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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Molecular assessment of muscle health and function : The effect of age, nutrition and physical activity on the human muscle transcriptome and metabolom
Hangelbroek, Roland W.J. - \ 2017
Wageningen University. Promotor(en): A.H. Kersten; C.P.G.M. de Groot, co-promotor(en): M.V. Boekschoten. - Wageningen : Wageningen University - ISBN 9789463437103 - 205
muscles - age - nutrition - physical activity - transcriptomes - metabolomes - elderly - creatine - phosphocreatine - vitamin d - atrophy - spieren - leeftijd - voeding - lichamelijke activiteit - transcriptomen - metabolomen - ouderen - creatine - fosfocreatine - vitamine d - atrofie

Prolonged lifespan and decreased fertility will lead to an increased proportion of older adults in the world population (population aging). An important strategy to deal with population aging has been to promote healthy aging; not only to prevent mounting health care costs, but also to maintain independence and quality of life of older populations for as long as possible. Close to the opposite of the healthy aging is frailty. A major component of (physical) frailty is sarcopenia: age-related loss of muscle mass. Decreased muscle size and strength has been associated with a wide variety of negative health outcomes, including increased risk of hospitalization, physical disability and even death. Therefore, maintaining muscle size and strength is very important for healthy aging. Nutrition and physical activity are possible strategies to maintain or even improve muscle function with age.

The effect of nutrition, age, frailty and physical activity on the function of skeletal muscle is complex. A better understanding of the molecular mechanisms involved can provide new insights in potential strategies to maintain muscle function over the life course. This thesis aims to investigate these mechanisms and processes that underlie the effects of age, frailty and physical activity by leveraging the sensitivity and comprehensiveness of transcriptomics and metabolomics.

Chapter 2 and 3 describe the effects of age, frailty and resistance-type exercise training on the skeletal muscle transcriptome and metabolome. Both the transcriptome and metabolome show significant differences between frail and healthy older adults. These differences are similar to the differneces between healthy young men and healthy older adults, suggesting that frailty presents itself as a more pronounced form of aging, somewhat independent of chronological age. These age and frailty related differences in the transcriptome are partially reversed by resistance-type exercise training, in accordance with the observed improvement in muscle strength. Regression analysis revealed that the protocadherin gamma gene cluster may be important to skeletal muscle function. Protocadherin gamma is involved in axon guidance and may be upregulated due to the denervation-reinnervation cycles observed in skeletal muscle of older individuals. The metabolome suggested that resistance-type exercise training led to a decrease in branched-chain amino acid oxidation, as shown by a decrease in amino acid derived carnitines. Lastly, the blood metabolome showed little agreement with the metabolome in skeletal muscle, indicating that blood is a poor read-out of muscle metabolism.

We assessed the effect of knee immobilization with creatine supplementation or placebo on the skeletal muscle transcriptome and metabolome in chapter 4. Knee immobilization caused muscle mass loss and strength loss in all participants, with no differences between creatine and placebo groups. Knee immobilization appeared to induce the HDAC4-myogenin axis, which is primarily associated with denervation and motor neuron diseases. The metabolome showed changes consistent with the decreased expression of energy metabolism genes. While acyl-carnitine levels tended to decrease with knee immobilization, one branched-chain amino acid-derived acyl carnitine was increased after knee immobilization, suggesting increased amino acid oxidation.

Vitamin D deficiency is common among older adults and has been linked to muscle weakness. Vitamin D supplementation has been proposed as a strategy to improve muscle function among older populations. In chapter 5, supplementation with vitamin D (calcifediol, 25(OH)D) is investigated as nutritional strategy to improve muscle function among frail older adults. However, we observed no effect of vitamin D on the muscle transcriptome. These findings indicate the effects of vitamin D supplementation on skeletal muscle may be either absent, weak, or limited to a small subset of muscle cells.

Transcriptomic changes due to different forms of muscle disuse are compared in chapter 6 (primarily knee immobilization and bed rest). The goal was to determine the similarities and differences among various causes of muscle atrophy in humans (primarily muscle disuse). Both knee immobilization and bed rest led to significant changes in the muscle transcriptome. However, the overlap in significantly changed genes was relatively small. Knee immobilization was characterized by ubiquitin-mediated proteolysis and induction of the HDAC4/Myogenin axis, whereas bed rest revealed increased expression of genes of the immune system and increased expression of lysosomal genes. Knee immobilization showed the highest similarity with age and frailty-related transcriptomic changes. This finding suggests that knee immobilization may be the most suitable form of disuse atrophy to assess the effectiveness of strategies to prevent age-related muscle loss in humans.

The transcriptome and metabolome are incredibly useful tools in describing the wide array of biological systems within skeletal muscle. These systems can be modulated using physical activity (or lack thereof) as well as nutrition. This thesis describes some of these processes and highlights several unexplored genes and metabolites that may be important for maintaining or even optimizing muscle function. In the future, it may be possible to optimize both exercise and nutrition for each individual using these techniques; or even better, cheaper and less invasive alternatives.

More food, lower footprint : How circular food production contributes to efficiency in the food system
Scholten, M.C.T. - \ 2017
Wageningen : Wageningen University & Research
biobased economy - biobased chemistry - cycling - environment - sustainability - nutrition - biomass - renewable energy - residual streams - agricultural wastes - organic wastes - crop residues - food production - chemie op basis van biologische grondstoffen - kringlopen - milieu - duurzaamheid (sustainability) - voeding - biomassa - hernieuwbare energie - reststromen - agrarische afvalstoffen - organisch afval - oogstresten - voedselproductie
Martin Scholten on circular food production. Ideas about how circular food production can contribute to the sustainable food security.
Evaluation of dietary intake and nutritional supplement use of elite and sub-elite Dutch athletes : Dutch Sport Nutrition and Supplement Study
Wardenaar, Floris C. - \ 2017
Wageningen University. Promotor(en): Renger Witkamp, co-promotor(en): Marco Mensink; Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789463430326 - 189
food intake - food supplements - athletes - nutrition - sport - dietary guidelines - netherlands - voedselopname - voedselsupplementen - atleten - voeding - sport - dieetrichtlijnen - nederland

Background: Well-trained elite athletes differ from the general population in being considerably more physically active and by other lifestyle characteristics including intensive training routines and periodisation of their training programs. Hence, adequate intake of energy and nutrients is of great importance to this population to ensure optimal performance and recovery during training or competition and also to minimize health risks. A consistent dietary intake pattern, in line with the sport-specific recommendations can be difficult to achieve for this group. The specific recommendations are formulated for nutritional intake during and after training or within competition. However, a large variation is seen in dietary intake by athletes. Therefore, the question arises as to what extent athletes meet recommendations and use nutritional supplements in an optimal manner.

