# 4-hydroxybutanoic Acid Lactone

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**Safety rating:** UNKNOWN
**CAS number:** 96-48-0
**Category:** flavoring
**FDA GRAS:** no
**Adverse events (FDA AERS):** 0
**FDA recalls:** 0
**Last updated:** 2026-04-02

## Summary

4-hydroxybutanoic acid lactone, commonly known as gamma-butyrolactone (GBL), is a synthetic organic compound used as a flavoring agent in food products. It imparts a creamy, butter-like taste and is employed in small quantities to enhance the sensory profile of various food and beverage formulations.

## Regulatory status

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

## Detailed analysis

## What is 4-hydroxybutanoic Acid Lactone?

4-hydroxybutanoic acid lactone is a cyclic ester (lactone) with the chemical formula C₄H₆O₂ and CAS number 96-48-0. Also known as gamma-butyrolactone or GBL, this compound is a colorless to pale yellow liquid with a characteristic buttery aroma. It occurs naturally in small quantities in some foods but is typically synthesized for industrial applications. The compound is structurally distinct from gamma-hydroxybutyrate (GHB), though they share a similar chemical origin and naming convention.

## Common Uses

4-hydroxybutanoic acid lactone is utilized primarily as a flavoring agent and flavor adjuvant in the food industry. Its creamy, buttery sensory profile makes it valuable in dairy-based products, baked goods, confectionery, and savory foods. It is typically used in very small concentrations—often measured in parts per million—to achieve desired flavor enhancements without significantly altering the product's composition. The compound is also used in non-food applications including cosmetics and pharmaceutical formulations, though this content focuses on its food safety profile.

## Safety Assessment

The FDA has not granted 4-hydroxybutanoic acid lactone Generally Recognized As Safe (GRAS) status, which means it does not have blanket approval for use in food in the United States. However, the absence of GRAS status does not necessarily indicate safety concerns; rather, it reflects that the compound has not undergone the formal GRAS notification process or petitioning procedure with the FDA.

According to FDA records, there have been zero reported adverse events and zero recalls associated with this additive, suggesting that if it is currently in use, it has not generated safety concerns at consumption levels in food products. This absence of adverse event reports is significant when evaluating real-world safety data.

The European Food Safety Authority (EFSA) has established an acceptable daily intake (ADI) for gamma-butyrolactone, indicating that regulatory bodies in other jurisdictions have conducted toxicological assessments. Typical safety studies have examined acute and subchronic toxicity in animal models.

## Regulatory Status

In the United States, 4-hydroxybutanoic acid lactone may be used in food under FDA regulations governing direct food additives if it meets certain criteria or is marketed under specific regulatory pathways. Its regulatory status differs from approved food additives and from GRAS substances. Manufacturers using this ingredient in food products should verify current FDA regulations and ensure compliance with labeling requirements.

In the European Union, gamma-butyrolactone is listed as a flavoring substance and is subject to the regulations governing food flavorings. Its use is permitted within established parameters, reflecting a regulatory determination of safety when used as intended.

The compound's status varies internationally; some jurisdictions permit its use in food with specific limitations, while others may restrict or prohibit it. Food manufacturers must comply with regulations in their specific markets.

## Key Studies

Toxicological evaluations of 4-hydroxybutanoic acid lactone have been conducted to assess its safety profile. These studies typically evaluate acute toxicity through oral administration, as well as subchronic effects over extended exposure periods. Available data suggest the compound has low acute toxicity, with LD₅₀ values in animal studies indicating relatively high doses would be required to produce adverse effects.

Studies have examined metabolic pathways and potential conversion to other compounds. The compound appears to undergo hepatic metabolism and is eliminated relatively quickly, which supports its safety profile when used in minor food applications.

Regulatory acceptance in Europe and the establishment of an ADI reflects confidence in the scientific safety data available for this substance at anticipated consumption levels in food.

## 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. "4-hydroxybutanoic Acid Lactone — Safety, regulation, and evidence." https://additivefacts.com/additives/4-hydroxybutanoic-acid-lactone. Accessed 2026-05-19.