Regarding mineral absorption, it is true that soy and other legumes (beans) contain a class of chemicals (phytates) that reduce our absorption of certain minerals including iron, zinc, calcium and manganese (divalent cations).
While this ‘downside’ is legit, I don’t see it as a reason to avoid soy (and other legumes).
Here is why:
- The decreased absorption of the few relevant minerals can easily be overcome by eating more of them. Meeting all your needs is not an issue even if your diet contains phytates assuming it is mostly nutritionally sense. I overshoot many of my target RDAs without trying.
- Phytates may also have health benefits. Read a balanced perspective here
Phytates and phytic acid. Here's what you need to know. | Precision Nutrition
Phytic acid - the storage form of phosphorus - is often considered an anti-nutrient because it binds minerals in the…
As for lectins, I’m just digging into this topic. My sense is that the concerns are overblown, given the long history of health in countries that embrace legumes – though often processing them in ways that reduces lectin content.
My initial scouting on this topic has me concluding that moderation is a good way to go (surprise surprise!).
Below I share a well researched article from a reliable source. It provides a look at pros and cons and provides an explanation for the case study regarding problematic red kidney beans. It also supports what your link said about the benefits of fermentation (with no products attached!)
All about lectins: Here's what you need to know | Precision Nutrition
Bean sprouts aren't just for hippies. There's method in that madness -- reducing the harmful effects of lectins,…
Overall, my sense is that legumes are still a multi-dimensional win (especially compared to animal protein sources) despite any minor negatives. There is no perfect food – I bet even breast milk has issues one could cast aspersions on! It strikes me as foolish to throw out the baby with the bathwater.
I hope this helps. I’ve updated the article to cover some of this discussion.