Aims: First, to investigate dietary intake and nutritional supplement use by well-trained Dutch athletes and compare these intakes with recommendations both for the general population and sport nutrition recommendations, which are based on expert consensus. Second, to provide an up-to-date overview of nutrient intake levels in a diverse and relatively large group of Dutch elite and sub-elite athletes practicing sports at the highest competitive level.

Methods: As part of this thesis 24-hour recalls and questionnaires were used to gain insight into dietary intake and nutritional supplement use (n=553). To validate our methods, 24-hour nitrogen urine excretions were obtained in a subsample of our athletic population (n=47). A questionnaire was used to 1) investigate the prevalence of nutritional supplement use in a large sample of the athletic population (n=778) and 2) investigate the prevalence of nutritional supplement use in a large sample of the Dutch general population (n=1544). Finally, food intake during an ultramarathon was monitored (n=4) and questioned using a food frequency questionnaire (n=41).

Results: Our validation study showed that 24-hour recalls and accompanying questionnaires underestimated protein intake in young elite athletes to the same extent as reported for non- athlete populations. Notwithstanding this, the method was considered suitable for ranking athletes according to their protein intake as needed in epidemiological studies. It was found that most athletes were able to meet the estimated average requirement (EAR) for carbohydrate and protein. Regarding sport nutrition recommendations, most of the athletes met protein (1.2 g/kg) but not carbohydrate recommendations (5 g/kg). No major differences in carbohydrate and protein intake were seen between sports categories (i.e. endurance, team and strength athletes). Athletes were at risk of too low intake levels of several micronutrients, especially when they did not use dietary supplements (i.e. vitamin D, vitamin A, vitamin B1 and B2 in men and women, and iron in women), whereas users of supplements showed a slightly elevated risk of intake levels exceeding the upper intake level (UL). This was in particular the case for vitamin B3. Our investigations in ultramarathon runners showed that these athletes did not reach sports nutrition recommendations from their habitual diet. In men and women, habitual mean carbohydrate (CHO) intake was lower than recommended, as was mean protein intake by women. CHO intake during the race was <60 g/h in 75% of the athletes. A large variation in nutrient and fluid intake was seen. This may be related to a high incidence of GI distress (82% of the runners reported GI complaints, but severe GI distress was low). Use of dietary supplements and sport nutrition products in the general population was reported by two-thirds of all respondents. Thirty-three percent reported the use of sport nutrition products. One could question whether the use of these energy containing sport nutrition products fits all respondents’ physical activity needs. Furthermore, it was shown that almost all athletes (97%) have used nutritional supplements some time during their athletic careers. Additionally, receiving dietary counselling seems to result in better choices with respect to nutritional supplement use.

Conclusion: On a population level and with respect to the existing sport nutrition recommendations, nutritional intake in well-trained Dutch competitive athletes was low to moderate for carbohydrate intake and sufficient for protein intake. Suboptimal consumption of micronutrients was reported based on comparison with the estimated average requirement (EAR) for several micronutrients, especially for vitamin D. The use of dietary supplements adds to dietary intake. However, not all athletes consume these types of products, and day to day compliance in supplement users is low. Athletes are advised to focus on the selection of whole food carbohydrate-rich products with a high nutrient density and to consume a large variety of products containing both fat-soluble and water-soluble vitamins. When athletes experience difficulties in following these recommendations, the advice could be to use a low dose multivitamin (50-100% RDA).

Linking growing up and getting old : plastic and evolutionary effects of developmental diet on adult phenotypes and gene expression in the fruit fly
May, C.M. - \ 2016
Wageningen University. Promotor(en): Bas Zwaan, co-promotor(en): Fons Debets. - Wageningen : Wageningen University - ISBN 9789462577633 - 183
drosophila melanogaster - gene expression - nutrition - evolution - diet - lifespan - fecundity - biological development - drosophila melanogaster - genexpressie - voeding - evolutie - dieet - levensduur - voortplantingspotentieel - biologische ontwikkeling
Blijven Bewegen na de BeweegKuur : De rol van groen in de woonomgeving
Vries, S. de; Langers, F. ; Meis, Jessie ; Berendsen, B. ; Kremers, Stef - \ 2016
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2701) - 25 p.
voeding en gezondheid - lichamelijke activiteit - levensstijl - openbaar groen - herstellen - gezondheid - voeding - beweging - welzijn - nutrition and health - physical activity - lifestyle - public green areas - reconditioning - health - nutrition - movement - well-being
De BeweegKuur is een leefstijlinterventie die beoogt blijvend gezonder voedings- en beweeggedrag te
realiseren. Qua beweging is het de bedoeling dat de deelnemers op het eind van de BeweegKuur
uitstromen naar het reguliere beweegaanbod in hun leefomgeving. In deze studie is gekeken of groen
in de woonomgeving een rol speelt bij het volhouden van het beweegniveau tot een jaar na afloop van
de BeweegKuur. Specifiek is gekeken naar a) de rol van groen bij de keuze voor uitstroomactiviteit en
b) die van uitstroomactiviteit op de kans op uitval. Daarnaast is, min of meer los van de activiteit,
gekeken naar c) het volhouden van de mate van lichamelijke activiteit in termen van beweegminuten,
zoals die op het eind van de BeweegKuur bestond.
Voeding blog
Dagevos, H. ; Doets, E.L. ; Groot, C.P.G.M. de; Kremer, S. ; Rest, O. van de; Ruben, R. ; Tieland, C.A.B. ; Zondervan, C. - \ 2015
Wageningen : Wageningen UR
voeding en gezondheid - voedselveiligheid - voedselzekerheid - voedsel - voeding - internet - telecommunicatie - nutrition and health - food safety - food security - food - nutrition - telecommunications
Voeding en voedsel spelen binnen Wageningen UR een centrale rol. In 2040 hebben we 9 miljard mensen te voeden met een veranderende voedselvraag. Hoe moeten we iedereen van gezond voedsel voorzien, zonder schade aan te richten aan het milieu? Voeding bepaalt voor een grote mate onze gezondheid. Het gaat daarbij om veilige voeding, maar ook afgestemd op de behoefte. Wageningse onderzoekers bloggen over het onderzoek naar beide onderwerpen en werkt daarmee aan een betere kwaliteit van leven. Dit blog is een initiatief van Wageningen University and Research Centre. Wageningen UR is het samenwerkingsverband tussen Wageningen University en Stichting DLO. Op dit platform delen onze medewerkers verhalen en kennis over hun werkveld en nodigen u uit om hierover mee te denken.
Could nutrition sensitive cocoa value chains be introduced in Ghana? Report of a brief study that identifies opportunities and bottlenecks
Vries, K. de - \ 2015
Wageningen : Centre for Development Innovation, Wageningen UR (Report CDI / Wageningen UR, Centre for Development Innovation 15-105) - 22
food consumption - households - gender relations - women - cocoa - undernutrition - nutrition - ghana - africa - west africa - voedselconsumptie - huishoudens - man-vrouwrelaties - vrouwen - cacao - ondervoeding - voeding - afrika - west-afrika
This study looks at whether introducing nutrition sensitive cocoa value chains in Ghana is feasible and recommends how this could be done. After establishing the cocoa farming and nutrition context in Ghana, the study zooms in on one cocoa producing sub-district to collect detailed data in order to provide recommendations.
Inequalities in Food Security and Nutrition. A Life Course Perspective
Bras, H. - \ 2015
Wageningen : Wageningen University - ISBN 9789462571891 - 36
voedselzekerheid - voeding - slechte voeding - gezondheidsongelijkheden - honger - levensloop - wereld - food security - nutrition - malnutrition - health inequalities - hunger - life course - world
Alleen sterkere smaak verhoogt eetlust niet
Doets, E.L. ; Kremer, S. - \ 2015
Resource: weekblad voor Wageningen UR 10 (2015)6. - ISSN 1874-3625 - p. 8 - 8.
ondervoeding - eiwitdepletie - ouderen - voedselvoorkeuren - voedselkwaliteit - productontwikkeling - smaak - voedselverpakking - voeding - voedingsonderzoek - ouderenvoeding - undernutrition - protein depletion - elderly - food preferences - food quality - product development - taste - food packaging - nutrition - nutrition research - elderly nutrition
Vijf tot tien procent zelfstandige ouderen is ondervoed. Ouderen waarderen voeding waarschijnlijk beter als verschillende aspecten zoals textuur, smaak en uiterlijk tegelijkertijd worden verbeterd. Dit schrijven Esmée Doets en Stefanie Kramer, onderzoekers bij Food & Biobased Research, in een overzichtsstudie in het tijdschrift Food Quality and Preference.
Varken is goed als model voor suikerpatiënt
Sikkema, A. ; Koopmans, S.J. - \ 2015
Resource: weekblad voor Wageningen UR 10 (2015)1. - ISSN 1874-3625 - p. 8 - 8.
varkens - mensen - metabolisme - voeding - suikerziekte - dieet - voedingsonderzoek - pigs - people - metabolism - nutrition - diabetes - diet - nutrition research
Niet alle dikke mensen zijn ongezond. Dat blijkt uit Wagenings onderzoek dat is gedaan met varkens. Varkens doen het goed als onderzoekmodel om het effect van voeding op onze welvaartsziekten te bepalen. De stofwisseling van mensen en varkens komt namelijk sterk overeen, stelt onderzoeker Sietse Jan Koopmans. Dit artikel gaat hier nader op in.
Effect of iodine supplementation in Indian pregnant women on maternal and newborn thyroid function and cognitive development
Jaikrishna, N. - \ 2015
Wageningen University. Promotor(en): Michael Zimmermann, co-promotor(en): Alida Melse-Boonstra; K Srinivasan. - Wageningen : Wageningen University - ISBN 9789462573338 - 244
jodium - maternale voeding - zwangerschap - voeding - hypothyreoïdie - schildklierziekten - schildklierwerking - jodiumhoudend zout - minerale supplementen - kenvermogen - cognitieve ontwikkeling - mineraaltekorten - voedingsstoffentekorten - iodine - maternal nutrition - pregnancy - nutrition - hypothyroidism - thyroid diseases - thyroid function - iodized salt - mineral supplements - cognition - cognitive development - mineral deficiencies - nutrient deficiencies

