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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    Repositioning of the global epicentre of non-optimal cholesterol
    Taddei, Cristina ; Zhou, Bin ; Bixby, Honor ; Carrillo-Larco, Rodrigo M. ; Danaei, Goodarz ; Jackson, Rod T. ; Farzadfar, Farshad ; Sophiea, Marisa K. ; Cesare, Mariachiara Di; Iurilli, Maria Laura Caminia ; Martinez, Andrea Rodriguez ; Asghari, Golaleh ; Dhana, Klodian ; Gulayin, Pablo ; Kakarmath, Sujay ; Santero, Marilina ; Voortman, Trudy ; Riley, Leanne M. ; Cowan, Melanie J. ; Savin, Stefan ; Bennett, James E. ; Stevens, Gretchen A. ; Paciorek, Christopher J. ; Aekplakorn, Wichai ; Cifkova, Renata ; Giampaoli, Simona ; Kengne, Andre Pascal ; Khang, Young Ho ; Kuulasmaa, Kari ; Laxmaiah, Avula ; Margozzini, Paula ; Mathur, Prashant ; Nordestgaard, Børge G. ; Zhao, Dong ; Aadahl, Mette ; Abarca-Gómez, Leandra ; Rahim, Hanan Abdul ; Abu-Rmeileh, Niveen M. ; Acosta-Cazares, Benjamin ; Adams, Robert J. ; Ferrieres, Jean ; Geleijnse, Johanna M. ; He, Yuna ; Jacobs, Jeremy M. ; Kromhout, Daan ; Ma, Guansheng ; Dam, Rob M. van; Wang, Qian ; Wang, Ya Xing ; Wang, Ying Wei - \ 2020
    Nature 582 (2020)7810. - ISSN 0028-0836 - p. 73 - 77.

    High blood cholesterol is typically considered a feature of wealthy western countries1,2. However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world3 and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health4,5. However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol—which is a marker of cardiovascular risk—changed from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million–4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.

    The association between dietary and skin advanced glycation end products: the Rotterdam Study
    Chen, Jinluan ; Waqas, Komal ; Tan, Robby Carlo ; Voortman, Trudy ; Ikram, M.A. ; Nijsten, Tamar E.C. ; De Groot, Lisette C.P.G.M. ; Uitterlinden, André G. ; Zillikens, M.C. - \ 2020
    American Journal of Clinical Nutrition 112 (2020)1. - ISSN 0002-9165 - p. 129 - 137.
    Advanced glycation end products (AGEs) accumulate in tissues with age and in conditions such as diabetes mellitus and chronic kidney disease (CKD), and they may be involved in age-related diseases. Skin AGEs measured as skin autofluorescence (SAF) are a noninvasive reflection of long-term AGE accumulation in tissues. Whether AGEs present in the diet (dAGEs) contribute to tissue AGEs is unclear.
    Our aim was to investigate the association between dietary and skin AGEs in the Rotterdam Study, a population-based cohort of mainly European ancestry.
    In 2515 participants, intake of 3 dAGEs [carboxymethyl-lysine (CML), N-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MGH1), and carboxyethyl-lysine (CEL)] was estimated using FFQs and the content of AGEs measured in commonly consumed foods. SAF was measured 5 y (median value) later using an AGE Reader. The association of dAGEs with SAF was analyzed in linear regression models and stratified for diabetes and chronic kidney disease (CKD, defined as estimated glomerular filtration rate ≤60 mL/min) status.
    Mean ± SD intake was 3.40 ±0.89 mg/d for CML, 28.98 ±7.87 mg/d for MGH1, and 3.11 ±0.89 mg/d for CEL. None of them was associated with SAF in the total study population. However, in stratified analyses, CML was positively associated with SAF after excluding both individuals with diabetes and individuals with CKD: 1 SD higher daily CML intake was associated with a 0.03 (95% CI: 0.009, 0.05) arbitrary units higher SAF. MGH1 and CEL intake were not significantly associated with SAF. Nevertheless, the associations were stronger when the time difference between dAGEs and SAF measurements was shorter.
