There is no communist country on this planet, all examples you are thinking about are countries which have achieved socialism to some degree. Most of them are ruled by parties which want to achieve communism eventually (and thus call themselves communist parties). Nobody is claiming that those countries have achieved communism.
And also, working people in those countries have it much better than their capitalist neighbours. There is a very clear difference if you look at speed of quality of life changes, HDI improvements, wealth distribution, or minority rights.
Ok, name me a nutrient and I'll give you either a plant-based source of it or evidence that your body or gut biome produces it itself
And yeah, I agree, if you want to have a healthy diet you need to read up on dietology and/or visit a dietologist. But this has nothing to do with veganism, omnivores need to do it too.