Development of a food composition database for the estimation of dietary intakes of glucosinolates, the biologically active constituents of cruciferous vegetables

Evidence indicates that cruciferous vegetables are protective against a range of cancers with glucosinolates and their breakdown products considered the biologically active constituents. To date, epidemiological studies have not investigated the intakes of these constituents due to a lack of food composition databases. The aim of the present study was to develop a database for the glucosinolate content of cruciferous vegetables that can be used to quantify dietary exposure for use in epidemiological studies of diet-disease relationships. Published food composition data sources for the glucosinolate content of cruciferous vegetables were identified and assessed for data quality using established criteria. Adequate data for the total glucosinolate content were available from eighteen published studies providing 140 estimates for forty-two items. The highest glucosinolate values were for cress (389 mg/100 g) while the lowest values were for Pe-tsai chinese cabbage (20 mg/100 g). There is considerable variation in the values reported for the same vegetable by different studies, with a median difference between the minimum and maximum values of 5.8-fold. Limited analysis of cooked cruciferous vegetables has been conducted; however, the available data show that average losses during cooking are approximately 36 %. This is the first attempt to collate the available literature on the glucosinolate content of cruciferous vegetables. These data will allow quantification of intakes of the glucosinolates, which can be used in epidemiological studies to investigate the role of cruciferous vegetables in cancer aetiology and prevention.     

Cruciferous vegetables and colo-rectal cancer

Cruciferous vegetables have been studied extensively for their chemoprotective effects. Although they contain many bioactive compounds, the anti-carcinogenic actions of cruciferous vegetables are commonly attributed to their content of glucosinolates. Glucosinolates are relatively biologically inert but can be hydrolysed to a range of bioactive compounds such as isothiocyanates (ITC) and indoles by the plant-based enzyme myrosinase, or less efficiently by the colonic microflora. A number of mechanisms whereby ITC and indoles may protect against colo-rectal cancer have been identified. In experimental animals cruciferous vegetables have been shown to inhibit chemically-induced colon cancer. However, the results of recent epidemiological cohort studies have been inconsistent and this disparity may reflect a lack of sensitivity of such studies. Possible explanations for the failure of epidemiological studies to detect an effect include: assessment of cruciferous vegetable intake by methods that are subject to large measurement errors; the interaction between diet and genotype has not been considered: the effect that post-harvest treatments may have on biological effects of cruciferous vegetables has not been taken into account.     

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     

Educational attainment and differences in fruit and vegetable consumption among middle-aged adults in the Korean National Health and Nutrition Examination Survey IV

We investigated whether socioeconomic differences affect fruit and vegetable (FV) consumption with respect to total intake and intake of various FV subgroups. Our study included 6667 adults aged 40-64 years who completed a dietary survey in the fourth Korean NHANES (2007-2009). FV intake was estimated from 24-hour recalls and food frequency questionnaires. Differences in FV consumption related to educational attainment were analyzed according to different nutritional categories of FV. Both men and women in the low-education group had the lowest intake of total FV and total fruits, and women also had the lowest intake of total vegetables. Also lowest in this group was consumption of mushrooms and vegetables (excluding kimchi) among men, and cruciferous and allium vegetables (excluding Chinese cabbage and radish) among women, while kimchi consumption was the highest in this group. Additionally, an association between educational level and intake of citrus fruits was evident among men. Adults in the low-education group consumed less carotene-rich FV, red fruit and/or vegetables, and dark-green leafy vegetables, fewer total vegetable dishes, and fewer types of fruit than in other groups. Men in this group had the lowest intake of yellow/orange fruit and/or vegetables, and women consumed the least folate-rich FV. There is a clear association between educational attainment and FV intake with regard to total intake, and to specific nutrients, bioactive compounds, colors, and variety.     

