The 40-day-old baby can't supplement zinc and calcium gluconate, because the 40-day-old baby relies on breast milk to supplement zinc and calcium, because I am the mother of a three-year-old child and a child nutrition expert. 40-day-old babies can't supplement zinc and calcium. Cousin's child asked me at the age of 40: Cousin, can my son give him some grape zinc and calcium now? I gave her the answer, no, the 40-day-old baby relies on breast milk to supplement zinc and calcium. Please mark my words!