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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    Changes in body composition during and after adjuvant or neo-adjuvant chemotherapy in women with breast cancer stage I–IIIB compared with changes over a similar timeframe in women without cancer
    Berg, M.M.G.A. van den; Kok, D.E. ; Visser, M. ; Vries, J.H.M. de; Kruif, J.T.C.M. de; Vries, Y. de; Posthuma, L. ; Sommeijer, D.W. ; Timmer-Bonte, A. ; Los, M. ; Laarhoven, H.W.M. van; Kampman, E. ; Winkels, Renate M. - \ 2020
    Supportive Care in Cancer 28 (2020). - ISSN 0941-4355 - p. 1685 - 1693.
    Body composition - Body weight - Breast cancer - Chemotherapy

    Purpose: Body weight and body composition may change during and after adjuvant or neo-adjuvant chemotherapy for breast cancer. However, most studies did not include a comparison group of women without cancer, thus could not assess whether observed changes differed from age-related fluctuations in body weight and body composition over time. We assessed changes in body composition during and after chemotherapy in breast cancer patients compared with age-matched women not diagnosed with cancer. Methods: We recruited 181 patients with stage I–IIIb breast cancer and 180 women without cancer. In patients, we assessed body composition using a dual-energy X-ray scan before start of chemotherapy (T1), shortly after chemotherapy (T2), and 6 months after chemotherapy (T3); for the comparison group, the corresponding time points were recruitment (T1) and 6 (T2) and 12 (T3) months. Results: Fifteen percent of patients and 8% of the comparison group gained at least 5% in body weight between T1 and T3. Among the comparison group, no statistically significant changes in body weight, or body composition were observed over time. Body weight of patients significantly increased from baseline (72.1 kg ± 0.4 kg) to T2 (73.3 kg ± 0.4 kg), but decreased to 73.0 kg ± 0.4 kg after chemotherapy (T3). Lean mass of patients significantly increased from 43.1 kg ± 0.5 kg at baseline to 44.0 kg ± 0.5 kg at T2, but returned to 43.1 kg ± 0.5 kg at T3. There were no differential changes in fat mass over time between patients and the comparison group. Conclusions: Changes in body weight and body composition during and after chemotherapy for early stage breast cancer were modest, and did not differ substantially from changes in body weight and body composition among women without cancer.

    Folic acid and Vitamin B12 supplementation and the risk of cancer : Long-term Follow-up of the B Vitamins for the Prevention of Osteoporotic Fractures (B-PROOF) Trial
    Araghi, Sadaf Oliai ; Kiefte-De Jong, Jessica C. ; Dijk, Suzanne C. Van; Swart, Karin M.A. ; Laarhoven, Hanneke W. van; Schoor, Natasja M. van; Groot, Lisette C.P.G.M. de; Lemmens, Valery ; Stricker, Bruno H. ; Uitterlinden, Andre G. ; Velde, Nathalie Van Der - \ 2019
    Cancer Epidemiology Biomarkers & Prevention 28 (2019)2. - ISSN 1055-9965 - p. 275 - 282.

    Background: Folic acid and vitamin B12 play key roles in one-carbon metabolism. Disruption of one-carbon metabolism may be involved in the risk of cancer. Our aim was to assess the long-term effect of supplementation with both folic acid and vitamin B12 on the incidence of overall cancer and on colorectal cancer in the B Vitamins for the Prevention of Osteoporotic Fractures (B-PROOF) trial. Methods: Long-term follow-up of B-PROOF trial participants (N ¼ 2,524), a multicenter, double-blind randomized placebo-controlled trial designed to assess the effect of 2 to 3 years daily supplementation with folic acid (400 mg) and vitamin B12 (500 mg) versus placebo on fracture incidence. Information on cancer incidence was obtained from the Netherlands cancer registry (Integraal Kankercentrum Nederland), using the International Statistical Classification of Disease (ICD-10) codes C00-C97 for all cancers (except C44 for skin cancer), and C18-C20 for colorectal cancer. Results: Allocation to B vitamins was associated with a higher risk of overall cancer [171 (13.6%) vs. 143 (11.3%); HR 1.25; 95% confidence interval (CI), 1.00-1.53, P ¼ 0.05]. B vitamins were significantly associated with a higher risk of colorectal cancer [43(3.4%) vs. 25(2.0%); HR 1.77; 95% CI, 1.08-2.90, P ¼ 0.02]. Conclusions: Folic acid and vitamin B12 supplementation was associated with an increased risk of colorectal cancer. Impact: Our findings suggest that folic acid and vitamin B12 supplementation may increase the risk of colorectal cancer. Further confirmation in larger studies and in meta-analyses combining both folic acid and vitamin B12 are needed to evaluate whether folic acid and vitamin B12 supplementation should be limited to patients with a known indication, such as a proven deficiency.

    Changes in Circulating Levels of 25-hydroxyvitamin D3 in Breast Cancer Patients Receiving Chemotherapy
    Kok, Dieuwertje E. ; Berg, Maaike M.G.A. van den; Posthuma, Liesbeth ; ’t Erve, Iris van; Duijnhoven, Fränzel J.B. van; Roos, Wilfred K. de; Grosfeld, Sissi ; Los, Maartje ; Sommeijer, Dirkje W. ; Laarhoven, Hanneke W.M. van; Winkels, Renate M. ; Kampman, Ellen - \ 2019
    Nutrition and Cancer 71 (2019)5. - ISSN 0163-5581 - p. 756 - 766.

    Cancer treatments, toxicities and their effects on lifestyle, may impact levels of vitamin D. The aim of this study was to determine serum 25-hydroxyvitamin D3 (25(OH)D3) levels before, directly after and 6 months after chemotherapy in breast cancer patients (n = 95), and a comparison group of women (n = 52) not diagnosed with cancer. Changes in 25(OH)D3 levels over time were compared using linear mixed models adjusted for age and season of blood sampling. Before start of chemotherapy, 25(OH)D3 levels were lower in patients (estimated marginal mean 55.8 nmol/L, 95% confidence interval (95%CI) 51.2–60.4) compared to the comparison group (67.2 nmol/L, 95%CI 61.1–73.3, P = 0.003). Directly after chemotherapy, 25(OH)D3 levels were slightly decreased (–5.1 nmol/L, 95%CI –10.7–0.5, P = 0.082), but ended up higher 6 months after chemotherapy (10.9 nmol/L, 95%CI 5.5–16.4, P < 0.001) compared to pre-chemotherapy values. In women without cancer, 25(OH)D3 levels remained stable throughout the study. Use of dietary supplements did not explain recovery of 25(OH)D3 levels after chemotherapy. We reported lower 25(OH)D3 levels in breast cancer patients, which decreased during chemotherapy, but recovered to levels observed in women without cancer within 6 months after chemotherapy. Suboptimal 25(OH)D3 levels in the majority of the participants highlight the relevance of monitoring in this vulnerable population.

