with prostate cancer on ADT. We documented testosterone and folate levels before and after ADT initiation (defined by a reduction in testosterone by 50 ng/ml) as compared to those already on ADT (maintenance). Our primary outcome was overall mortality with secondary outcome of prostate cancer-specific mortality. In parallel, we tested castration of C57BL/6J mice on folate-defined diet to determine if folate levels change with response to androgen deprivation. Students' t test on continuous variables and Chi-squared test on dichotomous variables was performed along with Kaplan-Meier for time to event analysis.

RESULTS

We identified 56 men with prostate cancer undergoing androgen deprivation in which folate levels had been determined. 15 out of 16 (94%) men initiating ADT had increases in their folate, which is substantially more than 67% in maintenance group (P = 0.04). We identified more rapid time to death from prostate cancer if folate levels increased to levels >200 ng/ml above their baseline (P = 0.03). Mice models demonstrated a significant rise in serum red blood cell folate after mice were castrated (P = 0.03) by an average of 1.5x over pre-castrated baseline level. By contrast, sham-castrated mice showed no increase in serum folate levels over baseline.

CONCLUSION

Our study suggests that men with substantial rises in folate after initiating ADT may be associated with worse prostate cancer-specific and overall survival. Our translational experiments in mice confirmed correlation between rising in folate levels post-castration. Given this study, further investigation is warranted on the role of dietary folate consumption during initiation of ADT and progression to castrate-resistant prostate cancer.

Beta-Tocotrienol Exhibits More Cytotoxic Effects than Gamma-Tocotrienol on Breast Cancer Cells by Promoting Apoptosis via a P53-Independent PI3-Kinase Dependent Pathway

Studies on tocotrienols have progressively revealed the benefits of these vitamin E isoforms on human health. Beta-tocotrienol (beta-T3) is known to be less available in nature compared to other vitamin E members, which may explain the restricted number of studies on beta-T3. In the present study, we aim to investigate the anti-proliferative effects and the pro-apoptotic mechanisms of beta-T3 on two human breast adenocarcinoma cell lines MDA-MB-231 and MCF7. To assess cell viability, both cell lines were incubated for 24 and 48 h, with different concentrations of beta-T3 and gamma-T3, the latter being a widely studied vitamin E isoform with potent anti-cancerous properties. Cell cycle progression and apoptosis induction upon treatment with various concentrations of the beta-T3 isoform were assessed. The effect of beta-T3 on the expression level of several apoptosis-related proteins p53, cytochrome C, cleaved-PARP-1, Bax, Bcl-2, and caspase-3, in addition to key cell survival proteins p-PI3K and p-GSK-3 α/β was determined using western blot analysis. Beta-tocotrienol exhibited a significantly more potent anti-proliferative effect than gamma-tocotrienol on both cell lines regardless of their hormonal receptor status. Beta-T3 induced a mild G1 arrest on both cell lines, and triggered a mitochondrial stress-mediated apoptotic response in MDA-MB-231 cells. Mechanistically, beta-T3′s anti-neoplastic activity involved the downregulation of phosphorylated PI3K and GSK-3 cell survival proteins. These findings suggest that vitamin E beta-T3 should be considered as a promising anti-cancer agent, more effective than gamma-T3 for treating human breast cancer and deserves to be further studied to investigate its effects in vitro and on other cancer types.

Oxidative damage in patients with benign prostatic hyperplasia and prostate cancer co-exposed to phthalates and to trace elements

Evidence indicates that prostates exposed to environmental endocrine disruptors and trace metals will cause adverse health outcomes. We assessed the association between urinary phthalate metabolites and serum trace metal levels, and oxidative damage in benign prostatic hyperplasia (BPH) patients, prostate cancer (PCa) patients, and healthy controls. Levels of cadmium (Cd), nickel (Ni), and copper (Cu) were significantly higher in BPH patients than in controls, and mercury (Hg) was highest in PCa patients. An Hg level >1 μg/L posed a significant risk (OR: 42.86, 95% CI: 1.092-1684) for PCa, but a zinc (Zn) level >1 μg/L was marginally negative (OR: 0.979, 95% CI: 0.957-1.002). We also found strong associations between PCa and mono-isononyl phthalate (MiNP), and between BPH and mono-isodecyl phthalate (MiDP), malonyldialdehyde (MDA) were significantly higher in PCa and BPH patients than in controls; 8‑hydroxydeoxyguanosine (8‑OH‑dG) and DNA strand breakage were highest in BPH patients and lowest in controls. When the prostate was simultaneously co-exposed to phthalates and trace metals, phthalates had a less significant effect on PCa and BPH. Thus, we hypothesize that, for patients with prostate disease, exposure to trace metals is more significant than is exposure to phthalates.

Carbohydrate intake and the risk of prostate cancer

BACKGROUND

Prostate cancer (PCa) is one of the leading cause cancer among men worldwide. Many epidemiologic studies have reported an association between carbohydrate intake and PCa. However, the evidence from epidemiologic studies is inconsistent. We conducted a comprehensive meta-analysis to explore the associations between carbohydrate intake and PCa risk and to investigate potential dose-response relationships.

METHODS

We searched PubMed and EMBASE for studies published from 1980 to 2018. 21 studies were included with 98,739 participants and 11,573 cases. Multivariate-adjusted odds ratios (ORs) were pooled using random-effect models. Potential dose-response relationships were evaluated for PCa risk.

RESULTS

We did not detect an association about higher carbohydrate intake and PCa risk (OR:1.11, 95% confidence interval [CI]: 0.98-1. 26, I² = 62.7%), nor association was detected about higher carbohydrate intake with advanced PCa risk (OR:0.95, 95% CI: 0.78-1.16, I² = 14.1%) or non-advanced Pca risk (OR:1.01, 95% CI: 0.79-1.29, I² = 64.4%). There was not a significant dose-response association observed for carbohydrate intake with PCa risk and advanced PCa risk.

CONCLUSIONS

Our meta-analysis shows no association between carbohydrate intake and prostate cancer risk. Nor is association detected about carbohydrate intake with advanced or non-advanced Pca risk. More studies are needed for a further dose-response meta-analysis.

Non-Occupational Risk Factors for Bladder Cancer a Case-Control Study

Aims

The aim of this study was to determine non-occupational risk factors for bladder cancer in Serbia.

Methods and design

A hospital-based, case-control study included 130 newly diagnosed bladder cancer patients and the same number of individually matched controls with respect to sex, age (± 2 years) and type of residence (rural or urban), from the Clinical Center of Serbia in Belgrade and from the Clinical Center in Kragujevac in central Serbia. The study took place from June 1997 to March 1999.

Results

According to multivariate logistic regression analysis, there was an association between: frequency of daily urination (OR = 0.18; 95% CI = 0.08-0.39); consumption of liver (OR = 13.81; 95% CI = 2.49-76.69), canned meat (OR = 8.38; 95% CI = 1.74-40.36), fruit juices (OR = 0.08; 95% CI = 0.01-0.56); the highest fertile of pork (OR = 4.55; 95% CI = 1.30-15.93), cabbage (OR = 0.25; 95% CI = 0.06-1.01) and vinegar (OR = 4.41; 95% CI = 1.18-16.50) intake and risk for bladder cancer.

