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.     

Association of smoking with serum and dietary levels of antioxidants in adults: NHANES III, 1988-1994

OBJECTIVES: This study examined the association of smoking with serum levels and dietary intakes of antioxidants in a nationally representative sample. METHODS: This study classified 7873 apparently healthy adults aged 17 to 50 years from National Health and Nutrition Examination Survey III (NHANES III) data as nonsmokers or as smokers if their serum cotinine levels were either lower than 14 ng/mL or 14 ng/mL or greater, respectively. SUDAAN software was used for the statistical analysis. RESULTS: Smokers of both sexes had significantly (P < .001) lower serum levels of vitamin C, alpha-carotene, beta-carotene, beta-cryptoxanthin, and lutein/zeaxanthin. Reduction in the serum vitamin E, lycopene, and selenium levels in smokers was slight. Smokers also had significantly lower dietary intakes of vitamin C and beta-carotene. A significant (P < .001) inverse relation was found between serum vitamin C and beta-carotene levels and cotinine levels independent of diet effect, and a positive relation (P < .001) was found between serum levels and dietary intakes. CONCLUSIONS: Antioxidants appear to have differing declines in serum levels as a result of reduced dietary intakes and the effects of smoking.     

Vegetables, fruits, and related nutrients and risk of breast cancer: a case-control study in Uruguay

To evaluate whether the protective effect associated with vegetables and fruits in breast cancer could be explained by nutrients and bioactive substances present in these plant foods, we carried out a case-control study in Uruguay including 400 cases and 405 controls. The intake of vegetables, fruits, and related nutrients was estimated with a food frequency questionnaire on 64 food items. This questionnaire allowed the calculation of total energy intake, and nutrients were calorie adjusted by the residuals method. Odds ratios for study variables were estimated by unconditional multiple logistic regression. Total vegetable, total fruit, dietary fiber, vitamin C, vitamin E, lycopene, folate, and total phytosterol intakes were inversely associated with breast cancer risk [4th quartile odds ratio for total vegetable intake = 0.41, 95% confidence interval = 0.26-0.65, p (for trend) = 0.004]. The association with total vegetable intake was not independent of lycopene intake. The results related to vegetable and nutrient intakes are consistent with antioxidant and antiestrogenic effects. This could be mediated, among other nutrients, by dietary fiber and lycopene intake. The role of other unmeasured phytochemicals, correlated with dietary fiber and lycopene intakes, cannot be ruled out.     

Low intakes of vegetables and fruits, especially citrus fruits, lead to inadequate vitamin C intakes among adults

OBJECTIVE: To determine vitamin C intakes among adults and to identify differences in dietary intake associated with vitamin C consumption. DESIGN: This cross-sectional study compared vitamin C intake, nutrient intake, and food group choices of adults with low (<30 mg/d), marginal (30-60 mg/d), and desirable (>60 mg/d) vitamin C intakes. SUBJECTS: Data from 2472 men and 2334 women aged 25-75 y were obtained from the 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII). RESULTS: Overall, 18% of the sample had low vitamin C intakes, 24% had marginal intakes, and 58% had desirable intakes. In addition to consuming less vitamin C, adults with low vitamin C intakes consumed significantly less (P相似文献   

Fruit and vegetable intakes, C-reactive protein, and the metabolic syndrome

BACKGROUND: Limited data on the relation between the risk of the metabolic syndrome and fruit and vegetable intakes and inflammatory marker concentrations are available. OBJECTIVE: We evaluated the relation between fruit and vegetable intakes and C-reactive protein (CRP) concentrations and the prevalence of the metabolic syndrome. DESIGN: Fruit and vegetable intakes were assessed with the use of a validated semiquantitative food-frequency questionnaire in a cross-sectional study of 486 Tehrani female teachers aged 40-60 y. Anthropometric measurements were made and blood pressure was assessed according to standard methods. Fasting blood samples were taken for biochemical measurements. The metabolic syndrome was defined on the basis of the National Cholesterol Education Program Adult Treatment Panel III guidelines. RESULTS: The reported mean daily fruit and vegetable intakes were 228 +/- 79 and 186 +/- 88 g/d, respectively. Both fruit and vegetable intakes were inversely associated with plasma CRP concentrations. After statistical control for age, body mass index, and waist circumference, mean plasma CRP concentrations across increasing quintile categories of fruit intakes were 1.94, 1.79, 1.65, 1.61, and 1.56 mg/L and of vegetable intakes were 2.03, 1.82, 1.58, 1.52, and 1.47 mg/L (P for trend < 0.01 for both). These inverse associations remained significant after additional control for other potential confounding variables and dietary factors. After control for potential confounders, persons in the highest quintile of fruit intake had a 34% (95% CI: 20%, 46%) lower and those in the highest quintile of vegetables intake had a 30% (95% CI: 16%, 39%) lower chance of having the metabolic syndrome than did those in the lowest quintiles. CONCLUSIONS: Higher intakes of fruit and vegetables are associated with a lower risk of the metabolic syndrome; the lower risk may be the result of lower CRP concentrations. These findings support current dietary recommendations to increase daily intakes of fruit and vegetables as a primary preventive measure against cardiovascular disease.     

