Sodium phosphates

What it is

Sodium phosphates (E339) are synthetic salts derived from phosphoric acid. They are highly functional additives used as buffers (to control acidity) and emulsifiers (to keep fats and water mixed).

How it is used in food

Multi-purpose moisture binding, melting, buffering.

• Processed cheese slices (melts smoothly without separating)
• Cured deli meats (retains water to increase weight)
• Instant puddings and sauces

Health and safety

Additive phosphate load can stack up to unsafe levels in high consumers.

E339 shares the same significant health warning as all phosphate additives (E338, E450, etc.). The phosphorus in these additives is completely unbound, meaning your body absorbs nearly 100% of it rapidly, unlike natural phosphorus bound in plant proteins.

EFSA’s 2019 review warned about cumulative phosphate load.

Regulatory status

Identification on labels

E-number

E339

Also printed asdisodium phosphate · sodium phosphate · trisodium phosphate

Alternatives to this additive

• E331: Sodium citrates — Performs the same buffering and melting job in processed cheese without adding to dietary phosphate load.

How it is made

Produced industrially by neutralizing phosphoric acid (E338) with sodium carbonate or sodium hydroxide.

1. Synthesis — Phosphoric acid is reacted with a sodium or potassium base.

Worth knowing

Very common in processed foods and meats.

Conclusion

Inorganic phosphate is absorbed almost completely, unlike the phosphorus bound in plant foods, and a sustained excess shifts the body's calcium-phosphorus balance — associated with vascular calcification and bone demineralisation. The evidence is clearest for people with reduced kidney function. EFSA's 2019 re-evaluation found the group ADI is exceeded by children and by high consumers across the EU, which is the practical reason to keep total phosphate additive intake down.

References

• EFSA re-evaluation of phosphates — EFSA