{"id":11312,"date":"2026-04-13T09:22:22","date_gmt":"2026-04-13T09:22:22","guid":{"rendered":"https:\/\/www.proefschriftmaken.nl\/portfolio\/umi-kalsum-zaki\/"},"modified":"2026-04-22T14:49:48","modified_gmt":"2026-04-22T14:49:48","slug":"umi-kalsum-zaki","status":"publish","type":"us_portfolio","link":"https:\/\/www.proefschriftmaken.nl\/en\/portfolio\/umi-kalsum-zaki\/","title":{"rendered":"Umi Kalsum Zaki"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"","protected":false},"author":8,"featured_media":12184,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"us_portfolio_category":[45],"class_list":["post-11312","us_portfolio","type-us_portfolio","status-publish","has-post-thumbnail","hentry","us_portfolio_category-new-template"],"acf":{"naam_van_het_proefschift":"Lignan intake & obesity","samenvatting":"Er is geen Nederlandse samenvatting beschikbaar. De Engelse samenvatting vind je <a href=\"https:\/\/www.proefschriftmaken.nl\/en\/portfolio\/umi-kalsum-zaki\/\">hier<\/a>.","summary":"Obesity represents one of the most significant health and socioeconomic burdens to modern society. Lignan foods are commonly consumed in diets worldwide and can be an important part of an effective strategy to help prevent and manage obesity. However, precise associations between the consumption of lignan foods and obesity have not been reported extensively. Furthermore, the insight in the impact of different processing methods on bioaccessibility and conversion to gut microbial metabolites that are more bioactive is lacking. Therefore, this thesis aimed to look at the definition of phytoestrogens, particularly lignans, the lignan content of various foods, their bioaccessibility, and conversion into microbial metabolites in the human large intestine. Further, we assessed the lignans food intake in relation to obesity indicators in a Dutch population.\n\nFirstly, to capture the existing phytoestrogen compounds in regard to obesity, a systematic review was conducted, and the result is presented in Chapter 2. The lignans and isoflavones studied showed significant weight loss effects in both human and animal studies. As a result, lignans were chosen for further investigation since the review revealed that they have a more significant potential influence on weight loss than isoflavones.\n\nIn Chapter 3, the influence of different bioprocessing techniques on lignan content was further evaluated. The plant-based foods were selected based on data from The National Health Morbidity Survey, Malaysia Adult Nutrition Survey (MANS) conducted in 2014: shallot, celery, green Chinese mustard, long bean, mung beans, soybeans, flaxseed and tea. Pickling significantly reduced the content of lariciresinol by approximately 86%. Conversely, fermentation and germination increased lignan content. Moreover, the lignan content increased with prolonged brewing in tea. Thus, fermentation, germination, as well as prolonged brewing of tea have shown to be potential techniques to improve the lignan content in foods.\n\nThe analysis of the lignan foods was further expanded in Chapter 4, where the effect of bioprocessing on bioaccessibility and gut microbiota conversion in enterolignans using flaxseed were studied. In addition, tea brew was used as a representative sample to investigate lignan stability and interactions with digestive fluids. The bioaccessibility of lignans was very low (1% or less), and lignans are unstable in simulated in-vitro digestion conditions in all fresh, germinated, and flaxseed for both fine and coarse particle sizes. The particle size and processing significantly affected the secoisolariciresinol (SECO) bioaccessibility. Fermentation, on the other hand, could be a viable strategy for increasing lignan release and conversion to enterolactone (EL) in the large intestine. Moreover, the inter-individual microbiota influenced the conversion of lignans to EL.\n\nFinally, in Chapter 5, the lignan intake association with obesity indicators (body mass index and waist circumference) were evaluated in a Dutch adult population using a real-life prospective cohort study, \u201cNutritional Questionnaire plus\u201d (NQplus). Bread was the most common source of lignans, followed by nuts, seeds, snacks, and vegetables. A higher lignan intake was associated with a smaller waist circumference also when adjusted for potential confounders. Whether lignans can reduce waist circumference in obese people or prevent the onset of abdominal obesity must be evaluated in future intervention studies.\n\nCollectively, the findings from these chapters indicate the potential for further exploring the lignan content in foods, and processing techniques to increase the bioaccessibility and conversion of lignans to enterolignans. The current research could aid in the development of low-cost and time-saving food with manifold healthy properties.","auteur":"Umi Kalsum Zaki","auteur_slug":"umi-kalsum-zaki","publicatiedatum":"8 november 2022","taal":"EN","url_flipbook":"https:\/\/ebook.proefschriftmaken.nl\/ebook\/umikalsumzaki?iframe=true","url_download_pdf":"","url_epub":"","ordernummer":"FTP-202604130920","isbn":"978-94-6447-336-0","doi_nummer":"","naam_universiteit":"Wageningen University","afbeeldingen":12184,"naam_student:":"","binnenwerk":"","universiteit":"Wageningen University","cover":"","afwerking":"","cover_afwerking":"","design":""},"_links":{"self":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio\/11312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio"}],"about":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/types\/us_portfolio"}],"author":[{"embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/comments?post=11312"}],"version-history":[{"count":1,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio\/11312\/revisions"}],"predecessor-version":[{"id":11313,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio\/11312\/revisions\/11313"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/media\/12184"}],"wp:attachment":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/media?parent=11312"}],"wp:term":[{"taxonomy":"us_portfolio_category","embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio_category?post=11312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}