Vitamins/Supplements: How much is too much?

Recently I have been tightening up my diet, moving towards a 75% raw/vegetarian diet. Ive also been trying to formulate a vitamin, supplement plan.

Currently im taking a Centrum multi, 500mg Vit C (2x daily), 50mg Zinc, 1 tsp Royal jelly, and a combo powder of Chlorella, Bee Pollen, Wheat Grass, Barley and Spirulina.

So while reading up on a wide variety of vitamins, minerals and herbs, I came up with a list of a wide variety of things that I either don’t take entirely or likely don’t take enough of.

My question is how many vitamins and supplements are TOO much? On my list are about 16 things, beyond what im currently taking. (Vitamin E, Vitamin B complex, Magnesium, Manganese, Chromium, Selenium, Glutamine, Phenylalanine, Carnatine, Omega-3, Phosphatidyl serine, Ginko Biloba, Ginseng, Tumeric, Saw Palmetto, acai and a probiotic)

If I added all of that to my current regimen id have about 21 different things throughout the day.

So, is there harm taking too many vitamins and supplements?

What is considered an acceptable amount of supplements to take?

Also, what about mega multi vitamins? I was looking at a GNC mega multi that could cover quite a few of those in one supplement, but it seemed to have an extremely high level of some of the vitamins and nutrients. Seems like complete overkill, especially if you have a fairly clean, healthy diet.

Thanks in advance.