One reason people don't see results with supplements is because the dose is too low. The RDAs are what it takes to prevent the most severe disease from a deficiency of whatever nutrient. For example, the RDA of iodine is 150 mcg that is the amount needed to prevent you from growing a goiter. A top doctor who specializes in iodine recommends 12 mg that is 80 times the RDA as that's how much the body needs to be able to do it's job a day. Same with vitamin C--the RDA is 60 mg that is just enough to keep you from dying from scurvy and your teeth from falling out.

Another reason is that not every supplement is effective for every person just as not every med helps every person. No one blames the doctor when a drug doesn't help them, but if a supplement isn't effective, most people swear off supplements claiming they're a waste of money. If a person wants to use supplements, they need to study the subject so they have an idea of what each supplement helps with. When I went on supplements after going off meds, I tried supplements based on what each nutrient helped with, and what I was experiencing. That's all a doctor does.