Assume the following for the sake of the question:
1) I select a legume with relatively low phytate and lectin contents.
2) It has relatively low glycemic load, or I will limit my portions accordingly if it does not.
3) The legume is not prone to molding and the resulting fungus toxins (unlike peanuts for example).
4) I soak it in a near optimal way for several days, decreasing lectins some, drastically decreasing phytates, and also decreasing indigestible polysaccharide (e.g. raffinose) content considerably.
5) I pressure cook it for a bit longer than recommended, eliminating virtually all lectins and phytates.
According to the Paleo Way, are saponins the last obstacle to me enjoying a plate of these delicious beans?
It appears to me that nothing will be an obstacle to keep you from "enjoying a plate of these delicious beans..."! I find most starchy foods are simply a vector for the flavorful goodies I top it with.
If anyone must eat lentils - one must try the ones available at several Indian grocery stores marked "Hulled and split". All lentils are available as a whole grain/seed or as hulled and split which is after removing the outer shell and then split into two. The hulled and split ones have a lot of the toxins in the outer shell mechanically removed.
I suspect that one of the main motivations, for most people, for avoiding legumes is simply because they're very carbohydrate rich. There are no legumes that I'd consider as having 'relatively low glycemic load' since 100g of lentils (not much), will give you 50g+ of carbohydrate. The fact that they have a relatively low glycemic index, I wouldn't view as particularly significant, since you're still going to have to absorb the glucose some time, however much fibre is slowing down its digestion. All in all it seems a bit of a waste of one's days carbohydrate, given how much fruit/vegetable you could consume within the same limit.
If you're a high-carb paleo though, eating a lot of starchy tubers, I guess it would be much harder to justify the distinction. My own suspicion is that anything that requires such elaborate preparation is likely, even when tolerated, to be sub-optimal. (To steal Kurt Harris' formula).
Incidentally, before going paleo I used to live on lentils/chickpeas. It didn't do me any visible harm (apart from losing about 2 stone in a matter of months- not a good thing), but neither did living on mostly raw wheatgerm and soy milk, which I've also practised.
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