This was one of the earliest vitamin-fortified confections ever. The wrapper says that a bar of Vita-Sert gives you "100% of minimum adult requirements of listed vitamins" - not all vitamins, just some: B1, B2, C and D. Just the first four letters of the alphabet. Anything after D, you're on your own.
Best of all, if you sent the Cook Chocolate Company of Chicago (who clearly favored the letter C) a dime and 3 Vita-Sert wrappers, they would send you the "Pocket Guide For Vitamin Hunters." That's to help you find all the rest of the vitamins that you didn't get in your candy bar, I guess.
I always wish I could send away for the stuff advertised in old ads, and this is no exception - because who wouldn't love to be a Vitamin Hunter? I picture myself with a deerstalker hat and a large magnifying glass, examining things in the kitchen. Examining all the chocolate in shops, hoping against hope that I'll find ones packed with vitamins.
This ad (which I have just pinned on my Pinterest board, Chocolate Chronicles - the link will take you there) is quite similar to the one on the left, but features the exquisite verse, "Be Alert - Eat Vita-Sert" - and a cartoon girl before and after.
Parents' Magazine and Good Housekeeping were on board with Vita-Sert, too. In fact Good Housekeeping promised they would give you a fresh bar if you thought your Vita-Sert was "defective" or "not as advertised therein" - which sounds like kind of a bad idea, because those are pretty subjective terms. "I ate a Vita-Sert and I did not become alert! Please send me more!"
Actually, that really happened in 1943. There was a libel case filed against Cook Chocolate Co. in 1943 with reference to 367 cases of Vita-Sert. The bars were labeled as giving you all your daily vitamins and that just was - well, wrong. The FDA made them relabel - the ad above is from ca 1946, and is pretty careful to say the bars contain "needed vitamins" - not all of them.