Diet

Diet in Renal Failure

This page deals with What’s In Food. To learn about diet at different stages of renal disease, click on these links:

For The Kidney

Diet for the Failing kidney

Kidney function is essential in dealing with the waste material from ingested food – products including urea from dietary protein is excreted by the the kidneys along with other substances such as sodium, potassium and phosphate. It follows, therefore, that impaired renal function can lead to a build-up of these substances in the body. Dietary restriction can modify this accumulation and its effects.

Should I cut down on protein?

Many renal units advise either protein restriction, or at least avoiding high protein intake for patients with renal failure. Here are the reasons for this:

lowering protein intake may slow down the rate at which the kidneys get worse
it reduces the phosphate load (important to prevent bone and other problems in the future)
it helps to control the acid level in the blood – if the blood is too acid it can lead to loss of muscle and to a high potassium levelĀ in the blood
in advanced (stages 4 and 5) kidney disease it can relieve symptoms such as nausea and vomiting

In most patients it is not recommend to have a protein restriction. This is a change from the past. This is because

very low protein diets are not nice
under-nutrition is a serious problem in many patients with advanced kidney disease
the slowing effects of protein restriction on kidney deterioration are much less in patients with good blood pressure control

What do you do about protein intake?

We assess protein intake at stage 3 kidney disease (30-60% kidney function). If the protein intake is high, we aim to reduce it to 1g/kg (weight is ‘ideal body weight’ – lower than your actual weight if you are overweight, and vice versa).
You could think about it at stage 2 kidney disease or earlier, if you think your intake may be high.
We no longer recommend more severe protein restriction than this for most patients.
Some units do recommend lower protein intakes for certain patients. 0.6-0.8g/kg (ideal body wt) per day (around 40-50g for adults ) can provide the basic protein requirements but only just. Less than this certainly carries a high risk of malnutrition.

Sodium

Common salt is sodium chloride. Very low sodium diets, with food being cooked salt-free, are never recommended in renal failure. The existence of fluid overload (eg swollen ankles) and/or high blood pressure should be managed by a degree of sodium restriction, but not less than that which provides around 100mmol. This allows for salt to be used in cooking, but means avoiding very salty foods such as those listed earlier, and avoiding the addition of salt to food after it has been cooked.

Many of the blood pressure tablets only work properly if combined with a reduced salt intake. Salt restriction is also often necessary to allow for the prescription of sodium bicarbonate to correct the acid level in the blood.

In a very few people it is necessary to encourage a high salt intake – “salt wasters” are patients who pass large amounts of sodium in the urine. This happens in some kinds of kidney disease, and can cause serious salt and water depletion.

Potassium

Potassium is not restricted routinely in patients on conservative treatment of renal failure, but this is sometimes necessary when kidney function has become very poor. Hyperkalaemia, too much potassium in the blood, occurs more usually for reasons other than dietary excess, eg acidosis (too much acid in the blood), or because of the use of certain medicines, such as ACE inhibitors (drugs with a name ending …pril ). Some unlucky people do need to restrict potassium at milder levels of kidney failure.

Fluid

Until end-stage is reached most patients benefit from maintaing a normal fluid intake (e.g. 1.5-2 litres daily). It is important to avoid dehydration as this adversely affects kidney function. Some patients, however, require fluid restriction before starting dialysis. NOTE: it is impossible to stop yourself from drinking if there is too much salt (sodium) in your diet.

Phosphate

Hyperphosphataemia, too much phosphate in the blood, is usually only a problem in the later stages of renal failure although phosphate retention occurs long before it shows up in raised blood levels.
Avoiding excess protein limits the amount of phosphate in the diet too, and there are some foods that can be limited if the level of phosphate in blood rises. However in advanced kidney failure most people require phosphate binding medication before meals. This works by binding phosphate in the gut and preventing it from being absorbed into the body. It is therefore important that it is taken with or just before food . These are medicines such as calcium acetate, Renagel.

Energy

It is essential that patients on protein restriction take a high energy diet. Too few calories leads to the breakdown of muscle to provide energy. This results in an increase in the blood urea and a weak and debilitated patient.
A high Calorie diet should be achieved through increased consumption of foods such as sugar, jam, marmalade etc. but in some cases it is necessary to provide specialised products.

Diabetes and Chronic renal failure

Patients with Diabetic Nephropathy are treated in the same way as non-diabetics. If extra carbohydrate is required this is best from foods rich in complex carbohydrates such as bread, rice and pasta.

