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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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Bovine lactoferrin enhances TLR7-mediated responses in plasmacytoid dendritic cells in elderly women : Results from a nutritional intervention study with bovine lactoferrin, GOS and Vitamin D
Splunter, Marloes van; Perdijk, Olaf ; Fick-Brinkhof, Henriëtte ; Feitsma, Anouk L. ; Floris-Vollenbroek, Esther G. ; Meijer, Ben ; Brugman, Sylvia ; Savelkoul, Huub F.J. ; Hoffen, Els van; Neerven, R.J.J. van - \ 2018
Frontiers in Immunology 9 (2018). - ISSN 1664-3224
aging - bovine lactoferrin - GOS - inflammation - mDCs - pDCs - TLR stimulation - Vitamin D

During aging the immune system is dysregulated. Especially plasmacytoid dendritic cells (pDCs) and myeloid DCs (mDCs) have reduced Toll like receptor (TLR)-mediated responses resulting in increased susceptibility to infections. Consumption of bovine lactoferrin (bLF) has been shown to reduce infections with viruses. Galacto-oligosacharides (GOS) and Vitamin D are associated with reduced pro-inflammatory cytokine levels in serum, and increased TLR7/8 responses, respectively. A double-blind placebo-controlled nutritional intervention study in elderly women was performed, to investigate the potential of bLF, GOS, and Vitamin D to restore TLR responsiveness of pDCs and mDCs and to reduce inflammatory markers in serum. The nutritional intervention group (n = 15) received bLF for 3 weeks, followed by 3 weeks of bLF + GOS, and subsequently 3 weeks of bLF + GOS + Vitamin D. The placebo group (n = 15) received maltodextrin for 9 weeks. Every 3 weeks, blood was collected and TLR responses of pDCs and mDCs, and inflammation-related markers in serum were measured. After 3 weeks of bLF supplementation, increased TLR7/8 and TLR1/2 responses were observed in pDCs of the nutritional intervention group compared to the placebo group. When the effects of the entire nutritional intervention were investigated, increased TLR1/2 mediated responses in mDCs were observed, and in serum sVCAM tended to decrease. Finally, based on the RAND-36 questionnaire physical function tended to improve in the intervention group. Since especially TLR7-mediated responses in pDCs were enhanced after bLF supplementation compared to placebo, this suggests that bLF may contribute to antiviral responses mediated by pDC in elderly women.

Dietary patterns for healthier cognitive ageing
Berendsen, Agnes A.M. - \ 2017
Wageningen University. Promotor(en): Lisette de Groot; Edith Feskens, co-promotor(en): Ondine van de Rest. - Wageningen : Wageningen University - ISBN 9789463436014 - 190
meal patterns - feeding habits - aging - cognition - health - food supplements - dementia - nutritional intervention - elderly - elderly nutrition - nutrition and health - maaltijdpatronen - voedingsgewoonten - verouderen - kenvermogen - gezondheid - voedselsupplementen - dementie - maatregel op voedingsgebied - ouderen - ouderenvoeding - voeding en gezondheid

With ageing of our population and the accompanying increase in the number of people living with dementia, it is important to find modifiable risk factors to postpone the onset of cognitive decline. Diet has been proposed such a modifiable risk factor. To date, numerous studies have been conducted demonstrating a possible role of specific nutrients and foods in cognitive functioning. However, as people do not consume single nutrients, the research field has shifted towards studying dietary patterns in which synergistic effects of single nutrients and/or foods can be studied. The main aim of this thesis was to study the association of healthful dietary patterns with cognitive functioning. In addition, nutrient intake inadequacies were assessed and the potential to change dietary intake in older adults aged 65 years and older was studied.

Chapter 2 describes nutrient intake of 245 Dutch adults aged 65-80 years. We identified the contribution of nutrient dense foods, fortified foods and dietary supplements to the total intake of micronutrients. Nutrient density of foods was evaluated using the Nutrient Rich Food score 9.3. Nutrient intake inadequacies were observed for vitamin D, vitamin B6 and selenium. Conventional foods were the main source of vitamin D, vitamin B6 and selenium intake. Foods with the highest nutrient density contributed most to total vitamin B6 intake. In order to optimize nutrient intakes of elderly, combinations of natural food sources, fortified foods and dietary supplements should be considered.

Chapter 3 provides a systematic review of the literature on human studies up to May 2014 that examined the role of dietary patterns in relation to cognitive decline or dementia. The results demonstrate that better adherence to a Mediterranean diet was associated with less cognitive decline, dementia or Alzheimer’s Disease (AD) in four out of six cross-sectional studies, six out of 12 longitudinal studies, one trial and three meta-analyses. Other healthy dietary patterns, among which the Healthy Diet Indicator, have shown to be associated with reduced cognitive decline and/or a reduced risk of dementia in all six cross-sectional studies and six out of eight longitudinal studies. The conclusion of this literature review was that more conclusive evidence is needed to come to more targeted and detailed dietary guidelines to prevent or postpone cognitive decline.

In chapter 4 the association between the Healthy Diet Indicator (HDI) and cognitive functioning in older adults from three different cohort studies was investigated. The cohorts included in total 21,837 subjects from Europe (SENECA and the Rotterdam Study [RS]) and the Unites States (Nurses’ Health Study [NHS]). Cognitive functioning was measured using the Mini-Mental State Examination (MMSE) in SENECA and RS, and the Telephone Interview for Cognitive Status (TICS) in NHS. In all three cohorts, the HDI was not significantly associated with cognitive decline, nor with cognitive function.

In chapter 5 the association of long-term adherence to the Dietary Approaches to Stop Hypertension (DASH) diet with cognitive function and decline in older American women was examined. A total of 16,144 women from the Nurses’ Health Study, aged ≥70 years, who underwent cognitive testing a total of 4 times by telephone from 1995-2001 (baseline), with multiple dietary assessments between 1984 and the first cognitive exam were studied. Greater adherence to long-term DASH score was significantly associated with better average global cognition, verbal memory and TICS score at older ages, but not with cognitive decline.

In chapter 6, the same cohort as in chapter 5 was studied to examine the association between long-term adherence to a recently developed Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet with cognitive function and decline. Higher MIND diet scores were associated with better verbal memory at older ages, but not with cognitive decline over 6 years in global cognition, verbal memory or TICS.

Chapter 7 provides an overview of the NU-AGE (NUtrients and AGEing) dietary intervention study. The NU-AGE study is a randomized one-year intervention in 1,250 apparently healthy, independently living European subjects aged 65 to 80 years. Subjects were randomised into either the intervention group or the control group. Participants in the intervention group received dietary advice aimed at meeting the dietary recommendations of the ageing population. At the start of this thesis, the NU-AGE study was the first dietary intervention investigating the effect of a whole diet and providing targeted dietary recommendations for optimal health and quality of life in apparently healthy European elderly.