Conclusions

Consumption of liver, canned meat, pork (h vs I tertile) and vinegar (m vs I tertile) was indicated as a risk factor for bladder cancer, whereas frequent daily urination, consumption of fruit juices and cabbage (h vs I fertile) were indicated as protective factors.

Zinc Intake and Risk of Prostate Cancer: Case-Control Study and Meta-Analysis

Zinc is an essential dietary element that has been implicated in the pathogenesis of prostate cancer, a cancer that disproportionately affects men of African descent. Studies assessing the association of zinc intake and prostate cancer have yielded inconsistent results. Furthermore, very little is known about the relationship between zinc intake and prostate cancer among African Americans. We examined the association between self-reported zinc intake and prostate cancer in a hospital-based case-control study of African Americans. We then compared our results with previous studies by performing a meta-analysis to summarize the evidence regarding the association between zinc and prostate cancer. Newly diagnosed African American men with histologically confirmed prostate cancer (n = 127) and controls (n = 81) were recruited from an urban academic urology clinic in Washington, DC. Controls had higher zinc intake, with a mean of 14 mg/day versus 11 mg/day for cases. We observed a non-significant, non-linear increase in prostate cancer when comparing tertiles of zinc intake (OR <6.5 vs 6.5-12.5mg/day 1.8, 95% CI: 0.6,5.6; OR <6.5 vs >12.5mg/day 1.3, 95% CI: 0.2,6.5). The pooled estimate from 17 studies (including 3 cohorts, 2 nested case-control, 11 case-control studies, and 1 randomized clinical trial, with a total of 111,199 participants and 11,689 cases of prostate cancer) was 1.07hi vs lo 95% CI: 0.98-1.16. Using a dose-response meta-analysis, we observed a non-linear trend in the relationship between zinc intake and prostate cancer (p for nonlinearity = 0.0022). This is the first study to examine the relationship between zinc intake in black men and risk of prostate cancer and systematically evaluate available epidemiologic evidence about the magnitude of the relationship between zinc intake and prostate cancer. Despite of the lower intake of zinc by prostate cancer patients, our meta-analysis indicated that there is no evidence for an association between zinc intake and prostate cancer.

Diet, Lifestyles, Family History, and Prostate Cancer Incidence in an East Algerian Patient Group

Prostate cancer (PC) is the fourth most common cancer in men and the sixth leading cause of death in Algeria. To examine the relationship between lifestyle factors, including diet, and family history and PC risk, a case-control study was performed in an eastern Algerian population, comprising 90 patients with histologically confirmed PC and 190 controls. Data collection was carried out through a structured questionnaire and statistical analysis was performed to evaluate the different variables. The data showed that consumption of lamb and beef meat and high intake of animal fat and dairy products increased PC risk. Seven to thirteen vegetables servings per week and fourteen or more servings decreased PC risk by 62% and 96%, respectively. Seven to fourteen fruit servings per week decrease PC risk by 98%. Green tea consumption reduced the risk of PC but the results were statistically borderline. Increased risk was observed for individuals with family history of PC in first and in second degree. A positive strong association was also found for alcohol and smoking intake and a dose-response relationship existed for quantity and history of smoking. This study suggests that dietary habits, lifestyle factors, and family history have influence on the development of PC in Algerian population.

The role of micronutrients in the risk of urinary tract cancer

Prostate, bladder and kidney cancers remain the most common urological malignancies worldwide, and the prevention and treatment of these diseases pose a challenge to clinicians. In recent decades, many studies have been conducted to assess the association between supplementation with selected vitamins and elements and urinary tract tumour initiation and development. Here, we review the relationship between vitamins A, B, D, and E, in addition to calcium, selenium, and zinc, and the risk of developing prostate, kidney and bladder cancer. A relatively consistent body of evidence suggests that large daily doses of calcium (> 2,000 mg/day) increase the risk of prostate cancer. Similarly, supplementation with 400 IU/day of vitamin E carries a significant risk of prostate cancer. However, there have been many conflicting results regarding the effect of these nutrients on kidney and bladder neoplasms. Moreover, the role of other compounds in urinary tract carcinogenesis needs further clarification.

Selenium and vitamin E for prostate cancer--justifications for the SELECT study

There are several studies that relate oxidative damage as possible mechanism for many cancers. Many studies have also shown that anti-oxidants like selenium and vitamin E decrease the risk for prostate cancer. The main objective of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) study was to look for the benefits of selenium and vitamin E supplementation on prostate cancer. The study had a large sample size, stringent experimental conditions, very long duration, standardized laboratories for biochemical analyses and other factors that contribute to high external validity. The SELECT study failed to show any significant risk reduction for prostate cancers ascribable to selenium and vitamin E supplementations. Because of these conflicting results, many researchers argue about the methods used, supplementations administered (selenium and vitamin E) and indicators used for assessing levels of supplementations. We reviewed many epidemiological studies, clinical trials, and pre-clinical studies. With corroborative evidences we justify that SELECT study has a sound methodology and rationale. In lieu of the contrary results of the select study, researchers should focus on the probable mechanisms for these contrary findings and continue their search for newer and effective agents for prevention of prostate cancer.

Dietary, supplement, and adipose tissue tocopherol levels in relation to prostate cancer aggressiveness among African and European Americans: The North Carolina-Louisiana Prostate Cancer Project (PCaP)

BACKGROUND

Controversies remain over the safety and efficacy of vitamin E (i.e., α-tocopherol) supplementation use for the prevention of prostate cancer (CaP); however, associations of different tocopherol forms and CaP aggressiveness have yet to be examined.

METHODS

This study examined whether food intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherol were associated with CaP aggressiveness among African-American (AA, n = 1,023) and European-American (EA, n = 1,079) men diagnosed with incident CaP. Dietary tocopherols were estimated from a food frequency questionnaire, supplement use from questionnaire/inventory, and biomarkers from abdominal adipose samples measured using high-performance liquid chromatography. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were estimated from logistic regression comparing high-aggressive CaP to low/intermediate aggressive CaP, adjusting for covariates.

RESULTS

Dietary intakes of α-and δ-tocopherol were related inversely to CaP aggressiveness among EAs [OR (95%CI), highest versus lowest quartile: α-tocopherol, 0.34 (0.17-0.69), P(trend)  = 0.006; δ-tocopherol, 0.45 (0.21-0.95) P(trend)  = 0.007]. Inverse associations between dietary and supplemental α-tocopherol and CaP aggressiveness were observed among AAs, though these did not reach statistical significance [OR (95%CI), highest versus lowest quartile: dietary α-tocopherol, 0.58 (0.28-1.19), P(trend)  = 0.20; supplemental α-tocopherol, 0.64 (0.31-1.21) P(trend)  = 0.15]. No significant association was observed between adipose tocopherol levels and CaP aggressiveness [OR (95%CI), highest versus lowest quartiles of α-tocopherol for EAs 1.43 (0.66-3.11) and AAs 0.66 (0.27-1.62)].

CONCLUSIONS

The inverse associations observed between dietary sources of tocopherols and CaP aggressiveness suggests a beneficial role of food sources of these tocopherols in CaP aggressiveness.

