Retinol, vitamins A, C, and E and breast cancer risk: a meta-analysis and meta-regression

Non-genetic factors and breast cancer: an umbrella review of meta-analyses

BACKGROUND

Previous research has found associations between various non-genetic factors and breast cancer (BrCa) risk. This study summarises and appraises the credibility of the available evidence on the association between non-genetic factors and BrCa risk.

METHODS

We conducted an umbrella review of meta-analyses. Medline, Scopus, and the Cochrane databases were systematically searched for meta-analyses examining non-genetic factors and BrCa incidence or mortality. The strength of the evidence was graded in four categories (i.e., weak, suggestive, highly suggestive, convincing).

RESULTS

A total of 781 meta-analyses from 280 publications were evaluated and graded. We included exposures related to anthropometric measurements, biomarkers, breast characteristics and diseases, diet and supplements, environment, exogenous hormones, lifestyle and social factors, medical history, medication, reproductive history, and pregnancy. The largest number of examined associations was found for the category of diet and supplements and for exposures such as aspirin use and active smoking. The statistically significant (P-value < 0.05) meta-analyses were 382 (49%), of which 204 (53.4%) reported factors associated with increased BrCa risk. Most of the statistically significant evidence (n = 224, 58.6%) was graded as weak. Convincing harmful associations with heightened BrCa risk were found for increased body mass index (BMI), BMI and weight gain in postmenopausal women, oral contraceptive use in premenopausal women, increased androstenedione, estradiol, estrone, and testosterone concentrations, high Breast Imaging Reporting and Data System (BIRADS) classification, and increased breast density. Convincing protective factors associated with lower BrCa risk included high fiber intake and high sex hormone binding globulin (SHBG) levels while highly suggestive protective factors included high 25 hydroxy vitamin D [25(OH)D] levels, adherence to healthy lifestyle, and moderate-vigorous physical activity.

CONCLUSIONS

Our findings suggest some highly modifiable factors that protect from BrCa. Interestingly, while diet was the most studied exposure category, the related associations failed to reach higher levels of evidence, indicating the methodological limitations in the field. To improve the validity of these associations, future research should utilise more robust study designs and better exposure assessment techniques. Overall, our study provides knowledge that supports the development of evidence-based BrCa prevention recommendations and guidance, both at an individual level and for public health initiatives.

TRIAL REGISTRATION

PROSPERO CRD42022370675.

Association between consumption of small fish and all-cause mortality among Japanese: the Japan Multi-Institutional Collaborative Cohort Study

OBJECTIVE

Although small fish are an important source of micronutrients, the relationship between their intake and mortality remains unclear. This study aimed to clarify the association between intake of small fish and all-cause and cause-specific mortality.

DESIGN

We used the data from a cohort study in Japan. The frequency of the intake of small fish was assessed using a validated FFQ. The hazard ratio (HR) and 95 % confidence interval (CI) for all-cause and cause-specific mortality according to the frequency of the intake of small fish by sex were estimated using a Cox proportional hazard model with adjustments for covariates.

SETTING

The Japan Multi-Institutional Collaborative Cohort Study.

PARTICIPANTS

A total of 80 802 participants (34 555 males and 46 247 females), aged 35-69 years.

RESULTS

During a mean follow-up of 9·0 years, we identified 2482 deaths including 1495 cancer-related deaths. The intake of small fish was statistically significantly and inversely associated with the risk of all-cause and cancer mortality in females. The multivariable-adjusted HR (95 % CI) in females for all-cause mortality according to the intake were 0·68 (0·55, 0·85) for intakes 1-3 times/month, 0·72 (0·57, 0·90) for 1-2 times/week and 0·69 (0·54, 0·88) for ≥ 3 times/week, compared with the rare intake. The corresponding HR (95 % CI) in females for cancer mortality were 0·72 (0·54, 0·96), 0·71 (0·53, 0·96) and 0·64 (0·46, 0·89), respectively. No statistically significant association was observed in males.

CONCLUSIONS

Intake of small fish may reduce the risk of all-cause and cancer mortality in Japanese females.

Vitamin E - a scoping review for Nordic Nutrition Recommendations 2023

Current evidence suggests that dietary vitamin E (as α-tocopherol) intake has a beneficial role in preventing certain chronic diseases. In contrast, there is no clear evidence for the benefit of α-tocopherol supplements in a generally healthy population. Deficiency symptoms are rare and mainly occur due to genetic or other factors affecting α-tocopherol absorption and/or metabolism, rather than a low α-tocopherol intake. No qualified systematic review was identified by the NNR2023 project for updating the dietary reference values (DRV).

Relationship between food-derived antioxidant vitamin intake and breast cancer risk: a mendelian randomized study

BACKGROUND

In previous observational studies, food-derived antioxidant vitamins have been suggested to be associated with breast cancer. However, the findings were inconsistent and the causal relationship could not be clearly elucidated. To confirm the potential causal relationship between food-derived antioxidants (retinol, carotene, vitamin C and vitamin E) and the risk of breast cancer, we conducted a two-sample Mendelian randomization (MR) study.

METHODS

The instrumental variables (IVs) as proxies of genetic liability to food-derived antioxidant vitamins were obtained from the UK Biobank Database. We extracted breast cancer data (122,977 cases and 105,974 controls) from the Breast Cancer Consortium (BCAC). In addition, we studied estrogen expression status categorically, including estrogen receptor positive (ER+) breast cancer (69,501 cases and 105,974 controls) and versus estrogen receptor (ER-) negative breast cancer (21,468 cases and 105,974 controls). We performed two-sample Mendelian randomization study, and inverse variance-weighted (IVW) test was regarded as main analysis. Sensitivity analyses were further conducted to assess heterogeneity and horizontal pleiotropy.

RESULTS

The results of IVW showed that among the four food-derived antioxidants, only vitamin E had protective effect on the risk of overall breast cancer (OR = 0.837, 95% CI 0.757-0.926, P = 0.001) and ER+ breast cancer (OR = 0.823, 95% CI 0.693-0.977, P = 0.026). However, we found no association between food-derived vitamin E and ER- breast cancer.

CONCLUSIONS

Our study suggested food-derived vitamin E can decrease the risk of breast cancer overall and ER+ breast cancer, and the robustness of our results was confirmed by sensitivity analyses.

Vitamin E intake and multiple health outcomes: an umbrella review

Background

The benefits of vitamin E (VE) for multiple health outcomes have been well evaluated in many recent studies.

Objective

The purpose of this umbrella review was to conduct a systematic evaluation of the possible associations between VE intake and various health outcomes.

