And vegetarians struggle quite a bit with getting proper dietary nutrition, not just with iron, but also Vitamin B12, Zinc, Omega-3 fatty acids, Vitamin D, Calcium, Protein and Riboflavin. So it is not quite just "simply" adjust your diet you lazy meat eater.
All of those listed able to be met easily by plant based sources with a well balanced diet.
And it's not like the average meat American is eating a healthy diet. I would be shocked if the standard American diet actually met all recommended nutritional intakes.
B12 is only in significant amounts of meat because it is heavily supplemented and present in the soil, today's clean produce strips most of those bacteria from the food supply.
The solution is really simple, though: eat less meat. We don't need meat every day. Once or twice a week is more than enough, and if everybody did that, it would greatly reduce this problem.
I checked Wikipedia though, and it agrees with you, which makes me wonder even more why I've heard this exact same experience from several unconnected vegetarians.
Although I do wonder, if we're wrong about B12 only coming from animals, is it possible that we, or possible even Dutch physicians, are under-informed about our options?
I'm a vegetarian (yes, not a vegan yet) living in India and I'm not deficient in any of these. Also, never have been.
e.g. take the case of protein, I eat pulses almost daily (and a variety of) with rice, never felt I have less protein than required.
Vit B12 - you can get from fermented foods like Idli etc. Also, from the water soaked overnight in rice (actually rice is soaked in water).
Vegetarianism had been practised in India since time immemorial. One can say the food has been perfected here to stay healthy.
Vegetarians are self-selected. We can have reasonably high confidence it would be fine, but we can't be sure, and some people literally will not be able to tolerate it.
> I am not aware of have any health problems that are most efficiently solved by adding meat.
Depends how you define "efficient". There are plenty of nutrients that are most concentrated in meat, such that small portions of meat can replace the need to consume large portions of plant matter.
It runs in my family. My poor mother is so bad that she has had to have a couple of blood transfusions because nothing else would bring her back from a bad state when she got there (the alternative being just lie down and die). Supplementation hasn’t helped her many times†. They also rarely eat red meat.
Here’s hoping I or my sister don’t end up the same way. My sister has already devolved to anemic and has had her own complications with that.
† edit: Rereading this it sounds confusing. I meant that supplementation has not helped her either prevent or recover from those cases until after the transfusion where her doctor stressed diet.