The U.S. Food and Drug Administration has issued final guidance aimed at helping infant formula manufacturers and testing laboratories conduct Protein Efficiency Ratio (PER) studies to evaluate protein quality in infant formula products.
Announced on May 21, 2026, the guidance outlines FDA’s expectations for the design, conduct, evaluation, and reporting of PER studies, which play a critical role in ensuring infant formulas provide sufficient biological protein quality to support infant growth and development.
Protein is considered one of the most essential nutrients in infant nutrition, particularly because infant formula may serve as the sole source of nourishment for many babies during early life. FDA stated that PER studies are necessary to verify that proteins used in formula products meet nutritional quality standards required under U.S. regulations.
The finalized guidance is especially important for companies planning to introduce new infant formula products into the U.S. market. According to FDA, the document provides industry with clearer scientific and regulatory expectations on how PER studies should be conducted to satisfy federal quality factor requirements.
The agency noted that the guidance finalizes the approach first introduced in a draft version released in 2023. By converting the draft into final guidance, FDA aims to provide greater regulatory clarity and consistency for manufacturers and laboratories involved in infant formula development and testing.
FDA also emphasized that the guidance is part of broader efforts to strengthen and stabilize the infant formula supply chain in the United States. The agency has been working to support formula availability and encourage manufacturers to expand product development while maintaining strict nutritional and safety standards.
Key focus areas of the final guidance include:
Manufacturers and laboratories are encouraged to review the final guidance carefully before initiating PER studies. FDA also stated that companies may contact the Infant Formula Premarket Review Staff for protocol review, technical feedback, or regulatory questions related to study development.
The guidance represents another step in FDA’s ongoing strategy to improve transparency, scientific consistency, and regulatory preparedness within the infant formula industry while ensuring products meet nutritional requirements essential for infant health.