Of course many people under 50 need B12. I know people in their 20s who've incurred much damage because so much of the medical community is so ignorant.

As I suggested in my former post. I hope all noticed that the "or" was bolded:

People who have symptoms or are over 50 should consider at least 1000 mcg at a time, because some degree of malabsorption is common by that time.

It is certainly possible that nail health will be impaired with deficiency and improve with B12 treatment. But nail condition cannot diagnose or rule out B12 deficiency.

rose