In chapter 8, we evaluated if the NU-AGE intervention could be effective to shift the dietary intake of apparently healthy older adults aged 65-80 years living in Italy, the UK, the Netherlands, Poland, and France towards a more healthful diet. The NU-AGE index was created to assess adherence to the NU-AGE diet. At baseline and after one-year follow-up dietary intake was assessed by means of 7-day food records. In total, 1,296 participants were randomized and 1,145 participants completed the intervention (571 in intervention group, 570 in control group). After one-year follow-up, the intervention group improved mean intake of 13 out of 16 dietary recommendations of the NU-AGE diet (p<0.05) with a significant increase of the total NU-AGE index, compared to the control group (mean change in NU-AGE index 21.3±15.9, p<0.01). The NU-AGE dietary intervention, based on dietary recommendations for older adults, may be a feasible strategy to improve dietary intake in an ageing European population.

Chapter 9 shows the results of the NU-AGE parallel randomized dietary intervention study on cognitive functioning in the Dutch NU-AGE subpopulation, including 252 older adults aged 65-80 years (123 intervention, 129 control). The primary outcome was one-year change in global cognition and in four cognitive domains as measured through a comprehensive neuropsychological test battery. Comparing the intervention with the control group, there was no effect of the intervention on cognitive functioning.

In chapter 10 the main findings of this thesis were summarized and a reflection on methodological aspects was given. When grading the reported associations in previous studies and studies in this thesis, it was concluded that there is probable evidence for a role of the Mediterranean diet on cognitive functioning. For the DASH and MIND diet there is a possible link with cognitive functioning; for the HDI and the NU-AGE diet there is no sufficient evidence yet to conclude that there is a relation with cognitive functioning. Not only is there a need for well-designed intervention and prospective studies, we also call for communication strategies to the general public about the consumption of healthier diets to not only impact cardiovascular but also potentially impact brain health as many individuals will face progressive cognitive decline in the near future.

Vitamin D for older adults : Determinants of status, supplementation strategies and its role in muscle function
Vaes, Anouk M.M. - \ 2017
Wageningen University. Promotor(en): Lisette de Groot, co-promotor(en): M. Tieland. - Wageningen : Wageningen University - ISBN 9789463436144 - 164
vitamin d - deficiency - aging - vitamin supplements - dosage effects - musculoskeletal system - literature reviews - food enrichment - skeletal muscle - food supplements - randomized controlled trials - vitamine d - deficiëntie - verouderen - vitaminetoevoegingen - doseringseffecten - skeletspierstelsel - literatuuroverzichten - voedselverrijking - skeletspier - voedselsupplementen - gestuurd experiment met verloting

Vitamin D has been identified as an important factor in healthy aging and is receiving growing attention in clinical research. Vitamin D is a fat-soluble molecule, which is synthesized by hepatic and renal or extra-renal hydroxylation into the active hormone 1,25-dihydroxyvitamin D (1,25(OH)2D). The main function of this metabolite is to regulate calcium and phosphorus homeostasis and to support bone mineralization. In the circulation, the 25-hydroxyvitamin D metabolite (25(OH)D) is most stable and thus, considered the best marker of vitamin D status. A serum 25(OH)D concentration <30-50 nmol/L is considered deficient. Given the increased risk of deficiency and the potential beneficial effect of supplementation on musculoskeletal health, older adults present a specific target group for vitamin D interventions. However, the optimal serum 25(OH)D concentration is a matter of ongoing debate as randomized trials show conflicting results.

With the research presented in this thesis, we aimed to gain insight in the prevalence and main determinants of a low vitamin D status, to investigate strategies to prevent or reverse vitamin D deficiency, and to study the effect of vitamin D supplementation on muscle strength and physical performance in Dutch older adults.

In chapter 2, we examined the prevalence and the main determinants of a low vitamin D status in a large population of community-dwelling older adults (n=2857). Vitamin D deficiency was highly prevalent, with serum 25(OH)D concentrations <50 nmol/L in 45%, and <30 nmol/L in 14% of the population. When exploring the main determinants of serum 25(OH)D status, significant associations were observed with age, BMI, dietary intake, sun exposure behavior, and genetic polymorphisms encoding for enzymes in the vitamin D pathway. Combined, these factors explained 35% of the variation in serum 25(OH)D concentrations.

To explore potential strategies that prevent vitamin D deficiency, we investigated the contribution of dietary vitamin D intake and specific food groups to serum 25(OH)D concentration in chapter 3. Daily vitamin D intake from dietary sources showed a median (25-75th percentile) intake of 4.0 (3.0-5.4) µg/day (n=595) and only 12-20% of older adults reported to take vitamin D supplements. These findings are in sharp contrast with the current nutrient guidelines and show that the vast majority of older adults do not meet the reference intakes for vitamin D. Nevertheless, significant associations were observed between the highest tertile of dietary vitamin D intake and serum 25(OH)D concentration, suggesting that regular intake of foods rich in vitamin D can support the prevention of modest insufficiency.

For the majority of older adults, supplementation is required to ensure sufficient serum 25(OH)D concentrations throughout the year. Currently, supplementation with vitamin D3 is the most common strategy. However, alternative treatment regimens exist that require further investigation. In chapter 4, we report on a dose-response trial (n=59) that investigated the efficacy of calcifediol (5, 10 or 15 µg/d) as a supplementation strategy. Compared to vitamin D3, calcifediol is more hydrophilic, does not require hepatic hydroxylation, and binds with higher affinity to its binding proteins. In our study, we observed that calcifediol was safe and well tolerated in the supplemented doses over the entire study period of 6-months. We concluded that a dose of 10 µg/day resulted in sustained serum 25(OH)D concentrations between 75-100 nmol/L. Furthermore, calcifediol had a ~3 times higher potency when compared to vitamin D3, in increasing serum 25(OH)D concentrations. All in all, calcifediol may offer a valuable supplementation regimen to rapidly correct deficiency.

Vitamin D presents an important endocrine regulator in the musculoskeletal health of older adults. Besides its role in bone health, low serum 25(OH)D concentrations have been linked to impaired physical performance and increased risk of falling. The active metabolite 1,25-dihydroxyvitamin D is suggested to act upon a wide variety of cells throughout the body, including muscle cells. Although the exact mechanisms by which vitamin D acts on muscle are unclear, several indirect or direct regulatory pathways have been described, including effects of 1,25-dihyroxyvitamin D through intracellular calcium and phosphate homeostasis, or via activation of transcription factors when binding to the vitamin D receptor in muscle cells.

In chapter 5 we observed significant associations between low serum 25(OH)D concentrations, physical performance and frailty in community-dwelling older adults (n=494-756). However, randomized trials are needed to define the causality of the observed associations. A previous pilot study indicated plausible beneficial effects of calcifediol over vitamin D3 on performance and strength. As such, we aimed to further explore the potential role of calcifediol or vitamin D3 on muscle function in chapter 6. We performed a placebo-controlled trial in pre-frail and frail, vitamin D deficient older adults, supplementing either 10 µg/d calcifediol or 20 µg/d vitamin D3, compared to placebo over a 6-month period (n=78). Again, calcifediol induced a faster and higher increase in serum 25(OH)D status when compared to vitamin D3. However, we observed no effect of either supplementation regimen on lower extremity strength or physical performance. Current literature suggests positive effects on strength and balance when supplementing with vitamin D, however, results are inconsistent. Meta-analyses of randomized trials indicate that the beneficial effects of vitamin D supplementation might be more pronounced in vulnerable populations with more severe vitamin D deficiencies.