Cruciferous Vegetable Intake and Bulky DNA Damage within Non-Smokers and Former Smokers in the Gen-Air Study (EPIC Cohort)

Epidemiologic studies have indicated that cruciferous vegetables can influence the cancer risk; therefore, we examined with a cross-sectional approach the correlation between the frequent consumption of the total cruciferous vegetables and the formation of bulky DNA damage, a biomarker of carcinogen exposure and cancer risk, in the Gen-Air study within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. DNA damage measurements were performed in the peripheral blood of 696 of those apparently healthy without cancer controls, including 379 never-smokers and 317 former smokers from seven European countries by the ³²P-postlabeling assay. In the Gen-Air controls, the median intake of cruciferous vegetables was 6.16 (IQR 1.16–13.66) g/day, ranging from 0.37 (IQR 0–6.00) g/day in Spain to 11.34 (IQR 6.02–16.07) g/day in the UK. Based on this information, participants were grouped into: (a) high consumers (>20 g/day), (b) medium consumers (3–20 g/day) and (c) low consumers (<3.0 g/day). Overall, low cruciferous vegetable intake was correlated with a greater frequency of bulky DNA lesions, including benzo(a)pyrene, lactone and quinone-adducts and bulky oxidative lesions, in the adjusted models. Conversely, a high versus low intake of cruciferous vegetables was associated with a reduction in DNA damage (up to a 23% change, p = 0.032); this was particularly evident in former smokers (up to a 40% change, p = 0.008). The Generalized Linear Regression models indicated an overall Mean Ratio between the high and the low consumers of 0.78 (95% confidence interval, 0.64–0.97). The current study suggests that a higher intake of cruciferous vegetables is associated with a lower level of bulky DNA adducts and supports the potential for cancer prevention strategies through dietary habit changes aimed at increasing the consumption of cruciferous vegetables.     

Increase in Cruciferous Vegetable Intake in Women Previously Treated for Breast Cancer Participating in a Dietary Intervention Trial

Consumption of cruciferous vegetables has been associated with reduced breast cancer risk mechanistically and in population-based studies, although evidence has been inconsistent. This inconsistency may be related to limitations in quantifying and qualifying cruciferous vegetable exposure using standard instruments for dietary assessment (for example, food-frequency questionnaires, FFQs) or due to low levels of intake demonstrated among U.S. population samples. Cruciferous vegetable intake data are presented from a longitudinal study of a high-vegetable dietary intervention to reduce breast cancer recurrence among breast cancer survivors (n = 1,156; 536 intervention and 620 comparison group subjects). Intake was assessed using repeat administration of an FFQ and cross-sectional administration of a cruciferous vegetable–specific FFQ (CVFFQ). Mean intake in the intervention group assessed using the standard FFQ was 37.7 g/day at baseline and increased to 57.1 g/day at 12 mo (P = 0.0001) and was sustained through 48 mo. Broccoli and cabbage were the most commonly consumed cruciferous vegetables, regardless of the instrument used to assess intake. Differences in intake by group assignment were shown for raw cruciferous vegetables (30.2 g/day vs. 24.6 g/day, assessed using the CVFFQ), suggesting increased exposure to biologically active, cancer-preventive food constituents. These data suggest that this study population will be the first U.S. population sample to provide ample quantity and variety in cruciferous intake to examine whether these vegetables are protective against breast cancer recurrence.     

Non-nutritive biologically active plant components: glucosinolates, their sources and their nutritional significance

Numerous epidemiological studies as well as experimental animal studies suggest that a high intake of cruciferous vegetables is associated with a reduced risk of various forms of cancer. This protective effect has been linked to the high glucosinolate content of these vegetables. Glucosinolate breakdown products, particularly isothiocyanates and nitriles have been shown to modulate carcinogen metabolising enzyme systems, induce cell cycle arrest or apoptosis. The anticancer potential of the different glucosinolate metabolites is diverse and their effect on the above mentioned cellular mechanisms is also affected by the model system employed. Results of in vivo studies with isolated glucosinolates or isothiocyanates compared to those with cruciferous vegetables demonstrate that the chemopreventive effect of cruciferous vegetables is due to combined effect of the different glucosinolate metabolites and the optimal combination of these compounds found in Cruciferae provide the beneficial health effects.     

