We have no concept today what that means, "eating for kedusha (holiness)." When it says, "Tov haeitz l’maachol — The trees were good for eating" in Gan Eden, it meant it was good for Adam...
If he would have remained in Gan Eden he would have achieved by means of the fruits of Gan Eden the most perfect results which Hashem had hoped to have from him. The sweetness of the fruits and the beauty of the fruits all combined for the purpose of achieving the summit, the acme of daas Elokim (knowledge of Hashem). — Repenting in Happiness (#E-160)