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.     

Diet, serum insulin-like growth factor-I and IGF-binding protein-3 in European women

OBJECTIVE: The aim of this study was to examine the relationship of diet with serum insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 in women. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: The population are 2109 women who were control subjects in a case-control study of breast cancer nested in the European Prospective Investigation into Cancer and Nutrition. Control subjects were randomly chosen among risk sets consisting of female cohort members alive and free of cancer (except non-melanoma skin cancer) at the time of diagnosis of the index case. Matching criteria were age at enrolment, follow-up time, time of the day of blood collection and study centre. Diet was measured through validated questionnaires. Serum hormone concentrations were measured by enzyme-linked immunosorbent assays. The relationship between serum IGF-I, IGFBP-3, and intake of nutrients and foods was explored by linear regression in models adjusted for energy intake, age, body mass index, smoking, physical activity, centre and laboratory batch. RESULTS: Serum IGF-I levels were positively related to protein intake (P(trend)<0.001), but not related to energy, fat or carbohydrate intake. Positive relationships were observed with the intake of milk (P(trend)=0.007), calcium (P(trend)<0.001), magnesium (P(trend)=0.003), phosphorus (P(trend)<0.001), potassium (P(trend)=0.002), vitamin B6 (P(trend)=0.03), vitamin B2 (P(trend)=0.001) and inverse relationships with vegetables (P(trend)=0.02) and beta-carotene (P(trend)=0.02). IGFBP-3 was not related with most of the nutrients and foods in this study. CONCLUSIONS: In this population, circulating IGF-I is modestly related with the intake of protein and minerals, and with milk and cheese, while IGFBP-3 does not appear to be related with diet.     

Association of diet with serum insulin-like growth factor I in middle-aged and elderly men

BACKGROUND: Insulin-like growth factor I (IGF-I) has been implicated in several chronic diseases, including cancer, heart disease, and osteoporosis. OBJECTIVE: Our aim was to assess whether intakes of total energy, alcohol, vitamins, minerals, and foods rich in protein and minerals (including red meat, fish and seafood, poultry, and milk) are associated with serum IGF-I concentrations in middle-aged and elderly men. DESIGN: We measured serum IGF-I concentrations in 226 free-living healthy men aged 42-76 y. The average of fourteen 24-h dietary telephone interviews performed over 1 y was used to estimate long-term dietary intake. RESULTS: We observed statistically significant positive associations between intakes of protein (P for trend = 0.001) and zinc (P for trend = 0.002) and serum IGF-I concentrations after adjusting for age. The difference in mean IGF-I concentrations for the highest compared with the lowest quintile of intake was approximately 17% (162 microg/L compared with 139 microg/L) for protein and approximately 16% (166 microg/L compared with 143 microg/L) for zinc. Consumption of red meat (P for trend = 0.05) and fish and seafood (P for trend = 0.07) was modestly positively associated with IGF-I concentrations. Other dietary factors were not associated with IGF-I concentrations. CONCLUSION: In this population of healthy well-nourished men, greater dietary intakes of protein, zinc, red meat, and fish and seafood were associated with higher IGF-I concentrations.     

