this subject is so controversial i cant get a solid explanation. i am retrying an attempt to find better advice on the subject of continuing unorthodox methods that are controversial if they are truly of benefit to the individuals practice. (even if they may commonly be detrimental to others.)
Given that the fifth precept specifically refers to substances that cause "intoxication and carelessness", such a hypothetical substance would of course not violate it, no.
Food substances like Water, Carbohydrates, Fats, Sugar, Protein, Minerals, Vitamins etc. don't violate the 5th precept. They actually nourish the body, if taken in appropriate quantities. That is helpful for the development of the mind as well. Is there anything specific you are referring to?
Such a substance already does exist, it is called Camellia sinensis also known as ... regular tea! This traditional drink of Zen-Buddhist monks stimulates the mind and enhances one's ability to stay mindful, without causing intoxication or carelessness.
The biographical tradition is littered with apocryphal tales about Bodhidharma's life and circumstances. In one version of the story, he is said to have fallen asleep seven years into his nine years of wall-gazing. Becoming angry with himself, he cut off his eyelids to prevent it from happening again. According to the legend, as his eyelids hit the floor the first tea plants sprang up; and thereafter tea would provide a stimulant to help keep students of Chán awake during meditation. (Wikipedia)