<p>Inadequate nutrition in childhood can inhibit optimal growth and development, and is also associated with increased risk of chronic diseases later in life. Children living in households with limited financial resources may face a number of challenges to meet nutrient needs through unhealthy eating patterns, which may lead to health inequalities throughout the life-course. Therefore, improving low-income children’s diet would be an effective strategy for their health promotion and disease prevention, and potentially for narrowing health inequalities. The essential step for an efficient intervention would be to identify the unique nutrition risk that low-income children have. Therefore, the overarching aim of research in this dissertation was to identify nutrition risk of U.S. infants and children with low income or food insecurity, or participating in federal nutrition assistance programs using data from nationally representative surveys. An additional aim was to assess whether the inclusion of micronutrient intake from dietary supplements impacts micronutrient inadequacy in children. </p><p>For low-income infants and young children up to the age of 5 years, the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides tailored food packages to improve dietary intake that may be inadequate due to economic constraints. Therefore, it is expected that nutrient intake of WIC participants would be more like those of higher-income nonparticipants and higher than those of lower-income nonparticipants who are likely to be eligible for WIC. The results from the Feeding Infants and Toddlers Study 2016 data analysis supported the hypothesis for several nutrients of concern, although WIC participants were more likely to exceed the recommended limits for sodium and added sugars compared to higher-income nonparticipants. However, higher-income nonparticipants were more likely to use dietary supplements than both WIC participants and lower-income nonparticipants, which can impact total nutrient intake (i.e., nutrient intake from all sources). </p><p>Systematic differences in dietary supplement use by income and WIC participation were also observed in a nationally representative sample of children aged 18 years and younger from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). Dietary supplement use was lower among children in low-income families compared to those in higher-income families. Among children in low-income families, those participating in WIC were less likely to use dietary supplements compared to nonparticipants. In addition, food insecurity and the Supplemental Nutrition Assistance Program (SNAP) participation were associated with lower use of dietary supplements. Overall, one-third of children used any dietary supplements, mostly multivitamin-minerals, with primary motivations for use as “improve” or “maintain” health. </p><p>The following analysis of the 2011-2014 NHANES data showed that the inclusion of dietary supplements in nutrient intake assessments may lead to wider disparities in dietary intake by food security. This study also demonstrated the dose-response relationship between food security status and mean adequacy ratio, a summary measure of micronutrient adequacy. The mean adequacy ratio, inclusive of dietary supplements, was the highest in high food-security group (mean of 0.77), lower in marginal and low food security group (mean of 0.74), and the lowest in very low food security group (mean of 0.66), based on classification by food security among household children. However, the mean adequacy ratio does not reflect the usual intake (i.e., a long-term, habitual intake). </p><p>Therefore, another analysis of the 2011-2016 NHANES data estimated total usual nutrient intake of U.S. children 18 years and younger by food security status, using the National Cancer Institute method that adjusts for random error by statistical modeling. The results suggested that food insecurity was associated with higher risks of inadequate intakes for some nutrients, such as vitamins D and E and magnesium among boys and girls and vitamin A and calcium among girls only. Poor overall dietary quality and excessive sodium intake were of concern, regardless of food security status. </p><p>Collectively, the results from the studies in this dissertation add value to the evidence base about the adverse association of low income level and food insecurity status with dietary intake and extend the finding to include nutrient intakes from dietary supplements, which widens the disparity in nutrition risk. These findings highlight a need for interventions to reduce nutrient inadequacies and improve dietary quality among children across all socioeconomic levels, but especially among those with low income or food insecurity.</p><div><br></div>