    A longitudinal mixed methods study on changes in body weight, body composition, and lifestyle in breast cancer patients during chemotherapy and in a comparison group of women without cancer : Study protocol
    Kruif, J.Th.C.M. De; Visser, M. ; Berg, M.M.G.A. Van Den; Derks, M.J.M. ; Boer, M.R. De; Laarhoven, H.W.M. Van; Vries, J.H.M. De; Vries, Y.C. De; Kampman, E. ; Winkels, R.W. ; Westerman, M.J. - \ 2019
    BMC Cancer 19 (2019)1. - ISSN 1471-2407
    Body composition - Body weight - Breast cancer - Dietary intake - Mixed methods - Perceptions - Physical activity - Quality of life

    Background: More than 60% of women diagnosed with early stage breast cancer receive (neo)adjuvant chemotherapy. Breast cancer patients receiving chemotherapy often experience symptoms such as nausea, vomiting and loss of appetite that potentially affect body weight and body composition. Changes in body weight and body composition may detrimentally affect their quality of life, and could potentially increase the risk of disease recurrence, cardiovascular disease and diabetes. To date, from existing single method (quantitative or qualitative) studies is not clear whether changes in body weight and body composition in breast cancer patients are treatment related because previous studies have not included a control group of women without breast cancer. Methods: We therefore developed the COBRA-study (Change Of Body composition in BReast cancer: All-in Assessment-study) to assess changes in body weight, body composition and related lifestyle factors such as changes in physical activity, dietary intake and other behaviours. Important and unique features of the COBRA-study is that it used I) a "Mixed Methods Design", in order to quantitatively assess changes in body weight, body composition and lifestyle factors and, to qualitatively assess how perceptions of women may have influenced these measured changes pre-, during and post-chemotherapy, and II) a control group of non-cancer women for comparison. Descriptive statistics on individual quantitative data were combined with results from a thematic analysis on the interviews- and focus group data to understand patients' experiences before, during and after chemotherapy. Discussion: The findings of our mixed methods study, on chemotherapy treated cancer patients and a comparison group, can enable healthcare researchers and professionals to develop tailored intervention schemes to help breast cancer patients prevent or handle the physical and mental changes they experience as a result of their chemotherapy. This will ultimately improve their quality of life and could potentially reduce their risk for other co-morbidity health issues such as cardiovascular disease and diabetes.

    Body composition is associated with risk of toxicity-induced modifications of treatment in women with stage I–IIIB breast cancer receiving chemotherapy
    Berg, Maaike M.G.A. van den; Kok, Dieuwertje E. ; Posthuma, Liesbeth ; Kamps, Lisette ; Kelfkens, Celine S. ; Buist, Nicole ; Geenen, Maud ; Haringhuizen, Annebeth ; Heijns, Joan B. ; Lieshout, Rianne H.M.A. van; Los, Maartje ; Sommeijer, Dirkje W. ; Timmer-Bonte, Johanna N.H. ; Kruif, Anja Th.C.M. de; Laarhoven, Hanneke W.M. van; Kampman, Ellen ; Winkels, Renate M. - \ 2019
    Breast Cancer Research and Treatment 173 (2019)2. - ISSN 0167-6806 - p. 475 - 481.
    Body composition - Breast cancer - Chemotherapy - Fat mass - Toxicity

    Purpose: Initial dose of chemotherapy is planned based on body surface area, which does not take body composition into account. We studied the association between fat mass (kg and relative to total body weight) as well as lean mass (kg and relative to total body weight) and toxicity-induced modifications of treatment in breast cancer patients receiving chemotherapy. Methods: In an observational study among 172 breast cancer patients (stage I–IIIB) in the Netherlands, we assessed body composition using dual-energy X-ray scans. Information on toxicity-induced modifications of treatment, defined as dose reductions, cycle delays, regimen switches, or premature termination of chemotherapy, was abstracted from medical records. Adjusted hazard ratios and 95% confidence intervals (95% CI) were calculated to assess associations between body composition and the risk of toxicity-induced modifications of treatment. Results: In total, 95 out of 172 (55%) patients experienced toxicity-induced modifications of treatment. Higher absolute and relative fat mass were associated with higher risk of these modifications (HR 1.14 per 5 kg; 95% CI 1.04–1.25 and HR 1.21 per 5%; 95% CI 1.05–1.38, respectively). A higher relative lean mass was associated with a lower risk of modifications (HR 0.83 per 5%; 95% CI 0.72–0.96). There was no association between absolute lean mass and risk of toxicity-induced modifications of treatment. Conclusions: A higher absolute and a higher relative fat mass was associated with an increased risk of toxicity-induced modifications of treatment. Absolute lean mass was not associated with risk of these treatment modifications, while higher relative lean mass associated with lower risk of modifications. These data suggest that total fat mass importantly determines the risk of toxicities during chemotherapy in breast cancer patients.

    Low reported taste function is associated with low preference for high protein products in advanced oesophagogastric cancer patients undergoing palliative chemotherapy
    Vries, Y.C. de; Boesveldt, S. ; Kampman, E. ; Graaf, C. de; Winkels, R.M. ; Laarhoven, H.W.M. van - \ 2019
    Clinical Nutrition 38 (2019)1. - ISSN 0261-5614 - p. 472 - 475.
    Cancer - Chemotherapy - Food preferences - Smell - Taste
    Background & aims: Cancer patients undergoing palliative chemotherapy can experience a variety of chemosensory and food preference changes which may impact their nutritional status and quality of life. However, evidence of these changes in oesophagogastric cancer (OGC) patients is currently mostly qualitative and not supported by quantitative data. The aim of this study was to assess how self-reported and objective taste and smell function and food preferences change over time during chemotherapy in OGC patients. Methods: This observational study included 15 advanced OGC patients planned for first line treatment with capecitabine and oxaliplatin. Participants completed two test sessions scheduled before start of cytotoxic treatment and after two cycles. Self-reported and objective taste and smell function and the macronutrient and taste preference ranking task were conducted at each test session. Results: Self-reported taste and smell did not change upon chemotherapy. Objective taste function decreased during chemotherapy, although this was not statistically significant (p = 0.06), objective smell function did not change. Before and during chemotherapy, high protein foods were preferred over high carbohydrate and over low energy products, but food preferences did not change over time. A lower self-reported taste function correlated with a lower preference for high-protein products (ρ = 0.526, p = 0.003). Conclusion: This study suggests that objective taste function decreases during chemotherapy in OGC patients, but not smell function. A low reported taste function was related to a lower preference for high-protein products.
    Efficacy of oral compared with intramuscular Vitamin B-12 supplementation after Roux-en-Y gastric bypass : A randomized controlled trial
    Schijns, Wendy ; Homan, Jens ; Meer, Leah van der; Janssen, Ignace M. ; Laarhoven, Cees J. van; Berends, Frits J. ; Aarts, Edo O. - \ 2018
    American Journal of Clinical Nutrition 108 (2018)1. - ISSN 0002-9165 - p. 6 - 12.
    cobalamin - deficiencies - Roux-en-Y gastric bypass - RYGB - supplementation - Vitamin B-12

