Can Diet Prevent Urological Cancers? An Update on Carotenoids as Chemopreventive Agents

Urological cancers, namely prostate, bladder, kidney, testicular, and penile cancers, are common conditions that constitute almost one-quarter of all malignant diseases in men. Urological cancers tend to affect older individuals, and their development is influenced by modifiable metabolic, behavioral, and environmental risk factors. Phytochemicals may have cancer-fighting properties and protect against cancer development, slow its spread, and reduce the risk of cancer deaths in humans. This paper aims to review the current literature in regard to the effects of carotenoids in reducing urological cancer risk.     

Association of Dietary Vitamin A and β-Carotene Intake with the Risk of Lung Cancer: A Meta-Analysis of 19 Publications

Whether dietary β-carotene and vitamin A intake protect against lung cancer risk is not clear. Therefore, we performed this meta-analysis to investigate the association between them. The related articles were searched using the databases PubMed and the Web of Knowledge up to May 2015. We used the random-effect model to estimate the relative risk (RR) and their 95% CI. Small-study effect was assessed using Egger’s test. In total, 19 studies comprising 10,261 lung cancer cases met the inclusion criteria. The pooled RR and their 95% CI was 0.855 (0.739–0.989) for higher category of dietary vitamin A intake and lung cancer risk, especially among Asian populations and in the cohort studies. Evidence from 18 studies suggested that higher category of dietary β-carotene intake could reduce lung cancer risk (0.768 (0.675–0.874)).The associations were also significant in American and Asian populations. In conclusions, higher category of dietary β-carotene and vitamin A intakes could reduce the risk of lung cancer. However, the dose-response analysis was not performed due to the limited data in each individual study. Due to this limitation, further studies with detailed dose, cases and person-years for β-carotene and vitamin A of each category are wanted to assess this dose-response association.     

Food Predictors of Plasma Carotenoids

Empirical prediction models that weight food frequency questionnaire (FFQ) food items by their relation to nutrient biomarker concentrations may estimate nutrient exposure better than nutrient intakes derived from food composition databases. Carotenoids may especially benefit because contributing foods vary in bioavailability and assessment validity. Our objective was to develop empirical prediction models for the major plasma carotenoids and total carotenoids and evaluate their validity compared with dietary intakes calculated from standard food composition tables. 4180 nonsmoking women in the Nurses’ Health Study (NHS) blood subcohort with previously measured plasma carotenoids were randomly divided into training (n = 2787) and testing (n = 1393) subsets. Empirical prediction models were developed in the training subset by stepwise selection from foods contributing ≥0.5% to intake of the relevant carotenoid. Spearman correlations between predicted and measured plasma concentrations were compared to Spearman correlations between dietary intake and measured plasma concentrations for each carotenoid. Three to 12 foods were selected for the α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin, lycopene, and total carotenoids prediction models. In the testing subset, Spearman correlations with measured plasma concentrations for the calculated dietary intakes and predicted plasma concentrations, respectively, were 0.31 and 0.37 for α-carotene, 0.29 and 0.31 for β-carotene, 0.36 and 0.41 for β-cryptoxanthin, 0.28 and 0.31 for lutein/zeaxanthin, 0.22 and 0.23 for lycopene, and 0.22 and 0.27 for total carotenoids. Empirical prediction models may modestly improve assessment of some carotenoids, particularly α-carotene and β-cryptoxanthin.     

The European prospective investigation about cancer and nutrition (EPIC)

EPIC is a prospective multi-center study coordinated by the International Agency for Research on Cancer (IARC) operating under the WHO which commenced in 1993 with the collecting of data and blood samples at twenty-three centers in ten European countries (Germany, Denmark, Spain, France, Greece, the Netherlands, Italy, Norway, the United Kingdom and Sweden). In Spain, this study was conducted in five geographic areas (Asturias, Granada, Guipuzcoa, Murcia and Navarre). This study included a total of 519,978 individuals (366,521 of whom were females), blood samples for laboratory analysis being available for a total of 385,719 of these individuals. To date, a total of 24,195 incident cancer cases have been identified. The results of the food intake comparison among the twenty-three European centers were published in 2002, in a European Nutrition journal supplement. The initial EPIC results concerning the relationship between diet and cancer show the intake of fiber, fruits and vegetables to have an effect on protect against colon and rectal cancer, the intake of fruits to have an effect on protect against lung cancer and the intake of fruits and vegetables on the upper digestive tract, whilst a high intake of fruits and vegetables has been shown to have no effect on prostate cancer. Using a seven-day diary for evaluating saturated fat intake, a high intake of saturated fats has been shown to increase the risk of breast cancer.     