Usual Cruciferous Vegetable Consumption and Ovarian Cancer: A Case-Control Study

Ovarian cancer is the fifth leading cause of cancer-related deaths among women, primarily due to diagnosis at late stages. Therefore, identification of modifiable risk factors for this disease is warranted. Using the Patient Epidemiology Data System (PEDS), collected from 1981 to 1998 at Roswell Park Cancer Institute, Buffalo, NY, we conducted a hospital-based, case-control analysis of self-reported cruciferous vegetable intake and ovarian cancer among 675 women with primary, incident ovarian cancer, and 1275 without cancer. Cruciferous vegetable intake was queried using a 44-item food frequency questionnaire (FFQ). Odds ratios (OR) and 95% confidence intervals (CI) were estimated with logistic regression, adjusting for age, body mass index (BMI), education, smoking status, parity, family history of ovarian cancer, total fruit consumption, total meat consumption, and total noncruciferous vegetable consumption. We observed a significant inverse association for women with highest vs. lowest intakes of total vegetables (OR = 0.65, 95% CI = 0.46–0.92), cooked cauliflower (OR = 0.82, 95% CI = 0.67–0.99), and cooked greens (OR = 0.63, 95% CI = 0.46–0.86) and an inverse, dose-dependent association between cooked cruciferous vegetables intake and ovarian cancer (for each additional ten servings per month, OR = 0.85, 95% CI = 0.76–0.96). These findings suggest that a diet that includes cruciferous vegetables could be an important modifiable risk factor for ovarian cancer.     

Cruciferous vegetables, the GSTP1 Ile105Val genetic polymorphism, and breast cancer risk

BACKGROUND: Cruciferous vegetables are the primary source of isothiocyanates and other glucosinolate derivatives that are known to induce phase II detoxifying enzymes, including glutathione S-transferases (GSTs). OBJECTIVE: We investigated the independent and combined effects of cruciferous vegetable intake and the GSTP1 Ile(105)Val genetic polymorphism on breast cancer risk. DESIGN: Analyses included 3035 cases and 3037 population controls who were participating in the Shanghai Breast Cancer Study and for whom diet and genetic data were complete (87% of cases and 85% of controls). RESULTS: With the use of multivariate logistic regression, the GSTP1 Val/Val genotype was significantly associated with greater breast cancer risk (OR = 1.50; 95% CI: 1.12, 1.99). The association was significantly greater in premenopausal women (OR = 1.69; 95% CI: 1.17, 2.43) than in postmenopausal women (OR = 1.20; 95% CI: 0.74, 1.92). Total cruciferous vegetable intake was not significantly associated with breast cancer risk, although subjects reporting greater turnip (P for trend < 0.001) and Chinese cabbage (P for trend = 0.049) intakes had a significantly lower postmenopausal breast cancer risk. Women with the GSTP1 Val/Val genotype and low cruciferous vegetable intake had a breast cancer risk 1.74-fold (95% CI: 1.13, 2.67) that of women with the Ile/Ile or Ile/Val genotype. This effect of low cruciferous vegetable intake and the Val/Val genotype was seen predominantly among premenopausal women (OR = 2.08; 95% CI = 1.20, 3.59). CONCLUSIONS: Cruciferous vegetable intake consistent with high isothiocyanate exposure may reduce breast cancer risk. Cruciferous vegetable intake also may ameliorate the effects of the GSTP1 genotype.     

