Vitamin supplements for poor diets are supposed to reflect an amount meeting physiologic requirements.
When something is given in pharmacologic doses to treat a precancerous lesion, in this case leukoplakia, this vitamin is now a drug because of the dose.
I'm not a pharmacist, but I had to study pharmacology.
I think the FDA classifies this as a food don't they ?
I believe you are correct. My vitamin bottle lists 400 mcg as the RDA for Folic Acid. In the study, they were giving 5000 mcg three times a day. At that mega dose level, I can see why they would want to monitor the person taking that amount.