    Higher dietary CML intake was associated with higher SAF only among participants with neither diabetes nor CKD, which may be explained by high AGE formation in diabetes and decreased excretion in CKD or by dietary modifications in these disease groups. The dAGE–SAF associations were also modified by the time difference between measurements. Our results suggest that dAGEs can influence tissue AGE accumulation and possibly thereby age-related diseases. This trial was registered at the Netherlands National Trial Register as NTR6831 ( and at the WHO International Clinical Trials Registry Platform as NTR6831 (
    A context analysis on how oral care is delivered in hospitalised patients: A mixed-methods study
    Noort, Harm H.J. van; Witteman, Ben J.M. ; Hertog-Voortman, Ria den; Everaars, Babette ; Vermeulen, Hester ; Huisman-de Waal, Getty - \ 2020
    Journal of Clinical Nursing 29 (2020)11-12. - ISSN 0962-1067 - p. 1991 - 2003.
    fundamental care - hospitalised patients - interviews - mixed methods - nondental care professional - nursing - oral care - oral health - oral health assessment tool - oral hygiene

    Aims and Objectives: To analyse oral care delivery in one hospital through exploring experiences from both nurses’ and patients’ perspectives and examining patients’ oral health. Background: Oral health problems are associated with undernutrition and other general health outcomes. Although oral care belongs to the essentials of nursing, it is often neglected. Improving oral health may require behaviour change of both nurses and patients. Defining tailored strategies need a clear view on the context. Design: A context analysis in one hospital using a convergent parallel mixed-methods design was reported following the EQUATOR guidelines using two checklists: COnsolidated criteria for REporting Qualitative research (qualitative research) and STROBE (observational research). Methods: Semi-structured interviews were conducted with 19 nurses and 11 patients. The topic list was based on the Integrated Change Model. Prospective oral examination was performed among 91 surgical patients using the Oral Health Assessment Tool (OHAT). Results: Nurses acknowledged that they did not prioritise oral care in daily practice. Furthermore, they lacked knowledge and skills to identify and provide care for oral problems. Nurses mentioned helpful resources to perform oral care, like standardised language and instruments. However, they had no access to or were unaware of them. Patients admitted that they did not prioritise oral care due to their sickness during hospitalisation, were unaware of the importance of oral care, but felt responsible for their oral care. The most prominent oral problems identified with the OHAT were unclean mouths (n = 75, 82%), unhealthy gum and tissues (n = 55, 60%) and dry mouth (n = 42, 46%). Conclusions: This context analysis identified inadequate oral care due to lack of positive attitude and knowledge in both nurses and patients, skills for nurses, and resources. Relevance to Clinical Practice: The behavioural factors indicate strategies for development of a multicomponent intervention to improve oral care in this hospital, nutritional status and general health outcomes.

    B-vitamins and body composition: integrating observational and experimental evidence from the B-PROOF study
    Oliai Araghi, Sadaf ; Braun, Kim V.E. ; Velde, Nathalie van der; Dijk, Suzanne C. van; Schoor, Natasja M. van; Zillikens, M.C. ; Groot, Lisette C.P.G.M. de; Uitterlinden, Andre G. ; Stricker, Bruno H. ; Voortman, Trudy ; Kiefte-de Jong, Jessica C. - \ 2020
    European Journal of Nutrition 59 (2020). - ISSN 1436-6207 - p. 1253 - 1262.
    BMI - Body composition - Effect of vitamin B12 and folic acid on obesity - Fat (Free) mass - Vitamin B12 and folic acid

    Purpose: Higher folate and vitamin-B12 have been linked to lower risk of overweight. However, whether this is a causal effect of these B-vitamins on obesity risk remains unclear and evidence in older individuals is scarce. This study aimed to assess the role of B-vitamin supplementation and levels on body composition in older individuals. Methods: A double-blind, randomized controlled trial in 2919 participants aged ≥ 65 years with elevated homocysteine levels. The intervention comprised a 2-year supplementation with a combination of folic acid (400 µg) and vitamin B12 (500 µg), or with placebo. Serum folate, vitamin-B12, active vitamin-B12 (HoloTC), methylmalonic acid (MMA), and anthropometrics were measured at baseline and after 2 years of follow-up. Dietary intake of folate and vitamin-B12 was measured at baseline in a subsample (n = 603) using a validated food-frequency questionnaire. Fat mass index (FMI) and fat-free mass index (FFMI) were assessed with Dual Energy X-ray absorptiometry (DXA). Results: Cross-sectional analyses showed that a 1 nmol/L higher serum folate was associated with a 0.021 kg/m 2 lower BMI (95% CI − 0.039; − 0.004). Higher HoloTC (per pmol/L log-transformed) was associated with a 0.955 kg/m 2 higher FMI (95% CI 0.262; 1.647), and higher MMA (per μgmol/L) was associated with a 1.108 kg/m 2 lower FMI (95% CI − 1.899; − 0.316). However, random allocation of B-vitamins did not have a significant effect on changes in BMI, FMI or FFMI during 2 years of intervention. Conclusions: Although observational data suggested that folate and vitamin B12 status are associated with body composition, random allocation of a supplement with both B-vitamins combined versus placebo did not confirm an effect on BMI or body composition.

