SECOND EDITION - Updated February 2026
In September 2025, leucovorin went from a niche clinical interest to front-page news. The FDA announced a label update. The White House held a press conference. Parents who had never heard of cerebral folate deficiency were suddenly asking their paediatricians about it.
Then the largest trial supporting leucovorin for autism was retracted.
This book is my attempt to give you an honest account of where the evidence stands now - what has held up, what has not, and what remains genuinely uncertain. I explain the biology in plain language, walk through the published trials (including the one that fell apart), and set out what I think a careful clinician should be doing with this information today.
I am a Consultant Community Paediatrician with nearly forty years of NHS experience and the clinical lead for autism diagnostic services in my Trust. I am also the parent of autistic children. I have no financial interest in leucovorin and no relationship with any manufacturer.
If you are looking for promises, this is the wrong book. If you want to understand the science well enough to have a proper conversation with your child's doctor, read on.
Dr Odet M. Aszkenasy FRCP (Lon.), DCH, MFPHM