Fruit and Vegetable Intake Assessed by Food Frequency Questionnaire and Plasma Carotenoids: A Validation Study in Adults

Dietary validation studies of self-reported fruit and vegetable intake should ideally include measurement of plasma biomarkers of intake. The aim was to conduct a validation study of self-reported fruit and vegetable intakes in adults, using the Australian Eating Survey (AES) food frequency questionnaire (FFQ), against a range of plasma carotenoids. Dietary intakes were assessed using the semi-quantitative 120 item AES FFQ. Fasting plasma carotenoids (α- and β-carotene, lutein/zeaxanthin, lycopene and cryptoxanthin) were assessed using high performance liquid chromatography in a sample of 38 adult volunteers (66% female). Significant positive correlations were found between FFQ and plasma carotenoids for α-carotene, β-carotene and lutein/zeaxanthin (52%, 47%, 26%, p < 0.001, 0.003, 0.041; respectively) and relationships between plasma carotenoids (except lycopene) and weight status metrics (BMI, waist circumference, fat mass) were negative and highly significant. The results of the current study demonstrate that carotenoid intakes as assessed by the AES FFQ are significantly related to plasma concentrations of α-carotene, β-carotene and lutein/zeaxanthin, the carotenoids commonly found in fruit and vegetables. Lower levels of all plasma carotenoids, except lycopene, were found in individuals with higher BMI. We conclude that the AES can be used to measure fruit and vegetable intakes with confidence.     

Hispanic and non-Hispanic white elders from Massachusetts have different patterns of carotenoid intake and plasma concentrations

Carotenoids have been linked with protective roles against diseases associated with aging, including cancer, cardiovascular disease, cataracts, and age-related macular degeneration. With data from a semiquantitative, validated FFQ, we examined carotenoid intake of 340 Puerto Ricans, 98 Dominicans, and 146 non-Hispanic whites (>60 y old) in Massachusetts. Compared with non-Hispanic white men, Hispanic men reported a higher intake of lycopene and lower intakes of alpha-carotene, lutein + zeaxanthin, beta-carotene (from diet only), and total beta-carotene (diet and supplements) (P < 0.001). Hispanic women reported higher intakes of beta-cryptoxanthin and lycopene but lower intakes of lutein + zeaxanthin (P < 0.001) than non-Hispanic white women. The frequency of consumption of fruit and vegetables was higher among Hispanic women, relative to non-Hispanic white women (P < 0.05). Plasma concentrations of alpha-carotene and lycopene were higher in Hispanic than in non-Hispanic white men and women. For both ethnic groups, higher intakes of carotenoids were associated with higher plasma concentrations of the respective carotenoids, except for lycopene (Hispanics) and lutein + zeaxanthin (non-Hispanic whites). Food sources contributing most to total intakes differed among the groups. The major sources of alpha- and beta-carotene were carrots for non-Hispanic whites and winter squash for Hispanics. The major source of lycopene was cooked tomato products for Hispanics, and pasta dishes for non-Hispanic whites. Traditional foods such as beans and plantains were also important contributors of carotenoids for Hispanics. Because of the potential importance of carotenoids as protective factors against chronic diseases, more attention to food-related practices associated with carotenoid intake in differing population groups is warranted.     

Carotenoid intakes, assessed by dietary questionnaire, are associated with plasma carotenoid concentrations in an elderly population