    Diet quality in childhood : the Generation R Study
    Velde, Laura A. van der; Nguyen, Anh N. ; Schoufour, Josje D. ; Geelen, Anouk ; Jaddoe, Vincent W.V. ; Franco, Oscar H. ; Voortman, Trudy - \ 2019
    European Journal of Nutrition 58 (2019). - ISSN 1436-6207 - p. 1259 - 1269.
    Determinants - Diet quality - Dietary patterns - Epidemiology - Tracking - Validation
    Purpose: We aimed to evaluate diet quality of 8-year-old children in the Netherlands, to identify sociodemographic and lifestyle correlates of child diet quality, and to examine tracking of diet quality from early to mid-childhood. Methods: For 4733 children participating in a population-based cohort, we assessed dietary intake using a validated food-frequency questionnaire at a median age of 8.1 years (interquartile range 8.0–8.2) (2011–2014). Based on dietary guidelines, we developed and validated a food-based diet quality score for children consisting of ten components (score 0–10): sufficient intake of vegetables; fruit; whole grains; fish; legumes; nuts; dairy; oils and soft fats; and low intake of sugar-containing-beverages; and high-fat and processed meat. Results: We observed a mean (± SD) diet quality score of 4.5 (± 1.2) out of a maximum of 10. On average, intake of legumes, nuts, and oils or soft fats was below recommendations, whereas intake of sugar-containing beverages and high-fat or processed meat was higher than recommended. The main factors associated with higher diet quality were higher maternal educational level (β = 0.29, 95% CI 0.21, 0.37 versus low education), higher household income (β = 0.15, 95% CI 0.05, 0.25 versus low income), no maternal smoking (β = 0.13, 95% CI 0.02, 0.25 versus current smoking), and less screen time (β = 0.31, 95% CI 0.24, 0.38)—all independent of each other. For children with available dietary data at age 1 year (n = 2608), we observed only weak tracking of diet quality from early to mid-childhood (Pearson’s r = 0.19, k = 0.11 for extreme quartiles). Conclusion: Overall diet quality of 8-year-old children did not conform to dietary guidelines, especially for children having more screen time, children of lower educated or smoking mothers, or from lower-income households.
    Verdamping van droogteminnende duinvegetatie : Extended abstract
    Voortman, Bernard ; Bartholomeus, Ruud ; Zee, S.E.A.T.M. van der; Witte, J.P.M. - \ 2018
    Stromingen : vakblad voor hydrologen 32 (2018)2. - ISSN 1382-6069 - p. 7 - 12.
    Op 21 september 2018 was de openbare verdediging van het proefschrift "Evaporationfrom dry dune vegetation" door Bernard Voortman. Het proefschrift biedt kwantitatieve inzichten in het verdampingsgedrag van droogteminnende duinvegetaties in vroegesuccessiestadia (kaal zand, mos, gras en heide). We onderzochten onder andere de invloed van het dichtgroeien van natuurgebieden en van het veranderende klimaat op deverdamping. Deze inzichten komen ten goede aan betere grondwatermodellen, maarook aan de vergroting van de grondwateraanvulling via een gericht vegetatiebeheer.
    Aandacht nodig voor effect mossen op grondwaterbalans
    Voortman, B.R. ; Bartholomeus, Ruud ; Zee, S.E.A.T.M. van der; Witte, J.M. - \ 2018
    Land + Water (2018)11. - ISSN 0926-8456
    Evaporation from dry dune vegetation
    Voortman, Bernard Ruben - \ 2018
    VU University Amsterdam. Promotor(en): J.P.M. Witte; S.E.A.T.M. van der Zee, co-promotor(en): R.P. Bartholomeus. - Amsterdam : Vrije Universiteit - ISBN 9789463611299 - 136
    Evaporation from (Blue-)Green Roofs : Assessing the benefits of a storage and capillary irrigation system based on measurements and modeling
    Cirkel, Dirk Gijsbert ; Voortman, Bernard R. ; Veen, Thijs van; Bartholomeus, Ruud P. - \ 2018
    Water 10 (2018)9. - ISSN 2073-4441
    Blue-green roofs - Capillary irrigation - Latent heat flux - Lysimeter - Potential and actual evaporation - Sedums - Sensible heat flux - Urban areas - Water availability

    Worldwide cities are facing increasing temperatures due to climate change and increasing urban density. Green roofs are promoted as a climate adaptation measure to lower air temperatures and improve comfort in urban areas, especially during intensive dry and warm spells. However, there is much debate on the effectiveness of this measure, because of a lack of fundamental knowledge about evaporation from different green roof systems. In this study, we investigate the water and energy balance of different roof types on a rooftop in Amsterdam, the Netherlands. Based on lysimeter measurements and modeling, we compared the water and energy balance of a conventional green roof with blue-green roofs equipped with a novel storage and capillary irrigation system. The roofs were covered either with Sedum or by grasses and herbs. Our measurements and modeling showed that conventional green roof systems (i.e., a Sedum cover and a few centimeters of substrate) have a low evaporation rate and due to a rapid decline in available moisture, a minor cooling effect. Roofs equipped with a storage and capillary irrigation system showed a remarkably large evaporation rate for Sedum species behaving as C3 plants during hot, dry periods. Covered with grasses and herbs, the evaporation rate was even larger. Precipitation storage and capillary irrigation strongly reduced the number of days with dry-out events. Implementing these systems therefore could lead to better cooling efficiencies in cities.