On Haemodialysis

Diet on Haemodialysis

The average amount of time spent on haemodialysis is 10-12 hours per week. This means that for over 90% of the week the patient has little or no renal function. It is therefore important to make some adjustments to the intake of food and fluids in order to avoid excessive accumulation of waste metabolites and fluid in the period between dialysis.

Protein

Protein restriction is no longer required once patients are established on regular haemodialysis and patients should eat a normal protein intake of 1g/kg ideal body weight (about 70g each day )

Sodium

Restriction in the form of “No Added Salt” is necessary since a greater intake will result in poorly controlled blood pressure. In addition too much salt leads to excessive thirst, difficulty in adhering to the fluid restriction and subsequent fluid overload / hypertension.

Potassium

It is not possible for the blood level of potassium to be maintained within the normal range and indeed if this was so it could lead to marked hypo kalaemia (low level of potassium) during dialysis.
It is generally felt that a pre-dialysis potassium of up to 6mmol/L is safe.
Patients must be aware of all foods which are rich in potassium but no food needs to be avoided completely due to its high potassium content. See list of high potassium foods.

Fluid

The fluid allowance for each patient is calculated on the basis of ‘urine plus 500ml’. 500ml approximately covers the loss of fluid through the skin and the lungs.
Most patients on commencement of haemodialysis will begin to pass much less urine and a typical fluid allowance is 750ml-1000ml/day. Those who produce a lot of urine can drink more.
Between each dialysis treatment patients are expected to gain a little weight due to the moisture content of foods eg fruit & vegetables.
The amount of fluid in a typical day’s meals (excluding fluids such as tea, water etc) is at least 500ml and therefore we should expect a daily weight gain of 0.4-0.5kg. It follows that each patient is expected to increase their weight between two dialysis treatments by 1-1.5kg. Small adults benefit from smaller weight gains between treatments.

Phosphate

Phosphate is controlled to a certain extent by diet as the protein intake is kept at a normal level – excessive ingestion of protein would lead to poor control of both urea and phosphate.
Phosphate binders are used in the same way as described in diet for the failing kidney with the aim of acheiving a pre-dialysis level of 1.5-2mmol/L.
If the level falls below 1.5mmol/L the amount of phosphate binder should be reduced.

On Peritonal Dialysis

Diet on Peritoneal Dialysis

When this form of renal replacement therapy was first used in the 1970s it was thought that one of the great advantages of the treatment would be the disappearance of dietary and fluid restrictions. Unfortunately this did not prove possible !

Protein

Each time the dialysate is drained out there is a small loss of protein and over the course of the day this adds up to 5-10g.
It is therefore important to compensate for this by recommending a higher protein intake – it has been suggested that patients should consume as much as 1.5g/kg daily but this is very difficult to acheive especially in the elderly.
An intake of 1.1-1.2g/kg ideal body weight is more realistic.

Sodium

Ideally “No Added Salt” is recommended but in order to achieve a higher protein intake it may be helpful to relax the sodium restriction a little if other factors permit it.
Too much salt or sodium will lead to difficulty in complying with the fluid restriction.

Phosphate

Phosphate control is much better than in haemodialysis and it is common for people not to require phosphate binders or at least to have spells off this medication.

Fluid

The optimum fluid allowance for each patient is much more difficult to calculate since it is not simply related to the urine output in the same way as in haemodialysis.
The clearance of fluid across the peritoneum (ultrafiltration) varies from person to person, and indeed some people are not suitable for CAPD due to poor fluid removal.
Once the fluid allowance is established, during the training period, it is important to maintain this and to try to avoid the use of hypertonic dialysate (‘heavy bags’). A typical fluid allowance on CAPD is 1 litre per day.

Energy

As with any other treatment it is important to maintain nutritional status and to try to achieve a normal weight for height. This can prove difficult in CAPD as some patients eat poorly, especially the elderly, whilst others gain excessive body weight.
The glucose in the dialysis fluid contributes significantly to energy intake. Calories from the glucose absorption can amount to as much as 500 per day.

Potassium

One of the main differences between the diets for haemodialysis and CAPD is the recommended intake of potassium. The continuous uptake of glucose from the dialysis fluid is one factor which influences the potassium balance.

Patients on CAPD are more likely to be hypo kalaemic (have a low level of potassium in the blood) and require a high potassium intake – in some instances potassium tablets are required but it is preferable to increase dietary potassium intake.
There are, however, some patients who require potassium restriction in the same way as those on haemodialysis.

Fibre

Patients are encouraged to increase their intake of fibre to avoid constipation as this can lead to problems with the catheter position resulting in poor drainage of the dialysate.

