Folate has important beneficial effects on endothelial function, but there is limited information about folate intake and risk of incident hypertension.
Dr Forman and colleagues from Boston, America designed a study in order to determine whether higher folate intake is associated with a lower risk of incident hypertension.
The researchers used data from 2 prospective cohort studies.
The first included a total of 93,803 younger women aged 27 to 44 years from the Nurses’ Health Study II (1991-1999).
The second study that the research team examined involved 62, 260 older women aged 43 to 70 years in the Nurses’ Health Study I (1990-1998).
The researchers ensured that none of the participants had a history of hypertension.
The research team gathered baseline information on dietary folate and supplemental folic acid intake from semiquantitative food frequency questionnaires and this was updated every 4 years.
The investigators calculated relative risk of incident self-reported hypertension during 8 years of follow-up.
The researchers identified a total of 7,373 incident cases of hypertension in younger women and 12,347 cases in older women.
The research team found that, after adjusting for multiple potential confounders, younger women who consumed at least 1000 µg/d of total folate (dietary plus supplemental) had a decreased risk of hypertension compared with those who consumed less than 200 µg/d.
|Older women’s absolute risk reduction was approximately 6 cases per 1000 person-years|
In addition, they noted that younger women’s absolute risk reduction (ARR) was approximately 8 cases per 1000 person-years (6.7 vs 14.8 cases).
The multivariable relative risk for the same comparison in older women was 0.82.
The researchers found that older women’s ARR was approximately 6 cases per 1000 person-years (34.7 vs 40.4 cases).
When the analysis was restricted to women with low dietary folate intake (<200 µg/d), the team found that the multivariable relative risk for younger women with total folate intake of at least 800 µg/d compared with less than 200 µg/d was 0.55 and 0.65 in the older cohort.
The researchers commented "Among women who did not take folic acid–containing supplements, dietary folate intake of 400 µg/d or more was not significantly associated with risk of hypertension."
Dr Forman concluded, "Higher total folate intake was associated with a decreased risk of incident hypertension, particularly in younger women."