Dietary phylloquinone intake as a potential marker for a heart-healthy dietary pattern in the Framingham Offspring cohort

Abstract Associations were evaluated among self-reported dietary intakes of phylloquinone (vitamin K-1), lifestyle characteristics, and intermediary markers of cardiovascular disease risk in a population-based cohort of men and women. Dietary phylloquinone intakes were assessed by food frequency questionnaire in 1,338 men and 1,603 women (mean age, 54 years) participating in the Framingham Heart Study. Cross-sectional associations with lifestyle characteristics and lipid profiles, including total cholesterol, low-density lipoprotein and high-density lipoprotein cholesterol, and triglyceride concentrations, were estimated across increasing quintile categories of phylloquinone intakes. Participants in the highest quintile category of phylloquinone intake consumed more fruit, vegetables, fish, dietary fiber, and dietary supplements ( P <.001), and consumed less meat and less saturated fat ( P <.001). Higher phylloquinone intakes were also associated with lower triglyceride concentrations ( P <.001). In conclusion, a high phylloquinone intake may be a marker for an overall heart-healthy dietary pattern.     

Selected antioxidants and risk of hormone receptor-defined invasive breast cancers among postmenopausal women in the Women's Health Initiative Observational Study

BACKGROUND: Few studies have evaluated carotenoids and vitamins C and E in association with the risk of breast cancers defined by estrogen receptor (ER) and progesterone receptor (PR) status. OBJECTIVE: We examined the associations between dietary and supplemental intakes of these nutrients and risk of breast cancers jointly defined by both ER and PR status among postmenopausal women. DESIGN: Our investigation was conducted in the Women's Health Initiative Observational Study. After following 84 805 women for an average of 7.6 y, 2879 incident invasive breast cancer cases had been ascertained, of whom 2509 had receptor data. We used Cox proportional hazards models to assess the associations of interest. RESULTS: Dietary alpha-carotene (highest versus lowest quintile: RR = 0.83; 95% CL = 0.70, 0.99; P for trend = 0.019), beta-carotene (highest versus lowest quintile: RR = 0.78; 95% CL = 0.66, 0.94; P for trend = 0.021), and lycopene (highest versus lowest quintile: RR = 0.85; 95% CL = 0.73, 1.00; P for trend = 0.064) were inversely associated with risk of ER+PR+breast cancer, but not with other breast cancer groups jointly defined by ER and PR status. Total or supplemental beta-carotene and dietary intakes of lutein+zeaxanthin and beta-cryptoxanthin were not associated with breast cancers defined by ER and PR status. Vitamin E (regardless of source) and dietary vitamin C were not associated with breast cancer. However, total and supplemental vitamin C intake had weak positive associations with breast cancer overall. CONCLUSION: Dietary intake of certain carotenoids might be differentially associated with risk of invasive breast cancers jointly defined by ER and PR status among postmenopausal women.     

Intake of fruit and vegetables and the risk of ischemic stroke in a cohort of Danish men and women

BACKGROUND: Previous studies have suggested that a high dietary intake of fruit and vegetables is associated with a reduced risk of ischemic stroke. The magnitude of the effect is uncertain, and only one study reported data on the intake of specific fruit and vegetables and the risk of stroke. OBJECTIVE: We examined whether the intake of fruit and vegetables is associated with a reduced risk of ischemic stroke, with particular attention paid to specific fruit and vegetables and subtypes of ischemic stroke. DESIGN: In a prospective cohort study of 54,506 men and women who were included in the Danish Diet, Cancer, and Health study from 1993 to 1997, estimated total intakes of fruit and vegetables (in g/d) were extracted from a semiquantitative food-frequency questionnaire completed at baseline. Data about subjects hospitalized with ischemic stroke were obtained from the Danish National Registry of Patients and were verified later by record reviews. The follow-up for ischemic stroke ended on the date of a first hospital admission for stroke or transient ischemic attack, the date of death or emigration, or the end of the study, whichever came first. RESULTS: We identified 266 cases of ischemic stroke involving hospitalization during 168,388 person-years of follow-up (median follow-up: 3.09 y; range: 0.02-5.10 y). After adjustment for potential confounders, persons in the top quintile of fruit and vegetable intake (median: 673 g/d) had a risk ratio of ischemic stroke of 0.72 (95% CI: 0.47, 1.12) relative to persons in the bottom quintile of intake (median: 147 g/d) (P for trend = 0.04). When comparing the top quintile with the bottom quintile, an inverse association was most evident for fruit intake (risk ratio: 0.60; 95% CI: 0.38, 0.95; P for trend = 0.02). Similar risk estimates were seen for most types of fruit and vegetables, although the risks were significant only for citrus fruit. CONCLUSION: An increased intake of fruit may reduce the risk of ischemic stroke.     