ABSTRACT

Background: Iodine is a key nutrient in neurodevelopment, and the fetus is entirely dependent on the iodine intake of the mother to fulfill this important requirement for proper brain function. While this is clearly known, it is uncertain if maternal iodine nutrition should be monitored separately against what is in current practice in public health programs to control iodine deficiency. Also, it is unclear whether it is beneficial to supplement pregnant women with iodine in mild-to moderately iodine deficient and also iodine sufficient areas. Finally, the role of thyroid dysfunction in depression during pregnancy is uncertain.

Objectives: 1) to determine whether iodine supplementation to pregnant women improves maternal and newborn thyroid function, pregnancy outcome, birth weight, infant growth and cognitive performance; 2) to assess iodine intake and potential determinants of intake, in pregnant women and their children who were sharing all meals; 3) to measure thyroid status during pregnancy and assess potential determinants of maternal thyroid function including iodine status, thyroid autoimmunity, body weight and anemia; 4) to assess the association of maternal depression, and thyroid function during pregnancy.

Methods: 1) In a randomized placebo controlled trial (RCT), the MITCH (Maternal Iodine Supplementation and its Effects on Thyroid function and CHild Development) study, pregnant women, gestational age ≤14 weeks, in Bangalore, India, were randomized to receive either a daily supplement of 200 µg oral iodine or placebo from enrolment until delivery. Women were followed through delivery, and then with postnatal follow-up of their infants at 6 weeks, 1 and 2 year. Early neonatal development was assessed using the Neonatal Behavioral Assessment Scale (NBAS) at 6 weeks of age; neurocognitive assessment was done using the Bayley Scales of Infant Development (BSID III) at 1 and 2 years, and BRIEF-P (Behavior Rating Inventory of Executive Function) at 2 years; 2) A cross-sectional study comparing iodine status of pregnant women and their children, who were sharing all meals in Bangalore, India; 3) A cross-sectional study among 334 pregnant women ≤14 weeks of gestation, in Bangalore, India, who were screened for the RCT; 4) Secondary analysis of the longitudinal data on 318 pregnant women in the RCT.

Results: 1) In the RCT, there were no significant differences between groups in maternal thyroid function tests or thyroid volume during gestation. The prevalence of thyroid dysfunction or anti-TPO antibodies did not differ significantly during gestation and postpartum. Postpartum, there were no significant differences between the maternal and infant groups in thyroid function, birth outcomes or UIC. Neonates whose mothers received iodine supplementation during pregnancy had better orientation scores at 6 weeks of age and lower scores of inhibition suggesting better executive function at 2 years of age although neurocognitive development on the BSID III were not significantly different between groups; 2) In the pilot study, a) median UIC in pregnant women was 172 µg/L, b) the median UIC was >150 µg/L in all trimesters and c) thyroid size was not significantly different across trimesters; the median UIC in children was 220µg/L, indicating ‘more than adequate’ iodine intake at this age. Median UIC was significantly higher in children than in their mothers (p=0.008). 3) In the cross-sectional study, 21% women 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 was 184.2 µg/L and all had normal thyroid volume. However, 18% of 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; 4) In the longitudinal study, there was no significant difference in depressive symptoms between the iodine intervention and placebo groups. Women with depressive symptoms had significantly lower serum TSH compared to women without depressive symptoms in the first trimester. Pregnant women with prenatal depressive symptoms had a significantly higher number of medical symptoms.

