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.

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Protein Oxidation in Plant Protein-Based Fibrous Products : Effects of Encapsulated Iron and Process Conditions
Estrada, Patrícia Duque ; Berton-Carabin, Claire C. ; Schlangen, Miek ; Haagsma, Anniek ; Pierucci, Anna Paola T.R. ; Goot, Atze Jan van der - \ 2018
Journal of Agricultural and Food Chemistry 66 (2018)42. - ISSN 0021-8561 - p. 11105 - 11112.
encapsulation - fibrous structures - iron - plant protein - protein oxidation

Plant protein-based fibrous structures have recently attracted attention because of their potential as meat replacer formulations. It is, however, unclear how the process conditions and fortification with micronutrients may affect the chemical stability of such products. Therefore, we aimed to investigate the effects of process conditions and the incorporation of iron (free and encapsulated) on protein oxidation in a soy protein-based fibrous product. First, the physicochemical stability of iron-loaded pea protein particles, used as encapsulation systems, was investigated when exposed to 100 or 140 °C. Second, protein oxidation was measured in the iron-fortified soy protein-based fibrous structures made at 100 or 140 °C. Exposure to high temperatures increased the carbonyl content in pea protein particles. The incorporation of iron (free or encapsulated) did not affect carbonyl content in the fibrous product, but the process conditions for making such products induced the formation of carbonyls to a fairly high extent.

Data from: X-Ray Diffraction of Iron Containing Samples: the Importance of a Suitable Configuration
Mos, Y.M. ; Vermeulen, Arnold C. ; Buisman, C.J.N. ; Weijma, J. - \ 2018
fluorescence - iron - radiation type - X-ray diffraction
RD results belonging to paper ‘X-Ray Diffraction of Iron Containing Samples: the Importance of a Suitable Configuration’
X-Ray Diffraction of Iron Containing Samples : The Importance of a Suitable Configuration
Mos, Yvonne M. ; Vermeulen, Arnold C. ; Buisman, Cees J.N. ; Weijma, Jan - \ 2018
Geomicrobiology Journal 35 (2018)6. - ISSN 0149-0451 - p. 511 - 517.
Fluorescence - iron - radiation type - X-ray diffraction
In X-ray diffraction, a good combination of configuration and sample is essential. Copper radiation for iron containing materials leads to a high background. Although this has been recognized, many researchers still use this combination. To clearly show the unsuitability of copper radiation for iron oxides, magnetite, goethite, maghemite, and hematite were analysed in different configurations using copper or cobalt radiation. Results show effects of fluorescence repressing measures and different radiation sources. Copper radiation diffractograms make phase identification contestable. Studies using copper radiation for iron oxides must therefore be carefully evaluated. Cobalt radiation yielded high quality diffractograms, making phase identification unambiguous.
Aspergillus niger N402 derivatives grown with different amounts of iron in the medium
Odoni, D.I. ; Gaal, Merlijn van; Schonewille, T. ; Tamayo Ramos, J.A. ; Martins dos Santos, V.A.P. ; Suarez Diez, M. ; Schaap, P.J. - \ 2017
PRJEB20746 - ERP022924 - Aspergillus niger - iron
Aspergillus niger N402 derivatives were grown with either no iron added to the medium, or 10g/L Fe(II)SO4 added to the medium.
Voorkomen vochtschokken beste remedie om bladrandjes te vermijden
Voogt, Wim - \ 2016
horticulture - greenhouse horticulture - vegetables - tomatoes - plant disorders - calcium absorption - nutrient accounting system - chlorine - iron - climatic factors - illumination - nutrient solutions - moisture - agricultural research
Hergebruik drinkwaterslib beoogt natuurontwikkeling op fosfaatrijke gronden
Dorland, E. ; Fujita, Y. ; Chardon, W.J. ; Lucassen, E.C.H.E.T. ; Smolders, A. ; Ketelaar, R. ; Jong, A.L. de - \ 2016
Vakblad Natuur Bos Landschap (2016)124. - ISSN 1572-7610 - p. 3 - 5.
natuurontwikkeling - drinkwater - slib - fosfaat - bodemverbeteraars - natuurbeheer - afvalhergebruik - veldproeven - ijzer - nature development - drinking water - sludges - phosphate - soil conditioners - nature management - waste utilization - field tests - iron
Natuurbeheerders zitten soms in hun maag met percelen die vanwege hun landbouwkundig verleden een hoge fosfaatlast kennen, omdat dit de ontwikkeling van waardevolle natuur belemmert. Afgraven is duur, uitmijnen tijdrovend, maar wat dan? Kan hergebruik van ijzerrijk drinkwaterslib uitkomst bieden? De eerste resultaten van veldproeven met dit restproduct van drinkwaterwinning zijn hoopgevend.
Recirculatie bij Phalaenopsis technisch goed haalbaar : Investeringsdrempel voor hergebruik drainwater ligt hoog
Arkesteijn, Marleen ; Kromwijk, J.A.M. - \ 2016
Onder Glas 13 (2016)1. - p. 9 - 11.
tuinbouw - glastuinbouw - waterbeheer - potplanten - drainagewater - hergebruik van water - phalaenopsis - gewaskwaliteit - emissiereductie - normen - stikstof - mest - natrium - zink - ijzer - horticulture - greenhouse horticulture - water management - pot plants - drainage water - water reuse - crop quality - emission reduction - standards - nitrogen - manures - sodium - zinc - iron
Hergebruik van drainwater bij phalaenopsis heeft geen nadelige effecten voor de plantengroei. Dat is de eindconclusie uit het onderzoek dat het afgelopen jaar is uitgevoerd en dat de gewascoöperatie Potorchidee deels financierde. De gewascoöperatie is tevreden en wil het komende jaar een vervolgonderzoek naar het effect van gecontroleerd vrijkomende meststoffen. Hiermee kunnen ook niet recirculerende telers een stap zetten.
Iron is essential for photosynthesis and respiration : iron deficiency : the most common deficiency disorder
Heuvelink, E. ; Kierkels, T. - \ 2016
In Greenhouses : the international magazine for greenhouse growers 5 (2016)1. - ISSN 2215-0633 - p. 48 - 49.
horticulture - greenhouse horticulture - rosaceae - chelates - ph - iron - deficiency - plant disorders - crop production - tuinbouw - glastuinbouw - chelaten - ijzer - deficiëntie - afwijkingen, planten - gewasproductie

