My toddler get fall sick more often.

If he has been falling sick often, yes it is advisable to take in more vitamins to boost immunity, eating healthy. I do have friends that has been putting child at CC or IFC and fall sick often. Perhaps due to low immunity or not consuming enough vitamins. You can buy of shelves at pharmacy with recommendations or get Transfer Factor 4Life website.

Try sambucol or kaloba syrup. Both worked for me