After Transplant

Diet after a Renal Transplant

You should not need a special diet if your new kidney is functioning well, but this is a good time to think about your general health and the positive things you can do to improve it.

Many common health problems such as heart disease can be linked to a poor diet and lifestyle – healthy eating is an important part of keeping fit ,and is one of the positive things you can do to improve your health. Healthy eating is not a ‘diet ‘ – it requires a gradual change in your eating behaviour and should become a regular part of your lifestyle.

Healthy eating involves:

Enjoying what you eat and having a varied diet
Eating more fruit and vegetables
Cutting down on fat, sugar and salt
Being a healthy weight
Limiting alcohol to below recommended weekly limits (21 units for men,14 for women)

You should get more information about healthy eating and food safety before you are discharged home.

Will I gain weight after my transplant?

Many people gain weight following a transplant,especially in the first year. This can be due to freedom from dietary restrictions, feeling well, increased appetite and lack of exercise. This is not helped by steroids which are necessary after a transplant.

Maintaining a healthy weight is very important for your health as being overweight puts a strain on your body contributing to many health problems including high blood pressure, heart disease and diabetes.
If you are overweight it is worthwhile trying to lose some weight before you receive your transplant -if you wish to discuss this please ask to speak to your dietitian.

It is possible to maintain a healthy weight after your transplant if you make the necessary changes to your diet at an early stage. Remember – it is much easier to prevent weight gain than it is to try to lose weight, and it is sensible to make changes to your eating habits as early as possible to prevent weight gain.

Advice on how to achieve and maintain a healthy weight will be tailored to your individual needs and should be discussed with the dietitian before you are discharged.

What’s in food?

Kidney function is essential in dealing with the waste material from ingested food – urea is made from dietary protein and is excreted by the kidneys along with other substances such as sodium, potassium and phosphate.
Impaired renal function can lead to a build-up of these substances in the body.
Dietary restriction can modify this accumulation and its effects.

Protein Sodium Potassium
Fluid intake Phosphate Energy
Fibre Diet after Transplant

Protein

Excessive intake of protein must be avoided, and sometimes protein restriction is advised for patients with renal failure. Here are the reasons:

lowering protein intake may slow down the rate at which the kidneys get worse
it reduces the phosphate load (important to prevent bone and other problems in the future)
it helps to control the acid level in the blood – if the blood is too acid it can lead to loss of muscle and to a high potassium levelĀ in the blood
in advanced (stages 4 and 5) kidney disease it can relieve symptoms such as nausea and vomiting

It is recomended to most patients that a protein restriction is not imposed as it can interfere with eating a healthy diet.

On haemodialysis protein restriction is not generally required once patients are established and patients should eat a normal protein intake of 1 g/kg ideal body weight, about 70g each day.

In CAPD a higher protein intake is recommended due to a small loss of protein from the drained fluid (dialysate) which adds up to 5-10g over the day. It has been suggested that as much as 1.5g/kg of protein daily should be consumed but this is very difficult to achieve. An intake of 1.1-1.2g/kg ideal body weight is more realistic.

Protein

A typical daily intake in the UK is 60 – 80g.
Normal requirement is only 45-55g
The richest sources are: Animal protein – meat, fish, cheese, eggs and milk
Vegetable protein – nuts,beans, pulses,soya milk

Sodium

Common salt is sodium chloride. Very low sodium diets, with food being cooked salt-free, are never recommended in renal failure. The existence of excess fluid in the body (eg swollen ankles) and high blood pressure should be managed by some sodium restriction to 100mmol per day. This allows for salt to be used in cooking, but means avoidance of very salty foods, and avoiding the addition of salt to food after it has been cooked. Many blood pressure tablets only work properly if combined with a reduced salt intake.

On haemodialysis, restriction in the form of “No Added Salt” diet is necessary since a greater intake will result in poorly controlled blood pressure.

On CAPD, there is a “no added salt” restriction for the same reasons.

On dialysis too much salt leads to excessive thirst, difficulty in adhering to the fluid restriction and risk of excess fluid and high blood pressure. A number of salt substitutes are available but they consist mainly of potassium chloride and therefore salt substitutes are not usually suitable for patients with renal failure.