Iron plays a major role in photosynthesis. That’s why a shortage directly affects the production capacity of the plant. The application of chelates has made iron much more easy to absorb. Nevertheless it’s an element that we have to keep an eye on.
IJzerrijk drinkwaterslib en verschraling landbouwgronden: een proof of principle
Lucassen, E.C.H.E.T. ; Chardon, W.J. ; Dorland, E. ; Sluys, M.L. van der; Poelen, M.D.M. ; Smolders, Alfons J.P. - \ 2015
Landschap : tijdschrift voor Landschapsecologie en Milieukunde 32 (2015)4. - ISSN 0169-6300 - p. 160 - 169.
fosfaat - bodemverbeteraars - ijzer - waterstand - natuurontwikkeling - bodemchemie - slib - phosphate - soil conditioners - iron - water level - nature development - soil chemistry - sludges
Bij de inrichting van het Natuurnetwerk Nederland en van Natura 2000-gebieden worden op grote schaal landbouwgronden heringericht als soortenrijke natuur. Om op korte termijn fosfaatarme bodemcondities te krijgen wordt op locaties waar de bodem te rijk is via maaibeheer en/of uitmijnen te bereiken, vaak gekozen voor verwijdering van de fosfaatrijke bodemlaag. Een mogelijk alternatief voor ontgronden is het toedienen van ijzerslib. Dit restproduct van drinkwaterwinning verbetert de fosfaatbinding van de bodem.
Fonio (Digitaria exilis) in West Africa: towards improving nutrient quality
Koreissi, Y. - \ 2015
University. Promotor(en): Michael Zimmermann, co-promotor(en): Inge Brouwer; Diego Moretti. - Wageningen : Wageningen University - ISBN 9789462574557 - 177
digitaria exilis - digitaria - voedingsstoffenverbetering - voedselkwaliteit - voedingswaarde - ijzer - zink - west-afrika - nutrient improvement - food quality - nutritive value - iron - zinc - west africa

Fonio (Digitaria exilis) in West Africa: Towards improving nutrient quality

Abstract

Hidden hunger affects a far greater percentage of the world’s population with iron and zinc deficiencies being the most common, particularly affecting women of reproductive age. The primary cause of the mineral and vitamin deficiencies in developing countries is inadequate intakes of multiple and bioavailable micronutrients in common cereal-based diets, emphasizing the need for increased quality of diets. Plant genetic diversity, and also indigenous foods and/ or traditional grains as fonio may play a critical role in reduction of the problem for resource poor populations. Fonio (Digitaria exilis) is the most ancient West African cereal representing a key crop in food supply during crop shortfall periods. However, less is known about its potential to contribute improving nutrition and health. In this context, the thesis investigated whether we could improve the nutrient quality of fonio, especially iron, to potentially contribute to the daily intake of population.

Investigations in this thesis comprised: i) the consumption pattern of fonio and its contribution to nutrient intakes (108 women aged 15‐49 year-old selected from 3‐stage cluster sampling procedure in Bamako, Mali for the purpose of the fonio project); ii) the validation of the Mali food composition database (TACAM) for assessing population level intakes of energy and nutrients (36 women out of 108 previously selected); iii) the genetic diversity, nutrient content especially bioavailable iron and zinc content and the effect of processing on fonio landraces (12 fonio landraces collected from farmers in Mali); iv) the sensory variability among fonio landraces (20 fonio landraces collected from farmers in Mali, Guinea and Burkina Faso); v) improved food processing combining dephytinisation with native phytase and fortification of fonio diet with iron to increase iron absorption (16 women aged 18-30 year-old from simple random sampling in Cotonou, Benin).