    Background After Roux-en-Y gastric bypass (RYGB), patients often develop a vitamin B-12 deficiency. Objective Our objective was to investigate whether oral supplementation increases and normalizes low vitamin B-12 concentrations (vitamin B-12 > 200 pmol/L) in RYGB patients as compared to intramuscular injections. Design A randomized controlled trial in RYGB patients with subnormal serum B-12 concentrations was performed. One group (IM B-12) received bimonthly intramuscular hydroxocobalamin injections (2000 μg as loading dose and 1000 μg at follow-up) for 6 mo. The second group (oral B-12) received daily doses of oral methylcobalamin (1000 μg). Serum vitamin B-12 was determined at baseline (T0) and at 2 (T1), 4 (T2), and 6 mo (T3) after start of treatment. Concentrations of the secondary markers methylmalonic acid (MMA) and homocysteine (Hcy) were measured at T0 and T3. Results Fifty patients were included and randomized, 27 in IM B-12 and 23 in oral B-12. The median vitamin B-12 concentration at T0 was 175 pmol/L (range: 114-196 pmol/L) for IM B-12 and 167 pmol/L (range: 129-199 pmol/L) for oral B-12. Vitamin B-12 normalized in all individuals, and there was no significant difference in vitamin B-12 between the two groups. MMA and Hcy concentrations decreased significantly after 6 mo within each group (P < 0.001 and P < 0.001 for MMA and P = 0.03 and P = 0.045 for Hcy, respectively). There was no significant difference between the groups at 6 mo for both MMA and Hcy (P = 0.53 and P = 0.79). Conclusion The efficacy of oral vitamin B-12 supplementation was similar to that of hydroxocobalamin injections in the present study. Oral supplementation can be used as an alternative to hydroxocobalamin injections to treat RYGB patients with low values of serum vitamin B-12. This trial was registered at clinicaltrials.gov as NCT02270749.

