So what kind of effect do they actually have?

 

I guess they fall into two categories. The first is stuff like multivitamins, that give your full optimal daily value of pretty much all the vitamins and minerals you need. These seem like they would have to be beneficial, although I'm not sure how much difference they make in a generally non-malnourished person. Do we tend to get most of that stuff anyway?

 

The second category is the "herbal" stuff, like ginseng, ginko baloba, etc. I'm under the impression that it's all just placebo nonsense. Am I correct in that? Or is there actual evidence that that stuff does anything? If so, what does it do, exactly?

multivitamins don't really affect a person with a well balanced diet as they will get all the vitamins from the food they eat the key is "well balanced".

 

the herbal stuff is mostly placebo although there are a few things around that do have verified active ingredients although the effect is still small because of the small dosages and they don't usually do anything useful just a bit of slight mood altering or reducing a headache.