Across 7 studies, 6 reported beneficial effects of Vitamin B9 supplementation on reducing homocysteine levels, with a predominant effect size ranging from small to moderate. Most evidence comes from randomized controlled trials and meta-analyses in clinical populations (e.g., coronary heart disease, type 2 diabetes) and healthy adults, with doses typically around 1 mg/day and effects observed at 8–12 weeks. The median study duration was 84 days, indicating sustained supplementation is typical for achieving reductions.
Caveats: BeneficialCount is 6 of 7 (≥85%) — clinical literature in this area is subject to publication bias (null-result studies are less likely to be published or indexed). One neutral study in children with sickle cell disease suggests the effect may not generalize to pediatric populations or those with certain comorbidities. Most trials were relatively short (4–12 weeks); longer-term effects are less documented.
folate showed an excellent safety and tolerability profile with only one adverse event reported among 1367 individuals.
from: Folate Supplementation for Peripheral Neuropathy: A Systematic Review.Folate significantly decreased homocysteine
The folic acid and l-5-MTHF groups had 17% and 15%, respectively, lower (P < 0.001) plasma total homocysteine concentrations than did the placebo group at 12 wk; there were no differences between the folic acid and l-5-MTHF groups.
Combined B-vitamin supplementation significantly reduced serum Hcy levels [mean difference: -2.36; 95% CI: (-3.09 to -1.62); p < 0.01]
There were no significant differences observed in 1-carbon metabolite concentrations (total homocysteine...).
Folic acid supplementation significantly revealed a large effect size on homocysteine levels compared to placebo, SMD = -1.53, 95%CI (-2.14,-0.93), p < 0.05.
Furthermore, supplementation of vitamin B-12, vitamin B-6, and folic acid successfully reduced high homocysteine concentrations that emerged from levodopa metabolism
In both groups, a significant decrease in the mean Hcy level after intervention period was observed.