Methods

We systematically searched various databases, such as PubMed, Embase, and the Web of Science, to identify related meta-analyses of observational studies and randomized trials. We estimated the effect size of each association by using the random or fixed effects models and the 95% confidence intervals. We used standard approaches to evaluate the quality of the articles (AMSTAR) and classified the evidence into different levels of quality (GRADE).

Results

A total of 1,974 review articles were searched, and 27 articles with 28 health outcomes were yielded according to our exclusion criteria. The intake of VE was inversely associated with the risk of breast cancer, lung cancer, esophageal cancer, gastric cancer, pancreatic cancer, kidney cancer, bladder cancer, cervical neoplasms, cardiovascular disease, Parkinson's disease, depression, age-related cataracts, metabolic syndrome, and fracture. Overall, most of the quality of the evidence was low or very low. Three outcomes (stroke, age-related cataracts, obesity) were identified as having a "moderate" level of quality. The AMSTAR scores for all health outcomes ranged from 5 to 10.

Conclusion

Our study revealed that VE intake is beneficially related to multiple health outcomes. However, future studies on recommended doses and recommended populations of VE are also needed.

Systematic review registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022339571.

Association between pre-diagnostic dietary antioxidant vitamin consumption and ovarian cancer survival: a prospective cohort study

Background: Epidemiological evidence regarding the relationship between dietary antioxidant vitamin intake and ovarian cancer (OC) survival is not clear. Herein, we aimed to first evaluate this topic in a prospective cohort study in China. Methods: The present study included participants from the Ovarian Cancer Follow-Up Study, which was a hospital-based prospective cohort study including OC patients who were aged 18 to 79 years during 2015-2020. The information on the intake of antioxidant vitamins, consisting of vitamin A, retinol, α-carotene, β-carotene, vitamin C, and vitamin E, and other diet information was obtained through a 111-item food frequency questionnaire. Deaths were recorded until March 31, 2021. Hazard ratios (HRs) and 95% confidence intervals (CIs) for overall survival were evaluated using Cox proportional hazards models. Results: There were 130 (18.49%) deaths among 703 OC patients during a median 37.19 months follow-up. In the multivariable-adjusted model, the highest tertile of dietary vitamin C (HR = 0.43, 95% CI = 0.25-0.75, P for trend <0.05) and β-carotene intake (HR = 0.52, 95% CI = 0.31-0.87, P for trend <0.05) was inversely associated with the overall survival of OC when compared with the lowest tertile group. Retinol, vitamin A, vitamin E, and α-carotene consumption showed no association with OC survival. Of note is that the multiplicative interaction was identified between vitamin C intake and residual lesions in OC survival (P for interaction <0.05). Conclusion: Our findings indicate that pre-diagnostic higher vitamin C and β-carotene intake was associated with improved OC survival.

Retinoids in cancer chemoprevention and therapy: Meta-analysis of randomized controlled trials

Retinoids, natural and synthetic derivatives of vitamin A, have many regulatory functions in human body, including regulating cellular proliferation, differentiation, apoptosis. Moreover, retinoids have been used successfully for the treatment of certain malignancies, especially acute promyelocytic leukemia (APL) in adults and neuroblastoma in children. However, retinoids have not yet been translated into effective systemic treatments for most solid cancers. Some recent studies have shown that retinoids promote tumorigenesis. Therefore, we performed this meta-analysis to systematically evaluate the efficacy of retinoids in the chemoprevention and treatment of cancers. We performed literature search of several electronic databases, including PubMed, Embase and Cochrane Library from 2000 January to 2021 November. Various outcomes were applied to investigate the potential of retinoids for prevention and treatment of cancers. The primary outcomes in this study were disease recurrence and clinical response. The secondary outcomes included overall survival (OS), cancer development, disease progression and event-free survival. We identified 39 randomized controlled trials with 15,627 patients in this study. Our results showed that lower recurrence rate and better clinical response were obtained in retinoids treated patients with cancer or premalignancy as compared with control. The differences were statistically significant (RR = 0.85, 95% CI = 0.74-0.96, p = 0.01; RR = 1.24, 95% CI = 1.03-1.49, p = 0.02, respectively). Retinoids treatment was not associated with improvement in overall survival, cancer development, disease progression or event-free survival. Subgroup analysis conducted based on cancer type showed that patients benefited from retinoids treatment in APL, renal cell carcinoma, hepatocellular carcinoma, lung cancer, Kaposi sarcoma, and complete hydatidiform mole. No significant therapeutic effect was noted in head and neck cancer, acute myeloid leukemia (AML), melanoma, breast cancer, bladder cancer, cervical intraepithelial neoplasia (CIN) or cervical carcinoma. Subgroup analysis based on tumor classification demonstrated that retinoids group obtained a lower recurrence rate and better clinical response than control group in solid cancers. In conclusion, clinical application of retinoids was associated with reduction in disease recurrence and improvement in clinical response, illustrating that retinoids play a key role in cancer prevention and therapy. Further research is needed to broaden the utility of retinoids in other types of cancers. Systematic Review Registration: PROSPERO, identifier CRD42022296706.

Dietary Vitamin A Intake and Circulating Vitamin A Concentrations and the Risk of Three Common Cancers in Women: A Meta-Analysis

BACKGROUND

According to relevant clinical research, dietary and circulating antioxidants vitamin A are connected with the risk of breast, cervical, and ovarian cancer in women. However, there was inconsistency between the findings. We completed this meta-analysis at the right moment to address this contradiction of the problem.

METHODS

Web of Science, Embase, and PubMed databases were searched using the proposed search strategy and filtered using the inclusion and exclusion criteria as well as the NOS quality score. As of May 2022, low intake or low concentration was used as a control, and odds ratio (OR) or relative risk (RR) and ninety-five percent confidence intervals (95% CI) were extracted for high intake. Stata 12.0 was used to process the data.

RESULTS

Our meta-analysis included a total of 49 studies, 29 on breast cancer, 10 on ovarian cancer, and 10 on cervical cancer. There were 38 case-control studies included, with 25,363 cases and 42,281 controls; there were 11 cohort studies included, 1,334,176 individuals were followed up, and finally 9496 obtained cancer. The pooled OR value results were as follows: diet or supplements (OR = 0.83, 95% CI 0.76-0.90, I ² = 56.1%) and serum or plasma (OR = 0.96, 95% CI 0.86-1.09, I ² = 29.5%). Subgroup analyses were performed according to cancer type, diet or supplements, serum or plasma, study type, and geographic regions.

CONCLUSIONS

In North American and Asian populations, high dietary consumption of vitamin A or supplements decreases the incidence of three cancers in women, with breast and ovarian cancers being more significant. However, high circulating vitamin A concentrations were not significantly connected with the risk of the three malignancies.

