Serum folate is a reliable indicator of hyperhomocysteinemia and borderline hyperhomocysteinemia in young adults.

Serum folate has been shown to correlate well with fasting plasma homocysteine; however, erythrocyte folate concentration is a better index of tissue folate stores and probably could be a more reliable indicator for reflecting long-term supply of the vitamin and homocysteine status. The present study was undertaken to test the hypothesis that serum folate and erythrocyte folate levels had a different degree of correlation to fasting plasma homocysteine in young Taiwanese adults. This study had a cross-sectional design. Healthy young adults were divided into either a hyperhomocysteinemia (HHcy; > or =14.9 micromol/L; n = 13), borderline HHcy (BHcy; fasting homocysteine, 14.9-10.2 micromol/L; n = 52), or normohomocysteinemia (fasting homocysteine, <10.2 micromol/L; n = 65) groups based on fasting homocysteine levels. The concentrations of plasma fasting homocysteine, serum folate, erythrocyte folate, vitamin B(12), and plasma pyridoxal 5'-phosphate were measured. Fasting homocysteine was only significantly and inversely affected by serum folate (beta = -0.21, P < .05) concentration after adjusting for potential confounders. Only serum folate concentration remained to decrease the risk of fasting HHcy (odds ratio, 0.73; confidence interval, 0.56-0.95) after the other B vitamins were additionally adjusted. Serum folate also had the highest area under the receiver operating characteristic (AUC) curve to predict the risk of HHcy (AUC, 0.81) and BHcy (AUC, 0.77). Serum folate is a reliable indicator of fasting hyperhyperhomocysteinemia and BHcy in young adults.