Le but de cette étude consiste à démontrer l’impact positif d’une supplémentation en glutamine chez des nageurs élites, afin d’améliorer le statut immunitaire et d’évaluer si les changements plasmatiques de la glutamine peuvent expliquer l’incidence d’infections des voies respiratoires (IVRS). En parallèle, ce projet évalue si les apports alimentaires influencent la glutamine plasmatique et l’incidence d’IVRS. L’étude s’est effectuée auprès de 14 athlètes élites (8 hommes, 6 femmes). Chaque athlète a participé aux deux conditions expérimentales : un supplément de glutamine et une solution placebo isocalorique. Les périodes de supplémentation se déroulaient sur sept jours, incluant trois journées consécutives de compétition. Le profil hématologique, après les compétitions, montre qu’un supplément de glutamine n’améliore pas significativement la concentration plasmatique en glutamine ni les niveaux de cytokines comparativement à une solution placebo. Bien que les résultats soient semblables sous les deux conditions, les niveaux post-compétition ont tendance à être supérieurs aux valeurs pré-supplémentation, lorsqu’un apport exogène en glutamine est fourni à l’organisme alors que les concentrations plasmatiques de glutamine tendent à diminuer lorsqu’une solution placebo est administrée (p=0.067). L'incidence d’IVRS ne peut être expliquée par une faible concentration plasmatique de glutamine ni par un apport exogène de glutamine. On observe cependant une augmentation d’IVRS suite aux compétitions, soient de 8 athlètes pour le groupe placebo contre 3 au groupe glutamine. Les athlètes atteints d'IVRS semblent consommer moins d'énergie totale (kcal) et de protéines que les athlètes sains (p=0.060). Les résultats obtenus ne démontrent pas qu’une supplémentation en glutamine améliore le profil immunitaire et ne prévienne l’incidence d’IVRS, mais ils soulèvent l’hypothèse qu’un apport exogène en glutamine stabilise les niveaux plasmatiques de glutamine, permettant aux athlètes de poursuivre leurs entraînements et de récupérer efficacement. / The purposes of this study were to determine the positive impacts of glutamine supplementation upon immune system status and to determine whether changes in plasma glutamine relate to the appearance of upper respiratory tract infections (URTI) in elite swimmers. Furthermore, this study evaluated dietary intakes and its influence on immune parameters and URTI incidence. Fourteen athletes (8 men, 6 women) took part of the study. Each athlete participated in both experimental conditions: glutamine supplement and an isocaloric solution placebo. The supplementation period lasted seven day, including three consecutive competing days. Post competing hematologic profils of swimmers show that glutamine supplement does not significantly improve plasma glutamine neither cytokines levels, compared to a placebo solution. Even if plasma glutamine concentrations are similar with both conditions, the post competiting levels tend to be higher than pre competing values, when glutamine is supplemented. Futhermore, plasma glutamine levels show a decreasing trend under control conditions (p=0.060). In this study, URTI can not be explained by low plasma glutamine or supplemented glutamine. However, URTI incidence is higher after competitions, where 8 athletes showed symptoms (control group) and 3 only in the experimental group. Athletes with URTI seem to consume less energy and proteins than healthy athletes (p=0.060). These data does not suggest that glutamine supplementation improves immune function or prevents URTI in highly trained swimmers during competition. However, results support the hypothesis that exogenous glutamine stabilizes plasma glutamine levels, allowing athletes to tolerate training workload and recover properly.

La vitamine K fait l’objet d’un intérêt croissant en regard du rôle qu’elle peut jouer dans la santé humaine hormis celui bien établi dans la coagulation sanguine. De plus en plus d’études expérimentales lui confèrent des fonctions dans le système nerveux central, particulièrement dans la synthèse des sphingolipides, l’activation de la protéine vitamine K-dépendante Gas6 et la protection contre les dommages oxydatifs. Toutefois, il demeure beaucoup moins bien établi si la perturbation de ces fonctions peut conduire à des déficits cognitifs. L’objectif principal de cette thèse est de vérifier l’hypothèse selon laquelle le statut vitaminique K des personnes âgées en santé est un déterminant de la performance cognitive. En vue de la réalisation de cet objectif, une meilleure compréhension des indicateurs du statut vitaminique K s’avérait nécessaire. Chacune des études présentées vise donc un objectif spécifique : 1) évaluer le nombre de rappels alimentaires de 24 heures non consécutifs nécessaire pour mesurer l’apport habituel de vitamine K des personnes âgées; 2) évaluer la valeur d’une seule mesure de la concentration sérique de vitamine K comme marqueur de l’exposition à long terme; et 3) examiner l’association entre le statut vitaminique K et la performance cognitive des personnes âgées en santé de la cohorte québécoise NuAge. Trois dimensions cognitives ont été évaluées soient la mémoire épisodique verbale et non-verbale, les fonctions exécutives et la vitesse de traitement de l’information. Cette thèse présente la première étude appuyant l’hypothèse d’un rôle de la vitamine K dans la cognition chez les personnes âgées. Spécifiquement, la concentration sérique de vitamine K a été associée positivement à la performance en mémoire épisodique verbale, et plus particulièrement au processus de consolidation de la trace mnésique. En accord avec les travaux chez