Bladder stones, catheters, spinal cord injuries...and diet - Specialist Nutrition Rehab


27 Jan 2021

Bladder stones, catheters, spinal cord injuries…and diet


Bladder stones (also called bladder calculi or urolithiasis) and other types of bladder problems, are common after spinal cord injury.  Thirty-six percent of patients with indwelling catheters have been found to develop bladder stones within 8 years and this can lead to catheter blockages and/or autonomic dysreflexia.1


There are four main causes of bladder stones:

1. Incomplete bladder emptying – this can be from neurogenic bladder disorder or benign prostatic hyperplasia.2

2. Having an indwelling catheter or a foreign body in the bladder.2

3. A kidney stone passing into the bladder.2

4. Recurrent urinary tract infections with urease-producing organisms.3,4


In clients who are catheterised, the body treats a catheter like a foreign body and bacteria attach to it, covering it in a biofilm which also incorporates urinary crystals like struvite and calcium phosphate.1, 3  Certain urease-producing bacteria in the bladder speed up this process because they make the urine more alkaline which promotes certain crystals/salts to form.1   These crystalline deposits can encrust and block the catheter.  When the catheter is changed, sometimes debris, stone fragments or even pieces of a foley catheter can be left behind in the bladder which then promotes further stone formation.1, 2

There are several different types of bladder stones, all with different compositions – the most common are uric acid, calcium oxalate, calcium phosphate, ammonium urate, cystine and calcium-ammonium-magnesium phosphate (struvite).2  Each type of stone is created by a different set of factors and conditions and so the treatment strategy will vary greatly depending on what is causing the problem.


What is the role of diet in bladder stones?

What you eat can affect the pH (acidity) if your urine.  Uric acid stones are more common when urinary pH is more acidic, while calcium phosphate stones are more common when urinary pH is more alkaline.2 Altering the pH of the urine through medication, bladder washes or dietary changes, can cause stones to reduce or dissolve.2


Top tips for clients with debris and stones in the bladder:(5)

1. Refer them to a urologist – this is to investigate the cause.

2. Get the stones analysed if possible – then you will know exactly what is causing the problem and how to treat it.

3. Check the pH of the urine –  if you can’t get a stone analysed, this will give you a pretty strong clue as to the type of stone which is likely forming. Ideally check fresh urine four times in a day.

4. Encourage clients to drink 2.5 – 3 litres of fluid per day (or otherwise drink until their urine is clear) –  this dilutes the minerals and debris in the urine.

5. Reduce their intake of animal protein –  animal protein increases uric acid in the urine, makes the urine more acidic (low pH), reduces citrate in the urine, increases oxalate in the urine and promotes the formation of various types of bladder stones. It also causes more calcium to be excreted and increases the risk of calcium stones. Limit animal protein to a maximum of 0.8-1g/kg body weight.

6. Increase their intake of vegetables – a high vegetable and fruit intake, or a vegetarian diet, can make the urine more alkaline (increases pH).  These foods are also a good source of potassium which can also be helpful.

7. Ensure adequate (but not excessive) calcium – 1000-1200mg of calcium from food sources is recommended. Restricting calcium isn’t helpful.

8. Reduce their intake of salt – too much salt causes the body to excrete calcium, increases the risk of sodium urate crystal formation and reduces citrate in the urine.

9. Specifically for people with calcium oxalate stones:

  • Avoid foods high in oxalate such as rhubarb, spinach and black tea.
  • Avoid an excessive intake of vitamin C (over 1 gram).
  • Avoid foods high in purines such as beer, seafood and organ meat.


What about cranberries and apple cider vinegar?

Cranberry juice/supplements are often thought to be helpful for the bladder.  Unfortunately, they are not effective at preventing or treating UTI’s in people with spinal cord injuries (6, 7) and can actually increase the risk of calcium oxalate and uric acid stone formation.8

There is very little research around using apple cider vinegar for preventing or treating bladder or kidney stones.  One animal study found that vinegar reduces calcium oxalate kidney stones because it increases urinary citrate and reduces urinary calcium excretion.9 Clearly much more research is needed.

To refer a client with a spinal cord injury, brain injury or orthopaedic injury for dietetic assessment, please contact Specialist Nutrition Rehab at 0121 384 7087 or  For more articles like this straight to your inbox, please sign up for our newsletter below.

Newsletter Sign Up

/ /


/ /


Specialist Nutrition Rehab
West Midlands
B24 0PL


07787 603 863

0121 384 7087

Follow me

Send us a message

/ /

Send any questions or comments using the form below and we will get back to you as soon as possible.

    Check out our privacy policy here