    Multiple effects of cold exposure on livers of male mice
    Grefhorst, Aldo ; Beukel, Johanna C. van den; Dijk, Wieneke ; Steenbergen, Jacobie ; Voortman, Gardi J. ; Leeuwenburgh, Selmar ; Visser, Theo J. ; Kersten, Sander ; Friesema, Edith C.H. ; Themmen, Axel P.N. ; Visser, Jenny A. - \ 2018
    Journal of Endocrinology 238 (2018)2. - ISSN 0022-0795 - p. 91 - 106.
    Apolipoprotein - Cholesterol - Lipid - Liver

    Cold exposure of mice is a common method to stimulate brown adipose tissue (BAT) activity and induce browning of white adipose tissue (WAT) that has beneficial effects on whole-body lipid metabolism, including reduced plasma triglyceride (TG) concentrations. The liver is a key regulatory organ in lipid metabolism as it can take up as well as oxidize fatty acids. The liver can also synthesize, store and secrete TGs in VLDL particles. The effects of cold exposure on murine hepatic lipid metabolism have not been addressed. Here, we report the effects of 24-h exposure to 4°C on parameters of hepatic lipid metabolism of male C57BL/6J mice. Cold exposure increased hepatic TG concentrations by 2-fold (P < 0.05) but reduced hepatic lipogenic gene expression. Hepatic expression of genes encoding proteins involved in cholesterol synthesis and uptake such as the LDL receptor (LDLR) was significantly increased upon cold exposure. Hepatic expression of Cyp7a1 encoding the rate-limiting enzyme in the classical bile acid (BA) synthesis pathway was increased by 4.3-fold (P < 0.05). Hepatic BA concentrations and fecal BA excretion were increased by 2.8- and 1.3-fold, respectively (P < 0.05 for both). VLDL-TG secretion was reduced by approximately 50% after 24 h of cold exposure (P < 0.05). In conclusion, cold exposure has various, likely intertwined effects on the liver that should be taken into account when studying the effects of cold exposure on wholebody metabolism.

    Risk thresholds for alcohol consumption: combined analysis of individual-participant data for 599 912 current drinkers in 83 prospective studies
    Wood, Angela M. ; Kaptoge, Stephen ; Schoufour, Josje ; Kromhout, D. ; Voortman, Trudy ; Sweeting, Michael ; Verschuren, W.M.M. ; Salomaa, Veikko ; Danesh, John - \ 2018
    The Lancet 391 (2018)10129. - ISSN 0140-6736 - p. 1513 - 1523.
