Greengage
I hear a lot of people swear by magnesium butter. You apparently rub some into the soles of your feet before you go to sleep.
I have a magnesium spray that you can use on your feet but I have to admit I never used to feel that it helped at all. I assume the dosage would be quite low from the spray so maybe that's why.
The butter would at least make your feet nice and soft at the same time 


