Stress gobbles up a lot of vitamins, including the B family, which are often dubbed (along with many others) as "stress vitamins". Pain is stress, so it's no wonder that many/most chronic/intactable pain patients take ample/liberal dosages. Vitamin D is another that is now being researched and associated with chronic pain.

Some B complex caplets can also brighten urine, but that may be the result of dyes in their formulations and/or insufficient hydration.

Doc