Association between Micronutrient Intake and Breast Cancer Risk According to Body Mass Index in South Korean Adult Women: A Cohort Study

This study investigated the association between micronutrient intake and breast cancer risk in South Korean adult women. This association was stratified according to body mass index (BMI) categories. Data from the Korean Genome and Epidemiology Study (KoGES) and the Health Examinee Study were analyzed. Altogether, 63,337 individuals (aged ≥40 years) completed the baseline and first follow-up surveys; 40,432 women without a history of cancer at baseline were included in this study. The association between micronutrient intake and breast cancer was determined by estimating the hazard ratio (HR) and 95% confidence interval (CI) using the Cox proportional hazard regression model. A stratified analysis by BMI (<25 kg/m2 and ≥25 kg/m2) was performed. The an analysis of 15 micronutrients and breast cancer risk revealed that none of the micronutrients were associated with breast cancer risk after adjusting for covariates. In obese women, the risk of breast cancer was significantly reduced in the group that consumed vitamin C more than the recommended level (HR = 0.54, 95% CI: 0.31−0.93) and vitamin B6 levels above the recommended level (HR = 0.48, 95% CI: 0.25−0.89). In obese women, exceeding the recommended daily intake levels of vitamin C and vitamin B6 was associated with a lower risk of breast cancer. However, other micronutrients were not associated with breast cancer risk in these women.

The Association Between Vitamin C and Cancer: A Two-Sample Mendelian Randomization Study

In recent years, many studies have indicated that vitamin C might be negatively associated with the risk of cancer, but the actual relationship between vitamin C and cancer remains ambivalent. Therefore, we utilized a two-sample Mendelian randomization (MR) study to explore the causal associations of genetically predicted vitamin C with the risk of a variety of cancers. Single-nucleotide polymorphisms (SNPs) associated with vitamin C at a significance level of p < 5 × 10-8 and with a low level of linkage disequilibrium (LD) (r2 < 0.01) were selected from a genome-wide association study (GWAS) meta-analysis of plasmid concentration of vitamin C consisting of 52,018 individuals. The data of the GWAS outcomes were obtained from United Kingdom Biobank, FinnGen Biobank and the datasets of corresponding consortia. In the inverse-variance weight (IVW) method, our results did not support the causal association of genetically predicted vitamin C with the risk of overall cancer and 14 specific types of cancer. Similar results were observed in sensitivity analyses where the weighted median and MR-Egger methods were adopted, and heterogeneity and pleiotropy were not observed in statistical models. Therefore, our study suggested that vitamin C was not causally associated with the risk of cancer. Further studies are warranted to discover the potential protective and therapeutic effects of vitamin C on cancer, and its underlying mechanisms.

Exploring the Role of Metabolites in Cancer and the Associated Nerve Crosstalk

Since Otto Warburg's first report on the increased uptake of glucose and lactate release by cancer cells, dysregulated metabolism has been acknowledged as a hallmark of cancer that promotes proliferation and metastasis. Over the last century, studies have shown that cancer metabolism is complex, and by-products of glucose and glutamine catabolism induce a cascade of both pro- and antitumorigenic processes. Some vitamins, which have traditionally been praised for preventing and inhibiting the proliferation of cancer cells, have also been proven to cause cancer progression in a dose-dependent manner. Importantly, recent findings have shown that the nervous system is a key player in tumor growth and metastasis via perineural invasion and tumor innervation. However, the link between cancer-nerve crosstalk and tumor metabolism remains unclear. Here, we discuss the roles of relatively underappreciated metabolites in cancer-nerve crosstalk, including lactate, vitamins, and amino acids, and propose the investigation of nutrients in cancer-nerve crosstalk based on their tumorigenicity and neuroregulatory capabilities. Continued research into the metabolic regulation of cancer-nerve crosstalk will provide a more comprehensive understanding of tumor mechanisms and may lead to the identification of potential targets for future cancer therapies.

Vitamin C intake and multiple health outcomes: an umbrella review of systematic reviews and meta-analyses

The purpose of this article was to assess the existing systematic reviews and meta-analyses for the association between vitamin C intake and multiple health outcomes. A total of 76 meta-analyses (51 papers) of randomised controlled trials and observational studies with 63 unique health outcomes were identified. Dose-response analysis showed that vitamin C intake was associated with reduced risk of all-cause mortality, cardiovascular disease (CVD), oesophageal cancer, gastric cancer, cervical cancer and lung cancer with an increment of 50-100 mg per day. Beneficial associations were also identified for respiratory, neurological, ophthalmologic, musculoskeletal, renal and dental outcomes. Harmful associations were found for breast cancer and kidney stones for vitamin C supplement intake. The benefits of vitamin C intake outweigh the disadvantages for a range of health outcomes. However, the recommendation of vitamin C supplements needs to be cautious. More prospective studies and well-designed randomised controlled trials (RCTs) are needed.

Vitamin C and cancer risk and treatment

Vitamin C (L-ascorbic acid) works as a strong reductant, radical scavenger, and protector of cell membranes against primary peroxidative damage in tissues and in the extracellular fluid. L-ascorbic acid is involved in the synthesis of collagen and many other biologically relevant substances, enzyme activity, xenobiotic detoxification, and prevention of forming carcinogenic nitrosamines. It also plays a role in the immune system. Numerous data indicate that cancer patients suffer from vitamin C deficiency. Studies show that people with a low vitamin C intake have an increased risk of head and neck cancers as well as lung, gastric, pancreatic, cervical, rectal, or breast cancer. On the other hand, there is no clinical evidence to support the thesis that antioxidant supplements (including vitamin C) prevent cancer. Observational trials investigating high doses of intravenous L-ascorbic acid in previously treated cancer patients have shown that it allows an increase in quality of life and may improve physical, mental, and emotional functions, as well as reducing adverse effects of standard anticancer treatment, including fatigue, nausea, vomiting, and appetite loss. So far, there were a few randomized controlled trials and they have not reported any statistically significant improvements in the overall or progression-free survival with vitamin C, as compared to the control arm. However, preclinical data indicating a role of L-ascorbic acid in modulation of immune response and its involvement in epigenome remodeling suggest its new potential clinical applications in cancer patients, especially in combination with immunotherapy. It seems reasonable to further investigate the value of vitamin C as a supportive treatment or in combination with anticancer targeted therapy.

