Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies

Evaluating agreement between evidence from randomised controlled trials and cohort studies in nutrition: a meta-research replication study

This meta-research study aims to evaluate the agreement of effect estimates between bodies of evidence (BoE) from RCTs and cohort studies included in the same nutrition evidence synthesis, to identify factors associated with disagreement, and to replicate the findings of a previous study. We searched Medline, Epistemonikos and the Cochrane Database of Systematic Reviews for nutrition systematic reviews that included both RCTs and cohort studies for the same patient-relevant outcome or intermediate-disease marker. We rated similarity of PI/ECO (population, intervention/exposure, comparison, outcome) between BoE from RCTs and cohort studies. Agreement of effect estimates across BoE was analysed by pooling ratio of risk ratios (RRR) for binary outcomes and difference of standardised mean differences (DSMD) for continuous outcomes. We performed subgroup and sensitivity analyses to explore determinants associated with disagreements. We included 82 BoE-pairs from 51 systematic reviews. For binary outcomes, the RRR was 1.04 (95% confidence interval (CI) 0.99 to 1.10, I2 = 59%, τ2 = 0.02, prediction interval (PI) 0.77 to 1.41). For continuous outcomes, the pooled DSMD was  - 0.09 (95% CI  - 0.26 to 0.09, PI  - 0.55 to 0.38). Subgroup analyses yielded that differences in type of intake/exposure were drivers towards disagreement. We replicated the findings of a previous study, where on average RCTs and cohort studies had similar effect estimates. Disagreement and wide prediction intervals were mainly driven by PI/ECO-dissimilarities. More research is needed to explore other potentially influencing factors (e.g. risk of bias) on the disagreement between effect estimates of both BoE.Trial registration: CRD42021278908.

Risk Factors for Ovarian Cancer: An Umbrella Review of the Literature

Several non-genetic factors have been associated with ovarian cancer incidence or mortality. To evaluate the strength and validity of the evidence we conducted an umbrella review of the literature that included systematic reviews/meta-analyses that evaluated the link between non-genetic risk factors and ovarian cancer incidence and mortality. We searched PubMed, EMBASE, Cochrane Database of Systematic Reviews and performed a manual screening of references. Evidence was graded into strong, highly suggestive, suggestive or weak based on statistical significance of the random effects summary estimate and the largest study in a meta-analysis, the number of cases, between-study heterogeneity, 95% prediction intervals, small study effects, and presence of excess significance bias. We identified 212 meta-analyses, investigating 55 non-genetic risk factors for ovarian cancer. Risk factors were grouped in eight broad categories: anthropometric indices, dietary intake, physical activity, pre-existing medical conditions, past drug history, biochemical markers, past gynaecological history and smoking. Of the 174 meta-analyses of cohort studies assessing 44 factors, six associations were graded with strong evidence. Greater height (RR per 10 cm 1.16, 95% confidence interval (CI) 1.11-1.20), body mass index (BMI) (RR ≥ 30 kg/m2 versus normal 1.27, 95% CI 1.17-1.38) and three exposures of varying preparations and usage related to hormone replacement therapy (HRT) use increased the risk of developing ovarian cancer. Use of oral contraceptive pill reduced the risk (RR 0.74, 95% CI 0.69-0.80). Refining the significance of genuine risk factors for the development of ovarian cancer may potentially increase awareness in women at risk, aid prevention and early detection.

Evaluating Concordance of Bodies of Evidence from Randomized Controlled Trials, Dietary Intake, and Biomarkers of Intake in Cohort Studies: A Meta-Epidemiological Study

We aimed to identify and compare empirical data to determine the concordance of diet-disease effect estimates of bodies of evidence (BoE) from randomized controlled trials (RCTs), dietary intake, and biomarkers of dietary intake in cohort studies (CSs). The Cochrane Database of Systematic Reviews and MEDLINE were searched for systematic reviews (SRs) of RCTs and SRs of CSs that investigated both dietary intake and biomarkers of intake published between 1 January 2010 and 31 December 2019. For matched diet-disease associations, the concordance between results from the 3 different BoE was analyzed using 2 definitions: qualitative (e.g., 95% CI within a predefined range) and quantitative (test hypothesis on the z score). Moreover, the differences in the results coming from BoERCTs, BoECSs dietary intake, and BoECSs biomarkers were synthesized to get a pooled ratio of risk ratio (RRR) across all eligible diet-disease associations, so as to compare the 3 BoE. Overall, 49 diet-disease associations derived from 41 SRs were identified and included in the analysis. Twenty-four percent, 10%, and 39% of the diet-disease associations were qualitatively concordant comparing BoERCTs with BoECSs dietary intake, BoERCTs with BoECSs biomarkers, and comparing both BoE from CSs, respectively; 88%, 69%, and 90% of the diet-disease associations were quantitatively concordant comparing BoERCTs with BoECSs dietary intake, BoERCTs with BoECSs biomarkers, and comparing both BoE from CSs, respectively. The pooled RRRs comparing effects from BoERCTs with effects from BoECSs dietary intake were 1.09 (95% CI: 1.06, 1.13) and 1.18 (95% CI: 1.10, 1.25) compared with BoECSs biomarkers. Comparing both BoE from CSs, the difference in the results was also small (RRR: 0.92; 95% CI: 0.88, 0.96). Our findings suggest that BoE from RCTs and CSs are often quantitatively concordant. Prospective SRs in nutrition research should include, whenever possible, BoE from RCTs and CSs on dietary intake and biomarkers of intake to provide the whole picture for an investigated diet-disease association.

