THE EFFECTS OF FORMULATION AND DOSING FREQUENCY OF PLANT STEROLS ON PLASMA LIPID PROFILES AND CHOLESTEROL KINETICS PARAMETERS IN HYPERCHOLESTEROLEMIC SUBJECTS Suhad Sameer AbuMweis School of Dietetics and Human Nutrition McGill University, Montreal August 2007 A thesis submitted to McGill University in partial fulfillment of the requirements of the degree of Doctor of Philosophy © Suhad S AbuMweis 2007 Library and Bibliotheque et 1*1 Archives Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-50761-2 Our file Notre reference ISBN: 978-0-494-50761-2 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library permettant a la Bibliotheque et Archives and Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par Plntemet, prefer, telecommunication or on the Internet, distribuer et vendre des theses partout dans loan, distribute and sell theses le monde, a des fins commerciales ou autres, worldwide, for commercial or non­ sur support microforme, papier, electronique commercial purposes, in microform, et/ou autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in et des droits moraux qui protege cette these. this thesis. Neither the thesis Ni la these ni des extraits substantiels de nor substantial extracts from it celle-ci ne doivent etre imprimes ou autrement may be printed or otherwise reproduits sans son autorisation. reproduced without the author's permission. In compliance with the Canadian Conformement a la loi canadienne Privacy Act some supporting sur la protection de la vie privee, forms may have been removed quelques formulaires secondaires from this thesis. ont ete enleves de cette these. While these forms may be included Bien que ces formulaires in the document page count, aient inclus dans la pagination, their removal does not represent il n'y aura aucun contenu manquant. any loss of content from the thesis. Canada ABSTRACT Plant sterol-containing food products are known to reduce low density lipoprotein (LDL) cholesterol, with the degree of placebo-adjusted reduction ranging from 5% to 15%. Factors that affect plant sterol efficacy such as the type of formulation and dosing frequency are still to be determined. Thus, the objective of this thesis was to investigate the impact of novel plant sterol preparations, frequency of intake and time of intake of plant sterols on cholesterol kinetics and/or plasma lipid profile. Three randomized, placebo-controlled, single-blind, crossover, supervised feeding trials were conducted in 75 subjects with LDL levels of > 3.0 mmol/L. The results from the 3 studies showed that: (i) traditional forms of plant sterols did not reduce LDL levels when given as a single morning dose, thus the efficacy of the novel formulation of plant sterols could not be confirmed; (ii) consumption of 1.8 g/d of plant sterols equally distributed over the day lowered LDL, whereas the consumption of the same dose once a day with breakfast did not lower LDL levels, in spite of a reduction in cholesterol absorption efficiency; (iii) cholesterol fractional synthesis rate (FSR) increased when plant sterols were consumed 3 times/d, but not as a single morning dose, which could be attributed to feedback up- regulation of cholesterol FSR inresponse to reduced cholesterol absorption; and (iv) no overall reduction in LDL levels were observed when a 1.6 g/d of single dose of plant sterols provided in yoghurt was consumed with breakfast or dinner; however, a reduction in LDL was observed in subjects with low baseline cholesterol absorption efficiency irrespective of time of intake. Furthermore, we performed a meta-analysis to further identify any factors that could affect the efficacy of plant sterols and the results demonstrated that: (i) consumption of plant sterols reduce LDL levels by 0.31 mmol/L; Ill (ii) the reduction in LDL was greater in studies conducted on individuals with high baseline LDL levels; (iii) plant sterols incorporated into margarine, mayonnaise and salad dressing, milk and yogurt reduced LDL levels to greater extent than plant sterols incorporated into other food products; and (iv) plant sterols consumed as single dose in the morning did not reduce plasma LDL levels. In conclusion, the consumption of single morning dose of plant sterols may not be effective in reducing LDL levels, and that margarine, mayonnaise and salad dressing, milk and yoghurt are the best food carrier of plant sterols. In addition, subjects' baseline LDL levels and cholesterol absorption efficiency influence the response to plant sterols. Therefore, these findings could