No association between fiber intake and prostate cancer risk: a meta-analysis of epidemiological studies

Background

The findings of epidemiologic studies on the association between fiber intake and prostate cancer risk remain conflicting. We aimed to examine this association by conducting a meta-analysis of epidemiological studies.

Methods

Relevant studies were identified by PubMed (1966 to March 2015) and Embase (1974 to March 2015) database search through March 2015. We included epidemiological studies that reported relative risks (RRs) or odds ratios (ORs) with 95 % confidence intervals (CIs) for the association between dietary fiber intake and prostate cancer risk. Random effects models were used to calculate the summary risk estimates.

Results

For the highest compared with the lowest dietary fiber intake, a significantly decreased risk with prostate cancer was observed in case-control studies (OR = 0.82; 95 % CI, 0.68–0.96), but not in cohort studies (RR = 0.94; 95 % CI, 0.77–1.11). The combined risk estimate of all studies was 0.89 (95 % CI, 0.77, 1.01). A significant heterogeneity was observed across studies (p = 0.005). There was no evidence of significant publication bias based on Begg’s funnel plot (p = 0.753) or Egger’s test (p = 0.946).

Conclusions

This meta-analysis suggests the absence of evidence for association between dietary fiber intake and prostate cancer risk.

Association between Dietary Vitamin C Intake and Risk of Prostate Cancer: A Meta-analysis Involving 103,658 Subjects

We attempted to systematically determine the association between dietary intake of vitamin C and risk of prostate cancer. PubMed and Embase were searched to obtain eligible studies published before February 2015. Cohort or case-control studies that reported the relative risk (RR)/odds ratio (OR) estimates with 95% confidence intervals (CIs) for the association between vitamin C intake and prostate cancer risk were included. Eighteen studies regarding dietary vitamin C intake were finally obtained, with a total of 103,658 subjects. The pooled RR of prostate cancer for the highest versus the lowest categories of dietary vitamin C intake was 0.89 (95%CI: 0.83-0.94; p = 0.000) with evidence of a moderate heterogeneity (I(2) = 39.4%, p = 0.045). Meta-regression analysis suggested that study design accounted for a major proportion of the heterogeneity. Stratifying the overall study according to study design yielded pooled RRs of 0.92 (95%CI: 0.86-0.99, p = 0.027) among cohort studies and 0.80 (95%CI: 0.71-0.89, p = 0.000) among case-control studies, with no heterogeneity in either subgroup. In the dose-response analysis, an inverse linear relationship between dietary vitamin C intake and prostate cancer risk was established, with a 150 mg/day dietary vitamin C intake conferred RRs of 0.91 (95%CI: 0.84-0.98, p = 0.018) in the overall studies, 0.95 (95%CI: 0.90-0.99, p = 0.039) in cohort studies, and 0.79 (95%CI: 0.69-0.91, p = 0.001) in case-control studies. In conclusion, intake of vitamin C from food was inversely associated with prostate cancer risk in this meta-analysis.

Dietary carbohydrate and prostate cancer risk: a meta-analysis

Carbohydrate intake has been inconsistently associated with risk of prostate cancer. We review and quantitatively summarize the evidence from observational studies in a meta-analysis. We searched the PubMed database for observational studies related to the association of carbohydrate intake and prostate cancer risk up to December 25, 2013. Summary relative risks (RRs) were estimated by the use of a random effects model. We included 13 case-control studies with 4,367 cases and 6,205 controls, and 5 cohort studies with 3,679 cases and 74,115 participants in this meta-analysis. The summary RR of prostate cancer for the highest vs. the lowest carbohydrate intake was 1.06 [95% confidence interval (CI): 0.93-1.20, I(2) = 46.8%] for all included studies. In the subgroup analyses stratified by study design, the summary RRs for the highest vs. the lowest carbohydrate intake were 1.04 (95% CI: 0.87-1.23) for case-control studies and 1.06 (95% CI: 0.88-1.28) for cohort studies. For the 5 studies that reported results for advanced prostate cancer, the summary RR was 0.92 (95% CI: 0.71-1.20). This meta-analysis of observational studies indicates that there is no association between carbohydrate intake and prostate cancer risk. Further studies are needed to confirm our findings.

Folate intake, serum folate levels, and prostate cancer risk: a meta-analysis of prospective studies

Background

Studies have reported inconsistent results concerning the existence of associations of folate intake and serum folate levels with prostate cancer risk. This study sought to summarise the evidence regarding these relationships using a dose–response meta-analysis approach.

Methods

In January 2014, we performed electronic searches of PubMed, Embase, and the Cochrane Library to identify studies examining the effect of folate on the incidence of prostate cancer. Only prospective studies that reported effect estimates with 95% confidence intervals (CIs) of the incidence of prostate cancer for more than 2 categories of folate were included.

Results

Overall, we included 10 prospective studies reporting data on 202,517 individuals. High dietary folate intake had little or no effect on prostate cancer risk (risk ratio [RR] = 1.02; 95% CI = 0.95–1.09; P = 0.598). The dose–response meta-analysis suggested that a 100 μg per day increase in dietary folate intake has no significant effect on the risk of prostate cancer (RR = 1.01; 95% CI = 0.99–1.02; P = 0.433). However, high serum folate levels were associated with an increased risk of prostate cancer (RR = 1.21; 95% CI = 1.05–1.39; P = 0.008). The dose–response meta-analysis indicated that a 5 nmol/L increment of serum folate levels was also associated with an increased risk of prostate cancer (RR = 1.04; 95% CI = 1.00–1.07; P = 0.042).

Conclusions

Our study indicated that dietary folate intake had little or no effect on prostate cancer risk. However, increased serum folate levels have potentially harmful effects on the risk of prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-1326) contains supplementary material, which is available to authorized users.

Folate intake and the risk of prostate cancer: a systematic review and meta-analysis

There is conflicting evidence regarding the role of folate on the risk of developing prostate cancer. We performed a systematic review and quantitative meta-analysis of folate blood levels and folate intake, and the risk of prostate cancer. Four electronic databases (Medline, PubMed, Embase and Current Contents Connect) were searched to 11 October 2013, with no language restrictions for observational studies that measured folate intake or blood levels and the risk of prostate cancer. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using a random effects model. The dietary folate meta-analysis comprising 11 studies with 15 336 cases and a total sample size of 146 782 found no statistically significant association with prostate cancer, with an OR of 0.97 (95% CI 0.89-1.06). The total folate meta-analysis comprising of 5 studies with 7114 cases and a total sample size of 93 781 also found no statistically significant association with prostate cancer, with an OR of 0.99 (95% CI 0.82-1.19). The blood folate meta-analysis comprising of seven studies with 6122 cases and a total sample size of 10 232 found an increased risk of prostate cancer with high blood folate levels, with an OR of 1.43 (95% CI 1.06-1.93). There was significant heterogeneity (I(2)=79.5%, P<0.01). Removal of an outlier study removed the heterogeneity (I(2)=0.0%, P=0.54) and the association remained significant with an OR of 1.14 (95% CI 1.02-1.28). Dietary and total folate intake do not appear to be significantly associated with the risk of prostate cancer. High blood folate levels are associated with an increased risk of prostate cancer. These conclusions are limited by the predominance of included studies originating from developed countries with mostly Caucasian populations. Further research in populations with a high prevalence of non-Caucasian backgrounds is needed.

