FDA Publishes Final Guidance on Protein Quality Studies for Infant Formula
Constituent Update
May 21, 2026
The U.S. Food and Drug Administration (FDA) has issued final guidance for manufacturers of infant formula and laboratories conducting testing on infant formula. The guidance was developed to help manufacturers and laboratories in the design, conduct, evaluation, and reporting of Protein Efficiency Ratio (PER) studies. Protein is an essential nutrient to support growth and development in infants. PER studies are used to assure the quality of the protein in the infant formula, which is often a sole source of nutrition for infants. The guidance is intended to help industry, particularly those looking to introduce new infant formula to the U.S. market, by outlining how the PER study can be conducted to meet FDA’s requirement that a new infant formula meets the quality factor of sufficient biological quality of protein.
This document finalizes the approach presented in the draft guidance issued in 2023.
This guidance is one of many steps FDA is taking to support a more resilient infant formula supply by providing manufacturers with information to help with their new infant formula submissions to FDA. Manufacturers and laboratories are encouraged to review the guidance and may contact the Infant Formula Premarket Review Staff (if_manufacturer_questions@fda.hhs.gov) with questions or to request protocol review and feedback before initiating PER studies.
For Additional Information
- Guidance for Industry: Protein Efficiency Ratio (PER) Rat Bioassay Studies to Demonstrate that a New Infant Formula Supports the Quality Factor of Sufficient Biological Quality of Protein
- Federal Register Notice
- Final Rule: Current Good Manufacturing Practices, Quality Control Procedures, Quality Factors, Notification Requirements, and Records and Reports, for Infant Formula
- Infant Formula Guidance Documents & Regulatory Information