The Guardian has issued a correction to its September 26 article, “What is leucovorin, the drug the FDA approved to treat autism?”, after misstating a key health recommendation and misidentifying a vitamin. The original piece claimed that the Centers for Disease Control and Prevention recommends 400 milligrams of folic acid daily for those who may become pregnant and referred to folate as “vitamin B”. The paper later clarified that the actual figure is 400 micrograms — one-thousandth of the reported dose — and that folate is vitamin B9.

The slip may seem technical, but in the context of autism and prenatal health it is substantial. Misreporting 400 micrograms as 400 milligrams inflates the safe intake level by a factor of 1,000, a discrepancy that could leave readers with a dangerously inaccurate impression.