Ascorbate is depleted by smoking and repleted by moderate supplementation: a study in male smokers and nonsmokers with matched dietary antioxidant intakes

BACKGROUND: Lack of reliable dietary data has hampered the ability to effectively distinguish between effects of smoking and diet on plasma antioxidant status. As confirmed by analyses of comprehensive food-frequency questionnaires, the total dietary intakes of fruit and vegetables and of dietary antioxidants were not significantly different between the study groups in the present study, thereby enabling isolation of the effect of smoking. OBJECTIVE: Our objective was to investigate the effect of smoking on plasma antioxidant status by measuring ascorbic acid, alpha-tocopherol, gamma-tocopherol, beta-carotene, and lycopene, and subsequently, to test the effect of a 3-mo dietary supplementation with a moderate-dose vitamin cocktail. DESIGN: In a double-blind, placebo-controlled design, the effect of a vitamin cocktail containing 272 mg vitamin C, 31 mg all-rac-alpha-tocopheryl acetate, and 400 microg folic acid on plasma antioxidants was determined in a population of smokers (n = 37) and nonsmokers (n = 38). The population was selected for a low intake of fruit and vegetables and recruited from the San Francisco Bay area. RESULTS: Only ascorbic acid was significantly depleted by smoking per se (P < 0.01). After the 3-mo supplementation period, ascorbic acid was efficiently repleted in smokers (P < 0.001). Plasma alpha-tocopherol and the ratio of alpha- to gamma-tocopherol increased significantly in both supplemented groups (P < 0.05). CONCLUSIONS: Our data suggest that previous reports of lower concentrations of plasma vitamin E and carotenoids in smokers than in nonsmokers may primarily have been caused by differences in dietary habits between study groups. Plasma ascorbic acid was depleted by smoking and repleted by moderate supplementation.     

Fruit, vegetable, and animal food intake and breast cancer risk by hormone receptor status

The effects of diet on breast cancer are controversial and whether the effects vary with hormone receptor status has not been well investigated. This study evaluated the associations of dietary factors with risk for breast cancer overall and by the hormone receptor status of tumors among Chinese women. The Shanghai Breast Cancer Study, a large, population-based, case-control study, enrolled 3,443 cases and 3,474 controls in 1996-1998 (phase I) and 2002-2005 (phase II); 2676 cases had estrogen receptor (ER) and progesterone receptor (PR) data. Dietary intake was assessed using a validated, quantitative, food frequency questionnaire. Odds ratios (OR) and 95% confidence intervals (95% CI) were derived from multivariate, polychotomous, unconditional logistic regression models. Total vegetable intake was inversely related to breast cancer risk, with an adjusted OR for the highest quintile of 0.80 (95% CI = 0.67-0.95; P trend = 0.02). Reduced risk was also related to high intake of allium vegetables (P trend = 0.01) and fresh legumes (P trend = 0.0008). High intake of citrus fruits and rosaceae fruits were inversely associated with breast cancer risk (P trend = 0.003 and 0.004, respectively), although no consistent association was seen for total fruit intake. Elevated risk was observed for all types of meat and fish intake (all P trend < 0.05), whereas intakes of eggs and milk were associated with a decreased risk of breast cancer (both P trend <0.05). There was little evidence that associations with dietary intakes varied across the 4 tumor subtypes or between ER+/PR+ and ER-/PR- tumors (P for heterogeneity >0.05). Our results suggest that high intake of total vegetables, certain fruits, milk, and eggs may reduce the risk of breast cancer, whereas high consumption of animal-source foods may increase risk. The dietary associations did not appear to vary by ER/PR status.     

Relationships between different types of fruit and vegetable consumption and serum concentrations of antioxidant vitamins

Increased fruit and vegetable consumption has become a health priority in many countries. Therefore, data investigating the influence of different types of fruits and vegetables on serum antioxidant levels would be useful. The objective of the study was to assess the relationship between fruit and vegetable consumption and vitamin serum antioxidant concentrations. Specific fruit and vegetable groups are evaluated. A total of 3521 subjects (1487 men and 2034 women), aged 35-60 years, participating in the SU.VI.MAX cohort were included in this study. Blood samples of participants were analysed for beta-carotene, vitamin C and alpha-tocopherol. Each subject had completed at least six dietary records during the first 2 years of the study. It was found that women had higher mean beta-carotene and vitamin C serum concentrations than men, but lower alpha-tocopherol serum concentrations. Serum beta-carotene and vitamin C concentrations were positively correlated with consumption of both fruit and vegetables, as well as with most of the fruit and vegetable groups tested. These relationships persisted after adjustment for confounding factors. Regression analysis showed a linear dose-response relationship. Root vegetables and citrus fruits were particularly associated with beta-carotene serum status as were citrus fruits for vitamin C. Fruit and vegetable consumption was either not or weakly associated with alpha-tocopherol serum concentrations. These results describe antioxidant serum concentrations according to fruit and vegetable consumption in a large sample and support the findings of previous studies involving a more limited number of subjects.     

