Table 2.

Summary of dietary folate deficiency and supplementation on DNA methylation in human studies

Study (reference)SubjectsDoseDurationDNA methylationEffect
Folate deficiency
    Rampersaud et al. (46)Women 60 –85 yr118 μg/day7 wkLeukocytes genomic10% decrease (P = 0.0012)
    Jacob et al. (45)Women 49–63 yr56–111 μg/day9 wkLymphocytes genomic120% decrease (P < 0.05)
    Jacob et al. (47)Men25 μg/day30 daysMethylation capacity (not DNA)No change
Folate supplementation
    Cravo et al. (8)Patients with CRC and adenoma10 mg/day6 moRectal mucosa genomic93% increase (P < 0.002)
    Cravo et al. (9)Patients with colonic adenoma5 mg/day3 moRectal mucosa genomic37% increase in patients with 1 adenoma (P = 0.05) and no change in those with >1 adenomas
    Kim et al. (11)Patients with colonic adenoma5 mg/day6 moRectal mucosa genomic57% increase (P = 0.001)
1 yrNo change
    Cravo et al. (52)Patients with inflammatory bowel disease5 mg/day6 moRectal mucosa genomicNo change
    Fenech et al. (48)Normal subjects2 mg/day12 wkLymphocytes genomicNo change