The results indicated that i) fonio is consumed one to three times/ month by 68% of our study population. The average daily portion size is 152g when consumed. Only 5% of the study population consumed fonio dishes contributing to 16% of the daily energy intake for the consumed portion size, reflecting the low consumption of fonio related to significant barriers such as availability of cooked fonio in urban markets, lack of consistent supply throughout the year, difficult post- harvest processing, high-quality product demand, hard texture coupled with time consuming cooking process, and high cost of fonio products.

The use of the adjusted TACAM is acceptable for estimating average intake at population level for macronutrients, calcium and zinc in a low intake population, but not for carbohydrate and iron intakes which was underestimated and vitamin A which was overestimated, nor for probability of adequate intakes and nutrient densities. At individual level, significant differences were observed between estimated and analyzed intakes for all the nutrients increasing with higher intakes.

The nutrient content of fonio landraces in Mali and the effect of processing of the nutrient values revealed i) a limited genetic variation of studied landraces, polymorphism level (3.5%) compared to 63% reported for 118 fonio accessions collected in West Africa, three different clusters only for Malians landraces compared to two clusters for Mali, Burkina Faso, Guinea and Benin together; ii) no statistically significant differences between fonio landraces for their iron and zinc content, iii) a high iron and phytate concentration in paddy fonio (35 and 514 mg/100 g dry weight) which reduces considerably with traditional processing, the most important losses occurring during processing from paddy to mid wet fonio (approximately 2 and 129 mg/100 g), 96% reduction for iron and 75% for phytate.

Fonio landraces in West Africa were different for their visual (colour and presence/absence of impurities) and their textural (consistency of cooked grain) charactersitics.

Exploring processing to increase iron biavailability from fonio meals confirm that whole wheat flour could be used as a source of natural phytase to produce low phytic acid containing fonio porridge. It showed also that dephytinisation using intrinsic wheat phytase reduced phytate-to-iron molar ratio from 23.7:1 to 2.7:1 after only 1 hour of incubation at 50ºC with pH of 5.0, and iron fortification decreased the molar ratio to 0.3:1. Dephytinisation with wheat phytase and fortification significantly increased iron absorption ratio from 2.6% to 8.2% in fonio porridges.

From these results, we can conclude that the current contribution of fonio to daily bioavailable iron intake is low due to small portion sizes being consumed in low frequency, to considerable losses during processing to mid-wet fonio, and to a high phytate-iron molar ratio. Fonio landraces from Mali, Guinea and Burkina Faso are variable in visual and textural characteristics (colour, presence of impurity and consistency of the cooked grain, respectively), determining the preference of consumers. Selecting landraces for preferred sensory properties may offer an entry point for processors who intend to promote the consumption of fonio and increase its role in diet. In absence of meaningful genetic diversity and variation in iron content in fonio landraces in Mali, there is little benefit in selecting landraces for natural high iron content. Dephytinisation using intrinsic wheat phytase could be a promising processing practice to improve iron bioavailability and fortification is required to increase the amount of absorbed iron from fonio meals.