High intakes of fruits and vegetables and of carotenoids are associated with a lower risk for a variety of chronic diseases. It is therefore important to test the validity of dietary questionnaires that assess these intakes. We compared intakes of five carotenoids, as calculated from responses to the Willett 126-item food-frequency questionnaire, with corresponding biochemical measures. Subjects included 346 women and 201 men, aged 67-93 y, in the Framingham Heart Study. Unadjusted correlations were higher among women than men as follows: alpha-carotene 0.33 and 0.18, beta-carotene, 0.36 and 0.25; beta-cryptoxanthin, 0.44 and 0.32; lycopene, 0.35 and 0.21; and lutein + zeaxanthin, 0.27 and 0.10, respectively. Adjustment for age, energy intake, body mass index (BMI, kg/m2), plasma cholesterol concentrations and smoking reduced the gender differences, respectively, to the following: alpha-carotene 0.30 and 0.28; beta-carotene, 0.34 and 0.31; beta-cryptoxanthin, 0.45 and 0.36; lycopene, 0.36 and 0.31; and lutein + zeaxanthin, 0.24 and 0.14. Plots of adjusted mean plasma carotenoid concentration by quintile of respective carotenoid intake show apparent greater responsiveness among women, compared with men, to dietary intake of alpha- and beta-carotene and beta-cryptoxanthin, but similar blood-diet relationships for lycopene and lutein + zeaxanthin. Reported daily intake of fruits and vegetables correlated most strongly with plasma beta-cryptoxanthin and beta-carotene among women and with plasma alpha- and beta-carotene among men. With the exception of lutein + zeaxanthin, this dietary questionnaire does provide reasonable rankings of carotenoid status among elderly subjects, with the strongest correlations for beta-cryptoxanthin. Appropriate adjustment of confounders is necessary to clarify these associations among men.     

Plasma carotenoids as biomarkers of intake of fruits and vegetables: individual-level correlations in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVE: The aim in this study was to assess the association between individual plasma carotenoid levels (alpha-carotene, beta-carotene, lycopene, beta-cryptoxanthin, lutein, zeaxanthin) and fruit and vegetable intakes recorded by a calibrated food questionnaire (FQ) and 24-h dietary recall records (24HDR) in nine different European countries with diverse populations and widely varying intakes of plant foods. DESIGN: A stratified random subsample of 3089 men and women from nine countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC), who had provided blood samples and dietary and other lifestyle information between 1992 and 2000, were included. RESULTS: beta-Cryptoxanthin was most strongly correlated with total fruits (FQ r = 0.52, 24HDR r = 0.39), lycopene with tomato and tomato products (FQ r = 0.38, 24HDR r = 0.25), and alpha-carotene with intake of root vegetables (r = 0.39) and of total carrots (r = 0.38) for FQ only. Based on diet measured by FQ and adjusting for possible confounding by body mass index (BMI), age, gender, smoking status, alcohol intake, and energy intake, the strongest predictors of individual plasma carotenoid levels were fruits (R(partial)(2) = 17.2%) for beta-cryptoxanthin, total carrots ((partial)(2) = 13.4%) and root vegetables (R(partial)(2) = 13.3%) for alpha-carotene, and tomato products (R(partial)(2) = 13.8%) for lycopene. For 24HDR, the highest R(partial)(2) was for fruits in relation to beta-cryptoxanthin (7.9%). CONCLUSIONS: Intakes of specific fruits and vegetables as measured by food questionnaires are good predictors of certain individual plasma carotenoid levels in our multicentre European study. At individual subject levels, FQ measurements of fruits, root vegetables and carrots, and tomato products are, respectively, good predictors of beta-cryptoxanthin, alpha-carotene, and lycopene in plasma.     

Fruits and vegetables increase plasma carotenoids and vitamins and decrease homocysteine in humans