Plasma concentrations of carotenoids and vitamin C are better correlated with dietary intake in normal weight than overweight and obese elderly subjects

Carotenoid and vitamin C intakes, assessed by FFQ, have been positively associated with plasma concentrations in different populations. However, the influence of BMI on these associations has not been explored in detail. We explored in a cross-sectional study the relation between dietary carotenoid and vitamin C intakes, using a 135-item FFQ, with their plasma concentrations by BMI categories in 252 men and 293 women, 65 years and older. For men and women combined, significant (P < 0.05) Pearson correlations were observed between energy-adjusted dietary intakes and plasma concentrations (carotenoids adjusted for cholesterol) for: alpha-carotene 0.21, beta-carotene 0.19, lycopene 0.18, beta-cryptoxanthin 0.20 and vitamin C 0.36. Multiple linear regression analyses showed that the intake of carotenoids and vitamin C were significant predictors of their respective plasma concentration (P<0.01), and that BMI was inversely associated with plasma concentration of carotenoids (P< or =0.01) but not with plasma vitamin C. In addition, we observed significant interactions between BMI and the intakes of alpha-carotene and lutein + zeaxanthin, and to a lower extent beta-carotene, suggesting that these intakes in subjects with high BMI were not good predictors of their plasma concentration. The present data suggest that plasma carotenoids and vitamin C may be good markers of dietary intake in elderly subjects, but not so for alpha-carotene, beta-carotene and lutein + zeaxanthin in obese subjects.     

Vegetable consumption and carotenoids in plasma and adipose tissue in Malaga,Spain

OBJECTIVE: To study relationships between habitual dietary intake, adipose tissue concentrations of alpha-carotene, beta-carotene and lycopene, and plasma concentrations of alpha- and beta-carotene. DESIGN: Cross-sectional study including assessment of food habits by a food frequency questionnaire and 48-hour recall and determination of carotenoid concentrations in adipose tissue and plasma. SUBJECTS: 51 women (mean age of 62 years) from the control group of the European Community Multicentre Study on Antioxidants, Myocardial Infarction, and Breast Cancer (EURAMIC), Málaga, Spain. RESULTS: In adipose tissue, beta-carotene was correlated with consumption of green pepper (r = 0.36; p < 0.05) and lycopene with total fruit/vegetable intake (r = 0.28; p < 0.05), green pepper (r = 0.31; p < 0.05), and carrot (r = 0.25; p < 0.10). In plasma, beta-carotene was correlated with total fruit/vegetable intake (r = 0.29; p < 0.10), lettuce (r = 0.34; p < 0.05), tomato (r = 0.26; p < 0.10), and lycopene with total fruit/vegetable intake (r = 0.27; p < 0.10). Age-, BMI- and waist circumference-adjusted regression coefficients for the regression of logn-transformed adipose and plasma concentrations on consumption of specific fruits and vegetables (per 100 g/day) were calculated. In adipose tissue, coefficients were: 1.50 (p < 0.05) for alpha-carotene/carrot; 1.90 (p < 0.10) and 0.51 (p < 0.10) for beta-carotene/green pepper and lettuce; 2.02 (p < 0.05), 1.25 (p < 0.05) and 0.18 (p < 0.05) for lycopene/green pepper, carrot and total fruit/vegetable intake. In plasma, coefficients were 1.14 (p < 0.05) and 0.21 (p < 0.05) for beta-carotene/lettuce and total fruit/vegetable intake. CONCLUSIONS: Consumption of fruit and vegetables could be linked directly to carotenoid concentrations in adipose tissue and plasma. Although associations with individual food items are related to their carotenoid contents, the absorption and distribution of carotenoids needs more attention to improve their usefulness as biomarkers of exposure.     