Impact of a novel protein meal on the gastrointesinal microbiota and host transciptome of larval zebrafish Danio rerio
Rurangwa, E. ; Sipkema, D. ; Kals, J. ; Veld, M. ter; Forlenza, M. ; Bacanu, G.M. ; Smidt, H. ; Palstra, A.P. - \ 2015
Frontiers in Physiology 6 (2015). - ISSN 1664-042X - 27 p.
large gene lists - intestinal microbiota - gut microbiota - digestive physiology - solea-senegalensis - metal uptake - sp-nov - fish - expression - iron
Larval zebrafish was subjected to a methodological exploration of the gastrointestinal microbiota and transcriptome. Assessed was the impact of two dietary inclusion levels of a novel protein meal (NPM) of animal origin (ragworm Nereis virens) on the gastrointestinal tract (GIT). Microbial development was assessed over the first 21 days post egg fertilisation (dpf) through 16S rRNA gene-based microbial composition profiling by pyrosequencing. Differentially expressed genes in the GIT were demonstrated at 21 dpf by whole transcriptome sequencing (mRNAseq). Larval zebrafish showed rapid temporal changes in microbial colonization but domination occurred by one to three bacterial species generally belonging to Proteobacteria and Firmicutes. The high iron content of NPM may have led to an increased relative abundance of bacteria that were related to potential pathogens and bacteria with an increased iron metabolism. Functional classification of the 328 differentially expressed genes indicated that the GIT of larvae fed at higher NPM level was more active in transmembrane ion transport and protein synthesis. mRNAseq analysis did not reveal a major activation of genes involved in the immune response or indicating differences in iron uptake and homeostasis in zebrafish fed at the high inclusion level of NPM
Total dietary antioxidant capacity, individual antioxidant intake and breast cancer risk: The Rotterdam study
Pantavos, A. ; Ruiter, R. ; Feskens, E.J.M. ; Keyser, C.E. de; Hofman, A. ; Stricker, B.H.C. ; Franco, O.H. ; Kiefte-de Jong, J.C. - \ 2015
International Journal of Cancer 136 (2015)9. - ISSN 0020-7136 - p. 2178 - 2186.
prospective cohort - swedish women - vitamin-c - receptor status - pooled analysis - carotenoids - coffee - fruits - iron - tea
Some studies suggest a favorable role of antioxidants on breast cancer risk but this is still inconclusive. The aim of this study was to assess whether overall dietary antioxidant capacity, as assessed by dietary ferric reducing antioxidant potential (FRAP), and individual dietary antioxidant intake were associated with breast cancer risk. Data was used from women participating in the Rotterdam Study, a prospective cohort study among subjects aged 55 years and older (N¿=¿3,209). FRAP scores and antioxidant intake (i.e., vitamin A, C, E, selenium, flavonoids and carotenoids) was assessed at baseline by a food frequency questionnaire. Incident cases of breast cancer were confirmed through medical reports. During a median follow-up of 17 years, 199 cases with breast cancer were identified. High dietary FRAP score was associated with a lower risk of breast cancer [hazard ratio (HR): 0.68; 95% confidence intervals (CI): 0.49, 0.96]. No overall association between individual antioxidant intake and breast cancer risk was found. However, low intake of alpha carotene and beta carotene was associated with a higher risk of breast cancer among smokers (HR: 2.48; 95% CI: 1.21, 5.12 and HR: 2.31; 95% CI: 1.12, 4.76 for alpha and beta carotene, respectively) and low intake of flavonoids was associated with breast cancer risk in women over the age of 70 (HR: 1.80; 95% CI: 1.09, 2.99). These results suggest that high overall dietary antioxidant capacity is associated with a lower risk of breast cancer. Individual effects of dietary carotenoids and dietary flavonoids may be restricted to subgroups such as smokers and elderly.
Afvangen van fosfaat uit bloembollensector met ijzerzand : Test van maatregelen die fosforemissie verminderen
Chardon, W.J. ; Groenenberg, J.E. ; Jansen, S. ; Buijert, A. ; Talens, R. ; Krol, A.F. - \ 2014
Bodem 24 (2014)6. - ISSN 0925-1650 - p. 20 - 22.
vollegrondsteelt - bloembollen - bodemchemie - emissiereductie - fosfaten - adsorptie - ijzer - bollenstreek - outdoor cropping - ornamental bulbs - soil chemistry - emission reduction - phosphates - adsorption - iron
In het oppervlaktewater van de Bollenstreek is de fosfaatconcentratie veel hoger dan de norm van de Europese Kaderrichtlijn Water. Met ijzerzand, een nevenproduct van drinkwaterproductie, kan fosfaat worden afgevangen. Het hoogheemraadschap van Rijnland heeft drie maatregelen op basis van ijzerzand laten onderzoeken op hun effectiviteit. Welke was de beste?
High Prevalence of Maternal Hypothyroidism Despite Adequate Iodine Status in Indian Pregnant Woman in the First Trimester
Jaiswal, N. ; Boonstra, A. ; Thomas, T. ; Basavaraj, C. ; Sharma, S.K. ; Srinivasan, K. ; Zimmerman, M.B. - \ 2014
Thyroid 24 (2014)9. - ISSN 1050-7256 - p. 1419 - 1429.
school-age-children - thyroid-function - free-thyroxine - subclinical hypothyroidism - urinary iodine - deficiency - risk - postpartum - iron - dysfunction
Background: Iodine requirements are increased during pregnancy to maintain maternal and fetal euthyroidism. There have been recent improvements in iodized salt coverage in India, but whether iodized salt is sufficient to sustain iodine requirements during pregnancy remains uncertain. Our aims were to measure thyroid status in first trimester pregnant women in southern India and assess potential determinants of thyroid function, including iodine status, thyroid autoimmunity, dietary patterns, body weight, and anemia. Methods: This was a cross-sectional study among 334 pregnant women of =14 weeks' gestation, in Bangalore, India. We measured anthropometrics, urinary iodine concentration (UIC), maternal thyroid volume (by ultrasound), and thyroid function. We applied a thyrotropin (TSH) upper limit of 2.5¿mIU/L to classify thyroid insufficiency. Using a questionnaire, we obtained sociodemographic and dietary data, obstetric history, and use of iodized salt and iodine supplements. Results: Among the women, the mean (standard deviation) gestational age was 10.3 (2.5) weeks, 67% were nulliparous, 21% were vegetarian, 19% were anemic, and 23% were overweight or obese. Iodized salt was used by 98% of women, and they were iodine sufficient: median UIC (range) was 184.2¿µg/L (8.1–1152¿µg/L) and all had a normal thyroid volume. However, 18% of the women had thyroid insufficiency: 3.7% had overt hypothyroidism (83% with positive TPO-Ab), 9.2% had subclinical hypothyroidism, and 5.2% had hypothyroxinemia. Women consuming vegetarian diets did not have significantly lower iodine intakes or higher risk of hypothyroidism than those consuming mixed diets, but overweight/obesity and anemia predicted thyroid insufficiency. Conclusion: In this urban population of southern India, pregnant women have adequate iodine status in the first trimester. Despite this, many have thyroid insufficiency, and the prevalence of overt hypothyroidism is more than fivefold higher than reported in other iodine sufficient populations of pregnant women.