The Role of Vitamin C in Cancer Prevention and Therapy: A Literature Review

Vitamin C is a water-soluble antioxidant associated with the prevention of the common cold and is also a cofactor of hydrolases that participate in the synthesis of collagen and catecholamines, and in the regulation of gene expression. In cancer, vitamin C is associated with prevention, progression, and treatment, due to its general properties or its role as a pro-oxidant at high concentration. This review explores the role of vitamin C in cancer clinical trials and the aspects to consider in future studies, such as plasmatic vitamin C and metabolite excretion recording, and metabolism and transport of vitamin C into cancer cells. The reviewed studies show that vitamin C intake from natural sources can prevent the development of pulmonary and breast cancer, and that vitamin C synergizes with gemcitabine and erlotinib in pancreatic cancer. In vitro assays reveal that vitamin C synergizes with DNA-methyl transferase inhibitors. However, vitamin C was not associated with cancer prevention in a Mendelian randomized study. In conclusion, the role of vitamin C in the prevention and treatment of cancer is still an ongoing area of research. It is necessary that new phase II and III clinical trials be performed to collect stronger evidence of the therapeutic role of vitamin C in cancer.

Dietary Vitamin A and Breast Cancer Risk in Black Women: The African American Breast Cancer Epidemiology and Risk (AMBER) Consortium

BACKGROUND

Studies in women of European descent showed an inverse association of dietary vitamin A (retinol and carotenoids) intake with breast cancer risks, mainly in premenopausal women.

OBJECTIVES

We examined whether higher compared with lower levels of dietary vitamin A are associated with reduced breast cancer risks among Black women by estrogen receptor (ER) and menopausal statuses.

METHODS

In this pooled analysis, data were from 3564 breast cancer cases and 11,843 controls (mean ages = 56.4 and 56.3 years, respectively) in the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium. Dietary intake was assessed by FFQs. Multivariable logistic regressions were performed to estimate ORs and 95% CIs for study-specific quintiles of total vitamin A equivalents and individual carotenoids, and a pooled OR was estimated by a random-effect model.

RESULTS

We observed an inverse association of total vitamin A equivalents with ER-positive breast cancer (quintiles 5 compared with 1: pooled OR: 0.82; 95% CI: 0.67-1.00; P-trend = 0.045). The association was seen among premenopausal women (pooled OR: 0.60; 95% CI: 0.43-0.83; P-trend = 0.004), but not among postmenopausal women (pooled OR: 0.99; 95% CI: 0.77-1.28; P-trend = 0.78). Additionally, there were inverse associations of dietary β-carotene (quintiles 5 compared with 1: pooled OR: 0.70; 95% CI: 0.51-0.95; P-trend = 0.08) and lutein (pooled OR: 0.63; 95% CI: 0.45-0.87; P-trend = 0.020) with ER-positive breast cancer among premenopausal women. There was no evidence for an association of total vitamin A equivalents or individual carotenoids with ER-negative breast cancer, regardless of menopausal status.

CONCLUSIONS

Our findings on dietary vitamin A and breast cancer risks in Black women are consistent with observations in women of European descent and advance the literature showing an inverse association for ER-positive disease.

Dietary Antioxidant Vitamins and Minerals and Breast Cancer Risk: Prospective Results from the SUN Cohort

There is growing interest in natural antioxidants and their potential effects on breast cancer (BC). Epidemiological evidence, however, is inconsistent. We prospectively evaluated the association between dietary intake of vitamins A, C, and E, selenium, and zinc and BC among 9983 female participants from the SUN Project, a Mediterranean cohort of university graduates. Participants completed a food frequency questionnaire at baseline, and biennial follow-up information about incident BC diagnosis was collected. Cases were ascertained through revision of medical charts and consultation of the National Death Index. Cox proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CI). During an average follow-up of 11.3 years, 107 incident BC cases were confirmed. The multivariable HRs (95% CI) for BC comparing extreme tertiles of energy-adjusted dietary intakes were 1.07 (0.64–1.77; P_trend = 0.673) for vitamin A, 1.00 (0.58–1.71; P_trend = 0.846) for vitamin C, 0.92 (0.55–1.54; P_trend = 0.728) for vitamin E, 1.37 (0.85–2.20; P_trend = 0.135) for selenium, and 1.01 (0.61–1.69; P_trend = 0.939) for zinc. Stratified analyses showed an inverse association between vitamin E intake and postmenopausal BC (HR_{T3 vs. T1} = 0.35; 95% CI, 0.14–0.86; P_trend = 0.027). Our results did not suggest significant protective associations between dietary vitamins A, C, and E, selenium, or zinc and BC risk.

Association of vitamin C intake with breast cancer risk and mortality: a meta-analysis of observational studies

The association between vitamin C intake and breast cancer is unclear. This meta-analysis aimed to precisely assess the association of vitamin C intake with breast cancer risk and mortality. We searched the PubMed, Embase, and Web of Science databases up to June 2020 and found 69 studies relevant to breast cancer risk (54 studies) and survival (15 studies). Relative risks and 95% confidence intervals were calculated using the random-effects models. Pooled results suggested that the highest versus lowest vitamin C intake was significantly associated with a lower risk of breast cancer incidence (Relative Risk = 0.86; 95% confidence interval, 0.81-0.92). Dietary vitamin C but not supplements was found to reduce breast cancer risk (Relative Risk = 0.89; 95% confidence interval, 0.82-0.96). For the highest versus lowest vitamin C intake, the pooled hazard risk for breast cancer-specific mortality was 0.78 (95% confidence interval, 0.69-0.88), totality mortality was 0.82 (95% confidence interval, 0.74-0.91), and recurrence was 0.81 (95% confidence interval, 0.67-0.99). Our analysis suggests that higher vitamin C intake is significantly associated with reduced breast cancer incidence and mortality. However, the intake of vitamin C supplements has no significant effect on breast cancer prevention.

Vitamins and Uterine Fibroids: Current Data on Pathophysiology and Possible Clinical Relevance

Uterine fibroid (UF) is the most common benign tumor pathology of the female reproductive organs. UFs constitute the main reason for a hysterectomy and hospitalization due to gynecological conditions. UFs consist of uterine smooth muscle immersed in a large amount of extracellular matrix (ECM). Genetic studies have demonstrated that UFs are monoclonal tumors originating from the myometrial stem cells that have underwent specific molecular changes to tumor initiating stem cells which proliferate and differentiate later under the influence of steroid hormones. There is growing interest in the role of micronutrients, for example, vitamins, in UFs. This article is a comprehensive review of publications regarding the available data concerning the role of vitamins in the biology and management of UFs. In summary, the results showed that some vitamins are important in the biology and pathophysiology of UFs. For example, vitamins A and D deserve particular attention following studies of their influence on the treatment of UF tumors. Vitamins B3, C, and E have not been as widely studied as the abovementioned vitamins. However, more research could reveal their potential role in UF biology.

