May one take flavored vitamins that don’t have a hechsher but that all of it’s ingredients don’t warrant a concern that there is anything not kosher in them (they are made in America.) What is the reason why yes or why not?
One should not take flavored vitamins unless they have a hechsher or at least that a kashrus professional has gone through the ingredients, to verify that everything inside it is kosher. Flavored vitamins are more problematic than other non kosher vitamins, since the person is benefitting from the taste of the non kosher item, and also more problematic that medicins because often they are not taken because of a medical illness..
The fact that something was produced in America does not in any way say that the ingredients are kosher. The food industry has become very large, and complicated. The large kashrus agencies now have data bases in order to keep track of over 100,000 different types of ingredients from every continent, and country in the world, that can go into foods, vitamins, etc. Besides there is also the issue of the machinery used to make them.
Here are some issues that can arise with vitamins: glucosamine can come from lobsters or shrimp, calcium from oysters, vitamin A or d from shark oil, Vitamin B from pork, and zinc from shellfish. For more examples see R’ Blumenkrantz’s , “The Laws of Pesach”.