. "Any process that stops, prevents, or reduces the frequency, rate or extent of the chemical reactions and pathways resulting in the formation of thiamine." . . . . . . "negative regulation of thiamine biosynthetic process" . "down regulation of thiamine biosynthetic process" . "down-regulation of thiamine biosynthetic process" . "downregulation of thiamine biosynthetic process" . "inhibition of thiamine biosynthetic process" . "negative regulation of thiamin biosynthetic process" . "negative regulation of thiamine anabolism" . "negative regulation of thiamine biosynthesis" . "negative regulation of thiamine formation" . "negative regulation of thiamine synthesis" . . .