I'm no expert on the subject (and won't discuss rumors that the science behind "B17" is faked, as I haven't taken the time to research it), but advocates of B17 tend to assume that "nature" or God designed the nutritional content of most to all plants with humans in mind, wherefore B17, being natural, is thought to be safe if consumed as a whole food (admittedly, there are additional arguments in favor of B17-not trying to create a straw man here). However, most plants' seeds have antinutrients intended to weaken those animals that consume them as a defense mechanism. The most obvious consequence of this fact is that grain-based diets are extremely unhealthy, of course.