METHODS

Design:

randomised placebo controlled trial (Folic Acid and Carotid Intima media Thickness [FACIT] trial).

Allocation:

concealed.*

Blinding:

blinded {clinicians, participants, data collectors, outcome assessors, data safety and monitoring committee, manuscript writers, and data analysts/statisticians}†.*

Follow up period:

3 years.

Setting:

Gelderland province, the Netherlands.

Participants:

818 men and postmenopausal women 50–70 years of age (mean age 60 y, 72% men) recruited from municipal and blood bank registries who reported ⩾80% compliance during a 6 week placebo run in period. 51 participants had 1 household member who was also enrolled and received …