Not poisoned but starved

Gary Wenk speaks about "brain food" and the way that the shared ancestory of ourselves and plants makes components of our food most effective in affecting our bodies and minds. Amidst this:

No, he does not die, because his species and that of the creature on this foreign planet do not share an evolutionary past or a common ancestor. Although they may both be made of proteins formed from amino acids, their independent evolutionary paths should made it highly improbable that they use similar neurotransmitter molecules within their respective brains and bodies. Every spaceman from Flash Gordon to Captain Kirk to Luke Skywalker should feel safe walking around any planet (except their own) with impunity from animal and plant toxins. For this same reason, the intoxicating drinks and powerful medicines that always seem to be popular in these foreign worlds in science fiction movies would also have totally different effects, if any effects at all, on the brains of our plucky spaceman. Eating otherworldly foods might be the most disappointing and distressing experience of all: Even if they were filling and somehow tasted delicious, as products of utterly alien biochemistries they would probably prove devoid of nourishment for our Earthly bodies. Thus, starvation might be the greatest threat to any future explorers of alien biospheres. Unless, perhaps, they’d brought along a large supply of chocolate.