I would agree with this, except that there are actually some good long term suggestion that if you put large groups people on nearly/entirely only potatoes you

I would agree with this, except that there are actually some good long term suggestion that if you put large groups people on nearly/entirely only potatoes you do end up with remarkably healthy people. This is noted in, of all things, Adam Smiths the Wealth of Nations when he compares the diet of the poor in England (mostly wheat), in Scotland (Barley?) and, of course, Ireland (Potatoes). He notes that, of these groups, it is not the relatively well-of poor in England who are the healthiests, but the poorest of the all, the Irish. The poor in Ireland would not be able to afford more than the cheapest food, which would be whatever greens were in season and potatoes.