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Caffeine (cont.)

Medical Editor:

How much fluid do we need?

Anyone who has ever been on a diet will tell you that you are supposed to drink at least 8 cups of water a day. Everyone knows this, but finding the evidence to support it is another story. In 2004, the Food and Nutrition Board established recommendations on the intake of water. The recommendations were set based on the necessary amount needed to maintain health and reduce chronic disease risk:

  • The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide.
  • The report did not specify exact requirements for water but set general recommendations for women at approximately 2.7 L (91 oz) of total water (from all beverages and foods) each day and men at an average of approximately 3.7 L (125 oz daily) of total water.
  • The panel did not set an upper level for water.
  • About 80% of people's total water intake comes from drinking water and beverages (including caffeinated beverages), and the other 20% is derived from food.
  • Prolonged physical activity and heat exposure will increase water losses and therefore may raise daily fluid needs, although it is important to note that excessive amounts of fluid can be life threatening. Acute water toxicity has been reported due to rapid consumption of large quantities of fluids that greatly exceeded the kidney's maximal excretion rate of approximately 0.7 to 1.0 L/hour.

The report allows all fluids to be counted into your total intake, so people began eliminating water from their diets in favor of other liquids. However, the recommendations were not intended to reduce water consumption. Water should be your primary source of fluid. Our bodies are made up of over 60% water, not coffee, tea, juice, or soda. Caffeine is a treat that will have health consequences when consumed in excessive amounts and is not safe for everyone. Set limits on the treats that you allow yourself, and be sure to give your body what it needs in adequate amounts. Too much of anything is just too much for our bodies to handle.

Medically reviewed by Martin E Zipser, MD; American Board of Surgery


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Last Editorial Review: 2/18/2015


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