l’animal et l’action de la protéine Gas6 dans l’hippocampe, un rôle spécifique de la vitamine K à l’étape de consolidation est biologiquement plausible. Aucune association significative n’a été observée avec les fonctions exécutives et la vitesse de traitement de l’information. Parallèlement, il a été démontré qu’une mesure unique de la concentration sérique de vitamine K constitue une mesure adéquate de l’exposition à long terme à la vitamine K. De même, il a été établi que six à 13 rappels alimentaires de 24 heures sont nécessaires pour estimer précisément l’apport de vitamine K des personnes âgées en santé. Collectivement, les résultats de ces deux études fournissent des informations précieuses aux chercheurs permettant une meilleure interprétation des études existantes et une meilleure planification des études futures. Les résultats de cette thèse constituent une avancée importante dans la compréhension du rôle potentiel de la vitamine K dans le système nerveux central et renforce la nécessité qu’elle soit considérée en tant que facteur nutritionnel du vieillissement cognitif, en particulier chez les personnes traitées par un antagoniste de la vitamine K. / There is an increasing interest in the potential roles of vitamin K in human health aside from the one well established in blood clotting. Notably, a growing number of experimental studies show that vitamin K has biological functions in the central nervous system, particularly in the synthesis of sphingolipids, the activation of the vitamin K-dependent protein Gas6, and the prevention of oxidative damage. However, it remains uncertain whether the disruption of these functions can lead to cognitive deficits. The main objective of this thesis is to test the hypothesis that vitamin K status is a determinant of cognitive performance in healthy older adults. In order to achieve this goal, a better understanding of vitamin K status indicators was needed. Accordingly, three studies are presented each aiming at a specific objective: 1) estimate the number of non-consecutive 24-hour dietary recalls needed to assess usual vitamin K intake; 2) determine whether a single measurement of serum vitamin K concentration is an adequate indicator of long-term vitamin K exposure; and 3) examine the association between vitamin K status and cognitive performance in healthy older adults from the Québec NuAge Study. Three cognitive domains were assessed namely verbal and non-verbal episodic memory, executive functions, and speed of processing. This thesis presents the first study providing support for a role of vitamin K in cognition in older adults. Specifically, serum vitamin K concentration was positively associated with performance in verbal episodic memory, particularly in the consolidation process of the memory trace. Consistent with rodent studies and the action of the protein Gas6 in the hippocampus, a specific role of vitamin K in memory consolidation is biologically plausible. No significant association was observed with executive functions and speed of processing. Additionally, it was established that a single measurement of serum vitamin K concentration is adequate for assessing long-term vitamin K exposure in healthy older adults. Similarly, it was determined that six to 13 24-hour dietary recalls are needed to accurately assess usual vitamin K intake. Collectively, both studies provide valuable information to researchers for better interpretation of existing studies and planning future ones. Results from this thesis constitute an important step in the understanding of the potential role of vitamin K in the central nervous system, emphasizing the need to consider this micronutrient as a nutritional factor of cognitive aging, especially among those treated with vitamin K antagonists.

Introdução: A alimentação é um dos fatores determinantes da saúde. Estudantes de Nutrição, quando formados, atuarão com base em sua percepção de alimentação saudável para promover, manter e recuperar a saúde por meio da alimentação. Por isso, sua percepção de alimentação saudável, que é variável e influenciada por múltiplos fatores, pode impactar a saúde e o atual cenário epidemiológico. Objetivo: explorar a percepção de alimentação saudável de estudantes de Nutrição do estado de São Paulo. Materiais e métodos: uma amostra de 625 estudantes de graduação em Nutrição de 42 instituições públicas e privadas localizadas em 25 municípios do estado de São Paulo, participantes do Estudo de Saúde dos Nutricionistas respondeu, de forma online, um questionário com abordagem quantitativa e qualitativa desenvolvido para avaliar a percepção de alimentação saudável, a Escala de Silhuetas Brasileiras, a subescala Relação com a comida da Escala de Atitudes Alimentares Transtornadas, um questionário para avaliar comportamento de risco para transtornos alimentares (TA), além de questões de caracterização da amostra. Foram investigadas a associação entre a percepção de alimentação saudável e tipo de instituição, fase da graduação, sexo, estado nutricional, comportamento de risco para TA, satisfação corporal por meio do teste qui-quadrado; a relação entre a percepção de alimentação saudável e relacionamento com a comida por meio do teste de Mann Whitney; e a predição da percepção de alimentação saudável a partir das variáveis do estudo por meio de um modelo de Árvore de Classificação e Regressão. Resultados: Dos estudantes, 82,4% eram provenientes de instituições privadas, tinham em média 23,42 anos (DP=2,96), 93,4% eram do sexo feminino, 70,2% era eutrófica, 23,2% relataram algum comportamento de risco para TA, 85,0% estavam insatisfeitos com sua imagem corporal, 71,5% entendiam