All in all, the high prevalence of vitamin D deficiency is alarming. Promoting adequate vitamin D status is important considering the beneficial effects on bone health. In the last decade, research has come a long way in exploring the role of vitamin D in muscle function. However, the evidence base remains uncertain and further research on the optimal vitamin D status for older adults is needed to guide clinical practice. Until then, focus should be placed on prevention and identification of deficiency.

Diet-induced phenotypic plasticity during aging
Rusli, Fenni - \ 2016
Wageningen University. Promotor(en): Michael Muller, co-promotor(en): Wilma Steegenga. - Wageningen : Wageningen University - ISBN 9789462578845 - 179
diet - liver diseases - energy restricted diets - fibroblasts - aging - fatty liver - dieet - leverziekten - energiearme diëten - fibroblasten - verouderen - vetlever

Increasing life expectancy in the past decades has led to the emergence of age-related chronic diseases and disabilities. A deeper understanding in the molecular events of the aging process is essential to provide evidence-based guidance how lifestyle interventions will be more efficient in delaying age-related disease phenotypes. Calorie restriction (CR) is by far the best nutritional strategy to achieve longevity in animal models. Although potentially also effective for humans, most people experience this rigorous diet as not feasible. To search for a practicable alternative we explored, using a C57BL/6J mice cohort, the effects of intermittent (INT) diet, a weekly alternating diet regimen between 40E% CR and ad libitum medium-fat feeding. We hypothesized that the weekly fluctuating energy availability provides beneficial challenges to the body.

In this thesis we focused on the effects induced by the INT diet on the liver, the central metabolic organ in the body. Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease that develops with age and is considered as the hepatic phenotype of the metabolic syndrome. NAFLD is a disease that develops slowly over the years; its prevalence has been shown to increase at old age (>60 years). In chapter 2 we investigated whether the INT dietary regimen was able to reverse the unfavourable effects of a medium-fat (25%E fat; MF) diet on the liver and its implication on NAFLD development. We showed that, at the age of 12 months, the INT diet prevented NAFLD development. INT-exposed animals retained healthy physiological features as displayed by continuous exposure to CR; maintenance of glucose tolerance, normal insulin levels and low plasma alanine and aspartate aminotransferases. Furthermore, they did not exhibit signs of hepatic steatosis and fibrosis, indicated by the reduced hepatic TG levels and morphological observations. The results presented in chapter 3 show that, at the age of 24 months, INT-fed mice displayed normal plasma ALT levels, no liver inflammation or fibrosis. These mice, however, display mild steatosis with IHTG levels significantly lower than the MF-exposed mice. To summarize, long-term exposure to a MF diet seriously impaired metabolic homeostasis and was a risk factor for NAFLD development. Applying every-other-week 40E% CR largely reversed the adverse health effects induced by the MF diet. Although the livers of the INT-exposed mice were still protected for the advanced stages of NAFLD, it is noteworthy that, in the long run, liver fat accumulation still occurred.

The second part of chapter 3 describes the obesity-counteracting effects of the INT diet. Part of the mice that had been exposed to the MF diet till 12 months of age was switched to the INT diet until the age of 24 months. The switch to the INT diet successfully improved glucose clearance, survival and liver health, but failed to improve IHTG levels. Within the diet switch experiment, we also investigated the plasticity of adaptive response to the switch by means of transcriptome analysis. Most of the genes differentially expressed between the INT- and MF-exposed mice (~95% of 2,667 genes) switched to the INT-expression profile. There was only a small subset of 148 genes which expression levels persistently remained similar to the MF diet-induced expression levels, instead of adapting to INT’s expression profile. Pathway analysis pointed out that this subset of 148 genes contains genes involved in lipid and xenobiotic metabolism, with PXR as the strongest upstream regulator. This suggests that MF-induced deregulated PXR activity persistently affects lipid and xenobiotic metabolism in the liver of the old diet switch mice. Therefore, we suggested that, despite the strong improvement of overall and liver-specific phenotypes, these persistently regulated genes might have potentially adverse effects on health.

The adaptive response to the diet switch at an old age was further investigated in chapter 4, but then in the reverse order: switching from a healthy to an unhealthy diet. Our results showed that, despite the long-term exposure to CR regimen, mice in the CR-MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR-improved survival was observed in the diet switch group. The liver transcriptomic profile of CR-MF group largely shifted to a profile similar to the MF-fed animals but leaving ~22% of the 1578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the life-long CR group. Therefore, although the diet switch was performed at an old age, the CR-MF-exposed mice were still able to rapidly gain weight to similar level as life-long MF mice with the same age, but without developing severe liver pathologies.

In chapter 5, the data from the different dietary interventions and age time points were combined to further explore the molecular mechanisms underlying the NAFLD development. Hereby, we focussed our analysis on the association with Fgf21, an emerging non-invasive biomarker for NAFLD. We demonstrated that plasma Fgf21 levels strongly reflected liver fat accumulation, confirming its potential as NAFLD marker. Transcriptomics analysis of the liver was performed and revealed that the link between plasma Fgf21 and IHTG levels was associated with differentially regulated PPARα and NRF2 targets during NAFLD. This suggested that the elevated Fgf21 levels in NAFLD was a measure to maintain homeostasis against the adverse effects of lipotoxicity, oxidative stress and endoplasmic reticulum stress in NAFLD. The PPARα challenge test, which was performed by administrating PPARa agonist Wy-14,643 to the mice, confirmed the dysregulation of PPARα signalling in NAFLD, including the hepatic expression of Fgf21.

To conclude, the results presented in this thesis adds to our understanding the effects of different diets have on genotype-phenotype relationships, which translate into different health states and are essential for identifying healthy aging strategies. We investigated the role of different dietary regimen on the phenotypes of genetically identical mice, particularly on an intermittent (INT) diet, which alternates weekly between the ad libitum medium-fat (MF) and calorie restriction (CR) diet. We found that the INT dietary regimen provided a remarkable protection against the severe health outcomes of the long-term medium-fat diet consumption, which may improve life quality by reducing the burden of chronic disease. Although it is too early to conclude that the INT dietary regimen (or modulation of the energy intake) is beneficial and safe to be applied in human population, this study is a proof-of-concept of intervening a chronic overnutrition status with a metabolic challenge of energy stress. Further investigation of this novel dietary regimen is needed to allow it to be safely applied in humans. By switching the diets at a defined time point during the study, we demonstrated that, even at middle and old age, the liver is still a highly flexible organ that rapidly adapts its transcriptional program to the different dietary challenges. We also demonstrated that the strong link between the diet-induced NAFLD and Fgf21 denoted a dysregulation of PPARa signalling pathway during the development of the liver disease.

