Natural phosphate and added phosphate – what you need to know

When you have chronic kidney disease (CKD), you may need to manage the levels of phosphate in your diet. Understanding the difference between natural phosphate and the phosphate found in processed foods will help you make the healthiest choices for you, with the support of your kidney dietitian.

Phosphate is a chemical containing the mineral phosphorous, which our bodies need to make energy, help our nerves and muscles work properly and keep our bones strong.

It’s found naturally in some foods but we get most of our intake from processed foods, and because UK diets are high in these, our average phosphorous intake is around 1400mg a day – over the recommended adult requirement of 550mg.

“In healthy people, the kidneys deal with it, although it’s probably not good for anyone to have lots of phosphates from processed foods,” says kidney dietitian Teresa Howes. “But when you have CKD, reduced kidney function means you don’t filter out phosphate very well, so levels in your blood can rise.” When that happens, calcium can come out of bones, making them weaker and leaving deposits in your arteries, leading to heart and blood vessel disease, known as chronic kidney disease mineral bone disease (CKD-MBD).

Natural or added phosphate: understanding the difference

Natural phosphate (organic phosphate)

Natural phosphate is found in plant foods like nuts, seeds, legumes and pulses, and protein foods, such as meat, fish and dairy.

We absorb between 20% (plant foods) and 60% (animal foods) of the natural phosphate in our diets.

You may also hear it called ‘organic phosphate’ but that doesn’t mean it’s only in the organic foods grown without chemicals. Used in this way, ‘organic’ just means something that occurs naturally.

Added phosphate (inorganic phosphate)

Added phosphate – sometimes called ‘inorganic phosphate’ – is the type added to lots of processed foods because it has lots of uses.

As our diet is high in processed food, and we absorb 90-100% of the added phosphate we get from it, this type of phosphate makes up our biggest intake.

Managing phosphate levels: how your kidney dietitian can help

“If you have high phosphate levels because of CKD, your kidney dietitian will check your bloods regularly,” says Teresa. “They’ll help you get to a safe blood level with personalised advice for a lower phosphate diet that works for you and your lifestyle and includes foods you enjoy. Your dietitian can also help with shopping and meal tips.”

Phosphate levels and CKD: what to eat

Your dietitian will give you individual advice but as a general rule, eat more fruit, vegetables, legumes, pulses and whole grains. You can have some dairy, meat and fish too – in the UK, fresh meat doesn’t have phosphate added.

Focus on reducing processed foods. “Small changes often make a big difference to your phosphate levels,” says Teresa.

A diet high in fresh, whole foods and low in processed foods is good for everyone’s health so you don’t need to eat any differently from the rest of your family – you’ll all benefit. Here are four steps to take.

1. Become a supermarket sleuth

“Get into the habit of reading ingredients lists as phosphates are found in so many foods,” says Teresa. “Levels in the same product can differ between brands and there’s no way to predict it – you may find one brand of custard creams without added phosphate and one with, for example. Lower phosphate versions aren’t necessarily more expensive. Read labels, and remember to check at deli counters, too.”

Understanding labels

You need to look at the ingredients listed on the label – not the nutritional content table.

Phosphate will be labelled as phosphate or phosphoric acid (look out for phos or phosph) or as E numbers.

E-number Name of additives Products which may contain it

E338

Phosphoric acid

Non-alcoholic flavoured drinks

Sterilised and UHT milk

Candied fruits

Beer

Processed meats

Sweets, cake and chocolate

E339

Sodium phosphates

Dried milk powder

UHT cream

Unripened cheeses

Canned soup

Breaded chicken and fish

E340

Potassium phosphates

Processed cheese

Meat products

Sports drinks

Powdered milk

Desiccated coconut

E341

Calcium phosphate

Edible ices

Desserts

Dry powder for dessert mixes

Self raising flour

Instant pasta sauces

E343

Magnesium phosphate

Bakery products

Flour

Liquid egg

Salt substitutes

Prepared mustard

E450

Diphosphates

Bakery products

Meat products

Processed cheese

Sauces

Soups and broths

Instant herbal infusions

Dried powdered food

Milk based drinks

2. Switch to a plant-based diet

This doesn’t mean you have to be vegan or vegetarian – just include more whole grains like rice and porridge, and fruit and vegetables, including fresh, frozen and tinned.

Add flavour with herbs and spices, and try foods like hummus and salad in sandwiches.

“Be aware that plant-based meat alternatives such as burgers may contain added phosphate, so treat these like any other processed food,” says Teresa.

3. Rethink ready meals

Cook meals like stews, curries and pasta sauces in bulk and freeze batches.

“If you’re having dialysis, you could try cooking on days you have more energy, so you have easy meals for the days you’re tired,” says Teresa. “And if you’re cooking a chicken, keep some to have cold in sandwiches. If you rely on meals delivered by a company, ask them for lists of ingredients. Your dietitian can also help you get that information.”

Child baking making cake batter

4. Experiment with recipes

Instead of expensive low-phosphate processed meat, for example, you can make your own versions with budget-friendly ingredients such as mince and chickpeas – the Kidney Kitchen offers hundreds of free recipes to inspire you.

Look through Kidney Kitchen recipes

Love baking? You can find ways to whip up low-phosphate versions of your favourite biscuits and cakes. You’ll find lots of tips on the Kidney Kitchen website.

Kidney-friendly diet information

  • Lowering your potassium levels

    Potassium is a mineral that can build up in your body if your kidneys are not working properly. Some medicines can also increase your potassium levels. Read on for advice to help lower your potassium levels.

  • Choosing a plant-based diet with CKD

    Kidney Kitchen renal dietitian Angeline Taylor explains how eating more plant foods can help you stay well when you are living with chronic kidney disease (CKD).

  • 12 healthy and kidney-friendly lunches

    A balanced diet will help you maintain a healthy weight when you are living with chronic kidney disease (CKD). If you're preparing a light meal, there are lots of tasty and kidney-friendly options to try.