Pro- and Antioxidant Effects of Vitamin C in Cancer in correspondence to Its Dietary and Pharmacological Concentrations

Vitamin C is an antioxidant that may scavenge reactive oxygen species preventing DNA damage and other effects important in cancer transformation. Dietary vitamin C from natural sources is taken with other compounds affecting its bioavailability and biological effects. High pharmacological doses of vitamin C may induce prooxidant effects, detrimental for cancer cells. An oxidized form of vitamin C, dehydroascorbate, is transported through glucose transporters, and cancer cells switch from oxidative phosphorylation to glycolysis in energy production so an excess of vitamin C may limit glucose transport and ATP production resulting in energetic crisis and cell death. Vitamin C may change the metabolomic and epigenetic profiles of cancer cells, and activation of ten-eleven translocation (TET) proteins and downregulation of pluripotency factors by the vitamin may eradicate cancer stem cells. Metastasis, the main reason of cancer-related deaths, requires breakage of anatomical barriers containing collagen, whose synthesis is promoted by vitamin C. Vitamin C induces degradation of hypoxia-inducible factor, HIF-1, essential for the survival of tumor cells in hypoxic conditions. Dietary vitamin C may stimulate the immune system through activation of NK and T cells and monocytes. Pharmacological doses of vitamin C may inhibit cancer transformation in several pathways, but further studies are needed to address both mechanistic and clinical aspects of this effect.

Vitamin E consumption and the risk of bladder cancer

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Vitamin A and Breast Cancer Survival: A Systematic Review and Meta-analysis

BACKGROUND

The association between vitamin A intake and breast cancer survival has been inconsistent. We conducted a systemic review and meta-analysis to summarize the results on the association between dietary or supplement vitamin A and its derivatives and breast cancer-specific survival and overall survival (OS). MATERIALS AND METHODS: A comprehensive search of PubMed and EMBASE was performed from inception to January 31, 2018. The summary hazard ratios and 95% confidence intervals were estimated using a random effects model.

RESULTS

Ten studies (8 cohort, 1 clinical trial, and 1 of pooled studies), with 19,450 breast cancer cases, were included in the meta-analysis. The dietary intake of β-carotene was significantly associated with improved breast cancer OS, with a summary hazard ratio of 0.70 (95% confidence interval, 0.50-0.99; I² = 37.5%) for the highest versus lowest intake and 0.93 (95% confidence interval, 0.88-0.99; I² = 38.7%) per 1200 μg/day increment of intake when assessing diet before diagnosis. Meta-regression analysis showed that adjustment for body mass index was a modified factor for the association between the intake of β-carotene and breast cancer OS (P = .013). However, the intake of other vitamin A derivatives (eg, α-carotene, β-cryptoxanthin, lycopene, retinol, lutein) had no effect on breast cancer prognosis when assessing diet before and after the diagnosis.

CONCLUSION

Our findings suggest limited evidence for the significantly inverse association between the prediagnosis dietary intake of β-carotene and OS among women with breast cancer. However, the intake of other vitamin A derivatives was not significantly associated with survival.

A systematic review and meta-analysis of the association between vitamin A intake, serum vitamin A, and risk of liver cancer

BACKGROUND

Previous evidence supports that vitamin A decreases the risk of several types of cancer. However, the association between vitamin A and liver cancer is inconclusive.

AIM

This systematic review and meta-analysis summarizes the existing literature, discussing the association between vitamin A intake, serum vitamin A, and liver cancer in adult populations.

METHODS

A systematic literature review was performed by searching the EMBASE, PubMed, Scopus and International Pharmaceutical Abstract databases using terms related to vitamin A (e.g. retinol, α-carotene, β-carotene, and β-cryptoxanthin) and hepatic cancer without applying any time restriction. A meta-analysis was performed using random effect models.

RESULTS

The meta-analysis of five studies showed no association between serum retinol and liver cancer (pooled risk ratio = 1.90 (0.40-9.02); n = 5 studies, I² = 92%). In addition, the systematic review of studies from 1955 to July 2017 found studies that indicated no association between the intake and serum level of α-carotene ( n = 2) and β-cryptoxanthin ( n = 1) and the risk of liver cancer. Further, the associations between retinol intake ( n = 3), β-carotene intake ( n = 3), or serum β-carotene ( n = 3) and liver cancer were inconclusive.

CONCLUSIONS

Current information on the association between vitamin A intake and liver cancer or serum vitamin A and liver cancer are limited. Most studies demonstrated no association between dietary vitamin A and the risk of liver cancer. However, the finding was based on a small number of studies with potential publication bias. Therefore, large observational studies should be conducted to confirm these associations.

α-Tocopherol succinate enhances pterostilbene anti-tumor activity in human breast cancer cells in vivo and in vitro

Vitamin E (Vit. E) is considered an essential dietary nutrient for humans and animals. An enormous body of evidence indicates the biological and protective effects of Vit. E consumption. Tocopherol-associated protein (TAP) is a major tocopherol-binding protein affecting Vit. E stimulation and downstream signaling transduction. However, how Vit. E utilizes TAP as an anti-cancer mechanism remains unclear. Microarray analysis of signature gene profiles in breast cancer cells treated with α-tocopheryl succinate (α-TOS, a Vit. E isoform) resulted in cell cycle arrest and anti-cancer activity in breast cancer cells. Pterostilbene (PS), a natural dietary antioxidant found in blueberries, in combination with α-TOS synergistically maximized breast cancer cell growth inhibition by disrupting signal transduction, transcription factors and cell cycle proteins. In a xenograft mouse model, PS treatment with Vit. E inhibited breast tumor growth and cell invasion, which were evaluated using our recently developed circulating tumor cell (CTC) detection assay. Because dietary Vit. E and PS supplementation contributed to preventative and therapeutic effects in vitro and in vivo, this combination may benefit breast cancer therapy in the clinic.

Nature, Nurture, and Cancer Risks: Genetic and Nutritional Contributions to Cancer

It is speculated that genetic variants are associated with differential responses to nutrients (known as gene-diet interactions) and that these variations may be linked to different cancer risks. In this review, we critically evaluate the evidence across 314 meta-analyses of observational studies and randomized controlled trials of dietary risk factors and the five most common cancers (breast, lung, prostate, colorectal, and stomach). We also critically evaluate the evidence across 13 meta-analyses of observational studies of gene-diet interactions for the same cancers. Convincing evidence for association was found only for the intake of alcohol and whole grains in relation to colorectal cancer risk. Three nutrient associations had highly suggestive evidence and another 15 associations had suggestive evidence. Among the examined gene-diet interactions, only one had moderately strong evidence.

Vitamins, Are They Safe?