    Do specialized bariatric multivitamins lower deficiencies after RYGB?
    Schijns, Wendy ; Schuurman, Lisanne T. ; Melse-Boonstra, Alida ; Laarhoven, Cees J.H.M. van; Berends, Frits J. ; Aarts, Edo O. - \ 2018
    Surgery for Obesity and Related Diseases 14 (2018)7. - ISSN 1550-7289 - p. 1005 - 1012.
    Bariatric surgery - Deficiency - Mineral - Multivitamin - Obesity - Roux-en-Y gastric bypass - Specialized - Vitamin
    Background: One of the side effects of bariatric surgery is the risk of vitamin and mineral deficiencies. Vitamin B12, vitamin D, folate, and iron deficiencies are especially common among Roux-en-Y gastric bypass patients. Objective: To examine the effectiveness of a specialized multivitamin supplement for Roux-en-Y gastric bypass patients on deficiencies the first 3 years postoperatively, retrospectively in a large, prospectively collected cohort. Setting: Large specialized bariatric hospital. Results: One thousand one hundred sixty patients were included, 883 users and 258 who were nonusers of the specialized multivitamin. Patient characteristics and total weight were comparable. Higher serum concentrations of ferritin (124.7 ± 96.2 µg/L versus 106.0 ± 83.0 µg/L, P =.016), vitamin B12 (347.3 ± 145.1 pmol/L versus 276.8 ± 131.4 pmol/L, P<.001), folic acid (34.9 ± 9.6 nmol/L versus 25.4 ± 10.7 nmol/L, P<.001), and vitamin D (98.4 ± 28.7 nmol/L versus 90.0 ± 34.5 nmol/L, P =.002) were observed in users compared with nonusers after 1 year. Less new deficiencies were found for ferritin (1% versus 4%, P =.029), vitamin B12 (9% versus 23%, P<.001), and vitamin D (0% versus 4%, P<.001) in users compared with nonusers. Two and 3 years after the surgery these findings remained almost identical. Conclusions: The use of specialized multivitamin supplements resulted in less deficiencies of vitamin B12, vitamin D, folic acid, and ferritin. The study showed that Roux-en-Y gastric bypass patients benefited from the specialized multivitamin supplements and it should be advised to this patient group.
    Taste and smell perception and quality of life during and after systemic therapy for breast cancer
    Vries, Y.C. de; Boesveldt, S. ; Kelfkens, C.S. ; Posthuma, E.E. ; Den Berg, M.M.G.A. van; Kruif, J.T.C.M. de; Haringhuizen, A. ; Sommeijer, D.W. ; Buist, N. ; Grosfeld, S. ; Graaf, C. de; Laarhoven, H.W.M. van; Kampman, E. ; Winkels, R.M. - \ 2018
    Breast Cancer Research and Treatment 170 (2018)1. - ISSN 0167-6806 - p. 27 - 34.
    Breast cancer - Chemotherapy - Dysgeusia - Herceptin - Quality of life - Smell - Taste - Taste loss - Trastuzumab
    Purpose: The purpose of the study was to assess self-reported taste and smell perception after chemotherapy in breast cancer patients compared with women without cancer, and to assess whether taste and smell perception is associated with quality of life after the end of chemotherapy. Methods: We included 135 newly diagnosed breast cancer patients who completed chemotherapy and 114 women without cancer. Questionnaires on taste, smell, and quality of life were completed shortly after and 6 months after chemotherapy (patients) or at two moments with 6 months’ time window in between (comparisons). Results: Self-reported taste and smell perception were significantly lower in patients shortly after chemotherapy compared to the comparison group. Most patients recovered 6 months after chemotherapy, although patients who were still receiving trastuzumab then reported a lower taste and smell perception compared to patients who were not. A lower self-reported taste and smell were statistically significantly associated with a worse quality of life, social, emotional, and role functioning shortly after chemotherapy. Six months after chemotherapy, taste and smell were statistically significantly associated with quality of life, social and role functioning, but only in patients receiving trastuzumab. Conclusions: Most taste and smell alterations recovered within 6 months after the end of chemotherapy for breast cancer, but not for patients receiving trastuzumab. These results highlight the importance of monitoring taste and smell alterations during and after treatment with chemotherapy and trastuzumab, as they may impact quality of life.
    Cerebral tryptophan metabolism and outcome of tuberculous meningitis : An observational cohort study
    Laarhoven, Arjan van; Dian, Sofiati ; Aguirre-Gamboa, Raúl ; Avila-Pacheco, Julian ; Ricaño-Ponce, Isis ; Ruesen, Carolien ; Annisa, Jessi ; Koeken, Valerie A.C.M. ; Chaidir, Lidya ; Li, Yang ; Achmad, Tri Hanggono ; Joosten, Leo A.B. ; Notebaart, Richard A. ; Ruslami, Rovina ; Netea, Mihai G. ; Verbeek, Marcel M. ; Alisjahbana, Bachti ; Kumar, Vinod ; Clish, Clary B. ; Ganiem, A.R. ; Crevel, Reinout van - \ 2018
    The Lancet Infectious Diseases 18 (2018)5. - ISSN 1473-3099 - p. 526 - 535.
    Background: Immunopathology contributes to the high mortality of tuberculous meningitis, but the biological pathways involved are mostly unknown. We aimed to compare cerebrospinal fluid (CSF) and serum metabolomes of patients with tuberculous meningitis with that of controls without tuberculous meningitis, and assess the link between metabolite concentrations and mortality. Methods: In this observational cohort study at the Hasan Sadikin Hospital (Bandung, Indonesia) we measured 425 metabolites using liquid chromatography-mass spectrometry in CSF and serum from 33 HIV-negative Indonesian patients with confirmed or probable tuberculous meningitis and 22 control participants with complete clinical data between March 12, 2009, and Oct 27, 2013. Associations of metabolite concentrations with survival were validated in a second cohort of 101 patients from the same centre. Genome-wide single nucleotide polymorphism typing was used to identify tryptophan quantitative trait loci, which were used for survival analysis in a third cohort of 285 patients. Findings: Concentrations of 250 (70%) of 351 metabolites detected in CSF were higher in patients with tuberculous meningitis than in controls, especially in those who died during follow-up. Only five (1%) of the 390 metobolites detected in serum differed between patients with tuberculous meningitis and controls. CSF tryptophan concentrations showed a pattern different from most other CSF metabolites; concentrations were lower in patients who survived compared with patients who died (9-times) and to controls (31-times). The association of low CSF tryptophan with patient survival was confirmed in the validation cohort (hazard ratio 0·73; 95% CI 0·64-0·83; p<0·0001; per each halving). 11 genetic loci predictive for CSF tryptophan concentrations in tuberculous meningitis were identified (p<0·00001). These quantitative trait loci predicted survival in a third cohort of 285 HIV-negative patients in a prognostic index including age and sex, also after correction for possible confounders (p=0·0083). Interpretation: Cerebral tryptophan metabolism, which is known to affect Mycobacterium tuberculosis growth and CNS inflammation, is important for the outcome of tuberculous meningitis. CSF tryptophan concentrations in tuberculous meningitis are under strong genetic influence, probably contributing to the variable outcomes of tuberculous meningitis. Interventions targeting tryptophan metabolism could improve outcomes of tuberculous meningitis. Funding: Royal Dutch Academy of Arts and Sciences; Netherlands Foundation for Scientific Research; Radboud University; National Academy of Sciences; Ministry of Research, Technology, and Higher Education, Indonesia; European Research Council; and PEER-Health.
    Altered food preferences and chemosensory perception during chemotherapy in breast cancer patients : A longitudinal comparison with healthy controls
    Vries, Y.C. de; Winkels, R.M. ; Berg, M.M.G.A. van den; Graaf, C. de; Kelfkens, C.S. ; Kruif, J.T.C.M. de; Göker, E. ; Grosfeld, S. ; Sommeijer, D.W. ; Laarhoven, H.W.M. Van; Kampman, E. ; Boesveldt, S. - \ 2018
    Food Quality and Preference 63 (2018). - ISSN 0950-3293 - p. 135 - 143.
    Cancer - Chemotherapy - Food preferences - Smell - Taste
    Changes in food preferences and chemosensory function are frequently reported during chemotherapy, but the nature of these changes are largely unknown. We followed and characterized food preferences, taste and smell function over chemotherapy treatment in breast cancer patients and compared to women without cancer. Furthermore, we assessed associations between taste and smell function and food preferences in breast cancer patients. Women with newly diagnosed breast cancer (n = 28) completed test sessions before, halfway, shortly after, and six months after chemotherapy. Twenty-eight women without cancer were tested at similar time points as control. During test sessions, food preferences were assessed with the Macronutrient and Taste Preference Ranking Task. Self-reported taste and smell function were tested on a visual analogue scale. Objective taste and smell function were assessed with Taste Strips and Sniffin’ Sticks. Breast cancer patients liked high-protein, high-fat, sweet, and savoury products less during chemotherapy, which returned to baseline six months after chemotherapy, while the control group was stable over time. Chemotherapy led to a decreased taste and smell function which recovered six months after chemotherapy. A better self-reported taste was associated with higher liking of high-protein, low-energy, savoury and sweet products. Breast cancer patients undergoing chemotherapy have altered food preferences for certain macronutrients, but not specifically for sweet or savoury tastes. Chemotherapy has a transient influence on food preferences and chemosensory function, of which patients should be informed prior to treatment, and which should be monitored during treatment due to the consequences for nutritional intake and quality of life.
    PhD Defence Bob Laarhoven (Event)
    Hendriks, Wouter - \ 2017
    member exam committee public defence Bob Laarhoven
    Valorisation of waste streams from by-product to worm biomass
    Laarhoven, Bob - \ 2017
    Wageningen University. Promotor(en): C.J.N. Buisman, co-promotor(en): B.G.. Temmink; H.J.H. Elissen. - Wageningen : Wageningen University - ISBN 9789463438117 - 141
    biomass - residual streams - animal nutrition - fisheries - organic wastes - helminths - biomassa - reststromen - diervoeding - visserij - organisch afval - wormen

    There is a global demand for more feed resources to keep up with the increasing production of livestock. The hunger for resources is most urgent in the aquaculture sector, which to a large degree depends on the non-sustainable use of fish oil/ meal from wild fish. Aquatic macro invertebrates such as the freshwater worm Lumbriculus variegatus (Oligochaeta, Lumbriculidae, common name blackworms, further abbreviated as Lv) are rich in proteins, lipids, vitamins and minerals. When cultivated on safe and low-grade organic wastes they can provide a sustainable fishmeal alternative for most freshwater and marine fish.