Human nutrition : a crunchy bite
Kok, F.J. - \ 2015
Wageningen : Wageningen University - ISBN 9789462573703 - 28 p.
obesity - malnutrition - infant nutrition - nutrition and health - nutrition research - human nutrition research - vitamins - aging - pregnancy - abdominal fat - body fat - obesitas - slechte voeding - zuigelingenvoeding - voeding en gezondheid - voedingsonderzoek - voedingsonderzoek bij de mens - vitaminen - verouderen - zwangerschap - buikvet - lichaamsvet
Farewell address upon retiring as Professor of Nutrition and Health
at Wageningen University on 15 October 2015
Ecdysteroid hormones link the juvenile environment to alternative adult life histories in a seasonal insect
Oostra, V. ; Mateus, A.R.A. ; Burg, K.R.L. van den; Piessens, T. ; Eijk, M. van; Brakefield, P.M. ; Beldade, P. ; Zwaan, B.J. - \ 2014
development - endocrinology - evolution - life history - aging - phenotypic plasticity - physiology - seasonal adaptation - ecdysone
Four datasets from: Ecdysteroid hormones link the juvenile environment to alternative adult life histories in a seasonal insect; by Oostra, Vicencio; Mateus, Ana Rita A.; Van der Burg, Karin R.L.; Piessens,Thomas; Van Eijk, Marleen; Brakefield, Paul M.; Beldade, Patrícia; Zwaan, Bas; as published in American Naturalist 2014. This ZIP archive contains four csv data files: 1) experiment1.csv; 2) experiment2_dataset1.csv; 3) experiment2_dataset2.csv; 4) experiment2_dataset3.csv. See readme.txt for details.
Vitaal naar de eindstreep
Tieland, C.A.B. ; Rest, O. van de; Groot, C.P.G.M. de - \ 2013
WageningenWorld 2013 (2013)4. - ISSN 2210-7908 - p. 26 - 29.
voeding en gezondheid - ouderen - verouderen - vitaminetekorten - vetzuren - eiwit - gezondheidsbevordering - nutrition and health - elderly - aging - vitamin deficiencies - fatty acids - protein - health promotion
Hoe worden we gezond oud? Trainen en extra eiwitten werken, blijkt uit onderzoek van de afdeling Humane voeding. Over het effect van vitamines en omega-3 vetzuren is het laatste woord nog niet gezegd.
Anthropometrics and ageing : impact of weight status on health
Hollander, E.L. de - \ 2013
Wageningen University. Promotor(en): Lisette de Groot, co-promotor(en): W.J.E. Bemelmans. - S.l. : s.n. - ISBN 9789461736888 - 176
antropometrie - antropometrische dimensies - lichaamsgewicht - verouderen - ouderen - gezondheid - anthropometry - anthropometric dimensions - body weight - aging - elderly - health

Background: Weight status is one of the factors that influence healthy ageing. It is often assessed with anthropometric measures such as body mass index (BMI) and waist circumference (WC), which indicate underweight or excess fat. Both are associated with adverse health outcomes in adults. The first paper of this thesis investigates whether this association is consistent over calendar time, to check for possible influences of improved healthcare procedures over time. In old age, this association is unclear. Using several anthropometric measures, the subsequent five papers examine the impact of weight status and development of weight status on coronary heart disease (CHD), mortality, and quality of life (QoL) among the elderly and during ageing.

Methods: A meta-regression analysis of 31 international cohort studies (n=389,212) was used to estimate the multivariable adjusted relative risk (RR) of CHD for an increased BMI and whether the RR was different between calendar periods (i.e. studies that started before 1985 and studies that started after 1985) taking account of the age of the population. Associations of BMI and changes in eight anthropometric measures with all-cause and cause-specific mortality in old age were studied by means of multivariable Cox regression analyses using data from the Survey in Europe on Nutrition and the Elderly: a concerted action study including 70–77-year-olds (n=1,061–1,970). Moreover, the association of WC with all-cause and cause-specific mortality was studied by means of a meta-analysis of 29 international cohort studies including 65–74-year-olds (n=58,609). For an ageing population, we used the Doetinchem Cohort Study including 20–70-year-olds (n=3,408–4,135) and three to four repeated measures of weight and height over a period of 10 to 15 years. In this study population, we used a multivariable regression analysis to examine the association of changes in weight and long-term BMI patterns with QoL (measured by the SF-36 questionnaire).

Results: After simultaneous inclusion of calendar period and age of the population in the model, the meta-regression analysis showed no difference in the RR of CHD in the association with a high BMI between calendar periods. However, a 10-year increment in population age lowered the 1.28 [95%confidence interval (CI): 1.22–1.34] RR of CHD for a five-BMI-unit increment by 29% (95%CI: -55 to -5). Among the elderly, BMI was associated with all-cause mortality, cardiovascular disease (CVD) mortality, and mortality due to causes other than CVD, cancer, and respiratory diseases (p<0.05). A BMI below 24 kg/m2and above 30 kg/m2were the thresholds at which risks of cause-specific mortality were increased by 10%. WC was associated with all-cause, CVD, cancer, and respiratory disease mortality (p<0.05). At the levels for abdominal obesity (102 cm, men; 88 cm, women), the risk of all-cause and CVD mortality was not significantly increased, or only modestly. A risk of 2.0 (clinically relevant) for all-cause and CVD mortality was associated with a WC of 132 and 123 cm in men, and 116 and 105 cm in women, respectively. By using a combination of WC and BMI categories with the combination of a small WC (94 cm, men; 80 cm, women) and a healthy weight (20.0–24.9 kg/m2) as the reference, we observed the highest all-cause and CVD mortality risk of approximately 2.0 for underweight (<20.0 kg/m2; in combination with a small WC), and abdominal obesity within healthy ranges of BMI. Changes in BMI and WC were not associated with all-cause and CVD mortality, except for a decrease in WC ≥3.1 cm in the association with all-cause mortality (1.52, 95%CI: 1.01–2.31). Similarly, a decrease in weight ≥3.2 kg was associated with a 1.48 (95%CI: 0.99–2.20) increased all-cause mortality risk. Moreover, both a decrease and an increase in mid-upper arm circumference (MUAC) were associated with all-cause mortality and CVD mortality. A decrease of ≥1.6 cm and 0.6–1.6 cm in MUAC was associated with a 1.81 (95%CI: 1.17–2.79) and a 1.66 (95%CI: 1.10–2.49) all-cause mortality risk. An increase of ≥1.3 cm in MUAC was associated with a 1.52 (95%CI: 1.00–2.31) all-cause mortality risk and a 1.94 (95%CI: 1.00–3.75) CVD mortality risk. In an ageing population, we found that weight gain, especially weight gain of >6 kg, resulted in a decline in QoL. Weight loss (>2 kg) did not result in large changes in QoL. However, both weight gain and weight loss were adversely associated with changes in QoL as compared to a stable weight (changes ≤2 kg). From examination of long-term BMI patterns, the lowest QoL was observed for the ‘persistent obesity (≥30 kg/ m2)’ pattern. The BMI patterns, ‘persistent obesity’, ‘developing overweight (25.0–29.9 kg/m2’, ‘developing obesity’, and ‘switching between BMI categories’ scored 1.8–11.6 points (p<0.05) lower on QoL than the ‘persistent healthy weight (18.5–24.9 kg/m2)’ pattern. The BMI pattern ‘persistent overweight’ generally did not differ from the ‘persistent healthy weight’ pattern. These findings were consistent among age groups.

