I don´t work in the mail service, but I don´t see any problem with it.
In proper package (perhaps it needs a stronger outer packaging, etc...) and the cost depending on the volume or weight (at least here is like this.)
As for the drug stuff, I don´t think they would think that, if so they would have tests, sniffing, and other ways to know.
Food isn´t allowed to some English-speaking countries, but chocolate sprinkles (or rainbow sprinkles, etc) wouldn´t be regarded as food.
Anyway, chocolate sprinkles could have a problem with heat or other issues, so wouldn´t hurt to see that information with the mail service itself.
On their end, and being domestic mail (inside their country) it seems easy.https://personal.help.royalmail.com/app ... -customershttp://www.correios.com.br/para-sua-emp ... restricoes