Any standards available for these foods like detail on which substances and what amounts may be added to these products? If yes, where can I get that information?

Yes. The information is available under the Food Safety and Standards (Health Supplements, Nutraceuticals, Food for Special Dietary Use, Food for Special Medical Purpose, Functional Food and Novel Food) Regulations, 2016 notified by FSSAI. The same is available on FSSAI website www.fssai.gov.in