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

Folic acid supplementation around conception decreases the risk of having o ffspring with a neural tube defect. However, the aetiology is often still u nknown. This study investigated whether spina bifida patients have lower bl ood folate and higher fasting and post-methionine-load plasma total homocys teine (tHcy) concentrations than control patients. Moreover, the effects of supplementation with 500 mug folic acid/d on folate and tHcy concentration s were determined. Spina bifida patients (n =12) and disabled control patie nts (n = 15) received 4 weeks of placebo treatment followed by 4 weeks of i ntervention with 500 mug 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 signi ficantly increased plasma and red blood cell folate concentrations in both groups. Folic acid decreased fasting tHcy concentrations in control patient s by 1.6+/-0.5 mu mol/l (p<0.01) and in spins bifida patients by 2.2+/-1.3 <mu>mol/l (p = 0.10). This study does not show a derangement in homocystein e metabolism in spina bifida compared to control patients. Moreover, folic acid supplementation seems at least as effective in spina bifida patients a s in controls.