Evaluating agreement between bodies of evidence from randomised controlled trials and cohort studies in nutrition research: meta-epidemiological study

OBJECTIVE

To evaluate the agreement between diet-disease effect estimates of bodies of evidence from randomised controlled trials and those from cohort studies in nutrition research, and to investigate potential factors for disagreement.

DESIGN

Meta-epidemiological study.

DATA SOURCES

Cochrane Database of Systematic Reviews, and Medline.

REVIEW METHODS

Population, intervention or exposure, comparator, outcome (PI/ECO) elements from a body of evidence from cohort studies (BoE(CS)) were matched with corresponding elements of a body of evidence from randomised controlled trials (BoE(RCT)). Pooled ratio of risk ratios or difference of mean differences across all diet-disease outcome pairs were calculated. Subgroup analyses were conducted to explore factors for disagreement. Heterogeneity was assessed through I2 and τ2. Prediction intervals were calculated to assess the range of possible values for the difference in the results between evidence from randomised controlled trials and evidence from cohort studies in future comparisons.

RESULTS

97 diet-disease outcome pairs (that is, matched BoE(RCT) and BoE(CS)) were identified overall. For binary outcomes, the pooled ratio of risk ratios comparing estimates from BoE(RCT) with BoE(CS) was 1.09 (95% confidence interval 1.04 to 1.14; I2=68%; τ2=0.021; 95% prediction interval 0.81 to 1.46). The prediction interval indicated that the difference could be much more substantial, in either direction. We further explored heterogeneity and found that PI/ECO dissimilarities, especially for the comparisons of dietary supplements in randomised controlled trials and nutrient status in cohort studies, explained most of the differences. When the type of intake or exposure between both types of evidence was identical, the estimates were similar. For continuous outcomes, small differences were observed between randomised controlled trials and cohort studies.

CONCLUSION

On average, the difference in pooled results between estimates from BoE(RCT) and BoE(CS) was small. But wide prediction intervals and some substantial statistical heterogeneity in cohort studies indicate that important differences or potential bias in individual comparisons or studies cannot be excluded. Observed differences were mainly driven by dissimilarities in population, intervention or exposure, comparator, and outcome. These findings could help researchers further understand the integration of such evidence into prospective nutrition evidence syntheses and improve evidence based dietary guidelines.

Improving the trustworthiness of findings from nutrition evidence syntheses: assessing risk of bias and rating the certainty of evidence

Suboptimal diet is recognized as a leading modifiable risk factor for non-communicable diseases. Non-randomized studies (NRSs) with patient relevant outcomes provide many insights into diet-disease relationships. Dietary guidelines are based predominantly on findings from systematic reviews of NRSs-mostly prospective observational studies, despite that these have been repeatedly criticized for yielding potentially less trustworthy results than randomized controlled trials (RCTs). It is assumed that these are a result of bias due to prevalent-user designs, inappropriate comparators, residual confounding, and measurement error. In this article, we aim to highlight the importance of applying risk of bias (RoB) assessments in nutritional studies to improve the credibility of evidence of systematic reviews. First, we discuss the importance and challenges of dietary RCTs and NRSs, and provide reasons for potentially less trustworthy results of dietary studies. We describe currently used tools for RoB assessment (Cochrane RoB, and ROBINS-I), describe the importance of rigorous RoB assessment in dietary studies and provide examples that further the understanding of the key issues to overcome in nutrition research. We then illustrate, by comparing the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach with current approaches used by United States Department of Agriculture Dietary Guidelines for Americans, and the World Cancer Research Fund, how to establish trust in dietary recommendations. Our overview shows that the GRADE approach provides more transparency about the single domains for grading the certainty of the evidence and the strength of recommendations. Despite not increasing the certainty of evidence itself, we expect that the rigorous application of the Cochrane RoB and the ROBINS-I tools within systematic reviews of both RCTs and NRSs and their integration within the GRADE approach will strengthen the credibility of dietary recommendations.

The Sorbus spp.-Underutilised Plants for Foods and Nutraceuticals: Review on Polyphenolic Phytochemicals and Antioxidant Potential

The Sorbus spp. are valuable plants, which have been used for ornamental purposes, in traditional medicines and less seldom in foods. Recent studies have revealed different anatomical parts of the Sorbus spp. to contain valuable phytochemicals demonstrating various bioactivities. However, in terms of applications in the products intended for human consumption, Sorbus still remains as an underutilised genus. The increasing number of studies on phytochemicals, antioxidant potential and other bioactivities of Sorbus extracts has revealed the prospects of expanding its use in natural medicines, cosmetics and as innovative food ingredients, which might find wider applications in functional foods and/or nutraceuticals. Caffeoylquinic acids, flavonoids and proanthocyanidins have been reported in various Sorbus spp. as the most abundant polyphenolic antioxidants. The preparations of various plant anatomical parts have been used in ethnopharmacology as natural remedy for treating bacterial, viral, inflammatory diseases including tumors. Sorbus spp. plant parts have also been tested for management of diabetes, neurological, and cardiovascular disorders. The present review is focused on Sorbus plants (in total 27 Sorbus spp.), their composition and properties in terms of developing promising ingredients for foods, nutraceutical, cosmeceutical and other applications. It is expected that this review will assist in designing further studies of rowans and other Sorbus spp. in order to expand their uses for various human applications.

