Given that is the case now it was even more the case in the past where ailments from missing nutrients were far more common than today.
Meaning that has always been an issue.
It's a variable issue, specifically one that is different between geological regions and, more importantly, economic status of the locality/region/country.
Specifically, nutritional impacts are typically only found in poor regions/countries, or during particularly troubling times (such as a major devastation to the food industry in some way, like droughts or any catastrophic events to the food supply, or even political to some degree... devastating wars are a good example too)...
tell me, based on that, SHOULD this be happening in America? It's not exactly a major phenomenon anywhere else in the
developed world.
A lot of this could almost be considered a result of how America came to be and in general what we've been through; we are a very young country, and rose to global prominence too fast. Especially having done so during the time we did... with so much happening across many industries (much of it, honestly, thanks to the US in many ways, if not due all credit), the way of life and the level of global interaction has really changed how everything works... our speedy rise has caused some issues.
Without turning this into some lengthy argument for an off-topic point, the main gist is that we've screwed ourselves into nutritional issues that should otherwise not even be a topic up for discussion.
Oh, and our FDA's guidance for proper nutritional balance is extremely outdated, based on research data that we now know
* to be off the mark... couple that with improper nutrition for our livestock, and well... we've seen how much national health (across the board) has changed in the past few decades.
* : for the most part; as I admitted earlier, the amount of research making positive correlations is indeed growing and fairly extensive, but still young. Additionally, this is "global knowledge" that I speak of, and not specifically just late-blossoming research in the U.S.; the fact that other countries have done better in this regard can almost be considered coincidence, but there is far more at play. Sadly, our ways (the ill-informed was) are also slowly spreading to other countries, though the timing of that influence is definitely better in their cases; that is, of course, if they adjust as we continue to expand our physiological and biochemical knowledge.