The civil war claim is pretty weak. There was no refrigeration in those days (at least in the field). The soldier's provided nutrition mostly came from hardtack and salted pork/bacon/beef. They also had stuff like dried peas and beans. At some point the union soldiers had some access to condensed milk.

The soldiers bought stuff (or were preyed upon) by various camp followers selling more stuff.

Generally speaking, the South had a weak supply chain, so they were more often to go without. I think that fact spoke more to the eventual Union victory.... industrial economies can absorb more punishment than a agrarian slave economy.

Bioavailability is rather complicated: for any given nutrient it can be enhanced by the presence of certain other nutrients but diminished by others.

Your comment also ignores phytonutrients* (which includes flavonoids and some anti-oxidants) and the effects of diet on gut flora, both of which topics we are just beginning to understand.

This is why, until we really understand the nitty-gritty of all of the hundreds (thousands?) of chemicals contained in food and how they interact, the best recommendations involve eating a variety of foods, both fresh and cooked.

* http://extension.psu.edu/health/news/2012/the-importance-of-...

And then, there's the (IMO certain) outcome that, when we come to "really understand," we'll realize that "eating a variety of foods, both fresh and cooked" is the most economically viable option for keeping optimal health, when there is access to a healthy natural environment.

Have there been any meta-analyses on the effects of phytonutrients? A recent analysis on antioxidants failed to disprove the null hypothesis (no effect) for most of them other than Vitamin D.

This article points out problems with unbalanced vegetarian and vegan diets. A balanced one is not that hard to achieve, there are many good resources that give you examples of such varied diets. If well done, supplements are unnecessary apart from vitamin B12. Even B12 doesn't need to be in pills: vegans can get it from marmite/vegemite, and vegetarians from eggs and diary.

That being said, it's still advisable to check for deficits, of course.

> Of course, people still need protein. You won't get that from a cheap vitamin pill, and it's tricky to do right with a vegan diet

Not really - lentils, beans, peas, seeds, nuts, tofu and tempeh are all good sources of protein.

I hope the claim was based on more than "The Union won". Otherwise we can say:

The Union soldiers wore blue. The Confederate soldiers wore grey. The Union won. The conclusion is obvious.