Conclusions: Although the risk of CHD in the association with BMI attenuated with increasing age, we found associations of BMI and WC with all-cause and cause-specific mortality among the elderly. These anthropometric measures can be used as single predictors of mortality for the elderly, but higher cut-off points for BMI and WC to indicate underweight and excess fat should be considered. Moreover, a combination of these two anthropometric measures can be recommended, as that would provide more information of the body composition than one anthropometric alone. With regard to assessing changes in body composition, MUAC might be recommended for the elderly. Furthermore, a stable weight is best for health maintenance among all ages, provided this stable weight does not fall within the extreme values of weight, i.e. too light or too heavy. In all, our results underscore the value of anthropometric measures in the management of weight and the importance of the maintenance of a stable weight during ageing.

Healthy Ageing: prevention of loneliness among elderly people : evaluation of a complex intervention in public health practice
Honigh - de Vlaming, R. - \ 2013
Wageningen University. Promotor(en): Lisette de Groot; Pieter van 't Veer, co-promotor(en): Annemien Haveman-Nies. - S.l. : s.n. - ISBN 9789461735041 - 214
ouderen - verouderen - levensomstandigheden - sociale integratie - sociologie - interventie - volksgezondheid - nederland - elderly - aging - living conditions - social integration - sociology - intervention - public health - netherlands

Concerns about the ageing population and formal responsibilities of local governments to promote social cohesion and to enhance participation of vulnerable groups in society placed loneliness prevention high on the local policy agenda of Dutch municipalities in the past decade. The study described in this thesis was part of the Healthy Ageing programme of the Academic Collaborative Centre AGORA and aimed to contribute to more effective, evidence-based and problem-oriented approaches to healthy ageing at the local level.

The general aim of this thesis was to evaluate the effectiveness of a local intervention project – called Healthy Ageing – targeting loneliness among non-institutionalised elderly people. Healthy Ageing consisted of five intervention components, namely, a mass media campaign, information meetings, psychosocial group courses, social activities organised by neighbours, Neighbours Connected, and training of intermediaries.

First, the influence of socio-demographic and health characteristics on changes in loneliness over time and municipal differences in the prevalence of loneliness were investigated. Data were gathered from 9,641 persons who participated in the Elderly Health Survey of the community health service, GGD Noord- en Oost- Gelderland (former GGD Gelre-IJssel), in 2005 or 2010. Second, the overall-effect of Healthy Ageing on the initial outcome loneliness literacy, intermediate outcome social support, and ultimate outcome loneliness was evaluated using a quasi-experimental pre-test post-test design, including an intervention and control community. Baseline and follow-up measurements, in 2008 and 2010 respectively, were available for 858 non-institutionalized elderly people. The Loneliness Literacy Scale was developed within the context of this thesis and was pre-tested in a separate study among 303 elderly persons who also participated in the quasi-experimental study. Finally, delivery, reach, and acceptance of the individual intervention components was studied in several satellite studies. Data were collected by different means, e.g. project records and surveys among participants. Furthermore, the acceptability of the mass media communication materials, information meetings, and psychosocial courses of Healthy Ageing was studied by in-depth interviews with 14 clients of the meal delivery service in the intervention community.

Overall and across municipalities, average loneliness scores did not significantly differ between 2005 and 2010. However, among the subgroup with mobility disabilities, loneliness was significantly higher in 2010. Furthermore, mobility disabilities and marital status were the most important factors explaining differences between municipalities. With regard to the evaluation of Healthy Ageing, the satellite studies showed that the reach and intensity of the intervention components were modest. Furthermore, from the interviews it appeared that the mass media communication materials were not successful in attracting attention because interviewees did not expect health information from these communication channels, the perceived personal relevance of the message was low, and the presentation was not attractive. Moreover, the content of the intervention components was not well received because the objectives and intervention components did not connect well with the priority group’s daily life. In addition, it appeared from the quasi-experimental study that 39% of the study participants from the intervention community was familiar with Healthy Ageing at follow-up. Overall, the intervention group scored more favourably on the loneliness literacy subscales, motivation (4.4%), perceived social support (8.2%), and subjective norm (11.5%) than the control group. However, no overall effects were observed for the intermediate and ultimate outcomes, total social support and loneliness after two years.

Given the modest overall intervention exposure, the effect of Healthy Ageing on the loneliness literacy subscale, motivation, is plausible, whereas on the subscales, perceived social support and subjective norm, probable, and on the subscale, self-efficacy, unlikely. Furthermore, whether the initial effects will carry forward to the intermediate and ultimate outcomes needs to be confirmed. The modest effects of Healthy Ageing can partly be explained by the challenges on organisational level which delayed and suppressed project implementation. Furthermore, the project might have benefited from a more systematic approach in order to ensure better alignment between the intervention components and formulated objectives. Finally, target group differentiation is highly recommended. This evaluation of Healthy Ageing illustrates how researchers can cope with the evaluation challenges of complex interventions which cannot be fully controlled. In turn, this provides valuable lessons for the development of intervention programmes and evaluation designs in public health practice.