The consumption of a daily multivitamin among people all over the world is dramatically increasing in recent years. Most of the people believe that if vitamins are not effective, at least they are safe. However, the long term health consequences of vitamins consumption are unknown. This study aimed to assess the side effects and possible harmful and detrimental properties of vitamins and to discuss whether vitamins can be used as safe health products or dietary supplements. We performed a MEDLINE/PubMed, EMBASE, Scopus and Google Scholar search and assessed reference lists of the included studies which were published from 1993 through 2015. The studies, with an emphasis on RCTs (randomized controlled clinical trials), were reviewed. As some vitamins such as fat-soluble vitamins (vitamin A, vitamin D, vitamin E), and also some of the water-soluble vitamins like folic acid may cause adverse events and some like vitamin C is widely taken assuming that it has so many benefits and no harm, we included relevant studies with negative or undesired results regarding the effect of these vitamins on health. Our recommendation is that taking high-dose supplements of vitamins A, E, D, C, and folic acid is not always effective for prevention of disease, and it can even be harmful to the health.

Association between vitamin A, retinol and carotenoid intake and pancreatic cancer risk: Evidence from epidemiologic studies

Pancreatic cancer is a devastating disease with poor prognosis. The association between vitamin A, retinol and carotenoid intake and the risk of pancreatic cancer occurrence remains controversial, and therefore it is necessary to make a meta-analysis to clarify the association between vitamin A, retinol and carotenoid intake and pancreatic cancer risk. In the present study, PubMed and EMBASE databases were used to identify qualified studies. The association between dietary vitamin A, retinol and carotenoids was estimated by pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs). It was found that there was an inverse correlation between vitamin A, beta-carotene and lycopene intake and the risk of pancreatic cancer (for vitamin A, pooled OR = 0.85, 95%CI = 0.74–0.97, P = 0.015; for beta-carotene, pooled OR = 0.78, 95%CI = 0.66–0.92, P = 0.003; for lycopene, pooled OR = 0.84, 95%CI = 0.73–0.97, P = 0.020), which was more prominent in case-control study subgroup. In conclusion, dietary vitamin A, beta-carotene and lycopene might inversely correlate with pancreatic cancer.

Evaluation of Antioxidant Intakes in Relation to Inflammatory Markers Expression Within the Normal Breast Tissue of Breast Cancer Patients

Chronic inflammation may be a causative factor in breast cancer. One possible underlying mechanism is the generation of oxidative stress, which may favor tumorigenic processes. Antioxidant consumption may, therefore, help reduce tissue inflammation levels. However, few studies have explored this relation in breast tissue. We aimed to evaluate correlations between antioxidant (vitamin A/retinol, vitamin C, vitamin E, β-carotene, α-carotene, lycopene, lutein/zeaxanthin, β-cryptoxanthin, selenium, and zinc) intakes and protein expression levels of interleukin (IL)-6, tumor necrosis factor-α, C-reactive protein, cyclooxygenase-2, leptin, serum amyloid A1, signal transducer and activator of transcription 3, IL-8, IL-10, lactoferrin, and transforming growth factor-β measured in the normal breast tissue of 160 women diagnosed with breast cancer. Antioxidant intakes were collected using a self-administered food frequency questionnaire. Inflammation marker expression was assessed by immunohistochemistry. Correlations between antioxidant intakes and inflammatory marker expression were evaluated using Spearman's partial correlation coefficients ( r) for all women and for premenopausal and postmenopausal women separately. After Bonferroni correction, negative correlations were observed between dietary β-tocopherol and IL-10 expression in all women combined ( r = -0.26, P = .003) and among postmenopausal women ( r = -0.39, P = .003). For all women, a negative correlation was found between total zinc intakes and IL-10 ( r = -0.26, P = .002). Among postmenopausal women, dietary selenium intake was negatively correlated with the expression of lactoferrin ( r = -0.39, P = .003). No associations were observed in premenopausal women. Our findings suggest that consumption of specific antioxidants, including β-tocopherol, zinc, and selenium, may act on the breast tissue through mechanisms affecting the expression of some inflammation markers, particularly among postmenopausal women.

Biomarkers of Nutrition for Development (BOND)-Vitamin A Review

The Biomarkers of Nutrition for Development (BOND) project is designed to provide evidence-informed advice to anyone with an interest in the role of nutrition in health. The BOND program provides information with regard to selection, use, and interpretation of biomarkers of nutrient exposure, status, function, and effect, which will be especially useful for readers who want to assess nutrient status. To accomplish this objective, expert panels are recruited to evaluate the literature and to draft comprehensive reports on the current state of the art with regard to specific nutrient biology and available biomarkers for assessing nutritional status at the individual and population levels. Phase I of the BOND project includes the evaluation of biomarkers for 6 nutrients: iodine, folate, zinc, iron, vitamin A, and vitamin B-12. This review of vitamin A is the current article in this series. Although the vitamin was discovered >100 y ago, vitamin A status assessment is not trivial. Serum retinol concentrations are under homeostatic control due in part to vitamin A's use in the body for growth and cellular differentiation and because of its toxic properties at high concentrations. Furthermore, serum retinol concentrations are depressed during infection and inflammation because retinol-binding protein (RBP) is a negative acute-phase reactant, which makes status assessment challenging. Thus, this review describes the clinical and functional indicators related to eye health and biochemical biomarkers of vitamin A status (i.e., serum retinol, RBP, breast-milk retinol, dose-response tests, isotope dilution methodology, and serum retinyl esters). These biomarkers are then related to liver vitamin A concentrations, which are usually considered the gold standard for vitamin A status. With regard to biomarkers, future research questions and gaps in our current understanding as well as limitations of the methods are described.

Vitamin C supplement intake and postmenopausal breast cancer risk: interaction with dietary vitamin C

BACKGROUND

Experimental and epidemiologic studies have yielded conflicting results on the relation between vitamin C intake and breast cancer risk.

OBJECTIVE

We investigated the relation between vitamin C supplement intake and breast cancer risk while considering dietary vitamin C intake.

DESIGN

Between 1995 and 2008, 2482 invasive breast cancer cases occurred in 57,403 postmenopausal women from the Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l'Education Nationale (E3N) prospective cohort during 581,085 person-years. We estimated vitamin C intake from foods with the use of a validated food-frequency questionnaire that was sent to subjects in 1993-1995 and vitamin C supplement use via questionnaires sent in 1995, 2000, 2002, and 2005. Multivariable HRs (95% CIs) for primary invasive breast cancer were estimated with the use of Cox regression models. All statistical tests were 2-sided.

RESULTS

Vitamin C supplement use (ever compared with never) was not associated with breast cancer risk overall; it was associated with higher breast cancer risk in women in the fourth quartile of vitamin C intake from foods (HR: 1.32; 95% CI: 1.04, 1.67) but not in other quartiles of dietary vitamin C intake (P-interaction = 0.03).

CONCLUSIONS

We observed that vitamin C supplement use was associated with increased postmenopausal breast cancer risk in women with high vitamin C intake from foods. Our data suggest a potential U- or J-shaped relation between total vitamin C intake and postmenopausal breast cancer risk that deserves further investigation.

