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Hydrolyzed Vegetable and Soy Protein

Last reviewed October 19, 2026

In plain words: Hydrolyzed vegetable protein is a savory flavoring made by breaking down plant proteins; when it is made with acid, it can contain a contaminant called 3-monochloropropane-1,2-diol (3-MCPD). Hydrolyzed soy protein is a flavoring or protein ingredient made from soy. Soy is a major food allergen and must still be named on labels, and foods containing hydrolyzed soy protein cannot claim "No MSG."

What the evidence review says

Hydrolyzed vegetable protein (including 3-MCPD)

Hydrolyzed vegetable protein is a savory flavoring made by breaking down plant proteins. When it is made with acid, it can contain a contaminant called 3-MCPD. In rats, 3-MCPD was linked with kidney and testicular tumors, and IARC classifies it as possibly carcinogenic to humans; regulators set limits for it in foods.

The protein hydrolysate itself is a mixture of amino acids and peptides, including free glutamate. The distinct concern is 3-MCPD from acid hydrolysis. In rats, 3-MCPD caused kidney tubule tumors and Leydig-cell tumors and, at higher doses, reduced sperm motility and testicular changes. IARC found sufficient evidence in animals and no human cancer studies, and classed it Group 2B. EFSA's group tolerable daily intake is 2 μg/kg body weight per day for 3-MCPD and its fatty-acid esters. Adult exposure was judged not to exceed that TDI; younger high consumers are the group EFSA highlighted. Compliant modern acid-HVP is controlled to low 3-MCPD, which is a different situation from uncontrolled acid hydrolysis.

Hydrolyzed soy protein

Hydrolyzed soy protein is a flavoring or protein ingredient made from soy. Soy is a major food allergen and must still be named on labels. Like other acid-hydrolyzed proteins, it can contain the contaminant 3-MCPD, which regulators limit. Foods containing it cannot claim 'No MSG.'

Two separate issues. Soy is a major food allergen, and hydrolysis does not by itself remove the duty to name soy. Acid hydrolysis can leave 3-MCPD; that contaminant has strong animal evidence and regulatory limits, described under hydrolyzed vegetable protein. Enzyme hydrolysis avoids the hydrochloric-acid route to 3-MCPD. Free glutamate in the hydrolysate is why foods containing it cannot claim 'No MSG.'

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This page is for general education. It is not medical advice and does not replace advice from your doctor, pediatrician, allergist or registered dietitian. Research changes; we review these pages when new evidence or rules come out. Last reviewed October 19, 2026.