People often ask me why they need to avoid "acidic" foods if they have interstitial cystitis. The answer isn't as clear cut as you may think, however. I believe what has happened over the years is that it is convenient to "explain" an IC diet to someone quickly by telling them to avoid acidic foods in order to protect a painful bladder.
That, however, is also part of the historical resistance of doctors and dietitians to accepting a diet for IC. People who have studied biochemistry and physiology know just what you said, "acid in doesn't equal acid out." (An acidic orange juice forms an alkaline metabolite when digested, and the acidic cranberry juice forms an acid metabolite. There are many more interactions here, but you get the point.)
It isn't all about acid/alkaline, however when it comes to an IC bladder. There are other reasons why a food bothers us.
One is an allergic or inflammatory type response that kicks up the degranulation of mast cells. This can even be caused by stress. (Maybe you or someone you know has gotten hives when they were under a lot of stress...that is the mast cells of the skin going haywire, just like can happen in the bladder.)
The second way a food can affect the bladder is as a chemical reaction on the nerves - think about caffeine and MSG - both stimulate bladder spasms or frequency.
The third way is related to the acid/alkaline theory but isn't as clear as we would like it to be. Nearly everyone's urine pH bounces around all day long. The BODY pH needs to be kept at a fairly constant level or, simply put, we would die. So there are feedback mechanisms in our bodies to prevent wide swings of BODY pH. One of those feedback mechanisms is the urinary tract system. The BODY is kept at equilibrium by expending acidic or alkaline properties often through the urine. (see http://www.rnceus.com/ua/uaph.html for more information.) So as you go through the day, depending on what you consume, if you are exercising, or are under stress, your body is very hard at work trying to keep that pH steady. As a result, the URINE pH bounces around, as I said a bit ago, in an effort to maintain a steady BODY pH.
Now, the next step in this thought process is to remember that most people have healthy bladders and are not even aware that this is happening. In our cases, however, we have wounds in our bladder - everywhere from tiny hemorrhages to full blown Hunner's ulcers. Do you see where I am going with this?
If you had a cut on your hand, would you put it in a bucket of lemon juice (an acid product)? NO way, right? BUT, you also wouldn't put that wounded hand into a bucket of bleach (an alkaline product). It would hurt also! Neither of those liquids would hurt a healthy hand in the short term, right?
The same goes for your bladder....if the pH of the urine is bouncing around all day and you have wounds in your bladder, you are going to know it!
So, the acid/alkaline situation doesn't explain everything, but it can explain some of our symptoms. The pH issue, however, is not as easily controlled as one might think, nor should we rely only on pH as a way to control our symptoms. Some of the MOST reactive foods are the allergic/inflammatory and neurostimulatory properties of foods.
Let me know if any of this doesn't make sense and I will try to reword it.
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