"...all doctors should be able to diagnose and treat nutritional deficiencies."

Royal College of Physicians. Nutrition and Patients: A Doctor's Responsibility. London 2002


This page has been printed from the www.stewartnutrition.co.uk web site.

Renal Impairment

Kidney disease is another common disease which affects a high percentage of the population many of whom will need to take care with their diet as well as choice of nutritional supplements.  According to Kidney Research UK www.kidneyresearchuk.org nearly 3 million people in the UK are at risk of developing or have developed kidney disease (Stages 3,4 or 5).  Estimates suggest that approximately 250,000 have a degree of impairment that means they either have symptoms or should be taking care with their diet.   This also means that they should also be mindful of the type of nutritional supplements that they are taking.

There are particular concerns about the minerals potassium and magnesium as well as vitamin A – retinol as the body controls the balance of these nutrients by excreting any excess in the urine.  This ability is lost with progressive renal disease and toxicity can result from either poor food choices or taking potentially dangerous supplements.

Patients with kidney disease especially stages 4 and 5 should ignore any normal safety guidelines on supplements as these apply to those in good health and should take no supplements without the express permission of their renal specialist.
Those with stage 3 disease may also need to take care not to exceed Safe Upper Levels or Guidance Levels for the above three nutrients especially if their renal function is deteriorating
Supplements of vitamin B, C, zinc at low doses are usually considered to be safe but should only be taken with medical approval.


This mineral can accumulate in those with chronic renal disease and cause cardiac problems.  Patients with more advanced liver disease are often placed on a low potassium diet.  Very few nutritional supplements will contain significant amounts of potassium.


This mineral can accumulate in those with chronic renal disease and cause low blood pressure, fatigue and cardiac problems.
This mineral may be found in some calcium preparations as well as multiminerals and  A to Z multivitamin/mineral preparations.  Magnesium salts are often used as an excipient (filler) in many medicines.

Vitamin A - Retinol

This vitamin can accumulate in those with chronic renal disease and may contribute to the risk of osteoporosis developing.
Symptoms of excess include headache, hair loss and muscle pains.  High blood calcium levels can develop and if this is a feature of the patient’s health problems then the serum retinol levels should be measured. 
Retinol excess can also develop in those on dialysis.
Because retinol is stored in the liver and any excess can take up to 2 years to deplete it is prudent for those with stage 3 disease that is progressive not to take supplements of retinol, which will include cod liver oil and the majority of multivitamin preparations, unless advised to do so by their doctor.

Copyright Dr. Alan Stewart M.B.B.S.M.R.C.P. (UK)M.F. Hom.
47 Priory Street, Lewes, East Sussex. BN7 1HJ
Tel 01273 487003 Fax: 01273 487576