E339 – Sodium phosphates - Food additives database

Safety grading ORANGE – SOME CONCERNS

E339 refers to the group of sodium salts of phosphoric acid: monosodium phosphate, disodium phosphate and trisodium phosphate. Regulators generally consider these additives technologically useful and of low acute toxicity, but there are credible medium‑term concerns around total phosphorus exposure and specific risks in vulnerable groups. The European Food Safety Authority (EFSA) re‑evaluated phosphoric acid and phosphates used as food additives in 2019 and set a group Acceptable Daily Intake (ADI) of 40 mg phosphorus per kilogram body weight per day (40 mg P/kg bw/day). Exposure modelling in that opinion indicated that a proportion of toddlers and children with high processed‑food consumption could exceed this ADI, especially when multiple phosphate additives are present in the diet. This is relevant because inorganic phosphate salts from additives are highly bioavailable and can increase serum phosphate more efficiently than many natural phosphorus sources.

Independent clinical and mechanistic literature associates higher phosphorus intake with adverse outcomes in people with chronic kidney disease (CKD), including progression of CKD, vascular calcification and cardiovascular events. While these risks are clearest in CKD, emerging reviews also flag potential cardiometabolic effects of sustained high‑phosphate diets in the general population. The U.S. Food and Drug Administration lists sodium phosphate (mono‑, di‑, tribasic) as generally recognised as safe (GRAS) when used in accordance with good manufacturing practice, which reflects typical levels in foods rather than pharmacologic dosing. Balancing the regulator baseline with global evidence, the weight of data supports caution rather than alarm.

We therefore grade E339 as ORANGE. The grade reflects a net‑risk judgement in which legal approval and long historical use are weighed against consistent medical concerns about high phosphorus load and the high absorption of additive phosphates compared with naturally occurring phosphorus in foods. For healthy consumers with balanced diets and moderate processed‑food intake, risk at typical use levels is likely low. However, for heavy consumers of processed meats, processed cheese and cola‑type beverages, and for anyone with reduced kidney function, a “some concerns” stance is justified. As always, overall diet quality and total phosphorus intake matter more than the presence of any single additive.

Should You Avoid E339?

Most people do not need to completely avoid E339, but limiting highly processed foods that list phosphate salts near the top of the ingredients is sensible. Those with chronic kidney disease, a family history of kidney problems, or advice to follow a low‑phosphorus diet should be especially cautious because additive phosphates are readily absorbed and can raise serum phosphate more than natural food phosphorus. Parents may also wish to moderate frequent intake of processed cheese slices, processed meats and cola drinks in young children.

Common Uses

Acidity regulation and buffering in beverages and many processed foods.
Emulsifying salts in processed cheese to improve melt and texture.
Water binding and moisture retention in processed meats and seafood.
Sequestrant to control metal ions and protect flavour and colour.
Leavening agent in baking powders and prepared doughs.

Common names / Synonyms

Monosodium phosphate (E339(i)), sodium dihydrogen phosphate, MSP
Disodium phosphate (E339(ii)), sodium hydrogen phosphate, DSP
Trisodium phosphate (E339(iii)), TSP
Sodium orthophosphates, sodium phosphates

What is it?

E339 covers three sodium orthophosphate salts derived from phosphoric acid by neutralisation with sodium hydroxide or sodium carbonate. Monosodium phosphate (NaH₂PO₄) is acidic and commonly used where buffering in the lower pH range is needed. Disodium phosphate (Na₂HPO₄) is near neutral and serves as a general‑purpose buffer and sequestrant. Trisodium phosphate (Na₃PO₄) is alkaline and can raise pH or act as a processing aid. Commercial food‑grade material is produced via neutralisation and crystallisation, followed by drying to achieve the required hydrate state and particle size. Specifications limit contaminants and define assay and pH ranges appropriate for each salt.

Functionally, sodium phosphates stabilise pH and bind divalent metal ions such as calcium and magnesium. In processed cheese they act as emulsifying salts, converting casein into a meltable, homogeneous matrix. In meat and seafood processing they increase ionic strength and water‑holding capacity to improve juiciness and yield. In baked goods certain phosphate salts contribute to chemical leavening by reacting with sodium bicarbonate to release carbon dioxide at predictable temperatures. Compared with organic phosphorus naturally present in foods, these inorganic salts are rapidly absorbed, which underpins both their technological usefulness and the nutritional concern when intake is high.

Where it’s allowed (EU vs US)

European Union: E339 is authorised across defined food categories as acidity regulator, sequestrant, stabiliser and emulsifying salt, under the group ADI (Acceptable Daily Intake) for phosphates expressed as phosphorus. EFSA has advised that food additives can account for a noticeable fraction of total phosphorus intake and recommended exposure management where needed.

United States: Monobasic, dibasic and tribasic sodium phosphates are generally recognised as safe (GRAS) when used in accordance with good manufacturing practice and are listed in federal regulations. Medical guidance, however, suggests patients with chronic kidney disease should limit highly absorbable inorganic phosphate salts.

E339 – Sodium phosphates