Can humans eat plants safely? Yes, with caveats. Plant based foods must be prepared properly and eaten with care. Raw acorns rotted teeth of paleolithic people, but preparation rendered them safe for consumption by many Native American tribes. Cassava prep is another example Beans and lentils should be soaked ("sprouted") 12 hours before cooking, grains and nuts should be sprouted, unsprouted grain flours should be bran free (no phytic acid) and fermented (multi-rise, sourdough). Beware of goitrogens, solanine and oxalates in vegetables, & much more