Effectiveness of stimulating PCE reductive dechlorination: A step-wise approach
Ni, Z. ; Smit, M.P.J. ; Grotenhuis, J.T.C. ; Gaans, P. van; Rijnaarts, H.H.M. - \ 2014
Journal of Contaminant Hydrology 164 (2014). - ISSN 0169-7722 - p. 209 - 218.
chlorinated solvents - natural attenuation - redox conditions - field-scale - iron - tetrachloroethene - groundwater - lactate - acetate - trichloroethylene
Reductive dechlorination of tetrachloroethene (PCE) and its daughter products in aquifers is often hampered by Fe(III) reducing conditions. Rigorous treatment to adjust the redox potential and stimulate dechlorination may be costly and potentially have negative effects on other aquifer functions. A step-wise experimental strategy was applied to investigate the effectiveness of various adjustment scenarios. Batch experiments with ascorbic acid (AA) and sodium lactate (SL) showed that 75 µmol electron equivalents per gram dry mass of aquifer material was required to reach a sufficiently low redox potential for the onset of PCE dechlorination. Similar effects of either AA or SL on the measured redox potential suggest electron donors are not specific. However, the relative rates of Fe(III) and sulphate reduction appeared to be specific to the electron donor applied. While redox potential stabilised around - 450 mV after titration and sulphate was reduced to zero in both treatments, in the AA treatment a faster production of Fe2 + was observed with a final concentration of 0.46 mM compared to only 0.07 mM in the SL treatment. In subsequent batch experiments with aquifer material that was pre-treated with AA or SL, PCE reductive dechlorination occurred within 30 days. Further stimulation tests with extra electron donor or inoculum revealed that adding electron donor can accelerate the initiation of PCE biodegradation. However, bioaugmentation with dechlorinating bacteria is required to achieve complete reductive dechlorination to ethene. The findings from step-wise approaches are relevant for improving the cost-effectiveness of the design and operation of in-situ bioremediation at initially unfavourable environmental conditions.
Influence of pH on the redox chemistry of metal (hydr)oxides and organic matter in paddy soils
Pan, Y. ; Koopmans, G.F. ; Bonten, L.T.C. ; Song, J. ; Luo, Y. ; Temminghoff, E.J.M. ; Comans, R.N.J. - \ 2014
Journal of Soils and Sediments 14 (2014)10. - ISSN 1439-0108 - p. 1713 - 1726.
flooded soil - ion-binding - cadmium - iron - speciation - manganese - reduction - sorption - dynamics - mobilization
The primary purpose of this study was to determine how flooding and draining cycles affect the redox chemistry of metal (hydr)oxides and organic matter in paddy soils and how the pH influences these processes. Our secondary purpose was to determine to what extent a geochemical thermodynamic equilibrium model can be used to predict the solubility of Mn and Fe during flooding and draining cycles in paddy soils. We performed a carefully designed column experiment with two paddy soils with similar soil properties but contrasting pH.We monitored the redox potential (Eh) continuously and took soil solution samples regularly at four depths along the soil profile during two successive flooding and drainage cycles. To determine dominant mineral phases of Mn and Fe under equilibrium conditions, stability diagrams of Mn and Fe were constructed as a function of Eh and pH. Geochemical equilibrium model calculations were performed to identify Mn and Fe solubility-controlling minerals and to compare predicted total dissolved concentrations with their measured values. Flooding led to strong Eh gradients in the columns of both soils. In the acidic soil, pH increased with decreasing Eh and vice versa, whereas pH in the alkaline soil was buffered by CaCO3. In the acidic soil, Mn and Fe solubility increased during flooding due to reductive dissolution of their (hydr)oxides and decreased during drainage because of re-oxidation. In the alkaline soil, Mn and Fe solubility did not increase during flooding due to Mn(II) and Fe(II) precipitation as MnCO3, FeCO3, and FeS. The predicted levels of soluble Mn and Fe in the acidic soil were much higher than their measured values, but predictions and measurements were rather similar in the alkaline soil. This difference is likely due to kinetically limited reductive dissolution of Mn and Fe (hydr)oxides in the acidic soil. During flooding, the solubility of dissolved organic matter increased in both soils, probably because of reductive dissolution of Fe (hydr)oxides and the observed increase in pH. Conclusions Under alternating flooding and draining conditions, the pH greatly affected Mn and Fe solubility via influencing either reductive dissolution or carbonate formation. Comparison between measurements and geochemical equilibrium model predictions revealed that reductive dissolution of Mn and Fe (hydr)oxides was kinetically limited in the acidic soil. Therefore, when applying such models to systems with changing redox conditions, such rate-limiting reactions should be parameterized and implemented to enable more accurate predictions of Mn and Fe solubility.
Safety and efficacy of iron supplementation in pregnant Kenyan women
Mwangi, M.N. - \ 2014
University. Promotor(en): Huub Savelkoul; A.M. Prentice, co-promotor(en): Hans Verhoef. - Wageningen : Wageningen University - ISBN 9789461739209 - 220
ijzer - minerale supplementen - veiligheid - risicoschatting - werkzaamheid - zwangerschap - kenya - iron - mineral supplements - safety - risk assessment - efficacy - pregnancy

