Potassium phosphates
Potassium salts of phosphoric acid, used to preserve, emulsify, and control acidity in processed foods.
Phosphates added to processed food contribute to total dietary phosphorus load. High phosphorus intake is linked to impaired kidney function over time, and people with existing kidney disease cannot clear it efficiently. Regular high intake may also disrupt calcium and bone balance.
What is it?
Potassium phosphates are the potassium salts of phosphoric acid. The group covers three forms: monopotassium phosphate (E340a), dipotassium phosphate (E340b), and tripotassium phosphate (E340c). They are water-soluble white powders or granules derived from phosphoric acid and potassium carbonate or potassium hydroxide.
What does it do?
Acts as an acidity regulator, keeping pH stable in processed foods. Also functions as an emulsifier (helping fat and water mix in processed cheese and coffee creamers), a sequestrant (binding metal ions that would otherwise cause rancidity), a moisture-retention agent in meat products, and a leavening agent in baked goods. In beverages it buffers acidity and improves texture.
Where you will see it
Found in processed cheese and cheese slices, UHT cream, flavoured milk drinks, instant coffee, powdered creamers, cured and reformed meat products, surimi (fish sticks), bread and cake mixes, and sports or protein drinks. On UK labels it appears as 'potassium phosphates', 'dipotassium phosphate', or 'E340'.
What the science says
Kidney function and phosphate load
Phosphates added to processed food are absorbed more readily than naturally occurring phosphorus in whole foods. The kidneys must filter and excrete the extra load. In people with chronic kidney disease (CKD) this capacity is reduced, leading to elevated blood phosphate, which is associated with cardiovascular complications and faster disease progression. Even in healthy adults, consistently high phosphorus intake strains kidney filtration capacity over time.
EFSA's 2019 re-evaluation set a group ADI of 40 mg phosphorus per kg bodyweight per day for all phosphate food additives (E338-341, E343, E450-452), noting the ADI is not protective for people with moderate to severe kidney impairment.
Inorganic phosphate from food additives is absorbed at approximately 80-100% efficiency, compared with around 40-60% for organic phosphorus in whole foods, meaning additive phosphate raises blood phosphate more per milligram consumed.
High serum phosphate, driven partly by additive intake, is independently associated with increased cardiovascular mortality in CKD patients and in the general population in some prospective cohort studies.
Bone and calcium balance
Phosphorus and calcium are tightly coupled in the body. Chronically high phosphorus intake relative to calcium can suppress parathyroid hormone regulation and reduce calcium absorption, potentially affecting bone density over a long time horizon. The effect in healthy adults eating a varied diet is considered small, but the signal is present in epidemiological data.
EFSA noted that the calcium-to-phosphorus ratio matters for bone health and that dietary phosphate excess relative to calcium can negatively affect bone mineral density.
An intervention study found that increasing phosphorus intake while keeping calcium constant raised PTH levels and reduced markers of bone formation, suggesting a negative effect on bone turnover.
Total dietary phosphorus and processed-food patterns
Added phosphates are concentrated in ultra-processed foods. People who eat a lot of processed meat, instant products, and processed cheese can consume several times the background phosphorus from whole foods. Because labels do not show phosphorus content in the UK or EU, it is difficult for consumers to track their total additive-phosphate intake.
Studies of Western dietary patterns estimate that food additives may contribute 10-50% of total daily phosphorus intake in heavy processed-food consumers, substantially increasing the total load above whole-food diets.
Where it stands with the regulators
Who should be careful
People with chronic kidney disease or reduced kidney function should minimise intake of foods containing added phosphates, as their kidneys cannot clear the extra phosphorus efficiently. Look for 'potassium phosphate', 'dipotassium phosphate', 'tripotassium phosphate', or 'E340' on the ingredient list. People managing bone density or calcium absorption should also be aware of regularly high phosphate intake relative to calcium.
The honest read
Most of the concern about E340 and other phosphate additives is not about individual doses but about cumulative intake across a processed-food diet. If someone eats processed cheese, cured meats, flavoured drinks, and instant products daily, total additive phosphorus adds up. The 2019 EFSA review found the group ADI could be exceeded by high-end consumers. The risk is real and documented for people with kidney disease; the signal in the general population is present in cohort studies but harder to isolate from other features of a processed-food diet. The science is not settled on exactly where the threshold of harm lies for healthy adults, but the mechanism is well understood.
Related additives
Common questions
Is E340 banned in the UK?
No. Potassium phosphates (E340) are permitted food additives in the UK and EU under assimilated EU Regulation 1333/2008 and the UK FSA approved-additives list.
Should people with kidney disease avoid E340?
Yes. EFSA's 2019 safety review explicitly stated that the group ADI for phosphate additives does not protect people with moderate to severe kidney impairment. People with CKD are commonly advised by nephrologists to limit processed-food phosphate. Look for 'E340', 'potassium phosphate', or 'dipotassium phosphate' on labels.
What foods contain E340?
Processed cheese slices, powdered creamers, UHT cream, instant coffee, protein and sports drinks, cured and reformed meats, flavoured milk drinks, and some bread and cake mixes are common sources.
Is E340 vegan?
Yes. Potassium phosphates are synthesised from mineral sources and contain no animal-derived ingredients. They are suitable for vegans and vegetarians.
Sources
- EFSA re-evaluation of phosphoric acid-phosphates (E338-341, E343, E450-452) as food additives, EFSA Journal 2019
- EFSA press release: EFSA issues new advice on phosphates, June 2019
- UK FSA Approved additives and E numbers
- Calvo MS & Uribarri J, Contributions to total phosphorus intake: all sources considered, Seminars in Dialysis
- Dhingra R et al., Relations of serum phosphorus and calcium levels to the incidence of cardiovascular disease in the community, Archives of Internal Medicine
- Kemi VE et al., Increased calcium intake does not completely counteract the effects of increased phosphorus intake on bone, Nutrition Journal
- Leon JB et al., The prevalence of phosphorus-containing food additives in top-selling foods in grocery stores, Journal of Renal Nutrition
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