text:  Is that multivitamin you're taking every day really helping you live longer? Here's what CBS's Bradley Blackburn found out. Researchers looked at data on more than 400,000 healthy U.S. adults over 20 years and found no differences in mortality or risk of death for those who took multivitamins versus those who did not. Ahead of the opening bell on Wall Street, the Dow is up 13. This is CBS News.