Oxidative balance score and risk for incident prostate cancer in a prospective U.S. cohort study

PURPOSE

Oxidative stress is defined as an imbalance between pro-oxidants and antioxidants. Previous research found that a single comprehensive oxidative balance score (OBS) that includes individual pro- and anti-oxidant exposures may be associated with various conditions (including prostate cancer) in the absence of associations with the individual factors. We investigated an OBS-incident prostate cancer association among 43,325 men in the Cancer Prevention Study II Nutrition Cohort.

METHODS

From 1999-2007, 3386 incident cases were identified. Twenty different components, used in two ways (unweighted or weighted based on literature reviews), were incorporated into the OBS, and the resulting scores were then expressed as three types of variables (continuous, quartiles, or six equal intervals). Multivariable-adjusted rate ratios were calculated using Cox proportional hazards models.

RESULTS

We hypothesized that the OBS would be inversely associated with prostate cancer risk; however, the rate ratios (95% confidence intervals) comparing the highest with the lowest OBS categories ranged from 1.17 (1.04-1.32) to 1.39 (0.90-2.15) for all cases, 1.14 (0.87-1.50) to 1.59 (0.57-4.40) for aggressive disease (American Joint Committee on Cancer stage III/IV or Gleason score 8-10), and 0.91 (0.62-1.35) to 1.02 (1.02-1.04) for nonaggressive disease.

CONCLUSIONS

Our findings are not consistent with the hypothesis that oxidative balance-related exposures collectively affect risk for prostate cancer.

Dietary antioxidants and prostate cancer: a review

Prostate cancer is the most common noncutaneous cancer in men in the United States. Several studies have examined the relationship between prostate cancer and antioxidants; however, the results of these studies are inconsistent. This article provides a systematic review of studies on prostate cancer and antioxidant intake from diet and supplements. Tea and coffee appear to offer protection against advanced prostate cancer. Different forms of vitamin E appear to exert different effects on prostate cancer, with alpha-tocopherol potentially increasing and gamma-tocopherol potentially decreasing risk of the disease. There is no strong evidence for a beneficial effect of selenium, vitamin C, or beta-carotene, whereas lycopene appears to be negatively associated with risk of the disease. The effect of dietary antioxidants on prostate cancer remains undefined and inconclusive, with different antioxidants affecting prostate cancer risk differentially. Further studies are needed to clarify the relationship between antioxidants and prostate cancer risk and to delineate the underlying mechanisms.

Opposing roles of folate in prostate cancer

The US diet has been fortified with folic acid to prevent neural tube defects since 1998. The Physician Data Queries from the National Cancer Institute describe folate as protective against prostate cancer, whereas its synthetic analog, folic acid, is considered to increase prostate cancer risk when taken at levels easily achievable by eating fortified food or taking over-the-counter supplements. We review the present literature to examine the effects of folate and folic acid on prostate cancer, help interpret previous epidemiologic data, and provide clarification regarding the apparently opposing roles of folate for patients with prostate cancer. A literature search was conducted in Medline to identify studies investigating the effect of nutrition and specifically folate and folic acid on prostate carcinogenesis and progression. In addition, the National Health and Nutrition Examination Survey database was analyzed for trends in serum folate levels before and after mandatory fortification. Folate likely plays a dual role in prostate carcinogenesis. There remains conflicting epidemiologic evidence regarding folate and prostate cancer risk; however, there is growing experimental evidence that higher circulating folate levels can contribute to prostate cancer progression. Further research is needed to clarify these complex relationships.

Folate and B12 in prostate cancer

Mechanisms postulated to link folate and B12 metabolism with cancer, including genome-wide hypomethylation, gene-specific promoter hypermethylation, and DNA uracil misincorporation, have been observed in prostate tumor cells. However, epidemiological studies of prostate cancer risk, based on dietary intakes and blood levels of folate and vitamin B12 and on folate-pathway gene variants, have generated contradictory findings. In a meta-analysis, circulating concentrations of B12 (seven studies, OR = 1.10; 95% CI 1.01, 1.19; P = 0.002) and (in cohort studies) folate (five studies, OR = 1.18; 95% CI 1.00, 1.40; P = 0.02) were positively associated with an increased risk of prostate cancer. Homocysteine was not associated with risk of prostate cancer (four studies, OR = 0.91; 95% CI 0.69, 1.19; P = 0.5). In a meta-analysis of folate-pathway polymorphisms, MTR 2756A > G (eight studies, OR = 1.06; 95% CI 1.00, 1.12; P = 0.06) and SHMT1 1420C > T (two studies, OR = 1.11; 95% CI 1.00, 1.22; P = 0.05) were positively associated with prostate cancer risk. There were no effects due to any other polymorphisms, including MTHFR 677C > T (12 studies, OR = 1.04; 95% CI 0.97, 1.12; P = 0.3). The positive association of circulating B12 with an increased risk of prostate cancer could be explained by reverse causality. However, given current controversies over mandatory B12 fortification, further research to eliminate a causal role of B12 in prostate cancer initiation and/or progression is required. Meta-analysis does not entirely rule out a positive association of circulating folate with increased prostate cancer risk. As with B12, even a weak positive association would be a significant public health issue, given the high prevalence of prostate cancer and concerns about the potential harms versus benefits of mandatory folic acid fortification.

Folate intake, alcohol consumption, and the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism: influence on prostate cancer risk and interactions

Purpose: Folate is essential to DNA methylation and synthesis and may have a complex dualistic role in prostate cancer. Alcohol use may increase risk and epigenetic factors may interact with lifestyle exposures. We aimed to characterize the independent and joint effects of folate intake, alcohol consumption, and the MTHFR C677T gene polymorphism on prostate cancer risk, while accounting for intakes of vitamins B₂, B₆, B₁₂, methionine, total energy, and confounders. Methods: A case-control study was conducted at Kingston General Hospital of 80 incident primary prostate cancer cases and 334 urology clinic controls, all with normal age-specific PSA levels (to exclude latent prostate cancers). Participants completed a questionnaire on folate and alcohol intakes and potential confounders prior to knowledge of diagnosis, eliminating recall bias, and blood was drawn for MTHFR genotyping. Joint effects of exposures were assessed using unconditional logistic regression and significance of multiplicative and additive interactions using general linear models. Results: Folate, vitamins B₂, B₆, B₁₂, methionine, and the CT and TT genotypes were not associated with prostate cancer risk. The highest tertile of lifetime alcohol consumption was associated with increased risk (OR = 2.08; 95% CI: 1.12–3.86). Consumption of >5 alcoholic drinks per week was associated with increased prostate cancer risk among men with low folate intake (OR = 2.38; 95% CI: 1.01–5.57), and higher risk among those with the CC MTHFR genotype (OR = 4.43; 95% CI: 1.15–17.05). Increased risk was also apparent for average weekly alcohol consumption when accounting for the multiplicative interaction between folate intake and MTHFR C677T genotype (OR = 3.22; 95% CI: 1.36–7.59). Conclusion: Alcohol consumption is associated with increased prostate cancer risk, and this association is stronger among men with low folate intake, with the CC MTHFR genotype, and when accounting for the joint effect of folate intake and MTHFR C677T genotype.