Association between dietary intake and risk of ovarian cancer: a systematic review and meta-analysis

PURPOSE

It is unclear how dietary intake influences the ovarian cancer. The present paper sets out to systematically review and meta-analyze research on dietary intake to identify cases having high- or low-risk ovarian cancer.

METHODS

Scopus, PubMed, and Wiley Online Libraries were searched up to the date November 24, 2019. Two reviewers were requested to independently extract study characteristics and to assess the bias and applicability risks with reference to the study inclusion criteria. Meta-analyses were performed to specify the relationship between dietary intake and the risk of ovarian cancer identifying 97 cohort studies.

RESULTS

No significant association was found between dietary intake and risk of ovarian cancer. The results of subgroup analyses indicated that green leafy vegetables (RR = 0.91, 95%, 0.85-0.98), allium vegetables (RR = 0.79, 95% CI 0.64-0.96), fiber (RR = 0.89, 95% CI 0.81-0.98), flavonoids (RR = 0.83, 95% CI 0.78-0.89) and green tea (RR = 0.61, 95% CI 0.49-0.76) intake could significantly reduce ovarian cancer risk. Total fat (RR = 1.10, 95% CI 1.02-1.18), saturated fat (RR = 1.11, 95% CI 1.01-1.22), saturated fatty acid (RR = 1.19, 95% CI 1.04-1.36), cholesterol (RR = 1.13, 95% CI 1.04-1.22) and retinol (RR = 1.14, 95% CI 1.00-1.30) intake could significantly increase ovarian cancer risk. In addition, acrylamide, nitrate, water disinfectants and polychlorinated biphenyls were significantly associated with an increased risk of ovarian cancer.

CONCLUSION

These results could support recommendations to green leafy vegetables, allium vegetables, fiber, flavonoids and green tea intake for ovarian cancer prevention.

Compositional Analysis of Genetically Engineered GR2E "Golden Rice" in Comparison to That of Conventional Rice

Compositional analyses were performed on samples of rice grain, straw, and derived bran obtained from golden rice event GR2E and near-isogenic control PSBRc82 rice grown at four locations in the Philippines during 2015 and 2016. Grain samples were analyzed for key nutritional components, including proximates, fiber, polysaccharides, fatty acids, amino acids, minerals, vitamins, and antinutrients. Samples of straw and bran were analyzed for proximates and minerals. The only biologically meaningful difference between GR2E and control rice was in levels of β-carotene and other provitamin A carotenoids in the grain. Except for β-carotene and related carotenoids, the compositional parameters of GR2E rice were within the range of natural variability of those components in conventional rice varieties with a history of safe consumption. Mean provitamin A concentrations in milled rice of GR2E can contribute up to 89-113% and 57-99% of the estimated average requirement for vitamin A for preschool children in Bangladesh and the Philippines, respectively.

Lycopene Protects Against Spontaneous Ovarian Cancer Formation in Laying Hens

Background

Dietary intake of lycopene has been associated with a reduced risk of ovarian cancer, suggesting its chemopreventive potential against ovarian carcinogenesis. Lycopene's molecular mechanisms of action in ovarian cancer have not been fully understood. Therefore, in the present study, we investigated the effects of lycopene on the ovarian cancer formation using the laying hen model, a biologically relevant animal model of spontaneous ovarian carcinogenesis due to high incidence rates similar to humans.

Methods

In this study, a total of 150 laying hens at age of 102 weeks were randomized into groups of 50: a control group (0 mg of lycopene per kg of diet) and two treatment groups (200 mg or 400 mg of lycopene per kg of diet, or ~26 and 52 mg/d/hen, respectively). At the end of 12 months, blood, ovarian tissues and tumors were collected.

Results

We observed that lycopene supplementation significantly reduced the overall ovarian tumor incidence (P < 0.01) as well as the number and the size of the tumors (P < 0.004 and P < 0.005, respectively). Lycopene also significantly decreased the rate of adenocarcinoma, including serous and mucinous subtypes (P < 0.006). Moreover, we also found that the serum level of oxidative stress marker malondialdehyde was significantly lower in lycopene-fed hens compared to control birds (P < 0.001). Molecular analysis of the ovarian tumors revealed that lycopene reduced the expression of NF-κB while increasing the expression of nuclear factor erythroid 2 and its major target protein, heme oxygenase 1. In addition, lycopene supplementation decreased the expression of STAT3 by inducing the protein inhibitor of activated STAT3 expression in the ovarian tissues.

Conclusions

Taken together, our findings strongly support the potential of lycopene in the chemoprevention of ovarian cancer through antioxidant and anti-inflammatory mechanisms.

Supplemental Selenium May Decrease Ovarian Cancer Risk in African-American Women

Background: To our knowledge, no previous study has evaluated the associations of antioxidant intake with the risk of ovarian cancer in African-American women, who are known to have high mortality from the disease.Objective: We sought to evaluate these associations among 406 ovarian cancer cases and 632 age- and site-matched controls of African-American descent recruited from AACES (African American Cancer Epidemiology Study), a population-based, case-control study in 11 geographical areas within the United States.Methods: Multivariable logistic regression models were used to estimate ORs and 95% CIs adjusted for a wide range of potentially confounding factors, including age, region, education, parity, oral contraceptive use, menopause, tubal ligation, family history, body mass index (BMI), smoking status, total energy, and physical activity.Results: Women with the highest intakes of supplemental selenium (>20 μg/d) had an ∼30% lower risk of ovarian cancer than those with no supplemental intake (OR: 0.67; 95% CI: 0.46, 0.97; P-trend = 0.035). This inverse association was stronger in current smokers (OR: 0.13; 95% CI: 0.04, 0.46; P-trend = 0.001). There was no association with dietary selenium. The associations with carotenoid intakes were weak and nonsignificant (P = 0.07-0.60). We observed no association with dietary or supplemental intake of vitamin C or vitamin E. There were no appreciable differences in results between serous and nonserous tumors.Conclusions: These findings provide the first insights, to our knowledge, into the potential association between antioxidants and ovarian cancer in African-American women, indicating potential inverse associations with supplemental selenium.

