title: Folate intake and incidence of hypertension among American young adults: a 20-y follow-up study.
abstract: BACKGROUND
  Laboratory studies suggest that folate intake may decrease blood pressure (BP) through increasing nitric oxide synthesis in endothelial cells and/or reducing plasma homocysteine concentrations. However, human studies, particularly longitudinal data, are limited.
  
  
  OBJECTIVE
  Our objective was to investigate whether dietary folate intake is associated with the 20-y incidence of hypertension.
  
  
  METHODS
  We prospectively followed 4400 men and women (African Americans and whites aged 18-30 y) without hypertension at baseline (1985) in the Coronary Artery Risk Development in Young Adults study 6 times, in 1987, 1990, 1992, 1995, 2000, and 2005. Diet was assessed by dietary-history questionnaire at baseline and in 1992 and 2005. Incident hypertension was defined as the first occurrence at any follow-up examination of systolic BP ≥ 140 mm Hg, diastolic BP ≥ 90 mm Hg, or use of antihypertensive medication.
  
  
  RESULTS
  A total of 989 incident cases were identified during the 20-y follow-up. After adjustment for potential confounders, participants in the highest quintile of total folate intake had a significantly lower incidence of hypertension (HR: 0.48; 95% CI: 0.38, 0.62; P-trend < 0.01) than did those in the lowest quintile. The multivariable HRs for the same comparison were 0.33 (95% CI: 0.22, 0.51; P-trend < 0.01) in whites and 0.54 (95% CI: 0.40, 0.75; P-trend < 0.01) in African Americans (P-interaction = 0.047). The inverse associations were confirmed in a subset of the cohort (n = 1445) with serum folate measured at baseline and in 1992 and 2000.
  
  
  CONCLUSIONS
  Higher folate intake in young adulthood was longitudinally associated with a lower incidence of hypertension later in life. This inverse association was more pronounced in whites. Additional studies are warranted to establish the causal inference.
authors.affiliation: Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Xun
authors.forename: Kiang
authors.initials: K
authors.lastname: Liu
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Loria
authors.forename: Deborah
authors.initials: D
authors.lastname: Bujnowski
authors.forename: James M
authors.initials: JM
authors.lastname: Shikany
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Schreiner
authors.forename: Stephen
authors.initials: S
authors.lastname: Sidney
authors.forename: Ka
authors.initials: K
authors.lastname: He
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American; D001794:Blood Pressure; D004032:Diet; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood; D005500:Follow-Up Studies; D006710:Homocysteine / Q000097:blood; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D015994:Incidence; D007407:Interviews as Topic; D008137:Longitudinal Studies; D008297:Male; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014805:Vitamin B 12 / Q000097:blood; D025101:Vitamin B 6 / Q000097:blood; D044465:White People; D055815:Young Adult
chemical_list: D006710:Homocysteine; D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12