The safest is the simplest and the most natural : orange juice, containing ascorbic acid (vitamin C). This is also the case for lemon juice, parsley, red pepper, or blackcurrant, for example.

Thank you Fabrica Collin

Based on age of child you can prefer the antioxidants

if new born baby or upto 6 months better to avoid the antioxidants because at that stage baby getting immunity and antioxidant defence system of body. if you supplement out side antioxidants, the baby will not improves his/her defence system properly.

Thank you Ravi