alimentação saudável exclusivamente do ponto de vista biológico e 28,5% consideravam alimentação saudável como um fenômeno biopsicossociocultural. A percepção de alimentação saudável esteve associada ao tipo de instituição de ensino e fase da graduação, sendo que estudantes de instituições públicas e no final da graduação, entendiam, em maior frequência, alimentação saudável como aquela que considera aspectos biopsicossocioculturais (p<0,001, para ambos). Não foram encontradas associações entre percepção de alimentação saudável e sexo (p=0,910), estado nutricional (p=0,552), comportamento de risco para TA (0,382) e satisfação corporal (p=0,352), nem relação entre percepção de alimentação saudável e relacionamento com a comida (p=0,159). A percepção de alimentação saudável pôde ser predita, com precisão de 66,4%, principalmente a partir do tipo de instituição, da percepção da função do nutricionista, do semestre da graduação, do nível de atividade física, do uso de artigos científicos como fonte de informação, da percepção corporal e da atitude com relação à manteiga, sendo o tipo de instituição de ensino o fator mais importante para classificar os estudantes segundo a percepção biológica e biopsicossociocultural da alimentação. Conclusão: A maior parte dos estudantes entende que a percepção de alimentação saudável está relacionada, principalmente, aos aspectos biológicos. Enquanto que uma parcela menor entende a alimentação saudável como um fenômeno biopsicossociocultural. A percepção de alimentação saudável esteve associada ao tipo de instituição de ensino e fase da graduação e não esteve associada a sexo, estado nutricional, comportamento de risco para TA, satisfação corporal e relacionamento com a comida. O estudo oferece como contribuição uma ferramenta para predição da percepção de alimentação saudável dos estudantes e uma reflexão sobre a formação do nutricionista, servindo de base para a proposição de estratégias de ensino que promovam a visão biopsicossociocultural da alimentação, saúde e Nutrição. / Introduction: Food is one of the determinants of health. Students of Nutrition, when graduated, will act based on their perception of healthy eating to promote, maintain and restore health through foods. Therefore, their perception of healthy eating, which is variable and influenced by multiple factors, can impact health and the current epidemiological scenario. Objective: to explore the perception of healthy eating among students of Nutrition in the state of São Paulo - Brazil. Materials and methods: a sample of 625 undergraduate students of Nutrition from 42 public and private institutions located in 25 municipalities of the state of São Paulo, participants of the Health Study of Nutritionists, answered online, a questionnaire with quantitative and qualitative approach developed to evaluate the perception of healthy eating, the Figure Rating Scales for Brazilian Adults, the subscale Relation with food of the Disordered Eating Attitude Scale, a questionnaire to evaluate risk for eating disorders (ED), and questions of characterization of the sample. We investigated the association between the perception of healthy eating and type of institution, graduation phase, sex, nutritional status, risk for ED, body satisfaction through the chi-square test; the relation between the perception of healthy eating and relationship with food through the Mann Whitney test; and the prediction of healthy eating perception from the study variables through a Classification and Regression Tree model. Results: Of the students, 82.4% came from private institutions, had a mean of 23.42 years (SD = 2.96), 93.4% were female, 70.2% had normal weight, 23, 2% reported some risk behavior for ED, 85% were dissatisfied with their body image, 71.5% considered healthy eating exclusively from a biological point of view and 28.5% considered healthy eating as a biopsychosociocultural phenomenon. The perception of healthy eating was associated with the type of institution and undergraduate phase, and students from public institutions and at the end of the undergraduate course understood, more frequently, healthy eating as the one that considers biopsychosociocultural aspects (p < 0.001, for both). There were no associations between healthy eating perception and sex (p = 0.910), nutritional status (p = 0.552), risk behavior for ED (p = 0.382) and body satisfaction (p = 0.352), nor relation between healthy eating perception and relationship with food (p = 0.159). The perception of healthy eating could be predicted with an accuracy of 66.4%, mainly from the type of institution, the perception of the function of the dietitian, the graduation semester, the level of physical activity, the use of scientific articles as a source of information, body perception and attitude towards butter, and the type of institution is the most important factor to classify students according to the biological and biopsychosociocultural perception of healthy eating. Conclusion: Most students understand that the perception of healthy eating is mainly related to biological aspects. While a smaller portion understands healthy eating as a biopsychosociocultural phenomenon. The perception of healthy eating was associated with the type of institution and graduation phase and was not associated with gender, nutritional status, risk for ED, body satisfaction and relationship with food. The study offers as a contribution a tool to predict the perception of healthy eating of students and a reflection on the formation of the dietitian, serving as the basis for proposing teaching strategies that promote the biopsychosociocultural view of food, health and Nutrition.

