Most doctors frown upon vitamins because they're taught in school the only way to good health is through pharmaceuticals and mercury-laden innoculations. At the same time, doctors know very little in the way of proper nutrition, as that indeed makes up very little of their overall schooling. I work in a hospital and I can't tell you how many doctors I see who smoke, are overweight and eat all kinds of garbage, etc. Doctors are not all-knowing gods. The diets of most Westernerns are devoid of the nutrients needed to maintain total health, so it's hard to day what exactly "eating healthy" is. A lot of people may think they're eating healthy, when in fact they are eating GMO foods that have been radiated and treated with all sorts of chemicals and preservatives that actually hamper the immune system.
Right now, I take greens plus, vit D, Vit C, Omegas and fish oil, a multivitamin, and florasil vegetal silica. I am considering green tea extract as well.
for a while I was taking B, C, fish oil, and niacin everyday. I don't know why I stopped. but for the record I didn't feel any different not taking them, as opposed to taking them...
my mom told me the day she was going to the doctor that she was going to be bringing home a new diet for her to do...and when she did and i read through what he wrote for her was actually prett damn good for a doctor...because like you said, majority of doctors have shit to do with learning proper nutrition in their courses. a bit too much anti-carb for my taste, but that can be worked with for the short term and then build back into eating carbs...so i'm not too worried and neither is my mom. more people should look to what they are eating first before adding in any sort of supplement.