sdyer@bbncc5.UUCP (Steve Dyer) (10/22/85)
I was wondering if an MD or renal physiologist could comment on the
effect of carbonated beverages on the pH of urine. Are such beverages
considered a good source of bicarbonate ion? If so, would they be expected
to increase the pH of the urine?
--
/Steve Dyer
{harvard,seismo}!bbnccv!bbncc5!sdyer
sdyer@bbncc5.ARPAwerner@aecom.UUCP (Craig Werner) (10/24/85)
> I was wondering if an MD or renal physiologist could comment on the > effect of carbonated beverages on the pH of urine. Are such beverages > considered a good source of bicarbonate ion? If so, would they be expected > to increase the pH of the urine? > -- > /Steve Dyer [I'm not an MD (*), but I play one on CRT] (* yet) Something to this effect was asked once before (the actual question was whether the Cabonation of beverages adds to the calories). Bicarbonate ion is primarily the result of the combination of C02 (Carbon Dioxide and Water). That's how the drinks are fizzed - a little bubbly C02. That is also how all the air you breath out is carried in the Venous blood. About the ONLY way known to increase blood Bicarbonate levels is to stop breathing. Eating half a box of baking soda might do it too. However, eating half a box of baking soda will raise URINE bicarbonate by the simple rule of Bicarb in = Bicarb out (a simple correlary of the First Rule of Renal physiology - you don't consume beer, you borrow it.) About the original question, Carbonated beverages are not a good source of bicarbonate. As soon as the Bicarb hits the acid stomach, it turns into CO2 (a gas) and H20 and you belch it. Even if it got in, you would breath it out the lungs as quick as you drink it, which is not very quick for the total amount. Paradoxically, it might lower Urine bicarb concentrations because the extra 12 ounces of Soda will dilute the Urine, but so would 12 ounces of H2O. -- Craig Werner !philabs!aecom!werner "The end. 94. 95. The very, very, very end."
jak@mtgzz.UUCP (j.a.kushner) (10/24/85)
I am neither a n MD nor a renal physiologist, but I would venture to say that carbonated drinks have little, if any, effect on urinary pH. For the CO2 ingested to become HCO3-, in a reasonable amount of time, the presence of the enzyme carbonic anhydrase (CA). This enzyme catalyzes the following: H2O + CO2 --CA--> H2CO3 -->H+ + HCO3. Assuming that this were the case and the bicarb were absorbed from the gut, it would immediately be buffered by one of the many buffer systems in the blood. If it did upset the normal pH, the first compensation would be respiratory, where the HCO3- would undergo the reverse reaction to become CO2, and been exhaled. One of the major places that CA can be found is the red blood cell, which carries out this process normally between the lungs and the rest of the cells of the body. My guess is that the CO2 actually leaves from one end or the other before any considerable absorption.