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Master's Dissertation
DOI
10.11606/D.6.2010.tde-17112010-120013
Document
Author
Full name
Josiane Steluti
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2010
Supervisor
Committee
Marchioni, Dirce Maria Lobo (President)
D'Almeida, Vania
Martini, Ligia Araujo
Title in Portuguese
Folato, vitamina B6 e B12: Ingestão dietética, níveis sanguíneos e relação com a concentração sérica de homocisteína em adolescentes de Indaiatuba, SP
Keywords in Portuguese
Adolescentes
Consumo Alimentar
Homocisteína
Marcadores bioquímicos
Nutrição
Vitaminas
Abstract in Portuguese
Introdução: O folato e outras vitaminas do complexo B estão metabolicamente relacionadas à elevação sanguínea do aminoácido homocisteína (hcy). Este, por sua vez, se mostrou associada ao aumento de risco de eventos adversos, sobretudo as doenças cardiovasculares. Objetivo: Investigar a ingestão dietética e níveis sanguíneos das vitaminas folato, B6, e B12, e sua relação com a concentração sérica de hcy, entre adolescentes Métodos: Estudo observacional, transversal, em adolescentes de ambos os sexos, faixa etária de 16 a 19 anos, foi conduzido na escola de ensino técnico da cidade de Indaiatuba-SP-Brasil. Coletou-se registro alimentar de três dias não consecutivos. Os valores dos nutrientes referentes aos registros foram obtidos no software NDSR. Para a estimativa da dieta habitual pela remoção da variabilidade intrapessoal e a prevalência de inadequação da ingestão pelo método da EAR como ponto de corte, utilizou-se o PC-Side, versão 1.0. As análises bioquímicas de folato, B6, B12 e hcy foram conduzidas de acordo com os métodos aceitos na literatura científica. Todas as análises estatísticas foram realizadas no STATA® versão 10.0 considerando o nível de significância 5%. Resultados: O estudo foi conduzido com 99 adolescentes, sendo 58,6% do sexo feminino e média de idade de 17,6 (dp 0,9) anos. As médias da concentração sérica de folato, B6 e B12 foram de 9,2 (dp 3,4) ng/ml, 18,7 (dp 5,1) nmol/L e 397,5 (dp 188,4) pg/ml, respectivamente. 15,2% dos adolescentes apresentavam inadequação da ingestão de folato, 10,2%, de B6 e <1%, de B12. Os alimentos que mais contribuíram para a ingestão dos nutrientes foram: pão francês (23,1%), macarrão (9,7%) e feijões (8,2%) para folato; arroz branco (9,9%), carne de frango (5,7%) e carne bovina (4,2%) para B6, e carne bovina magra (16,4%), leite integral (15%) e carne bovina gorda (12,3%) para B12. Em relação à hcy, as médias foram de 15,4 (dp 10,2) µmol/L nos meninos e 8,2 (dp 2,2) µmol/L nas meninas. Dos meninos, 25% apresentavam valores séricos de hcy superiores a 15 µmol/L e diminuição da média sérica de folato e B12 quanto maior o tercil do nível sérico hcy (p<0,005). Conclusão: As prevalências de inadequação da ingestão folato, B6 e B12 mostraram-se baixas, possivelmente em decorrência da melhoria do acesso e disponibilidade de alimentos, inclusive dos alimentos processados que contêm entre os ingredientes as farinhas fortificadas com ácido fólico. No entanto, os feijões, ainda se destacaram como um dos alimentos que contribuíram para a ingestão desse nutriente. Além disso, os adolescentes do sexo masculino têm altos níveis séricos de hcy e apresentaram uma tendência de queda das médias da concentração sérica de folato e B12 quanto maior o tercil de hcy.
Title in English
Folate, vitamin B6 and B12: the relationship between serum homocysteine concentration and dietary intake and status of vitamins among adolescents of Indaiatuba, São Paulo.
Keywords in English
Adolescents
Biomarkers.
Food Consumption
Homocysteine
Nutrition
Vitamins
Abstract in English
Introduction: Folate and the metabolically related B vitamins are intimately connected with metabolic pathways of homocysteine (hcy). Epidemiologic studies have shown that increased total homocysteine concentration is an independent predictor for a number of human diseases, especially, cardiovascular diseases. Objective: to investigate the dietary intake and status of folate, related B-vitamin, and the relationship to total homocysteine concentration among adolescents. Methods: A cross-sectional study was conducted among adolescents, both genders, aged 16 to 19 years, in a public school of Indaiatuba, São Paulo. Dietary intake was measured using three-day dietary record. The energy and nutrients were computed using Nutrition Data System for Research software. The usual intake and prevalence of inadequate by EAR cut-point method were estimated using PC-SIDE, version 1.0. Biochemical analyses were determined according the methods recommended by the scientific literature. All statistical analyses were performed using STATA, version 10.0. A two-tailed p value <0.05 was considered significant. Results: The study was conducted among 99 adolescents, 58 (58.6%) were girls, mean age of 17.6 (SD 0.9) years old. The means of folate, B6 and B12 vitamins status were of 9.2 (SD 3.4) ng/ml, 18.7 (SD 5.1) nmol/L and 397.5 (SD 188.4) pg/ml, respectively. The proportion of adolescents with folate, B6 and B12 intakes above the recommendation was 15.2%, 10.2%, e <1%, respectively. The foods that more contributed for folate intake were French bread (23.1%), pasta (9.7%) and beans (8.2%). For B6 intake rice (9.9%), chicken (5.7%) and meat (4.2%). For B12 intake, meat without fat (16.4%) whole milk (15%) and meat with fat (12.3%). The mean of hcy was 15.4 (SD 10.2) µmol/L in boys and 8.2 (SD 2.2) µmol/L in girls. In boys, 25% of them showed values of serum hcy concentration upper to 15 µmol/L and, means of folate and vitamin B12 decreased according of serum hcy tercil (p<0.005). Conclusions: The prevalence of inadequate intake of folate, vitamin B6 and B12 were low, possibly due to improved access and availability of food, including processed foods that contain the fortified flour with folic acid as ingredient. However, the beans, a component of the Brazilians usual dietary pattern, are founded as important contributors of folate intake. The total homocysteine levels were higher in boys when compared with girls. In boys, folate and vitamin B12 status were decreased significantly with trend among different tercile serum homocysteine concentration.
 
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Publishing Date
2010-12-21
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • STELUTI, Josiane, et al. Folate, vitamin B6 and vitamin B12 in adolescence: serum concentrations, prevalence of inadequate intakes and sources in food [doi:10.2223/JPED.2056]. Jornal de Pediatria [online], 2011, vol. 87, n. 1, p. 43-49.
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