Mitofood conference : bioactive food components, energy metabolism and human health, 13-15 April 2011, Wageningen, The Netherlands : celebrating 90 years of human and animal physiology at Wageningen University : final conference of COST Action FA0602: bioactive food components, mitochondrial function and health
Keijer, J. - \ 2011
[Wageningen] : Wageningen UR - 87
voedselsamenstelling - bioactieve verbindingen - voedingsstoffen - energiemetabolisme - gezondheid - polyfenolen - lipiden - vitaminen - hormonen - verouderen - bio-energetica - mitochondria - voeding - food composition - bioactive compounds - nutrients - energy metabolism - health - polyphenols - lipids - vitamins - hormones - aging - bioenergetics - nutrition
Towards salutogenichealth promotion : organizing healthy ageing programs at the local level
Lezwijn, J. - \ 2011
Wageningen University. Promotor(en): Cees van Woerkum, co-promotor(en): Lenneke Vaandrager; Annemarie Wagemakers. - [S.l.] : S.n. - ISBN 9789085859864 - 200
gezondheidsbevordering - voorzieningen tbv de gezondheid op regionaal niveau - gezondheidsprogramma's - ouderen - verouderen - health promotion - community health services - health programs - elderly - aging
Als gevolg van landelijke wetgeving, zoals de Wet Publieke Gezondheid (WPG) en de Wet Maatschappelijke Ondersteuning (WMO), hebben gemeenten meer verantwoordelijkheden gekregen ten aanzien van hun oudere populatie. Het onderzoek beschreven in het proefschrift ‘Towards salutogenic health promotion. Organizing healthy ageing programs at the local level’ moet bijdragen aan het opdoen van kennis over hoe lokale programma’s ten behoeve van gezond ouder worden te ontwikkelen, te implementeren en te evalueren. Drie punten bleken belangrijk bij het ontwikkelen, implementeren en evalueren van gezondheidsprogramma’s voor gezond ouder worden. De perceptie van ouderen zelf: De ideeën die ouderen zelf hebben ten aanzien van gezond ouder worden zijn belangrijk. Een salutogene benadering biedt handvaten om de perceptie van ouderen ten aanzien van nieuwe gezondheidsprogramma’s te onderzoeken. Samenwerken voor gezond ouder worden. Samenwerken draagt bij aan het opbouwen van kennis nodig om gezondheidsprogramma’s te ontwikkelen. Samenwerking is echter niet vanzelfsprekend. Daarom zou samenwerking een expliciet onderdeel moeten zijn van gezondheidsprogramma’s. Combineren van bewijs. Door samenwerking met verschillende partijen is het mogelijk om verschillende vormen van bewijs te combineren. Een voorbeeld hiervan is het programma ‘Voor Elkaar in de Buurt’.
Healthy aging in complex environments : exploring the benefits of systems thinking for health promotion practice
Naaldenberg, J. - \ 2011
Wageningen University. Promotor(en): Maria Koelen; Cees Leeuwis, co-promotor(en): Lenneke Vaandrager. - S.l. : s.n. - ISBN 9789085859123 - 208
verouderen - welzijn - gezondheidsbevordering - methodologie - efficiëntie - aging - well-being - health promotion - methodology - efficiency

Many different stakeholders and contextual factors influence the success or failure of health promotion activities. Conventional approaches and evaluation designs underlying health
promotion interventions, often explicitly take contextual variables out of consideration by
controlling them. In doing so, relevant information about why a project was successful or
failed to reach success remains invisible and ‘black boxed’. Next to this, in health promotion
practice, control over contextual variables often is not possible.
Given the complexity of health promotion practice, research approaches often do not fit the realities of practice. As a result, health promotion activities are not always experienced as meaningful by all stakeholders involved. This thesis aims to appreciate the complex environment in which health promotion takes place by applying a systems
thinking perspective to healthy aging in order to contribute to more robust strategies and
interventions to support the aging population.
Systems thinking aims to include a diversity of viewpoints on an issue. Therefore, to be
able to answer the research questions, multiple methods were required. A combination of
literature review, semi-structured and open interviews, interactive workshops, case study
and survey research was used. Different sources for data collection included the aging
population, local and national stakeholders, and AGORA project members.
Part I of this thesis concludes that a systems thinking approach strengthens health promotion by 1) including diverse stakeholder perspectives, 2) explicitly addressing contextual factors, and 3) co-creating solutions with all involved.
Following this conclusion, Part II addressed the application of systems thinking at the local level by investigating different stakeholders perspectives on healthy aging. Results show how there is a discrepancy between the way aging individuals experience healthy aging as an integral part of everyday life and the way services and interventions are presented with a focus on isolated health themes. Local healthy aging strategies can benefit by taking into account an assets based approach that better matches aging persons’ perspectives. Next to this, collaboration between local stakeholders can be facilitated when shared issues are made visible and contextual preconditions are taken into account. Since the operationalization of systems thinking in health promotion can benefit from learning experiences with application in practice, findings from Part II were discussed in interactive presentations and workshop formats within participating municipalities. This resulted in the co-creation of a model to facilitate collaboration and the co-creation
of an intervention through application of this model. The salutogenic concept Sense of
Coherence was identified as a promising concept to operationalize systems approaches
in health promotion practice. It was therefore expected that quantitative measurement of
SOC could provide useful information for both the development and evaluation of health
promotion. The OLQ-13 scale to measure Sense of Coherence was therefore investigated for its psychometric properties. Results indicate difficulties with the use of this scale in aging
populations. Deleting two items from the original 13 items, improved the functioning of OLQ.
The importance of the fact that health issues and possible intervention strategies are perceived differently by involved actors was argued within this thesis. Research is one amongst many stakeholders and a systems thinking approach implies linking all kinds of
actors in order to enable co-creation of projects. Consequently, the definition of health
risks, health determinants, and possible intervention effects have to be verified in both
scientific research and everyday practice.
Strategies to improve health are context sensitive, and consequently, certain strategies may not work in some settings whereas they function perfectly well in others. Measurement of successes of interventions should therefore use multi-method evaluations combining
the use of quantitative and qualitative approaches to gain insight in the ‘black box’ of why
an intervention failed or was successful. If not, alternatives are overlooked and at the same
time successes may go unnoticed.

Social relationships and healthy ageing : epidemiological evidence for the development of a local intervention programme
Croezen, S. - \ 2010
Wageningen University. Promotor(en): Pieter van 't Veer; Lisette de Groot, co-promotor(en): Annemien Haveman-Nies. - [S.l. : S.n. - ISBN 9789085856917 - 128
gezondheid - verouderen - ouderen - sociale participatie - interventie - gezondheid op regionaal niveau - gemeenschapsprogramma's - gezondheidsbeleid - sociale relaties - health - aging - elderly - social participation - intervention - community health - community programs - health policy - social relations
In view of the growing number of older people in our society and the related consequences for health and well-being, research focussing on healthy ageing is essential. Already, the associations between supportive social relationships and healthy ageing have been established. However, there is as yet no consensus about whether or not it is the structure of the social network, its function- ing or a combination that is most important for health, and in addition, about which aspects of structure and function are important.

The main objective of this thesis was to investigate aspects of the structure and functioning of social relationships and their influence on mental, physical and social health in older people. This was relevant to obtain scientific evidence for practice-based research to support local policy making on healthy ageing.

Different characteristics and functions of social relationships, such as frequency of contact, different sources of social network ties, satisfaction with relationships, positive and negative perceptions of social support and social engagement have been analysed in cross-sectional and prospective studies. Cross-sectional data are from six community health services in the eastern part of the Netherlands. The overall sample size constituted of 24,936 people aged 65 and over (response 79%). Prospective data are from the Doetinchem Cohort Study. The first examination round (1987-1991) comprised 12,448 men and women aged 20 to 59 years. The overall response rate was 62% for the baseline measurement and 79%, 75% and 78% for rounds 2, 3 and 4 respectively.

Cross-sectional analyses showed that satisfaction with the social contacts was strongly related to physical (OR 2.36; 95% CI 2.11-2.64), mental (OR 4.65; 95% CI 4.20-5.15) and self-perceived health (OR 2.52; 95% CI 2.29-2.78). Longitudinal analyses underlined this finding by showing that unfavourable levels of social support were predictive for health-compromising behaviours and poor health over a 10-year period of follow-up, and for increased mortality risk over a 15- year period of follow-up (HR 1.57; 95% CI 1.03-2.39). Furthermore, neighbours were found to be an important source of the social network ties of older people in relation to physical (OR 1.87; 95% CI 1.68-2.07), mental (OR 1.53; 95% CI 1.39-1.69) and self-perceived health (OR 1.42; 95% CI 1.30-1.54).

