How many letters does the top answer for “a b vitamin that is used to treat pernicious anemia” have?

The most common answer is cobalamin (9 letters).

Crossword clue: a b vitamin that is used to treat pernicious anemia

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

cobalamin 9 letters wn-def

a B vitamin that is used to treat pernicious anemia

cyanocobalamin 14 letters wn-def

a B vitamin that is used to treat pernicious anemia