Ask the Expert: How Does Hydration Impact Brain Function and Energy?

Ask the Expert: How Does Hydration Impact Brain Function and Energy?

Hydration has a major effect on brain function and energy levels. Studies show that even mild dehydration - 1-3% of body weight - can impair many aspects of brain function.

Our brains are 73% water according to the United States Geological Society. The brain needs that water to manufacture hormones (molecules produced by the endocrine system that send messages to help regulate body processes) and neurotransmitters that transmit signals from nerve cells to muscles, glands, or other nerves. Neurotransmitters regulate many necessary functions, including heart rate.

Joshua Thurman, M.D., explains: "When we become dehydrated, brain and body are unable to function optimally. The water we drink increases the flow of blood and oxygen to the brain to help it (and us) maintain our concentration and cognition, mood and emotions, and memory function."

Dehydration affects sodium and electrolyte levels in the body, which have also been linked to cognitive changes.

Dr. Thurman: "When the body loses water and it is not replaced, the concentration of electrolytes (minerals that help regulate and control the body's balance of fluids) in the blood and other body fluids increases. When the concentration of body fluids increases, it can actually pull water out of the brain by osmosis, which in this case refers to the movement of water to keep concentrations balanced. This imbalance is why the sense of thirst can feel so strong — thirst is the body's way of making sure that the balance of water and electrolytes is maintained in the proper range."

The upshot: To guarantee peak performance, mentally and physically, it's crucial to hydrate!


Dr. Joshua Thurman, MD is a board-certified nephrologist and Professor of Medicine specializing in renal medical diseases and hypertension at the University of Colorado School of Medicine. He received his medical degree from the University of Chicago Pritzker School of Medicine and his undergraduate degree from Harvard University. He has been in practice for more than 22 years.

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