Observational epidemiologic studies have shown that a high consumption of fruits and vegetables is associated with a decreased risk of chronic diseases. Little is known about the bioavailability of constituents from vegetables and fruits and the effect of these constituents on markers for disease risk. Currently, the recommendation is to increase intake of a mix of fruits and vegetables ("five a day"). We investigated the effect of this recommendation on plasma carotenoids, vitamins and homocysteine concentrations in a 4-wk dietary controlled, parallel intervention study. Male and female volunteers (n = 47) were allocated randomly to either a daily 500-g fruit and vegetable ("high") diet or a 100-g fruit and vegetable ("low") diet. Analyzed total carotenoid, vitamin C and folate concentrations of the daily high diet were 13.3 mg, 173 mg and 228.1 microg, respectively. The daily low diet contained 2.9 mg carotenoids, 65 mg vitamin C and 131.1 microg folate. Differences in final plasma levels between the high and low group were as follows: lutein, 46% [95% confidence interval (CI) 28-64]; beta-cryptoxanthin, 128% (98-159); lycopene, 22% (8-37); alpha-carotene, 121% (94-149); beta-carotene, 45% (28-62); and vitamin C, 64% (51-77) (P < 0.05). The high group had an 11% (-18 to -4) lower final plasma homocysteine and a 15% (0.8-30) higher plasma folate concentration compared with the low group (P < 0.05). This is the first trial to show that a mix of fruits and vegetables, with a moderate folate content, decreases plasma homocysteine concentrations in humans.     

Plasma carotenoids as biomarkers of intake of fruits and vegetables: ecological-level correlations in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVE: The aim of this study was to assess the ability of a single 24-h dietary recall (24HDR) and food questionnaires (FQ) to predict plasma carotenoid levels at the ecological level by assessing the relationship between mean plasma carotenoid levels and mean intake of fruit and vegetables measured by 24HDR and FQ across 16 European regions. DESIGN: A random subsample of 3089 subjects was included, stratified by age and gender. They provided blood samples and dietary information between 1992 and 2000 as part of the European Prospective Investigation into Cancer and Nutrition. RESULTS: Using Spearman's correlation coefficients, the correlations between mean regional 24HDR fruit and vegetable variables and corresponding mean plasma carotenoid levels were generally higher than the correlations using FQ means. The highest correlation was between the 24HDR citrus fruit variable and beta-cryptoxanthin (r = 0.90). For 24HDR, total fruits and vegetables were highly correlated with lutein, zeaxanthin, and beta-cryptoxanthin (r = 0.83-0.87), while vegetables were more closely related with lutein (r = 0.69) and zeaxanthin (r = 0.68), and fruits correlated with zeaxanthin (r = 0.87) and beta-cryptoxanthin (r = 0.84). Root vegetables (r = 0.81) and total carrots (r = 0.71) were well correlated with alpha-carotene. In the multivariate models adjusting for age, body mass index, and season, and using observations of means stratified by sex and region, the association was generally higher for 24HDR compared to FQ. CONCLUSION: Mean regional intakes of fruits and vegetables in several European countries were closely correlated with corresponding mean plasma levels of individual carotenoids. Fruits and vegetables measured by 24HDR were generally better able to predict plasma carotenoids at the ecological level.     

Six carotenoids in plasma used to assess recommended intake of fruits and vegetables in a controlled feeding study

BACKGROUND: There is a need for objective and universally applicable biomarkers for the intake of foods believed to affect human health. OBJECTIVE: The purpose of this feeding study was to test whether plasma concentrations of carotenoids could be used to distinguish recommended consumption of mixed fruits and vegetables (five a day) from the current national intake of fruits and vegetables (two a day). DESIGN: A strict crossover design was chosen to correct for observed interindividual variations in carotenoid response. A total of 40 healthy subjects were included in the study. After 1 week run-in period with no fruits and vegetables in the diet, one group was given two portions (300 g) of fruits and vegetables daily, while another group was given five portions (750 g) for 14 days. Following a 2 week wash-out period and 1 week run-in, the regimens were switched between the groups. Fruits and vegetables were combined to match a typical Norwegian diet. RESULTS: Enhanced intake from two to five portions of mixed fruits and vegetables increased plasma concentrations of alpha-carotene (P=0.033) and lutein (P=0.051) in a crossover analysis. Analysis of data in the parallel part of the study revealed differences between the high and low intake for plasma concentrations of alpha-carotene (P=0.013) and beta-carotene (P=0.016). A trend was also evident for plasma concentrations of lycopene (P=0.057) and lutein (P=0.076) in the parallel analysis. No effect of high vs low intake of fruits and vegetables was observed for plasma concentrations of beta-cryptoxanthin, zeaxanthin, cholesterol and triacylglycerols. CONCLUSION: The study indicates that plasma concentration of alpha-carotene, beta-carotene and lutein may be used to assess changes of fruit and vegetable intake corresponding to an increase from the present national intake in Norway to the recommended amount of five portions of fruits and vegetables daily. SPONSORSHIP: Norwegian Research Council, National Nutrition Council, Throne Holst Foundation for Nutrition Research and Freia Chokoladefabriks Medisinske Fond.     