    Chapter 1 introduces the concept of aquatic worm production on waste streams. Worm biomass composition and relevant research lines are explained. Organic waste sludges from food industries are a rich source of bio-molecules and can be upgraded to (fish) feed when fed to aquatic worms. For valorisation of waste streams by aquatic worms, as proposed in this thesis, these streams preferably are free from contaminants such as organic micro pollutants, heavy metals and pathogens. For example, this would not be the case when sewage (municipal) sludge is used as a substrate for the worms. However, such contaminated sludges may still be applied for non-food applications. Thus, the quality of the waste stream that is used as a substrate for the worms determines the application potential of the worm biomass as well as the options for downstream processing and refinery.

    Previous research showed that Lv can be used for reduction and compaction of sewage sludge. The consumption of (suspended) sludge particles results in a dry matter reduction of 25 - 50 % and in worm faeces that are 60 % more compact than the original waste sludge. This contributes to a significant reduction in sludge processing costs. Sludge reduction by aquatic worms is mainly studied by research groups in The Netherlands and in China. Unfortunately, it is generally accepted free swimming worms in full-scale wastewater treatment plants is extremely difficult, mainly because of large (seasonal) population fluctuations. A controlled reactor concept applying the sessile (crawling, sediment dwelling) species Lv already was developed in earlier research. The key characteristic of this reactor is a carrier material for the worms, which also functions as a separation layer between the waste stream (worm food) and a water phase used for aeration, worm harvesting and worm faeces collection. This concept also was the starting point for the development of the improved reactor concept that is described in this thesis.

    The two main objectives of this thesis were: (1) to assess the potential of organic waste streams and by-products for Lv production for fish feed and (2) to develop a (cost and resource) effective bioreactor for this purpose.

    In Chapter 2 a new, standardized method is described and tested that can be used for a quantitative and qualitative assessment of the effect of different substrates on worm growth. This method not only can be used to select waste streams suitable for worm production, but also is proposed as a tool is ecotoxicology studies.

    The test method consists of beaker experiments with a combination of agar and sand to optimize food uptake by and growth of the worms. The effects of agar gel, sand, and food quantity were studied and evaluated for different food sources. Agar gel addition ameliorated growth conditions by reducing microbial food hydrolysis and by improving the sediment structure. This guaranteed that substrate ingestion and worm growth in the first place were the result of the food quality and the effect of other (environmental) factors was reduced. A final test with secondary potato starch sludge demonstrated the test method is appropriate for the evaluation of solid and suspended organic feedstuffs/waste streams.

    In Chapter 3 the standardized method of chapter 2 was used for worm growth studies, focussing on the effect of carbon to nitrogen (C/N) ratios of diets on worm growth and reproduction. Growth and reproduction of Lv on different combinations of wheat based derivatives like gluten and gray starch was studied at fixed isoenergetic levels (expressed as chemical oxygen demand (COD) of the food), but at different C/N ratios. Growth and reproduction rates were compared to those on Tetramin, a substrate known to result in excellent worm growth. Growth was mainly controlled by the C/N ratio of the single and mixed wheat fraction diets. Lower C/N ratios of around 6-7 gave a much better performance than high C/N ratios of around 20. This probably was caused by Lv relying on the presence of proteins as carbon and energy source. Although growth and reproduction rates were not as high as on the control diet, the results were promising for development of a worm biomass production reactor, operating on by-products from wheat processing industries.

    In Chapter 4 a new reactor concept for Lv cultivation on waste streams was developed and tested. In a vertical tubular reactor a centralized food compartment was surrounded by a gravel layer that mimicked the natural habitat of Lv. Secondary (biological) sludge from a potato starch processing industry was used as a clean and low value food source. The results with respect to worm growth rate, density and production and nutrient recovery were compared to the previous reactor design. Much higher worm densities were achieved (6.0 compared to 1.1 kg ww m-2 carrier material) as well as much faster Lv growth rates (4.4 - 12 compared to 1.2 % d-1). As a result the areal worm production rate was no less than 40 times higher (560 compared to 14 g ww m-2 d-1). The higher worm density, which was found to be independent of gravel size in a range of 2.4 to 8.0 mm, allowed for a significantly shorter food retention time in the reactor (~ 2.2 days compared to > 10 days for the previous reactor design). This restricted microbial mineralization of the food, making high nutrient recoveries from waste to worm biomass possible: 16-30 % COD, 19-22 % N and 9-11 % P. The high biomass density also limited the release of ammonium, which at large concentrations is toxic for the worms. However, even shorter food retention times (e.g. higher loading rates) are not recommended as a minimum microbial activity is needed for conversion of the original substrate into compounds that can be taken up by the worms.

    In Chapter 5 worm growth, reproduction and biomass quality were evaluated on several waste streams and by-products of bacterial, animal and plant origin. The effect of 26 different diets, all applied at high food levels, on Lv growth, reproduction and fatty acid (FA) content and profile were investigated. For this purpose the standardized test method of Chapter 2 was used. In addition, it was discussed which diet composition and food sources would be most suitable for large scale production of Lv.

    Diets consisting of single cell biomass from bacterial or plant origin with a high protein content (C/N ratio < 8.8), high P content (C/P < 50) and low in total ammonia nitrogen (TAN) (< 20 g N/kg) gave the highest growth rates and vital worms without signs of mortality. Besides the C/P ratio of the diet, worm conditions related with the difference between test and pre-culture conditions. The starting weight of the worms seemed to have an effect on the total fatty acid content of the worms. The growth potential of a diet rich in proteins and P depends on how much TAN is associated with the diet. By blending different food sources these factors to a certain extent can be manipulated. Lv seemed to have a distinct and very stable FA composition, irrespective of the diet’s FA composition. The worms were rich in poly unsaturated FAs (PUFAs), including several w3 and w6 FAs, and contained relatively high levels of C18 and C20 PUFAs. This makes them suitable as fish feed, in particular for freshwater fish.