Intake of vitamins A, C, and E and folate and the risk of ovarian cancer in a pooled analysis of 10 cohort studies

PURPOSE

Vitamins A, C, and E and folate have anticarcinogenic properties and thus might protect against cancer. Few known modifiable risk factors for ovarian cancer exist. We examined the associations between dietary and total (food and supplemental) vitamin intake and the risk of invasive epithelial ovarian cancer.

METHODS

The primary data from 10 prospective cohort studies in North America and Europe were analyzed. Vitamin intakes were estimated from validated food frequency questionnaires in each study. Study-specific relative risks (RRs) were estimated using the Cox proportional hazards model and then combined using a random-effects model.

RESULTS

Among 501,857 women, 1,973 cases of ovarian cancer occurred over a median follow-up period of 7-16 years across studies. Dietary and total intakes of each vitamin were not significantly associated with ovarian cancer risk. The pooled multivariate RRs [95% confidence intervals (CIs)] for incremental increases in total intake of each vitamin were 1.02 (0.97-1.07) for vitamin A (increment: 1,300 mcg/day), 1.01 (0.99-1.04) for vitamin C (400 mg/day), 1.02 (0.97-1.06) for vitamin E (130 mg/day), and 1.01 (0.96-1.07) for folate (250 mcg/day). Multivitamin use (vs. nonuse) was not associated with ovarian cancer risk (pooled multivariate RR = 1.00, 95% CI 0.89-1.12). Associations did not vary substantially by study, or by subgroups of the population. Greater vitamin intakes were associated with modestly higher risks of endometrioid tumors (n = 156 cases), but not with other histological types.

CONCLUSION

These results suggest that consumption of vitamins A, C, and E and folate during adulthood does not play a major role in ovarian cancer risk.

β-Cryptoxanthin Synergistically Enhances the Antitumoral Activity of Oxaliplatin through ΔNP73 Negative Regulation in Colon Cancer

BACKGROUND

The acquired resistance to chemotherapy represents the major limitation in the treatment of cancer. New strategies to solve this failure and improve patients' outcomes are necessary. The cancer preventive effect of β-cryptoxanthin has been widely described in population studies. Few reports support its putative use as an antitumoral compound. Here we focus on the therapeutic potential of β-cryptoxanthin individually or in combination with oxaliplatin in colon cancer and try to decipher the molecular basis underlying its effect.

METHODS

Apoptosis, viability and proliferation assays, mouse models, and an intervention study in 20 healthy subjects were performed. A PCR array was carried out to unravel the molecular putative basis of the β-cryptoxanthin effect, and further signaling experiments were conducted. Comet Assay was completed to evaluate the genotoxicity of the treatments.

RESULTS

β-Cryptoxanthin differentially regulates the expression of the P73 variants in vitro, in vivo, and in a human intervention study. This carotenoid decreases the proliferation of cancer cells and cooperates with oxaliplatin to induce apoptosis through the negative regulation of ΔNP73. The antitumoral concentrations of oxaliplatin decrease in the presence of β-cryptoxanthin to achieve same percentage of growth inhibition. The genotoxicity in peripheral blood mononuclear cells of mice decreased in the combined treatment.

CONCLUSIONS

We propose a putative novel therapeutic strategy for the treatment of colon cancer based on the combination of β-cryptoxanthin and oxaliplatin. The combined regimen produced more benefit than either individual modality without increasing side effects. In addition, the concentration-limiting toxicity of oxaliplatin is reduced in the presence of the carotenoid.

An Evidence-Based Systematic Review of Lutein by the Natural Standard Research Collaboration

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

Dietary factors in the etiology of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The majority of cases do not arise from purely genetic factors, implicating an important role of environmental factors in disease pathogenesis. Well-established environmental toxins important in PD include pesticides, herbicides, and heavy metals. However, many toxicants linked to PD and used in animal models are rarely encountered. In this context, other factors such as dietary components may represent daily exposures and have gained attention as disease modifiers. Several in vitro, in vivo, and human epidemiological studies have found a variety of dietary factors that modify PD risk. Here, we critically review findings on association between dietary factors, including vitamins, flavonoids, calorie intake, caffeine, alcohol, and metals consumed via food and fatty acids and PD. We have also discussed key data on heterocyclic amines that are produced in high-temperature cooked meat, which is a new emerging field in the assessment of dietary factors in neurological diseases. While more research is clearly needed, significant evidence exists that specific dietary factors can modify PD risk.

Baseline serum β-carotene concentration and mortality among long-term asbestos-exposed insulators

BACKGROUND

Although interventional trials demonstrated that moderate-dose β-carotene supplementation increases lung cancer mortality in smokers and asbestos-exposed workers, differences in serum concentrations in absence of supplementation have not been studied in asbestos-exposed workers.