Since the British doctor Ronald Ross received the 1902 Nobel Prize in medicine for his work on malaria, more people have died from the disease than all world wars combined. This is in spite of the fact that the French chemists Pierre Joseph Pelletier and Joseph Bienaimé Caventou made quinine available from as early as 1820. According to the World Health Organisation (WHO), there were about 219 million cases of malaria in 2010 and an estimated 660,000 deaths majority of which (80% of cases and 90% of deaths) were in Africa.

Of almost two billion people who are anaemic globally, 41.8% are pregnant women. Iron supplements are used to prevent anaemia. There are concerns that iron given in high doses may increase malaria rates. Uncertainties regarding the safety of iron supplementation in malaria endemic regions were propelled by a randomized controlled trial that evaluated the effects of iron and folic acid supplementation in 32,155 children in Pemba, Tanzania. This study found that children who received iron and folic acid supplements were more likely to die or to need hospitalisation for an adverse event. At the same time, malaria is known to exacerbate anaemia; an almost inevitable consequence of malarial infection. As such, the safety of daily oral use of iron supplements by pregnant women, as a public health intervention is still not clearly established; at least not until publication of our main findings.

This thesis assessed the effects of iron supplementation on safety indicators, and on iron status, in pregnant women and their neonates. Several preparatory activities were carried out, including a census of the population in the study area and a pilot study to check the operability of the study protocols. A main study was designed with the hypothesis that consumption of food products fortified with iron combined with intake of iron supplements especially in pregnancy, would be detrimental to the health of pregnant women and their neonates.

The objectives of the study were: 1) to compare the presence of malarial infection in parturient women who received a combination of iron-fortified foods with iron supplements versus iron-fortified foods only; 2) to assess intervention effects on the maternal prevalence of iron deficiency anaemia at 1 month after delivery; 3) to assess intervention effects on neonatal iron stores at 1 month of age; 4) to assess the diagnostic utility of Zinc protoporphyrin (ZPP) in diagnosing iron deficiency in malaria endemic regions; 5) to identify baseline factors that are prognostic for the Non-Transferrin Bound Iron (NTBI) response to consumption of a single iron supplement; 6) to determine the factors that predict Plasmodium infection in pregnancy; 7) to identify factors associated with birth weight; 8) to develop a methodology to predict cases of low birth weight, using a single prognostic score that is based on prognostic variables collected at the second trimester of pregnancy; and 9) to develop methods for community-based flour fortification with iron.

Most countries have enacted, or are in the process of enacting legislation for mandatory fortification of flour with iron. Thus pregnant women may receive iron from fortified foods and from universal iron supplementation programmes. This thesis provides answers to pertinent questions regarding the safety and efficacy of iron supplementation by comparing daily high-dose iron (i.e. iron-fortified foods plus iron supplements) versus low-dose iron (i.e. iron-fortified foods only) during pregnancy. The main outcome measure was the presence of maternal Plasmodium infection at birth, regardless of species. Chapter 1 is a detailed introduction of the background to the study and the design of the study.

This thesis presents concrete evidence that iron supplementation to pregnant women in a highly malaria endemic region does not result in increased risk of malarial infection; percent difference (95%CI) = 0.0% (─9.3% to 9.3%). Programme implementers and governments in malaria endemic regions should not be held back by previous recommendations that cautioned against issuing iron supplements to pregnant women. In light of these findings, there is no need to first screen for malaria before giving iron supplements.

Iron supplementation had major benefits for mothers and their neonates (chapter 2). The findings reported in this thesis showed a mean increase in birth weight of 143 g relative to the low-dose iron group. The effects of iron were influenced by the participants initial iron status. Correction of iron deficiency increased birth weight by 249 g, even though we cannot exclude the possibility that this may have increased malarial infection by 10%. There was no evidence that effects of iron on birth weight were influenced by intermittent preventive treatment against malaria. Iron supplementation also increased fetal growth by 0.27 SD, 95%CI: (0.04 to 0.50) probably as a result of gains in length and weight for gestation age.

