Naturally occurring plant toxins, just as manmade pesticides, usually disrupt metabolic processes by blocking certain enzymes. Possible effects range from hallucinogenic to degenerative and mutagenic. Three major groups of natural food toxins are alkaloids, bioactive amines, and fungal toxins. Worth mentioning are also purines, salicylates, pyrrolizidine alkaloids and carrageenan. Fortunately, most of natural food pesticides are intended for much smaller predators, and don't pack enough of a punch to harm humans. However, prolonged use of little known herbal preparations and teas carries the risk of harming your health.