Conclusion: 1) Iodine supplementation in mildly iodine deficient and in iodine sufficient pregnant women was well-accepted and safe and did not increase the risk of excess iodine intake, hyper- or hypothyroidism, or thyroid autoimmunity. Though there were no significant effects of iodine supplementation on neonatal and maternal thyroid function and birth outcomes, there were modest effects on neurocognitive development of children as assessed by executive function of children at 2 years. Thus, additional follow-up of these children for neurocognitive testing at a later age when development and cognitive testing is more reliable would provide valuable add on information; 2) The iodized salt program in Bangalore, India was providing adequate iodine to women throughout pregnancy, at the expense of higher iodine intake in their children, suggesting that the current WHO/UNICEF/ICCIDD cut-off for median UIC in children indicating more-than-adequate intake may need to be reconsidered; 3) Despite iodine sufficiency, many pregnant women had thyroid insufficiency predicted by low hemoglobin and higher BMI. The prevalence of overt hypothyroidism was >5-fold higher than reported in other iodine-sufficient populations of pregnant women, thus, screening of maternal thyroid function should be considered in antenatal care at hospitals in Bangalore, India; 4) Although iodine supplementation did not affect maternal depression, we highlighted the need for systemic screening for prenatal depression during antenatal visits as it is an independent risk factor for later development of clinical depression

Unravelling mechanisms of dietary flavonoid-mediated health effects: effects on lipid metabolism and genotoxicity
Hoek-van den Hil, E.F. - \ 2015
Wageningen University. Promotor(en): Ivonne Rietjens; Jaap Keijer, co-promotor(en): Peter Hollman. - Wageningen : Wageningen University - ISBN 9789462573031 - 157
flavanoïden - flavonoïden - vetzuren - quercetine - flavonolen - lichaamsgewicht - lipidenmetabolisme - hart- en vaatziekten - lever - vetweefsel - gezondheid - genotoxiciteit - voeding - muizen - flavanoids - flavonoids - fatty acids - quercetin - flavonols - body weight - lipid metabolism - cardiovascular diseases - liver - adipose tissue - health - genotoxicity - nutrition - mice

Summary

Consumption of foods containing flavonoids is associated with a reduced risk of cardiovascular diseases (CVD), possibly by lipid-lowering effects. On the other hand, for one of these flavonoids, quercetin, also genotoxicity was shown especially in in vitro bioassays. Therefore, the first aim of this thesis was to identify mechanisms underlying potential beneficial health effects of flavonoids. The focus was on hepatic lipid metabolism and circulating lipids and a molecular and physiological approach was used. Secondly, we aimed to study the potential in vivo genotoxic effects of quercetin by transcriptome analyses in liver and small intestine, since these represent the tissues of first contact exposed to relatively high levels upon oral intake of flavonoids.

Circulating lipids are important CVD-related risk markers, which are in general determined with commercially available enzyme-based assays. However, the usual enzyme in these assays, peroxidase, has previously been reported to be inhibited by flavonoids. Therefore, we have studied in chapter 2 whether these assays can adequately be used in flavonoid research. We observed that various flavonoid aglycones interfere with peroxidase used in triglycerides (TG) and free fatty acids (FFA) enzymatic assays, reporting incorrect lower TG and FFA levels than actually present. Furthermore, addition of metabolites such as isorhamnetin or quercetin-3-O-glucuronide, the major metabolite of quercetin in human and rat plasma, to murine serum also resulted in a significant reduction of the detected TG levels, while a trend was seen towards reduced FFA levels. It can be concluded that when applying these biochemical assays, vigilance is needed and alternative analytical methods assessing FFA or TG levels should preferably be applied for studying the biological effects of flavonoids on TG and FFA levels.

In chapter 3 mechanistic and physiological effects of quercetin on hepatic lipid metabolism were studied. C57BL/6JOlaHsd male adult mice received a mild high-fat (30 en%) diet without or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Gas chromatography and 1H-NMR were used to quantitatively measure serum lipid profiles. Whole genome microarray analysis of liver tissue was used to identify potential mechanisms underlying altered circulating lipid levels by quercetin supplementation. Body weight, energy intake and hepatic lipid accumulation did not differ significantly between the quercetin and the control group. In serum of quercetin-fed mice, TG levels were decreased by 14% (p<0.001) and total poly unsaturated fatty acids (PUFA) levels were increased by 13% (p<0.01). Levels of palmitic acid, oleic acid, and linoleic acid were all decreased by 9-15% (p<0.05) in quercetin-fed mice. Both palmitic acid and oleic acid can be oxidized by omega-oxidation. Gene expression profiling showed indeed that quercetin increased hepatic lipid metabolism, especially omega-oxidation. At the gene level, this was reflected by the up-regulation of cytochrome P450 (Cyp) 4a10, Cyp4a14, Cyp4a31 and Acyl-CoA thioesterase 3 (Acot3). Two relevant regulators, cytochrome P450 oxidoreductase (Por, rate limiting for cytochrome P450 activities) and the transcription factor constitutive androstane receptor (Car; official symbol Nr1i3) were also up- regulated in the quercetin-fed mice. We concluded that quercetin intake increased hepatic lipid omega-oxidation and lowered corresponding circulating lipid levels, which may contribute to potential beneficial effects of quercetin on CVD.

Subsequently, in chapter 4 effects of quercetin supplementation were studied in mice given a high-fat (40 en%) background diet. The set-up of the experiment was the same as in chapter 3, with the exception of the background diet that was used, which was different in fat content and composition. This high-fat diet-induced body weight gain, and serum and hepatic lipid accumulation, which are all known risk factors for CVD. The aim of this study was to investigate the effects and underlying molecular mechanisms of the effects of the flavonoid quercetin on hepatic lipid metabolism in mice given this high-fat diet background. C57BL/6JOlaHsd male adult mice received the high-fat diet without or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Body weight gain was 29% lower in quercetin fed mice versus control mice (p<0.01), while the energy intake was not significantly different. Quercetin supplementation lowered high-fat diet-induced hepatic lipid accumulation to 29% of the amount present in the control mice (p<0.01). 1H-NMR serum lipid profiling revealed that the supplementation also significantly lowered high-fat diet-induced increases in serum lipid levels. Global gene expression profiling of liver showed that cytochrome P450 2b (Cyp2b) genes, key target genes of the transcription factor Car, were down-regulated. However, the induction of omega-oxidation observed by quercetin supplementation to a mild high-fat (30en%) diet (chapter 3), was not observed this time with the high-fat (40en%) diet. Cumulatively, quercetin decreased high-fat diet-induced body weight gain, hepatic lipid accumulation and serum lipid levels. This was accompanied by regulation of cytochrome P450 2b genes in liver, which are considered to be under transcriptional control of CAR. The quercetin effects are likely dependent on the fat content and composition of the diet.