Carotenoid intake and head and neck cancer: a pooled analysis in the International Head and Neck Cancer Epidemiology Consortium

Food and nutrition play an important role in head and neck cancer (HNC) etiology; however, the role of carotenoids remains largely undefined. We explored the relation of HNC risk with the intake of carotenoids within the International Head and Neck Cancer Epidemiology Consortium. We pooled individual-level data from 10 case–control studies conducted in Europe, North America, and Japan. The analysis included 18,207 subjects (4414 with oral and pharyngeal cancer, 1545 with laryngeal cancer, and 12,248 controls), categorized by quintiles of carotenoid intake from natural sources. Comparing the highest with the lowest quintile, the risk reduction associated with total carotenoid intake was 39 % (95 % CI 29–47 %) for oral/pharyngeal cancer and 39 % (95 % CI 24–50 %) for laryngeal cancer. Intakes of β-carotene equivalents, β-cryptoxanthin, lycopene, and lutein plus zeaxanthin were associated with at least 18 % reduction in the rate of oral and pharyngeal cancer (95 % CI 6–29 %) and 17 % reduction in the rate of laryngeal cancer (95 % CI 0–32 %). The overall protective effect of carotenoids on HNC was stronger for subjects reporting greater alcohol consumption (p < 0.05). The odds ratio for the combined effect of low carotenoid intake and high alcohol or tobacco consumption versus high carotenoid intake and low alcohol or tobacco consumption ranged from 7 (95 % CI 5–9) to 33 (95 % CI 23–49). A diet rich in carotenoids may protect against HNC. Persons with both low carotenoid intake and high tobacco or alcohol are at substantially higher risk of HNC.     

A carotenoid health index based on plasma carotenoids and health outcomes

While there have been many studies on health outcomes that have included measurements of plasma carotenoids, this data has not been reviewed and assembled into a useful form. In this review sixty-two studies of plasma carotenoids and health outcomes, mostly prospective cohort studies or population-based case-control studies, are analyzed together to establish a carotenoid health index. Five cutoff points are established across the percentiles of carotenoid concentrations in populations, from the tenth to ninetieth percentile. The cutoff points (mean ± standard error of the mean) are 1.11 ± 0.08, 1.47 ± 0.08, 1.89 ± 0.08, 2.52 ± 0.13, and 3.07 ± 0.20 μM. For all cause mortality there seems to be a low threshold effect with protection above every cutoff point but the lowest. But for metabolic syndrome and cancer outcomes there tends to be significant positive health outcomes only above the higher cutoff points, perhaps as a triage effect. Based on this data a carotenoid health index is proposed with risk categories as follows: very high risk: <1 μM, high risk: 1-1.5 μM, moderate risk: 1.5-2.5 μM, low risk: 2.5-4 μM, and very low risk: >4 μM. Over 95 percent of the USA population falls into the moderate or high risk category of the carotenoid health index.     

蔬菜水果摄入与前列腺癌风险的Meta分析

目的 系统评价蔬菜水果摄入与前列腺癌(prostate cancer,PCa)风险之间的关系,为前列腺癌的预防策略提供相关依据.方法 计算机检索Pubmed、Embase、Web of science数据库,查找评价蔬菜和/或水果摄入与前列腺癌风险之间关系的队列研究以及相关文献,对纳入的文献进行质量评级,采用R软件(4...     

Potential Role of Carotenoids as Antioxidants in Human Health and Disease

Carotenoids constitute a ubiquitous group of isoprenoid pigments. They are very efficient physical quenchers of singlet oxygen and scavengers of other reactive oxygen species. Carotenoids can also act as chemical quenchers undergoing irreversible oxygenation. The molecular mechanisms underlying these reactions are still not fully understood, especially in the context of the anti- and pro-oxidant activity of carotenoids, which, although not synthesized by humans and animals, are also present in their blood and tissues, contributing to a number of biochemical processes. The antioxidant potential of carotenoids is of particular significance to human health, due to the fact that losing antioxidant-reactive oxygen species balance results in “oxidative stress”, a critical factor of the pathogenic processes of various chronic disorders. Data coming from epidemiological studies and clinical trials strongly support the observation that adequate carotenoid supplementation may significantly reduce the risk of several disorders mediated by reactive oxygen species. Here, we would like to highlight the beneficial (protective) effects of dietary carotenoid intake in exemplary widespread modern civilization diseases, i.e., cancer, cardiovascular or photosensitivity disorders, in the context of carotenoids’ unique antioxidative properties.     

