Effects of multivitamins and low-dose folic acid supplements on flow-mediated vasodilation and plasma homocysteine levels in older adults

Abstract

Background: Hyperhomocysteinemia is associated with aging, endothelial dysfunction, and increased risk of coronary heart disease in older adults; however, the effects of homocysteine-lowering therapy on vascular reactivity in older persons are unknown. The objective of this study was to determine the effects of multivitamins (MV) and folic acid (FA) supplements on flow-mediated vasodilation (FMD) in older adults.

Methods: Individuals > or =70 years old with homocysteine levels > or =10 micromol/L were recruited for this 40-week, prospective, single-blinded study. All subjects were treated sequentially, with each of the following daily therapies for 10 weeks: (1) placebo, (2) MV (400 microg FA, 6 mg vitamin B6, 25 microg vitamin B12), (3) placebo, then (4) MV + FA (total FA, 1400 microg). FMD, folate intake, and laboratory values were measured at each visit. Investigators were blinded to subject treatment phase when measuring vessel diameters and calculating FMD.

Results: Twenty subjects (mean +/- SEM age, 78.0 +/- 1.2 [range, 70 to 88] years, 9 women) completed the MV and 17 completed the MV + FA interventions. FMD was impaired at baseline (2.0% +/- 1.2%). During the 40-week study, homocysteine levels decreased by 1.4 +/- 0.9 micromol/L (p(trend) = 0.034) from a baseline of 12.8 +/- 0.6 micromol/L; however, FMD did not change significantly (p(trend) = 0.874). FMD did not improve after therapy with MV alone (3.0% +/- 0.9% [week 10] vs 2.4% +/- 1.1% [week 20], P =.716) or with MV + FA (2.6% +/- 0.9% [week 30] vs 1.9% +/- 0.7% [week 40], P =.484).

Conclusions: At doses commonly prescribed in clinical practice, MV and FA supplements did not improve FMD in older adults with hyperhomocysteinemia.