Hormesis (from Greek hórmēsis "rapid motion, eagerness," from ancient Greek hormáein "to set in motion, impel, urge on") is the term for generally favorable biological responses to low exposures to toxins and other stressors. A pollutant or toxin showing hormesis thus has the opposite effect in small doses as in large doses. A related concept is Mithridatism, which refers to the willful exposure to toxins in an attempt to develop immunity against them. Hormetics is the term proposed for the study and science of hormesis.
http://en.wikipedia.org/wiki/Hormesis
どうも胡散臭い言葉となっているホルミシスだが、微量（適量）の毒やストレスは健康に役立つ、という思想であり、ストレスに関しては、
・白い壁紙の部屋で、白いベッドの上でずっと寝ている
・一日３０分位走って、６時間ほど軽作業をする
・某外食チェーンで働く
どれが一番健康にいいか、みたいな雰囲気で捉えてもいいのかもしれない。
毒物は… ？
