Since 1932 As Pyridoxine HCL Fresh · Healthy Once Daily Dietary Supplement Discussion: Vitamin B-6 functions as a coenzyme for more than 100 enzymes. Vitamin B-6 is necessary for the production of serotonin and other neurotransmitters. Vitamins B-6 promotes healthy cardiovascular function. Our own laboratory analysis guarantees purity and freshness of all Thompson products.