Associations between Intake of Folate, Methionine, and Vitamins B-12, B-6 and Prostate Cancer Risk in American Veterans

Prostate cancer (PC) is the second leading cause of cancer death in men. Recent reports suggest that excess of nutrients involved in the one-carbon metabolism pathway increases PC risk; however, empirical data are lacking. Veteran American men (272 controls and 144 PC cases) who attended the Durham Veteran American Medical Center between 2004–2009 were enrolled into a case-control study. Intake of folate, vitamin B12, B6, and methionine were measured using a food frequency questionnaire. Regression models were used to evaluate the association among one-carbon cycle nutrients, MTHFR genetic variants, and prostate cancer. Higher dietary methionine intake was associated with PC risk (OR = 2.1; 95%CI 1.1–3.9) The risk was most pronounced in men with Gleason sum <7 (OR = 2.75; 95%CI 1.32– 5.73). The association of higher methionine intake and PC risk was only apparent in men who carried at least one MTHFR A1298C allele (OR = 6.7; 95%CI = 1.6–27.8), compared to MTHFR A1298A noncarrier men (OR = 0.9; 95%CI = 0.24–3.92) (p-interaction = 0.045). There was no evidence for associations between B vitamins (folate, B12, and B6) and PC risk. Our results suggest that carrying the MTHFR A1298C variants modifies the association between high methionine intake and PC risk. Larger studies are required to validate these findings.

Dietary fatty acid intake and prostate cancer survival in Örebro County, Sweden

Although dietary fat has been associated with prostate cancer risk, the association between specific fatty acids and prostate cancer survival remains unclear. Dietary intake of 14 fatty acids was analyzed in a population-based cohort of 525 Swedish men with prostate cancer in Örebro County (1989-1994). Multivariable hazard ratios and 95% confidence intervals for time to prostate cancer death by quartile and per standard deviation increase in intake were estimated by Cox proportional hazards regression. Additional models examined the association by stage at diagnosis (localized: T0-T2/M0; advanced: T0-T4/M1, T3-T4/M0). Among all men, those with the highest omega-3 docosahexaenoic acid and total marine fatty acid intakes were 40% less likely to die from prostate cancer (P(trend) = 0.05 and 0.04, respectively). Among men with localized prostate cancer, hazard ratios of 2.07 (95% confidence interval: 0.93, 4.59; P(trend) = 0.03) for elevated total fat, 2.39 (95% confidence interval: 1.06, 5.38) for saturated myristic acid, and 2.88 (95% confidence interval: 1.24, 6.67) for shorter chain (C4-C10) fatty acid intakes demonstrated increased risk for disease-specific mortality for the highest quartile compared with the lowest quartile. This study suggests that high intake of total fat and certain saturated fatty acids may worsen prostate cancer survival, particularly among men with localized disease. In contrast, high marine omega-3 fatty acid intake may improve disease-specific survival for all men.

Relationship between dietary factors and prostate-specific antigen in healthy men

INTRODUCTION

There is little evidence indicating whether dietary factors influence prostate-specific antigen (PSA) concentrations. We examined whether nutritional factors, including energy, protein, fat, and carbohydrate intake were associated with PSA in healthy men.

SUBJECTS AND METHODS

We investigated 13,594 men aged 50 years and over who visited a hospital for a routine health checkup between 2003 and 2007. Dietary intake was assessed using a food frequency questionnaire. We performed a multiple linear regression to examine the association between PSA and dietary intake.

RESULTS

After controlling for age, body mass index, and physical activity, PSA was significantly negatively associated with percent protein intake (p for trend < 0.001). Compared with the lowest quintile, PSA was 5.8% lower (95% CI: -8.9 to -2.5%) in the highest quintile. We also observed a significant positive association between percent fat intake and PSA concentration (p for trend 0.043). PSA was 3.4% greater (95% CI: 0-6.9%) among men in the highest quintile compared with those in the lowest quintile.

CONCLUSIONS

Men who had a lower percent protein intake and higher percent fat intake had an elevated PSA level, although the magnitude of these associations was small.

The effect of age on 12 chemical element contents in the intact prostate of adult men investigated by inductively coupled plasma atomic emission spectrometry

The effect of age on 12 chemical element contents in intact prostate of 64 apparently healthy, 13-60-year-old men (mean age 36.5 years) was investigated by inductively coupled plasma atomic emission spectrometry. Mean values (M ± SΕΜ) for mass fraction (milligrams/kilogram, on dry weight basis) of Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, and Zn were: Ba 1.18 ± 0.12, Ca 2,178 ± 160, Cu 10.7 ± 0.9, Fe 122 ± 5, K 12,530 ± 360, Mg 1,100 ± 70, Na 10,470 ± 320, P 7,580 ± 300, S 8,720 ± 180, Sr 1.85 ± 0.28, and Zn 782 ± 97, respectively. The upper limit of mean content of V was ≤0.22 mg/kg. A tendency of age-related increase in Ca, Fe, Na, and Zn mass fraction as well an increase in Zn/Ba, Zn/Ca, Zn/Cu, Zn/Fe, Zn/K, Zn/Mg, Zn/Na, Zn/P, Zn/S, and Zn/Sr ratios in prostate was observed. A significant positive correlation was seen between the prostatic zinc and Ca, Cu, Fe, Mg, Na, and P contents.

Dietary intake of B vitamins and methionine and prostate cancer incidence and mortality

PURPOSE

We investigated prospectively the relationship between dietary intakes of methionine, B vitamins associated with one-carbon metabolism, and risk of incident and fatal prostate cancer.

METHODS

The Melbourne Collaborative Cohort Study recruited 41,514 people aged 40-69 years between 1990 and 1994. During follow-up of 14,620 men for 15 years on average, we ascertained 1,230 incident prostate cancers and 114 prostate cancer deaths. Dietary intakes were estimated using a 121-item food frequency questionnaire. Hazard ratios (HR) and 95 % confidence intervals were estimated using Cox regression.

RESULTS

For overall prostate cancer incidence, HRs for riboflavin intake were significantly increased relative to quintile 1 (except quintile 5), with a peak for quintile 3, HR 1.29 (1.07, 1.57). A similar but non-statistically significant pattern existed between riboflavin intake and prostate cancer mortality. The HR for folate intake and overall incidence was significantly increased for quintile 4, HR 1.21 (1.01, 1.46). No association was observed between prostate cancer mortality and the intake of either folate or any other B vitamin or methionine, and no observed association varied by tumor aggressiveness (all P(homogeneity) > 0.1).

CONCLUSIONS

We found little evidence of association between dietary intakes of B vitamins or methionine and prostate cancer risk. Weak associations between prostate cancer incidence and dietary intake of riboflavin and folate, and between riboflavin intake and prostate cancer mortality, need corroboration by other studies.

