I don't have anything to back up the extra VE and Calcium supplements but I would imagine it's on the same lines as why you need extra Vitamin C.
Most of the multi-vitamin supplements only include 60mg of vitamin C, which is 100% recommended daily value (according to the FDA). What most people don't realize is that the recommended daily value is the MINIUMUM amount of vitamin C you need each day to prevent scurvy. Unfortunately most people don't even get the 60mg per day and are living in a state of sub-clinical scurvy. Most experts agree that an average person should be getting 500 - 3,000mg per day to optimize the use of C.
In my own personal case, I take one multi-vitamin a day and at least one 1,000mg vitamin C supplement a day. I haven't been sick since I started this over a year ago. Before that, I would be sick on average about 5 time per year.