    Background Low-risk limits recommended for alcohol consumption vary substantially across different national guidelines. To define thresholds associated with lowest risk for all-cause mortality and cardiovascular disease, we studied individual-participant data from 599 912 current drinkers without previous cardiovascular disease. Methods We did a combined analysis of individual-participant data from three large-scale data sources in 19 high-income countries (the Emerging Risk Factors Collaboration, EPIC-CVD, and the UK Biobank). We characterised dose–response associations and calculated hazard ratios (HRs) per 100 g per week of alcohol (12·5 units per week) across 83 prospective studies, adjusting at least for study or centre, age, sex, smoking, and diabetes. To be eligible for the analysis, participants had to have information recorded about their alcohol consumption amount and status (ie, non-drinker vs current drinker), plus age, sex, history of diabetes and smoking status, at least 1 year of follow-up after baseline, and no baseline history of cardiovascular disease. The main analyses focused on current drinkers, whose baseline alcohol consumption was categorised into eight predefined groups according to the amount in grams consumed per week. We assessed alcohol consumption in relation to all-cause mortality, total cardiovascular disease, and several cardiovascular disease subtypes. We corrected HRs for estimated long-term variability in alcohol consumption using 152 640 serial alcohol assessments obtained some years apart (median interval 5·6 years [5th–95th percentile 1·04–13·5]) from 71 011 participants from 37 studies. Findings In the 599 912 current drinkers included in the analysis, we recorded 40 310 deaths and 39 018 incident cardiovascular disease events during 5·4 million person-years of follow-up. For all-cause mortality, we recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100 g per week. Alcohol consumption was roughly linearly associated with a higher risk of stroke (HR per 100 g per week higher consumption 1·14, 95% CI, 1·10–1·17), coronary disease excluding myocardial infarction (1·06, 1·00–1·11), heart failure (1·09, 1·03–1·15), fatal hypertensive disease (1·24, 1·15–1·33); and fatal aortic aneurysm (1·15, 1·03–1·28). By contrast, increased alcohol consumption was log-linearly associated with a lower risk of myocardial infarction (HR 0·94, 0·91–0·97). In comparison to those who reported drinking >0–≤100 g per week, those who reported drinking >100–≤200 g per week, >200–≤350 g per week, or >350 g per week had lower life expectancy at age 40 years of approximately 6 months, 1–2 years, or 4–5 years, respectively. Interpretation In current drinkers of alcohol in high-income countries, the threshold for lowest risk of all-cause mortality was about 100 g/week. For cardiovascular disease subtypes other than myocardial infarction, there were no clear risk thresholds below which lower alcohol consumption stopped being associated with lower disease risk. These data support limits for alcohol consumption that are lower than those recommended in most current guidelines.
    Serum folate and vitamin B12 are associated with body composition in elderly: The B-PROOF study
    Oliai Araghi, S. ; Braun, K.V.E. ; Velde, Nathalie van der; Dijk, S. van; Schoor, Natasja M. van; Zillikens, M.C. ; Groot, C.P.G.M. de; Uitterlinden, André G. ; Stricker, B.H. ; Voortman, Trudy ; Kiefte-de Jong, J.C. - \ 2018
    Low-Frequency Synonymous Coding Variation in CYP2R1 Has Large Effects on Vitamin D Levels and Risk of Multiple Sclerosis
    Manousaki, Despoina ; Dudding, Tom ; Haworth, Simon ; Hsu, Yi Hsiang ; Liu, Ching Ti ; Medina-Gómez, Carolina ; Voortman, Trudy ; Velde, Nathalie Van Der; Melhus, Håkan ; Vandenput, Liesbeth ; Noordam, Raymond ; Forgetta, Vincenzo ; Greenwood, Celia M.T. ; Biggs, Mary L. ; Psaty, Bruce M. ; Rotter, Jerome I. ; Zemel, Babette S. ; Mitchell, Jonathan A. ; Taylor, Bruce ; Lorentzon, Mattias ; Karlsson, Magnus ; Jaddoe, Vincent W.V. ; Tiemeier, Henning ; Campos-Obando, Natalia ; Franco, Oscar H. ; Utterlinden, Andre G. ; Broer, Linda ; Schoor, Natasja M. van; Ham, Annelies C. ; Ikram, Arfan M.A. ; Karasik, David ; Mutsert, Renée De; Rosendaal, Frits R. ; Heijer, Martin den; Wang, Thomas J. ; Lind, Lars ; Orwoll, Eric S. ; Mook-Kanamori, Dennis O. ; Michaëlsson, Karl ; Kestenbaum, Bryan ; Ohlsson, Claes ; Mellström, Dan ; Groot, Lisette C.P.G.M. de; Grant, Struan F.A. ; Kiel, Douglas P. ; Zillikens, M.C. ; Rivadeneira, Fernando ; Sawcer, Stephen ; Timpson, Nicholas J. ; Richards, J.B. - \ 2017
    American Journal of Human Genetics 101 (2017)2. - ISSN 0002-9297 - p. 227 - 238.