Vegetable and fruit consumption and risks of colon and rectal cancer in a prospective cohort study: The Netherlands Cohort Study on Diet and Cancer

The relation between vegetable and fruit consumption and colorectal cancer risk was comprehensively assessed in the Netherlands Cohort Study on Diet and Cancer using a validated 150-item food frequency questionnaire. After 6.3 years of follow-up (1986-1992), over 1,000 incident cases of colorectal cancer were registered. Using case-cohort analysis, the authors calculated rate ratios and 95% confidence intervals adjusted for age, alcohol intake, and family history of colorectal cancer. For colon cancer, no statistically significant associations with total vegetable intake or total fruit intake were found. However, among women, an inverse association was observed with vegetables and fruits combined (for the highest quintile vs. the lowest, the rate ratio was 0.66 (95% confidence interval: 0.44, 1.01)). Brassica vegetables and cooked leafy vegetables showed inverse associations for both men and women. Among women and, to a lesser extent, among men, inverse associations were stronger for distal colonic tumors than for proximal colonic tumors. For rectal cancer, no statistically significant associations were found for vegetable consumption or fruit consumption or for specific groups of vegetables and fruits; only Brassica vegetables showed a positive association in women. As in other cohort studies, the observed inverse relation between vegetable and fruit consumption and occurrence of colorectal cancer was less strong than relations reported in case-control studies.     

Increase in cruciferous vegetable intake in women previously treated for breast cancer participating in a dietary intervention trial

Consumption of cruciferous vegetables has been associated with reduced breast cancer risk mechanistically and in population-based studies, although evidence has been inconsistent. This inconsistency may be related to limitations in quantifying and qualifying cruciferous vegetable exposure using standard instruments for dietary assessment (for example, food-frequency questionnaires, FFQs) or due to low levels of intake demonstrated among U.S. population samples. Cruciferous vegetable intake data are presented from a longitudinal study of a high-vegetable dietary intervention to reduce breast cancer recurrence among breast cancer survivors (n=1,156; 536 intervention and 620 comparison group subjects). Intake was assessed using repeat administration of an FFQ and cross-sectional administration of a cruciferous vegetable-specific FFQ (CVFFQ). Mean intake in the intervention group assessed using the standard FFQ was 37.7 g/day at baseline and increased to 57.1 g/day at 12 mo (P=0.0001) and was sustained through 48 mo. Broccoli and cabbage were the most commonly consumed cruciferous vegetables, regardless of the instrument used to assess intake. Differences in intake by group assignment were shown for raw cruciferous vegetables (30.2 g/day vs. 24.6 g/day, assessed using the CVFFQ), suggesting increased exposure to biologically active, cancer-preventive food constituents. These data suggest that this study population will be the first U.S. population sample to provide ample quantity and variety in cruciferous intake to examine whether these vegetables are protective against breast cancer recurrence.     

Variation in fruit and vegetable consumption among adults in Britain. An analysis from the dietary and nutritional survey of British adults

OBJECTIVES: Using a national representative sample to examine variation in fruit and vegetable consumption among adults in the UK, with particular reference to consumers with high and low reported intakes. DESIGN: National representative dietary survey using 7-d weighed diet records of men and women aged 16-64 y living in private households in the UK in 1986-1987. SETTING: The UK. SUBJECTS: 1087 men and 1110 women. The sample was selected by a multi-stage random probability design. The response was 70%. Subjects with low energy intake were subsequently excluded. MAIN OUTCOME MEASURES: Food group, nutrient intake, physiological measures socio-economic, demographic and behavioural characteristics. RESULTS: Consumption of fruit and vegetables was estimated. The sample was divided by sex into four quarter groups according to fruit and vegetable consumption. There were significant similarities between quarter groups in fruit and vegetable and other food intake, nutrient intake, physiological measures, and socioeconomic, demographic and behavioural variable. The lowest consumers of fruit and vegetables had a mean intake of 738 g/week (men) and 630 g/week (women), equivalent to 1.3 and 1.1 portion/d, respectively. Conversely, the mean intake of both men women with the highest consumption was 3137 g/week (5.6 portions day). There were more than twice as many adults in the age group 16-24 located in Q1 than in Q4. The Manual social class and those in receipt of benefits were negatively associated with fruit and vegetable consumption. Smokers were significantly associated with low fruit and vegetable intake. Being married was associated with increased fruit and vegetable intake and being single or divorced/separated was associated with low fruit and vegetable intake. Eating home grown produce was associated with high intake. Consumers who lived in London or the South-East were associated with higher fruit and vegetable intake. CONCLUSIONS: The analysis draws attention to the wide variation in reported fruit and vegetable consumption among British adults. High consumers merit further investigation to elucidate practical strategies for increasing fruit and vegetable consumption. Strategies to increase consumption should be targeted at groups most likely to include low consumers of fruits and vegetables. SPONSORSHIP: London School of Hygiene and Tropical Medicine.     