In chapter 5 we investigated whether flavonoids from other flavonoid subclasses can exert the same effects as we observed for quercetin. Effects of quercetin, hesperetin, epicatechin, apigenin and anthocyanins, in C57BL/6JOlaHsd male adult mice fed a high-fat diet for 12 weeks were compared, relative to a normal-fat diet. High-fat diet-induced body weight gain was significantly lowered by all flavonoids (17-29%), but most by quercetin. Quercetin significantly lowered high-fat diet-induced hepatic lipid accumulation (by 71%). High-fat diet-induced increases of mesenteric adipose tissue weight and serum leptin levels were significantly lowered by quercetin, hesperetin, and anthocyanins. Adipocyte cell size and adipose tissue inflammation were not affected.

The effects on body weight and adiposity could not be explained by individual significant differences in energy intake, energy expenditure, nor by differences in activity. Lipid metabolism was not changed as measured by indirect calorimetry or expression of known lipid metabolic genes in liver and white adipose tissue. Hepatic expression of Cyp2b9 was strongly down-regulated by all flavonoids. Overall, all five flavonoids lowered parameters of high-fat diet-induced adiposity, with quercetin being most effective.

Next to the beneficial health effects of flavonoids, the safety of flavonoids is under discussion, mainly because of potential genotoxic effects found for quercetin in vitro. Therefore, in chapter 6 the in vivo genotoxicity of this flavonoid was studied by transcriptome analyses in two tissues, small intestine and liver, where the highest exposure to quercetin is expected. This is especially of interest in view of high intake by widely available food supplements. Quercetin (0.33%) supplemented to a high-fat diet was administered to C57BL/6JOlaHsd male adult mice during 12 weeks. Serum alanine aminotransferase and aspartate aminotransferase levels revealed no indications for hepatotoxicity. General microarray pathway analysis of liver and small intestinal tissue samples showed no regulation of genotoxicity related pathways. In addition, analysis of DNA damage pathways in these tissues did also not point at genotoxicity. Furthermore, comparison with a published classifier set of transcripts for identifying genotoxic compounds did not reveal any similarities in the regulation of these classifier set by quercetin. Available microarray datasets of known genotoxic liver carcinogens, 2-acetylaminofluorene and aflatoxin B1 in mice were taken along as positive controls for comparison, and indeed showed genotoxic properties (regulation of genotoxic related genes) in the analyses. This transcriptomic analysis showed that supplementation with quercetin at ~350 mg/kg bw/day for 12 weeks did not induce genotoxicity in liver and small intestine.

In conclusion, we have shown in vivo efficacy of flavonoids reflected by effects on metabolic health parameters, including hepatic lipid metabolism. These effects on hepatic lipid metabolism seemed to be related or influenced by the transcription factor CAR. The dietary contexts appeared to modify the health effects. The five studied flavonoids in general showed the same effects, with quercetin being the most effective. No genotoxicity of quercetin was found by transcriptome analyses in liver and small intestine. Overall, we have obtained indications for beneficial health effects of flavonoids in mice, which makes it interesting to study if these effects can be extrapolated to humans to further explore their potential as functional compounds of dietary flavonoid intake.

Unravelling the genetics of iron status in African populations : candidate gene association studies
Gichohi-Wainaina, W.N. - \ 2015
Wageningen University. Promotor(en): Michael Zimmermann; Edith Feskens, co-promotor(en): Alida Melse-Boonstra; G.W. Towers. - Wageningen : Wageningen University - ISBN 9789462572102 - 198
ijzergebrekanemie - voeding - genetische factoren - eiwitten - volksgezondheid - voeding en gezondheid - populaties - afrika - iron deficiency anaemia - nutrition - genetic factors - proteins - public health - nutrition and health - populations - africa

Abstract

Background: Investigating the manner in which genetic and environmental factors interact to increase susceptibility to iron deficiency, has the potential to impact on strategies to overcome iron deficiency as well as the development of biomarkers to monitor iron status in populations. Single nucleotide polymorphisms or genetic variants that may affect the composition and hence the functionality of proteins involved in iron metabolism have been the subject of recent genetic association studies. However, these investigations have not yet been carried out in African populations that differ genetically from populations of European ancestry and which bear the highest burden of iron deficiency. The overall aim of this thesis was to investigate the genetics of iron status in African populations using a candidate gene approach.

Methods: In order to evaluate the association between identified TMPRSS6 gene variants and iron status we conducted a systematic review with meta-analyses. We primarily searched the literature using the HuGE Navigator, Pubmed and Scopus databases for primarily genome wide association studies. Fixed effects meta-analysis was used to obtain summary estimates. Associations between reported variants and iron status as well as gene-gene and variant interactions that influence iron status were investigated in a female black South African cohort (n=686; range 32–86 years) which were part of the Prospective Urban and Rural Epidemiology (PURE) study. Concentrations of haemoglobin, serum ferritin, serum transferrin receptor and body iron stores were determined. Thirty SNPs were genotyped and passed all quality criteria. To investigate whether previously identified associations in populations of European ancestry are replicated in populations of African ancestry, we conducted candidate gene association studies. Twenty iron status-associated variants in 628 Kenyans, 609 Tanzanians, 608 South Africans and 228 African Americans were genotyped and associations investigated using haemoglobin and serum ferritin as outcome measures. Finally, we assessed the effect of TNF-α allele variants (TNF‒1031, TNF‒308) on malaria rates, the severity of malaria as indicated by haemoglobin concentrations at the time of presentation with febrile episodes and the association between Plasmodium infection and haemoglobin concentration in symptomless parasite carriers. We used data from a placebo-controlled trial which consisted of 612 Tanzanian children aged 6–60 months. Cox regression models were used in the primary analysis to account for multiple episodes per child.

