Low folate status increases chromosomal damage by X-ray irradiation.
OBJECTIVE
To examine how folate status influences chromosomal damage following X-ray irradiation.


METHODS
In an animal study, mice were fed either a low, basal, or high folic acid diet (0, 2, or 40 mg/kg diet, respectively) for 4 weeks, and then given total body irradiation (TBI) at 0.5 Gy. In a human study, subjects were supplemented with folic acid (800 microg/day) for 2 weeks and their peripheral blood was irradiated at 0.5 Gy in vitro. Chromosomal damage was determined by micronucleus assay.


RESULTS
In an animal study, TBI-induced chromosomal damage was higher and folate concentration was lower in the bone marrow of the low folic acid group compared to the other two diet groups. The chromosomal damage and folate concentration were comparable between the basal and high folic acid groups. TBI administered to mice decreased folate in the plasma, erythrocyte and bone marrow. In a human study, supplementation with folic acid increased plasma folate, but did not influence either plasma homocysteine or X-ray-induced chromosomal damage in lymphocytes.


CONCLUSIONS
Low folate status increases susceptibility to X-ray-induced chromosomal damage, but excessive folic acid supplementation under normal conditions yields no further protection due to folate saturation in the target tissue.
Endoh
Kaori
K
Department of Domestic Science, Kyoritsu Women's University, Chiyoda-ku, Tokyo, Japan.
Murakami
Masahiro
M
Araki
Risa
R
Maruyama
Chizuko
C
Umegaki
Keizo
K
D000284:Administration, Oral; D000328:Adult; D000818:Animals; D002478:Cells, Cultured; D002869:Chromosome Aberrations / Q000187:drug effects* / Q000528:radiation effects*; D002875:Chromosomes / Q000187:drug effects* / Q000528:radiation effects*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects; D011837:Radiation-Protective Agents / Q000008:administration & dosage; D014916:Whole-Body Irradiation / Q000009:adverse effects
D011837:Radiation-Protective Agents; D005492:Folic Acid