Oral health status: relationship to nutrient and food intake among 80-year-old Japanese adults

OBJECTIVES

The aim of this cross-sectional study was to investigate the relationship of oral health status defined on the basis of presence of posterior occluding pairs (POPs) and adequacy of removable denture fit as determined by self-report to nutrient and food intake among older Japanese.

METHODS

The subjects were 353 Japanese aged 80 years in 2008 and were classified into four groups according to the number of POPs, defined as pairs of occluding natural, restored, or fixed prosthetic postcanine teeth (range: 0-8) and removable denture status. The groups were: (i) good dentition (n = 56; 8 POPs and no removable prosthesis), (ii) well-fitting dentures (n = 158; <8 POPs with self-reported good-fitting dentures), (iii) ill-fitting dentures (n = 70; <8 POPs with self-reported ill-fitting dentures), and (iv) compromised dentition (n = 69; <8 POPs and no removable prosthesis). Multivariable analysis of the differences in nutrient and food intake outcome variables which were collected via validated food frequency questionnaire among the four oral health status groups was conducted using general linear models. Results: Intake of multiple nutrients was significantly (P < 0.05) lower in the group with ill-fitting dentures or compromised dentition than in the good dentition group. Vegetable, fish, and shellfish consumption was significantly lower in the ill-fitting dentures or compromised dentition groups. No significant differences were seen in dietary intake between the well-fitting dentures and good dentition groups. Conclusions: Dietary intake was poorer in those with self-perceived ill-fitting dentures or fewer POPs than among those having all POPs. Regular dental care to maintain intact dentition, as well as dental treatment to replace missing teeth and ensure adequate denture fit and function, may be important to the diet intake and subsequent nutritional status of older Japanese.

Intakes of fat and micronutrients between ages 13 and 18 years and the incidence of proliferative benign breast disease

PURPOSE

Dietary exposures during adolescence may exert important effects on breast development and future breast cancer risk. This study evaluated the associations between high school intakes of fat and micronutrients and the incidence of proliferative benign breast disease (BBD), a marker of increased breast cancer risk.

METHODS

29,480 women (mean age 43.3 years, range 33.6-52.9) completed a high school food frequency questionnaire in 1998 in the Nurses' Health Study II. Between 1991 and 2001, 682 women (follow-up time: 259,828 person-years) were diagnosed with proliferative BBD whose biopsy slides were reviewed and confirmed by the study pathologists.

RESULTS

In multivariate Cox proportional hazards models, high school intakes of total fat and types of fat were not associated with proliferative BBD. Women in the highest quintile of total retinol activity equivalents (RAEs), which incorporate retinol, α- and β-carotene, and β-cryptoxanthin intakes, had a 17 % lower risk of proliferative BBD than those in the lowest quintile [multivariate hazard ratio (HR) 95 % CI 0.83 (0.64, 1.07), p trend = 0.01]; however, additional adjustment for high school dietary factors (vitamin D, nuts, and fiber) rendered the association nonsignificant [0.99 (0.73, 1.34), p trend = 0.32]. Results were similar with additional adjustment for adult RAE intake. Intakes of vitamin E and individual carotenoids were not associated with proliferative BBD, although an inverse association cannot be ruled out.

CONCLUSIONS

In this study, adolescent fat and micronutrient intakes were not associated with risk of proliferative BBD.

The plasma level of retinol, vitamins A, C and α-tocopherol could reduce breast cancer risk? A meta-analysis and meta-regression

PURPOSE

Plasma antioxidants are supposed to be directly related to breast cancer risk. However, the results remain inconsistent. Herein, we carried this meta-analysis to comprehensively summarize the associations between plasma retinol, vitamins A, C and α-tocopherol and breast cancer risk.

METHODS

We searched PubMed, Embase and the Cochrane Databases (through September 24, 2014) and the reference lists of the retrieved articles in English with sufficient information to estimate relative risk or odds ratio and the 95% confidence intervals (CIs), or with mean serum/plasma level of vitamins and SD/SEM/p value in breast cancer and controls. Two reviewers independently extracted data using a standardized form, with any discrepancy adjudicated by the third reviewer.

RESULTS

Forty studies entered this meta-analysis. For the pooled OR, no significant association between plasma retinol and breast cancer was observed (p = 0.13). Significant association was observed between plasma α-tocopherol and breast cancer (pooled OR 0.42, 95% CI 0.25, 0.72, p = 0.00) in the subgroup with the median lowest level of 5.74-9.16 μmol/L. For the weighted mean difference (WMD), the plasma α-tocopherol and vitamin C level between breast cancer and controls were significantly different [WMD = -0.93 μmol/L (95% CI -1.26, -0.61, p = 0.00) and -2.51 μmol/L (95% CI -4.00, -1.02, p = 0.00), respectively]. No significant association between plasma retinol and vitamin A and breast cancer was observed.

CONCLUSIONS

Severe α-tocopherol deficiency could increase breast cancer risk. The association between plasma vitamin C and breast cancer was only significant in case-control studies. There was no significant association between other vitamins and breast cancer risk.

Association between vitamin C intake and lung cancer: a dose-response meta-analysis

Epidemiological studies evaluating the association between the intake of vitamin C and lung cancer risk have produced inconsistent results. We conducted a meta-analysis to assess the association between them. Pertinent studies were identified by a search of PubMed, Web of Knowledge and Wan Fang Med Online through December of 2013. Random-effect model was used to combine the data for analysis. Publication bias was estimated using Begg's funnel plot and Egger's regression asymmetry test. Eighteen articles reporting 21 studies involving 8938 lung cancer cases were included in this meta-analysis. Pooled results suggested that highest vitamin C intake level versus lowest level was significantly associated with the risk of lung cancer [summary relative risk (RR) = 0.829, 95%CI = 0.734–0.937, I² = 57.8%], especially in the United States and in prospective studies. A linear dose-response relationship was found, with the risk of lung cancer decreasing by 7% for every 100 mg/day increase in the intake of vitamin C [summary RR = 0.93, 95%CI = 0.88–0.98]. No publication bias was found. Our analysis suggested that the higher intake of vitamin C might have a protective effect against lung cancer, especially in the United States, although this conclusion needs to be confirmed.

A systematic review and meta-analysis on the prevalence of dietary supplement use by military personnel

Background

Although a number of studies have been conducted on the prevalence of dietary supplement (DS) use in military personnel, these investigations have not been previously summarized. This article provides a systematic literature review of this topic.

Methods

Literature databases, reference lists, and other sources were searched to find studies that quantitatively examined the prevalence of DS use in uniformed military groups. Prevalence data were summarized by gender and military service. Where there were at least two investigations, meta-analysis was performed using a random model and homogeneity of the prevalence values was assessed.

