The brain is 75% water. Even 1-2% dehydration impairs memory, focus, and decisions. Lead, PFAS, and nitrates cross the blood-brain barrier. Harvard research links water quality to cognitive performance.
The read Glen’s take, in his words
The brain is 75% water. A two percent drop in hydration produces measurable decline in memory, focus, and decision-making — Harvard research confirmed this. But the quality of water matters as much as the quantity. Lead, PFAS, and nitrates all cross the blood-brain barrier. What you drink affects how well you think. That connection changed everything about how I approached my own hydration. This chapter connects the neuroscience to the contamination story. It's one of the most important chapters in the book.