    In order to serve aquaculture feed markets with an attractive alternative to fish meal, such as aquatic worm biomass, a continuous and secure bulk production needs to be realized. In Chapter 6 the performance parameters established in chapter 4 (worm growth rate, density and biomass production rate) were used as the input for a feasibility assessment of large scale worm production on secondary sludge from the potato industry. In addition, in chapter 6 future value chains and lines of research were discussed.

    A hypothetical worm production system treating the surplus secondary sludge from a potato processing factory can reduce excess sludge production by 50 % in solids and 62 % in volume. This is accompanied by a daily production of 1.6 metric ton of fresh worm biomass. With a very conservative estimation of the worm density of 1.6 kg ww/m2 carrier material a footprint of the system of 217 m2 can be realized, which is at least two times smaller than with a previous reactor design without a gravel layer. With reduced sludge processing costs and a conservative market price of 1.4 €/kg dry worm biomass, worm production can already be realized at an annual rate of return of 3 years. However, the costs are highly sensitive for worm biomass stocking, reactor construction and operation. A more accurate economic assessment should be based on the results of pilot-scale research.

    Two general product types, whole biomass (as fish feed) and refined products can be distinguished and applied in two application areas (feed and non-food), depending on the quality of the organic (waste) sludge that the worms have been produced from. Valorisation for potential bulk markets needs further refinery of crude worm biomass into a lipid (worm oil) and a protein fraction (protein isolate). This can result in several new and unique business models in aquaculture, feed, chemical and agriculture sectors. Obviously, an assessment of economical and legislative boundary conditions needs to be part of such business models.

    Worm biomass is a potential high quality fishmeal replacer, with a similar or even better potential than other waste based alternatives such as single cell biomass and insects. A comparison between Lv and fishmeal with respect to crude composition, essential amino acids and FAs learns that Lv is a highly suitable fish feed source. It can provide essential amino acids at sufficiently high levels. Based on its FA composition and (relatively low) fat content, Lv can best be considered a protein source. Still, worm biomass is rich in PUFA, which could be a potential high value product for feed applications. Compared to black soldier fly and bacterial production systems, Lv shows intermediate production efficiencies, while biomass harvesting and processing probably is more easy.

    Additional advantages of Lv worm biomass to replace fishmeal are: 1) Lv acts as a strong natural fish attractant, 2) the growth efficiency of fish on worms is high in comparison to regular feeds, 3) the nutritional profile of worms matches that of fishmeal, 4) the worms are a natural feed source for freshwater fish and 5) the worms allow a secure and stable feed production that is independent of natural resources.

    Further recommendations for future research as outlined and discussed in chapter 6 are mostly related to the technical upscaling of the reactor technology and obtaining more detailed insight in controlled worm growth in response to food characteristics, reactor design and operational conditions.

    “Everything tastes different” : The impact of changes in chemosensory perception on food preferences, food intake and quality of life during chemotherapy in cancer patients
    Vries, Yfke Carlijn de - \ 2017
    Wageningen University. Promotor(en): Kees de Graaf; H.W.M. van Laarhoven, co-promotor(en): R.M. Winkels; Sanne Boesveldt. - Wageningen : Wageningen University - ISBN 9789463436090 - 169
    perception - sensory evaluation - food intake - quality of life - food preferences - neoplasms - taste - macronutrients - drug therapy - breast cancer - perceptie - sensorische evaluatie - voedselopname - kwaliteit van het leven - voedselvoorkeuren - neoplasma - smaak - macronutriënten - geneesmiddelenbehandeling - borstkanker

    Taste and smell changes are common side effects during chemotherapy in cancer patient and may have an impact on food preferences, food intake and quality of life. However, these relations have hardly been studied systematically in specific cancer populations. The overall aim of this thesis was to assess how the sense of taste and smell change upon treatment with chemotherapy in breast cancer and oesophagogastric cancer patients, and to investigate their consequences in terms of food preferences, food intake and quality of life.

    To measure food preferences for both macronutrients and tastes, the Macronutrient and Taste Preference Ranking Task (MTPRT) was developed. in chapter 2, it was shown that by inducing sensory specific satiety for a standardized sweet and savoury meal, it is possible to detect shifts in preferences for both tastes and macronutrients with the MTPRT, and that these results are reproducible.

    In Chapter 3 we studied objective and subjective taste and smell perception and food preferences in advanced oesophagogastric cancer patients undergoing palliative chemotherapy. The result showed that only objective taste function decreases during chemotherapy, but other chemosensory measures were unchanged. A lower subjective taste perception was related to a lower preference for high-protein products. Therefore it is important to consider patients’ taste perception, when providing dietary advice to OGC patients

    Chapter 4 describes a study with similar outcome measures as chapter 3, but in breast cancer patients at several time points during and after chemotherapy, and compared to a healthy control group. The study showed that breast cancer patients like high-protein, high-fat, sweet and savoury products less during chemotherapy, thus showing altered preferences for macronutrients, but not for tastes. Furthermore, results showed a temporary decrease in taste and smell perception during chemotherapy. These findings show that patients should be informed prior to treatment on chemosensory changes, and that these changes should be monitored during treatment due to the consequences for nutritional intake and quality of life

    In chapter 5 we assessed the dietary intake of breast cancer patients before and during chemotherapy compared to a healthy control group, and associations with experienced symptoms during chemotherapy. It was shown that symptoms induced by chemotherapy were associated with lower total energy, protein and fat intake, which was manifested by a lower intake of specific food groups. Therefore, to ensure an optimal dietary intake during chemotherapy, it is important to monitor nutritional status and symptom burden during chemotherapy in breast cancer patients.

    To better understand the impact of chemosensory changes during chemotherapy on daily life, 13 advanced oesophagogastric cancer patients were interviewed (see chapter 6). Patients described a substantial impact of chemosensory and food-related changes on daily life (by changing daily routines), social life (eating being less sociable) and roles in the household (changing roles in cooking and grocery shopping).

    Finally, in chapter 7, we assessed the association between self-reported taste and smell perception and quality of life in breast cancer patients. A worse taste and smell perception was associated with a worse global quality of life, role, social and emotional functioning shortly after chemotherapy. In patients treated with trastuzumab, a worse taste and smell perception was still associated with quality of life, social and role functioning half a year after chemotherapy had ended.

