Preventing and relieving constipation

Conquering a taboo: let’s talk about constipation

Many people suffer from it, yet no one really wants to talk about it: dialysis patients often have problems with constipation due to dietary and fluid restrictions or medication. This should no longer be a matter of “what happens in the bathroom stays in the bathroom”. Find out what you can do to relieve digestion problems and how to add more fibre to your diet while adhering to medical recommendations.

Generally speaking, constipation is a change in bowel habits, but it comes in a variety of forms. Typically patients would describe constipation as having infrequent stools; more specifically, less than three times per week. Moreover, stools may be too hard, too small or too difficult to pass. Patients may also feel that their bowels are not empty or they frequently need to strain.

Constipation is a wide-spread problem to which many factors can contribute. In most patients’ cases, no single cause can be identified. However, having chronic kidney disease or being on dialysis makes it more likely that a patient will suffer from constipation. Due to the loss of kidney function and various other factors such as a lack of exercise, impaired fluid balance and a reduced dietary fibre intake,1 the gastrointestinal tract is often adversely affected. Amongst the consequences, constipation is the most frequent symptom. Medications prescribed which relates to kidney diseases, such as iron medication (mainly pills), phosphorus-binding medicines, or potassium binding resins, can sometimes cause digestive problems, too.1

The diagnosis is the first step towards getting better

Constipation usually can be diagnosed based on your symptoms and a physical examination. You will likely need a rectal examination, and in some situations, your doctor will order further testing like blood tests, x-rays, an intestinal endoscopy or more specialised testing. The endoscopy will examine only the large intestine (sigmoidoscopy) or both the large and parts of the small intestine (colonoscopy). Don’t forget to mention any underlying diseases and medications you take when your doctor asks for history. This might include questions concerning, for example, a family history of colon cancer, blood in the stool, unexplained weight loss or recent changes in bowel habit.

Most people treat constipation themselves. Don’t take constipation lightly, though. You should definitely speak to your doctor if constipation is a recent change from your usual pattern, lasts longer than two weeks, is severe or you have other symptoms, such as blood in your stool or on the toilet paper, unexplained weight loss or fevers. The appropriate treatment depends on the type of intestinal obstruction.

What you can do about it

There are a couple of behavioural changes you might consider. Bowels are most active following meals. Start a routine to try to pass the stool at these times. Should you ignore signals to have a bowel movement, these signals will become weaker over time, whereas encouraging the digestive system on a regular basis will have a conditioning effect. Furthermore, you could increase your activity and go for a walk regularly, for example. This will promote bowel movements and relieve constipation.

You should also optimise your liquid intake within the permitted restrictions. While healthy people can drink as much fluid as they want, on dialysis, you can only drink a certain amount of water and other liquids as prescribed. Your gastrointestinal system needs the permitted quantity of fluids to do its job correctly.

If the changes mentioned above do not relieve your constipation, talk to your physician about which type of laxative would be the best choice for you. Laxatives are substances that help relieve constipation in a variety of ways. Milk sugar (lactose) can aid digestion as well. Again, remember to always talk to your physician or dietician first.

How to benefit from dietary fibre

Increasing fibre in your diet may reduce or eliminate constipation. Dietary fibre is found in plant-based carbohydrates such as fruits, vegetables and grains.2 As it is the part of plant food which is not digested in the small intestine, it reaches the large intestine or colon. Fibre-rich foods typically contain two types of fibre, soluble and insoluble. Soluble fibre dissolves in water and creates softer, larger stools. Insoluble fibre does not dissolve in water. It actually takes in water and gives bulk to a bowel movement, making the stool easier to pass.3 Both types generally help waste get through the digestive tract more quickly.

The recommended daily fibre intake for the general population is > 30 g.4 You should gradually increase the fibre in your diet. This gives your bowel time to adjust to each level of increase before you move up to a greater amount. Lots of fibres are contained in the skin of fruits, so it is better to not peel them and to eat the whole fruit.

However, it is hard to get enough fibre in your renal diet for several reasons. Many high-fibre foods are also high in both potassium and phosphorus1,2and you may have to avoid or limit them if you need to follow potassium or phosphorus restrictions in your diet. Also, when you eat more high-fibre foods, you need to increase your fluid intake. It is essential, though, to ensure that you stay within your fluid allowance.

The higher level (35 g a day) of fibre may be impossible to reach for a person with kidney disease.2, 5 It is a good idea to carefully monitor what you eat and drink for a few days. A food diary will help you to have a constructive discussion with your physician or dietician to determine whether your choice of foods is suitable for your current condition.

Some fruits and vegetables that are high in fibre are also high in potassium.1 You may have to avoid them or limit them if you need to follow potassium restrictions in your diet.

Here is a list of selected foods which are rich in fibre and lower in potassium:


raspberries, blackberries, pears, apples, strawberries, blueberries, oranges, cranberries, cherries, peaches, rhubarb.


Raspberries, blackberries, pears, apples, strawberries, blueberries, oranges, cranberries, cherries, peaches, rhubarb.


Broccoli, cauliflower, zucchini, carrots, corn, cabbage, sweet potatoes, aubergines, endive, squash.


Peas (frozen or from the jar), green and yellow beans

Grains and grain products

Whole-grain is higher in fibre content than refined grains, but also contains more phosphate. It is still preferable, as the human body can only partly digest this form of phosphate.4 It can absorb only 40 – 60% of the “unwanted” phosphates in these foods.

You do not have to eliminate certain foods just because you have chronic kidney disease. Always make sure to consume them in proper amounts. It is advisable to eat all your planned fruits and vegetables for the day and drink the amount of liquids permitted. This will support your digestion in the best possible way while adhering to your diet plan.


  1. Can Outcomes be Improved in Dialysis Patients by Optimizing Trace Mineral, Micronutrient, and Antioxidant Status?: The Impact of Probiotics and a High-Fiber Diet. Bossola M. Semin Dial. 2016 Jan-Feb;29(1):50-1. doi: 10.1111/sdi.12442. Epub 2015 Sep 19.
  2. Dietary protein and fiber in end stage renal disease. Sirich TL. Semin Dial. 2015 Jan-Feb;28(1):75-80. doi: 10.1111/sdi.12315. Epub 2014 Oct 16.
  3. Sirich TL, Plummer NS, Gardner CD, Hostetter TH, Meyer TW: Effect of increasing dietary ber on plasma levels of colon-derived solutes in hemodialysis patients. Clin J Am Soc Nephrol 9(9):1603–1610, 2014.
  5. Bossola M, Leo A, Viola A, Carlomagno G, Monteburini T, Cenerelli S, et al.: Dietary intake of macronutrients and ber in Mediterranean patients on chronic hemodialysis. J Nephrol 26:912–918, 2013.

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