Everything we ingest and apply to our body is a "drug" in some form or fashion. Our entire mental state is a direct result of the combination of different elements that effect our mind in so many ways. We often do not realize who we are or how our mind works the way it was designed because we have never been clean and free from all the mind-altering substances. The exception is if we were breastfed as infants but then again we are drinking the milk from our mothers and consuming whatever they have ingested. When you eliminate all the negative elements from your body and replace it with the world's most powerful and nutritious foods; everything in your brain will work differently than it has ever before.
Just imagine how it will work by just eliminating sugar, caffeine and alcohol...let alone, other contaminants.