Serum retinol and risk of prostate cancer

Greater exposure to retinol (vitamin A) may prevent prostate cancer, although under some conditions it could promote cell growth and de-differentiation. The authors prospectively examined prostate cancer risk and serum retinol levels, measured by using high-performance liquid chromatography, at baseline (n = 29,104) and after 3 years (n = 22,843) in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort. Cox proportional hazards models were used to estimate the relative risk of total (n = 2,041) and aggressive (n = 461) prostate cancer by quintiles of baseline and 3-year serum retinol concentrations and by change in serum retinol levels from baseline to 3 years. Men with higher retinol concentrations at baseline were more likely to develop prostate cancer (quintile 5 vs. quintile 1 hazard ratio = 1.19, 95% confidence interval: 1.03, 1.36; P(trend) = 0.009). The results were similar for aggressive disease. Joint categorization based on baseline and 3-year retinol levels showed that men who were in the highest quintile at both time points had the greatest increased risk (baseline/3-year quintile 5/quintile 5 vs. quintile 1/quintile 1 hazard ratio = 1.31, 95% confidence interval: 1.08, 1.59). In this largest study to date of vitamin A status and subsequent risk of prostate cancer, higher serum retinol was associated with elevated risk, with sustained high exposure conferring the greatest risk. Future studies may clarify the underlying biologic mechanisms of the retinol-prostate cancer association.

Dietary zinc and prostate cancer survival in a Swedish cohort

BACKGROUND

Zinc is involved in many essential cellular functions, including DNA repair and immune system maintenance. Although experimental evidence supports a role for zinc in prostate carcinogenesis, epidemiologic data are inconsistent; no data on cancer-specific survival have been reported.

OBJECTIVE

Our objective was to determine whether dietary zinc assessed near the time of prostate cancer diagnosis is associated with improved disease-specific survival.

DESIGN

This population-based cohort consists of 525 men aged <80 y from Örebro County, Sweden, with a diagnosis of prostate cancer made between 1989 and 1994. Study participants completed self-administered food-frequency questionnaires, and zinc intake was derived from nutrient databases. Cox proportional hazards regression was used to estimate multivariate hazard ratios (HRs) and 95% CIs for time to death from prostate cancer as well as death from all causes through February 2009 by quartile (Q) of dietary zinc intake. Models were also stratified by disease stage at diagnosis (localized or advanced).

RESULTS

With a median follow-up of 6.4 y, 218 (42%) men died of prostate cancer and 257 (49%) died of other causes. High dietary zinc intake was associated with a reduced risk of prostate cancer-specific mortality (HR(Q4 vs Q1): 0.64; 95% CI: 0.44, 0.94; P for trend = 0.05) in the study population. The association was stronger in men with localized tumors (HR: 0.24; 95% CI: 0.09, 0.66; P for trend = 0.005). Zinc intake was not associated with mortality from other causes.

CONCLUSION

These results suggest that high dietary intake of zinc is associated with lower prostate cancer-specific mortality after diagnosis, particularly in men with localized disease.

The effect of age on Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn contents in intact human prostate investigated by neutron activation analysis

The effect of age on trace element contents in intact prostate of 64 apparently healthy 13-60 years old men was investigated by neutron activation analysis. Mean values (M±SΕΜ) for content (mg/kg, dry weight basis) of trace elements were: Ag-0.057±0.007, Co-0.036±0.003, Cr-0.48±0.06, Fe-96.9±6.2, Hg-0.045±0.006, Rb-12.5±0.6, Sb-0.050±0.005, Sc-0.020±0.003, Se-0.63±0.03, and Zn-548±55, respectively. A tendency of age-related increase in Co, Fe, Hg, Sc, and Zn content was observed.

Associations of circulating and dietary vitamin D with prostate cancer risk: a systematic review and dose-response meta-analysis

OBJECTIVE

We systematically reviewed and meta-analyzed literature examining associations of vitamin D (dietary intake, circulating 25-hydroxy-vitamin-D (25(OH)D), and 1,25-dihydroxy-vitamin-D (1,25(OH)(2)D) concentrations) with prostate cancer.

METHODS

We searched over 24,000 papers from seven electronic databases (to October 2010) for exposures related to vitamin D. We conducted dose-response random-effects meta-analyses pooling the log odds ratio (OR) and 95% confidence intervals (CI) per change in natural units of each exposure. The I(2) statistic quantified between-study variation due to heterogeneity.

RESULTS

Twenty-five papers were included. In prospective studies, the OR per 1,000 IU increase in dietary intake was 1.14 (6 studies; CI: 0.99, 1.31; I (2) = 0%) for total prostate cancer and 0.93 (3 studies; 0.63, 1.39; I (2) = 25%) for aggressive prostate cancer. Five case-control studies examined dietary intake, but there was a high degree of inconsistency between studies (I (2) = 49%). The OR per 10 ng/mL increase in 25(OH)D was 1.04 (14 studies; 0.99, 1.10; I (2) = 0%) for total prostate cancer and 0.98 (6 studies; 0.84, 1.15; I (2) = 32%) for aggressive prostate cancer. The OR per 10 pg/mL increase in 1,25(OH)(2)D was 1.00 (7 studies; 0.87, 1.14; I (2) = 41%) for total prostate cancer and 0.86 (2 studies; 0.72, 1.02; I (2) = 0%) for aggressive prostate cancer.

CONCLUSION

Published literature provides little evidence to support a major role of vitamin D in preventing prostate cancer or its progression.

Seaweed proteins and amino acids as nutraceuticals

Seaweeds demonstrate original and interesting nutritional characteristics. Protein concentration ranges from 5% to 47% of dry basic. Its value depends particularly on species and the environmental conditions. Seaweed protein is a source of all amino acids, especially glycine, alanine, arginine, proline, glutamic, and aspartic acids. In algae, essential amino acids (EAAs) represent almost a half of total amino acids and their protein profile is close to the profile of egg protein. In case of non-EAAs, all three groups (green, brown, and red seaweeds) contain the similar amount. Red seaweed seems to be a good source of protein because its value reaches 47%. The issue of protein malnutrition supports the trend to find a new and cheap alternative source of protein. Algae could play an important role in the above-mentioned challenge because of relatively high content of nitrogen compounds. Algae may be used in the industry as a source of ingredients with high nutritional quality.

Effect of oxidative damage due to excessive protein ingestion on pancreas function in mice

The present study was undertaken to evaluate the effect of oxidative damage due to excessive protein diet on pancreas function in mice. For this purpose, thirty male (C57BL/6J) mice were randomly divided into three groups and fed on different diets as follows: group 1 was fed on a normal diet, group 2 was fed on an excessive protein diet and group 3 was fed on an excessive protein diet supplemented with 0.06 g/kg cysteamine. Each group was fed for 2 weeks, and then pancreas samples were collected to examine oxidative and antioxidant parameters and pancreas function. The results showed that ingestion of an excessive protein diet markedly increased contents of malondialdehyde (MDA) and decreased T-AOC and activities of antioxidants SOD and GSH-Px, compared with a normal diet (P < 0.05). Pancreas weight and concentration of protein, DNA and RNA were significantly higher (P < 0.05), digestive enzyme activities were significantly lower and levels of somatostatin and insulin were higher in mice fed with an excessive protein diet than those fed with a normal protein diet. In the group fed with excessive protein diet supplemented with cysteamine, oxidative stress was mitigated and pancreas function was improved. These data demonstrate that excessive protein ingestion could increase oxidative damage of free radicals on pancreas function through destroying the balance of oxidants and antioxidants.

