E-numbers / Other additives / E343
also: Monomagnesium phosphate · Dimagnesium phosphate · Magnesium orthophosphate
Mineral salts from phosphoric acid and magnesium, used to control acidity, prevent caking, and act as a raising agent in processed foods.
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Low Fat Milk (97%), Milk Protein, Magnesium Phosphate, Stabiliser (Carrageenan), Flavouring, Sweetener (Sucralose), Vitamin D3, Zinc Sulphate
Magnesium phosphates are the magnesium salts of phosphoric acid.
18
of the 43,325 UK supermarket foods we checked declare E343 in their ingredients
That is under 0.1%, counted by its code or its name.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Magnesium phosphates are the magnesium salts of phosphoric acid. Three forms exist under E343: monomagnesium phosphate (E343i), dimagnesium phosphate (E343ii), and trimagnesium phosphate (E343iii), differing in the ratio of magnesium to phosphate. They occur naturally in foods such as beans, nuts, and grains, and are produced commercially by reacting magnesium oxide or magnesium hydroxide with phosphoric acid.
They act as acidity regulators, buffering the pH of food products to keep texture and flavour stable. As anticaking agents they absorb moisture and stop powders clumping. As sequestrants they bind trace metal ions that would otherwise catalyse rancidity. The dimagnesium and trimagnesium forms also serve as leavening agents in baking, releasing carbon dioxide when combined with an acidic ingredient.
Used in food supplements and nutritional powders, baking powder, table salt and salt substitutes, processed cheese, dried milk, cocoa products, and some cereal-based foods. On a UK label it appears as 'E343', 'magnesium phosphate', or in the form of 'acidity regulator (E343)', 'anticaking agent (E343)', or 'raising agent (E343)'.
All phosphate additives, including magnesium phosphates, contribute to total dietary phosphate intake. For people with chronic kidney disease (CKD), the kidneys cannot excrete excess phosphate efficiently, which can raise blood phosphate levels and contribute to bone and cardiovascular complications. Phosphate from food additives is absorbed more readily than from natural food sources. Clinical guidance for CKD patients routinely includes limiting phosphate additive intake.
Inorganic phosphate from food additives is absorbed at approximately 80-100% efficiency, compared with roughly 40-60% from naturally occurring organic phosphate in meat and grains, making additive sources a disproportionate contributor to phosphate load in people with impaired kidney function.
Elevated serum phosphate is independently associated with increased cardiovascular mortality in patients with chronic kidney disease.
Magnesium phosphates also deliver magnesium, an essential mineral involved in nerve function, muscle contraction, and bone formation. The magnesium component is bioavailable and can contribute positively to dietary magnesium intake at the levels typically found in food. The UK SACN has set dietary reference values for magnesium but has not flagged food-additive sources as a concern at current exposure levels.
EFSA set an Adequate Intake for magnesium of 300mg per day for adult women and 350mg for adult men, with food-additive sources contributing only a small fraction of typical daily intake.
EFSA conducted a systematic re-evaluation of phosphate additives (E338-341, E343, E450-452) as part of its programme to reassess all food additives authorised before 2009. The panel noted that combined exposure to phosphate additives across the whole group should be considered, particularly given high background dietary phosphate intake in modern diets. EFSA did not set a numerical ADI for the phosphate group as a whole, but noted that the no-observed-adverse-effect level from animal studies gave a margin of exposure considered adequate for the general population at current permitted use levels.
EFSA's re-evaluation of phosphate food additives (E338-343, E450-452) found no safety concern at current authorised uses and levels for the general population, but flagged that people with kidney disease represent a vulnerable group who may benefit from limiting all phosphate additive intake.
People with chronic kidney disease or impaired kidney function are generally advised by their renal dietitian to limit all phosphate additive intake. Look for 'E343', 'magnesium phosphate', 'acidity regulator (E343)', or 'raising agent (E343)' on the ingredients list.
For most shoppers, magnesium phosphates are an unremarkable mineral salt doing a functional job: keeping powders flowing, stabilising acidity, or helping baked goods rise. The magnesium itself is a dietary essential. The live area of concern is not the additive in isolation but the cumulative contribution of all phosphate additives to total dietary phosphate, which in a heavily processed diet can be high. For anyone with kidney disease, that cumulative load is clinically relevant. For everyone else, the science at present does not point to a specific risk from this additive at the levels used in food.
No. E343 is an approved food additive in the UK, listed on the FSA approved-additives list and authorised under assimilated EU Regulation 1333/2008.
People with chronic kidney disease are typically advised by their renal team to limit all phosphate additive intake, including E343. Phosphate from food additives is absorbed more efficiently than from natural food sources, which can raise blood phosphate levels when the kidneys cannot clear the excess.
E343 is used in food supplements, baking powder, table salt and salt substitutes, processed cheese, dried milk powders, cocoa products, and some cereals. It appears on labels as 'E343', 'magnesium phosphate', or described by function such as 'anticaking agent (E343)' or 'raising agent (E343)'.
Yes. Magnesium phosphates are produced from mineral sources (magnesium oxide or hydroxide reacted with phosphoric acid) and contain no animal-derived ingredients.
Last reviewed: 20 June 2026
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