Results: In our systematic review we included eleven studies on Caucasian populations, four on Asian populations and one study on an African-American population. Differences in minor allele frequencies (MAF) of 8 TMPRSS6 SNPs (rs855791, rs4820268, rs2111833, rs1421312, rs228921, rs228918, rs228919 and rs575620) across ethnic groups were observed; with the MAF of rs855791 being significantly higher in Asian populations than in Caucasians (0.55 vs 0.42). In the meta-analysis, the A allele of rs855791 was associated with lower haemoglobin and ferritin concentrations in all populations. This allele was also associated with increased serum transferrin receptor and transferrin concentrations. We observed similar associations for the G allele in rs4820268. In general, minor allele frequencies (MAF) from females in the PURE population were lower compared to those of males and females of European ancestry populations in the 1000 Genomes Project. In the TF gene, the SNP rs1799852 was associated with decreased serum ferritin (p=0.01) and body iron concentrations (p=0.03) and increased serum transferrin receptor (sTfR) concentrations (P=0.004), while rs3811647 was associated with transferrin receptor and body iron (both P=0.03) in a U-shaped manner. The chromosome 6 SNP allele combination (AAA) consisting of rs1799964 and rs1800629 both in TNF α and rs2071592 in NFKBIL1 was associated with higher odds for low serum ferritin concentrations (serum ferritin<15µg/L; OR:1.86 (95%-CI, 1.23-2.79)). The chromosome 22 SNP allele combination (GG) consisting of rs228918 and rs228921 in the TMPRSS6 gene was associated with lower odds for increased sTfR concentrations (sTfR>8.3mg/L; OR:0.79 (95%-CI,0.63-0.98). We successfully replicated reported significant associations with lowered haemoglobin concentrations for two loci in TMPRSS6 namely rs2413450 and rs4820268 and with increased haemoglobin concentrations for one locus in TF (rs3811658) when analysing the four populations of African ancestry. When ferritin was considered as an outcome measure, we replicated associations with increased ferritin concentrations in two loci namely, rs228918 in TMPRSS6 and rs1525892 in TF. No other significant associations were determined. Malaria rates were higher in Tanzanian children with the TNF‒1031CC genotype (rs1799964) compared to the AA genotype (crude hazard ratio (HR), 95%CI: 1.41 [1.01‒1.97], adjusted HR 1.31 [0.97‒1.76]y) but were lower in those with the TNF‒308AA genotype (rs1800629) (adjusted HR 0.13 [0.02‒0.63]) compared to those harbouring the wild type homozygous genotype.

Conclusions: This thesis demonstrates previously observed associations between TMPRSS6 gene variants and haemoglobin concentrations in European ancestry populations are replicated in African populations. Replication of results in other loci previously associated with iron status in European ancestry populations was not achieved. Additionally, minor allele frequencies of single nucleotide polymorphisms associated with iron status are generally higher in European ancestry cohorts compared to those of African ancestry populations. The lack of association of reported variants may indicate that novel loci are responsible for the heritability of iron status in African populations. We have additionally observed that TNF α variants increase malaria severity. Malaria is a major cause of iron deficiency in malaria endemic areas. Our finding emphasizes that to alleviate iron deficiency in malaria endemic areas prevention and treatment of malaria is necessary. This thesis highlights the need to conduct genetic association studies in African populations where iron deficiency is of utmost public health significance. In addition, investigations into the genetics of iron status are bound to contribute towards the development of biomarkers that are useful in the determination of iron status in areas of high inflammation burden.

We are what we eat: An economic tool for tracing the origins of nutrients with entry points for action
Rutten, M.M. ; Tabeau, A.A. ; Godeschalk, F.E. - \ 2014
The Hague : FOODSECURE project office LEI Wageningen UR (University & Research centre) (FOODSECURE technical paper no. 28) - 65
voedselzekerheid - voedselvoorziening - ketenmanagement - economische analyse - scenario-analyse - voedingsstoffen - voeding - gezondheid - food security - food supply - supply chain management - economic analysis - scenario analysis - nutrients - nutrition - health
We develop a methodology for incorporating nutrition impacts in economy-wide analyses, providing entry points for where, when and how to act. It accounts for three channels of consumption, directly via primary commodities and indirectly via processed foods and food-related services, and produces indicators showing content by nutrient (currently calories, proteins, fats and carbohydrates), channel, source region and sector. The paper applies the framework in a CGE model (MAGNET) and uses FAO data to project nutritional outcomes resulting from the global food system over time. The analysis confirms that developing regions catch up with developed regions, with the USA at the high-end of nutrient consumption, whilst Southern Africa lags behind. In the USA the processed food channel dominates, whereas in Southern Africa the direct channel dominates. In the USA, and similar regions, fat taxes (thin subsidies) on unhealthy (healthy) processed foods, technologies reducing bad ingredients (e.g. trans fats, salt), improved food labelling, information and marketing campaigns, and/or targeted cash transfers may be worthwhile to investigate. In Southern Africa, and regions alike, technological advances increasing nutrient availability via primary agriculture and/or cash transfers enabling access may be more pertinent. The relative fixedness of sectoral origins shows that consumption habits change slowly and are visible only in the long term. For certain regions, including Southern Africa and USA, nutrient import dependency increases with substantial variations in regional sourcing. This implies that concerted action across the globe is crucial to reach diet, nutrition and health goals, and should include upcoming Asian economies, Africa (excl. Southern Africa) and the Middle East. Heterogeneity of results necessitates future ex-ante quantitative policy analyses on a more detailed and context-specific basis.
Toekomst met algen : waarom algen de mensheid kunnen redden
Bode, M. ; Leyenaar, A.J. ; Verbeek, I. ; Wal, L. van der - \ 2014
Wageningen : Wageningen UR - ISBN 9789462571945 - 31 p.
algen - biodiesel - voer - voeding - toekomst - bio-energie - algae - feeds - nutrition - future - bioenergy
Mucosal immunity : barriers, bugs, and balance
Neerven, R.J.J. van - \ 2014
Wageningen : Wageningen University, Wageningen UR - ISBN 9789462571952 - 24
immuniteit - immuniteitsreactie - immuunsysteem - immunologie - infectieziekten - ontsteking - orale vaccinatie - voeding - immunity - immune response - immune system - immunology - infectious diseases - inflammation - oral vaccination - nutrition
Towards healthy diets for parents: effectiveness of a counselling intervention
Hooft Van Huysduynen, E.J.C. - \ 2014
Wageningen University. Promotor(en): Cees van Woerkum, co-promotor(en): Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789462571532 - 114
ouders - gezondheid - voeding en gezondheid - voeding - dieetadvisering - dieet - counseling - voedingsgedrag - parents - health - nutrition and health - nutrition - diet counseling - diet - counselling - feeding behaviour

Towards Healthy Diets for parents: efectiveness of a counselling intervention

Eveline J.C. Hooft van Huysduynen

Abstract

Introduction and Objective: As parents’ modelling of dietary behaviour is one of the factors influencing children’s diets, improving parents’ diets is expected to result in improved dietary intake of their children. This thesis describes research that was conducted to develop and evaluate a counselling intervention to improve parental adherence to the Dutch dietary guidelines.

Methods: A counselling intervention was developed, which was underpinned with the theory of planned behaviour and the transtheoretical model. In 20 weeks, five face-to-face counselling sessions were provided by a registered dietician who used motivational interviewing to improve parental adherence to the Dutch dietary guidelines. In addition, parents received three individually tailored email messages. During the counselling, the dietary guidelines and additional eating behaviours, that were hypothesized to affect diet quality, were addressed. The intervention was evaluated in a randomised controlled trial with 92 parents receiving the counselling and 94 parents as controls. Effects on dietary intake, biomarkers, intermediate markers of health and children’s dietary intake were evaluated. With mediation analyses, it was investigated if changes in dietary intake were established via changes in behavioural determinants. Thereby, it was also examined if spot urine samples could be used to replace 24 h urine samples for evaluating changes in sodium and potassium intake.

