“It was found that the porphyrin production after i.p injection of 200 mg kg(-1) ALA or MAL was significantly increased by i.p injection of 100 mg kg(-1) folic acid.”
“Two mechanisms may explain the results: enhancement of the efficiency of the rate-limiting enzyme porphobilinogen deaminase by folic acid or interference of folic acid with the transport of ALA and MAL to and into the cells synthesizing porphyrins in the tissues.”