Introdução: A alimentação é um dos fatores determinantes da saúde. Estudantes de Nutrição, quando formados, atuarão com base em sua percepção de alimentação saudável para promover, manter e recuperar a saúde por meio da alimentação. Por isso, sua percepção de alimentação saudável, que é variável e influenciada por múltiplos fatores, pode impactar a saúde e o atual cenário epidemiológico. Objetivo: explorar a percepção de alimentação saudável de estudantes de Nutrição do estado de São Paulo. Materiais e métodos: uma amostra de 625 estudantes de graduação em Nutrição de 42 instituições públicas e privadas localizadas em 25 municípios do estado de São Paulo, participantes do Estudo de Saúde dos Nutricionistas respondeu, de forma online, um questionário com abordagem quantitativa e qualitativa desenvolvido para avaliar a percepção de alimentação saudável, a Escala de Silhuetas Brasileiras, a subescala Relação com a comida da Escala de Atitudes Alimentares Transtornadas, um questionário para avaliar comportamento de risco para transtornos alimentares (TA), além de questões de caracterização da amostra. Foram investigadas a associação entre a percepção de alimentação saudável e tipo de instituição, fase da graduação, sexo, estado nutricional, comportamento de risco para TA, satisfação corporal por meio do teste qui-quadrado; a relação entre a percepção de alimentação saudável e relacionamento com a comida por meio do teste de Mann Whitney; e a predição da percepção de alimentação saudável a partir das variáveis do estudo por meio de um modelo de Árvore de Classificação e Regressão. Resultados: Dos estudantes, 82,4% eram provenientes de instituições privadas, tinham em média 23,42 anos (DP=2,96), 93,4% eram do sexo feminino, 70,2% era eutrófica, 23,2% relataram algum comportamento de risco para TA, 85,0% estavam insatisfeitos com sua imagem corporal, 71,5% entendiam alimentação saudável exclusivamente do ponto de vista biológico e 28,5% consideravam alimentação saudável como um fenômeno biopsicossociocultural. A percepção de alimentação saudável esteve associada ao tipo de instituição de ensino e fase da graduação, sendo que estudantes de instituições públicas e no final da graduação, entendiam, em maior frequência, alimentação saudável como aquela que considera aspectos biopsicossocioculturais (p<0,001, para ambos). Não foram encontradas associações entre percepção de alimentação saudável e sexo (p=0,910), estado nutricional (p=0,552), comportamento de risco para TA (0,382) e satisfação corporal (p=0,352), nem relação entre percepção de alimentação saudável e relacionamento com a comida (p=0,159). A percepção de alimentação saudável pôde ser predita, com precisão de 66,4%, principalmente a partir do tipo de instituição, da percepção da função do nutricionista, do semestre da graduação, do nível de atividade física, do uso de artigos científicos como fonte de informação, da percepção corporal e da atitude com relação à manteiga, sendo o tipo de instituição de ensino o fator mais importante para classificar os estudantes segundo a percepção biológica e biopsicossociocultural da alimentação. Conclusão: A maior parte dos estudantes entende que a percepção de alimentação saudável está relacionada, principalmente, aos aspectos biológicos. Enquanto que uma parcela menor entende a alimentação saudável como um fenômeno biopsicossociocultural. A percepção de alimentação saudável esteve associada ao tipo de instituição de ensino e fase da graduação e não esteve associada a sexo, estado nutricional, comportamento de risco para TA, satisfação corporal e relacionamento com a comida. O estudo oferece como contribuição uma ferramenta para predição da percepção de alimentação saudável dos estudantes e uma reflexão sobre a formação do nutricionista, servindo de base para a proposição de estratégias de ensino que promovam a visão biopsicossociocultural da alimentação, saúde e Nutrição. / Introduction: Food is one of the determinants of health. Students of Nutrition, when graduated, will act based on their perception of healthy eating to promote, maintain and restore health through foods. Therefore, their perception of healthy eating, which is variable and influenced by multiple factors, can impact health and the current epidemiological scenario. Objective: to explore the perception of healthy eating among students of Nutrition in the state of São Paulo - Brazil. Materials and methods: a sample of 625 undergraduate students of Nutrition from 42 public and private institutions located in 25 municipalities of the state of São Paulo, participants of the Health Study of Nutritionists, answered online, a questionnaire with quantitative and qualitative approach developed to evaluate the perception of healthy eating, the Figure Rating Scales for Brazilian Adults, the subscale Relation with food of the Disordered Eating Attitude Scale, a questionnaire to evaluate risk for eating disorders (ED), and questions of characterization of the sample. We investigated the association between the perception of healthy eating and type of institution, graduation phase, sex, nutritional status, risk for ED, body satisfaction through the chi-square test; the relation between the perception of healthy eating and relationship with food through the Mann Whitney test; and the prediction of healthy eating perception from the study variables through a Classification and Regression Tree model. Results: Of the students, 82.4% came from private institutions, had a mean of 23.42 years (SD = 2.96), 93.4% were female, 70.2% had normal weight, 23, 2% reported some risk behavior for ED, 85% were dissatisfied with their body image, 71.5% considered healthy eating exclusively from a biological point of view and 28.5% considered healthy eating as a biopsychosociocultural phenomenon. The perception of healthy eating was associated with the type of institution and undergraduate phase, and students from public institutions and at the end of the undergraduate course understood, more frequently, healthy eating as the one that considers biopsychosociocultural aspects (p < 0.001, for both). There were no associations between healthy eating perception and sex (p = 0.910), nutritional status (p = 0.552), risk behavior for ED (p = 0.382) and body satisfaction (p = 0.352), nor relation between healthy eating perception and relationship with food (p = 0.159). The perception of healthy eating could be predicted with an accuracy of 66.4%, mainly from the type of institution, the perception of the function of the dietitian, the graduation semester, the level of physical activity, the use of scientific articles as a source of information, body perception and attitude towards butter, and the type of institution is the most important factor to classify students according to the biological and biopsychosociocultural perception of healthy eating. Conclusion: Most students understand that the perception of healthy eating is mainly related to biological aspects. While a smaller portion understands healthy eating as a biopsychosociocultural phenomenon. The perception of healthy eating was associated with the type of institution and graduation phase and was not associated with gender, nutritional status, risk for ED, body satisfaction and relationship with food. The study offers as a contribution a tool to predict the perception of healthy eating of students and a reflection on the formation of the dietitian, serving as the basis for proposing teaching strategies that promote the biopsychosociocultural view of food, health and Nutrition.

