Have you ever gone out for a ride that puts grey/white into your hair/beard overnight (literally)?
I went out a few months ago for a ride that was well beyond my ability (I had 2 months off and was over excited with a new bike). Then I woke up the next day with 7 white stubs on my chin. Plucked them off, but they kept on coming back.
What's up with this? Vitamins deficiency? What's the popular theory?