I think most veg*ns in countries where meat consumption is high, such as the UK where I live, are accustomed to being asked "Where do you get your protein?" but it's widely accepted that even vegan diets provide plenty of protein, though sources of lysine may need to be consciously included.
Nonetheless, whenever I enter a health food shop online or off, I find loads of vegan protein supplement products. In and out of such contexts, I often feel like advertisers are urging me to load up on protein, while cutting down on fat and carbs.
However, I frequently get emails from vegan organisations with statistics about USians (in particular - I'm sure the same is true in my country) eating much more protein than they need (but nowhere near enough fibre, and falling well short of recommendations on eating fruit and vegetables). These statistics would be more useful to me if I could explain why eating too much protein should be discouraged.
I think eating more protein than the optimum quantity for good health is bad in terms of resources, carbon footprint, equity and so on, but I also suspect their are health reasons to avoid eating excessive protein.
What are the disadvantages of consuming more protein than is necessary for good health?