Serum carotenoids and breast cancer.

The consumption of vegetables and fruit may protect against many types of cancer, but research evidence is not compelling for breast cancer. Carotenoids are pigments that are present in most plants and have known antioxidant properties. Blood concentrations of carotenoids have been proposed as integrated biochemical markers of vegetable, fruit, and synthetic supplements consumed. In a case-control study (270 cases, 270 controls) nested within a cohort in New York during 1985-1994, the carotenoids lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, and beta-carotene were measured in archived serum samples using liquid chromatography. There was an evident increase in the risk of breast cancer for decreasing beta-carotene, lutein, alpha-carotene, and beta-cryptoxanthin. The risk of breast cancer approximately doubled among subjects with blood levels of beta-carotene at the lowest quartile, as compared with those at the highest quartile (odds ratio = 2.21; 95% confidence interval (CI): 1.29, 3.79). The risk associated with the other carotenoids was similar, varying between 2.08 (95% CI: 1.11, 3.90) for lutein and 1.68 (95% CI: 0.99, 2.86) for beta-cryptoxanthin. The odds ratio for the lower quartile of total carotenoids was 2.31 (95% CI: 1.35, 3.96). These observations offer evidence that a low intake of carotenoids, through poor diet and/or lack of vitamin supplementation, may be associated with increased risk of breast cancer and may have public health relevance for people with markedly low intakes.     

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.     

Plasma carotenoids are biomarkers of long-term high vegetable intake in women with breast cancer

We investigated predictors of change in plasma carotenoids from baseline to 3 y and examined plasma carotenoid concentrations at 1 and 3 y in response to a high vegetable diet. Participants were 56 women diagnosed with breast cancer and enrolled in a randomized feasibility study for a trial examining the effect of a diet high in vegetables and fruits on the risk of breast cancer recurrence. Independent t test analysis revealed that the intervention group had significantly higher vegetable and fruit servings and fiber at 12 mo and significantly higher vegetable servings at 36 mo compared with the control group (P < 0.05). Energy intake from fat was significantly lower in the intervention group at 12 and 36 mo. The intervention group had significantly higher consumption of beta-carotene, alpha-carotene, lutein and beta-cryptoxanthin at 12 mo (P < 0.05). beta-Carotene, alpha-carotene and lutein intakes also were significantly higher at 36 mo (P < 0.05). At 36 mo, the intervention group had significantly higher plasma concentrations of alpha-carotene and beta-carotene compared with the control group. Repeated-measures ANOVA revealed that the intervention group had significantly increased (P < 0.05 with Bonferroni correction) plasma beta-carotene, alpha-carotene, lutein and lycopene concentrations at 12 and 36 mo compared with baseline. Baseline carotenoid concentrations were significantly inversely predictive (P < 0.05) of plasma carotenoid change. In addition, change in body mass index (BMI) and plasma cholesterol concentrations were predictive of plasma carotenoid change from baseline to 3 y. Results of this study demonstrate that change in plasma carotenoid concentrations is associated with change in BMI, change in plasma cholesterol and baseline carotenoid concentrations. Plasma carotenoid response can be an indicator of long-term high vegetable intake for women at risk of breast cancer recurrence.     

