Background

• 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.

References

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