    From the studies in this thesis we can conclude that chemotherapy mainly affects the sense of taste. The subjective perception of taste was associated with a lower preference for food products and lower energy intake. This indicates that it is not necessarily an actual change in the sense of taste or smell that has an impact on patients, but flavour perception as a whole and potentially a lower enjoyment of food. Moreover, these perceived changes in taste and smell can have a substantial impact on cancer patients’ lives, in a practical way by changing daily patterns of eating, but also socially and in roles in the household. A changed chemosensory perception during chemotherapy may lead to a worsened nutritional status, and could thereby negatively impact the response to chemotherapy. Therefore chemosensory perception should be monitored during chemotherapy. Future studies should further investigate the mechanisms behind chemosensory changes, factors that contribute to subjective taste perception and possible interventions to alleviate chemosensory changes during chemotherapy.

    Transmissible mycobacterium tuberculosis strains share genetic markers and immune phenotypes
    Nebenzahl-Guimaraes, Hanna ; Laarhoven, Arjan van; Farhat, Maha R. ; Koeken, Valerie A.C.M. ; Mandemakers, Jornt J. ; Zomer, Aldert ; Hijum, Sacha A.F.T. Van; Netea, Mihai G. ; Murray, Megan ; Crevel, Reinout van; Soolingen, Dick van - \ 2017
    American Journal of Respiratory and Critical Care Medicine 195 (2017)11. - ISSN 1073-449X - p. 1519 - 1527.
    Bacterial genomes - Immunology - Transmission - Tuberculosis

    Rationale: Successful transmission of tuberculosis depends on the interplay of human behavior, host immune responses, and Mycobacterium tuberculosis virulence factors. Previous studies have been focused on identifying host risk factors associated with increased transmission, but the contribution of specific genetic variations in mycobacterial strains themselves are still unknown. Objectives: To identify mycobacterial genetic markers associated with increased transmissibility and to examine whether these markers lead to altered in vitro immune responses. Methods: Using a comprehensive tuberculosis registry (n = 10,389) and strain collection in the Netherlands, we identified a set of 100 M. tuberculosis strains either least or most likely to be transmitted after controlling for host factors.Wesubjected these strains to wholegenome sequencing and evolutionary convergence analysis, and we repeated this analysis in an independent validation cohort. We then performed immunological experiments to measure in vitro cytokine production and neutrophil responses to a subset of the original strains with or without the identified mutations associated with increased transmissibility. Measurements and Main Results: We identified the loci espE, PE-PGRS56, Rv0197, Rv2813-2814c, and Rv2815-2816c as targets of convergent evolution among transmissible strains. We validated four of these regions in an independent set of strains, and we demonstrated that mutations in these targets affected in vitro monocyte and T-cell cytokine production, neutrophil reactive oxygen species release, and apoptosis. Conclusions: In this study, we identified genetic markers in convergent evolution of M. tuberculosis toward enhanced transmissibility in vivo that are associated with altered immune responses in vitro.

    Weight change during chemotherapy in breast cancer patients : A meta-analysis
    Berg, M.M.G.A. van den; Winkels, R.M. ; Kruif, J.Th.C.M. ; Laarhoven, H.W.M. ; Visser, M. ; Vries, J.H.M. de; Vries, Y.C. de; Kampman, E. - \ 2017
    BMC Cancer 17 (2017)1. - ISSN 1471-2407
    Breast cancer - Chemotherapy - Meta-analysis - Weight change

    Background: Weight gain during chemotherapy in women with breast cancer is commonly reported. However, there are important differences between studies that examined weight change during chemotherapy; e.g. type of chemotherapy, menopausal status, time between body weight measurements and sample size. The purpose of this meta-analysis was to quantify changes in body weight during chemotherapy for women with breast cancer, taking these differences into account. Methods: We identified relevant studies using PubMed, Scopus and Embase databases. The search was limited to human studies published in English up to and including December 2015. Only studies among women with early stage breast cancer treated with chemotherapy, with reported body weight before and after chemotherapy and type of chemotherapy were included. Random-effect models were used, and heterogeneity between studies was explored through stratified analyses and meta-regression. Sensitivity analyses were done to explore whether a specific study markedly affected the results. Results: In total 25 papers were found, including data from 2620 women. Overall, body weight increased during chemotherapy: 2.7 kg (95% CI 2.0, 7.5) with a high degree of heterogeneity (I2 = 94.2%). Stratified analyses showed weight gain in all strata, but did not substantially reduce heterogeneity. Univariate meta-regression showed less weight gain in prospective studies compared to chart review studies (-2.0, 95% CI: -3.1, -0.8). Studies including cyclophosphamide, methotrexate and 5-fluorouracil (CMF) regimes showed a greater weight gain compared to those that did not (2.2, 95% CI: 1.1, 3.3); and papers published until the year 2000 showed a greater weight gain compared to those published after 2000 (1.9, 95% CI:-0.8, 3.1). In the multivariate models only studies including CMF regimes and studies published until 2000 were associated with significant weight gain of respectively 1.3 and 1.4 kg. Conclusion: Despite the high heterogeneity, this meta-analysis shows significant weight gain during chemotherapy for women with breast cancer. Weight gain was more pronounced in papers published until 2000 and women receiving CMF as chemotherapy regime. Although weight gain after chemotherapy has decreased over the course of time, weight gain is still substantial and deserves clinical attention.