    GWAS - Low-frequency genetic variants - Multiple sclerosis - Vitamin D
    Vitamin D insufficiency is common, correctable, and influenced by genetic factors, and it has been associated with risk of several diseases. We sought to identify low-frequency genetic variants that strongly increase the risk of vitamin D insufficiency and tested their effect on risk of multiple sclerosis, a disease influenced by low vitamin D concentrations. We used whole-genome sequencing data from 2,619 individuals through the UK10K program and deep-imputation data from 39,655 individuals genotyped genome-wide. Meta-analysis of the summary statistics from 19 cohorts identified in CYP2R1 the low-frequency (minor allele frequency = 2.5%) synonymous coding variant g.14900931G>A (p.Asp120Asp) (rs117913124[A]), which conferred a large effect on 25-hydroxyvitamin D (25OHD) levels (-0.43 SD of standardized natural log-transformed 25OHD per A allele; p value = 1.5 × 10-88). The effect on 25OHD was four times larger and independent of the effect of a previously described common variant near CYP2R1. By analyzing 8,711 individuals, we showed that heterozygote carriers of this low-frequency variant have an increased risk of vitamin D insufficiency (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.78-2.78, p = 1.26 × 10-12). Individuals carrying one copy of this variant also had increased odds of multiple sclerosis (OR = 1.4, 95% CI = 1.19-1.64, p = 2.63 × 10-5) in a sample of 5,927 case and 5,599 control subjects. In conclusion, we describe a low-frequency CYP2R1 coding variant that exerts the largest effect upon 25OHD levels identified to date in the general European population and implicates vitamin D in the etiology of multiple sclerosis.
    Een nieuwe en handzame lysimeter: eerste stap naar een nationaal netwerk voor de werkelijke verdamping?
    Voortman, Bernard ; Witte, J.P. ; Rheenen, Hans van; Bosveld, F. ; Elbers, J.A. ; Bolt, F.J.E. van der; Heijkers, J. ; Hoogendoorn, Jan ; Bolman, A. ; Spek, T. ; Voogt, M. - \ 2016
    Stromingen : vakblad voor hydrologen 22 (2016)2. - ISSN 1382-6069 - p. 49 - 63.
    hydrologie - neerslag - waterbalans - grondwater - lysimeters - evaporatie - hydrology - precipitation - water balance - groundwater - lysimeters - evaporation
    Vrijwel overal op aarde verdampt meer dan de helft van het neerslagwater, ook in Nederland. Toch wordt deze grote verliespost in ons land slechts sporadisch gemeten. Door inspanningen van kennisinstituten, bedrijven en overheid is daarom een lysimeter ontwikkeld. Metingen in 2014 en 2015 op twee locaties vertonen opvallende verschillen, maar ook grote overeenkomsten, met eddy-correlatiemetingen. Schattingen van de verdamping via satellietdata zijn hoger dan de metingen. Tijd daarom, om metingen in het veld te combineren met modellen en waarnemingen vanuit de ruimte
    Macronutrient intakes in infancy are associated with sleep duration in toddlerhood
    Kocevska, Desana ; Voortman, T. ; Dashti, Hassan ; Feskens, E.J.M. - \ 2016
    The Journal of Nutrition 146 (2016)6. - ISSN 0022-3166 - p. 1250 - 1256.
    Background: Dietary composition has been associated with sleep indexes. However, most of the evidence is based on cross-sectional data, and studies in young children are lacking.

    Objective: The aim of this study was to explore the longitudinal associations of macronutrient composition of the diet with sleep duration and consolidation (number of awakenings) in infancy and early childhood.

    Methods: The study was performed in 3465 children from the Generation R Study, a population-based cohort study in the Netherlands. Mothers reported their child’s food intake at 13 mo of age by using a validated food-frequency questionnaire and their child’s sleep patterns at 2 and 3 y of age. We used nutrient substitution models to assess the associations of relative macronutrient intakes with sleep indexes and adjusted the models for sociodemographic and lifestyle factors.

    Results: Isocaloric substitution of fat intake by protein or carbohydrate in infancy was associated with longer total sleep duration at 2 but not 3 y of age. For each 5% increase in energy intake of either protein or carbohydrate at the expense of fat, sleep duration at 2 y of age was longer by 6 min (95% CI: 0.4, 12 min) and 4 min (95% CI: 2, 6 min), respectively. Further exploration of macronutrient subtypes indicated no consistent differences between saturated or unsaturated fat and that intake of plant compared with animal protein or Trp did not explain the association of higher total protein intake with longer sleep duration at 2 y of age. Replacing unsaturated with saturated fat was associated with 7 min (95% CI: −13, −1 min) shorter total sleep duration at 3 y of age. Macronutrient intakes were not associated with sleep consolidation.

    Conclusions: Our results suggest that the macronutrient composition of the diet is associated with sleep duration in young children. Future research should further study the causality of this association and explore the underlying mechanisms.