Results: The intervention group increased their adherence to the dietary guidelines, as assessed with the Dutch Healthy Diet-index (ranging from 0 to 100 points), by 6.7 points more than the control group did. This improvement was achieved by small increases in the scores of seven out of ten index components. The most substantial changes were shown in fruit and fish intakes of which increases in fish intake were reflected in changes in fatty acid profiles derived from blood plasma. Also a small decrease in waist circumference was observed. Based on parental reports, the children in the intervention group increased their intakes of fruit, vegetables and fish more than the children in the control group. Improvements in parental fruit intake were mediated by changes in the behavioural determinants attitude and habit strength. Decreases in snack intake were mediated by changes in self-identity as a healthy eater. Although the results of a study in young Caucasian women showed that spot urine can be used to rank individuals for their ratios of sodium to potassium, no intervention effects on these ratios were observed.

Conclusion: This thesis provides empirical knowledge on potential effective elements for counselling interventions aiming at improving the dietary pattern as a whole of parents and provides knowledge on methods to evaluate changes in dietary intake.

Hypertension in Vietnam: prevalence, risk groups and effects of salt substitution
Do, H.T.P. - \ 2014
Wageningen University. Promotor(en): Edith Feskens; Frans Kok, co-promotor(en): Marianne Geleijnse. - Wageningen : Wageningen University - ISBN 9789462571372 - 159
hypertensie - risicogroepen - risico - gezondheid - zout - vervangmiddelen - voeding - levensstijl - vietnam - hypertension - risk groups - risk - health - salt - substitutes - nutrition - lifestyle - vietnam

ABSTRACT

Background: Over the past decades, the morbidity and mortality patterns have changed rapidly in Vietnam, with a reduction in infectious diseases in parallel with a rapid increase in non-communicable diseases (NCDs), leading to the so-called double burden. It was estimated that in 2008 NCDs accounted for 75% of all deaths in Vietnam, and cardiovascular diseases were the leading cause accounting for 40% of total mortality. Hypertension is one of the major risk factors for cardiovascular disease, but information on the nationwide prevalence and main determinants is lacking. There is an urgent need for appropriate population-based interventions for hypertension control and prevention in Vietnam.

Methods and Results: Data of 17,213 adults aged 25-64 years from the nationally representative 2005 National Adult Obesity Survey were used to study the prevalence of hypertension and prehypertension and their determinants. The overall prevalence of hypertension was 20.7% and the prevalence of prehypertension was 41.8%. Hypertension and prehypertension were more prevalent in men than in women (25.2% vs. 15.9%). Determinants of raised blood pressure including advancing age, overweight, alcohol use (among men), and living in rural areas (among women) were independently associated with a higher prevalence of hypertension, whereas higher levels of physical activity and education were inversely associated. Age, body mass index (BMI), and living in rural areas were independently associated with an increased prevalence of prehypertension. Among the hypertensives, only 25.9% were aware of having hypertension and 12.2% were treated. Among the treated hypertensives, 32.4% had their blood pressure controlled.

Overweight and obesity, important risk factors for hypertension, were investigated using data of 14,452 Vietnamese adults aged 25-64 years from the nationally representative 2000 National Nutrition Survey and data of 17,213 adults aged 25-64 years from the nationally representative 2005 National Adult Obesity Survey. The results showed that the distribution of BMI across the population and in population subgroups indicated a shift towards higher levels in 2005 as compared to 2000. The nationwide prevalences of overweight (BMI ≥ 25 kg/m2) and obesity (BMI ≥ 30 kg/m2) were 6.6% and 0.4% respectively in 2005, almost twice the rates of 2000 (3.5% and 0.2%). Using the Asian BMI cut-off of 23 kg/m2 the overweight prevalence was 16.3% in 2005 and 11.7% in 2000. Women were more likely to be both underweight and overweight than men in both 2000 and 2005. Urban residents were more likely to be overweight and less likely to be underweight as compared to rural residents in both years. The shifts from underweight to overweight were more pronounced in those with higher food expenditure levels.

A survey on sodium intake among a rural community near Hanoi (n=121) showed that mean 24-hour sodium excretion was 188.6 ± 57.5 mmol (4.3g), which corresponds to an intake of salt (sodium chloride) of 10.8 ± 3.3 g/day. Men had a higher mean sodium excretion (196.8 ± 56.9 mmol/day or 4.5g/day) than women (181.1 ± 57.4 mmol/day or 4.2g/day); 97.5% of the men and women had a salt intake higher than the World Health Organization’s recommendation of < 5g/day. Subjects with complete urine collection had a salt excretion of 11.7 g/day. Sodium in condiments added during cooking or eating at the table accounted for 81% of sodium intake. Processed foods contributed 11.6% and natural foods 7.4%. Regarding the condiments, the largest source was the mixed seasoning (35.1% of total); 31.6% of total dietary sodium was provided by fish sauce, 7.4% by monosodium glutamate and 6.1% by table salt.

Sodium-reduced and potassium-enriched salt and ‘bot canh’, a traditional seasoning, were experimentally produced and underwent organoleptic testing, which showed high acceptance. An 8-week randomized double-blind trial was carried out in 173 men and women between 45 and 64 years of age with untreated (pre)hypertension in a rural Vietnamese community. The intervention group that received sodium-reduced and potassium-enriched condiments (salt and bot canh) experienced a median 24-hour sodium excretion decrease of 28.5 mmol/d (1.6 g/d salt) compared to the control group that received regular condiments for home food preparation and dining. The mean change in BP in the intervention compared to the control group was -2.6 mmHg (95% CI: -4.6 to -0.5, p = 0.013) for systolic BP and -1.6 mmHg (95% CI: -3.0 to -0.2, p= 0.024) for diastolic BP. The prevalence of iodine deficiency was significantly reduced in both groups (from 66% to 41% in the intervention group and from 72% to 36% in the controls).

Conclusion: Hypertension and prehypertension are prevalent in Vietnam, but awareness, treatment, and control are low. Lifestyle modifications, including the prevention of overweight, and the promotion of physical activity, particularly in urban areas, and the reduction of high alcohol consumption in men, may help to prevent hypertension in Vietnam. Between 2000 and 2005, BMI in the population shifted towards higher levels, especially in those with higher food expenditure levels, but under nutrition was also still prevalent in 2005. Most dietary sodium (81%) comes from adding salty condiments during food preparation or at the table. Therefore, limiting condiments added during cooking and at the table should be given priority. Alternatively, regular condiments may be replaced with sodium-reduced and potassium-enriched salt and ‘bot canh’ to lower BP in (pre)hypertensive Vietnamese adults. Salt iodization should be reconsidered to ensure adequate iodine intake of the population.


