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FAQ Category: Frequently Asked Questions

Phosphate Additives and the Kidney Diet

‘Advice from the Kidney (Renal) Dietitians on the importance of avoiding food containing phosphate additives’

Phosphate additives are added to foods for many reasons. They can be used to extend shelf life, improve colour, enhance flavour, or retain moisture.
The phosphates in food additives are especially dangerous if you have kidney disease since our bodies absorb them much more efficiently than the phosphates that occur naturally in foods like dairy foods, lentils and whole-grains.
Unfortunately there is no complete list of all foods containing phosphate additives because there are too many of them. Some examples of processed foods which may contain these additives are listed below.

Processed meats, processed fish and cheese, dried foods, dessert and cake mixes, cola drinks, alcoholic beverages, salt substitutes, instant pasta, sauces and bakery products.

Many products marketed as “low sodium” contain high amounts of phosphate additives. Cold meats with phosphate additives may contain up to 70% more phosphates than brands containing no additives.

How to avoid phosphate additives in your Kidney Diet = Read the Labels
Reading labels is the key. Try to read the food labels of processed foods that you use regularly. Food additives are considered ingredients and must be listed in the ingredients list by specific name or designated E number.

The most common ones are listed below:

E338    Phosphoric acid

E339    Sodium phosphates

E340    Potassium phosphates

E341    Calcium phosphates

E343    Magnesium phosphates

E450    Diphosphates

E540    Dicalcium diphosphate

E541    Sodium aluminium phosphate

E542    Bone phosphate

E544    Calcium polyphosphates

E545    Ammonium polyphosphates

Foods containing these ingredients are best avoided on the Kidney (Renal) Diet.

Compare products and choose those without phosphate additives.

Look for foods labelled “free from artificial colours, flavours and preservatives”.

If you need help or advice ask your Kidney (Renal) Dietitian.

Can you give me some alternatives to salt?

There are a variety of herbs and spices that can be used as a substitute for salt from garlic and pepper to basil, oregano and rosemary. You can flavour your meals in many different ways. Remember to use herbs and spices sparingly.

Some suggested flavour combinations:

Food                              Suggested flavouring

Beef:                                  Allspice, dry mustard rubbed into the meat before cooking, oregano, bay leaf, chilli powder, cayenne pepper
Fish:                                   Vinegar, lemon, dill, mint, thyme, garlic, chilli
Pork:                                  Cloves, apple, garlic, onion, sage, curry powder
Chicken:                            Lemon, garlic, tarragon, rosemary, sage, thyme, chilli powder, cayenne pepper, paprika
Stews & casseroles:        Bouquet garni, oregano, sage, thyme, basil, garlic


Low salt gravy


  • Meat juices
  • Gravy browning (to add colour and flavour)
  • Cornflour
  • Flavourings such as herbs, spices, onions


  1. Allow the meat juices to cool and skim off the fat.
  2. Thicken with cornflour.
  3. Add gravy browning until the desired colour is reached.
  4. Don’t use stock cubes or gravy mixes.



  • 3 tablespoons/ 50ml oil (olive oil or rapeseed oil)
  • 2 tablespoons/ 30ml wine vinegar
  • 1 clove of garlic – chopped
  • Black pepper
  • Parsley and thyme/ alternative herbs or spices as desired


  1. Place all ingredients in a non metallic bowl
  2. Place the meat/ fish/ poultry pieces in the bowl and cover with the marinade and stir well.
  3. Cover the bowl and place in the fridge
  4. Marinade for 15 min to 2 hours depending on how strong you want the marinade flavour to be.

Is diet really that important?

No matter what stage of Chronic Kidney Disease…

diet plays an essential role in treating kidney disease. In early Chronic Kidney Disease, restricting protein intake to a moderate level may help delay the progression of disease. This restriction should be planned carefully with your Kidney (Renal) Dietitian to avoid nutrient deficiencies occurring.

High blood pressure…

is one of the leading causes of Chronic Kidney Disease, and salt has been shown to play a role in contributing to high blood pressure. A lot of the salt we take is hidden in processed or packaged foods. You could start by cutting back on processed foods (such as packet soups and sauces, processed meat and meat products) and choosing more fresh foods. Using herbs and spices instead of salt in cooking and at the table will help flavour your food. See the section on food labels for more information on what to look out for when reading food labels.

Diet helps control high potassium and phosphate levels…

which can develop in kidney disease. At all stages of Chronic Kidney Disease, restricting salt intake is very important for controlling blood pressure and helping to reduce fluid overload.

For individualised dietary advice, talk to your Kidney (Renal) Dietitian or ask your Doctor to refer you to one.

How should I begin changing my diet when I have early Chronic Kidney Disease (CKD)?

Chronic kidney disease (CKD) usually develops gradually over time…

so if you find out you have kidney disease; you have an opportunity to slow down the loss of kidney function by making some changes to your diet and lifestyle.