Further exploration of the relationship between social support and loneliness using structural equation modelling identified that social support in everyday situations may serve as a good start- ing point for health promotion activities to prevent loneliness. To better target health promotion activities for healthy ageing, analyses were performed to group older people into subgroups with similar social engagement activity patterns. Five clusters were identified: 1) less socially engaged elderly; 2) less socially engaged caregivers; 3) socially engaged caregivers; 4) leisure-engaged elderly; and 5) productive-engaged elderly. Older people who were not engaged in any social activity other than the care for a sick person, were identified as a possible target group, given the relatively high share of unhealthy people among them. In this non-socially engaged target group, the prevalence of loneliness was 48%, compared to 30% in the socially engaged groups; poor self-perceived health: 41% compared to 14%; poor mental health: 25% compared to 9%; poor physical health: 27% compared to 2%.

Well-functioning social relationships were favourably associated with health. By integrating all results, the local data have strengthened the scientific evidence-base for local policy making and have contributed to the development of an evidence-based community intervention supporting social participation among older people.
Fish fatty acids and mental health in older people
Rest, O. van de - \ 2009
Wageningen University. Promotor(en): Lisette de Groot; Frans Kok, co-promotor(en): Marianne Geleijnse. - [S.l. : S.n. - ISBN 9789085854715 - 200
geestelijke gezondheid - mentale vaardigheid - depressie - visoliën - meervoudig onverzadigde vetzuren - ouderen - verouderen - omega-3 vetzuren - mental health - mental ability - depression - fish oils - polyenoic fatty acids - elderly - aging - omega-3 fatty acids
It has been suggested that the intake of fish and marine n-3 polyunsaturated fatty acids could protect against age-related cognitive decline and impaired mental well-being. However, results from observational studies are inconclusive and data from randomized controlled trials in older people without clinical dementia or depression are scarce. The objective of this thesis was to investigate the effect of daily supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cognitive performance and mental well-being in an older non-clinical population. We also examined the effect of fish oil on gene expression profiles in white blood cells to identify early changes in pathways possibly related to mental health. Furthermore, we assessed the association of fish and EPA+DHA intake with mental health in different aging populations.

The effect of low and high doses of EPA+DHA (400 and 1,800 mg per day, respectively) on cognitive performance, several measures of mental well-being, and gene expression was examined in a 26-week randomized, double-blind, placebo-controlled trial. This study was conducted in 302 individuals aged 65 years or older with no clinical diagnosis of dementia or depression. Furthermore, the cross-sectional association between fatty fish and EPA+DHA intake with cognitive performance and the association with cognitive change during 6 years of follow-up was assessed in 1,025 aging US men who participated in the Veterans Affairs Normative Aging Study (NAS). In addition, the associations of EPA+DHA and fish intake with depressive symptoms and dispositional optimism were assessed in 644 free-living Dutch subjects with a history of myocardial infarction.

Daily intake of low or high doses of EPA+DHA did not affect cognitive performance, mental well-being, anxiety, or quality of life, after 13 or 26 weeks of intervention. However, treatment with EPA+DHA for 26 weeks altered gene expression in white blood cells to a more anti-inflammatory and more anti-atherogenic profile. In elderly US men we found no association of fatty fish or EPA+DHA intake with cognitive performance or 6-year cognitive change. Intake of EPA+DHA was positively associated with dispositional optimism in subjects with a history of myocardial infarction. There was also a tendency for less depressive symptoms with a higher EPA+DHA or fish intake, but this association was no longer statistically significant after controlling for confounders.

Supplemental intake of EPA+DHA is unlikely to have a short-term impact on cognitive performance or mental well-being of older people without a clinical diagnosis of dementia or depression. Whether long-term intake of EPA+DHA and fish could be beneficial to the maintenance of cognitive performance or mental well-being of older people in Western populations still needs to be established.
Time dependence in jamming and unjamming
Parker, A. - \ 2009
Wageningen University. Promotor(en): Erik van der Linden. - [S.l. : S.n. - ISBN 9789085853879 - 99
gels - stabiliteit - dynamica - reologie - verouderen - sedimentatie - thixotropie - verarming - uitvlokking - xanthan - gelatine - evenwicht - stability - dynamics - rheology - aging - sedimentation - thixotropy - depletion - flocculation - gelatin - equilibrium
Three different food systems have been studied: emulsion/polymer mixtures, gelatin gels and carrageenan gels. Typically, samples are trapped, or jammed, far from equilibrium. The simple jamming paradigm suggests that, once in the jammed state, these systems are static. This useful approximation is often too simple, since these systems frequently evolve in time. Their evolution has been measured systematically. Where possible, these results have been placed in the context of the physics of out-of-equilibrium systems.
The emulsion/polymer mixtures are a model for salad dressing. The emulsions alone are colloidally stable, but become inhomogeneous, due to the effects of gravity. With sufficient polymer, they can be apparently stable (jammed) for months, but then quite suddenly start to sediment – the system unjams. The kinetics of this delayed sedimentation is measured as a function of the key parameters. A new model is proposed for the mechanism by which polymers stabilize emulsions.
Solutions of gelatin form gels when cooled, due to the formation of portions of helix. A new model relating the amount of helix to the elasticity is described. The gels always evolve slowly. At steady state, the rate of evolution of the elasticity is constant in log(time), so this system conforms to Struick’s physical aging scenario. The effect of temperature changes on the evolution of gels is extremely complex. The results show that there is a deep analogy between this behavior and that of spin glasses, which are exotic magnetic phases.
Gels of iota carrageenan, a seaweed polysaccharide, have unique rheological properties: they regel almost instantly after strong mixing. This property is used in the dairy industry, but has not been studied previously. The kinetics of recovery after shear has been measured for water gels and milk gels.

