How long does it take for salt to digest?

Discussion in 'Biology & Genetics' started by ausguerila, Mar 10, 2017.

  1. ausguerila Registered Member

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    I noticed that my saliva was quite salty. How long does it take to digest salt to bring saliva back to a normal level?
     
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  3. exchemist Valued Senior Member

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    Salt (NaCl) is a simple ionic compound that easily dissolves in water and consequently in fluids within the body. It is not digested: it is just absorbed.

    If your body has excess salt it is excreted by the kidneys until you are back in balance. So your urine will become salty for a while.
     
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  5. ausguerila Registered Member

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    How long does this take on average?
     
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  7. DaveC426913 Valued Senior Member

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    It's not nearly as simple as that.

    Salt is not a discrete product in your body, like iron or copper. The body is driven by ions of salt: Calcium, Sodium and Potassium. Every cell and every muscle fibre uses these ions in various functions. Your body will retain and excrete salt as a normal part of its functions, and the "life" of any amount of salt ion within the body will be complex. You cannot separate salt from the metabolism of the body.

    To ask how long salt takes to be metabolized is like asking how long it takes for a TV to use a particular bit of electricity.
     
  8. exchemist Valued Senior Member

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    I could not find a clear answer to that, just a remark that it happens "rapidly", presumably within hours rather than days. However I think I have read that the ability to excrete surplus salt varies between individuals and that this is one reason for increased blood pressure (hypertension) in many, though not all, older people who have had a salty diet.
     
  9. DaveC426913 Valued Senior Member

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    I'm not sure if its relevant at all but, as part of a blood pressure regimen, I take a "water pill" (Hydrochlorothiozide) that causes me to excrete excess water from my system (lest it collect around my heart).

    I could set my watch by the lapsed time between talking the pill and having to whiz. It takes five hours, every time.
     
  10. rpenner Fully Wired Staff Member

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    This seems more like a question of why you perceive your salvia to be "quite salty" since salt taste buds are sensitive to the ions of Sodium and other metals and saliva is normally less salty than blood plasma. Since the threshold for salty sensation is for Na+ 3.12 mmol/liter (and similar for K+) while the composition of normal saliva ranges for Na+ 2-20 mmol/liter and for K+ 10-36 mmol/liter, saliva IS salty. Perhaps you suffer from dry mouth so notice it especially at times when your saliva levels are closer to normal? Perhaps you have oral bleeding and are tasting the much saltier blood plasma?

    If this is a persistent thing, you could quantify it scientifically by taste-testing sips of dilute table salt solutions. Just be sure to spit out the salt water rather than swallow it as you likely don't need more.

    5.69 g NaCl = 1 level teaspoon of table salt
    58.44 g NaCl = 1000 mmol Na+ when dissolved
    1 liter = 4.22675 cups

    1/4 tsp table salt dissolved in 1 liter lukewarm water ≈ 24.3 mmol/liter Na+
    1/4 tsp table salt dissolved in 3 cups lukewarm water ≈ 34.3 mmol/liter Na+

    If this is the taste of "quite salty" then you are still well within the normal range for saliva.

    https://en.wikipedia.org/wiki/Saliva#Contents
    https://en.wikipedia.org/wiki/Taste#Saltiness
    Food Chemistry (Page 38/1070) H. D. Belitz, Werner Grosch, Peter Schieberle. Springer, 2009.
     
  11. ausguerila Registered Member

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    4
    So how long does it take to digest salt to bring saliva back to a normal level?
     
  12. timojin Valued Senior Member

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    depends on how much water you intake to piss the excess of the salt in your system
    Or you can get some heavy Na 22 which have a half life 15 hours, monitor it in your urine and you tell us
     
    Last edited: Mar 14, 2017
  13. rpenner Fully Wired Staff Member

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    That is literally impossible. Saliva has less salt than your blood needs to have in it for you to live. And what little salt it has, you don't lose since saliva is not expectorated in polite company.
     

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