If you have high blood pressure…

controlling your blood pressure is a very important way to help slow down the decline in kidney function. Dietary measures to help control blood pressure include reducing salt intake, drinking less alcohol and losing weight if overweight. Lifestyle measures such as stopping smoking and taking regular exercise will also help control blood pressure.

If you have diabetes…

controlling your blood sugar (glucose) levels and maintaining a healthy weight, or losing weight if overweight will help slow the development of kidney disease.

If you have raised cholesterol levels…

dietary measures including reducing your total fat intake; and your intake of saturated fat (including butter, fat on meat/ skin on poultry), can help lower cholesterol and thereby reduce your risk of heart problems.

In early CKD…

keeping your portions of protein rich foods (such as meat, fish, eggs, dairy products and pulses) to modest amounts may help to slow down the decline of kidney function. It is important to include protein foods in your diet, however large portions are not recommended. Your Kidney (Renal) Dietitian can give you more individual advice.

What should I use to treat a low blood glucose (sugar) or hypoglycaemia?

You should treat a low blood glucose (sugar) level immediately

with rapid-acting carbohydrates such as:

  • 150mls ordinary 7up or orange (small glass)
  • 5 dextrose/ Lucozade tablets

It is therefore important to carry a hypo treatment

with you at all times. After 10-15 minutes check your blood glucose (sugar) levels again:

If less than 4mmol/L

take another rapid acting carbohydrate source as above.

If greater than 4 mmol/L

and you are due a meal or snack within the next hour, you will not need to take any additional carbohydrate until then.  However, if not eating for over an hour you should take additional carbohydrate to maintain your blood glucose (sugar) such as:

  • A slice of bread
  • A digestive / 2 Rich tea biscuits
  • A portion of fruit

Foods which are NOT suitable  for immediate treatment of low blood glucose (sugar) include: chocolate, crisps, biscuits, sandwich, cup of tea with milk and sugar. This is because it takes too long for the glucose (sugar) to be released from these foods. Orange juice is not suitable as it is high in potassium.

Important Notice:

The nutritional content of Lucozade Energy is changing

The carbohydrate content of Lucozade Energy is being reduced by approximately 50%. Therefore you will need to take more Lucozade to correct your hypoglycaemic (low blood sugar) episode.

From April 2017, the new Lucozade bottles and cans will be available.  For a period of time, both old and new versions may be on the shelves together.  It is therefore important that you remember to check the label for the amount of carbohydrate it contains.

To correct a hypo (low blood sugar level) you need to take 15g of rapidly absorbed carbohydrate.  The new Lucozade product contains 8.9g carbohydrate per 100mls.  Therefore you will now need to take 170mls to get 15g of carbohydrate to correct your hypo.

It is important to check labels regularly to ensure you are getting the right amount of carbohydrate as other brands of fizzy drinks may also change their sugar content

Barbara Gillman, Clinical Specialist Renal Dietitian, Mater Misercordiae University Hospital

Why is white bread suggested for the renal diet?

White bread is lower in potassium and phosphate than whole meal bread…

and therefore is recommended for those with reduced kidney function, particularly if your blood levels of potassium and phosphate are high.

As kidney function declines…

so does the kidney’s ability to filter potassium and phosphate.

To limit potassium and phosphate…

choose lower potassium and phosphate products like white bread (sliced or rolls), granary bread, ciabatta or white pitta bread.

What vitamins do I need if I have kidney disease?

Those on dialysis…

are at increased risk of reduced vitamin levels due to losses during dialysis and dietary restrictions. A daily water soluble vitamin supplement which is suitable for renal patients may be recommended by your Kidney (Renal) Dietitian. It is advisable to discuss any vitamin / mineral supplements you are taking with your doctor / Kidney (Renal) Dietitian.

How do you read a food label for salt / sodium?


Product labels on many foods show how much sodium (mg/g) or salt (mg/g) they contain. Sodium is not the same as salt. Salt is sodium chloride so sodium is just one part of a molecule of salt. Many labels provide sodium content but not the salt content which can be confusing. If the salt content is not available on a label you can calculate it from the sodium content using the following:

Sodium x 2.5 = salt content or Salt ÷ 2.5 = sodium content


If you have kidney disease a good goal for sodium intake is 2300 mg of sodium or 6g salt per day. Check with your Doctor or Kidney (Renal) Dietitian to confirm what your maximum daily salt (sodium) limit should be.

Nutrition information may be presented in two ways.

Per serving – shows the amount of each nutrient that is contained in a specified serving size. If using this information, check if your portion is larger or smaller, for example a bowl of cereal may be presented as 30g on the nutritional information but your bowl may contain 50g. You would therefore calculate your portion’s nutritional content as follows:

Calories : (110 /30 ) x 50 = 183 calories


Per 100g – shows the amount of each nutrient that is contained in 100g of the food. If a portion contains more than 500mg/0.5g of sodium or 1.25g of salt it is a high salt option.

What do Dietitians do?

A Dietitian is a food and nutrition expert….

During the stages of kidney disease you may need to alter the foods you eat.

This is because patients with kidney disease must take care when it comes to the foods they choose…

as some may be harmful to their health.