Validation of a food frequency questionnaire to assess the consumption of carotenoids, fruits and vegetables among adolescents: the method of triads

The aim of this study was to validate the intake of carotenoids, fruits and vegetables estimated by the Food Frequency Questionnaire for Adolescents (FFQA) using the method of triads. Blood samples were collected from 80 elementary school adolescents to assess serum levels of β-carotene. Partial correlation coefficients (r) were calculated between an estimated intake of carotenoids, fruits and vegetables and the serum levels of β-carotene. Validity coefficients were calculated using the method of triads. With the exception of carotenoids, partial r from the food frequency questionnaire (FFQ) were greater than those of the 24-hour recall (24hR). The fruit/vegetable group showed the highest partial r for the FFQ (r = 0.235) and the 24hR (r = 0.137). The highest validity coefficient was obtained for the vegetable group, as assessed by the FFQ (r = 0.873). On average, the validity coefficient values for the FFQ were greater than those obtained for the 24hR or the β-carotene serum levels. The FFQA is an accurate tool for estimating the intake of carotenoids, fruits and vegetables in this population group.     

Acculturation in the United States is associated with lower serum carotenoid levels: Third National Health and Nutrition Examination Survey

This study examined the association of acculturation in the United States and serum carotenoid levels. The design was a cross-sectional, nationally representative survey of 16,539 participants, 17 years of age and older, from the Third National Health and Nutrition Examination Survey (NHANES III). The main outcome measures were serum levels of alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, lycopene, and total carotenoids. Multivariate linear regression was used to model the association of serum carotenoids and country of birth, language of interview, and years in the United States. Adjustments were made for age, sex, years of education, race/ethnicity, body mass index, alcohol use, physical activity, serum cotinine, serum cholesterol, and vitamin/mineral usage. Individuals born in the United States who speak English had the lowest levels of carotenoids, and individuals born in Mexico had the highest levels of carotenoids, with the exception of lycopene. Years of residence in the United States was associated with lower alpha-carotene (4.18 vs 1.51), beta-carotene (20.21 vs 14.87), beta-cryptoxanthin (12.51 vs 8.95), lutein/zeaxanthin (25.15 vs 18.03), and total carotenoids (88.79 vs 75.44). Years residence in the United States was positively associated with higher lycopene levels (26.69 vs 32.03). Acculturation in the United States was associated with lower fruit and vegetable intake, as measured by serum carotenoid levels.     

Bioavailability of lutein from vegetables is 5 times higher than that of beta-carotene.

BACKGROUND: To gain more insight into the relation between vegetable consumption and the risk of chronic diseases, it is important to determine the bioavailability of carotenoids from vegetables and the effect of vegetable consumption on selected biomarkers of chronic diseases. OBJECTIVE: To assess the bioavailability of beta-carotene and lutein from vegetables and the effect of increased vegetable consumption on the ex vivo oxidizability of LDL. DESIGN: Over 4 wk, 22 healthy adult subjects consumed a high-vegetable diet (490 g/d), 22 consumed a low-vegetable diet (130 g/d), and 10 consumed a low-vegetable diet supplemented with pure beta-carotene (6 mg/d) and lutein (9 mg/d). RESULTS: Plasma concentrations of vitamin C and carotenoids (ie, alpha-carotene, beta-carotene, lutein, zeaxanthin, and beta-cryptoxanthin) were significantly higher after the high-vegetable diet than after the low-vegetable diet. In addition to an increase in plasma beta-carotene and lutein, the pure carotenoid-supplemented diet induced a significant decrease in plasma lycopene concentration of -0.11 micromol/L (95% CI: -0.21, -0.0061). The responses of plasma beta-carotene and lutein to the high-vegetable diet were 14% and 67%, respectively, of those to the pure carotenoid- supplemented diet. Conversion of beta-carotene to retinol may have attenuated its plasma response compared with that of lutein. There was no significant effect on the resistance of LDL to oxidation ex vivo. CONCLUSIONS: Increased vegetable consumption enhances plasma vitamin C and carotenoid concentrations, but not resistance of LDL to oxidation. The relative bioavailability of lutein from vegetables is higher than that of beta-carotene.     