β-Carotene and Other Carotenoids as Antioxidants

Carotenoids are natural pigments which are synthesized by plants and are responsible for the bright colors of various fruits and vegetables. There are several dozen carotenoids in the foods that we eat, and most of these carotenoids have antioxidant activity. β-carotene has been best studied since, in most countries it is the most common carotenoid in fruits and vegetables. However, in the U.S., lycopene from tomatoes now is consumed in approximately the same amount as β-carotene. Antioxidants (including carotenoids) have been studied for their ability to prevent chronic disease. β-carotene and others carotenoids have antioxidant properties in vitro and in animal models. Mixtures of carotenoids or associations with others antioxidants (e.g. vitamin E) can increase their activity against free radicals. The use of animals models for studying carotenoids is limited since most of the animals do not absorb or metabolize carotenoids similarly to humans.

Epidemiologic studies have shown an inverse relationship between presence of various cancers and dietary carotenoids or blood carotenoid levels. However, three out of four intervention trials using high dose β-carotene supplements did not show protective effects against cancer or cardiovascular disease. Rather, the high risk population (smokers and asbestos workers) in these intervention trials showed an increase in cancer and angina cases. It appears that carotenoids (including β-carotene) can promote health when taken at dietary levels, but may have adverse effects when taken in high dose by subjects who smoke or who have been exposed to asbestos. It will be the task of ongoing and future studies to define the populations that can benefit from carotenoids and to define the proper doses, lengths of treatment, and whether mixtures, rather than single carotenoids (e.g. β-carotene) are more advantageous.     

Plasma carotenoid levels in Dutch men and women, and the relation with vegetable and fruit consumption

OBJECTIVE: Fruit and vegetable intake is inversely associated with cancer risk in many epidemiological studies. Accurate assessment of consumption of these foods is difficult, and biomarkers of intake would overcome several drawbacks of currently used dietary assessment methods. Therefore, we investigated the relation between plasma carotenoids and usual vegetable and fruit intake. DESIGN: Plasma carotenoid concentrations were measured and vegetable, fruit and juice consumption was assessed by a food frequency questionnaire (FFQ) in a random sample of 591 Dutch men and women aged 20-59 y from the MORGEN-project, one of the contributions to the European Prospective Investigation into Cancer and Nutrition (EPIC)-study. RESULTS: In this sample of the general Dutch population, in both genders, relative to the other carotenoids, plasma beta-cryptoxanthin was the best indicator for fruit intake, and for the sum of vegetable, fruit and juice intake, while lutein concentrations best reflected intake of vegetables, although quartiles of intake were not consistently separated. Since levels of lycopene were not associated with any of the main food groups examined, associations with total carotenoids improved when excluding lycopene, and monotonously increasing plasma levels were seen for intakes of vegetables, of fruits, and of the sum of vegetables, fruits and juices. Several vegetable types and orange/grapefruit juice were associated with plasma levels of one of the carotenoids. CONCLUSION: Plasma carotenoids were only crude indicators of vegetable and fruit intake as assessed by a FFQ; beta-cryptoxanthin for fruit intake and lutein for vegetable intake. None of the plasma carotenoids could distinguish all four quartiles of vegetables, fruit and/or juice intake.     