Fruit and vegetable intake in relation to risk of breast cancer in the Black Women's Health Study

The authors prospectively examined the relation of fruit and vegetable intake to breast cancer risk among 51,928 women aged 21-69 years at enrollment in 1995 in the Black Women's Health Study. Dietary intake was assessed by using a validated food frequency questionnaire. Cox proportional hazards models were used to estimate incidence rate ratios and 95% confidence intervals, adjusted for breast cancer risk factors. During 12 years of follow-up, there were 1,268 incident cases of breast cancer. Total fruit, total vegetable, and total fruit and vegetable intakes were not significantly associated with overall risk of breast cancer. However, total vegetable consumption was associated with a decreased risk of estrogen receptor-negative/progesterone receptor-negative breast cancer (incidence rate ratio = 0.57, 95% confidence interval: 0.38, 0.85, for ≥2 servings/day relative to <4/week; P(trend) = 0.02). In addition, there was some evidence of inverse associations with breast cancer risk overall for cruciferous vegetable intake (P(trend) = 0.06) and for carrot intake (P(trend) = 0.02). Study findings suggest that frequent consumption of vegetables is inversely associated with risk of estrogen receptor-negative/progesterone receptor-negative breast cancer, and that specific vegetables may be associated with a decreased risk of breast cancer overall.     

Prospective study of intake of fruit, vegetables, and carotenoids and the risk of adult glioma

BACKGROUND: Nutrients in dietary fruit and vegetables have been hypothesized to lower the risk of glioma by reducing the endogenous formation of N-nitroso compounds. Studies examining fruit and vegetable consumption and brain tumors have relied on case-control study designs, with one exception, and results have been inconsistent. OBJECTIVE: We prospectively examined the relation between consumption of fruit and vegetables (and specifically carotenoids) and the risk of glioma among men and women in 3 large US cohort studies: the Health Professionals Follow-Up Study (HPFS), the Nurses' Health Study I (NHS I), and NHS II. DESIGN: Dietary intake was assessed by food-frequency questionnaires obtained at baseline and updated every 4 y through 2002 (HPFS and NHS I) or 2003 (NHS II). We identified 296 incident adult gliomas during 3 669 589 person-years of follow-up. Cox proportional hazard models were used to estimate incidence rate ratios (RR) and 95% CIs between intake of fruit, vegetables, and carotenoids and glioma risk, with adjustment for age and total caloric intake. RESULTS: Updated average consumption of total fruit and vegetables was not significantly associated with glioma risk in the men and women (pooled multivariate RR in a comparison of the highest with the lowest quintile: 1.12; 95% CI: 0.74, 1.69). Other fruit and vegetable subgroups, individual fruit and vegetables, and 5 major carotenoids were not significantly associated with risk of glioma. CONCLUSION: Our findings suggest that fruit, vegetable, and carotenoid consumption is not likely associated strongly with the risk of adult glioma.     

