From what I have read, lecithin has been used medically since before I was born to dissolve gallstones and in more recent times a cure for MS. The brain being mostly lecithin and the blood flows on a lecithin highway, etc., etc. I see it as an important supplement to the normal diet. Those with a natural diet would not need it.
Like dissolves like and the body must be able to take up the plant lecithin and use it possible to make human lecithin, either way, it is cheap and is used allot in commerical cooking, because with out lecithin, many foods could not be sold. I can safely state most people are lecithin deficient because commerical food used the lecithin as bait for their junk foods on purpose.