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.”
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.
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.