    Differences in dietary intake during chemotherapy in breast cancer patients compared to women without cancer
    Vries, Y.C. de; Berg, M.M.G.A. van den; Vries, J.H.M. de; Boesveldt, S. ; Kruif, J.Th.C.M. de; Buist, N. ; Haringhuizen, A. ; Los, M. ; Sommeijer, D.W. ; Timmer-Bonte, J.H.N. ; Laarhoven, H.W.M. van; Visser, M. ; Kampman, E. ; Winkels, R.M. - \ 2017
    Supportive Care in Cancer 25 (2017)8. - ISSN 0941-4355 - p. 2581 - 2591.
    Purpose: Breast cancer patients receiving chemotherapy often experience symptoms such as nausea, vomiting and loss of appetite that potentially affect dietary habits. This study assessed the intake of energy, macronutrients and food groups before and during chemotherapy in breast cancer patients compared with women without cancer, and determined the association between symptoms and energy and macronutrient intake.
    Methods: This study included 117 newly diagnosed breast cancer patients scheduled for chemotherapy and 88 women without cancer. Habitual intake before chemotherapy was assessed with a food frequency questionnaire. Two 24-h dietary recalls were completed on random days for each participant during the whole chemotherapy treatment for patients and within 6 months after recruitment for women without cancer. Shortly, after the dietary recall, participants filled out questionnaires on symptoms.
    Results: Before chemotherapy, habitual energy and macronutrient intake was similar for breast cancer patients and women without cancer. During chemotherapy, breast cancer patients reported a significantly lower total energy, fat, protein and alcohol intake than women without cancer, as shown by a lower intake of pastry and biscuits, cheese, legumes and meat products. A decline in subjective taste perception, appetite and hunger and experiencing a dry mouth, difficulty chewing, lack of energy and nausea were associated with a lower energy intake.
    Conclusions: Symptoms induced by chemotherapy are associated with lower dietary intake and manifested by a lower intake of specific food groups. To ensure an optimal dietary intake during chemotherapy, it is important to monitor nutritional status and symptom burden during chemotherapy in breast cancer patients.
    Impact of compost and manure on the ripening of dredged sediments
    Figueiredo Oliveira, Bruna Raquel ; Laarhoven, Bob ; Smit, Martijn P.J. ; Rijnaarts, Huub H.M. ; Grotenhuis, Tim - \ 2017
    Journal of Soils and Sediments 17 (2017)2. - ISSN 1439-0108 - p. 567 - 577.
    Beneficial use - Compost - Dredged sediments - Priming effect - Ripening - Rock-Eval - Swine manure - Undrained shear strength

    Purpose: In low lying areas with dense networks of canals for land drainage, sediments accumulate in the waterways and have to be periodically dredged. These adjacent areas are mainly used for farming and agriculture and suffer from high rates of subsidence. The recycling of organic amendments, such as sediments, compost and manure, in agricultural soils can improve plant growth and yield, soil carbon content, and microbial biomass and activity, and have the potential to reverse the process of land subsidence. Materials and methods: The effect of mixing bio-waste compost and the solid fraction of swine manure with dredged sediments before dewatering and biochemical ripening was investigated in terms of type and quantity of organic matter, CO2 production and O2 consumption, and N, P and S content. The water released during dewatering, the aggregate stability, and the undrained shear strength after ripening were also assessed since these areas have to be assessable by trucks and cattle. Results and discussion: For the sediment with compost and manure the transformations in the type of organic matter, CO2 production and O2 consumption were larger compared to the individual fractions, indicating a positive priming effect. Most volume lost during ripening can be attributed to the loss of water and not to the loss of organic matter. In addition, the mixtures result in very stable aggregates and showed an undrained shear strength three times higher than measured for the sediments. Conclusions: Sediments, compost and manure can be used and applied as beneficial use to reverse the process of land subsidence in low lying areas.

    Glutaminolysis and Fumarate Accumulation Integrate Immunometabolic and Epigenetic Programs in Trained Immunity
    Arts, Rob J.W. ; Novakovic, Boris ; Horst, Rob ter; Carvalho, Agostinho ; Bekkering, Siroon ; Lachmandas, Ekta ; Rodrigues, Fernando ; Silvestre, Ricardo ; Cheng, Shih Chin ; Wang, Shuang Yin ; Habibi, Ehsan ; Gonçalves, Luís G. ; Mesquita, Inês ; Cunha, Cristina ; Laarhoven, Arjan van; Veerdonk, Frank L. van de; Williams, David L. ; Meer, Jos W.M. van der; Logie, Colin ; O'Neill, Luke A. ; Dinarello, Charles A. ; Riksen, Niels P. ; Crevel, Reinout van; Clish, Clary ; Notebaart, Richard A. ; Joosten, Leo A.B. ; Stunnenberg, Hendrik G. ; Xavier, Ramnik J. ; Netea, Mihai G. - \ 2016
    Cell Metabolism 24 (2016)6. - ISSN 1550-4131 - p. 807 - 819.
    cholesterol metabolism - epigenetics - glutamine metabolism - glycolysis - trained immunity

    Induction of trained immunity (innate immune memory) is mediated by activation of immune and metabolic pathways that result in epigenetic rewiring of cellular functional programs. Through network-level integration of transcriptomics and metabolomics data, we identify glycolysis, glutaminolysis, and the cholesterol synthesis pathway as indispensable for the induction of trained immunity by β-glucan in monocytes. Accumulation of fumarate, due to glutamine replenishment of the TCA cycle, integrates immune and metabolic circuits to induce monocyte epigenetic reprogramming by inhibiting KDM5 histone demethylases. Furthermore, fumarate itself induced an epigenetic program similar to β-glucan-induced trained immunity. In line with this, inhibition of glutaminolysis and cholesterol synthesis in mice reduced the induction of trained immunity by β-glucan. Identification of the metabolic pathways leading to induction of trained immunity contributes to our understanding of innate immune memory and opens new therapeutic avenues.

    The carbon to nitrogen ratio in isoenergetic wheat based diets controls the growth rate of the aquatic worm Lumbriculus variegatus
    Laarhoven, B. ; Elissen, H.J.H. ; Buisman, C.J.N. ; Temmink, H. - \ 2016
    Journal of Insects as Food and Feed 2 (2016)4. - ISSN 2352-4588 - p. 225 - 231.
    The aquatic worm Lumbriculus variegatus (Lv) contains high levels of proteins and can provide an excellent fish food. Large-scale production of Lv on low value organic substrates, such as by-products produced during wheat processing, therefore can be a promising and sustainable concept for the aquaculture industry. Growth and reproduction of Lv on different combinations of wheat based derivatives was studied at fixed isoenergetic levels (expressed by the chemical oxygen demand of the food), but at different carbon to nitrogen (C:N) mass ratios under controlled conditions in specifically designed test-beaker tests. Growth and reproduction rates were compared to those on Tetramin®, a substrate known to give excellent growth of Lv. Although Lv did exhibit a growth response on single as well as on mixed wheat fractions, growth was mainly controlled by the C:N ratio of the diets. Lower C:N ratios of typically 6-7 gave a much better performance than high C:N ratios of approximately 20. It was discussed this is probably caused by Lv relying on the presence of proteins for their carbon and energy source. Although growth and reproduction rates were not as high as on the control diet, the results are promising for the development of a worm biomass production system operating on by-products from the wheat processing industry
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