La vitamine K fait l’objet d’un intérêt croissant en regard du rôle qu’elle peut jouer dans la santé humaine hormis celui bien établi dans la coagulation sanguine. De plus en plus d’études expérimentales lui confèrent des fonctions dans le système nerveux central, particulièrement dans la synthèse des sphingolipides, l’activation de la protéine vitamine K-dépendante Gas6 et la protection contre les dommages oxydatifs. Toutefois, il demeure beaucoup moins bien établi si la perturbation de ces fonctions peut conduire à des déficits cognitifs. L’objectif principal de cette thèse est de vérifier l’hypothèse selon laquelle le statut vitaminique K des personnes âgées en santé est un déterminant de la performance cognitive. En vue de la réalisation de cet objectif, une meilleure compréhension des indicateurs du statut vitaminique K s’avérait nécessaire. Chacune des études présentées vise donc un objectif spécifique : 1) évaluer le nombre de rappels alimentaires de 24 heures non consécutifs nécessaire pour mesurer l’apport habituel de vitamine K des personnes âgées; 2) évaluer la valeur d’une seule mesure de la concentration sérique de vitamine K comme marqueur de l’exposition à long terme; et 3) examiner l’association entre le statut vitaminique K et la performance cognitive des personnes âgées en santé de la cohorte québécoise NuAge. Trois dimensions cognitives ont été évaluées soient la mémoire épisodique verbale et non-verbale, les fonctions exécutives et la vitesse de traitement de l’information. Cette thèse présente la première étude appuyant l’hypothèse d’un rôle de la vitamine K dans la cognition chez les personnes âgées. Spécifiquement, la concentration sérique de vitamine K a été associée positivement à la performance en mémoire épisodique verbale, et plus particulièrement au processus de consolidation de la trace mnésique. En accord avec les travaux chez l’animal et l’action de la protéine Gas6 dans l’hippocampe, un rôle spécifique de la vitamine K à l’étape de consolidation est biologiquement plausible. Aucune association significative n’a été observée avec les fonctions exécutives et la vitesse de traitement de l’information. Parallèlement, il a été démontré qu’une mesure unique de la concentration sérique de vitamine K constitue une mesure adéquate de l’exposition à long terme à la vitamine K. De même, il a été établi que six à 13 rappels alimentaires de 24 heures sont nécessaires pour estimer précisément l’apport de vitamine K des personnes âgées en santé. Collectivement, les résultats de ces deux études fournissent des informations précieuses aux chercheurs permettant une meilleure interprétation des études existantes et une meilleure planification des études futures. Les résultats de cette thèse constituent une avancée importante dans la compréhension du rôle potentiel de la vitamine K dans le système nerveux central et renforce la nécessité qu’elle soit considérée en tant que facteur nutritionnel du vieillissement cognitif, en particulier chez les personnes traitées par un antagoniste de la vitamine K. / There is an increasing interest in the potential roles of vitamin K in human health aside from the one well established in blood clotting. Notably, a growing number of experimental studies show that vitamin K has biological functions in the central nervous system, particularly in the synthesis of sphingolipids, the activation of the vitamin K-dependent protein Gas6, and the prevention of oxidative damage. However, it remains uncertain whether the disruption of these functions can lead to cognitive deficits. The main objective of this thesis is to test the hypothesis that vitamin K status is a determinant of cognitive performance in healthy older adults. In order to achieve this goal, a better understanding of vitamin K status indicators was needed. Accordingly, three studies are presented each aiming at a specific objective: 1) estimate the number of non-consecutive 24-hour dietary recalls needed to assess usual vitamin K intake; 2) determine whether a single measurement of serum vitamin K concentration is an adequate indicator of long-term vitamin K exposure; and 3) examine the association between vitamin K status and cognitive performance in healthy older adults from the Québec NuAge Study. Three cognitive domains were assessed namely verbal and non-verbal episodic memory, executive functions, and speed of processing. This thesis presents the first study providing support for a role of vitamin K in cognition in older adults. Specifically, serum vitamin K concentration was positively associated with performance in verbal episodic memory, particularly in the consolidation process of the memory trace. Consistent with rodent studies and the action of the protein Gas6 in the hippocampus, a specific role of vitamin K in memory consolidation is biologically plausible. No significant association was observed with executive functions and speed of processing. Additionally, it was established that a single measurement of serum vitamin K concentration is adequate for assessing long-term vitamin K exposure in healthy older adults. Similarly, it was determined that six to 13 24-hour dietary recalls are needed to accurately assess usual vitamin K intake. Collectively, both studies provide valuable information to researchers for better interpretation of existing studies and planning future ones. Results from this thesis constitute an important step in the understanding of the potential role of vitamin K in the central nervous system, emphasizing the need to consider this micronutrient as a nutritional factor of cognitive aging, especially among those treated with vitamin K antagonists.

