Homocysteine metabolism and effects of folic acid supplementation in patients affected with spina bifida.

Folic acid supplementation around conception decreases the risk of having offspring with a neural tube defect. However, the aetiology is often still unknown. This study investigated whether spina bifida patients have lower blood folate and higher fasting and post-methionine-load plasma total homocysteine (tHcy) concentrations than control patients. Moreover, the effects of supplementation with 500 microg folic acid/d on folate and tHcy concentrations were determined. Spina bifida patients (n = 12) and disabled control patients (n = 15) received 4 weeks of placebo treatment followed by 4 weeks of intervention with 500 microg folic acid/d. Blood was collected at the start and after 4 and 8 weeks. A methionine-loading test was performed at the start and the end of the study. At baseline, no significant differences occurred between spina bifida and control patients. Folic acid supplementation significantly increased plasma and red blood cell folate concentrations in both groups. Folic acid decreased fasting tHcy concentrations in control patients by 1.6+/-0.5 micromol/l (p<0.01) and in spina bifida patients by 2.2 +/- 1.3 micromol/l (p = 0.10). This study does not show a derangement in homocysteine metabolism in spina bifida compared to control patients. Moreover, folic acid supplementation seems at least as effective in spina bifida patients as in controls.