1-Benzyl-3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridin-1-ium Bromide is an intermediate in synthesizing 4-Pyridoxic Acid-d3 (P991877), an isotope labelled analog of 4-Pyridoxic Acid (P991875); which is a catabolite of vitamin B6 (P991735). Also a water-soluble B-group vitamin that can be used as a urinary diagnostic biomarker for determining the nutritional status of these vitamins.