METHODS

A mortality analysis was performed to assess the relationship of nonsupplemented serum β-carotene to all-cause and cancer mortalities using 1981 to 1983 serum β-carotene concentration measurements from 2,646 U.S. white male insulators (mean age, 57.7 years). Multivariable-adjusted Cox proportional hazard models that included terms for age, duration of asbestos exposure, smoking, season, and region were fitted to estimate mortality HRs and 95% confidence intervals (CI) according to serum β-carotene concentrations.

RESULTS

Median follow-up was 12.8 years and 984 (33.8%) subjects died during the follow-up period, including 415 deaths from overall cancer and 219 deaths from lung cancer. The overall mortality HR for a serum β-carotene increase of 10 μg/dL was 0.97 (95% CI, 0.96-0.99). Compared with the lowest quartile, HRs were 0.90 (95% CI, 0.76-1.07) for the second (38-65 μg/dL), 0.80 (95% CI, 0.67-0.96) for the third (66-104 μg/dL), and 0.63 (95% CI, 0.51-0.77) for the highest serum β-carotene quartile (≥105 μg/dL). There was no association between serum β-carotene and overall cancer mortality (HR, 1.00; 95% CI, 0.97-1.02) or lung cancer mortality (HR, 0.99; 95% CI, 0.96-1.02).

CONCLUSIONS

Higher nonsupplemented serum β-carotene concentrations were negatively associated with all-cause mortality among asbestos-exposed individuals.

IMPACT

Serum β-carotene can be a marker of one or more determinants of reduced mortality in asbestos-exposed workers. Cancer Epidemiol Biomarkers Prev; 24(3); 555-60. ©2014 AACR.

Meta-analysis of the association between dietary lycopene intake and ovarian cancer risk in postmenopausal women

Accumulating evidence suggests the protective role of dietary lycopene against the risk of ovarian cancer due to its antioxidant activity, but not all relevant studies have deduced positive results. The aim of the present study was to investigate the exact relationship between dietary lycopene intake and ovarian cancer risk by conducting a meta-analysis. The 10 studies included in our meta-analysis were selected from the PubMed database, and final risk estimates were calculated by using a random-effects model. Our study demonstrated an insignificant reverse association between dietary lycopene and ovarian cancer risk (OR, 0.963; 95% CI, 0.859–1.080), and subgroup analysis stratified by study design, location, histological type of ovarian cancer, and length of dietary recall showed no statistically significant results. No heterogeneity was observed (p = 0.336, I² = 11.6%). Our present meta-analysis suggests the potential role of dietary lycopene against the risk of ovarian cancer among postmenopausal women, which provides opportunity for developments in the prevention of ovarian cancer.

Ten misconceptions about antioxidants

Oxidative damage is a common cellular event involved in numerous diseases and drug toxicities. Antioxidants prevent or delay oxidative damage, and therefore there has been extensive research into the discovery of natural and newly designed antioxidants. Initial excitement regarding the potential health benefits of antioxidants has diminished. Currently, it is even claimed that antioxidants increase mortality. The antioxidant pendulum appears to swing from healthy to toxic and from general panacea to insignificant ingredient. Owing to the polarity of views towards antioxidants, nutritional recommendation ranges from advice to increase antioxidant status in plasma to the notion that it is a useless measurement. Such views, lacking sufficient scientific support, lead to misconceptions, which in our opinion hinder the rational use of food supplements and impedes the design and development of new antioxidant drugs. As a result, good opportunities might easily be missed.

Functional properties of carotenoids originating from algae

Carotenoids are isoprenoid molecules which are synthesised de novo by photosynthetic plants, fungi and algae and are responsible for the orange, yellow and some red colours of various fruits and vegetables. Carotenoids are lipophilic compounds, some of which act as provitamins A. These compounds can be divided into xanthophylls and carotenes. Many macroalgae and microalgae are rich in carotenoids, where these compounds aid in the absorption of sunlight. Industrially, these carotenoids are used as food pigments (in dairy products, beverages, etc.), as feed additives, in cosmetics and in pharmaceuticals, especially nowadays when there is an increasing demand by consumers for natural products. Production of carotenoids from algae has many advantages compared to other sources; for example, their production is cheap, easy and environmentally friendly; their extraction is easier, with higher yields, and there is no lack of raw materials or limited seasonal variation. Recently, there has been considerable interest in dietary carotenoids with respect to their antioxidant properties and their ability to reduce the incidence of some chronic diseases where free radicals are involved. Possibly, carotenoids protect cells from oxidative stress by quenching singlet oxygen damage with various mechanisms. Therefore, carotenoids derived from algae could be a leading natural resource in the research for potential functional ingredients.

Phytochemicals and cancer risk: a review of the epidemiological evidence

A number of epidemiological studies have investigated associations between various phytochemicals and cancer risk. Phytoestrogens and carotenoids are the two most commonly studied classes of phytochemicals; phytosterols, isothiocyanates, and chlorophyll also have been investigated, although to a much lesser extent. Because there have been no systematic reviews of the literature on all phytochemicals and cancer risk to date, this article systematically reviews 96 published epidemiological studies that examined associations between phytochemicals and cancer risk. Most studies found null associations between individual phytochemicals and cancer risk at various sites. In addition, results from past studies have been largely inconsistent, and observed associations have been of relatively modest magnitude. The most consistent protective effects were observed for higher levels--dietary intake, serum, plasma, or urinary metabolites--of β-carotene and renal cell cancer, β-cryptoxanthin and lung cancer, isothiocyanates and lung cancer, isothiocyanates and gastrointestinal cancer, lignans and postmenopausal breast cancer, and flavonoids and lung cancer. Although elevated risk of certain cancers with higher levels of certain phytochemicals was observed, an insufficient pool of studies examining the same associations or inconsistent findings across studies limit the ability to conclude that any one phytochemical increases cancer risk. Additional research is needed to support previously identified associations in cases where only one study has examined a particular relationship. Importantly, continued research efforts are needed to evaluate the cumulative and interactive effects of numerous phytochemicals and phytochemical-rich foods on cancer risk.

