Following an 100% vegan diet in a healthy way requires more care in choosing some appropriate nutritional supplements and in planning what you eat than for any other kind of diet.

I am vegan and I enjoy it, but I would not recommend this for everyone, because there is no doubt that it would be too tedious for most people, who prefer to eat in a more spontaneous way, without needing to ponder whether what they happen to eat has an adequate nutritional content, taking into account what else they had eaten that day.

But knowing how certain African cultures learned to neutralize Cassava, and that knowledge passed through generations without knowing the reason why, I learned to not fully dismiss these kinds of knowledge...

Dark leafy greens are not "quality sources of calcium". One would need to eat several kilograms per day. No human does that. The quantity that needs to be eaten is greater than it could seem from the elemental analysis, because a part of the calcium will be lost during cooking and another part will remain bound in insoluble compounds that will not be absorbed in the intestine. Moreover, eating many kilograms per day of dark leafy greens is guaranteed to cause health problems due to oxalic acid and other substances that are present in excess.

All the studies that I have seen have shown that the vegans who do not take calcium supplements have significantly less amounts of calcium in the body than non-vegans and are more prone to osteoporosis.

This kind of false information about plants that are "quality sources" of substances that are really deficient in all plants is very dangerous for vegans. Any vegan must take up to a dozen supplements to maintain optimal health and those who are not aware of this develop sooner or later various health problems and many go back to a traditional diet, without understanding what they did wrong.

Your link uses the silly "cup" unit of measure from which it is hard to assess which is the real calcium content.

The right way to show the content of a nutrient in some food is to show how many kilograms or pounds you must eat daily to provide enough of that nutrient.

In the case of calcium the best case that I have seen for various vegetables is that you would need to eat at least 1 kilogram per day, based on the elemental analysis.

However this is far too optimistic, because when cooking the vegetables a part of the calcium may be lost and another part will be bound in insoluble compounds and it will not be absorbed in the intestine after eating.

So a more realistic estimation is that even for the vegetables with the highest content of calcium you might need to eat at least 2 or 3 kg per day.

For nuts and legumes it is impossible to approach even 1 kg of daily intake, as that would include too much energy in starch or fat.

So only leafy vegetables would avoid gaining weight, but eating kilograms per day would be not only unpleasant, but also harmful.

I happen to be a vegan, so I have studied carefully my alternatives and the best for me is to add some calcium phosphate powder to my food, together with the table salt. I use phosphate and not another calcium salt, because even if all seeds and nuts, including all legumes, have large amounts of phosphorus, most of it is contained in phytic acid, which is harmful, so I use preparation methods that remove much of the phytic acid, but they also remove most of the phosphorus, so I compensate that by adding the calcium as calcium phosphate.

Biolavailability

Though I don't see the point of quibbling here. My point only gets stronger and stronger as I add in more foods and calories, even packaged grain foods that are incidentally fortified with iron.

I'm with you 100% on this. But vegans needing a dozen supplements for optimal health is a different claim than bad internet nutrition advice leading people astray from optimal health.

If you personally feel like you need a dozen supplements even as an informed vegan, I would give you some resources or at least refer you to a dietitian.

A controversial point of my own to some people is that vegans should and often must embrace "processed foods" to hit optimal protein goals. Foods like seitan, textured vegetable protein, tofu, and ultra-processed vegan products have the highest protein density. Yet the fear of processed foods is vogue on social media, and there are plenty of green mommy vegan blogs that will list a cup of lentils as a protein heavy-hitter yet never mention TVP, seitan, etc. There is also plenty of other vegan cringe online like the no-oil vegans who minimize dietary fat.

But that wouldn't mean you can't get sufficient protein on a vegan diet.

Social media and Youtube nutrition advice is horrible for everyone, I think. My own father has been convinced that butter is a superfood by Youtube quacks. They also convinced him to quit his blood pressure meds and that the carnivore diet is so healthy that you can dispose of any cautionary blood panel markers—they simply don't apply to you anymore.

I use gut feeling, but am mindful of stimulants in the diet, so I mega dose with supplements to get a better idea of what something is doing.

I can highlight the pitfills in the so called double blind placebo gold standard of scientific study on lab animals.

While table salt is supplemented by default with iodine almost everywhere, flour and milk are supplemented by default only in a few countries and I consider that this is a very good thing and that they should not have been supplemented by default anywhere.

This forced supplementation is stupid, because it will not achieve an appropriate daily intake, except for a few people who happen to eat a certain amount of floor and milk, while for all the others it will be either too much or too little.

The right way to help the poor is to subsidize the price of vitamins and essential minerals, not to waste them by adding them to a certain kind of food, so that everyone who eats something else will not get them.

And the argument that the government should supplement some food ingredients because people have become too stupid to eat what they should, is even more ridiculous. Even supposing that modern people have become more helpless than their ancestors, so they would not be able to identify or catch anything edible when left alone in a forest, that does not mean that they should not be able to at least have the survival skill of buying the right food from a supermarket.

If it is believed that most people are not capable even of doing that, then they should be educated instead of hoping that the solution is that the state should feed them with food ingredients whose composition they no longer understand.

There certainly are few things more important for any human to know, than how to choose what to eat, in order to not die and to remain healthy.

The majority of the people living in developed countries eat 1.4 g/kg of proteins per day or more.

Eating 1.2 to 1.3 g/kg of proteins per day from a balanced diet restricted to vegetable food to which no special methods for separating the proteins from starch or fat are applied, results in over 3000 kcal per day.

If I eat more than around 1800 to 1900 kcal per day, I gain weight very quickly.

Removing about 75% of the starch from my bread removes at least 1000 kcal per day, which brings the total to less than 2000 kcal.

I have experimented twice with eating only around 0.75 g/kg of proteins per day, and after a few weeks the concentration of albumin in my blood has decreased (low albumin levels in blood can be noticed even without a blood analysis, because they cause swollen feet).

While this was a little lower than the old recommended value, it was close enough that bad effects were not expected. Now I always eat at least 1 g/kg of proteins per day, and up to 1.3 g/kg.

The only parts of plants that have high protein content are the seeds. Excluding soy, the other seeds of legumes have at least a 3 to 4 times higher calorie content than corresponding to the protein content, while most cereals have at least a 6 to 8 times higher calorie content than their protein content.

When someone does heavy physical work, so 3000 kcal per day or more is OK, then yes, a diverse vegan diet without any special cooking methods is good enough.

On the other hand, for a sedentary life it is not possible to reduce the energy intake from vegan food to 2000 kcal/day or less, without some special protein extraction method.