A new study, published in PLOS One, found that there is no evidence of dehydration associated with moderate daily coffee consumption.  It is often suggested that coffee causes dehydration and its consumption should be avoided or significantly reduced to maintain fluid balance.  The current study was designed to directly compare the effects of coffee consumption against water ingestion across a range of validated hydration assessment techniques.  Researchers found that coffee, when consumed in moderation by caffeine habituated males provides similar hydrating qualities to water.

According to the Huffington Post, the study was actually funded by the Institute for Scientific Information on Coffee (ISIC).  Some coffee companies, including Nestle and Illy, are members of ISIC.  This indicates the possibility of a conflict of interest or desire to have a certain result.  However, ISIC is a non-profit organization and did not have a role in the study design or analysis, which minimizes the risk of a conflict of interest skewing the results.

Maintenance of fluid balance is essential to sustain human life. Water intake balances fluid losses to achieve adequate hydration of bodily tissues.  Although there are widespread guidelines in scientific literature and media for achieving optimal hydration status and about the effects that various caffeinated beverages may have on fluid balance, there is no clear consensus about how much fluid an individual should consume.

Well-known guidelines usually dictate and 8×8 rule, or eight glasses of water that are eight ounces each.  However, according to the Dr. Oz Show website, these guidelines are no longer applicable and there is no guideline applicable to every person.  In general, women should consume 91 ounces per day and men should consume 125 ounces.  However, certain foods add to fluid consumption, daily activities can increase the required consumption, and some conditions and diseases can impair regulation of fluids or thirst indication.

The Mayo Clinic describes dehydration as when a person loses more fluids than he or she takes in, leaving the body with insufficient water to perform its normal functions.  Common causes of dehydration include intense diarrhea, vomiting, fever or excessive sweating. Not drinking enough water during hot weather or exercise also may cause dehydration. Anyone may become dehydrated, but young children, older adults and people with chronic illnesses are most at risk.

Symptoms of mild dehydration include dry, sticky mouth, tiredness, thirst, decreased urine output, dry skin, headache, constipation, and dizziness.  Severe dehydration symptoms include very dry mouth and skin, lack of sweating, little or no urination, urine produced is dark yellow or amber, shriveled skin that is dry and without elasticity, rapid breathing and heartbeat, and low blood pressure.  Severe dehydration is a medical emergency.