[Hyperhomocysteinemia and alternate vitamin supplementation]

Treatment with folic acid and vitamin B 12 appears to be effective in lowering total plasma Homocysteine (tHcy) concentration, but whether vitamin B 12 alone decreases tHcy in patients with normal vitamin B 12 status is still unknown. The aims of the present study were to explore the effect of alternate vitamin supplementation with folic acid or vitamin B 12 on tHcy concentrations in haemodialysis (HD) patients, and to compare changes in tHcy concentrations with MTHFR genotype.

74 patients, 44 men and 30 women, were recruited and randomized blindly into two groups of 37 subjects each. The first group was initially treated with vitamin B 12 for two months, and with folic acid for the following two months; the second group was supplemented in the reverse order. In both groups the treatment was followed by a 2-month washout period. tHcy levels were measured at the beginning of treatment (T0), after two months (T1), four months (T2), and at the end of the washout period (T3). Vitamin B 12 and folate were taken at T0 and T3.

The genotype frequency was: C/C 37%, C/T 34%, T/T 29%. tHcy decreased in both groups following the alternate vitamins therapy. This decrease was greater for the T/T genotype (p<0.05) and was more significant when the treatment start-ed with folic acid (p<0.01). Moreover, after the washout period, tHcy increased remarkably without significant differences between diffusive and convective techniques. Folate levels at the end of study appeared to be reduced in haemodialysis patients. Vitamin B 12 concentration significantly increased in patients on diffusive haemodialysis, confirming the fundamental role of membrane performance.

The alternate vitamin treatment demonstrated the importance of folate therapy and the secondary contribution of vitamin B 12 in lowering tHcy in HD patients.