Concordance of randomized and nonrandomized studies was unrelated to translational patterns of two nutrient-disease associations

OBJECTIVE

There are several examples in nutrition of discordance between the results of observational studies and randomized controlled trials (RCTs). We hypothesized that this discordance is attributable to differences in the translational paths of nutrient-disease associations. Translational paths can be assessed using citation analysis.

STUDY DESIGN AND SETTING

We compared the characteristics of citation networks using examples, where RCTs and observational studies agreed (long-chain n-3 polyunsaturated fatty acids [n-3 PUFA]) or disagreed (vitamin E). We performed systematic reviews in each example, constructed citation networks, and compared them with respect to the number of articles and citation relationships between them, as well as the distribution of articles' hub and authority scores.

RESULTS

For n-3 PUFA, meta-analyses of 14 RCTs and 10 observational studies both suggested that higher intake was associated with lower cardiovascular mortality. For vitamin E, the meta-analysis of 14 RCTs excluded a clinically significant effect, whereas 14 observational studies reported a significant inverse association. The respective citation networks consisted of 392 (n-3 PUFA) and 351 (vitamin E) articles. No differences between the characteristics of the two networks were identified. There was no evidence that the observational studies predated RCTs in the translational process in either example.

CONCLUSION

In the two examples, citation network characteristics do not predict concordance in the results of observational studies and RCTs.

The effect of food preparation on the bioavailability of carotenoids from carrots using intrinsic labelling

A strategy to reduce the incidence of vitamin A deficiency is to improve precursor bioavailability from meals. Since vitamin A precursors are fat-soluble, we noted that carotenoids are more easily absorbed from food if prepared in such a way that the food matrix containing provitamin A (β-carotene) is sufficiently fat rich. To quantify this effect, we have developed a stable isotope methodology. By regular watering with2H-labelled water, we were able to produce several kg of intrinsically labelled carrots, with carotenoids labelled to 0·63 % excess2H. These were divided into 100 g portions and fed to a small group of healthy subjects both raw and stir-fried. To normalise for inter-individual variation in absorption and subsequent metabolism, small quantities of extrinsically13C-labelled β-carotene and2H-labelled retinol acetate were also incorporated into the meal. After ingestion of the carrots, blood lipids were monitored for a period of 3 d in order to determine the kinetics of β-carotene and retinol. From kinetic data, it was estimated that the bioavailability of carrot-derived β-carotene compared with pure β-carotene was about 11 % for raw carrots, but 75 % when the carrots were stir-fried. Conversely, there was a slight reduction in the bioconversion to retinol from β-carotene when the latter was derived from the stir-fried meal compared with that from raw carrots. When these two factors are combined, the yield of retinol from the carotene in carrots was found to be enhanced by a factor of 6·5 by stir-frying.

Phytochemicals in the oncology setting

Phytochemicals--the bioactive compounds found in plants--not only hold historical significance in various medical traditions, but also form the basis of many modern-day drugs. Phytochemicals are often used for primary disease prevention or as adjuncts to conventional therapies--despite uncertain effectiveness or safety. On the other hand, phytochemicals have given rise to numerous conventional drugs, which are widely used in mainstream medicine and compose the primary therapeutic strategies for numerous conditions (including cancer). In this review, we will discuss general safety considerations for integrating phytochemicals in the oncology setting. The supportive evidence and safety concerns of popular plant-based cancer therapies will also be summarized. Finally, a brief overview of the established and emerging anticancer drugs with botanical origins will be provided.

Red and processed meat consumption and risk of ovarian cancer: a dose-response meta-analysis of prospective studies

Background:

During the last decade, the epidemiological evidence on consumption of meat and risk of ovarian cancer has accumulated.

Methods:

We assessed the relationship between red and processed meat consumption and risk of ovarian cancer with a dose-response meta-analysis. Relevant prospective cohort studies were identified by searching the PubMed and EMBASE databases through 21 January 2011, and by reviewing the reference lists of retrieved articles. Study-specific relative risk (RR) estimates were combined using a random-effects model.

Results:

Eight cohort studies were included in the meta-analysis. The summary RR for an intake increment of 100 g per week was 1.02 (95% confidence interval (CI), 0.99–1.04) for red meat and 1.05 (95% CI, 0.98–1.14) for processed meat. For an intake increment of four servings per week, the summary RR of ovarian cancer was 1.07 (95% CI, 0.97–1.19) for red meat (100 g per serving) and 1.07 (95% CI, 0.97–1.17) for processed meat (30 g per serving).

Conclusion:

Results from this dose-response meta-analysis suggest that red and processed meat consumption is not associated with risk of ovarian cancer. Although a lower consumption of red and processed meat may offer protection against other types of cancer, other interventions are needed to reduce the risk of ovarian cancer.