    Development of a food group-based diet score and its association with bone mineral density in the elderly: the Rotterdam Study
    Jonge, E.A.L. de; Kiefte-de Jong, J.C. ; Groot, C.P.G.M. de; Voortman, T. ; Schoufour, J.D. ; Zillikens, M.C. ; Hofman, A. ; Uitterlinden, A.G. ; Franco, O.H. ; Rivadeneira, F. - \ 2015
    Nutrients 7 (2015)8. - ISSN 2072-6643 - p. 6974 - 6990.
    No diet score exists that summarizes the features of a diet that is optimal for bone mineral density (BMD) in the elderly. Our aims were (a) to develop a BMD-Diet Score reflecting a diet that may be beneficial for BMD based on the existing literature, and (b) to examine the association of the BMD-Diet Score and the Healthy Diet Indicator, a score based on guidelines of the World Health Organization, with BMD in Dutch elderly participating in a prospective cohort study, the Rotterdam Study (n = 5144). Baseline dietary intake, assessed using a food frequency questionnaire, was categorized into food groups. Food groups that were consistently associated with BMD in the literature were included in the BMD-Diet Score. BMD was measured repeatedly and was assessed using dual energy X-ray absorptiometry. The BMD-Diet Score considered intake of vegetables, fruits, fish, whole grains, legumes/beans and dairy products as “high-BMD” components and meat and confectionary as “low-BMD” components. After adjustment, the BMD-Diet Score was positively associated with BMD (ß (95% confidence interval) = 0.009 (0.005, 0.012) g/cm2 per standard deviation). This effect size was approximately three times as large as has been observed for the Healthy Diet Indicator. The food groups included in our BMD-Diet Score could be considered in the development of future dietary guidelines for healthy ageing.
    Quantifying energy and water fluxes in dry dune ecosystems of the Netherlands
    Voortman, B.R. ; Bartholomeus, R.P. ; Zee, S.E.A.T.M. van der; Bierkens, M.F.P. ; Witte, J.M.P. - \ 2015
    Hydrology and Earth System Sciences 19 (2015). - ISSN 1027-5606 - p. 3787 - 3805.
    Coastal and inland dunes provide various ecosystem services that are related to groundwater, such as drinking water production and biodiversity. To manage groundwater in a sustainable manner, knowledge of actual evapotranspiration (ETa) for the various land covers in dunes is essential. Aiming at improving the parameterization of dune vegetation in hydrometeorological models, this study explores the magnitude of energy and water fluxes in an inland dune ecosystem in the Netherlands. Hydrometeorological measurements were used to parameterize the Penman–Monteith evapotranspiration model for four different surfaces: bare sand, moss, grass and heather. We found that the net longwave radiation (Rnl) was the largest energy flux for most surfaces during daytime. However, modeling this flux by a calibrated FAO-56 Rnl model for each surface and for hourly time steps was unsuccessful. Our Rnl model, with a novel submodel using solar elevation angle and air temperature to describe the diurnal pattern in radiative surface temperature, improved Rnl simulations considerably. Model simulations of evaporation from moss surfaces showed that the modulating effect of mosses on the water balance is species-dependent. We demonstrate that dense moss carpets (Campylopus introflexus) evaporate more (5 %, +14 mm) than bare sand (total of 258 mm in 2013), while more open-structured mosses (Hypnum cupressiforme) evaporate less (-30 %, -76 mm) than bare sand. Additionally, we found that a drought event in the summer of 2013 showed a pronounced delayed signal on lysimeter measurements of ETa for the grass and heather surfaces, respectively. Due to the desiccation of leaves after the drought event, and their feedback on the surface resistance, the potential evapotranspiration in the year 2013 dropped by 9 % (-37 mm) and 10 % (-61 mm) for the grass and heather surfaces, respectively, which subsequently led to lowered ETa of 8 % (-29 mm) and 7 % (-29 mm). These feedbacks are of importance for water resources, especially during a changing climate with an increasing number of drought days. Therefore, such feedbacks need to be integrated into a coupled plant physiological and hydrometeorological model to accurately simulate ETa. In addition, our study showed that groundwater recharge in dunes can be increased considerably by promoting moss vegetation, especially of open-structured moss species.
