Question: Is it useful to measure urine pH?
The urine pH is telling you the acid burden that your body has been subjected to. It's telling you, you can make an inference about the compensations that your body has had to engage in. You can also make an inference about the limitations of your body in compensating for that because even your urine pH should be buffered. It's not the case that you put a little bit of acid in the urine and then boom your pH is going to go down. It's the case that your body has a whole bunch of systems to buffer even the urine pH as you excrete acids from your body.
The system is, like in your blood, the tiniest, tiniest change in your pH is immediately going to set in motion a change in your breathing rate that is going to cause you to either increase or decrease the exhalation of carbon dioxide in order to adjust the pH of the blood. Then there's going to be a longer-term compensation where you're going to take some of those acids and pee them out. When you pee them out, your kidney is going to buffer those acids in the way of preserving the urine pH.
If your urine pH goes down from 6.5 to 5.5, it tells you that your urine pH is like ten times more acidic, but it doesn't tell you that your blood is ten times more acidic. The critics of using urine pH will point that out. But what it does tell you is that your body has been subjected to a rather enormous acid burden, number one; and number two, that you're even starting to overwhelm your kidney's ability to buffer the urine and prevent the pH of the urine from changing. And so it does tell you about the stress put on the system.
A high potassium intake would be the number one thing that would acutely affect it apart from taking the bicarbonate. By the way, always take bicarbonate on an empty stomach away from food.
This Q&A can also be found as part of a much longer episode, here: https://chrismasterjohnphd.com/podcast/2019/09/06/ask-anything-nutrition-march-8-2019
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