Things like Vitamin C, Colloidal Silver, Iodine are less harmful than radiation, and have communities around those substances to promote their effectiveness.
Just because a group of people vouch for the beneficial properties of these 'remedies' and 'cure-alls' doesn't mean they actually do anything. In fact, colloidal silver is more dangerous than helpful. Silver builds up in the body and can cause all sorts of adverse reactions, including permanent argyria (blue colored skin).
Colloidal silver is not, and has never been dangerous. The old kind of Colloidal Silver with the larger particle sizes may have had a risk of turning skin blue if you drank gallons of it, as some people have. But it was never lethal. The modern kind of Colloidal Silver is made with nano-sized silver particles and can flow in and out of cells cleanly. There is no risk of silver building up in the skin. No one has gotten blue skin with modern silver products.
Did you know that Colloidal Silver was the antibiotic of choice before antibiotics were invented? The health benefits of silver had been known for centuries. Royalty and the rich ate and drank from silver utensils and were rarely sick. The Greeks and Romans used to store all of their perishable liquids in silver containers. Prior to the invention of refrigeration, it was common practice to drop a silver coin into a container of milk to retard spoilage. It was used during the Civil War for wound infections.
When the first commercially available antibiotics became available Colloidal Silver was dropped from the medical field like a bag of rocks. There is no profit in Colloidal Silver, and so no reason to give it to people when there is an alternative to profit from. The FDA, a tool of the pharmaceutical companies, engaged in a smear campaign, highlighting the few people who took Colloidal Silver in excess, in an effort to ban the substance from consumer use. But the campaign was too late. There was, and still is, a lot of demand in silver, by survivors of numerous incurable diseases, fueled by catalogs of miraculous survival stories dating hundreds of years, that the product remains on the shelf.
You are assuming, without good evidence, that there is no upper bound to the immune system's ability to fight off infection.
The upper bounds to the body's ability to fight off disease is unknown, but we know that people with Stage 4 cancer, on their deathbeds and given 2 weeks to live, have seen complete turn around via Vitamin C.
Some people at that stage, on the other hand, have not been cured. Whether their immune systems were too weak and crippled by any chemotherapy they had done, the disease, or whether they just didn't get enough Vitamin C, is unknown.
What do you do about infection's that trick the immune system in to thinking that it is not an infection? What do you do about an infection that kills the immune system?
Secondly, infections don't trick the immune system into thinking that it is not an infection. This is a falsity of the medical system, used to explain mysteries such as why women can have yeast infections but have normal blood white blood cell counts. If there was infection, white-blood cell counts should be elevated as the body fights off the disease, but this is not seen in a yeast infection.
The body doesn't go into overdrive when there is a yeast infection because it is not an infection, but an overgrowth due to a failing somewhere in the immune system. Yeast is not an opponent, but a friend. The body lives in symbiotic harmony with yeast, and needs it to survive, just like the other kinds of friendly bacteria that live within us. Something in the body which inhibits the yeast failed, usually because resources were diverted to combat another disease, and the yeast overgrew to cause the irritation. The body isn't going crazy to deploy killer T-cells with a fingerprint of the yeast stamped on the homing beacon, because yeast is a friend, there is some risk to doing that, and it has worse things to worry about than some easily reversed smelly irritation that will be resolved once the more dangerous secondary condition is dealt with. By taking Vitamin C, the secondary condition the body is fighting can be resolved and the body can then resort resources to ensure that everything is in balance again.
What do you do about an infection that kills the immune system?
If your immune system were killed off you would be dead within 20 minutes. Nothing can be done, because you are a gonner.