Le but de cette étude consiste à démontrer l’impact positif d’une supplémentation en glutamine chez des nageurs élites, afin d’améliorer le statut immunitaire et d’évaluer si les changements plasmatiques de la glutamine peuvent expliquer l’incidence d’infections des voies respiratoires (IVRS). En parallèle, ce projet évalue si les apports alimentaires influencent la glutamine plasmatique et l’incidence d’IVRS. L’étude s’est effectuée auprès de 14 athlètes élites (8 hommes, 6 femmes). Chaque athlète a participé aux deux conditions expérimentales : un supplément de glutamine et une solution placebo isocalorique. Les périodes de supplémentation se déroulaient sur sept jours, incluant trois journées consécutives de compétition. Le profil hématologique, après les compétitions, montre qu’un supplément de glutamine n’améliore pas significativement la concentration plasmatique en glutamine ni les niveaux de cytokines comparativement à une solution placebo. Bien que les résultats soient semblables sous les deux conditions, les niveaux post-compétition ont tendance à être supérieurs aux valeurs pré-supplémentation, lorsqu’un apport exogène en glutamine est fourni à l’organisme alors que les concentrations plasmatiques de glutamine tendent à diminuer lorsqu’une solution placebo est administrée (p=0.067). L'incidence d’IVRS ne peut être expliquée par une faible concentration plasmatique de glutamine ni par un apport exogène de glutamine. On observe cependant une augmentation d’IVRS suite aux compétitions, soient de 8 athlètes pour le groupe placebo contre 3 au groupe glutamine. Les athlètes atteints d'IVRS semblent consommer moins d'énergie totale (kcal) et de protéines que les athlètes sains (p=0.060). Les résultats obtenus ne démontrent pas qu’une supplémentation en glutamine améliore le profil immunitaire et ne prévienne l’incidence d’IVRS, mais ils soulèvent l’hypothèse qu’un apport exogène en glutamine stabilise les niveaux plasmatiques de glutamine, permettant aux athlètes de poursuivre leurs entraînements et de récupérer efficacement. / The purposes of this study were to determine the positive impacts of glutamine supplementation upon immune system status and to determine whether changes in plasma glutamine relate to the appearance of upper respiratory tract infections (URTI) in elite swimmers. Furthermore, this study evaluated dietary intakes and its influence on immune parameters and URTI incidence. Fourteen athletes (8 men, 6 women) took part of the study. Each athlete participated in both experimental conditions: glutamine supplement and an isocaloric solution placebo. The supplementation period lasted seven day, including three consecutive competing days. Post competing hematologic profils of swimmers show that glutamine supplement does not significantly improve plasma glutamine neither cytokines levels, compared to a placebo solution. Even if plasma glutamine concentrations are similar with both conditions, the post competiting levels tend to be higher than pre competing values, when glutamine is supplemented. Futhermore, plasma glutamine levels show a decreasing trend under control conditions (p=0.060). In this study, URTI can not be explained by low plasma glutamine or supplemented glutamine. However, URTI incidence is higher after competitions, where 8 athletes showed symptoms (control group) and 3 only in the experimental group. Athletes with URTI seem to consume less energy and proteins than healthy athletes (p=0.060). These data does not suggest that glutamine supplementation improves immune function or prevents URTI in highly trained swimmers during competition. However, results support the hypothesis that exogenous glutamine stabilizes plasma glutamine levels, allowing athletes to tolerate training workload and recover properly.

La proprotéine convertase subtilisine/kexine type 9 (PCSK9) favorise la dégradation post-transcriptionnelle du récepteur des lipoprotéines de faible densité (LDLr) dans les hépatocytes et augmente le LDL-cholestérol dans le plasma. Cependant, il n’est pas clair si la PCSK9 joue un rôle dans l’intestin. Dans cette étude, nous caractérisons les variations de la PCSK9 et du LDLr dans les cellules Caco-2/15 différentiées en fonction d’une variété d’effecteurs potentiels. Le cholestérol (100 µM) lié à l’albumine ou présenté en micelles a réduit de façon significative l’expression génique (30%, p<0,05) et l’expression protéique (50%, p<0,05) de la PCSK9. Étonnamment, une diminution similaire dans le LDLr protéique a été enregistrée (45%, p<0,05). Les cellules traitées avec le 25-hydroxycholestérol (50 µM) présentent également des réductions significatives dans l’ARNm (37%, p<0,01) et la protéine (75%, p<0,001) de la PCSK9. Une baisse des expressions génique (30%, p<0,05) et protéique (57%, p<0,01) a également été constatée dans le LDLr. Des diminutions ont aussi été observées pour la HMG CoA réductase et la protéine liant l’élément de réponse aux stérols SREBP-2. Il a été démontré que le SREBP-2 peut activer transcriptionnellement la PCSK9 par le biais de la liaison de SREBP-2 à son élément de réponse aux stérols situé dans la région proximale du promoteur de la PCSK9. Inversement, la déplétion du contenu cellulaire en cholestérol par l’hydroxypropyl-β-cyclodextrine a augmenté l’expression génique de la PCSK9 (20%, p<0,05) et son contenu protéique (540%, p<0,001), en parallèle avec les niveaux protéiques de SREBP-2. L’ajout des acides biliaires taurocholate et déoxycholate dans le milieu apical des cellules intestinales Caco-2/15 a provoqué une baisse d’expression génique (30%, p<0,01) et une hausse d’expression protéique (43%, p<0,01) de la PCSK9 respectivement, probablement via la modulation du FXR (farnesoid X receptor). Ces données combinées semblent donc indiquer que la PCSK9 fonctionne comme un senseur de stérols dans le petit intestin. / Proprotein convertase subtilisin/kexin type 9 (PCSK9) posttranslationally promotes the degradation of the low-density lipoprotein receptor (LDLr) in hepatocytes and increases plasma LDL cholesterol. It is not clear, however, whether PCSK9 plays a role in the small intestine. Here, we characterized the patterns of variations of PCSK9 and LDLr in fully differentiated Caco-2/15 cells as a function of various potential effectors. Cholesterol (100 µM) solubilised in albumin or micelles significantly down-regulated PCSK9 gene (30%, p<0,05) and protein expression (50%, p<0,05), surprisingly in concert with a decrease in LDLr protein levels (45%, p<0,05). 