Dietary carotenoids,serum beta-carotene,and retinol and risk of lung cancer in the alpha-tocopherol,beta-carotene cohort study

Findings from several beta-carotene supplementation trials were unexpected and conflicted with most observational studies. Carotenoids other than beta-carotene are found in a variety of fruits and vegetables and may play a role in this important malignancy, but previous findings regarding the five major carotenoids are inconsistent. The authors analyzed the associations between dietary beta-carotene, beta-carotene, lutein/zeaxanthin, lycopene, beta-cryptoxanthin, vitamin A, serum beta-carotene, and serum retinol and the lung cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of male smokers conducted in southwestern Finland between 1985 and 1993. Of the 27,084 male smokers aged 50-69 years who completed the 276-food item dietary questionnaire at baseline, 1,644 developed lung cancer during up to 14 years of follow-up. Cox proportional hazards models were used to estimate relative risks and 95% confidence intervals. Consumption of fruits and vegetables was associated with a lower lung cancer risk (relative risk = 0.73, 95% confidence interval: 0.62, 0.86, highest vs. lowest quintile). Lower risks of lung cancer were observed for the highest versus the lowest quintiles of lycopene (28%), lutein/zeaxanthin (17%), beta-cryptoxanthin (15%), total carotenoids (16%), serum beta-carotene (19%), and serum retinol (27%). These findings suggest that high fruit and vegetable consumption, particularly a diet rich in carotenoids, tomatoes, and tomato-based products, may reduce the risk of lung cancer.     

A review of epidemiologic evidence that carotenoids reduce the risk of cancer

The epidemiologic evidence that carotenoids are involved in cancer etiology is evaluated. Low intake of vegetables and fruits and carotenoids is consistently associated with an increased risk of lung cancer in both prospective and retrospective studies. In addition, low levels of serum or plasma beta-carotene are consistently associated with the subsequent development of lung cancer. The simplest explanation is that beta-carotene is indeed protective. Since retinol is not related in a similar manner to lung cancer risk, beta-carotene seems to play a role that does not require its conversion into vitamin A. However, the importance of other carotenoids, other constituents of vegetables and fruits, and other nutrients whose levels in the blood are partially correlated with those of beta-carotene has not been adequately explored. In addition, smoking, a powerful risk factor for lung cancer, is associated with reduced intake of carotenoids and lowered blood levels of beta-carotene and has not always been adequately controlled in these analyses. Prospective and retrospective studies suggest that carotenoids may reduce the risk of certain other cancers; however, too few studies have looked at these sites to examine the consistency of the evidence. Although clinical trials of the efficacy of beta-carotene in cancer prevention are underway, it is still necessary and prudent to continue well-designed prospective and retrospective studies of the carotenoid hypothesis.     

Effect of Carotenoids on Paraoxonase-1 Activity and Gene Expression

Paraoxonase 1 (PON1) is an antioxidant enzyme attached to HDL with an anti-atherogenic potential. It protects LDL and HDL from lipid peroxidation. The enzyme is sensitive to various modulating factors, such as genetic polymorphisms as well as pharmacological, dietary (including carotenoids), and lifestyle interventions. Carotenoids are nutritional pigments with antioxidant activity. The aim of this review was to gather evidence on their effect on the modulation of PON1 activity and gene expression. Carotenoids administered as naturally occurring nutritional mixtures may present a synergistic beneficial effect on PON1 status. The effect of carotenoids on the enzyme depends on age, ethnicity, gender, diet, and PON1 genetic variation. Carotenoids, especially astaxanthin, β-carotene, and lycopene, increase PON1 activity. This effect may be explained by their ability to quench singlet oxygen and scavenge free radicals. β-carotene and lycopene were additionally shown to upregulate PON1 gene expression. The putative mechanisms of such regulation involve PON1 CpG-rich region methylation, Ca(2+)/calmodulin-dependent kinase II (CaMKKII) pathway induction, and upregulation via steroid regulatory element-binding protein-2 (SREBP-2). More detailed and extensive research on the mechanisms of PON1 modulation by carotenoids may lead to the development of new targeted therapies for cardiovascular diseases.     

Fruits and vegetables intake differentially affects estrogen receptor negative and positive breast cancer incidence rates

