Validation of a food frequency questionnaire to assess folate intake of Dutch elderly people

Folate is required for 1-carbon metabolism and deficiency in folate leads to megaloblastic anemia. Low levels of folate have been associated with increased risk of vascular disease. To investigate whether RDA of folate are met, habitual folate intake needs to be assessed reliably. We developed a FFQ to specifically measure folate intake over the previous 3 months in elderly people in the Netherlands. Major sources of folate intake, i.e. foods contributing to at least 80 % of the average folate intake, were identified through an analysis of the second Dutch Food Consumption Survey for the sub-population of men and women aged 50¿70. In 2000 and 2001, folate intake was estimated with this questionnaire in 1286 individuals aged 50-75 years. Concentrations of serum and erythrocyte folate served as biomarkers with which relative validity of the questionnaire was assessed. The same FFQ was repeated after 3 years in 803 subjects in order to assess long-term reproducibility. Mean folate intake was estimated to be 196 (sd 69) ¿g/d. Spearman correlation coefficients between folate intake and serum and erythrocyte concentrations were 0·14 (P <0·01) and 0·05 (P = 0·06) respectively. Spearman correlations between folate intakes measured at baseline and after 3 years were 0·58 (P <0·01). 47 % of the participants were classified in the same quartiles on the two occasions. Our FFQ showed a weak correlation between folate intake and blood folate concentrations and reproducibility was acceptable. This FFQ is able to rank subjects according to their folate intake

Intake of dietary folate vitamers and risk of colorectal carcinoma: results from The Netherlands Cohort Study

BACKGROUND. Several studies have reported inverse associations between folate intake and colorectal carcinoma risk. Few were prospective studies and none evaluated the association between the intake of individual folate vitamers and colorectal carcinoma risk. METHODS. The aim of the current study was to investigate the relationship between dietary folate intake and the risk of colorectal carcinoma in a large prospective cohort study in The Netherlands comprising 120,852 men and women aged 55-69 years. After 7.3 years of follow-up, 760 colon and 411 rectal carcinoma cases were available for analysis. Data processing and analysis used the case-cohort approach. A new Dutch database was used to estimate intakes of total and individual folate vitamers. RESULTS. Analyses adjusted for age, energy intake, family history of colorectal carcinoma, alcohol, vitamin C, iron, and dietary fiber intake yielded an inverse association between colon carcinoma risk and total dietary folate intake (rate ratio [RR]highest vs. lowest quintile, men: 0.73; 95% confidence interval [CI], 0.46-1.17, P trend = 0.03; women: 0.68; 95% CI, 0.39-1.20, P trend = 0.18). An inverse association between rectal carcinoma and total dietary folate intake was found only among men (RR highest vs. lowest quintile, men: 0.66; 95% CI, 0.35-1.21, P trend = 0.03). Analyses showed no clear difference in colorectal carcinoma risk associated with intake of different folate vitamers. CONCLUSIONS. Dietary folate intake was related inversely to colon and male rectal carcinoma risk. © 2002 American Cancer Society. Chemicals/CAS: Folic Acid, 59-30-3; Hematinic

A prospective cohort study on intake of retinol, vitamins C and E and carotenoids and prostate cancer risk (Netherlands)

Objectives: The roles of retinol, vitamins C and E, and carotenoids as risk factors for prostate carcinoma are still questionable. We evaluated these in the Netherlands Cohort Study. Methods: The cohort study consisted of 58,279 men ages 55-69 years at baseline in 1986. After 6.3 years of follow-up, 642 incident prostate carcinoma cases were available for analysis. Intakes of retinol, vitamins C and E, and several carotenoids were measured by means of a 150-item semi-quantitative food-frequency questionnaire. Results: In multivariate analyses a positive association with prostate cancer risk was observed for intake of β-cryptoxanthin. Rate ratios (RRs) in increasing quintiles were 1.00 (ref), 0.94, 1.01, 1.16, 1.41; p-trend <0.01. For intake of retinol, vitamins C and E and other carotenoids (α-carotene, β-carotene, lycopene, and lutein/zeaxanthin) no effect on overall prostate cancer risk was found. RRs for vitamin supplement use were decreased, but not significantly. Among nondrinkers, nonsignificant inverse associations were observed for intake of retinol, α-carotene, and β-carotene (RRs, highest vs lowest quintile, were 0.23, 0.60, and 0.76, respectively). Among drinkers, β-cryptoxanthin was positively associated (RR highest vs lowest quintile = 1.40). Conclusions: These data show a positive association between β-cryptoxanthin and prostate cancer risk. Our study also shows inverse associations for retinol, α-carotene, and β-carotene among nondrinkers; this suggests an interaction between vitamins and alcohol consumption, which needs confirmation. Lycopene was not associated with prostate cancer. Chemicals/CAS: Antioxidants; Ascorbic Acid, 50-81-7; beta Carotene, 7235-40-7; Carotenoids, 36-88-4; cryptoxanthin, 472-70-8; Vitamin A, 11103-57-4; Vitamin E, 1406-18-4; Xanthophyll

The contribution of various foods to intake of vitamin A and carotenoids in the Netherlands

This study presents data on dietary intake of specific carotenoids in the Netherlands, based on a recently developed food composition database for carotenoids. Regularly eaten vegetables, the main dietary source of carotenoids, were sampled comprehensively and analysed with modern analytic methods. The database was complemented with data from recent literature and information from food manufacturers. In addition, data on intake of vitamin A are presented, which are based on the most recent update of the Dutch Food Composition Table. Intake of vitamin A was calculated for adult participants of the second Dutch National Food Consumption Survey in 1992, whereas intake of carotenoids was calculated for participants of the Dutch Cohort Study on diet and cancer, aged 55 to 69 in 1986. Mean intake of vitamin A amounted to 1.1 and 0.9 mg RE/day for men and women, respectively; the contributions of meat, fats and oils, vegetables and dairy products to total intake were 35%, 24%, 16%, and 16%, respectively. Mean intake of α-carotene, β-carotene and lutein plus zeaxanthin was 0.7, 3.0, and 2.5 mg/day respectively for both men and women, while mean intake of lycopene was 1.0 mg/day for men and 1.3 mg/day for women. The most important foods contributing to intake of β-carotene and lutein plus zeaxanthin were carrots β-carotene only), spinach, endive and kale