TABLE OF CONTENTS

Chapter 1

General introduction

1 - 24

Chapter 2

National prevalence and associated risk factors of hypertension and prehypertension among Vietnamese adults.

American Journal of Hypertension, Epub ahead of print 2014/05/28

25 - 44

Chapter 3

Nationwide shifts in the double burden of overweight and underweight in Vietnamese adults in 2000 and 2005: two national nutrition surveys.

BMC Public Health 2011, 11:62

45 - 66

Chapter 4

Sodium intake and its dietary sources in Vietnamese rural adults

Submitted

67 - 80

Chapter 5

Sodium-reduced and potassium-enriched condiments reduce sodium intake and blood pressure in Vietnamese adults: a randomized controlled trial.

Submitted

81 - 100

Chapter 6

General discussion

101 - 120

Summary

Summary in Dutch

Summary in Vietnamese

Acknowledgment

About the author


Nutrition and cognition in older adults : studies on the role of glucose, sucrose, protein, vitamin B12 and folic acid
Zwaluw, N.L. van der - \ 2014
Wageningen University. Promotor(en): Lisette de Groot, co-promotor(en): Ondine van de Rest; Rosalie Dhonukshe-Rutten. - Wageningen : Wageningen University - ISBN 9789462571075 - 184
ouderenvoeding - voeding - ouderen - kenvermogen - glucose - sucrose - eiwittoevoegingen - vitamine b12 - dementie - elderly nutrition - nutrition - elderly - cognition - glucose - sucrose - protein supplements - vitamin b12 - dementia

The age-related cognitive decline and the increase in dementia patients are large problems in societies with growing ageing populations. No cure is present for dementia, while the available medication only focuses on alleviating symptoms. It is therefore of major importance to find risk factors that can modify the development of cognitive decline and dementia. Pre-clinical and observational studies suggest a role for nutrients. Evidence derived from randomized controlled trials (RCTs) is, however, limited and equivocal with most studies showing no effect and only a few studies showing a beneficial effect of a nutritional intervention. In the current thesis, we investigated the acute and longer-term effects of different nutrients, i.e. glucose and sucrose, protein, resistance-type exercise training with or without protein, and vitamin B12 and folic acid in order to optimize and preserve cognitive functions in non-demented elderly people.

A comprehensive literature review was performed on the acute effects of glucose and sucrose on cognitive performance (Chapter 2). Glucose is the most important fuel for the brain, and as such, manipulation of the supply of glucose may affect cognitive functions. The main conclusion of our review was that a glucose load may have a short-term beneficial effect on episodic memory. Enhancing effects on other cognitive domains were less clear, partly due to the small number of studies examining these effects. Limited research was also done on the possible effects of sucrose on cognitive functions. Therefore, we investigated the acute effects of 50 g of glucose and 100 g of sucrose on a broad spectrum of cognitive functions reflecting performance on episodic memory, working memory, attention and information processing speed, and executive functions (Chapter 3). This was done by a cross-over study in 43 elderly participants who had self-reported memory complaints. In contrast to the conclusion of our review, we did not observe an effect of glucose or sucrose on episodic memory, though we showed a beneficial effect of sucrose on attention and information processing speed.

Protein supplementation was the next nutritional intervention that was investigated. Several amino acids are precursors for neurotransmitters, and their supply may affect the synthesis and release of these neurotransmitters, and may consequently affect cognitive performance. A 24-week randomized placebo-controlled trial was carried out in 65 frail and pre-frail elderly people (Chapter 4). The protein supplementation included twice a day 15 grams of protein in the form of a drink. Reaction time improved more in the protein group compared to the placebo group, but the scores on the cognitive domains, i.e. episodic memory, attention and working memory, information processing speed, and executive functions, or the other single test scores, did not differ between treatment groups. In addition, we investigated the effects of 24 weeks resistance-type exercise training with and without protein supplementation in pre-frail and frail elderly people (Chapter 5). Exercise training without extra protein (n=62) improved performance on the domain attention and working memory. Exercise training together with protein supplementation (n=65) improved performance on information processing speed.

Last, the role of vitamin B12 and folate on cognitive health was investigated. Low levels of these nutrients can increase homocysteine levels, which is a suggested risk factor for cognitive decline. The effect of daily supplementation with 500 µg vitamin B12 and 400 µg folic acid was investigated in 2,919 participants for two years (Chapter 6). Global cognitive function and episodic memory were assessed in the total study population, whereas extensive neuropsychological testing was done in a subpopulation (n=856). B-vitamin supplementation did not improve cognitive domain scores. Only a small, though significant, effect was observed on global cognitive performance, measured by the Mini-Mental State Examination, but this was suggested to be due to chance. Brain MRI scans were made in a subgroup (n=218) after two years of intervention to obtain volumetric measures of grey and white matter, and total brain volume (Chapter 7). We investigated the cross-sectional associations between follow-up levels of folate, homocysteine and three vitamin B12 status biomarkers, e.g. methylmalonic acid, holotranscobalamin and serum vitamin B12, and brain volumes. Fully adjusted regression models showed a borderline significant association between plasma homocysteine and total brain volume, with a stronger association in the group that received B-vitamin supplementation. Serum B12 and holotranscobalamin were not associated with brain volumes, whereas high methylmalonic acid levels were associated with lower brain volumes in the group that received B-vitamins. In contrast, higher folate levels were associated with lower total brain volumes. In addition, when comparing the group that received two years of B-vitamin supplementation and those who did not, we observed lower brain volumes in the B-vitamin group, which might be a result of a difference in age between the two groups.

To conclude, the nutritional intervention studies showed little evidence for a beneficial effect on cognitive performance in relatively healthy older adults. Given the large problem of dementia, research on modifiable risk factors, including nutrition, should continue, with well thought out research methods, including large and long-term observational and intervention studies with high-sensitive study populations and early biomarkers (e.g. imaging techniques) for cognitive decline in combination with neuropsychological tests. In this way, nutrition can be added to the list of lifestyle factors that can fight dementia.

Onderwijskundige Arjen Wals wil duurzaamheid tussen de oren krijgen: "biologie werkt beter van buiten naar binnen"
Maanen, G. van; Wals, A.E.J. - \ 2014
Bionieuws 24 (2014)11. - ISSN 0924-7734 - p. 11 - 11.
natuur- en milieueducatie - voeding - duurzaamheid (sustainability) - duurzame ontwikkeling - nature and environmental education - nutrition - sustainability - sustainable development
De kloof tussen duurzaam denken en duurzaam doen overbrug je door op scholen exacte vakken te integreren met natuur- en milieu-educatie en slimme ict-burgerwetenschap, meent de Wageningse onderwijskundige Arjen Wals.
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