We also showed improved neonatal iron stores one month post-partum as indicated by a 17.1 % (95% CI: 2.0% to 34.3%) increase in plasma ferritin concentration in neonates of mothers who received high-dose iron compared to those who received low-dose iron. This provides more impetus to the need to offer iron supplements to pregnant women with the aim of boosting infant iron stores (chapter 2).

ZPP was found to be of unreliable diagnostic utility when discriminating between pregnant women with and without iron deficiency in regions where chronic diseases are prevalent (chapter 3). The current conventional cut off points for whole blood ZPP e.g. >70 μmol/mol heme, can result in gross estimates of the prevalence of iron deficiency especially if the true prevalence is low.

The appearance of non-transferrin bound iron (NTBI) in circulation after oral ingestion of iron supplements has been thought to aid the growth and multiplication of Plasmodium parasites thereby increasing malaria induced morbidity and mortality. We did not observe any increase in NTBI concentrations three hours after oral ingestion of 60 mg of ferrous fumarate (Chapter 4). We cannot exclude the possibility that iron supplementation leads to NTBI production when supplements are not consumed with food, because the lunch meal consumed by majority of our participants during the 3-hour waiting period probably contained natural compounds (phytates) that may have limited an NTBI response.

In chapter 5 of this thesis, we aimed to develop a field friendly tool that can be used to predict asymptomatic Plasmodium infection. This was motivated by the fact that most point-of-care dipstick tests used to detect Plasmodium infection are not able to detect 100% of all the infection present yet asymptomatic infections are increasingly associated with adverse maternal and neonatal outcomes. Although many likely predictive factors were assessed individually or in combination with others, we did not succeed in developing a reliable tool that is easy to apply in resource-poor malaria endemic settings.

In Chapter 6, we aimed to identify factors associated with birth weight and to develop a methodology to predict cases of low birth weight using a single prognostic score that is based on prognostic variables collected at the second trimester of pregnancy. Factors that were found to be independently associated with reduced birth weight were being never married, inflammation, being a girl, and iron deficiency. Being overweight was associated with increased birth weight. The results indicate that we can use variables collected rapidly and at relatively low cost and ease to identify with fair accuracy women in the second trimester of pregnancy who are at high risk of giving birth to a neonate with low birth weight.

The various aspects of the work presented in this thesis including the implications for policy makers are discussed in chapter 7. For policy makers, the findings of this thesis are a welcome relief. The findings therein eliminate all doubt that has hitherto been associated with antenatal iron supplementation in malaria endemic areas. Most countries already have iron supplementation policies that are well aligned to the World Health Organisation policies. Efforts to widen the coverage of antenatal iron supplementation especially in malaria endemic regions should be urgently scaled up. However, the evidence provided in this thesis is only applicable to pregnant women and cannot be extrapolated to children in malaria endemic regions. For this population, the current WHO policy must be used thus before iron supplementation, children must first be screened for malaria.

Although this thesis provides answers to key scientific questions that have hitherto baffled the scientific community, there are still research questions that can be clarified further. The effects of a high iron dose in pregnancy (as per national and international guidelines, the daily supplementation dose for pregnant women should be doubled to 120 mg iron if they are anaemic or if 6 months duration cannot be achieved in pregnancy (Chapter 2)) on maternal and neonatal outcomes need to be elucidated. Further research is needed in order to describe fully, the NTBI response to consumption different types and amounts of oral iron supplements. There is urgent need for diagnostic tools that can be used in resource-poor settings to diagnose asymptomatic infections. Further research in children is needed to provide evidence of the safety and efficacy of iron supplementation in malaria endemic regions and to assess the diagnostic performance of zinc protoporphyrin in children. In addition, since our studies suggest that screening based on Hb concentration as now practiced in many countries, is inaccurate in discriminating between women at high and low risk of delivering neonates with low birth weight, further studies are needed to identify appropriate markers and cut-off points that are suited to this purpose.

In conclusion, this thesis has shown that there is no evidence that antenatal iron supplementation increases Plasmodium infection. Antenatal iron supplementation leads to large improvements in birth weight, fetal growth and infant iron stores, with potentially immense benefits for infant survival and health that should outweigh any possible concerns about risks of malaria. Epidemiological calculations indicate that if our results are applied to all women in developing countries in order to eliminate iron deficiency, we could avoid 3 million births with low birth weight annually and save the lives of more than half a million neonates. Scaling up universal iron supplementation in pregnancy in developing countries will generate major public health gains.