Interaction between the MTHFR C677T Polymorphism and Alcohol—Impact on Oral Cancer Risk and Multiple DNA Methylation of Tumor-related Genes

Several studies have reported Oral Squamous Cell Carcinoma ( OSCC) association with etiological factors, such as smoking and alcohol. The aim of the present study was to establish whether the methylenetetrahydrofolate reductase ( MTHFR) C677T genotype and a high alcohol intake, solely or in interaction, have an impact on the oral cancer risk, DNA methylation, or multiple methylation of tumor-related genes. MTHFR C677T genetic polymorphism was determined by the PCR/RFLP method, and DNA methylation was assessed by nested methylation-specific PCR. The risk for multiple methylation was significantly increased in heavy-drinking patients with the TT genotype, compared with CC and CT patients (OR = 10.873; 95% CI, 1.134-104.24). Multiple methylation was significantly associated with tumor stage ( p = 0.018), and showed a trend of association with the presence of nodal metastases ( p = 0.058). A significant association was found between TT genotype and methylation status of the RASSF1A gene in OSCC patients ( p = 0.012). Heavy-drinking individuals with the TT genotype showed increased oral cancer risk compared with the CC genotype (OR = 3.601; 95% CI, 1.036-12.513), and compared with the CC and CT genotypes (OR = 4.288; 95% CI, 1.325-13.877). Our study suggested gene-environment interactions between high alcohol intake and the MTHFR 677TT genotype for elevated oral cancer risk, with a significant impact on multiple methylation of cancer-related genes.

Dietary folate intake and the risk of 11 types of cancer: a case-control study in Uruguay

BACKGROUND

There is limited, but inconclusive, epidemiological evidence that high folate intake decreases the risk of colorectal and esophageal cancers. For other cancer sites, the evidence is even less consistent or extensive.

MATERIALS AND METHODS

We conducted a case-control study of dietary folate intake and risk of 11 cancer sites in Uruguay between 1996 and 2004, including 3539 cancer cases and 2032 hospital controls. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of cancer associated with folate intake.

RESULTS

In the multivariable model, there was a significant decrease in the risk of cancers of the oral cavity and pharynx (OR = 0.49, 95% CI 0.24-0.98), esophagus (OR = 0.29, 95% CI 0.14-0.60), upper aerodigestive tract (OR = 0.41, 95% CI 0.26-0.65), colorectum (OR = 0.42, 95% CI 0.23-0.76) and kidney (OR = 0.35, 95% CI 0.13-0.93) for the highest versus the lowest quartile of dietary folate intake.

CONCLUSIONS

Our results not only confirm earlier findings of decreased risk of colorectal and esophageal cancers with a high dietary folate intake but also suggest decreased risk of several other cancers. However, we cannot exclude the possibility that residual confounding, multiple comparisons or other forms of bias could explain these results.

Diet and prostate cancer risk with specific focus on dairy products and dietary calcium: a case-control study

BACKGROUND

Despite the prevalence of prostate cancer worldwide, only a few risk factors have been well-established. The role of diet, especially of dairy products, in the etiology of prostate cancer is still controversial.

METHODS

This study assessed the association of dietary components, particularly dairy products and dietary calcium, on prostate cancer risk in a case-control study of 197 cases and an equal number of individually matched controls recruited in Montreal, Canada. A semi-quantitative food frequency questionnaire was administered in which the usual consumption frequency and amounts consumed of more than 200 food items were recorded.

RESULTS

We found a twofold increased risk of prostate cancer associated with an increased intake of dairy products {Odds Ratio (OR) = 2.19; 95% Confidence Intervals (CI) 1.22-3.94}. A significant trend of decreasing prostate cancer risk with higher intake was found for legumes, nuts, finfish/shellfish and for alpha-tocopherol after adjustment for calcium intake. Milk was the only dairy product significantly associated with prostate cancer risk, with OR = 2.27; 95% CI (1.25-4.09) for the highest versus lowest quartiles of consumption. Calcium, the main micronutrient contained in dairy products, showed only a borderline association with prostate cancer risk (P = 0.09), with slightly higher risk for higher calcium intake. In conclusion, this study supports the hypothesis that dairy products, especially milk, are involved in the etiology of prostate cancer. However, the mechanisms by which the various nutrients in dairy products and total diet may interact to influence this risk remain unknown.

Circulating folate, vitamin B12, homocysteine, vitamin B12 transport proteins, and risk of prostate cancer: a case-control study, systematic review, and meta-analysis

BACKGROUND

Disturbed folate metabolism is associated with an increased risk of some cancers. Our objective was to determine whether blood levels of folate, vitamin B(12), and related metabolites were associated with prostate cancer risk.

METHODS

Matched case-control study nested within the U.K. population-based Prostate testing for cancer and Treatment (ProtecT) study of prostate-specific antigen-detected prostate cancer in men ages 50 to 69 years. Plasma concentrations of folate, B(12) (cobalamin), holo-haptocorrin, holo-transcobalamin total transcobalamin, and total homocysteine (tHcy) were measured in 1,461 cases and 1,507 controls. ProtecT study estimates for associations of folate, B(12), and tHcy with prostate cancer risk were included in a meta-analysis, based on a systematic review.

RESULTS

In the ProtecT study, increased B(12) and holo-haptocorrin concentrations showed positive associations with prostate cancer risk [highest versus lowest quartile of B(12) odds ratio (OR) = 1.17 (95% confidence interval, 0.95-1.43); P(trend) = 0.06; highest versus lowest quartile of holo-haptocorrin OR = 1.27 (1.04-1.56); P(trend) = 0.01]; folate, holo-transcobalamin, and tHcy were not associated with prostate cancer risk. In the meta-analysis, circulating B(12) levels were associated with an increased prostate cancer risk [pooled OR = 1.10 (1.01-1.19) per 100 pmol/L increase in B(12); P = 0.002]; the pooled OR for the association of folate with prostate cancer was positive [OR = 1.11 (0.96-1.28) per 10 nmol/L; P = 0.2) and conventionally statistically significant if ProtecT (the only case-control study) was excluded [OR = 1.18 (1.00-1.40) per 10 nmol/L; P = 0.02].

CONCLUSION

Vitamin B(12) and (in cohort studies) folate were associated with increased prostate cancer risk.

IMPACT

Given current controversies over mandatory fortification, further research is needed to determine whether these are causal associations.

