Update 8/30/19. A friend asked me about Isotonix supplements and wanted to know my thoughts about them. Isotonix is a product line of phytonutrients (plant nutrients) called OPCs that are found naturally in fruits, vegetables, red wine, and other plants. OPC stands for oligomeric proanthocyanidins. So, do you need OPC supplements? Are Isotonix supplements better than other supplements? Let's see …