Diphosphates
Phosphate salts used to retain moisture, bind meat proteins, and leaven baked goods. Widely used in processed meat, processed cheese and baking powder.
Phosphate from food additives is absorbed almost completely, unlike phosphate from natural foods. High additive-phosphate intake is linked to poorer kidney function, higher serum phosphate, and cardiovascular strain, particularly in people with existing kidney disease.
What is it?
Diphosphates (also called pyrophosphates) are salts of diphosphoric acid. The E450 group covers several mineral salts: disodium diphosphate (E450i), trisodium diphosphate (E450ii), tetrasodium diphosphate (E450iii), dipotassium diphosphate (E450v), tetrapotassium diphosphate (E450vi), and dicalcium diphosphate (E450vii). They belong to the broader phosphate additive family E338 to E452.
What does it do?
Diphosphates work in several ways depending on application. In processed meat and fish, they bind muscle proteins, increasing water-holding capacity so the product stays moist after cooking and retains weight. In processed cheese, they act as emulsifying salts, dispersing milk proteins into a smooth, meltable structure. In baking powder and self-raising flour, disodium diphosphate reacts with sodium bicarbonate when heated to release carbon dioxide, causing the product to rise. They also chelate metal ions, which slows rancidity in fats.
Where you will see it
Processed and reformed meats (ham, bacon, chicken nuggets, burgers, sausages), canned fish, processed cheese slices and spreads, baking powder, self-raising flour, cake mixes, frozen potato products, instant noodle seasoning, and some breakfast cereals. On a UK ingredient list, look for: diphosphates, disodium diphosphate, tetrasodium pyrophosphate, sodium pyrophosphate, or E450.
What the science says
Bioavailability: additive phosphate vs natural phosphate
Phosphate bound to protein in natural foods is only 40 to 60 percent absorbed, because digestion must first free it from the protein matrix. Inorganic phosphate salts used as additives are absorbed at around 90 percent or more, because they are already in their free ionic form. This means a gram of phosphate from a processed food additive raises serum phosphate far more than a gram from chicken breast or lentils. Researchers have flagged this as a clinically important distinction that food labelling currently does not communicate.
Phosphate bioavailability from inorganic additive sources is approximately 90 percent, compared with 40 to 60 percent from organic (protein-bound) sources in natural foods.
Food additives are a major source of highly bioavailable dietary phosphorus, and their contribution to total phosphorus intake is not captured by current food composition databases.
Kidney disease: particular risk for people with reduced kidney function
Healthy kidneys excrete surplus phosphate efficiently. When kidney function is reduced, phosphate accumulates in the blood, stimulating parathyroid hormone and FGF23, both of which are associated with accelerated kidney decline, bone disease, and vascular calcification. For people with chronic kidney disease, dietary guidance consistently recommends avoiding phosphate additives specifically. The concern is most acute in people who already have kidney disease, but some research suggests that high additive-phosphate intake may also stress the phosphate-excretion system in people with normal kidney function.
Epidemiological data link higher serum phosphate to increased cardiovascular mortality and faster CKD progression, even at serum phosphate levels within the normal reference range.
Dietary phosphate additive avoidance is a recommended strategy in chronic kidney disease management; phosphate additives are considered uniquely harmful due to near-complete intestinal absorption.
Food additives containing phosphorus in ultra-processed foods are associated with adverse outcomes for people with chronic kidney disease, and current food labelling does not distinguish additive from natural phosphate.
Cardiovascular risk in the general population
Observational studies in people without known kidney disease have found associations between higher dietary phosphate intake and markers of cardiovascular risk, including arterial stiffness and left ventricular hypertrophy. The mechanism proposed is phosphate-driven FGF23 elevation, which has direct effects on the heart and vessels. However, these studies cannot rule out confounding from overall ultra-processed food intake, and no randomised trial has tested phosphate restriction in people without kidney disease. The evidence is suggestive, not conclusive.
Industrial use of phosphate food additives has been proposed as a mechanism linking ultra-processed food intake to cardiorenal disease risk, with FGF23 elevation as the mediating pathway.
