Data from: Interaction of serum vitamin B12 and folate with MTHFR genotypes on risk of ischemic stroke

Abstract Objective We evaluated the interaction of serum folate and
vitamin B12 (B12) with methylenetetrahydrofolate reductase (MTHFR) C677T
genotypes, on the risk of first ischemic stroke, and on the efficacy of
folic acid (FA) treatment in prevention of first ischemic stroke. Methods
A total of 20,702 hypertensive adults were randomized to a double-blind
treatment of daily enalapril 10mg and FA 0.8mg or enalapril 10mg alone.
Participants were followed-up every three months. Results Median values of
folate and B12 concentrations at baseline were 8.1 ng/mL and 280.2 pmol/L,
respectively. Over a median of 4.5 years, among those not receiving FA,
participants with baseline serum B12 and/or serum folate above the median
had a significantly lower risk of first ischemic stroke (HR, 0.74; 95%CI:
0.57-0.96), especially in those with MTHFR 677 CC genotype (wild type)
(HR, 0.49; 95%CI: 0.31-0.78). FA treatment significantly reduced the risk
of first ischemic stroke in participants with both folate and B12 below
the median (2.3% in enalapril-folic acid group vs. 3.6% in enalapril-only
group; HR, 0.62; 95%CI: 0.46-0.86), particularly in MTHFR 677 CC carriers
(1.6% vs. 4.9%; HR, 0.24; 95%CI: 0.11-0.55). However, carriers of TT
responded better with both folate and B12 levels above the median (HR,
0.28; 95%CI: 0.10-0.75). Conclusions The risk of first ischemic stroke was
significantly higher in hypertensive patients with low levels of both
folate and B12. Effect of FA treatment was greatest in patients with low
folate and B12 with the CC genotype, and with high folate and B12 with the
TT genotype.