Despite intensive research, the evidence for a protective effect of fruits and vegetables on breast cancer risk remains inconclusive. Other risk factors for breast cancer seem to vary with the estrogen receptor status of the breast tumor, and it is thus possible that the inconsistent results regarding a preventive effect of fruits and vegetables are due to lack of controlling for estrogen receptor status. The objective of this study was to investigate the effect of fruit and vegetable intake on postmenopausal breast cancer and explore whether the estrogen receptor status of the tumor modifies this relation. Postmenopausal women (n = 23,798; aged 50-64 y) provided information about diet and established risk factors for breast cancer in the cohort "Diet, Cancer and Health." During follow-up, 425 cases were diagnosed with breast cancer. Associations between intake of fruits and vegetables and the breast cancer rate were analyzed using Cox's regression model. The association for all breast cancers was an incidence rate ratio (IRR) of 1.02 (95% CI, 0.98-1.06) per 100 g/d increment of total intake of fruits, vegetables and juice. For estrogen receptor-positive (ER(+)) breast cancer, a borderline significant increase in the rate was seen, IRR: 1.05 (95% CI, 1.00-1.10), whereas a preventive effect was seen for estrogen receptor-negative (ER(-)) breast cancers, IRR: 0.90 (95% CI, 0.81-0.99). In conclusion, we did not find the overall breast cancer rate to be associated with the intake of fruits and vegetables, but there seemed to be different effects for ER(+) and ER(-) breast cancer.     

Fruits,vegetables, and adenomatous polyps: the Minnesota Cancer Prevention Research Unit case-control study

Although high vegetable intakes have been associated with a lower risk of colorectal cancer, this relation is less well established for the precursor lesions, adenomatous polyps. With a case-control design involving adenomatous polyp cases (n = 564), colonoscopy-negative controls who were polyp free at colonoscopy (n = 682), and community controls (n = 535), this 1991-1994 Minnesota Cancer Prevention Research Unit study investigated the relation between fruit and vegetable consumption and first incident adenomatous polyps. Dietary intake was assessed using a food frequency questionnaire. For women, adenoma risk was approximately halved in the highest versus lowest quintile of juice consumption (cases vs. colonoscopy-negative controls: odds ratio (OR) = 0.50, 95% confidence interval (CI): 0.27, 0.92; cases vs. community controls: OR = 0.56, 95% CI: 0.30, 1.06). The association was stronger for adenomas with moderate or severe dysplasia compared with mild dysplasia. Juice was not associated with adenoma risk in men. The results for fruits, vegetables, total fruits and vegetables, green leafy vegetables, and several botanically and phytochemically defined subgroups generally were not statistically significant. Because elevated vegetable consumption has been associated with a lower risk of colorectal cancer, vegetables may have a stronger role in preventing the progression of adenomas to carcinomas rather than in preventing the initial appearance of adenomas.     

Diet and PPARG2 Pro12Ala Polymorphism Interactions in Relation to Cancer Risk: A Systematic Review

Peroxisome proliferator-activated receptor-γ2 gene Pro12Ala allele polymorphism (PPARG2 Pro12Ala; rs1801282) has been linked to both cancer risk and dietary factors. We conducted the first systematic literature review of studies published before December 2020 using the PubMed database to summarize the current evidence on whether dietary factors for cancer may differ by individuals carrying C (common) and/or G (minor) alleles of the PPARG2 Pro12Ala allele polymorphism. The inclusion criteria were observational studies that investigated the association between food or nutrient consumption and risk of incident cancer stratified by PPARG2 Pro12Ala allele polymorphism. From 3815 identified abstracts, nine articles (18,268 participants and 4780 cancer cases) covering three cancer sites (i.e., colon/rectum, prostate, and breast) were included. CG/GG allele carriers were more impacted by dietary factors than CC allele carriers. High levels of protective factors (e.g., carotenoids and prudent dietary patterns) were associated with a lower cancer risk, and high levels of risk factors (e.g., alcohol and refined grains) were associated with a higher cancer risk. In contrast, both CG/GG and CC allele carriers were similarly impacted by dietary fats, well-known PPAR-γ agonists. These findings highlight the complex relation between PPARG2 Pro12Ala allele polymorphism, dietary factors, and cancer risk, which warrant further investigation.     

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.     