Knowledge, barriers, and stage of change as correlates of fruit and vegetable consumption among urban and mostly immigrant black men

BACKGROUND: Daily fruit and vegetable consumption in black men is low and has remained relatively unchanged during the past 20 years. OBJECTIVE: To examine awareness of fruit and vegetable recommendations promoted by federal agencies and correlates of fruit and vegetable consumption among an urban and mostly immigrant population of adult black men. DESIGN: A cross-sectional study analyzing baseline data (n=490) from a randomized controlled trial. SETTING: A large health care worker's union. MAIN OUTCOME MEASURES: Knowledge, perceived benefits, stage of readiness, perceived barriers, and daily servings of fruit and vegetable intake. STATISTICAL ANALYSES PERFORMED: One-way analysis of variance and t tests were used to compare fruit and vegetable intake across main study variables. Regression analysis was used to identify independent predictors of fruit and vegetable intake. RESULTS: Fruit and vegetable intake was low (mean was three servings/day). Ninety-four percent were not aware that men should consume at least nine servings of fruits and vegetables daily and 59.8% were not aware that eating a colorful variety is important. In contrast, over half (54.7%) were aware that a single serving is equal to about a handful; 94.1% correctly reported fruit and vegetables as an important source of fiber; 79.6% correctly reported vitamin pills were not a substitute for eating fruits and vegetables; and 94.5% recognized that there are health benefits to eating fruits and vegetables, although identification of specific benefits was minimal. In regression analysis, a greater level of fruit and vegetable consumption was significantly associated with greater knowledge of fruit and vegetable recommendations, lower perceived barriers, and a more advanced stage of change (action vs contemplation/preparation). Perceived health benefits were not associated with fruit and vegetable consumption. CONCLUSIONS: There is a lack of awareness of the current fruit and vegetable recommendations. In addition, men reported fruit and vegetable intakes that were far below national recommendations. Greater efforts are needed to help urban and primarily immigrant black men realize the importance of and recommendations for fruit and vegetable consumption.     

Vegetable intake and long-term survival among middle-aged men in Italy

PURPOSE: To examine prospectively the relationship between vegetable consumption and long-term survival. METHODS: In 1965, a total of 1536 Italian males from two Italian rural cohorts of the Seven Countries Study, aged 45-65 years, were examined. Information on lifestyle and food consumption collected at this visit, and total and cause-specific mortality data collected in 30 years of follow-up were analyzed for the present study. RESULTS: During a period of 30 years, 1096 deaths occurred (308 from coronary heart disease, 325 from cancer, 158 from cerebrovascular disease and 305 from all other causes). The age-adjusted life expectancy for men consuming more than 60 g/day of vegetables was nearly 2 years longer than for men consuming less than 20 g/day. This increase in survival was more striking in smokers than nonsmokers (2.1 vs. a 1 year gain). The association also held for both geographic cohorts, although the pattern of vegetable consumption was very different in the two villages. CONCLUSIONS: The results suggest a positive association between vegetable intake and life expectancy. Vegetable intake may be especially protective for smokers although the biological explanation for such an effect is unclear.     

Sex differences in fruit and vegetable intake in older adults

Fruits and vegetables are important components of a healthy diet, but intakes in most Western countries are well below the recommended five servings a day. Men in particular are eating too little. The aim of this study is to understand the processes underlying this gender difference. Fruit and vegetable intake, nutrition knowledge, taste preferences, attitudes to fruit and vegetable intake, and dieting status, were assessed in a simple questionnaire in 1,024 older adults attending population-based cancer screening across the UK. The results confirmed the pattern of men consuming fewer servings of fruit and vegetables daily than women (2.52 vs 3.47; p<0.01). Fewer men than women knew the current recommendations for fruit and vegetable intake, and fewer were aware of the links between fruit and vegetable consumption and disease prevention. Women rated their liking for vegetables but not fruit higher, and there were no differences in attitudes. Men were less likely to be dieting to lose weight. Multivariate analysis showed that the gender difference in intake was substantially attenuated by controlling for nutrition knowledge. There were no significant attenuating effects of preferences, attitudes or dieting status. These results indicate that men's poorer nutrition knowledge explains a significant part of their lower intake of fruit and vegetables.