Plasma carotenoid levels in relation to the Mediterranean diet in Greece

In the context of the Greek segment of the European Prospective Investigation into Cancer and Nutrition (EPIC), we conducted a cross-sectional study to examine the effects of the intake of plant foods central in the traditional Mediterranean diet on plasma levels of alpha-carotene, beta-carotene, lycopene, beta-cryptoxanthin, and lutein-zeaxanthin. Study subjects were a random sample of 45 men and 68 women, aged 30-82 years, from the Greek EPIC cohort of 27,953 volunteers. Linear regression models were fitted, with the carotenoid blood levels as dependent variables. Independent variables were selected food items, as well as body mass index, controlling for energy intake and a set of demographic factors. Body mass index was inversely associated with plasma levels of the studied carotenoids. The association was highly significant for alpha-carotene and beta-carotene, significant for lutein-zeaxanthin, and borderline significant (p approximately 0.07) for lycopene. Tomato intake was significantly positively associated with plasma lycopene, and beta-carotene. Other fruity vegetables and non-fruity vegetables were significantly positively associated, the former with alpha-carotene and the latter with both alpha- and beta-carotene plasma levels. Fruits showed a highly significant positive association with plasma beta-cryptoxanthin, as well as with beta-carotene. No association was found between the intake of olive oil or other added lipids and plasma carotenoids. We conclude that among the studied components of the Mediterranean diet, fruits and vegetables tend to increase levels of some carotenoids, but olive oil has no apparent effect.     

Intake of vitamin A and carotenoids from the Italian population--results of an Italian total diet study

The present study focused on vitamin A and carotenoids (alpha-and beta-carotene, lutein and zeaxanthin, beta-cryptoxanthin, lycopene) daily intake from the Italian total diet. The input of some food groups (cereals, vegetables, fruits, milk and dairy, meat and meat products, fish) most responsible for major and minor contributions to the daily intake of these molecules was evaluated. Furthermore the contribution to the dietary intake of beta-carotene and lutein of the most consumed vegetables in the market basket of the Italian total diet (beets, brassica vegetables, carrots, chicory, courgette (zucchini), green beans, lettuce, peas, pepper, spinach, tomatoes) was also investigated. Vitamin A daily intake was 855 mg/person/day. The vegetables food group made the greatest contribution (37%), followed by the meat and meat products food group (23%). The Italian total diet provided 14.3 mg/person/day of carotenoids; lycopene was the highest (7.4 mg/day), followed by lutein + zeaxanthin (4 mg/day), beta-carotene (2.6 mg/day), alpha-carotene (0.15 mg/day), and beta-cryptoxanthin (0.17 mg/day). Carrots and tomatoes were the main sources of beta-carotene in the diet, otherwise the daily consumption of leafy vegetables (spinach, beets, lettuce) made the main contribution to lutein + zeaxanthin daily intake.     

Influence of habitual diet on antioxidant status: a study in a population of vegetarians and omnivores