Smoking attenuates the negative association between carotenoids consumption and colorectal cancer risk

OBJECTIVES

Consumption of vegetables and fruits, physical activity, obesity and caloric intake are all strongly related to the risk of colorectal cancer (CRC). The association between dietary intake of carotenoids from vegetables/fruits and risk of CRC in the context of cigarette smoking was studied in a nutritionally diverse population.

METHODS

The study included 1,817 age sex residence-matched case-control pairs from a population-based study in Northern Israel. Data were acquired by food-frequency questionnaire. Individual intake of carotenoid isomers was calculated using an Israeli food content database. Odds ratios (ORs) were calculated using conditional logistic regression models adjusted for known risk factors.

RESULTS

Strong inverse associations were found with consumption of 9-cis-beta-carotene (OR = 0.35, 0.26-0.47), all-trans-beta-carotene (OR = 0.58, 0.44-0.76), cis-beta-cryptoxanthin (OR = 0.67, 0.50-0.90), all-trans-zeaxanthin (OR = 0.64, 0.48-0.86), and lutein (OR = 0.74, 0.57-0.96). Lycopene (OR = 2.22, 1.71-2.89) and all-trans-beta-cryptoxanthin (OR = 2.01, 1.48-2.73) were associated with increased risk of CRC. Inverse associations of most carotenoids with CRC, demonstrated in non-smokers, were much attenuated or reversed in past or current smokers with a highly significant interaction term.

CONCLUSIONS

Consumption of most dietary carotenoids was found to be strongly associated with reduced risk of CRC. However, smoking significantly attenuated or reversed this observed protective effect on CRC occurrence. Smokers should be advised that smoking also hampers the potential health promoting effects of high fruit and vegetable consumption.

Nutrition and health: guidelines for dental practitioners

Good nutrition is vital to overall health, and poor diet and a sedentary lifestyle are major causes of morbidity and mortality worldwide. Nutritional factors are implicated in many oral and systemic diseases and conditions, including obesity, hypertension, dyslipidemia, type II diabetes, cardiovascular disease, osteoporosis, dental caries and some cancers including oral cancers. This review focuses on the evidence for the relations between key nutritional factors and health. Energy intake is related to body weight and obesity, highlighting the importance of lower-energy diets and regular physical activity for body weight maintenance and for preventing obesity. Evidence is presented for the health benefits of high quality carbohydrates, such as whole grain products, and fruits and vegetables, in reducing the risk of cardiovascular disease and cancer. The adverse effects of sugar, sweetened beverages, and trans and saturated fats on several diseases including caries, diabetes and cardiovascular disease are described. The health benefits of unsaturated fats, antioxidants, B vitamins and vitamin D in cardiovascular disease, periodontitis, cancer, and other conditions are documented. Both benefits and harmful effects of dairy product intake on health are discussed. Based on the evidence, nutritional guidelines are provided, as well as key recommendations for preventing obesity. Dentists can play a critical role in motivating and enabling healthy food choices.

The role of antioxidants and vitamin A in ovarian cancer: results from the Women's Health Initiative

Antioxidant nutrients and carotenoids have been inconsistently associated with ovarian cancer risk. We examined the relationship between intake of dietary and supplemental antioxidant nutrients including vitamins C, E, and selenium as well as carotenoids and vitamin A and ovarian cancer in 133,614 postmenopausal women enrolled in the Women's Health Initiative (WHI) study. Dietary intake was assessed using a food frequency questionnaire, and ovarian cancer endpoints were centrally adjudicated. Cox regression models were used to estimate the risk for invasive ovarian cancer in relation to each of the antioxidant nutrients and carotenoids under consideration using models stratified for a WHI study component. A total of 451 cases of invasive ovarian cancer were diagnosed over 8.3 yr of follow-up. Dietary intake at baseline was not significantly different for cases vs. controls. Cases reported greater intake of supplemental vitamin C (358.0 mg/day vs. 291.6 mg/day, respectively; P = 0.024). Multivariate modeling (P for trend) of the risk for developing ovarian cancer did not suggest any significant relationships among dietary factors and ovarian cancer risk. The results from this prospective study of well-nourished, postmenopausal women suggest that intake of dietary antioxidants, carotenoids, and vitamin A are not associated with a reduction in ovarian cancer risk.

Vitamins C and E and beta carotene supplementation and cancer risk: a randomized controlled trial

BACKGROUND

Observational studies suggested that a diet high in fruits and vegetables, both of which are rich with antioxidants, may prevent cancer development. However, findings from randomized trials of the association between antioxidant use and cancer risk have been mostly negative.

METHODS

From 8171 women who were randomly assigned in the Women's Antioxidant Cardiovascular Study, a double-blind, placebo-controlled 2 x 2 x 2 factorial trial of vitamin C (500 mg of ascorbic acid daily), natural-source vitamin E (600 IU of alpha-tocopherol every other day), and beta carotene (50 mg every other day), 7627 women who were free of cancer before random assignment were selected for this study. Diagnoses and deaths from cancer at a specific site were confirmed by use of hospital reports and the National Death Index. Cox proportional hazards regression models were used to assess hazard ratios (represented as relative risks [RRs]) of common cancers associated with use of antioxidants, either individually or in combination. Subgroup analyses were conducted to determine if duration of use modified the association of supplement use with cancer risk. All statistical tests were two-sided.

