In 1938, the Great depression was still stinking up the joint, financially speaking, and lots of people didn't have enough to eat. Enter Ironized yeast Tablets to help plump up our women!
Anemia, due to vitamin deficiency, like iron, and vitamin B-12. Symptoms include fatigue, and moanings of "Ow! Such anemia I have! Harken to my plea! My kingdom for iron!" People talked like that in the thirties, right?
So, yeast helps you gain weight and Vitamin B increases appetite. Got it. Why don't we see many ads like this now? Well, number one, though times are tough, it ain't the Great Depression. Number two, with the advent of fast food in the fifties, cheap, calorie-rich foods can be found within a few feet of every television set (fact exaggerated for your enjoyment), so most people can fill their belly, but with shitty food prepared by people who hate their jobs. So, fatness is a problem now.
Also, vitamin deficiencies are much less common than they were in 1938, due to the fortification of many foods. This means that manufacturers try to sneak a few extra nutrients into stuff we eat every day, like flour and rice, which is handy. Odds are, you get plenty of every vitamin from the food you eat. Here is an excellent article from Colorado State University explaining popular myths about vitamins such as "you should take them". There is no evidence that taking vitamins has any effect on health at all, unless your suffering from a few specific conditions. More and more, it is looking as though vitamins are much more effective when they are eaten in food and not when they are crammed into a pill.
Also, dosing yourself with vitamins can cause loads of health problems if you take too much.
The "dietary supplement" industry is not regulated the same as actual food and medicine. The rules are much more lax. Here's a good bit from the link (from the FDA) in the previous sentence:
"Generally, manufacturers do not need to register their products with FDA
nor get FDA approval before producing or selling dietary supplements"
As it stands right now, you can practically sell bullets with leprosy sprinkles, and so long as you label it as a "dietary supplement", you have no obligation to prove it actually does anything - just so long as it's safe when used as directed. In the case of the leprosy bullets, you'd be within the limits of the dietary supplement laws as long as the directions on your package clearly state that you are to bury them in a cube of concrete several hundred feet underground and not to eat them or remove them from the package. (Hazmat suit sold separately).
This ad has a nice Disembodied Floating Head. He's supposed to be convincing and trustworthy... you know, like a doctor, but they don't even give him a name or say who he's supposed to be. He's just a head, staring at us, telling us we're too skinny. He looks kind of lascivious, like he's the creepy old perv whose job it is to ogle the women at Ionized Yeast HQ and tell them whether they look good or not. I bet he thinks they're all positively yummy.