BACKGROUND: Antioxidant status can be used as a biomarker to assess chronic disease risk and diet can modulate antioxidant defence. OBJECTIVE: To examine effects of vegetarian diet and variations in the habitual intakes of foods and nutrients on blood antioxidants. SUBJECTS AND SETTING: Thirty-one vegetarians (including six vegans) and 58 omnivores, non-smokers, in Northern Ireland. DESIGN: A diet history method was used to assess habitual diet. Antioxidant vitamins, carotenoids, uric acid, zinc- and ferric-reducing ability of plasma (FRAP) were measured in fasting plasma and activities of glutathione peroxidase (GPX), superoxide dismutase (SOD) and glutathione S-transferase (GST) and level of reduced glutathione (GSH) were measured in erythrocytes. RESULTS: Vegetarians had approximately 15% higher levels of plasma carotenoids compared with omnivores, including lutein (P< or =0.05), alpha-cryptoxanthin P< or =0.05), lycopene (NS), alpha-carotene (NS) and beta-carotene (NS). The levels/activities of all other antioxidants measured were similar between vegetarians and omnivores. Total intake of fruits, vegetables and fruit juices was positively associated with plasma levels of several carotenoids and vitamin C. Intake of vegetables was positively associated with plasma lutein, alpha-cryptoxanthin, alpha-carotene and beta-carotene, whereas intake of fruits was positively associated with plasma beta-cryptoxanthin. Intake of tea and wine was positively associated with FRAP value, whereas intake of herbal tea associated positively with plasma vitamin C. Intakes of meat and fish were positively associated with plasma uric acid and FRAP value. CONCLUSIONS: The overall antioxidant status was similar between vegetarians and omnivores. Good correlations were found between intakes of carotenoids and their respective status in blood.     

An approach to estimate between- and within-group correlation coefficients in multicenter studies: plasma carotenoids as biomarkers of intake of fruits and vegetables

In a multicenter study, the overall correlation between two variables can be broken down into a within- and a between-group correlation reflecting associations at the individual and aggregate levels, respectively. A random-effects model is used to estimate variance components of nutrition-related variables and the within- and between-group correlation coefficients. Using data from the European Prospective Investigation into Cancer and Nutrition (EPIC), the authors analyzed the association between levels of three plasma carotenoids (alpha-carotene, beta-cryptoxanthin, and lycopene) and dietary intake of three items (total fruits, carrots, and tomatoes), assessed through dietary questionnaire and single 24-hour dietary recall measurements, in a cross-sectional study involving 3,089 subjects from nine European countries. Intraclass correlation coefficients were 0.178 for alpha-carotene, 0.216 for beta-cryptoxanthin, and 0.299 for lycopene. The between-group correlation coefficients were higher than the within-group coefficients for all three carotenoids. For beta-cryptoxanthin and fruit intake, the between-group versus the within-group correlations were 0.78 and 0.26 for the dietary questionnaire and 0.85 and 0.19 for the 24-hour dietary recall. Results indicate that variability of exposure is driven mainly by the individual compared with the aggregate variation and that biomarker levels perform fairly accurately in discriminating population-level consumption of fruits and vegetables.     

A European carotenoid database to assess carotenoid intakes and its use in a five-country comparative study

A food frequency questionnaire (FFQ) and carotenoid database with information on alpha- and beta-carotene, lutein, lycopene and beta-cryptoxanthin was prepared and used to compare the carotenoid intakes in five European countries: UK, Republic of Ireland, Spain, France and The Netherlands. Eighty, age- (25-45 years) and sex-matched volunteers were recruited in each of the five countries. A FFQ and carotenoid database was prepared of the most commonly consumed carotenoid rich foods in the participating countries and the information was used to calculate frequency and intake of carotenoid-rich foods. The median total carotenoid intake based on the sum of the five carotenoids, was significantly higher (P < 0.05) in France (16.1 mg/day) and lower in Spain (9.5 mg/day,) than the other countries, where the average intake was approximately 14 mg/day. Comparison of dietary source of carotenoids showed that carrots were the major source of beta-carotene in all countries except Spain where spinach was most important. Likewise, carrots were also the main source of alpha-carotene. Tomato or tomato products, were the major source of lycopene. Lutein was mainly obtained from peas in Republic of Ireland and the UK, however, spinach was found to be the major source in other countries. In all countries, beta-cryptoxanthin was primarily obtained from citrus fruit. Comparing the data with that from specific European country studies suggests that the FFQ and carotenoid database described in the present paper can be used for comparative dietary intake studies within Europe. The results show that within Europe there are differences in the specific intake of some carotenoids which are related to different foods consumed by people in different countries.     

