Short-term folic acid supplementation induces variable and paradoxical changes in plasma homocyst(e)ine concentrations.

Folic acid is presently the mainstay of treatment for most subjects with elevated plasma homocyst(e)ine concentrations [Plasma or serum homocyst(e)ine, or total homocysteine, refers to the sum of the sulfhydryl amino acid homocysteine and the homocysteinyl moieties of the disulfides homocystine and homocystein-cysteine, whether free or bound to plasma proteins.] Changes in homocyst(e)ine in response to folic acid supplementation are characterized by considerable interindividual variation. The purpose of this study was to identify factors that contribute to heterogeneity in short-term responses to folic acid supplementation.

Increased plasma homocyst(e)ine after withdrawal of ready-to-eat breakfast cereal from the diet: prevention by breakfast cereal providing 200 microg folic acid.

Objective: We tested the hypothesis that cessation of habitual ingestion of breakfast cereals would be associated with elevated plasma homocyst(e)ine concentrations. We anticipated that those subjects who reported consuming breakfast cereals containing 100 to 400 ,microg of folic acid per serving before entering the study would achieve higher plasma homocyst(e)ine concentrations if, in addition to their regular diet, they began ingesting a daily serving of breakfast cereal that contained less than 10 microg of folic acid per serving.

Design: Seventy-nine subjects consumed a daily serving of breakfast cereal containing either < 10 microg or folic acid per serving (placebo) or breakfast cereal containing 200 microg of folic acid per serving (folic acid fortified).