    The Development of a Diet Quality Score for Preschool Children and Its Validation and Determinants in the Generation R Study
    Voortman, T. ; Kiefte-de Jong, J.C. ; Geelen, A. ; Villamor, G.B. ; Moll, H.A. ; Jongste, J.C. de; Raat, H. ; Hofman, A. ; Jaddoe, V.W.V. ; Franco, O.H. ; Hooven, E.H. van den - \ 2015
    The Journal of Nutrition 145 (2015)2. - ISSN 0022-3166 - p. 306 - 314.
    healthy eating index - multiple imputation - measurement error - pattern-analysis - food - adolescents - associations - childhood - nutrition - validity
    Background: Although many studies have examined health effects of infant feeding, studies on diet quality shortly after the weaning and lactation period are scarce. Objectives: Our aims were to develop and evaluate a diet score that measures overall diet quality in preschool children and to examine the sociodemographic and lifestyle determinants of this score. Methods: On the basis of national and international dietary guidelines for young children, we developed a diet score containing 10 components: intake of vegetables; fruit; bread and cereals; rice, pasta, potatoes, and legumes; dairy; meat and eggs; fish; oils and fats; candy and snacks; and sugar-sweetened beverages. The total score ranged from 0 to 10 on a continuous scale and was standardized to an energy intake of 1200 kcal/d with the residual method. The score was evaluated in 3629 children participating in the Generation R Study, a population-based prospective cohort study. Food consumption was assessed with a food-frequency questionnaire (FFQ) at a median age of 13 mo. Results: The mean +/- SD diet score was 4.1 +/- 1.3. The food-based diet score was positively associated with intakes of many nutrients, including n-3 (omega-3)-31 fatty acids [FAs; 0.25 SD increase 195% CI: 0.22, 0.27) per 1 point increase in the diet score], dietary fiber [0.32 (95% CI: 0.30, 0.34)], and calcium [0.13 (95% CI: 0.11, 0.16)], and was inversely associated with intakes of sugars [-0.28(95% CI: -0.31, -0.26)] and saturated fat [-0.03 (95% CI: -0.05, -0.01)]. A higher diet score was associated with several health-conscious behaviors, such as maternal folic acid supplement use during pregnancy, no smoking during pregnancy, and children watching less television. Conclusion: We developed a novel food-based diet score for preschool children that could be applied in future studies to compare diet quality in early childhood and to investigate associations between diet in early childhood and growth, health, and development.
    Expertdialoog de Veluwe. Begrijpen we het watersysteem?
    Verhagen, F. ; Spek, T. ; Witte, F. ; Voortman, B. ; Moors, E.J. ; Querner, E.P. ; Eertwegh, G.A.P.H. van den - \ 2014
    Stromingen : vakblad voor hydrologen 20 (2014)3. - ISSN 1382-6069 - p. 5 - 19.
    geohydrologie - watersystemen - grondwaterstand - waterlopen - inventarisaties - veluwe - geohydrology - water systems - groundwater level - streams - inventories - veluwe
    De waterbel van De Veluwe staat volop in de belangstelling. Deze waterbel zorgt voor een continue stroom naar de beken en sprengen. Maar snappen we wel voldoende hoe het watersysteem werkt? Op basis van twee werksessies is beschikbare kennis op een rij gezet en zijn kennisleemtes gesignaleerd. Conclusie is dat we nog lang niet alles weten over de verdamping en het transport van water in de onverzadigde zone, twee processen die van grote invloed zijn op de beekafvoer.
    Unsaturated hydraulic properties of xerophilous mosses: towards implementation of moss covered soils in hydrological models
    Voortman, B.R. ; Bartholomeus, R.P. ; Bodegom, P.M. van; Gooren, H.P.A. ; Zee, S.E.A.T.M. van der; Witte, J.P.M. - \ 2014
    Hydrological Processes 28 (2014)26. - ISSN 0885-6087 - p. 6251 - 6264.
    evaporatie - bryophyta - hydraulisch geleidingsvermogen - korstmossen - mossen - hydrologie - waterbalans - bodemwaterretentie - modelleren - evaporation - bryophyta - hydraulic conductivity - lichens - mosses - hydrology - water balance - soil water retention - modeling - sphagnum moss - water - conductivity - bryophytes - desiccation - ecosystems - tolerance
    Evaporation from mosses and lichens can form a major component of the water balance, especially in ecosystems where mosses and lichens often grow abundantly, such as tundra, deserts and bogs. To facilitate moss representation in hydrological models, we parameterized the unsaturated hydraulic properties of mosses and lichens such that the capillary water flow through moss and lichen material during evaporation could be assessed. We derived the Mualem-van Genuchten parameters of the drying retention and the hydraulic conductivity functions of four xerophilous moss species and one lichen species. The shape parameters of the retention functions (2.17¿
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