Relationship between serum carotenoids and hyperglycemia: a population-based cross-sectional study

The present study investigated the relationship between hyperglycemia and both serum carotenoids and intake of vegetables and fruits. Subjects with a history of diabetes mellitus (DM group, n = 133) or with hyperglycemia diagnosed using a 5.6% cutoff value for hemoglobin A1c (High HbA1c group, n = 151) were recruited from among inhabitants of a rural area in Hokkaido, Japan. Intake frequencies of vegetables and fruits were assessed using a questionnaire administered by public health nurses. Serum levels of carotenoids and retinol were measured using high-performance liquid chromatography. The relationships between high HbA1c or DM and both serum carotenoids and intake frequencies of vegetables and fruits were analyzed using logistic regression modeling for a case-control study; each case (High HbA1c or DM) was matched to two controls (healthy subjects without any history of disease) matched for sex and age (within 3 years). The odds ratio (OR) for high HbA1c was 0.49 (95% confidence interval: 0.29-0.85) on high intake frequency of carrot and pumpkin and the OR for DM was 1.21 (95% Cl: 0.79-1.84). No significant relationships were observed between high HbA1c and intake frequencies of other vegetables and fruits. The ORs on high serum levels of alpha- and beta-carotenes, lycopene, beta-cryptoxanthin and zeaxanthin and lutein were 0.38 (0.22-0.65), 0.35 (0.21-0.59), 0.57 (0.35-0.93), 0.35 (0.20-0.59), and 0.88 (0.54-1.46) for high HbA1c, respectively. In conclusion, intake of vegetables and fruits rich in carotenoids might be a protective factor against hyperglycemia.     

蔬菜类胡萝卜素与矿工肺癌队列研究

目的 :　了解食用蔬菜与云南锡业公司 (云锡 ,YTC)矿工肺癌危险性的关系。方法 :　在食物频率问卷 ( FFQ)重复性和有效性研究的基础上用 χ2 检验、单因素、多因素 Cox回归分析了 7965名 40岁以上云锡矿工肺癌高危人群不同蔬菜摄入量、总蔬菜摄入量和不同类胡萝卜素摄入量与其发生肺癌相对危险性的关系。结果 :　摄入不同水平蔬菜、类胡萝卜素的矿工 ,肺癌发病率不同 ;其中总蔬菜、根茎类、葱属蔬菜、芹菜、十字花科蔬菜、薯芋类、苦瓜等浅色瓜、豆芽菜、β-胡萝卜素、α-胡萝卜素、叶黄素和玉米黄质等在不同摄入水平时云锡矿工肺癌发病率有显著性差异( P<0 .0 5 ) ;总蔬菜、根茎类、葱属蔬菜、芹菜、十字花科蔬菜、薯芋类、苦瓜等浅色瓜、β-胡萝卜素、α-胡萝卜素与肺癌相对危险性呈负相关 ( RR<1 ,P<0 .0 5 ) ;经调整年龄、工龄、吸烟后 ,根茎类、芹菜、十字花科蔬菜、薯芋类、β-胡萝卜素、α-胡萝卜素仍显示与矿工肺癌危险性呈负相关 ( RR=0 .5～ 0 .75 ,P<0 .0 5 )。结论 :　蔬菜尤其是芹菜、根茎类、十字花科蔬菜、薯芋类、β-胡萝卜素、α-胡萝卜素对云锡矿工肺癌确有一定预防作用     

Low Intake of Vegetables and Fruits and Risk of Colorectal Cancer: The Japan Collaborative Cohort Study

Background

The evidence for an association between low intake of vegetables and fruits and increased colorectal cancer risk is inconclusive. Evaluating the colorectal cancer risk associated with continued low intake is important.

Methods

We used data of 45 516 and 14 549 subjects aged 40–79 years obtained in the baseline and interim surveys, respectively, from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study). The intake frequency of vegetables and fruits as assessed by a self-administered questionnaire was classified into tertiles of low, middle, and high groups, and the low group was subdivided into 2 equal groups (lower low and higher low groups). Colorectal cancer incidence determined from follow-up was used. Cox’s proportional hazard model was employed to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for covariates.

Results

During 598 605 person-years of subject follow-up after baseline, we identified 806 colorectal cancer cases. HRs for the lower low versus the middle and high intake frequencies of vegetables and fruits at baseline were 0.95 (95% CI 0.77–1.16) and 1.08 (95% CI 0.90–1.29), respectively. During 125 980 person-years of subject follow-up after the interim survey, 197 colorectal cancer cases were identified. HRs for the low versus middle and high intake frequencies of vegetables and fruits in both baseline and interim surveys were 0.91 (95% CI 0.61–1.37) and 0.87 (95% CI 0.59–1.27), respectively.

Conclusions

Our results suggest that low intake and continued low intake of vegetables and fruits are not strongly associated with colorectal cancer risk.Key words: colorectal cancer, vegetables, fruits, food intake, epidemiology