Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    We will mail you new results for this query: keywords==homocysteine concentrations
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Prediction of fruit and vegatable intake from biomarkers using individual participant data of diet-controntrolled intervantion studies
Souverein, O.W. ; Vries, J.H.M. de; Freese, R. ; Waltz, B. ; Bub, A. ; Winkels, R.M. ; Voet, H. van der; Boshuizen, H.C. - \ 2015
The British journal of nutrition 113 (2015)9. - ISSN 0007-1145 - p. 1396 - 1409.
food-frequency questionnaire - beta-carotene - plasma carotenoids - homocysteine concentrations - fractional polynomials - lipid-peroxidation - healthy nonsmokers - serum carotenoids - oxidative stress - controlled-trial
Fruit and vegetable consumption produces changes in several biomarkers in blood. The present study aimed to examine the dose–response curve between fruit and vegetable consumption and carotenoid (a-carotene, ß-carotene, ß-cryptoxanthin, lycopene, lutein and zeaxanthin), folate and vitamin C concentrations. Furthermore, a prediction model of fruit and vegetable intake based on these biomarkers and subject characteristics (i.e. age, sex, BMI and smoking status) was established. Data from twelve diet-controlled intervention studies were obtained to develop a prediction model for fruit and vegetable intake (including and excluding fruit and vegetable juices). The study population in the present individual participant data meta-analysis consisted of 526 men and women. Carotenoid, folate and vitamin C concentrations showed a positive relationship with fruit and vegetable intake. Measures of performance for the prediction model were calculated using cross-validation. For the prediction model of fruit, vegetable and juice intake, the root mean squared error (RMSE) was 258·0 g, the correlation between observed and predicted intake was 0·78 and the mean difference between observed and predicted intake was - 1·7 g (limits of agreement: - 466·3, 462·8 g). For the prediction of fruit and vegetable intake (excluding juices), the RMSE was 201·1 g, the correlation was 0·65 and the mean bias was 2·4 g (limits of agreement: - 368·2, 373·0 g). The prediction models which include the biomarkers and subject characteristics may be used to estimate average intake at the group level and to investigate the ranking of individuals with regard to their intake of fruit and vegetables when validating questionnaires that measure intake.
Gender and body size affect the response of erythrocyte folate to folic acid treatment
Winkels, R.M. ; Brouwer, I.A. ; Verhoef, P. ; Oort, F.V.A. van; Durga, J. ; Katan, M.B. - \ 2008
The Journal of Nutrition 138 (2008)8. - ISSN 0022-3166 - p. 1456 - 1461.
dietary intakes rdi - controlled-trial - united-states - older-adults - homocysteine concentrations - nonpregnant women - blood folate - vitamin-c - supplementation - humans
The recommended dietary allowance (RDA) differs between men and women for some vitamins, but not for folate. The RDA for folate is derived mainly from metabolic studies in women. We assessed if men differ from women in their response of erythrocyte folate to folic acid supplementation. We used data from 2 randomized placebo-controlled trials with folic acid: a 3-y trial in which subjects ingested 800 mu g/d of folic acid (294 men and 112 women) and a 12-wk trial in which 187 men and 129 women ingested 0, 50, 100, 200, 400, 600, or 800 mu g/d of folic acid in a parallel design (n = 38-42 per treatment group). In the 3-y trial, the erythrocyte folate concentration increased 10% (143 nmol/L, [95%Cl 46, 241]) less in men than in women. In the 12-wk trial, regression analysis showed that the response of erythrocyte folate upon folic acid intake for men was 47 nmol/L lower than for women (P for beta(gender) = 0.022); for an intake of 800 mu g/d folic acid, this resulted in a 5% lower response in men than in women. Differences in lean body size explained 56% of the difference in response of erythrocyte folate between men and women in the 3-y trial and 70% in the 12-wk trial. Men need more folic acid than women to achieve the same erythrocyte folate concentration, mainly because men have a larger lean body mass. This could be an indication that the RDA for folate should be higher for men than for women, or that the RDA should be expressed per kilogram of lean body mass.
