Relation of Diet to Serum Homocysteine Level in Youths
Condition: Cardiovascular Diseases; Heart Diseases; Atherosclerosis
MeSH terms: Cardiovascular Diseases; Heart Diseases; Atherosclerosis
Study type: Observational

Summary: 
      To examine the relation between diet and plasma total homocysteine levels in an ethnically
      and geographically diverse cohort of adolescents.
    

Detailed description: 
      BACKGROUND:

      Data from observational studies suggest that plasma total homocysteine (tHcy) concentration
      may be an independent and modifiable risk factor for cardiovascular disease (CVD) in adults.
      Plasma tHcy levels respond rapidly to nutrient supplementation with folic acid and vitamins
      Bl2 and B6, alone or in combination. The available data and the potential for prevention
      provide a strong rationale for understanding determinants of tHcy in youth. However, no large
      U.S. studies have examined the relation between tHcy levels to individuals' dietary intakes
      of folic acid and vitamins Bl2 and B6 in youth.

      DESIGN NARRATIVE:

      During the Child and Adolescent Trial for Cardiovascular Health (CATCH) Phase 3, a
      cross-sectional study of serum tHcy levels was conducted in eighth grade students (Jan-June
      1997). Higher mean levels of plasma total homocysteine were observed among males, Blacks, and
      non-users of multi-vitamins and a strong, inverse association with serum levels of folic acid
      and to a lesser extent, with serum vitamin Bl2. A second measurement of the cohort at grade
      12 was conducted in order to assess the dose-response relation between serum tHcy and dietary
      intakes (not measured in grade 8) of folic acid, vitamin B12 and vitamin B6. In addition and
      of equal importance, changes were evaluated in serum folic acid and tHcy levels from grade 8
      to 12, after full implementation of fortification of cereal and grain products in the U.S.
      with folic acid and its impact on the distribution of tHcy levels in adolescents described.
      Effective January 1, 1998, the U.S. Department of Agriculture mandated the addition of folic
      acid to all flour and grain products in the United States. CATCH had a unique opportunity to
      examine the effect of "this natural experiment" on the distribution of serum tHcy in the
      cohort, because serum tHcy levels were measured in grade 8, just prior to full implementation
      of the mandate. Furthermore, the study had adequate sample size to examine these changes
      among important demographic subgroups such as, males vs. females and Caucasians vs. African
      Americans vs. Hispanics. Information generated by this study will be valuable for designing
      specific dietary interventions for youth and targeting subgroups of children who may be at
      higher risk for CVD.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The CATCH study initially recruited 5,106 third grade students to participate in a risk
        factor screening at baseline. Of these, 3645 (71%) participated in risk factor screening at
        the end of grade 8 when serum tHcy, folate, vitamin B6 and vitamin B12 were first assessed
        and 2909 (57%) students participated in the follow-up risk factor screening in grade 12. Of
        these students, 2445, attended both grade 8 and grade 12 examinations and provided blood at
        both examinations. This group constituted the study population for this report.