Introdução - Os hábitos alimentares e os nutrientes da via metabólica do folato e homocisteína possuem grande importância na manutenção da saúde. Objetivo - Investigar a relação entre padrões alimentares (PAs) e os nutrientes envolvidos nessa via metabólica, com medidas antropométricas do recém-nascido, duração da infecção por HPV em homens e concentrações de homocisteína (Hcy) em adultos. Métodos - Foram utilizados dados dos estudos de coorte ProcriAr (Influência dos fatores nutricionais e poluentes atmosféricos urbanos na saúde pulmonar de crianças: um estudo de coorte com gestantes da zona oeste do município de São Paulo, n=299); e HIM (História natural da infecção por HPV em homens, n=1.194); e do estudo transversal ISA-Capital 2008 (Inquérito de saúde do estado de São Paulo, n=281). Os padrões alimentares foram derivados por análise fatorial por componentes principais nos estudos ProcriAr e ISA-Capital 2008 e utilizando reduced rank regression (RRR) no estudo HIM. Modelos multivariados de regressão de Poisson e lineares foram utilizados nos estudos ProcriAr e HIM para identificar a relação entre PAs e medidas antropométricas do recém-nascido e duração da infecção por HPV em homens, respectivamente. Utilizando modelo de equação estrutural, investigou-se a relação entre PAs, concentrações bioquímicas de folato, vitamina B12 e ácido docosahexaenoico (DHA) e concentrações de homocisteína em adultos do estudo ISA-Capital, considerando polimorfismo da enzima metilenotetrahidrofolato redutase (MTHFR 677C>T). Os três estudos utilizaram questionário de frequência alimentar para avaliação do consumo alimentar. Resultados - No estudo ProcriAr, a maior adesão materna ao PA \"Snacks, sanduíches, doces e refrigerantes\", rico em energia, gordura, e folato sintético, esteve diretamente associada a ter um filho pequeno ao nascer (peso e/ou comprimento ao nascer, ajustado pela idade gestacional, abaixo do percentil 10 - INTERGOWTH-21st) (RR: 2,01; IC 95%: 1.13-3.57). No estudo HIM, homens com maior adesão ao \"PA3\" tiveram, em média, um aumento de 1,15 (IC95% 0,09-2,21) à 1,18 (IC95% 0,11-2,24) meses na duração da infecção por HPV. O \"PA3\" esteve positivamente correlacionado com vitamina B6 (r = 0,59), vitamina B12 (0,27) e DFE (0,07) e negativamente correlacionado com DHA (-0,37). No estudo ISA-Capital o PA \"Prudente\" esteve inversamente associado à concentração de Hcy (&#946; = -0,12). O DHA esteve diretamente associado ao PA \"Prudente\"; composto por verduras e legumes, peixe, frutas, frango, suco natural e batata/mandioca/polenta (cozida ou assada). Conclusões - Os PAs estão associados às medidas antropométricas do recém-nascido, à duração da infecção por HPV em homens e às concentrações de homocisteína em adultos. Estes resultados reforçam a importância de estudos sobre alimentação e nutrição que considerem não somente nutrientes, mas principalmente o consumo de alimentos e suas combinações, servindo como base para a elaboração de estratégias e políticas públicas de promoção à saúde. / Introduction - The dietary habits and nutrients involved in one-carbon metabolism are of great importance in health. Objective - To investigate the relationship between dietary patterns (DP) and the nutrients involved in this metabolism, with newborn\'s anthropometric measurements, duration of HPV infection in men, and homocysteine (Hcy) levels in adults. Methods - Data from the cohort studies ProcriAr (Influence of nutritional factors and urban air pollutants on the pulmonary health of children: a cohort study with pregnant women from the western region of the city of São Paulo, n=299); and HIM (Natural history of HPV infection in men, n=1,194); and the cross-sectional study ISA-Capital 2008 (São Paulo State Health Survey, n=281) were used. The DP were estimated using factor analysis with principal component\'s estimation in ProcriAr and ISA-Capital 2008 studies and using reduced rank regression (RRR) in HIM study. Multivariate Poisson and linear regression models were used in the ProcriAr and HIM studies to identify the relationship between DP and newborn\'s anthropometric measurements and duration of HPV infection in men, respectively. Using a structural equation model, the relationship between DP, biochemical levels of folate, vitamin B12 and docosahexaenoic acid (DHA) and homocysteine levels was investigated in adults from the ISA-Capital 2008 study, considering the polymorphism of the enzyme methylenetetrahydrofolate reductase (MTHFR 677C>T). The three studies used a food frequency questionnaire to evaluate dietary intake. Results - In the ProcriAr study, the higher maternal adherence to the \"Snacks, sandwiches, sweets and soft drinks\" DP, which is a DP rich in energy, fat, and synthetic folate, was directly associated with having a child small at birth (weight and/or birth length by gestational age and sex below the 10th percentile - INTERGOWTH-21st) (RR: 2.01, 95% CI: 1.13-3.57). In the HIM study, men with higher adherence to \"DP3\" had, on average, an increase from 1.15 (95% CI 0.09-2.21) to 1.18 (95% CI 0.11-2.24) months in the duration of HPV infection. \"DP3\" was positively correlated with vitamin B6 (r = 0.59), vitamin B12 (0.27) and DFE (0.07) and negatively correlated with DHA (-0.37). In the ISA-Capital study, the \"Prudent\" DP was inversely associated with Hcy levels (&#946; = -0.12). DHA was directly associated with \"Prudent\" DP; composed of vegetables, fish, fruits, chicken, natural juice and potato/cassava/polenta (cooked or roasted). Conclusions - Dietary patterns are associated with newborn\'s anthropometric measurements, duration of HPV infection in men, and Hcy levels in adults. These results reinforce the importance of studies on food and nutrition that consider not only nutrients, but mainly the consumption of foods and their combinations, serving as a basis for the elaboration of public health promotion strategies and policies.