I only got a bit of grey hair in my 30ies, not before.
I remember reading that copper and tyrosine can help to re-pigment the grey hair. From googling around, Iron might be helping too.
Anecdote: Since starting to supplement copper sometimes (see nanna1's immune stack) I got a compliment for getting tanned. I don't know if it influences the hair.
"Thyroid hormone and bromocriptine (an anti-prolactin drug) are two other therapies known to produce re-pigmentation in scalp hair."https://criticalmas.org/2013/09/reversing-gray-hair-part-2/After orgasm, dopamine goes down and prolactin goes up.
High prolactin is a cause of headache and has been discussed in other threads here.
Tyrosine is a precursor for Dopamine, bromocriptine seems to also work on Dopamine somehow