Cancer-preventive activities of tocopherols and tocotrienols

The cancer-preventive activity of vitamin E has been studied. Whereas some epidemiological studies have suggested a protective effect of vitamin E against cancer formation, many large-scale intervention studies with alpha-tocopherol (usually large doses) have not demonstrated a cancer-preventive effect. Studies on alpha-tocopherol in animal models also have not demonstrated robust cancer prevention effects. One possible explanation for the lack of demonstrable cancer-preventive effects is that high doses of alpha-tocopherol decrease the blood and tissue levels of delta-tocopherols. It has been suggested that gamma-tocopherol, due to its strong anti-inflammatory and other activities, may be the more effective form of vitamin E in cancer prevention. Our recent results have demonstrated that a gamma-tocopherol-rich mixture of tocopherols inhibits colon, prostate, mammary and lung tumorigenesis in animal models, suggesting that this mixture may have a high potential for applications in the prevention of human cancer. In this review, we discuss biochemical properties of tocopherols, results of possible cancer-preventive effects in humans and animal models and possible mechanisms involved in the inhibition of carcinogenesis. Based on this information, we propose that a gamma-tocopherol-rich mixture of tocopherols is a very promising cancer-preventive agent and warrants extensive future research.

Management of anaemia in prostate cancer

Anaemia is a frequent complication of prostate cancer and of its treatments. In Europe prostate cancer accounts for the 10.8% of all malignant neoplasms. Iatrogenic hypogonadism and age-related physiologic changes along with nutritional deficits contribute to increase prevalence of prostate cancer related anaemia. The reason of the present review is to provide clinicians with all aspects of a frequent and multifactorial co-morbidity, whose effects are often underestimated. Erythropoiesis pathology and causes of anaemia in prostate cancer are reviewed. Critical issues of clinical management of anaemia in prostate cancer are discussed.

Dietary vitamins E and C and prostate cancer risk

BACKGROUND

The epidemiologic evidence on dietary vitamins E and C and prostate cancer is controversial. Therefore, a case-control study was carried out to investigate the role of dietary intake of vitamins E and C in the etiology of prostate cancer.

MATERIAL AND METHODS

Cases were 1 294 men with incident, histologically confirmed prostate cancer, admitted to the major teaching and general hospitals of five Italian areas between 1991 and 2002. Controls were 1 451 men admitted for acute, non-neoplastic conditions to the same hospitals. Information on dietary habits and nutrient intake was elicited using a validated food frequency questionnaire including 78 food groups and recipes. Odds ratios (OR) and 95% confidence intervals (CI) for increasing levels of vitamin intake were estimated after allowance for total energy intake and other confounding factors.

RESULTS

Vitamin E showed a significant inverse association with prostate cancer (OR = 0.78 for the highest versus the lowest tertile of intake, 95% CI: 0.58-0.96; p-value for trend = 0.02), whereas for vitamin C the inverse association was of borderline statistical significance (OR = 0.86; 95% CI: 0.65-1.08). Results were consistent in strata of age, body mass index, and family history of prostate cancer.

DISCUSSION

The present study shows an inverse association between dietary intake of vitamins E and prostate cancer incidence. This finding is likely to reflect the influence of diet itself since supplementation or food fortification with vitamins is rare in the Italian population.

Dietary fat and early-onset prostate cancer risk

The UK incidence of prostate cancer has been increasing in men aged < 60 years. Migrant studies and global and secular variation in incidence suggest that modifiable factors, including a high-fat diet, may contribute to prostate cancer risk. The aim of the present study was to investigate the role of dietary fat intake and its derivatives on early-onset prostate cancer risk. During 1999-2004, a population-based case-control study with 512 cases and 838 controls was conducted. Cases were diagnosed with prostate cancer when < or = 60 years. Controls were sourced from UK GP practice registers. A self-administered FFQ collected data on typical past diet. A nutritional database was used to calculate daily fat intake. A positive, statistically significant risk estimate for the highest v. lowest quintile of intake of total fat, SFA, MUFA and PUFA was observed when adjusted for confounding variables: OR 2.53 (95 % CI 1.72, 3.74), OR 2.49 (95 % CI 1.69, 3.66), OR 2.69 (95 % CI 1.82, 3.96) and OR 2.34 (95 % CI 1.59, 3.46), respectively, with all P for trend < 0.001. In conclusion, there was a positive statistically significant association between prostate cancer risk and energy-adjusted intake of total fat and fat subtypes. These results potentially identify a modifiable risk factor for early-onset prostate cancer.

Intake of folate, vitamins B6, B12 and methionine and risk of pancreatic cancer in a large population-based case-control study

OBJECTIVE

Folate and other methyl-group nutrients may play a key role in pancreatic carcinogenesis through their effects on DNA integrity. We examined the association between pancreatic cancer and intake of folate, vitamins B(6), B(12) and methionine in a large population-based case-control study.

METHODS

Risk factor data were collected during in-person interviews with 532 pancreatic cancer cases diagnosed in 1995-1999 and 1,701 frequency-matched controls in the San Francisco Bay Area. Dietary history and supplement use were obtained using a semi-quantitative food-frequency questionnaire developed at Harvard University. Adjusted unconditional logistic regression was used to compute odds ratios (OR) and 95% confidence intervals (CI) as estimates of the relative risk.

RESULTS

Total folate intake was inversely associated with pancreatic cancer (5th vs. 1st quintile: OR = 0.67, 95% CI = 0.48-0.93, p (trend) = 0.04). Increased vitamin B(12) from food was positively associated with pancreatic cancer although risk estimates for quintiles 3-5 were similar (5th vs. 1st quintile: OR = 1.9, 95% CI = 1.3-2.6, p (trend) = 0.001). Intake of vitamin B(6) or methionine was not associated with pancreatic cancer risk.

CONCLUSIONS

Our study provided some support for an inverse association between folate intake and pancreatic cancer risk. The increased pancreatic cancer risk with vitamin B(12) intake from food warrants further investigation.

One-carbon metabolism-related nutrients and prostate cancer survival

BACKGROUND

Folate and other one-carbon metabolism nutrients may influence prostate cancer pathogenesis. Prior studies of these nutrients in relation to prostate cancer incidence have been inconclusive, and none have explored prostate cancer survival.

OBJECTIVE

The objective was to assess whether dietary intakes of folate, riboflavin, vitamin B-6, vitamin B-12, and methionine measured around the time of prostate cancer diagnosis are associated with prostate cancer survival.

DESIGN

This population-based prospective study comprised 525 men from Orebro, Sweden, who received a diagnosis of incident prostate cancer between 1989 and 1994 and completed a self-administered food-frequency questionnaire. Record linkages to the Swedish Death Registry enabled all cases to be followed for up to 20 y after diagnosis, and the cause of death was assigned via medical record review. Cox proportional hazards regression was used to calculate multivariable hazard ratios (HRs) and 95% CIs. During a median of 6.4 y of follow-up, 218 men (42%) died of prostate cancer and 257 (49%) of other causes.

RESULTS

A comparison of the highest with the lowest quartile showed that vitamin B-6 intake was inversely associated with prostate cancer-specific death (HR: 0.71; 95% CI: 0.46, 1.10; P for trend = 0.08), especially in men with a diagnosis of localized-stage disease (HR; 0.05; 95% CI: 0.01, 0.26; P for trend = 0.0003). However, vitamin B-6 intake was not associated with improved prostate cancer survival among advanced-stage cases (HR: 1.04; 95% CI: 0.64, 1.72; P for trend = 0.87). Folate, riboflavin, vitamin B-12, and methionine intakes were not associated with prostate cancer survival.

CONCLUSION

A high vitamin B-6 intake may improve prostate cancer survival among men with a diagnosis of localized-stage disease.