QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Jacob, R. A. Articles by Swendseid, M. E. Search for Related Content PubMed PubMed Citation Articles by Jacob, R. A. Articles by Swendseid, M. E.

Homocysteine Increases as Folate Decreases in Plasma of Healthy Men during Short-Term Dietary Folate and Methyl Group Restriction^{1, 2, 3,}

Western Human Nutrition Research Center, U.S. Department of Agriculture, Agricultural Research Service, Presidio of San Francisco, CA 94129 ^* School of Public Health, University of California, Los Angeles, CA 90024

Ten healthy adult men were fed a diet low in folate and exogenous methyl groups to study the effects on folate requirement and status. The men were housed in a metabolic unit for the entire 108-d study. After a 9-d base-line period (P1), the men were fed an amino acid-defined soybean product diet for 45 d, which provided 25 µg/d of folate for 30 d (P2) and (with a folate supplement) 99 µg/d for 15 d (P3). During P2 and P3, the low methionine and choline diet was supplemented with methionine for half the subjects to vary the dietary methyl group intake. The periods were then repeated over the next 54 d (P4–P6), with a cross-over of methionine intakes in P5 and P6. Restricting dietary methyl group intake did not increase the dietary folate requirement. Plasma total homocysteine rose during folate depletion and correlated inversely with plasma folate; however, the response of homocysteine to changes in folate intake varied among individuals from very strong to absent. The results support previous suggestions that increased plasma homocysteine concentrations provide a marker of functional folate deficiency, and further indicate that individuals may differ greatly in their susceptibility to hyperhomocysteinemia due to low folate intakes. Judged by the lack of normalization of high homocysteine concentrations during folate repletion, the current folate RDA for adult men may not provide the expected margin of protection.

KEY WORDS: • folic acid • methyl group • homocysteine • methionine • humans

¹ Project at UCLA supported in part by NIHCA42710 and Westreco Inc., Van Nuys, CA.

² Reference to a company or product name does not imply approval or recommendation of the product by the U.S. Department of Agriculture to the exclusion of others that may be suitable.

³ The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 USC section 1734 solely to indicate this fact.

⁴ To whom correspondence should be addressed.

Manuscript received 8 November 1993. Revision accepted 10 May 1994.