The Kidney (Renal) Dietitian can advise and explain the best food choices for your stage of kidney disease…

and help you maintain good nutritional health. Each individual with kidney disease will have specific dietary needs and your Kidney (Renal) Dietitian will guide you on the best food choices for you

I use sea salt. Is this healthier for me than table salt?

When following a renal diet you will be asked to limit your salt intake…

Salt is mostly made up of the minerals sodium and chloride. You may see sodium or sodium chloride written on food labels instead of salt.

Limiting your sodium intake…

helps keep blood pressure under control and minimizes swelling in the body (oedema).

Sea salt is made from evaporated sea water…

 with little processing and contains trace amounts of minerals that may give it a different flavour or colour than table salt whereas table salt is mined.

However, sea salt and table salt contain about the same amount of sodium…

Try to avoid adding any salt to your food.
Even without adding salt to your food, you can easily get more than you need by eating foods that have a high salt content. Try to choose fresh foods instead of processed and canned food.

What vitamins do I need to avoid if I have kidney disease?

Kidney disease patients should avoid taking any multivitamin…

without first speaking with your Doctor or Kidney (Renal) Dietitian.

Some people with kidney disease need to take renal specific vitamin supplements…

including a form of Vitamin D, water soluble vitamins and folic acid.

This should only be done…

under the supervision of your Doctor or Kidney (Renal) Dietitian.

Does soaking potatoes remove potassium / Does it remove as much as double boiling?

Soaking potatoes may remove some potassium but it will not remove as much as double boiling.

There are two cooking methods you can use to significantly reduce the potassium content in your potatoes. The first method is often referred to as “double boiling”. The second method involves cutting the potatoes into smaller pieces and cooking in a much larger volume of water.

Method 1:

Peel the potatoes and cut into thin slices. Bring to the boil, using four times as much water as potatoes. Throw the water away, and replace with the same volume of fresh boiling water. When cooked, drain and measure your allowance.

Method 2:

Peel and dice potatoes into 1cm cubes. Bring to the boil in 10 times as much water as potatoes. Cook until potatoes are soft. When cooked, drain and measure your allowance.

These methods will reduce the potassium content by at least half the original amount.

If boiling isn’t the planned cooking method, potassium may still be reduced by slicing or cutting potatoes into small pieces or grating them and soaking them in a large amount of water at room temperature or warmer for greater potassium removal.

The least effective method of removing potassium is to soak potatoes in the fridge, then prepare without boiling first.

It is still very important to watch your portion size of potatoes, as even “double boiled” potatoes still contain a considerable amount of potassium.

What are high potassium foods?


is a mineral that is in many of the foods we commonly eat. It is true to say that some foods contain higher amounts of potassium than others.

You may need…

to restrict the amount of potassium in your diet if you have a high potassium blood level and depending on the stage of your kidney disease.

In general all fruit, vegetables and potatoes…

are high in potassium and within this, some have higher amounts when compared to others.

As a general rule…

the high potassium fruits are bananas, all dried fruits and fruit juices. Some other foods known to be high in potassium include coffee, chocolate, salt substitutes, beer wine, nuts and crisps.

The portions of these foods you eat are important…

you will need to talk to your Kidney (Renal) Dietitian about this as every individual is different.

The cooking method used for high potassium foods…

like vegetables and potatoes can also be important. Boiling all vegetables and potatoes and possibly ‘double boiling’ potatoes may be needed depending on your stage of kidney disease. Here’s a low potassium potato cooking method.

Is eating protein unhealthy for people with chronic kidney disease?

No. Protein is an essential nutrient for everybody as part of a well-balanced diet.

However… the amount you need each day will depend on the stage of your kidney disease.

As your kidney disease progresses… you may be told to reduce your protein intake. This is because your kidneys may not be able to able to excrete the waste products if you eat too much.

With end stage kidney disease… if you are on dialysis you will need to eat more protein each day as protein is lost from your body during the dialysis procedure.

The exact amount of protein required… is individual for everybody and is based on your body weight. Talk to your Kidney (Renal) Dietitian about how much protein you need and which food sources are best for you.

What are some of the foods that have the highest phosphate?


is a mineral found in most foods we commonly eat. The foods considered to have the highest amounts of Phosphate are protein rich foods such as dairy based products (e.g. milk/cheese/yoghurts) and all types of meat, fish and poultry.

It is important…

to note that protein rich foods should not be excluded from your diet as protein has many important functions. To clarify whether you need to restrict your phosphate intakes and how to do it without compromising your protein intake you should contact your Kidney (Renal) Dietitian for guidance.

Other high phosphate foods…

include nuts, seeds, wholegrain foods and foods containing bran. Phosphate food additives also contribute significantly to the amounts of Phosphate in our diets.

To help avoid these additives…

it would be important to read food labels and identify the foods where Phosphate has been added. ‘Phosphate’ can be labelled in a number of ways such as; phosphorous, phosphates, hexametaphosphates, diphosphates, triphosphates, polyphosphates etc.

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