From what I know, most of the vitamin c on the market originates from China - NutraBiotic has pharmaceutical grade vitamin C that comes from the UK and I do not think its origin is corn-based. This is the only vit c I use now - However I like SuperC by Rainbow - has a nice blend of synergistic antioxidants (polyphenols etc) - there are some natural vitamin C powders I like as well - they use plant based like camu camu etc.