A bunch of 'plant steroid' molecules (like ecdysteroids are insect steroids) that are present in relatively high amounts in mustard; still nowhere near enough to get jacked off of mustard. Have not been shown to be effective in humans yet, remains an unexplored research field.
Brassinosteroids is most often used for
Brassinosteroids are a class of steroid compounds found in plants, used to regulate and induce plant growth. They share many similarities with human steroid hormones, but are generally at too low of a dose to exert effects in humans (on hormonal profiles) via food consumption.
They have been implicated in mouse models on skeletal muscle growth, and in some cell lines show promise at being anti-carcinogens (cancer protective).
There is not enough information for a recommend dosage at this time.