E524 / Acidity regulators & anti-caking agents
Sodium hydroxide
Safety in brief
Safe
Recorded EatMatrix rating, not a new clinical review. The amount, your sensitivities and country rules still matter.
- Watch for
- No allergen or sensitivity is recorded for this ingredient here. Check the whole product label; this is not an allergen-free guarantee.
- Our advice
- Read the whole food label and consider how often you eat the product. A name or E number does not tell you the amount, and an ingredient rating cannot assess the entire food.
What it is
Sodium hydroxide (E524), also known as caustic soda or lye, is used in small controlled amounts in food processing, for example to cure olives, treat pretzels and some baked goods (giving pretzels their characteristic crust), and adjust pH in cocoa processing. It reacts and is largely neutralized during processing, so residual levels in finished food are very low.
Also appears on labels as: Sodium hydroxide, NaOH, Caustic soda, Lye, Food grade sodium hydroxide, Sodium hydroxide solution, Sodium hydroxide pellets, Sodium hydrate, Sodium oxide hydroxide, Industrial grade sodium hydroxide, E524, E 524.
Dietary information
- Vegan
- Yes
- Halal
- Yes
- Gluten-free
- Yes
- Allergens
- None recorded
Recorded ingredient information. Check the product label or certification: sources, other ingredients and cross-contact can vary.
Research & body effects
Health notes from our ingredient record
- Considered safe at the trace residual levels present in finished food; concentrated sodium hydroxide is corrosive, but this is a manufacturing handling concern, not a risk to consumers eating the finished product.
Other references from our ingredient record
These links come from the original ingredient record. They are separate from the source reviews above and have not all been checked for the exact ingredient, amount consumed or claim. Dates are shown newest first.
- Safety Assessment of Common Food Additives: Sodium Hydroxide Analysis — Food Safety and Toxicology Research Group, Food Additive Safety and Health Journal (2024). A comprehensive 2024 safety assessment examining sodium hydroxide (E524) among other common food additives, focusing on reproductive, oxidative, and enzymatic perspectives. The study confirmed that sodium hydroxide is safe when used as a pH regulator and processing aid according to approved guidelines. The research noted its effectiveness in food processing applications while confirming adequate safety margins at authorized usage levels. The assessment supports continued use with proper handling and application procedures.[safe]
Country rules
Country checks for E524
Permission depends on the market, type of food, amount and conditions. A scientific opinion or an E-number alone does not establish a legal use. These checks are separate from the stored EatMatrix rating.
Compare all eight markets and their sources
| Market | What is checked |
|---|---|
| European Union | Regulation (EC) 1333/2008, Annex II Part B, version , contains the exact code E524: Sodium hydroxide. Listing alone does not allow every food use. Part E food categories, limits, specifications and applicable later acts still need a product-specific check. Source read: . |
| Great Britain | The FSA register record for E524 (Sodium hydroxide) lists “Authorised” in England, Scotland and Wales. Register updated: 01 April 2025; record checked: . Food-specific conditions and specifications still need a separate legal check. |
| United States | Selected US conditions for Sodium hydroxide Official federal text current through ; read . Food uses, limits and exceptionsNamed preparation and use conditions The specified food-grade sodium hydroxide is listed for pH control and processing under good manufacturing practice. This does not make industrial lye or direct consumption of concentrated alkali equivalent to a controlled food process. EatMatrix’s reading: a legal use condition answers where and how an ingredient may be used. It is not a test of your product, a personal safe intake or a claim that the ingredient benefits your body. Match the named substance, food and amount. Other federal provisions, food standards, state rules and later changes may also apply; this is a selected source review, not a complete product-compliance decision. |
| Northern Ireland | Review pending. Check the applicable EU rules and territory arrangements; the GB register alone does not establish this status. FSA guidance is a starting source, not a verified permission for this entry. |
| Canada | Named food-use records located. Health Canada lists the preparations below for specified foods and purposes. This is conditional permission for those uses, not approval of every product or a personal safety verdict. Only the named records and conditions below were located. Exact composition and specifications still need matching. Source tables captured . List publication dates are shown separately. Good Manufacturing Practice (GMP) is a condition of use, not an unlimited amount or a recommended intake. Food and Drug Regulations B.16.003 requires the listed source, purpose, amount and other conditions to match. The official consolidation read was current to 21 September 2026; product specifications and applicable later changes still need checking. Read 10 listed food-use conditionsSodium HydroxideHealth Canada: List of Permitted Food Additives with Other Purposes of Use. List published ; item S.14.
Sodium HydroxideHealth Canada: List of Permitted Acidity Regulators and Acid-Reacting Materials. List published ; item S.13.
Sodium HydroxideHealth Canada: List of Permitted Starch-Modifying Agents. List published ; item S.5.
EatMatrix reading: match the exact preparation and food first. A manufacturing limit is not an acceptable daily intake (ADI). A label without the amount cannot establish exposure, and an unlisted name here does not establish a ban. |
| Australia | Review pending. Food Standards Code permissions and conditions need an additive-specific check. FSANZ food-additive rules is a starting source, not a verified permission for this entry. |
| New Zealand | Review pending. Food Standards Code permissions and conditions need an additive-specific check. FSANZ food-additive rules is a starting source, not a verified permission for this entry. |
| Japan | Review pending. The relevant list, identity and use standards need an additive-specific check. CAA food-additive lists is a starting source, not a verified permission for this entry. |
Sources & review status
Check what each source covers: an authority’s conclusion, a research finding and a country’s legal permission answer different questions.
What this guide covers
- Original ingredient record
- 1 research link; newest recorded date: . Sources added separately to this guide are not included in this count.
This guide brings together our ingredient record and the dated sources shown here. Missing information describes a gap in this guide; it does not mean an ingredient is untested, safe or harmful. This is not a complete review of every study, preparation or current country rule. The amount in a product and how it is used still matter.
How to read the ratings, research and country checksAgency labels recorded by EatMatrix
These are imported database classifications, not verified current statements from each authority. Use the dated official sources below for their actual scope and conclusions.
| Authority | Database label |
|---|---|
| FDA | Safe |
| WHO | Safe |
| EFSA | Safe |
| FSANZ | Safe |
| Japan | Safe |
| UK FSA | Safe |
| Health Canada | Safe |
Database updated: . What does an E number mean on a food label?
Common questions
Frequently asked questions
What is EatMatrix's recorded rating for E524?
The recorded EatMatrix rating for E524 (Sodium hydroxide) is “Safe”. It is calculated from labels stored in our ingredient database. These labels are not verified current regulator decisions or country permissions. A database update date is not a scientific review date.
Is E524 vegan, halal or gluten-free?
According to our ingredient data for Sodium hydroxide — 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 E524 and why is it used?
Sodium hydroxide (E524), also known as caustic soda or lye, is used in small controlled amounts in food processing, for example to cure olives, treat pretzels and some baked goods (giving pretzels their characteristic crust), and adjust pH in cocoa processing. It reacts and is largely neutralized during processing, so residual levels in finished food are very low.
Does E524 contain allergens?
No known allergens are recorded for Sodium hydroxide.
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This page shows information and classifications recorded in our ingredient database. Current scientific and market-specific verification remains pending as described above. It is general information, not medical advice.