Eligible participants , stratified by MTHFR C677T genotypes ( CC , CT , and TT ) , were randomly assigned to receive double-blind daily treatment with a single-pill combination containing enalapril , 10 mg , and folic acid , 0.8 mg ( n = 10,348 ) or a tablet containing enalapril , 10 mg , alone ( n = 10,354 ) .