Bread cofortified with folic acid and vitamin B-12 improves the folate and vitamin B-12 status of healthy older people: a randomized controlled trial
Winkels, R.M. ; Brouwer, I.A. ; Clarke, R. ; Katan, M.B. ; Verhoef, P. - \ 2008
American Journal of Clinical Nutrition 88 (2008)2. - ISSN 0002-9165 - p. 348 - 355.
neural-tube defects - double-blind - homocysteine concentrations - food fortification - serum vitamin-b-12 - cognitive function - oral vitamin-b-12 - united-states - deficiency - supplementation
Background: Mandatory fortification of flour with folic acid has reduced the number of neural tube defects in North America. Concerns that high intakes of folic acid might mask vitamin B-12 deficiency in older persons have delayed the introduction of fortification in many European countries. Cofortification of flour with folic acid and vitamin B-12 could simultaneously improve folate and vitamin B-12 status. Objective: The objective was to estimate the effect of the consumption of bread fortified with modest amounts of folic acid and vitamin B-12 on folate and vitamin B-12 status in healthy older persons living in the Netherlands, where folic acid fortification is not taking place. Design: Men and women aged 50-75 y were randomly assigned in this 12-wk double-blind, placebo-controlled trial to consume bread fortified with 138 mu g folic acid and 9.6 mu g vitamin B-12 daily (n = 72) or unfortified bread (n = 70). Results: The consumption of fortified bread increased serum folate concentrations by 45% (mean: 6.3 nmol/L; 95% CI: 4.5, 8.1 nmol/L) and serum vitamin B-12 concentrations by 49% (mean: 102 pmol/L; 95% CI: 82, 122 pmol/L) relative to the placebo group. Fortified bread increased erythrocyte folate concentrations by 22% and holo-transcobalamin concentrations by 35%; it decreased homocysteine concentrations by 13% and methylmalonic acid concentrations by 10%. Consumption of fortified bread decreased the proportion of individuals with marginal serum vitamin B-12 concentrations (
Validation of a food frequency questionnaire to assess folate intake of Dutch elderly people
Rest, O. van de; Durga, J. ; Verhoef, P. ; Boonstra, A. ; Brants, H.A.M. - \ 2007
The British journal of nutrition 98 (2007)5. - ISSN 0007-1145 - p. 1014 - 1020.
folic-acid - homocysteine concentrations - dietary assessment - heart-disease - plasma folate - biomarker - fruit - risk - vitamin-b-12 - population
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.
Association of folate with hearing is dependent on the 5, 10-methylenetetrahydrofolate reductase 677C-->T mutation
Durga, J. ; Anteunis, L.J.C. ; Schouten, E.G. ; Bots, M.L. ; Kok, F.J. ; Verhoef, P. - \ 2006
Neurobiology of aging 27 (2006)3. - ISSN 0197-4580 - p. 482 - 489.
cardiovascular risk-factors - methylenetetrahydrofolate reductase - homocysteine concentrations - common mutation - disease - plasma - epidemiology - atherosclerosis - vitamin-b-12 - impairment
Vascular disease and its risk factors have been associated with the age-related hearing loss. We examined the association of elevated plasma homocysteine and its determinants with hearing levels. Pure-tone air conduction thresholds in 728 individuals with sensorineural hearing loss were not associated with homocysteine, erythrocyte folate and Vitamin B6. Low concentrations of serum folate and Vitamin B12 were associated with better hearing. When folate status was below the median, 5,10-methylenetetrahydrofolate reductase (MTHFR) 677TT homozygotes had similar hearing levels to subjects with a C allele. However, when folate status was above the median, MTHFR 677TT homozygotes had on an average 5 dB (p = 0.037) and 2.6 dB (p = 0.021) lower PTA-high and PTA-low hearing thresholds, respectively, than the subjects with a 677C allele. The relationship between serum folate and hearing thresholds appeared to be dependent on MTHFR 677 genotype (CC, r = 0.13, p = 0.034; TT, r = -0.10, p = 0.291). This supports the hypothesis that a greater one-carbon moiety commitment to de novo synthesis of nucleotides and an increase in formyl-folate derivatives relative to methyl-folate derivatives is protective for hearing.
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