Can taking vitamin d turn hair yellow?

The normal yellowish-amber color of urine is mainly due to a chemical called urochrome or urobilin, which is produced from the breakdown of heme.

Vitamin D itself is white and, as far as I can find, doesn't have a particularly notable effect on urine color.

Some vitamins can affect urine color... B vitamins, for example, can produce a vibrant, almost fluorescent yellow or green color, and vitamins A and C can turn urine orangish.

If you're concerned about drug testing, using foreign substances to impart a "normal" color to diluted urine will only fool a cursory visual inspection (if that... the B-vitamin yellow looks, to the trained eye, "odd" compared to the normal color produced by urobilin).