Telephone counseling intervention increases intakes of micronutrient- and phytochemical-rich vegetables, fruit and fiber in breast cancer survivors

Although a large body of evidence suggests that diet may play an important role in cancer prevention, randomized controlled trials reported to date have not achieved sufficient increases in protective micronutrients and phytochemicals to adequately test the hypothesis that diet can reduce cancer risk. The Women's Healthy Eating and Living (WHEL) Study, a randomized controlled trial of the role diet modification may play in future breast cancer events, introduced an innovative theory-based telephone counseling intervention to teach participants to consume a high fiber, low fat diet emphasizing vegetables and fruits rich in carotenoids and other potentially protective phytochemicals. This report examines the baseline to 12-mo changes in dietary intakes of 2970 participants, assessed through 24-h recalls and validated with plasma carotenoid concentrations. At 12 mo, the intervention group reported a significantly increased daily vegetable intake (+vegetable juice) of 7.1 servings (+82%) and fruit intake of 3.9 servings (+18%). Fiber intake increased from 3.04 to 4.16 g/(MJ. d), whereas energy from fat decreased significantly from 28.6 to 23.7%. Plasma carotenoid concentrations increased significantly, i.e., alpha-carotene (+223%); beta-carotene (+87%); lutein (+29%); and lycopene (+17%). In the comparison group, dietary intake and plasma carotenoid concentrations were essentially identical to those of the intervention group at baseline and were unchanged at 12 mo. The WHEL Study showed that a telephone counseling intervention can achieve major increases in micronutrient- and phytochemical-rich vegetables, fruit and fiber intakes, enabling an investigation of the potential cancer preventive effects of these food components.     

Serum concentrations of carotenoids and vitamins A, E, and C in control subjects from five European countries

High intakes of fruits and vegetables, or high circulating levels of their biomarkers (carotenoids, vitamins C and E), have been associated with a relatively low incidence of cardiovascular disease, cataract and cancer. Exposure to a high fruit and vegetable diet increases antioxidant concentrations in blood and body tissues, and potentially protects against oxidative damage to cells and tissues. This paper describes blood concentrations of carotenoids, tocopherols, ascorbic acid and retinol in well-defined groups of healthy, non-smokers, aged 25-45 years, 175 men and 174 women from five European countries (France, UK (Northern Ireland), Republic of Ireland, The Netherlands and Spain). Analysis was centralised and performed within 18 months. Within-gender, vitamin C showed no significant differences between centres. Females in France, Republic of Ireland and Spain had significantly higher plasma vitamin C concentrations than their male counterparts. Serum retinol and alpha-tocopherol levels were similar between centres, but gamma-tocopherol showed a great variability being the lowest in Spain and France, and the highest in The Netherlands. The provitamin A: non-provitamin A carotenoid ratio was similar among countries, whereas the xanthophylls (lutein, zeaxanthin, beta-cryptoxanthin) to carotenes (alpha-carotene, beta-carotene, lycopene) ratio was double in southern (Spain) compared to the northern areas (Northern Ireland and Republic of Ireland). Serum concentrations of lutein and zeaxanthin were highest in France and Spain; beta-cryptoxanthin was highest in Spain and The Netherlands; trans-lycopene tended to be highest in Irish males and lowest in Spanish males; alpha-carotene and beta-carotene were higher in the French volunteers. Due to the study design, the concentrations of carotenoids and vitamins A, C and E represent physiological ranges achievable by dietary means and may be considered as 'reference values' in serum of healthy, non-smoking middle-aged subjects from five European countries. The results suggest that lutein (and zeaxanthin), beta-cryptoxanthin, total xanthophylls and gamma-tocopherol (and alpha- : gamma-tocopherol) may be important markers related to the healthy or protective effects of the Mediterranean-like diet.