Food for the ageing population
Raats, M.M. ; Groot, C.P.G.M. de; Staveren, W.A. van - \ 2008
London : Woodhead Publishing (Woodhead publishing in food science, technology and nutrition ) - ISBN 9781845691936 - 652
ouderenvoeding - ouderen - ouderdom - verouderen - elderly nutrition - elderly - old age - aging
The world’s ageing population is increasing and food professionals will have to address the needs of older generations more closely in the future. This unique volume reviews the characteristics of the ageing population as food consumers, the role of nutrition in healthy ageing and the design of food products and services for the elderly. Chapters in Part one discuss aspects of the elderly’s relationship with food such as appetite and ageing, ageing and sensory perception, food and satisfaction with life, and the social significance of meals. The second part of the book reviews the role of nutrition in extending functionality into later years, with chapters on topics such as undernutrition and conditions such as Alzheimer's disease, bone and joint health and eye-related disorders. Concluding chapters address the issues of food safety and the elderly, designing new foods and beverages for the ageing and nutrition education programmes.
Voeding en gezond ouder worden
Groot, C.P.G.M. de; Visser, M. de - \ 2008
Voeding Nu 10 (2008)12. - ISSN 1389-7608 - p. 34 - 34.
verouderen - humane voeding - voedingsonderzoek - overgewicht - ondergewicht - ouderen - voeding en gezondheid - aging - human feeding - nutrition research - overweight - underweight - elderly - nutrition and health
Door de toenemende vergrijzing is meer aandacht voor de voedingsproblemen van ouderen noodzakelijk. Een slechte nutriëntenstatus en onder- of overgewicht als gevolg van een disbalans tussen energie-inneming en -verbruik komen vaak voor. De omvang en gevolgen van deze voedingsproblemen worden in dit artikel kort besproken
Productivity and resource use in ageing tea plantations
Kamau, D.M. - \ 2008
Wageningen University. Promotor(en): Huub Spiertz; Oene Oenema, co-promotor(en): P.O. Owuor. - [S.l.] : S.n. - ISBN 9789085048084 - 140
camellia sinensis - thee - gewasproductie - gewasopbrengst - verouderen - bodemvruchtbaarheid - stikstofbalans - voedingsstoffen - kringlopen - kenya - tea - crop production - crop yield - aging - soil fertility - nitrogen balance - nutrients - cycling
Keywords: Kenya, Camellia sinensis L., clones, seedlings, tea industry, management, N-P-K, biomass, made tea yields.

The tea industry in Kenya is rural-based and provides livelihood to over three million people along the value chain. The industry which started in the first quarter of the 20th century has continued to increase in terms of production and total acreage. Tea is grown in prime agricultural and forest land and can be in production for up to 100 years if well managed. However, peak yields are obtained at 20–40 years after planting followed by a decline to a level where the plantations may become degraded and uneconomical. In the past, several hypotheses have been postulated, but the cause of this degradation largely remains unclear. The big question still lingers, is it the tea bush that degrades, the soil or both?
In this study, trends in tea yields were first assessed by analysing long-term tea production data, from 1969 to 2006, for the two sectors of the Kenyan tea industry. The plantations are characterized by differences in age and genotypes (seedling or clonal). To explore plausible management options for tea productivity improvement, a simple decision-support (DS) model for Managing Ageing Plantations of Tea (MAP-Tea) was developed and scenario analyses were done to explore some promising management interventions. It was found that uprooting and replanting of degraded old seedling tea plantations with clonal cultivars would be profitable. However, management practices that prevent degradation are most cost effective.
The experimental part of the study was carried out during two years, 2002/2003 and 2003/2004, in a chronosequence of existing tea plantations (14, 29, 43 and 76 years old), adjacent to a natural forest in Kericho, Kenya. Soil-plant-environment relations and effects on tea bush productivity, C and N-P-K stocks and soil quality traits were analysed. Younger clonal tea plantations established at high densities outyielded the older seedling plantations with a lower densities. Ageing per se did not reduce the N-response or the productivity of tea plantations. It was shown that seedling tea bushes acquire much higher C and N-P-K nutrient stocks with age than clonal bushes. This may enable seedling plantations to depend less on limiting nutrient(s) supply under adverse conditions, i.e. drought. The top soils of the four tea plantations showed small differences in chemical and biological characteristics, also in comparison to the natural forest. Soil pH and total organic carbon were weakly related to the productivity of the ageing tea plantations. Additions of tea prunings in incubated soils caused immobilization of N and lowered the net N-mineralization compared to the forest soil, but the differences were relatively small and unlikely to cause degradation of the ageing tea plantations. Further improvement in productivity and resource use of ageing tea plantations should come from a better timing and dosing of nitrogen, and from the transition from old low-yielding seedling plantations to modern higher-yielding clonal plantations taking into account Genotype × Environment × Management (G×E×M) relationships.

Dietary patterns, biological risk factors and survival in elderly European men and women
Knoops, K.T.B. - \ 2007
Wageningen University. Promotor(en): Wija van Staveren; Daan Kromhout, co-promotor(en): Lisette de Groot. - [S.l.] : S.n. - ISBN 9789085046912 - 208
dieet - risicofactoren - risicoschatting - mortaliteit - overleving - voedingstoestand - voeding - ouderen - ouderdom - verouderen - europa - diet - risk factors - risk assessment - mortality - survival - nutritional state - nutrition - elderly - old age - aging - europe
Background: The percentage of the population aged 65 and over, which started to rise sharply in the last decades of the past century, is continuing to rise. However, up until now, little is known about dietary factors and diet-related biological factors in elderly in relation to survival in old age. Aim: The aim of this thesis is to investigate the associations between dietary patterns, diet-related biological risk factors and survival. Study population: Data from two prospective studies were used, the Healthy Ageing: a longitudinal study in Europe (HALE) and the Normative Aging Study (NAS). The HALE project which involves individuals enrolled in the Survey in Europe on Nutrition and the Elderly: a Concerned Action (SENECA) and the Finland, Italy, the Netherlands, Elderly (FINE) studies, includes 1507 apparently healthy men and 832 women in 11 European Countries, aged 70 to 90 years at baseline and who were followed for 10 years. The NAS is a longitudinal study which started in 1963 by recruiting men, 21 to 80 years of age and free of heart disease and other major health problems, around Boston. Data collected in 1993 and later were used. Results: We observed that after fortification with folic acid, folate intake and plasma folate concentration increased significantly in three groups with different dietary patterns, derived by cluster analysis. Homocysteine tended to decrease in the group with a relatively high alcohol consumption, low fruit and vegetable dietary pattern in the NAS study. Dietary patterns defined by three European indexes were significantly associated with all-cause mortality in the HALE project. A Mediterranean type of diet was associated with an approximately 20 % lower mortality rates in both apparently healthy elderly and in post-myocardial infarction patients. Healthy lifestyle factors (moderate alcohol consumption, being physically active and non-smoking) were also inversely associated with all-cause mortality. Weight loss was significantly associated with increased all-cause mortality in the study centres of Northern Europe while weight gain was weakly associated with increased mortality in these centres in the FINE study. HDL-cholesterol was inversely associated with mortality from cardiovascular diseases and all-causes in the HALE project. Associations between HDL and mortality were strongest in women. Conclusion: A healthy diet is associated with lower mortality risk in elderly. Besides a healthy diet, it is important for elderly people to be physically active, use alcohol in moderation and quit smoking. It is also important to maintain constant body weight and to keep blood cholesterol at a desirable level, especially to keep HDL-cholesterol high.
Voeding versus veroudering
Groot, C.P.G.M. de - \ 2006
VoedingsMagazine 19 (2006)3. - ISSN 0922-8012 - p. 8 - 10.
humane voeding - ouderen - ouderenvoeding - gezondheid - voedingstoestand - verouderen - organisatie van onderzoek - human feeding - elderly - elderly nutrition - health - nutritional state - aging - organization of research
In her inaugural speech when accepting the office of professor by special appointment at Wageningen University, Lisette de Groot unfolds her intentions. Research on all levels (from descriptive research on a population level and individual interventions to studies on a cellular level) should bring a bit closer the target goal of curbing functional decline as a consequence of ageing processes
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