Failure To Thrive?

I've been doing a lot of research on the whole experience, looking for recipes and food ideas. Today I wanted advice on how not to get so over-hungry as I did last night, and my Google wanderings turned up this article: http://www.beyondveg.com/billings-t/comp-anat/comp-anat-9b.shtml where the author talks about possible long-term unhealthy results from a vegetarian/vegan diet causing the same symptoms that are diagnosed in infants as "Failure To Thrive" (FTT). FTT is a general term that seem to more or less cover anyone who doesn't feel good but probably should be healthy. (Of course it's more defined than that, that's my paraphrase).

I can see how the lack of trace nutrients in a limited diet could cause this, but thinking about it, I'm wondering if the same FTT idea could be applied to people who eat a non-vegan but severely limited diet -- which in the US is a lot of people. With the amount and variety of food available to us every day, it's astonishing to me that anyone of even moderate income could actually be malnourished, but given what makes up the so-called "Standard American Diet" it's easy to imagine many people are missing out on trace nutrients.

Vegans know they need to supplement with B12 at the minimum, and also benefit from flax seeds and other items that are lacking from a wholly plant-based diet. On the other hand, most omnivores probably need to supplement their diets with plants (and eat less crap, but that's another topic). I find it interesting that maintaining this ultra-healthy diet plan depends upon introducing processed supplements and additives, and that's before even considering the heavily processed vegan food substitutes that are so common in the diet today.