be used to improve plant sterol efficacy, as well as to establish future health claims. IV RESUME Les produits alimentaires contenant des sterols vegetaux sont des aliments fonctionnels connus pour leur effet reducteur sur le cholesterol LDL variant entre 5% et 15% par rapport au placebo. Cependant, les facteurs affectant l'efficacite des sterols des plantes, notamment le type de formulation et la frequence de dosage n'ont pas encore ete determines. L'objectif de la presente these est done d'etudier l'impact de nouvelles preparations de sterols vegetaux, ainsi que la frequence et le moment du dosage, sur la cinetique du cholesterol et/ou le profile lipidique du plasma. Trois etudes alimentaires, croisees en simple aveugle, controlees contre placebo ont ete effectuees incluant un echantillon de 75 hommes et femmes post-menopausees ayant des taux de cholesterol LDL > 3 mmol/1. Les resultats des trois etudes demontrent que (i) les formes traditionnelles de sterols vegetaux ne reduisent pas les taux de cholesterol sanguin lorsqu'elles sont administrees en une dose matinale, l'efficacite des nouvelles preparations de sterols vegetaux ne peuvent done pas etre confirmees (ii) une dose de 1.8 g/jour de sterols vegetaux distribute en doses egales pendant lajournee reduit le taux de cholesterol LDL, contrairement a la meme dose consommee avec le petit-dejeuner malgre 1'effet reducteur de cette derniere sur l'absorption intestinale du cholesterol, (iii) la vitesse de synthese fractionnelle du cholesterol a tendance a augmenter lorsque les sterols vegetaux sont consommes avec chacun des trois repas, mais pas en une seule dose matinale, ce qui pourrait etre attribue a une regulation positive de la synthese du cholesterol par retroaction negative en reponse a une absorption de sterols limitee et (iv) aucune reduction des taux de cholesterol LDL n'a ete observee en reponse a une seule dose de 1.6 g/jour de sterols vegetaux, incorporee dans du yaourt et consommee avec le V petit-dejeuner ou le souper; cependant, une reduction du taux de cholesterol LDL a ete observee chez les sujets ayant une basse absorption intestinale de cholesterol de base, et cela independamment du moment d'administration du traitement. De plus, nous avons effectue une meta analyse afin de determiner les facteurs affectant Pefficacite des sterols vegetaux. Les resultats demontrent que: (i) la consommation des sterols/stanols vegetaux reduit les taux de cholesterol LDL de 0.31 mmol/1, (ii) de plus importants effets sont observes dans les etudes incluant des sujets ayant des taux de base plus el eves, (iii) les sterols vegetaux produisent des reductions du taux de cholesterol LDL plus importantes lorsqu'ils sont incorpores dans la margarine, la mayonnaise, la vinaigrette, le lait et le yaourt que dans le cas d'autres produits alimentaires et (iv) une seule dose matinale de sterols vegetaux ne reduit pas le taux de cholesterol LDL du plasma. En conclusion, nos resultats suggerent qu'une seule dose matinale de sterols vegetaux ne reduirait pas le taux de cholesterol LDL sanguin, et que les aliments gras comme la margarine et la mayonnaise, ainsi que le lait et le yaourt sont les vehicules les plus efficaces pour les sterols vegetaux. De plus, les taux de base de cholesterol LDL ainsi que Pefficacite de base de 1'absorption intestinale du cholesterol ont un effet significatif sur la reponse aux sterols vegetaux. Ces resultats pourraient done etre utilises pour ameliorer Pefficacite des sterols vegetaux ainsi que pour etablir des allegations de sante. VI ADVANCE OF SCHOLARLY KNOWLEDGE 1. Original contribution to knowledge The following are the contributions of this thesis to knowledge in the field of plant sterols and cholesterol metabolism: - Examines for the first time the question of potential efficacy of novel plant sterol preparations, i.e. plant sterols + fish oil fatty acids and plant sterols-fish oil fatty acid ester, on plasma lipid profile and shows that a single morning dose of traditional and novel forms does not dramatically affect LDL-cholesterol levels. Demonstrates the efficacy of plant sterols as cholesterol-lowering agents during a very short-term period of consumption. - Shows that dosing frequency is a critical factor in the cholesterol- lowering potential of plant sterols. Plant sterols consumed with breakfast, lunch and dinner was more efficacious than plant sterols as a single morning dose in decreasing LDL-cholesterol levels, relative to control. This effect appeared to be attributable to feedback