# Aluminum Hydroxide

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**Safety rating:** CAUTION
**CAS number:** 21645-51-2
**Category:** colorant
**FDA GRAS:** no
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-04

## Summary

Aluminum hydroxide (CAS 21645-51-2) is an inorganic compound used in food as a colorant and processing aid. It functions as a color adjunct to stabilize or modify the appearance of food products in specific regulated applications.

## Regulatory status

| Country | Status |
| --- | --- |
| United States | approved |
| European Union | not_evaluated |
| United Kingdom | approved |
| Canada | approved |
| Australia | approved |
| Japan | approved |
| South Korea | approved |
| Brazil | approved |
| China | approved |
| India | approved |

## Detailed analysis

## What is Aluminum Hydroxide?

Aluminum hydroxide is an inorganic chemical compound with the molecular formula Al(OH)₃. It appears as a white, gelatinous precipitate or powder. In food applications, it serves dual roles as a colorant (specifically a color adjunct) and processing aid. The compound is chemically distinct from other aluminum-containing food additives and has specific regulated uses within food manufacturing.

## Common Uses

Aluminum hydroxide has limited applications in food products. Where permitted, it is typically used as a processing aid in the production of certain foods, helping to clarify or stabilize products during manufacturing. As a color adjunct, it may be used to enhance or modify the color characteristics of specific food formulations. The compound is not widely used in mainstream consumer food products in most developed markets, with regulatory approval restricted to specific applications and jurisdictions.

## Safety Assessment

The safety profile of aluminum hydroxide in food is based on limited exposure data, as its use in food is restricted. Aluminum as an element has been extensively studied in nutrition and toxicology research. The FDA has not designated aluminum hydroxide as Generally Recognized As Safe (GRAS) for food use, which reflects the limited evidence supporting its necessity in food applications rather than documented safety concerns.

According to FDA records, there have been zero reported adverse events associated with aluminum hydroxide as a food additive, and zero product recalls have been initiated due to its presence. This absence of reported incidents reflects both limited use and lack of documented safety issues in the food supply.

The World Health Organization (WHO) and various national regulatory bodies have established acceptable daily intake (ADI) values for aluminum from all dietary sources combined, recognizing that aluminum exposure comes primarily from natural food components, drinking water, and other sources beyond food additives. When present in food products, aluminum hydroxide contributes minimally to total dietary aluminum intake.

## Regulatory Status

Aluminum hydroxide is not approved as a food additive in the United States under FDA regulations. It does not appear on the FDA's list of approved color additives or processing aids for general food use. In the European Union, aluminum hydroxide (listed as E221-228 and E520-523 in different formulations and contexts) has restricted use with specific applications defined by EU Regulation 1333/2008.

The regulatory distinction between jurisdictions reflects different risk-benefit assessments and policy approaches regarding aluminum-containing additives in food. Some countries maintain more restrictive positions, while others may permit use in defined applications with specified maximum levels.

## Key Studies

Scientific literature on aluminum hydroxide specifically in food is limited, reflecting its restricted use. Most aluminum safety research focuses on aluminum from all sources (food, water, cookware) rather than specific compounds. Studies examining dietary aluminum exposure typically conclude that food additive sources represent a minor contribution to total intake in populations with normal kidney function.

Research on aluminum bioavailability indicates that the form and chemical state of aluminum affects absorption. Regulatory agencies have noted that aluminum compounds vary in their physiological effects, warranting individual assessment rather than broad categorization of all aluminum additives.

## Sources

- FDA Substances Added to Food (CFSAN)
- OpenFDA Adverse Event Reporting System (AERS)
- OpenFDA Food Recalls
- EFSA OpenFoodTox
- EU Food Additive Portal

## Citation

Additive Facts. "Aluminum Hydroxide — Safety, regulation, and evidence." https://additivefacts.com/additives/aluminum-hydroxide. Accessed 2026-05-20.