25-hydroxycholesterol (50 µM) treated cells also displayed significant reduction in PCSK9 gene (37 %, p<0,01) and protein (75% p<0,001) expression, while LDLr showed a decrease at the gene (30%, p< 0,05) and protein (57%, p<0,01) levels, respectively. The amounts of PCSK9 mRNA and protein in Caco-2/15 cells were associated to the regulation of HMG-CoA reductase and sterol regulatory element binding protein-2 (SREBP-2) that can transcriptionally activate PCSK9 via sterol-regulatory elements located in its proximal promoter region. On the other hand, depletion of cholesterol content by hydroxypropyl-β-cyclodextrine up-regulated PCSK9 transcripts (20%, p<0,05) and protein mass (540%, p<0,001), in parallel with SREBP-2 protein levels. The addition of bile acids, taurocholate and deoxycholate, to the apical culture medium lowered PCSK9 gene expression (30%, p<0,01) and raised PCSK9 protein expression (43%, p<0,01) respectively, probably via the modulation of farnesoid X receptor. Combined, these data indicate that PCSK9 functions as a sensor of sterol in the small intestine.

L'exposition à la lumière des solutions de nutrition parentérale (NP) génère des peroxydes tels que l'H2O2 et l'ascorbylperoxyde (AscOOH). Cette absence de photo-protection provoque une augmentation des triglycérides (TG) plasmatique chez les enfants prématurés et chez un modèle animal, ayant un stress oxydatif et une stéatose hépatique indépendante de l’exposition au H2O2. Nous pensons que l'AscOOH est l'agent actif conduisant à l'élévation des TG. Le but est d'investiguer le rôle de l'AscOOH sur les métabolismes du glucose et des lipides à l'aide d'un modèle animal néonatal de NP. / The light exposure of parenteral nutritive solutions generates peroxides such as H2O2 and ascorbylperoxide. This absence of photo-protection is associated with higher plasma triacylglycerol concentration (TG) in premature infants and, in animals, with oxidative stress and a H2O2 independent hepatic steatosis. We hypothesized that ascorbylperoxide is the active agent leading to high TG. The aim was to investigate the role of ascorbylperoxide on glucose and lipid metabolism in an animal model of neonatal parenteral nutrition.

Introduction: Les aidants des personnes âgées (PA) atteintes de la démence de type Alzheimer (DTA) sont confrontés à de nombreux défis lors du soin de leurs proches, y compris ceux liés à l’alimentation. Cependant, ces défis restent méconnus et les stratégies créées pour les gérer sont encore peu efficaces. Objectifs: Identifier les difficultés rencontrées par les aidants pendant la gestion de l’alimentation des PA atteintes de la DTA ayant participé à une intervention nutritionnelle (l’étude NIS) et dégager leurs opinions concernant cette intervention. Sujets: Trente-trois aidants des PA avec DTA du groupe intervention de l’étude NIS ont été ciblés. Méthodes: L’approche qualitative a été employée lors des entrevues individuelles auprès de ces aidants. Les entrevues ont été transcrites et le verbatim fut soumis à une analyse thématique. Résultats: Vingt-quatre aidants ont été interviewés. Quelque 58,4 % avaient 70 ans et plus et 58,3 % étaient des conjoint (es) des patients affectés. Quatre catégories de thèmes furent dégagées menant à l’identification des défis alimentaires suivants: les changements des habitudes alimentaires (altération des préférences); les perturbations du comportement alimentaire (ex. l’oubli de repas); la dépendance à la préparation des repas. L’utilité des conseils, la gentillesse et la compétence du personnel NIS, la documentation écrite offerte et la durée du suivi ont été appréciées par les aidants. Conclusion: Une meilleure compréhension de l'expérience de soin vécu par l’aidant est essentielle au développement des interventions nutritionnelles adaptées aux besoins des aidants et des PA atteintes de la DTA. / Introduction: Caregivers of older adults suffering from Alzheimer disease (AD) are confronted by many challenges related to the care of their family members, including dietary management. However these challenges remain poorly understood by health professionals and strategies for managing these challenges are still not very effective. Objectives: To identify difficulties encountered by caregivers related to dietary management of their family members with AD taking part in a nutritional intervention (NIS study), and to gather their opinions about this intervention. Subjects: Thirty-three caregivers of older adults with AD were targeted from the NIS study intervention group. Methods: Using a qualitative approach, individual interviews were conducted with these caregivers, the verbatim was transcribed and a thematic analysis was carried out. Results: Twenty-four caregivers were interviewed. Some 58.4 % were 70 years old and older and 58.3 % were spouses of the patients. Four categories of themes emerged, leading to the identification of the following dietary challenges: changes in food habits (e.g. modification of food preferences); eating behavior disturbances (e.g.forgetting meals); dependence for meal preparation. The usefulness of the nutrition counseling, the kindness and the competence of the NIS personnel, the written material offered and the length of the follow-up were appreciated by the caregivers. Conclusion: A better understanding of the caregiver’s experience is essential for the development of nutrition interventions adapted to the needs of caregivers and older adults with AD.

