Vitamin B1 (7)
I believe the answer is:
thiamin
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">vitamin b1</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that vitamin b1 can be written as Thiamin)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for thiamin that I've seen before include "Vitamin B 1" , "Vitamin in cereals, beans, etc" , "Essential nutrition" , "vitamin required" , "food ingredient" .)