Each year, supplement brands fall over themselves to sell us products with the (asterisked) promise that they will boost immunity and provide protection through cold and flu season. Second, similar to how you can’t target belly fat specifically, we can’t isolate our immunity, because the immune system isn’t just one thing. “The immune system is a highly complex network, involving components like the spleen, white blood cells, the lymphatic system, the gut microbiome, and even our skin.