Casein Glycomacropeptide

ProteinCasein peptides

What is it

Casein glycomacropeptide (CGMP, or simply GMP) is a 64-amino-acid peptide released from kappa-casein by chymosin during cheese manufacturing. It is naturally found in whey from cheese production and is notable for being free of phenylalanine.

Evidence for 3 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Phenylketonuria (PKU) protein source

Strong Evidence

Multiple clinical trials support CGMP-based medical foods as a more palatable and physiologically beneficial alternative to amino acid-based formulas for PKU management.

Satiety and appetite control

Limited Evidence

Small trials suggest CGMP may stimulate CCK release and reduce food intake, but evidence for clinically meaningful weight effects is limited.

Gut health / pathogen binding

Limited Evidence

In vitro and animal studies show CGMP binds bacterial toxins. Human trials for diarrhea prevention have shown mixed results.

How it works

CGMP is resistant to digestion in the upper GI tract and reaches the colon largely intact, where it can be partially fermented. Its biological activities include modulating gut microbiota, binding bacterial toxins (notably cholera toxin and E. coli toxins), supporting immune function, and stimulating cholecystokinin release which may contribute to satiety. Because it contains no phenylalanine in its native form (though commercial preparations may contain trace amounts from contamination), CGMP is used as a protein source in medical foods for phenylketonuria (PKU) management. It is enriched with the amino acids it naturally lacks (tyrosine, tryptophan, histidine, methionine, leucine) to provide complete nutrition.

Dosage

For PKU medical food use, dosing is individualized based on patient needs and prescribed by metabolic specialists. As a general supplement, doses of 5-20 g/day have been studied for satiety and gut health.

When and how to take it

WHEN: Can be taken throughout the day. For satiety effects, consume 15-30 minutes before meals. HOW: Mix into shakes, foods, or take with water as directed.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

CGMP isolate (medical food)

Used in PKU formulas, typically combined with supplemental amino acids.

Highly purified, low phenylalanine

Whey-derived CGMP

General supplement-grade product.

May contain trace phenylalanine

Safety

Generally well tolerated. As a milk-derived protein, it should be avoided by people with milk allergy. Lactose-intolerant individuals usually tolerate it well as it contains minimal lactose. PKU patients require carefully manufactured preparations with verified low phenylalanine content.

Who should be cautious

Avoid in milk allergy. PKU patients should only use products specifically verified as low in phenylalanine and under metabolic dietitian supervision.

Interactions

No significant pharmacological interactions reported. May modestly affect absorption of medications taken with high-protein meals.

Food sources

Sweet whey (cheese byproduct)

Amount
Variable
%DV
—

Frequently asked questions

Is CGMP safe for people with PKU?⌄

Only PKU-formulated CGMP products with verified low phenylalanine content should be used by PKU patients, under metabolic dietitian supervision.

Does CGMP contain lactose?⌄

Most commercial CGMP preparations contain minimal to no lactose and are usually tolerated by lactose-intolerant individuals.

References

Casein Glycomacropeptide on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Casein Glycomacropeptide (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.