03-12-2012, 11:03 PM
Mayo Clinic on coffee:
"Researchers used to believe that caffeinated drinks had a diuretic effect. This means that you would urinate more after drinking them, which could increase your risk of becoming dehydrated. Recent research shows that this is not true and that caffeine has a diuretic effect only if you consume large amounts of it — more than 500 to 600 milligrams (the equivalent of 5 to 7 cups of coffee) a day."
http://www.mayoclinic.com/health/caffein...ks/AN01661
Also, under some circumstances sugars can cause issues also, especially in higher amounts:
"Osmotic diuretics
Compounds such as mannitol are filtered in the glomerulus, but cannot be reabsorbed. Their presence leads to an increase in the osmolarity of the filtrate. To maintain osmotic balance, water is retained in the urine.
Glucose, like mannitol, is a sugar that can behave as an osmotic diuretic. Unlike mannitol, glucose is commonly found in the blood. However, in certain conditions such as diabetes mellitus, the concentration of glucose in the blood (hyperglycemia) exceeds the maximum reabsorption capacity of the kidney. When this happens, glucose remains in the filtrate, leading to the osmotic retention of water in the urine. Glucosuria causes a loss of hypotonic water and Na+ leading to a hypertonic state with signs of volume depletion such as: dry mucosa, hypotension, tachycardia, and decreased turgor of the skin. Use of some drugs, especially stimulants may also increase blood glucose and thus increase urination."
http://en.wikipedia.org/wiki/Diuretic
"Researchers used to believe that caffeinated drinks had a diuretic effect. This means that you would urinate more after drinking them, which could increase your risk of becoming dehydrated. Recent research shows that this is not true and that caffeine has a diuretic effect only if you consume large amounts of it — more than 500 to 600 milligrams (the equivalent of 5 to 7 cups of coffee) a day."
http://www.mayoclinic.com/health/caffein...ks/AN01661
Also, under some circumstances sugars can cause issues also, especially in higher amounts:
"Osmotic diuretics
Compounds such as mannitol are filtered in the glomerulus, but cannot be reabsorbed. Their presence leads to an increase in the osmolarity of the filtrate. To maintain osmotic balance, water is retained in the urine.
Glucose, like mannitol, is a sugar that can behave as an osmotic diuretic. Unlike mannitol, glucose is commonly found in the blood. However, in certain conditions such as diabetes mellitus, the concentration of glucose in the blood (hyperglycemia) exceeds the maximum reabsorption capacity of the kidney. When this happens, glucose remains in the filtrate, leading to the osmotic retention of water in the urine. Glucosuria causes a loss of hypotonic water and Na+ leading to a hypertonic state with signs of volume depletion such as: dry mucosa, hypotension, tachycardia, and decreased turgor of the skin. Use of some drugs, especially stimulants may also increase blood glucose and thus increase urination."
http://en.wikipedia.org/wiki/Diuretic