Purified glycomacropeptide (GMP) has been used in dietary supplements and in functional foods and beverages, which are products that claim to provide some health benefit beyond basic nutrition. GMP is produced in cheese making when an enzyme called chymosin (also known as rennin) is added to milk. Chymosin breaks down the milk protein kappa-casein into para-kappa-casein and glycomacropeptide (GMP). Para-kappa-casein is a component of the cheese curd, while the GMP peptide is part of the whey. GMP is also formed in the stomach as a product of digestion by the enzyme pepsin.
GMP differs from other whey proteins, because it contains low levels of certain amino acids, namely phenylalanine, tryptophan, and tyrosine. Because GMP is the only known naturally occurring protein that does not contain phenylalanine, it may be beneficial to incorporate it into the diet of phenylketonuria (PKU) patients, who cannot metabolize phenylalanine. Research is ongoing in this area.
GMP also has relatively high amounts of branched-chain amino acids (BCAAs). BCAAs are believed to stimulate the production of cholecystokinin (CCK), a peptide released after eating that may act as a satiety-providing appetite suppressant. The effects of GMP supplementation on satiety have not been consistent in clinical trials. Other clinical studies have tested the effects of GMP in infant formulas and weight loss.
Well-designed clinical trials are needed before firm conclusions can be made regarding the use of GMP for any health condition.

Related Terms

Acetyl galactosamine, branched-chain amino acids (BCAAs), carbohydrate, casein glycomacropeptide (cGMP), casein glycopeptide (CGP), casein macropeptide (CMP), casein-derived peptide (CDP), caseinglycopeptide, caseinmacropeptide, caseinoglycomacropeptide, cheese, cholecystokinin (CCK), galactosamine, galactose, glucosamine, isoleucine, kappa-casein, milk, phosphorus, sialic acid (N-acetylneuraminic acid), sweet whey, valine, whey.

evidence table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Nutrition (Grade: C)
GMP is present in infant formulas that contain whey. Results from clinical trials testing the benefits of supplementing infant formula with GMP are conflicting. Additional research is needed before firm conclusions can be made.
Obesity/weight loss (Grade: C)
Whey protein, which contains GMP, has been found to be more filling than other types of protein. The effects of supplementary GMP on weight loss have been inconsistent in clinical trials. Additional research is needed.
Phenylketonuria (PKU) (Grade: C)
Individuals with PKU cannot metabolize the amino acid phenylalanine and must strictly follow a diet in which most dietary protein is provided by a phenylalanine-free amino acid (AA) formula. In clinical trials, purified GMP was found to be a safe and acceptable alternative to synthetic amino acids as the primary protein source in the nutritional management of PKU. Additional research is needed to confirm these results.
Supplementation in preterm and very low birthweight infants (Grade: D)
Hyperthreoninemia (high threonine levels) has been documented in infants fed a whey protein-predominant formula. This condition is associated with a risk of neurotoxicity during early development. Research has shown that an experimental formula based on acid whey without GMP lacked these toxic effects.