Sodium

A typical daily intake in the UK is 150 – 200mmol (9-12g of salt, or 3-5g of sodium)
Only around 10% of this is found in fresh food, the remainder is added as sodium chloride or sodium bicarbonate in cooking and food processing, and as table salt which may be sprinkled on the food after cooking.
Sodium rich foods:
cheese, bacon, ham, sausages, tinned meat eg.corned beef, meat + fish paste
Oxo, Bovril, Marmite, salted butter & margarine, tinned vegetables, tinned & packet soups salted nuts & crisps, salty biscuits eg TUC, Cheddars
Other sources of sodium:
Effervescent pain-killers – may contain up to 20mmol sodium per tablet!
Antacids and some other medicines

 

Potassium

Potassium is not restricted routinely in patients on conservative treatment of renal failure.
Too much potassium in the blood (hyperkalaemia), often occurs for reasons other than dietary excess like too much acid in the blood. Sometimes dietary potassium may have to be restricted for instance in diabetics and those on ACE inhibitors, drugs with a name ending …pril for control of high blood pressure.

On haemodialysis , potassium is reduced during each dialysis treatment then usually rises between treatments. It is felt that a pre-dialysis potassium of up to 6mmol/L is safe. Patients must be aware of all foods which are rich in potassium but no food needs to be avoided completely due to its high potassium content.

On CAPD , it is more common to have a low level of potassium in the blood (hypokalaemic) and require a high potassium intake. One of the main differences between the diets for haemodialysis and CAPD is the recommended intake of potassium. The continuous uptake of glucose from the dialysis fluid may influence potassium balance. Some patients still require potassium restriction in the same way as those on haemodialysis.

Potassium

A typical daily intake in the UK can vary from 50 to 150mmol
Potassium is always found in association with protein and therefore all the protein-rich foods, especially milk, contribute significantly to the daily intake of potassium
Other rich sources of potassium are: Potatoes – especially baked, chips & crisps (boiling leaches out a lot of potassium); bananas, grapes, rhubarb, fresh grapefruit, fresh pineapple, Kiwi fruit,dried fruit eg currants, sultanas, dates, pure fruit juice including apple juice (even though fresh apples are low in potassium) tomatoes, butter beans, sweetcorn, mushrooms, beetroot, sprouts, leeks chocolate (plain contains less than milk) liquorice, fruit gums, coffee.
Coca-Cola & diluting fruit squash contain negligible amounts of potassium.

Fluid Intake

All drinks contain mostly water. Fluids refer to all drinks taken per day. Until the kidneys fail and dialysis is required, a fluid intake of 2 litres is encouraged – it is important to avoid dehydration as this can affect the kidney function.

On haemodialysis the fluid allowance for each patient needs to be quite strictly controlled.

The optimum fluid allowance when on CAPD is more difficult to calculate. The amount of fluid removed varies from person to person and sometimes CAPD is not suitable, due to poor fluid removal (ultrafiltration). A typical fluid allowance on CAPD is 1 litre per day.

Phosphate

Too much phosphate in the blood (hyperphosphataemia), is usually only a problem in the later stages of renal failure although phosphate retention occurs long before it shows up in raised blood levels. The renal diet is automatically low in phosphate due to the protein restriction and if the phosphate rises above the upper limit of the normal range it can only be treated by using phosphate binding medication before meals. This medication works by binding phosphate in the gut and it is therefore important that it is taken just before food.

The commonest binders are calcium acetate (Phosex) or calcium carbonate (Calcium 500 or Calcichew), or sevelamer (Renagel). Renagel is a modern alternative but it is expensive and requires a lot of tablets.

On dialysis phosphate is controlled to a certain extent by diet. Phosphate binders are used in the same way as prior to dialysis with the aim of acheiving a pre-dialysis level of 1.5-2mmol/L.

Phosphate

A typical daily intake of phosphorus in the UK is 35-40mmol
Phosphate, like potassium, is found in association with protein, especially in milk and cheese. Only a few other foods which contain phosphate like wholegrain cereals (wholemeal flour and bread, oatcakes). Other sources are convenience foods which have phosphates added by the food manufacturers.

Energy

It is essential that patients on a protein restriction take a high energy diet. Too few calories lead to the breakdown of muscle to provide energy. This results in an increase in the blood urea and a debilitated patient.
A high calorie diet should be achieved through high energy foods such as sugar, jam, marmalade etc. but in some cases it is necessary to provide specialised products which are produced commercially.

Fibre

The intake of fibre is encouraged to avoid constipation. This can be important in CAPD as constipation can cause problems with the catheter position and result in poor drainage of dialysate.

Diet after Transplantation

A successful transplant allows dietary freedom, but in particular freedom to drink. A healthy diet is encouraged with avoidance of excessive use of salt or sugar along with high fibre and low fat – the latter is important due to the high cholesterol and other lipids frequently found in blood testing of transplant patients. It is also important to maintain a healthy weight.