RESULTS

During an average 9.4 years of treatment, 624 women developed incident invasive cancer and 176 women died from cancer. There were no statistically significant effects of use of any antioxidant on total cancer incidence. Compared with the placebo group, the RRs were 1.11 (95% confidence interval [CI] = 0.95 to 1.30) in the vitamin C group, 0.93 (95% CI = 0.79 to 1.09) in the vitamin E group, and 1.00 (95% CI = 0.85 to 1.17) in the beta carotene group. Similarly, no effects of these antioxidants were observed on cancer mortality. Compared with the placebo group, the RRs were 1.28 (95% CI = 0.95 to 1.73) in the vitamin C group, 0.87 (95% CI = 0.65 to 1.17) in the vitamin E group, and 0.84 (95% CI = 0.62 to 1.13) in the beta carotene group. Duration and combined use of the three antioxidants also had no effect on cancer incidence and cancer death.

CONCLUSIONS

Supplementation with vitamin C, vitamin E, or beta carotene offers no overall benefits in the primary prevention of total cancer incidence or cancer mortality.

Dietary patterns and risk of ovarian cancer in the California Teachers Study cohort

Previous studies have examined the association between individual foods or nutrients, but not overall diet, and ovarian cancer risk. To account for the clustering of foods in the diet, we investigated the association between dietary patterns and risk of ovarian cancer in the prospective California Teachers Study cohort. Of 97,292 eligible women who completed the baseline dietary assessment in 1995-1996, 311 women developed epithelial ovarian cancer on or before December 31, 2004. Based on principal components analysis, 5 major dietary patterns were identified and termed plant-based, high-protein/high-fat, high-carbohydrate, ethnic, and salad-and-wine. Multivariable Cox proportional hazards regression analysis was used to estimate associations between these dietary patterns and risk of incident ovarian cancer. Most of the dietary patterns were not significantly associated with ovarian cancer risk. However, women who followed a plant-based diet had higher risk; comparing those in the top quintile of plant-based food intake with those in the lowest quintile, the relative risk of ovarian cancer was 1.65 (95% confidence interval = 1.07-2.54; P(trend) = 0.03). Associations with the 5 dietary patterns did not vary by known ovarian cancer risk factors or other behavioral or sociodemographic characteristics. Overall, our results show no convincing associations between dietary patterns and ovarian cancer risk.

Intake of specific carotenoids and the risk of epithelial ovarian cancer

There has been considerable interest in the role of carotenoids in the chemoprevention of cancer. However, few studies have examined the association between intake of specific carotenoids and the risk of epithelial ovarian cancer and the results for carotenoids have been inconclusive. To investigate whether the intake of α-carotene, β-carotene, β-cryptoxanthin, lutein and zeaxanthin, and lycopene is inversely associated with ovarian cancer risk, a case–control study was conducted in China during 1999–2000. The cases were 254 patients with histologically confirmed epithelial ovarian cancer and 652 age-matched controls were randomly recruited during the same period. Habitual dietary intake and lifestyle were collected by face-to-face interview using a validated and reliable FFQ. The US Department of Agriculture nutrient composition database was used to calculate the intake of specific carotenoids. Unconditional logistic regression analyses were used to estimate OR and 95 % CI, accounting for age, locality, education, BMI, smoking, tea drinking, parity, oral contraceptive use, hormone replacement therapy, menopausal status, family history of ovarian cancer, physical activity and energy intake. Compared with the highest v. the lowest quartile of intake, the adjusted OR were 0·39 (95 % CI 0·23, 0·66) for α-carotene, 0·51 (95 % CI 0·31, 0·84) for β-carotene, 0·51 (95 % CI 0·31, 0·83) for β-cryptoxanthin, 0·45 (0·27, 0·76) for lutein and zeaxanthin, and 0·33 (95 % CI 0·20, 0·56) for total carotenoids, with statistically significant tests for trend. It is concluded that a higher intake of carotenoids can reduce the risk of epithelial ovarian cancer.

Nutrient dietary patterns and the risk of breast and ovarian cancers

The issue of diet and breast and ovarian cancers has been considered in terms of foods and nutrients, but rarely in terms of dietary patterns. We examined the associations between dietary patterns and breast and ovarian cancers in 2 Italian multicentric case-control studies. Cases were 2,569 breast cancers and 1,031 ovarian cancers hospitalized in 4 Italian areas between 1991 and 1999. Controls were 3,413 women from the same hospital network. Dietary habits were investigated through a validated food-frequency questionnaire. Dietary patterns were identified on a selected set of nutrients through principal component factor analysis. Odds ratios (OR) and 95% confidence intervals (CI) for both cancers were estimated using unconditional multiple logistic regression models on quartiles of factor scores and continuous factor scores. We identified 4 major dietary patterns named Animal products, Vitamins and fiber, Unsaturated fats and Starch-rich. The animal products pattern and the unsaturated fats pattern were inversely associated with breast cancer (OR = 0.74, 95% CI: 0.61-0.91 and OR = 0.83, 95% CI: 0.68-1.00, respectively, for the highest consumption quartile), whereas the starch-rich pattern was directly associated with it (OR = 1.34, 95% CI: 1.10-1.65). The vitamins and fiber pattern was inversely associated with ovarian cancer (OR = 0.77, 95% CI: 0.61-0.98), whereas the starch-rich pattern was directly associated with it (OR = 1.85, 95% CI: 1.37-2.48). In conclusion, the starch-rich pattern is potentially an unfavorable indicator of risk for both breast and ovarian cancers, while the animal products and the vitamins and fiber patterns may be associated with a reduced risk of breast and ovarian cancers, respectively.