When taking mms can you eat right after?

my little brother has autism so we are trying the mms drops, we found on one site that you're not meant to eat anything that contains vitamin c within 4 hours of taking drops, but he doesnt understand and he really wants to eat. We can't fond many food without vitamin c. So is it okay if he eats, or will it cause bad side affects or slow the process down? thanks, help would really be appreciated.