Is It Dangerous To Take Vitamins And Herbal Supplements Together?

hello,i take a lot of vitamins and herbal supplements and someone told me mixing them is dangerous. if this is true, please tell me what i should eliminate.

morning:
ginkgo biloba
bilberry (4times a day)
cranberry fruit (4 times a day)
calcium
biotin
korean ginseng
iron

night:
valerian root (3 pills)thanks,