When both folate (folic acid) and b12 are low, which should you start to take first, and why?

B12: Less folate (folic acid) won't leave you with brain damage. Truth be told, though, as one of tomorrow's physicians you already know you don't treat lab values. Look at "why" the person is deficient. Many vegetarians lack both, despite all the talk. Look for malabsorption, and especially for pernicious anemia and if in any doubt, start the B12 injections right away.

B-12 first: Treating a B-12 deficient patient with folate (folic acid) may correct the anemia, but not stop the progression of irreversible nerve damage. It masks the B12 deficiency, in other words.

Low b12, folate (folic acid): Folic acid and b12 deficeincy cause macrocytic anemia. If you have deficincy of B12 and folic acid, you should replace both along with iron and vitamin C.

B12: always take the b12 first, folate (folic acid) may mask b12 deficiecny and the neurolgoical dmaage from b12 deficecny can be permanant.