A method for determining a folate substance administration regime is disclosed. The method comprises: quantifying, in a sample drawn from a patient, the expression level of at least one of the genes SLC46A1, SLC19A1, FPGS, ABCC3, MTHFD1 L, GGH, MTHFD1, MTFMT, and ATIC； and establishing whether the expression level is high or low. A high expression level of at least one of said genes determines that said folate substance administration regime involves the administration of [6R]-methylenetetrahydrofolate and/or a folate substance upstreams of [6R]-methylenetetrahydrofolate in the metabolic pathway. A low expression level of at least one of said genes determines that said folate substance administration regime involves the administration of [6R]-methylenetetrahydrofolate. Also disclosed is a kit for determining such a folate substance administration regime.