From the Environment to the Host: Re-Wiring of the Transcriptome of Pseudomonas aeruginosa from 22°C to 37°C
Barbier, M. ; Damron, F.H. ; Bielecki, P. ; Suarez Diez, M. ; Puchalka, J. ; Albertí, S. ; Martins Dos Santos, V.A.P. ; Goldberg, J.B. - \ 2014
PLoS One 9 (2014)2. - ISSN 1932-6203
temperature-dependent transcriptome - growth temperature - anaerobic regulation - regulatory protein - genome database - virulence - genes - operon - iron - expression
Pseudomonas aeruginosa is a highly versatile opportunistic pathogen capable of colonizing multiple ecological niches. This bacterium is responsible for a wide range of both acute and chronic infections in a variety of hosts. The success of this microorganism relies on its ability to adapt to environmental changes and re-program its regulatory and metabolic networks. The study of P. aeruginosa adaptation to temperature is crucial to understanding the pathogenesis upon infection of its mammalian host. We examined the effects of growth temperature on the transcriptome of the P. aeruginosa PAO1. Microarray analysis of PAO1 grown in Lysogeny broth at mid-exponential phase at 22°C and 37°C revealed that temperature changes are responsible for the differential transcriptional regulation of 6.4% of the genome. Major alterations were observed in bacterial metabolism, replication, and nutrient acquisition. Quorum-sensing and exoproteins secreted by type I, II, and III secretion systems, involved in the adaptation of P. aeruginosa to the mammalian host during infection, were up-regulated at 37°C compared to 22°C. Genes encoding arginine degradation enzymes were highly up-regulated at 22°C, together with the genes involved in the synthesis of pyoverdine. However, genes involved in pyochelin biosynthesis were up-regulated at 37°C. We observed that the changes in expression of P. aeruginosa siderophores correlated to an overall increase in Fe(2+) extracellular concentration at 37°C and a peak in Fe(3+) extracellular concentration at 22°C. This suggests a distinct change in iron acquisition strategies when the bacterium switches from the external environment to the host. Our work identifies global changes in bacterial metabolism and nutrient acquisition induced by growth at different temperatures. Overall, this study identifies factors that are regulated in genome-wide adaptation processes and discusses how this life-threatening pathogen responds to temperature
The influence of spatiotemporal variability and adaptations to hypoxia on empirical relationships between soil acidity and vegetation
Cirkel, D.G. ; Witte, J.P.M. ; Bodegom, P.M. van; Nijp, J.J. ; Zee, S.E.A.T.M. van der - \ 2014
Ecohydrology 7 (2014)1. - ISSN 1936-0584 - p. 21 - 32.
bodemchemie - bodemaciditeit - vegetatietypen - bodem-plant relaties - soortensamenstelling - plantenfysiologie - rizosfeer - wetlands - heterogeniteit - ecohydrologie - ruimtelijke variatie - soil chemistry - soil acidity - vegetation types - soil plant relationships - species composition - plant physiology - rhizosphere - heterogeneity - ecohydrology - spatial variation - ellenberg indicator values - field-measurements - plant ecology - ph changes - iron - regression - diversity - diffusion - oxidation
Soil acidity is well known to affect the species composition of natural vegetation. The physiological adaptations of plants to soil acidity and related toxicity effects and nutrient deficiencies are, however, complex, manifold and hard to measure. Therefore, generally applicable quantifications of mechanistic plant responses to soil acidity are still not available. An alternative is the semi-quantitative and integrated response variable ‘indicator value for soil acidity’ (Rm). Although relationships between measured soil pH and Rm from various studies are usually strong, they often show systematic bias and still contain high residual variances. On the basis of a well-documented national dataset consisting of 91 vegetation plots and a dataset with detailed, within-plot, pH measurements taken at three periods during the growing season, it is shown that strong spatiotemporal variation of soil pH can be a critical source of systematic errors and statistical noise. The larger part of variation, however, could be explained by the moisture status of plots. For instance, Spearman's rho decreased from 93% for dry plots and 87% for moist plots to 59% for wet plots. The loss of relation between soil pH and Rm in the moderately acid to alkaline range at increasingly wetter plots is probably due to the establishment of aerenchyma-containing species, which are able to control their rhizosphere acidity. Adaptation to one site factor (oxygen deficit) apparently may induce indifference for other environmental factors (Fe2+, soil pH). For predictions of vegetation response to soil acidity, it is thus important to take the wetness of plots into account
Sterke vermindering van fosfaatuitspoeling uit landbouwgronden met de fosfaatbindende drain
Groenenberg, J.E. ; Chardon, W.J. ; Koopmans, G.F. - \ 2013
draineerbuizen - drainagewater - ijzer - adsorptie - waterkwaliteit - fosfaten - veldproeven - drain pipes - drainage water - iron - adsorption - water quality - phosphates - field tests
Voor gedraineerde landbouwgronden (meer dan 50% in Nederland) heeft Alterra de fosfaatbindende drain ontwikkeld. Dit is een normale buisdrain die is ingebed in ijzerzand. De omhulling met ijzerzand bindt het fosfaat uit het fosfaatrijke water voor het de drainbuis instroomt. Het schone water wordt afgevoerd naar het oppervlaktewater.
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