Optimal GI contains citrus fiber. Is it okay to take if I have histamine sensitivity?

Citrus fiber is different than citrus itself. The fiber is not known to contain or liberate histamine. 

But keep in mind histamine intolerance and sensitivity can vary person-to-person, and therefore many foods that may be okay for some are not okay for others. As always, talk to your qualified healthcare professional before considering the use of this product to determine if its right for you.