E521 · Aluminum sodium sulfate
- WHO
- Safe
- FDA
- Safe
- EFSA
- Safe
- FSANZ
- Safe
- Japan
- Safe
- UK FSA
- Safe
- Health Canada
- Safe
What is E521?
Aluminum sodium sulfate (sodium alum) is a mineral salt occasionally used as an acidity regulator or firming agent, including in some baking powders. It contributes to the body's overall aluminum exposure, which EFSA has flagged as worth limiting because high cumulative intake from all dietary sources has been linked to potential neurological and reproductive effects in animal studies. It is now used less often than in the past as many manufacturers have shifted to aluminum-free alternatives.
Also appears on labels as: Aluminum sodium sulfate, Sodium aluminum sulfate, Alum sodium salt, E521, E 521, E-521, Food grade sodium aluminum sulfate, Aluminum sodium alum, Sodium aluminum additive, Alum additive, Sodium aluminum sulfate powder, Sodium alum.
What the evidence says
- Contributes to total dietary aluminum exposure; EFSA has set a tolerable weekly intake for aluminum compounds due to potential effects on the nervous system and fertility observed in animal studies.
- Not typically a concern from a single food item, but relevant for people trying to minimize overall aluminum intake.
Frequently asked questions
Is E521 safe?
Our overall verdict for E521 (Aluminum sodium sulfate) is “Safe”, based on the most cautious of the major regulators’ positions — FDA: safe; WHO: safe; EFSA: safe; FSANZ: safe; Japan: safe; UK FSA: safe; Health Canada: safe.
Is E521 vegan, halal or gluten-free?
According to our ingredient data for Aluminum sodium sulfate — vegan: yes, vegetarian: yes, halal: yes, kosher: yes, gluten-free: yes, dairy-free: yes. Manufacturing sources can vary between products; check the label if it matters to you.
What is E521 and why is it used?
Aluminum sodium sulfate (sodium alum) is a mineral salt occasionally used as an acidity regulator or firming agent, including in some baking powders. It contributes to the body's overall aluminum exposure, which EFSA has flagged as worth limiting because high cumulative intake from all dietary sources has been linked to potential neurological and reproductive effects in animal studies. It is now used less often than in the past as many manufacturers have shifted to aluminum-free alternatives.
Does E521 contain allergens?
No known allergens are recorded for Aluminum sodium sulfate.
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This page summarises publicly available regulatory assessments and research. It is general information, not medical advice. Sources: EFSA, FDA, WHO and the studies linked above.