Vitamin A, retinol, and carotenoids and the risk of gastric cancer: a prospective cohort study

BACKGROUND: Vitamin A may influence gastric carcinogenesis through its essential role in controlling cell proliferation and differentiation. However, epidemiologic studies of vitamin A, retinol (preformed vitamin A), and provitamin A carotenoids in relation to the risk of gastric cancer have documented inconsistent results. OBJECTIVE: The objective of the study was to examine the associations between intakes of vitamin A, retinol, and specific carotenoids and the risk of gastric cancer in a prospective population-based cohort study of Swedish adults. DESIGN: The study cohort consisted of 82 002 Swedish adults aged 45-83 y who had completed a food-frequency questionnaire in 1997. The participants were followed through June 2005. RESULTS: During a mean 7.2-y follow-up, 139 incident cases of gastric cancer were diagnosed. High intakes of vitamin A and retinol from foods only (dietary intake) and from foods and supplements combined (total intake) and of dietary alpha-carotene and beta-carotene were associated with a lower risk of gastric cancer. The multivariate relative risks for the highest versus lowest quartiles of intake were 0.53 (95% CI: 0.32, 0.89; P for trend = 0.02) for total vitamin A, 0.56 (95% CI: 0.33, 0.95; P for trend = 0.05) for total retinol, 0.50 (95% CI: 0.30, 0.83; P for trend = 0.03) for alpha-carotene, and 0.55 (95% CI: 0.32, 0.94; P for trend = 0.07) for beta-carotene. No significant associations were found for beta-cryptoxanthin, lutein and zeaxanthin, or lycopene intake. CONCLUSION: High intakes of vitamin A, retinol, and provitamin A carotenoids may reduce the risk of gastric cancer.     

Dietary intakes and blood concentrations of antioxidant vitamins in German vegans

We report on an evaluation of intake and blood concentrations of antioxidant vitamins in a cross-sectional study of 104 German vegans, and examine the association between blood concentration of antioxidant vitamins and their intake as well as fruit and vegetable intake. Comparisons are made with dietary reference intakes and established threshold values (ETV) for blood concentrations. Mean intakes of vitamin C, E, and beta-carotene were higher than actual recommendations, but comparable to reported intakes in other vegan cohorts. Mean blood concentrations were 0.76 micromol/L for beta-carotene and 117 micromol/L for vitamin C, so that nearly all participants showed concentrations that were above the ETV for the prevention of chronic diseases. Although mean vitamin E intake was 24.8 mg/day, only 32% of female and 18% of male participants showed plasma concentrations above the ETV. However, the mean vitamin E/cholesterol ratio was high (5.97), indicating a good protection of low-density lipoprotein (LDL) against peroxidation. Of the reported antioxidant vitamins, only plasma vitamin C concentration was a good biomarker of fruit and vegetable intake. The high concentration of antioxidative compounds in plasma may be one of the reasons for the lower incidence of chronic diseases in people consuming a plant-only diet.     

Nutrient and food intake in relation to serum leptin concentration among young Japanese women

OBJECTIVE: Little is known about the relation of modifiable dietary factors to circulating leptin concentrations, particularly in young adults and non-Western populations. We examined cross-sectional associations between nutrient and food intake and serum leptin concentration in young Japanese women. METHODS: Subjects were 424 female Japanese dietetic students 18-22 y of age. Intake of macronutrients (protein, total fat; saturated, monounsaturated, and polyunsaturated fatty acids; and carbohydrate), dietary fiber, and 12 food groups was assessed with a validated, self-administered, comprehensive, diet history questionnaire. Fasting blood samples were collected, and serum leptin concentrations were measured by radioimmunoassay. RESULTS: For nutrients, only dietary fiber was a significant determinant of serum leptin concentration. Increasing dietary fiber intake was associated with lower serum leptin concentration independent of potential confounding factors, including body mass index (mean serum leptin concentrations in the lowest and highest quintiles of dietary fiber intake were 8.6 and 7.5 ng/mL, respectively; P for trend = 0.026). Vegetables and pulses were the only foods significantly associated with serum leptin concentration, with higher intakes independently associated with lower concentrations (mean serum leptin concentrations in the lowest and highest quintiles of intake were 8.1 and 7.0 ng/mL, P for trend = 0.007, for vegetables and 8.8 and 7.6 ng/mL, P for trend = 0.019, for pulses, respectively). CONCLUSION: Intake of dietary fiber, vegetables, and pulses showed an independent inverse association with serum leptin concentration in a group of young Japanese women.     

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.