Nutr Res Pract.  2009 Jun;3(2):122-127.

Effects of dietary supplementation of high-dose folic acid on biomarkers of methylating reaction in vitamin B12-deficient rats

• Min H

Abstract

Folate is generally considered as a safe water-soluble vitamin for supplementation. However, we do not have enough information to confirm the potential effects and safety of folate supplementation and the interaction with vitamin B12 deficiency. It has been hypothesized that a greater methyl group supply could lead to compensation for vitamin B12 deficiency. On this basis, the present study was conducted to examine the effects of high-dose folic acid (FA) supplementation on biomarkers involved in the methionine cycle in vitamin B12-deficient rats. Sprague-Dawley rats were fed diets containing either 0 or 100 microg (daily dietary requirement) vitamin B12/kg diet with either 2 mg (daily dietary requirement) or 100 mg FA/kg diet for six weeks. Vitamin B12-deficiency resulted in increased plasma homocysteine (p<0.01), which was normalized by dietary supplementation of high-dose FA (p<0.01). However, FA supplementation and vitamin B12 deficiency did not alter hepatic and brain S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations and hepatic DNA methylation. These results indicated that supplementation of high-dose FA improved homocysteinemia in vitamin B12-deficiency but did not change SAM and SAH, the main biomarkers of methylating reaction.

Keyword

Folic acid supplementation; vitamin B12-deficiency; homocysteine; DNA methylation

MeSH Terms

Animals
Biomarkers
Brain
Compensation and Redress
Diet
Dietary Supplements
DNA Methylation
Folic Acid
Homocysteine
Hyperhomocysteinemia
Methionine
Plasma
Rats
Rats, Sprague-Dawley
S-Adenosylhomocysteine
S-Adenosylmethionine
Vitamin B 12 Deficiency
Vitamins
Folic Acid
Homocysteine
Hyperhomocysteinemia
Methionine
S-Adenosylhomocysteine
S-Adenosylmethionine
Vitamins

Figure

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  Fig. 1 Effect of high-dose FA supplementation on plasma homocysteine in rats fed vitamin B12-adequate or vitamin B12-deficienct diets in a 2×2 design. Values are expressed as means with their standard errors depicted by vertical bars (n=8). Two-way ANOVA; FA supplementation, p<0.01; vitamin B12, p<0.01. Different superscripts are significantly different at p<0.05 by Duncan's multiple-range test.

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