Results

The prevalence of any DS use for Army, Navy, Air Force, and Marine Corps men was 55%, 60%, 60%, and 61%, respectively; for women corresponding values were 65%, 71%, 76%, and 71%, respectively. Prevalence of multivitamin and/or multimineral (MVM) use for Army, Navy, Air Force, and Marine Corps men was 32%, 46%, 47%, and 41%, respectively; for women corresponding values were 40%, 55%, 63%, and 53%, respectively. Use prevalence of any individual vitamin or mineral supplement for Army, Navy, Air Force, and Marine Corps men was 18%, 27%, 25%, and 24%, respectively; for women corresponding values were 29%, 36%, 40%, and 33%, respectively. Men in elite military groups (Navy Special Operations, Army Rangers, and Army Special Forces) had a use prevalence of 76% for any DS and 37% for MVM, although individual studies were not homogenous. Among Army men, Army women, and elite military men, use prevalence of Vitamin C was 15% for all three groups; for Vitamin E, use prevalence was 8%, 7%, and 9%, respectively; for sport drinks, use prevalence was 22%, 25% and 39%, respectively. Use prevalence of herbal supplements was generally low compared to vitamins, minerals, and sport drinks, ≤5% in most investigations.

Conclusions

Compared to men, military women had a higher use prevalence of any DS and MVM. Army men and women tended to use DSs and MVM less than other service members. Elite military men appeared to use DSs and sport drinks more than other service members.

Avaliação nutricional de pacientes com câncer de mama atendidas no Serviço de Mastologia do Hospital das Clínicas, Belo Horizonte (MG), Brasil

O objetivo deste artigo é avaliar o perfil nutricional, a composição corporal e as características tumorais de 31 pacientes com câncer de mama atendidas pelo Serviço de Mastologia do Hospital das Clínicas da Universidade Federal de Minas Gerais. Os dados da dieta foram coletados usando-se o recordatório de 24 horas no momento pré-cirúrgico e analisados pelo Software de Nutrição DietWin Profissional 2008. A composição corporal foi avaliada por análise de impedância bioelétrica. A caracterização tumoral foi realizada através da avaliação dos dados obtidos no prontuário de cada paciente. A idade média foi de 50,75 ± 14,3 anos. Foi observado excesso de peso corporal em 58% das pacientes e circunferência da cintura maior que 80 cm em 64,5%. Consumo excessivo de alimentos pertencentes aos grupos dos óleos e dos açúcares foi verificado em 90,3% e 83,8%, respectivamente. A maioria das pacientes apresentou baixo consumo de cálcio e de vitaminas B6, B12 e A. O diagnóstico predominante foi de carcinoma ductal invasivo, de grau histológico tipo II em estadio II ou III. A prevalência do excesso de peso e a inadequação do consumo alimentar demonstram a necessidade de orientação e acompanhamento nutricional individualizado, visando melhorar o prognóstico e a qualidade de vida da paciente.

Plasma micronutrients, trace elements, and breast cancer in BRCA1 mutation carriers: an exploratory study

PURPOSE

Few studies have evaluated the role of micronutrients or trace elements in breast cancer development among BRCA1 mutation carriers. To investigate a possible role of dietary and environmental exposures on cancer risk, we undertook an exploratory study, using a matched case-control design (n = 48 cases and 96 controls), to evaluate the relationships between plasma levels of 14 micronutrients and breast cancer risk among BRCA1 mutation carriers in Poland.

METHODS

We estimated the univariate odds ratios (OR) and 95 % confidence intervals (CI) for breast cancer associated with plasma levels for each of 14 micronutrients.

RESULTS

Of the 14 analytes quantified, significant differences between cases and controls were seen for two (iron and retinol; p = 0.009 and p = 0.03, respectively). Women in the highest tertile of plasma iron had a 57 % lower risk, compared with those in the lowest quartile (OR = 0.43; 95 % CI 0.18-1.04; p for trend = 0.06). Increasing antimony levels were associated with an increased risk of breast cancer (p for trend = 0.05). Women in the highest tertile had a 2.43-fold increase in breast cancer risk compared with women in the lowest tertile (OR = 2.43; 95 % CI 1.00-5.91).

CONCLUSIONS

This study provides some preliminary evidence regarding a role of diet, specifically iron and antimony, in the etiology of BRCA1-associated breast cancer. Prospective studies are necessary to confirm these findings.

Cancer prevention by different forms of tocopherols

Many epidemiological studies have suggested that a low vitamin E nutritional status is associated with increased cancer risk. However, several recent large-scale human trials with high doses of α-tocopherol (α-T) have produced disappointing results. This points out the need for a better understanding of the biological activities of the different forms of tocopherols. Using a naturally occurring tocopherol mixture (γ-TmT) that is rich in γ-T, we demonstrated the inhibition of chemically induced lung, colon, and mammary cancer formation as well as the growth of xenograft tumors derived from human lung and prostate cancer cells. This broad anticancer activity of γ-TmT has been attributed mainly to the trapping of reactive oxygen and nitrogen species and inhibition of arachidonic acid metabolism. Activation of peroxisome proliferator-activated receptor γ (PPARγ) and the inhibition of estrogen signaling have also been observed in the inhibition of mammary cancer development. δ-T has been shown to be more active than γ-T in inhibiting the growth of human lung cancer cells in a xenograft tumor model and the development of aberrant crypt foci in azoxymethane-treated rats, whereas α-T is not effective in these models. The higher inhibitory activities of δ-T and γ-T (than α-T) are proposed to be due to their trapping of reactive nitrogen species and their capacity to generate side-chain degradation products, which retain the intact chromanol ring structure and could have cancer preventive activities.

Chemopreventive activity of vitamin E in breast cancer: a focus on γ- and δ-tocopherol

Vitamin E consists of eight different variants: α-, β-, γ-, and δ-tocopherols (saturated phytyl tail) and α-, β-, γ-, and δ-tocotrienols (unsaturated phytyl tail). Cancer prevention studies with vitamin E have primarily utilized the variant α-tocopherol. To no avail, a majority of these studies focused on variant α-tocopherol with inconsistent results. However, γ-tocopherol, and more recently δ-tocopherol, have shown greater ability to reduce inflammation, cell proliferation, and tumor burden. Recent results have shown that γ-enriched mixed tocopherols inhibit the development of mammary hyperplasia and tumorigenesis in animal models. In this review, we discuss the possible differences between the variant forms, molecular targets, and cancer-preventive effects of tocopherols. We recommend that a γ-enriched mixture, γ- and δ-tocopherol, but not α-tocopherol, are promising agents for breast cancer prevention and warrant further investigation.