So he/she will be remineralizing with:
Epsom salt - magnesium sulfate heptahydrate (MgSO4•7H2O)
Baking Soda - Sodium Bicarbonate (NaHCO3)
I suggest scanning this thread for posts by Rob1.
The epsom salts are apparently safe for human consumption, assuming that the product is pure with no additives and no other impurities. There are suppliers that sell food grade (UPA, if my memory serves me correctly) magnesium sulfate.
Fyi, Rob1 uses magnesium hydroxide, as he does not like the taste (or I suppose smell) of sulphate.
He also uses the sodium bicarbonate in his recipe, which apparently is quite safe for human consumption.
Please also see our conversation on the need for frequent and separate flushing of the brew and service boilers.