Associations between serum phosphate and cardiovascular outcomes were found in epidemiological studies, but consistent causal evidence in the general population remains insufficient.
EFSA re-evaluation and group ADI: children may exceed safe intake
EFSA completed a re-evaluation of all phosphate food additives (E338 to E452) and set a group acceptable daily intake of 40mg per kilogram of body weight per day, expressed as phosphorus. Crucially, EFSA found that infants, toddlers, children, and adolescents who are high consumers of phosphate-containing foods may regularly exceed this group ADI. EFSA flagged this as a safety concern and called for more detailed exposure data. The ADI covers the combined phosphate additive intake, not any single additive in isolation.
EFSA set a group ADI of 40mg/kg body weight/day for phosphoric acid and phosphate salts (E338 to E452) and concluded that high-consuming infants, toddlers and children may exceed this ADI.
Where it stands with the regulators
Who should be careful
People with chronic kidney disease should avoid foods listing diphosphates, disodium diphosphate, tetrasodium diphosphate, or E450 on the label, and should seek dietary advice from their renal dietitian. People with hyperphosphataemia (raised blood phosphate levels) for any reason are similarly advised to limit additive phosphate. Parents of young children who eat a lot of processed meat, processed cheese, and packaged baked goods may wish to track how frequently these products appear in the diet.
The honest read
The genuine divide in the science is about who is harmed and how much. For people with healthy kidneys eating a mixed diet, the kidneys handle surplus phosphate and evidence of harm in the general population remains associative rather than causal. For people with reduced kidney function, the case for avoiding additive phosphate is well-established and clinically acted upon. The complicating factor for everyone is that food labels do not tell you how much phosphate an additive contributes to total intake, and current food composition databases often omit additive phosphate entirely. EFSA's finding that children may exceed the group ADI adds a real unanswered question that regulators have not yet resolved with concrete labelling rules. The science on the general-population cardiovascular angle is active, not settled.
Related additives
Common questions
Is E450 banned in the UK?
No. E450 diphosphates are approved for use in the UK under the assimilated EU Regulation 1333/2008 and the UK FSA's approved-additives list. The additive is authorised in England, Scotland and Wales.
Is E450 a concern for people with kidney disease?
Yes, and it is a well-established clinical concern, not just a precautionary one. Phosphate from food additives is absorbed at around 90 percent, far higher than phosphate from natural foods. For people with reduced kidney function, this additive phosphate load can elevate serum phosphate, which is associated with accelerated kidney decline and cardiovascular strain. Renal dietary guidelines specifically advise limiting foods that list E450 or diphosphates on the label.
What foods contain E450?
E450 appears most commonly in processed meats (ham, bacon, chicken nuggets, sausages), processed cheese slices and spreads, baking powder, self-raising flour, cake mixes, frozen potato products, and some instant noodle seasonings. Look for diphosphates, disodium diphosphate, tetrasodium pyrophosphate, sodium pyrophosphate, or E450 on the ingredient list.
Is E450 vegan?
The diphosphate salts themselves are mineral compounds, not derived from animals, so they are vegan. However, E450 is very commonly used in processed meat products, which are not vegan. Check the rest of the ingredient list for animal-derived ingredients.
Sources
- UK FSA: Approved additives and E numbers
- UK FSA Regulated Products: E450 Diphosphates
- EFSA ANS Panel re-evaluation of phosphoric acid and phosphates (E338 to E452), EFSA Journal 2019
- Calvo & Uribarri, Nutrition Reviews: Contributions to total phosphorus intake (2013)
- Ritz et al., Nephrology Dialysis Transplantation: Phosphate additives in food (2012)
- Springer, Nature Reviews Nephrology: Phosphate and CKD (2016)
- American Diabetes Association, Diabetes Spectrum: Phosphate additive avoidance in CKD (2017)
- Industrial use of phosphate food additives as a mechanism linking ultra-processed food to cardiorenal disease risk, Nutrients / PubMed (2023)
- European Journal of Clinical Nutrition: Food additives containing phosphorus in ultra-processed foods and chronic kidney disease (2025)
- Dietary phosphate exposure strategies to protect vulnerable population groups, PMC (2025)
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
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