Cette étude s’insère dans une étude s’intitulant « Choix alimentaires d’adolescents canadiens et attitudes de leurs entraîneurs impliqués dans des activités sportives organisées ». Les objectifs étaient d’étudier chez des adolescents impliqués dans une compétition sportive provinciale où l’offre alimentaire est contrôlée 1) leur maîtrise des recommandations nutritionnelles 2) les facteurs individuels, comportementaux, socio-environnementaux influençant leurs choix alimentaires. Deux observateurs ont visité les différents sites alimentaires et de compétition pendant les Jeux du Québec de 2011 à Valleyfield. Les plateaux des athlètes ont été photographiés à table au moment des repas avec une caméra numérique et les commentaires oraux colligés par écrit. Au total, 173 photographies ont été analysées et comparées aux recommandations reconnues en nutrition sportive. Dans notre étude, les préférences alimentaires, l’offre alimentaire et la présence des coéquipiers sont les facteurs qui influencent le plus les choix alimentaires en compétition. Par contre, le sexe de l’athlète n’a pas influencé les choix alimentaires des athlètes observés. En pré-compétition, 85,4% des plateaux présentent une valeur énergétique supérieure aux recommandations et 66,3% d’entre eux ont une répartition en énergie inadéquate, peu importe le sexe. Un excès de lipides et de protéines au sein du repas précédant l’effort caractérise majoritairement les plateaux dont la répartition en énergie est non optimale (69,5%). Les recommandations en post-compétition (100%) et lors des jours de repos (95,8%) ont facilement été rencontrées. Il en est de même pour l’hydratation (99,4%). Le lait au chocolat est la boisson la plus populaire (59,5%). Les produits céréaliers (99,4%), le lait et substituts (87,3%), les légumes (85,7%), les viandes et substituts (83,2%), les aliments riches en sucres (79,8%), les fruits (70,5%) et les mets riches en gras (59,4%) sont particulièrement appréciés par les athlètes. Les commentaires recueillis font ressortir une vision dichotomique des aliments chez certains athlètes qui classifient les aliments en « bons » ou « mauvais ». Notre étude démontre que la présence d’une politique alimentaire permet de promouvoir des habitudes alimentaires saines et favorise la consommation d’aliments nutritifs lors d’une compétition sportive d’envergure. Cependant, de l’éducation en nutrition est toujours requise pour viser l’amélioration du comportement alimentaire avant l’effort. / This study was part of the project entitled "Food choices of Canadian adolescents and attitudes of coaches involved in organized sports". The objectives were to assess in athletes involved in a provincial sport competition where the food supply is controlled 1) their compliance to dietary recommendations 2) the individual, behavioural, social-environmental factors influencing their food choices. Two observers visited food services and competition sites during the 2011 Quebec Games in Valleyfield. The athletes’ trays were photographed at the table during mealtime with a digital camera. Oral comments were collected. A total of 173 photographs were analyzed and compared to recognized sport nutrition recommendations. In this study, food preferences, food supply and teammates were the factors that influence the most food choices in competition. However, the sex of the athletes observed did not influence their food choices. 85,4% of the trays of the pre-game meal showed an energy value above the recommendations and 66,3% of them showed an inadequate distribution of macronutrients, regardless of gender. An excess of lipids and proteins within the pre-game meal characterized the trays when energy distribution was not optimal (69,5%). Recommendations in the post-competition phase (100%) and during rest days (95,8%) were easily met. The same observation can be made for hydration (99,4%). Chocolate milk is the most popular drink (59,5%). Grain products (99,4%), milk and alternatives (87,3%), vegetables (85,7%), meat and alternatives (83,2%), foods rich in sugar (79,8%), fruits (70,5%) and meals rich in fat (59,4%) are especially appreciated by athletes. Comments from the athletes dividing foods into "good" or "bad" showed a dichotomous view of food. Our study shows that established food policies help to promote healthy eating habits and to encourage consumption of nutritious foods during a major sporting event. However, nutrition education is still required to reach an improved food behaviour of athletes before exercise.