How Staying Hydrated Boosts Cognitive Function

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How Staying Hydrated Boosts Cognitive Function

Water is vital for the human body. Every organism requires water to survive and function properly. With water being involved in many biological activities inside the body, it is the fact that dehydration is harmful to multiple functions in the body, including cognitive function. This article will discuss how dehydration affects cognitive function and how to stay hydrated for better health.


The function of water in the body

Water accounts for 60 percent of the body weight of an adult male. The human body can survive one to two months without food but only a few days without water. With just those few pieces of information, it is obvious how crucial water is for survival. 

  • Water is a solvent. 

That means solutes such as sugar or salt can dissolve in water. The polar nature of water allows it to surround other charged molecules and disperse them. That results in opportunities for numerous chemical reactions to occur.

  • It helps with transportation in the body.

Blood transports oxygen and nutrients to every cell in the body. It also delivers carbon dioxide and waste, such as urea and ketones, to specific organs to excrete them from the body. Hormones and other substances are also carried by blood throughout the body. Blood is 90 percent water, which explains how important water is in maintaining the transport of substances inside the human body.

  • It makes chemical reactions possible.

A hydrolysis reaction is a chemical reaction that breaks down large molecules with the involvement of water molecules. One example is when one molecule of maltose is broken down into two molecules of glucose. This allows for more chemical reactions to occur. In contrast to hydrolysis, a condensation reaction is when water is removed to join two or more molecules into a larger molecule.

  • Water helps maintain the acid-base balance in the body.

The acid-base balance is required inside our body to create an ideal environment for chemical reactions to occur. Most reactions function proficiently in a slightly basic solution. Disturbing this balance will prevent the chemical reactions from proceeding efficiently. Thus, health problems will be more likely to arise. Water is a medium for the chemical reactions that prevent changes in the pH, which will maintain the acid-base balance. If water is not adequately consumed, the acidity inside the body is likely to rise. The body always produces stomach acid whenever we eat to digest food. Hence, a limited amount of water will lead to a disturbance of acid-base balance, which is dangerous for our health.

Why is staying hydrated important for cognitive functions?

Cognitive function broadly describes various brain activities, including attention, memory, processing speed, and executive functions. The brain is undoubtedly the most important organ in our body as it coordinates and controls other organs. The cognitive functions of the brain allow us to think, remember, and react to our surroundings. 

Considering the functions of the brain in the body, it requires the most energy inside the body. Hence, chemical reactions required for the brain to function are definitely numerous. Discussing the roles of water above, it is obvious that many chemical reactions cannot take place properly without water, as solvent and acid-base balance are crucial for the reactions to occur. 

In addition, water dehydration limits the transport of substances, including hormones. The pituitary gland located at the base of the brain is called the master gland, as it regulates the other glands to release hormones. Due to dehydration, hormones are not delivered properly, and that results in multiple errors in cognitive functions. Some of these symptoms can be present, signaling dehydration:

  • Poor concentration
  • Slow reactions
  • Short-term memory problems
  • Mood changes

One study has shown a great reduction in cognitive performance over a 2-year period when hydration is decreased. Even with mild dehydration, the cognitive functions also experience a great reduction in working memory and increased anxiety and fatigue. Numerous studies have been conducted, and they mostly conclude that poor hydration is associated with reduced cognitive functions. Thus, water must be consumed adequately every day to maintain good health. A great way to rehydrate is by consuming 1 liter to 3 liters, an ideal range of fluid from water intake and food combined. More ways to rehydrate can include sports drinks, milk, fruit, and vegetables. This study showed that at least 500 ml of fluid should be consumed daily to prevent dehydration. However, consuming 1 or 3 liters of fluids is recommended to maintain a healthy body and improve cognitive functions.  


Water is undoubtedly vital for our survival. Considering its variety of functions in the body, lacking water can result in impaired cognitive functions. As cognitive performance is negatively affected, our overall physical and mental health will be harmed. Consuming 1 to 3 liters of fluid from water intake and food sources is ideal for proper cognitive performance. With adequate water, the most crucial nutrient, we can ensure our health is in good condition and our cognitive functions are optimized.       


(1). Nutrition: Science and Applications, 3rd Canadian Edition.,+3rd+Canadian+Edition-p-9781119614654

(2). Water intake, hydration status, and 2-year changes in cognitive performance

(3). Mild dehydration impairs cognitive performance and mood of men

(4). How much water do we really need to drink?

About the Author

Jared Levenson is a former binge eating wrestler turned Zen Buddhist Monk, Internal Family Systems counselor and nutrition wellness coach. He's helped hundreds of people through universal meal principles and internal family systems to make peace with food, stop binge eating, and find true health and wholeness.


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