It depends on the type of orange juice you are using. Fresh OJ would provide plenty of Vit. C to interact with the Lugols. Frozen OJ becomes questionable as to how much Vit. C is really in it. First, the OJ in frozen OJ has been heat processed to prevent spoilage. Heat destroys Vit. C. Then, the longer it is frozen, what Vit. C is in it gradually declines, and again, the same for when you mix it with water. The longer that pitcher of OJ sits in your refrig, the less Vit. C it has in it. They can put on the label the amount of Vit. C that was in the original fresh OJ (prior to processing), but what you really get at the end of the consumer line is another story. Since I dilute my OJ twice as much as the can calls for, the Lugols darkens it a tad. That tells me there isn't enough Vit. C. in it to knock out all the iodine. I also use other juices purchased from the health food store and have noticed the the Lugols changes/darkens that juice as well.